title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 1, january 2019 subject index 1. alkaline pretreatment 2. alpha glukosidase 3. antihyperlipidemia 4. antioxidant 5. ceramic membrane 6. cfd modeling 7. clean water production 8. dilute acid pretreatment 9. lignin 10. low density lipoprotein (ldl) 11. melia azedarach linn 12. metals reduction 13. parkia speciose 14. petai pod 15. rice husk 16. river water treatment 17. standardization 18. total cholesterol 19. total flavonoid 20. total phenolic content 1 microsoft word subject index for.docx science & technology indonesia subject index 1 subject index for volume 1 number 1 october 2016 v bentonite v biodiesel v calcium oxide v catalyst v insertion v intercalation v layered double hydroxide v organometallic v polyoxometalate v portunus palagicus linn v silica oxide microsoft word sti author index.dotx science & technology indonesia author index 1 author index for volume 1 number 1 october 2016 v donny marihot siburian v hasja paluta utami v maria danesti situngkir v minaria v muhammad said v neza rahayu palapa v risfidian mohadi v yuliza hanifa v yunita sari m a title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 author index 1. aldes lesbani 2. ario firana 3. budi untari 4. dina permata wijaya 5. ferra yanuar 6. hazmira yozza 7. herlina 8. indah solihah 9. khairunnisa 10. mardiyanto 11. najma annuria fithri 12. neza rahayu palapa 13. ratna vrima rescha 14. riana sari puspita rasyid 15. risfidian mohadi 16. sofia sandi 17. tarmizi taher 18. tri suciati 19. via angraeni 20. zahrul mawaddah 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 3, july 2020 author index 1. abdul rahim yacob 2. des alwine zayanti 3. ferra yanuar 4. firmansyah burlian 5. indah meiliana sari 6. indah solihah 7. irsyadi yani 8. mardiyanto 9. nayla desviona 10. nur fatin sulaiman 11. sarmada 12. siew ling lee 13. thio gunawan jaya 14. yulia resti 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 2, april 2020 author index 1. aldes lesbani 2. azmi khusnani 3. bela olivia mareta silaen 4. danurdara setiamukti 5. dodi devianto 6. elfita 7. evi yuliza 8. ferra yanuar 9. fitri maya puspita 10. indrawati 11. indrayani 12. moh. toifur 13. muhammad yerizam 14. nurlisa hidayati 15. oki dwipurwani 16. rahmawati ramadhan 17. renny citra ramadhani 18. risfidian mohadi 19. surya puspita sari 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 4, october 2019 author index 1. aldes lesbani 2. bakri rio rahayu 3. delianis pringgenies 4. evi yuliza 5. hamzarudin hikmatiar 6. ishafit 7. jeri rahmadan 8. mentari eka wahyuni 9. neza rahayu palapa 10. puspita, f.m 11. rini pramesti 12. risfidian mohadi 13. subagiyo 14. tarmizi taher 15. wilis ari setyati 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 3, july 2018 subject index 1. adsorption 2. accumulation 3. aquatic vegetation 4. bioindicator 5. bioinsecticides 6. community structure 7. diversity index 8. ecosystems 9. entomophagous and phytophagous insects 10. heavy metal 11. irigation canal 12. lichen 13. modi�ed alkyd resin 14. pesticides 15. transplantation 16. waste palm oil 17. water quality 18. zeolites 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 2, april 2019 subject index 1. assessment 2. bio briquette 3. co-precipitation 4. fibonacci numbers 5. flood control 6. gibonacci numbers 7. identities 8. layered double hydroxides 9. ldhs 10. lucas numbers 11. mes production 12. particle size 13. retention basin 14. rubber seed 15. rubber seed oil 16. sum of cubes 17. surfactants 18. temperature 19. zn/al ldhs 20. zn/cr ldhs 21. zn/fe ldhs 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 4, october 2020 subject index 1. biogenic amines 2. chromatography 3. classification system 4. conveyor belt speed 5. cutting stock problem 6. disconnected 7. diurnal rainfall 8. ecmwf-era5 9. electrochemical sensor 10. finite difference method 11. graph 12. histamine 13. hyperbolic schemes 14. labeled, loops 15. mathematical models 16. näıve bayestwo-dimensional waves 17. optical sensor 18. partial differential equations 19. pattern generation 20. peatland 21. sesame 22. set covering model 23. vertices 1 microsoft word subject index for.docx science & technology indonesia subject index 1 subject index for volume 2 number 1 january 2017 v adsorption v bentonite v boric oxide v congo red v layer double hydroxide v organometallic compound v polyoxometalate v procion red v silica oxide microsoft word author index for.docx science & technology indonesia author index 1 author index for volume 2 number 3 july 2017 v aldes lesbani v rriza sativa v intan permata sari v muhammad imron v muhammad said v nurlisa hidayati v risfidian mohadi v sabat okta ceria sitompul v triayu septiani microsoft word sti preface.dotx science & technology indonesia preface 1 preface volume 1 number 1 october 2016 science and technology is two major important disciplines to develop various aspects in the earth. to disseminate research results of science and technology then since october 2016 science and technology indonesia was founded. we are grateful for the first issue science and technology indonesia. science and technology indonesia is developed for all scientists to create scientific atmosphere not only in indonesia but also in the world. the first issue is special for various field of chemistry and we believe this journal can create good communication between all scientists and all academicians. we invite scientists to submit their article to science and technology indonesia. the submission process and guideline for preparing manuscript is available in the web. please do not hesitate to contact us for further information. science and technology indonesia will publish articles quarterly january, april, july, and october every year. editorial team article http://sciencetechindonesia.com article history received: 14 january 2017 received in revised form: 21 april 2017 accepted: 30 april 2017 doi: 10.26554/sti.2017.2.3.68-70 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 68-70 calcium oxide from pomacea canaliculata and babylonia spirata snails triayu septiani1*, nurlisa hidayati1, risfidian mohadi1 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university corresponding author email: triayuseptiani@gmail.com abstract the preparation of cao from golden snail (pomacea canaliculata) and lion snail (babylonia spirata) through decomposition at various temperature i.e 700o, 800o, 900o and 1000oc during 3 hours has been carried out. calcium oxide from decomposition were characterized using x-ray difractometer. furthermore, the characterization was continued using ft-ir spectrophotometer and determination of surface area using bet analysis. the results showed that the optimum temperature for preparation of cao from golden snail and lion snail at 900oc with 2θ values are: 32.2° , 37.4o , 54o , 64.2o , 67.3° and 32.4°, 37.5°, 67.5°, respectively. ft-ir spectra showed characteristic vibrations for the ca-o in the sample golden snail and lion snail combustion products at a temperature of 900oc. ca-o absorption of golden snail samples in the wavenumber around 362.62 cm-1 and lion snail seen in wavenumber around 384.76 cm-1 indicating the presence of ca-o vibration of the metal oxide of preparation. golden snail and the lion snail combustion at 900 oc temperature of each sample which has a surface area of 20.495 m2/g, while the lion snail 17.308 m2/g. pore diameter of golden snail 3.753 nm and 11.319 nm of lion snail. all cao can be categorized as mesoporous material. keywords: golden snail, lion snail, decomposition, cao introduction the development of acid base catalyst is still carried out until this decade due to application for industrial applications. research of development acid catalyst is sharply increased compared with basic catalyst due to easy synthetic way. the basic catalyst is important for preparation of biodiesel, which has renewable energy in the future. conventional basic catalyst such as sodium hydroxide, potassium hydroxide (group 1) or calcium oxide, barium oxide, and strontium oxide (group 2) is commercially available (elkins et.al, 2016). these catalysts are toxic and high price. thus the research to obtain economic and non-toxic basic catalyst is vital. calcium oxide is one of the basic catalyst commonly used for production of biodiesel from vegetable oils (wei et.al, 2009). calcium oxide is strong base and effective as catalyst for biodiesel production and conversion of natural sources to chemical bio-based products. commercial calcium oxide is produced from limestone by industrial process then the price is still expensive. in order to obtain calcium oxide with cheaper source, decomposition of calcium carbonate from natural sources is interesting. calcium carbonate can be obtained from various mollusk shells such as snails shell and decapoda shells such as crab shell. decomposition of calcium carbonate will produce calcium oxide as main product and calcium hydroxide as by-product. the successfully decomposition process is depending on temperature decomposition (chakraborty and banerjee, 2011). various sources of calcium carbonate from mollusk or decapoda have been used to produce calcium oxide such as mollusk (pila globosa) (agrawal et.al, 2012), several shells (viriya-empikul et.al, 2010), oyster shell (nakatani e.al, 2009), crab (scylla serrata) shell (boey et.al, 2009) and also fish bone (lesbani et.al, 2016). all calcium oxide from these preparation was successfully applied as catalyst for biodiesel production. in this research, golden snail (pomacea canaliculata) and lion snail (babylonia spirata) from local source in bengkulu, indonesia were decomposed at various temperatures to obtain calcium oxide. calcium oxide from decomposition process was characterized using xrd powder analysis, ftir spectroscopy analysis, and surface area analysis using nitrogen sorption desorption. experimental section chemicals and instrumentations methanol was supplied from merck and used directly after purchased. water was supplied from department of chemistry, sriwijaya university by pore ion exchange filtration method. golden snail and lion snail were obtained from “pantai panjang” in bengkulu area. ftir spectrum was recorded using shimadzu prestige-21 ftir spectrophotometer by kbr method. spectrum was scanned from wavenumber 300-4000 cm-1. xrd powder patterns were obtained from shimadzu labx-6000 diffractometer and sample was scanned at 1o min-1. surface area analysis was performed using autosorb iq automated gas sorption analyzer quantachrome. preparation of calcium oxide golden snail and lion snail was washed with water. shell of golden snail and lion snail was dried at 110 oc overnight. shell was crushed and sieve 100 mesh. material was washed with methanol for 24 hours following with drying at 100 oc overnight. sample was decomposed using furnace under oxygen atmospheric condition for 3 hours. temperature was adjusted at 700, 800, 900, and 1000 oc. sample was dried at 80 oc in oven and kept in desiccator under silica gel. material was then characterized using xrd powder, ftir, and surface area analyses. septiani et al. 2017/science & technology indonesia 2 (3) 2017:68-70 © 2017 published under the term of the cc by nc sa 4.0 license 69 results and discussion shell of golden snail and lion snail contains calcium carbonate. calcium carbonate is basic natural compound. decomposition was conducted in order to convert calcium carbonate to calcium oxide. on the other hand, decomposition is also to remove organic substances on shells. transformation of calcium carbonate to calcium oxide was occurred at 700-800 oc. thus this experiment using temperature range 700-1000 oc for decomposition of golden snail and lion snail. the results of decomposition of golden snail and lion snail showed that various weight of products were obtained. products were obtained in the range 22-45%(w/w) and did not depending on temperature. all products after decomposition were obtained in white bulky powder, thus analysis using xrd powder analysis was conducted for the first as shown in figure 1 for golden snail and figure 2 for lion snail. to know the optimum temperature decomposition of golden snail and lion snail shells, xrd powder patterns in figure 1 and 2 should be compared with xrd calcium oxide standard and also calcium carbonate and calcium hydroxide standard. all standard was obtained from joint committee on powder diffraction standard (jcpds). the jcpds data for calcium carbonate, calcium oxide, and calcium hydroxide is presented in table 1. figures 1 and 2 showed that temperature decomposition at 900 oc give diffraction similar calcium oxide standard from jcpds data. other decomposition temperatures did not give any significant with calcium oxide standard as shown in table 1. temperature decomposition at 1000 oc has diffraction of calcium hydroxide (lesbani et.al, 2013). this phenomenon is due to hot material calcium oxide at high temperature will absorb water from air. temperature below 900 oc is not enough to convert calcium carbonate to calcium oxide, then small diffraction of calcium carbonate was still remained. thus further characterization using ftir spectroscopy will measure material after decomposition at 900 oc for both golden snail and lion snail. ftir spectrum of calcium oxide from decomposition of golden snail and lion snail at 900 oc is shown in figure 3. the ir spectrum is compared with ir spectrum of calcium oxide standard. if the vibration of decomposed material is similar with standard, then decomposition of golden snail and lion snail shell is successfully conducted. ftir spectrum of golden snail and lion snail is almost similar. vibration of ca-o of lion snail was appeared at wavenumber 362.6 cm-1 while golden snail at 384.8 cm-1. stretching vibration of o-c-o from carbonate was also appeared in both golden snail and lion snail. that vibration was appeared at wavenumber 1419.6 cm-1. in the other sides, bending vibration of c-o was appeared at wavenumber 870 cm-1. vibration at around wavenumber 860 cm-1 is typical for calcium carbonate (tang et.al, 2013). although decomposed material has small peak vibration of calcium carbonate but according to xrd powder patterns in figure 1 and 2, we can conclude that decomposition of golden snail and lion snail shells is successfully conducted at 900 oc and physical properties of decomposed material similar with calcium oxide standard. further characterization of decomposed material was conducted using surface area analysis by nitrogen sorption desorption. the results of surface area analysis toward golden snail and lion snail decomposed at 900 oc are presented in table 2. data in table 2 showed that decomposed material from golden snail and lion snail shells was classified as mesoporous material. according to iupac, mesoporous materials are materials with pore diameter 2-50 nm. other classes are microporous and macroporous with pore diameter less than 2 nm and more than 50 nm, respectively. pore distribution for golden snail and lion snail shell decomposed at 900 oc is presented in figure 4 and 5, respectively. figure 1. xrd powder patterns of decomposition of golden snail shell at various temperatures. figure 2. xrd powder patterns of decomposition of lion snail shell at various temperatures. table 1. diffraction standard of cao, caco3, and ca(oh)2 from jcpds file data. compound diffraction 2θ (deg) calcium oxide calcium carbonate calcium hydroxide 32.2 37.3 53.8 64.1 67.3 29.4 39.4 43.2 47.4 48.5 28.6 34.1 47.1 50.8 lion snail golden snail septiani et al. 2017/science & technology indonesia 2 (3) 2017:68-70 © 2017 published under the term of the cc by nc sa 4.0 license 70 conclusion decomposition of golden snail and lion snail was achieved at 900 oc for 3 hours to obtain calcium oxide. calcium oxide from decomposition has diffraction similar with calcium oxide standard from jcpds data. ftir spectrum showed typical vibration of cao and surface area analysis showed that calcium oxide from decomposition was mesoporous material. references agrawal. s., singh. b., sharma. y.c. (2012). exoskeleton of mollusk (pila globosa) as a heterogeneous catalyst for synthesis of biodiesel using used frying oil. industrial & engineering chemistry research, 51, 11875-11880. boey. p-l., maniam. g.p., hamid. s.a. (2009). biodiesel production via transesterification of palm olein using waste mud crab (scylla serrata) shell as a heterogeneous catalyst. bioresource technology, 100, 6362-6368. chakraborty. r., banerjee. s.b.a. (2011). application of calcined waste fish (labeo rohita) scale as low-cost heterogeneous catalyst for biodiesel synthesis. bioresource technology, 102, 3610-3618. elkins. t.w., roberts. s.j., hagelin-weaver. h.e. (2016). effects of alkali and alkaline-earth metal dopants on magnesium oxide supported rare-earth oxide catalysts in the oxidative coupling of methane. applied catalysis a: general, 528, 175-190. lesbani. a., tamba. p., mohadi. r., riyanti.f. (2013). preparation of calcium oxide from achatina fulica as catalyst for production of biodiesel from waste cooking oil. indonesian journal of chemistry, 13, 176-180. lesbani. a., sitompul. s.o.c., mohadi. r., hidayati. n. (2016). characterization and utilization of calcium oxide (cao) thermally decomposed from fish bones as a catalyst in the production of biodiesel from waster cooking oil. makara journal of technology, 20, 121-126. nakatani. n., takamori. h., takeda. k., sukugawa. h. (2009). transesterification of soybean oil using combusted oyster shell waste as a catalyst. bioresource technology, 100, 15101513. tang. y., xu. j., zhang. j., lu. y. (2013). biodiesel production from vegetable oil by using modified cao as solid basic catalyst. journal of cleaner production, 42, 198-203. viriya-empikul. n., krasae. p., puttasawat. b., yoosuk. b., chollacoop. n., faungnawakij. k. (2010). waste shell of mollusk and egg as biodiesel production catalysts. bioresource technology, 101, 3765-3767. wei. z., xu. c., li. b. (2009). application of waste eggshell as low-cost solid catalyst for biodiesel production. bioresource technology, 100, 2883-2885. figure 3. ftir spectrum of calcium oxide standard (c) and decomposed from golden snail (b) and lion snail shells (a). table 2. surface area analysis of decomposed golden snail and lion snail shells at 900 oc. decomposed sample surface area pore volume pore diameter (m2/g) (cm3/g) (nm) golden snail shell lion snail shell 20.495 0.052 11.319 17.308 0.069 3.753 figure 4. distribution of pore diameter for golden snail after decomposition at 900 oc. figure 5. distribution of pore diameter for lion snail after decomposition at 900 oc. (a) (b) (c) _goback title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 3, july 2020 research paper simulation study of autocorrelated error using bayesian �antile regression nayla desviona1, ferra yanuar2* 1,2department of mathematics, andalas university, limau manis campus, padang 25163, indonesia *corresponding author: ferrayanuar@sci.unand.ac.id abstract the purpose of this study is to compare the ability of the classical �antile regression method and the bayesian �antile regression method in estimating models that contain autocorrelated error problems using simulation studies. in the quantile regression approach, the data response is divided into several pieces or quantiles condition on indicator variables. then, the parameter model is estimated for each selected quantiles. the parameters are estimated using conditional quantile functions obtained by minimizing absolute asymmetric errors. in the bayesian quantile regression method, the data error is assumed to be asymmetric laplace distribution. the bayesian approach for quantile regression uses the markov chain monte carlo method with the gibbs sample algorithm to produce a converging posterior mean. the best method for estimating of parameter is the method that produces the smallest absolute value of bias and the smallest confidence interval. this study resulted that the bayesian �antile method produces smaller absolute bias values and confidence interval than the quantile regression method. these results proved that the bayesian �antile regression method tends to produce be�er estimate values than the �antile regression method in the case of autocorrelation errors. keywords �antile regression method, bayesian �antile regression method, confidence interval, autocorrelation. received: 20 may 2020, accepted: 16 july 2020 https://doi.org/10.26554/sti.2020.5.3.70-74 1. introduction parameter estimation in linear regression analysis is performed using the ordinary least squares method. this method has several assumptions that must be approved in order to get the best linear unbias estimator (blue). in some empirical data, not all assumptions can be ful�lled, such as autocorrelation among errors. then, the quantile regression method appears to overcome weaknesses in the ordinary least square (ols) method. this method uses a parameter estimation approach by separating or dividing data into quantiles by assuming conditional quantile functions in data distribution and minimizing the absolute symmetric weighted errors. this quantile regression analysis is used to overcome assumptions that are not met, including the existence of autocorrelation, normality assumptions, no multicollinearity and homogeneity of variances (yanuar et al., 2019a) large data size is usually needed in the quantile regression method. a sampling of large data requires a lot of time and a lot of energy. therefore it is used the bayes method to evaluate parameters with quantile regression. bayesian related to variable selection in quantile regression has received great attention in the literature because the bayes method is able to get good models with small data (oh et al., 2016), (yanuar et al., 2013), (yanuar et al., 2019d). in bayes’s views, the unknown parameter is assumpted as a random variable and has distribution. distribution related to the parameter can be obtained from corresponding previous research or based on expert opinion, this distribution known as the prior distribution. then, the prior distribution is combined with information from data obtained from sampling (known as likelihood function). the combination of both distribution then results in a posterior distribution of parameters. averages and variations of this posterior distribution are made estimators for the regression parameters by the bayesian method (yanuar et al., 2019b). in case of di�culties to identify the distribution of posterior distribution or because of complex formulation, bayesian method uses the mcmc (markov chain monte carlo) algorithm to estimate the mean posterior and variance posterior of the parameter model. in previous studies (muharisa et al., 2018), the bayesian quantile regression method with abnormal error has been discussed in the case of low birth weight (bblr) in west sumatra in the data of 2016 to 2018. furthermore (delviyanti et al., 2018) has been examined the application of the quantile regression with the bootstrap method to the autocorrelated error in the case of the interest rate on indonesia’s in�ation rate. this article https://doi.org/10.26554/sti.2020.5.3.70-74 desviona et. al. science and technology indonesia, 5 (2020) 70-74 will compare the ability of the quantile regression method and the bayesian quantile regression method in overcoming the autocorrelated error problem using a simulation study. 2. experimental section 2.1 materials 2.1.1 quantile regression the quantile method is one of the methods of regression modeling by dividing data sets into several equal parts with data sorted from the smallest or largest. quantile regression, in theory, is able to overcome the existence of autocorrelation, normality assumptions, heteroskedasticity, multicollinearity problems and etc. quantile regression minimizes asymmetric weighted data and agrees with the data function on the data distribution, (muharisa et al., 2018). linear equations for quantile � can be written with the equation : y = x ′ i �(�) + " (1) the general estimation for it to � can be written as follows: argmin x ′ i ���r n ∑ i=1 � � (yi − q�(y |x)) (2) where : � : show as quantile index �(0,1 ) � � : is an asymmetric loss function q � (y |x) = x ′ i � the quantile function to � from y on x condition, (yanuar et al., 2019a). 2.1.2 bayesian methods bayes introduced a parameter estimation method where we need to know the form of the initial distribution (prior) of parameters to �nd the estimated � parameter of the population, known as the bayesian method. the bayesian method uses the prior f (�) distribution together with the likelihood function to determine the posterior f (�|x1,x2, ...,xn) distribution (yanuar et al., 2019c) given y = (y1,y2, . . .yn) where the prior distribution of � is � (�). the prior distribution taken in this research is prior informative which is originating from previous research. determination of prior distribution parameters are very subjective, depending on the researcher’s intuition. 2.1.3 bayesian quantile regression a random variable of y is said to follow asymmetric laplace distribution (ald)(�, �, �) with location � parameter, scale of �>0 parameter and skewness p parameter in (0,1), the density function of the probability of ald as follows, (alhamzawi and yu, 2012) ; (feng and he, 2015). f (y|�,�,�) = p(1 − p) � exp(−�p( y − � � )) (3) where �p is loss function that is de�ned as follows : �p(u) = u(p − 1u<0) (4) with i shows the indicator function. (benoit and van den poel, 2010) ; (yanuar et al. (2019). 2.2. methods the data used in this study was data generated using r software version 3.6.1 (r development core team, 2011). the data used in this study consisted of two variables x1 and x2 each generated from n (0.1). while the dependent y variable was set with the value yt = 0.5x1t + 2x2t + "t ."t = sin(seq(0.1�, 15.0�, 0.1�)) + zt with ∼ n(0, 0.1) to t = 1, 2, ..., 150. 3. results and discussion in this section, we will describe the results of parameter estimations and comparisons for the quantile regression and bayesian quantile regression methods. 3.1. durbin watson (dw) test on simulation data in this study, to see the existence of autocorrelation in error from simulation data used the dubin watson test. based on the results of durbin watson (dw) using r version 3.6.1 software (r development core team, 2011) the statistical dw value was 0.124904. to �nd out whether the error of the simulation data was free from autocorrelation, we have compared the statistical dw values with dw table values. with the number of independent k variables was 2 and the number of n observations was 150. then the values for d l =1.7062 and du=1.7602 were obtained from the dw table values. in other words, based on the durbin watson test, if the dw value lies between 0 and d l stated that 0<dw<d l or 0<0.124904<1.7062. then h0 is rejected, the error contains autocorrelation. thus, in this case, the simulation data contains autocorrelated errors. 3.2. parameter estimation by using the quantile regression and bayesian quantile regression model at this step estimation parameters for quantile regression and bayesian quantile regression will be performed. the data consists of two variables x1 and x2 each generated from n (0,1). while the dependent y variable was set with the value yt = 0.5x1t + 2x2t + "t the quantile regression method is done by dividing or splitting the data into groups that have di�erent estimations of the results in the quantiles. in the bayesian quantile regression method, the results of estimation are also seen in each quantiles. the bayesian method uses the mcmc to estimate its posterior distribution with the help of r version 3.6.1 software (r development core team, 2011). the results of parameter estimation by the quantile method and the bayesian quantile method are presented in table 1. © 2020 the authors. page 71 of 74 desviona et. al. science and technology indonesia, 5 (2020) 70-74 table 1. estimated parameters by both methods. quantile quantile reg bayesian quantile reg to � �1 �2 �1 �2 0.1 0.5230* 1.9899 0.4308* 1.9356* 0.25 0.4722* 1.9996* 0.4325* 1.9357* 0.5 0.3787* 1.9632 0.4340* 1.9391* 0.75 0.4282* 2.0619* 0.4329* 1.9296* 0.9 0.4779* 2.0418 0.4230* 1.9366* figure 1. trace plot �1 with quantile 0.25 in table 1, it can be seen that the parameter estimation for �1 in quantile regression has been signi�cant for all quantiles by selecting the real level � = 0.05. whereas �2 is only signi�cant at the quantiles 0.25 and 0.75. while the estimated parameters for bayesian quantile regression for �1 and �2 have been signi�cant for all each quantiles with a real level � = 0.05. the analysis continued with the durbin watson (dw) test, to estimate the two methods by looking at the dw values in each quantiles, this aimed to �nd out whether the model meets the best linear unbias estimator (blue) by seeing no more assumptions that are violated. for the quantile regression method in the simulation data, the dw value was 2.0829 and the bayesian quantile regression had dw value 2.1132 with a p-value <0.05 . in the dw table with n=150 and k = 2 and the values, d l = 1.7249 and d l = 1.7915. based on the durbin watson test, if the dw value is located at d u < 4-d l , then h0 is accepted. thus, the error does not contain autocorrelation for both methods. likewise for quantile 0.25, 0.5, 0.75, 0.9. 3.3 comparison between the quantile regression method and the bayesian quantile regression in this section, we compared the estimated results of the model parameters with the two methods by estimating the value of the absolute bias and the width of the bayes con�dence interval. figure 2. plot density �1 with quantile 0.25 estimated results for both criteria are presented in table 2. based on table 2, it is known that the absolute bias value for �1 results of bayesian quantile regression tends to produce a smaller value than the quantile regression results. smaller values are marked in bold. while the absolute bias value for �2 results of the quantile regression tends to produce a smaller value than the bayesian quantile regression results. this is acceptable because the bayes estimator is a biased estimator so that the results of estimated posterior mean may slightly deviate from the true values. then the analysis results from table 2, also show that the con�dence interval is 95% for �1 and �2 with the bayes approach tends to produce a smaller value than the classical quantile method. this result is acceptable because the bayes method tends to produce a smaller variance so that in the calculation of the con�dence interval will also produce a smaller value than the classical quantile method. thus, it could be concluded that the bayes estimator method tends to produce better guess values than the quantile method in autocorrelated error cases. furthermore, the convergence test would be conducted for the parameters of the model that has been obtained. the convergence test used was by choosing a trace plot, density plot and autocorelation plot of the selected parameters. figure 1 presents a trace plot of the �1 parameter at the quantile 0.25. this �gure shows that the estimated values of the parameter with the iteration process has spread around two © 2020 the authors. page 72 of 74 desviona et. al. science and technology indonesia, 5 (2020) 70-74 table 2. comparison of absolute bias & interval of con�dence method of quantile regression and bayesian quantile regression. quantile absolute bias bayes credible interval to � qr bqr qr bqr �1 �2 �1 �2 �1 �2 �1 �2 0.1 0.023 0.01 0.0692 0.0643 0.5578 0.4438 0.3005 0.2792 0.25 0.0578 0.046 0.0475 0.0643 0.4381 0.3744 0.3205 0.2921 0.5 0.1212 0.037 0.0666 0.0609 0.304 0.3246 0.3231 0.2746 0.75 0.0718 1.794 0.0711 0.0704 0.2996 0.2891 0.2354 0.2912 0.9 0.052 0.072 0.0772 0.0634 0.4443 0.2955 0.3111 0.2962 figure 3. acf plot �1 with quantile 0.25 linear horizontal lines so the parameter is said to be convergent. the density plot model parameters for quantile 0.25 with �1 can be seen in figure 2 and for the acf plot can be seen in figure 3. in figure 3, the acf plot shows stationary data on average. it can be seen that the acf plot on the lag line above does not cross the 1.0 acf line. in this case, it can be said that there is no error containing autocorrelation for the selected quartile, the quartile 0.25 with the parameter �1. 4. conclusions this study used a simulation study to apply the quantile regression and bayesian quantile regression methods for autocorrelated errors. by comparing the quantile values in each parameters, and looking at the absolute bias values and the smallest con�dence interval for each quantiles in the parameter. the quantile regression method is done by dividing or splitting the data into groups that have di�erent estimates of the results in the quantiles. in the bayesian quantile regression method the parameter estimation results are also seen in each quantiles. the bayesian method uses mcmc to estimate its posterior distribution. the obtained results proved that the best method for estimating model parameter is the bayesian quantile regression method. by looking at the quantile value of each parameter, the smallest quantile 0.25 was obtained based on the absolute bias value and the smallest con�dence interval 95%. references alhamzawi, r. and k. yu (2012). variable selection in quantile regression via gibbs sampling. journal of applied statistics, 39(4); 799–813 benoit, d. f. and d. van den poel (2010). binary quantile regression: a bayesian approach based on the asymmetric laplace density. journal of applied econometrics delviyanti, o. s., f. yanuar, and d. devianto (2018). simulation study the implementation of quantile bootstrap method on autocorrelated error. cauchy: jurnal matematika murni dan aplikasi, 5(3); 95–101 feng, y., yang ; chen and x. he (2015). bayesian quantile regression with approximate likelihood. bernoulli, 21(2); 832–850 muharisa, c., f. yanuar, and d. devianto (2018). simulation study the using of bayesian quantile regression in nonnormal error. cauchy: jurnal matematika murni dan aplikasi, 5(3); 121–126 oh, m., j. choi, and e. sug (2016). bayesian variable selection in quantile regression using the savage–dickey density ratio. journal of the korean statistical society, 45(3); 466–476 yanuar, f., k. ibrahim, and a. a. jemain (2013). bayesian structural equation modeling for the health index. journal of applied statistics, 40(6); 1254–1269 yanuar, f., h. yozza, f. firdawati, i. rahmi, and a. zetra (2019a). applying bootstrap quantile regression for the construction of a low birth weight model. makara journal of health research, 23(2); 5 yanuar, f., h. yozza, and r. v. rescha (2019b). comparison of two priors in bayesian estimation for parameter of weibull distribution. science and technology indonesia, 4(3); 82–87 yanuar, f., h. yozza, and a. zetra (2019c). bayesian quantile regression methods in handling non-normal and heteroge© 2020 the authors. page 73 of 74 desviona et. al. science and technology indonesia, 5 (2020) 70-74 neous error term. asian journal of scienti�c research, 12(3); 346–351 yanuar, f., a. zetra, c. muharisa, d. devianto, a. r. putri, and y. asdi (2019d). bayesian quantile regression method to construct the low birth weight model. in journal of physics: conference series, volume 1245. iop publishing, page 012044 © 2020 the authors. page 74 of 74 introduction experimental section results and discussion conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 4, october 2019 research paper branch and cut method for solving capacitated vehicle routing problem (cvrp) model of lpg gas distribution routes yuliza, e1*, puspita, f.m1 1mathematics department, faculty of mathematics and natural science, university of sriwijaya, indralaya, south sumatera, indonesia *corresponding author: evibc3@yahoo.com abstract capacitated vehicle routing problem (cvrp) is a problem that discusses how to choose several routes that must be passed by a number of transport vehicles in the process of distributing goods that combine customer demand with regard to transport capacity. cvrp designs an optimal delivery route where each vehicle only takes one route, each vehicle has the same characteristics, each customer has a request and there is only one depot. in this paper, two cvrp models were formulated. formulation of the first cvrp model without regard to vehicle loads and vehicles returned to the depot. the second cvrp model formulation takes into account the vehicle load and the vehicle does not return to the depot. determination of lpg gas distribution routes is completed using the branch and cut method. keywords capacitated vehicle routing problem, branch and cut received: 23 september 2019, accepted: 19 october 2019 https://doi.org/10.26554/sti.2019.4.4.105-108 1. introduction the vehicle routing problem (vrp) and its variants hae grown popular. the capacitated vehicle routing problem (cvrp) deals with the distribution of a single commodity from a centralized depot to a number of speci�ed customer locations with known demands (achuthan et al., 2003; baldacci et al., 2004; ralphs et al., 2003). vehicle routing problem (cvrp) is a vrp subcase, where vehicles have limited capacity (beresneva and avdoshin, 2018). optimal route search in daily life is needed to minimize the time and costs incurred, especially for large companies that distribute their products every day by using a vehicle. the problem of �nding the optimal vehicle route or the vehicle routing problem (vrp) is a problem that discusses how to choose several routes that must be passed by a number of transport vehicles in the process of distributing goods that combine customer demand with regard to transport capacity. vrp was introduced by dantzig and ramser in 1959 on the problem of modeling truck deliveries. the problem under investigation is, how a homogeneous �eet of trucks can serve oil demand from a number of gas stations from the depot and minimize mileage. the purpose of this optimization is to �nd a set of routes that include n customers with a minimum overall distance (jepsen, 2011). the problem under study is how to serve a set of customers scattered around a central depot, using a �eet of trucks with various capacities (braekers et al., 2016). vrp has experienced developments that are tailored to realworld problems. a company faces a vehicle route problem to determine the optimal route. classic vrp aims to �nd a set of vehicle routes that start and end at a depot for vehicles with the same capacity so that each customer is visited exactly once (ate� et al., 2018). classic vrp is also known as capacitated vehicle routing problem (cvrp). cvrp designs an optimal delivery route where each vehicle only takes one route, each vehicle has the same characteristics, each customer has a demand and there is only one central depot to meet customer demand with the number of vehicle loads that does not exceed capacity. there are various integer linear programming (ilp) models from cvrp, as already examined (borčinova, 2017; alipour, 2012). one of the main di�erences lies in eliminating sub-tours, namely cycles that do not go through depots. cacceta et al. investigated that reducing the clarke and wright algorithm with a hybrid approach to cvrp completion (caccetta et al., 2012). achuthan et al. (2003) has developed an exact branch and cut algorithm. letchford et al. (2007) presents the branch and cut algorithm for the open routing problem, the vehicles are not required to return to the depot after completing service. in this study, the ilp model formulated from cvrp was solved by the branch and cut method. distribution of lpg gas products to several customers in the city of palembang. basically, this method attempts to strengthen the lower bounds by the addition of constraints (cuts) at each node within a branch and bound procedure (yang et al., 2000). pt. lebong terang is expected to be https://doi.org/10.26554/sti.2019.4.4.105-108 yuliza et. al. science and technology indonesia, 4 (2019) 105-108 able to create reliable shipping performance in the distribution of gas products. the conversion of kerosene to gas makes lpg gas demand continues to increase. during this time the distribution process that has been good, but not yet maximum which resulted in the long enough shipping distance and resulting in greater distribution costs, for this reason the company is expected to have a plan in determining the distribution channel so that the product distribution process can run optimally at a low cost . this research will formulate a cvrp model to determine the lpg gas distribution route using the branch and cut method. 2. experimental section the research is a case study, lpg gas distribution routes at pt terang lebong in palembang. the data is the result of a survey of 3 lpg gas base data collected by the surveyor, in the form of a list of veri�ed gas bases. table 1. parameters parameter description d1 demand for gas station 1 d2 demand for gas station 2 d3 demand for gas station 3 d4 demand for gas station 4 d5 demand for gas station 5 d6 demand for gas station 6 d7 demand for gas station 7 d8 demand for gas station 8 d9 demand for gas station 9 d10 demand for gas station 10 d11 demand for gas station 11 d12 demand for gas station 12 d13 demand for gas station 13 d14 demand for gas station 14 d15 demand for gas station 15 d16 demand for gas station 16 d17 demand for gas station 17 d18 demand for gas station 18 d19 demand for gas station 19 d20 demand for gas station 20 d21 demand for gas station 21 d22 demand for gas station 22 d23 demand for gas station 23 d24 demand for gas station 24 q vehicle capacity 2.1 materials the data used in this study is the distribution of 3 kg lpg gas. the gas is distributed to 24 gas bases (yuliza et al., 2019). 2.2 methods following are the research steps: 1. lpg gas demand data and distance from the agent to each gas base. 2. determine the distance matrix. 3. formulate the cvrp model. 4. solve the cvrp model using the branch and cut method. the calculation process uses the help of lingo 13.0 software. 3. results and discussion 3.1 mixed linear programming formulation of cvrp given the de�nition of variables and parameters. for each (i, j) � v, i ≠ j and for each vehicle r de�ned variable : x ij = { 1; if tℎereisatripfromtℎegasbasetoitotℎegasbasetoj 0; otℎerwisw } from table 1 de�ned parametres. vrp problems in lpg gas distribution can be determined as a graph g=(v,e). the set v consists of a combined set of p gas bases and warehouses, v={0,1,2,3,. . . ,24}. the set p is in the �rst gas base, the second gas base, ..., the 24th gas base, p={1,2,3,. . . ,24}. the set of vehicles is a collection of vehicles that are homogeneous with capacity. every base i for every i � v has a demand in so that the length of the route is limited by the capacity of the vehicle (q). for all pairs i,j�v,i≠j, we calculate the savings s_ij for joining the cycles 0→i→0 and 0→j→0 using arc (i,j); s ij =c i0 +c 0j -c ij (borčinova, 2017). table 2. solution of cvrp model with branch and cut method the milp model distribution distance traveled route from cvrp (km) 0-5-11 0.4 0-3-13 7.9 0-17-15 5,5 0-2-20 0.7 0-8-10 2.4 0-14-18 2.85 0-19-21 2.29 0-22-23 0.75 0-4-16 10.8 0-7-9 -1.2 0-12-1 10 0-6-24 -1.5 total 40,8 in this research, we present mixed integer linear programming (milp) model of cvrp. the objective function of the ilp model of cvrp minimizes the distance of travel (yuliza et al., 2019). now, instead of minimizing the distance of travel, will be maximize the total saving of the distance of travel. the cvrp model for lpg gas distribution is can be stated as: max 0.4x511+0.4x011 subject to x05+x011=1 x05+x115=1 x011+x511=1 x511<=1 x115<=1 y5+1050x511+4000x511-y11<=4000 © 2019 the authors. page 106 of 108 yuliza et. al. science and technology indonesia, 4 (2019) 105-108 table 3. compared the ilp model from cvrp and the milp model from cvrp the ilp model distance traveled the milp model distribution distance traveled distribution route from cvrp (km) route from cvrp (km) 0-5-11-0 4.8 0-5-11 0.4 0-3-13-0 21.9 0-3-13 7.9 0-17-15-0 31.5 0-17-15 5,5 0-2-20-0 9.1 0-2-20 0.7 0-8-10-0 7.2 0-8-10 2.4 0-14-18-0 7.25 0-14-18 2.85 0-19-21-0 4.19 0-19-21 2.29 0-22-23-0 1.65 0-22-23 0.75 0-4-16-0 17,8 0-4-16 10.8 0-7-9-0 5.8 0-7-9 -1.2 0-12-1-0 23.2 0-12-1 10 0-24-0 6.6 0-6-24 -1.5 0-6-0 5 total distance 145.99 40.8 y11+1200x115+4000x115-y5<=4000 y5>=1200 y5<=4000 y11=1050 y11<=4000 the function value of the cvrp model is 0.4 and the value x115 = 0.792, x011 = 0.792, x511 = 0.207, x05 = 0.207, y11 = 1050 and y5 = 4000. the decision variables are non-integer values so branching is done. after branching, the cvrp model is obtained : max 0.4x511+0.4x115 subject to x05+x011=1 x05+x115=1 x011+x511=1 x511<=1 x511<=1 y5+1050x511+4000x511-y11<=4000 y11+1200x511+4000x115-y5<=4000 y5>=1200 y5<=4000 y11>=1050 y11<=4000 x511<=0 the function value of the cvrp model is 0.4 and the value x115 = x011 = 1, x511 = x05 = 0, y11 = 1050 dan y5 = 4000. path 0→11→5→0 represents the route 0→11→5 where gas base 11 has demand 1050 kg, gas base 5 has demand 1200 kg, the value of the vehicle load is 1050 kg the value of the vehicle load is 4000 kg. milp model solutions from cvrp with the branch and cut method are shown in the table 2. 3.2 computational results both of the models, the ilp model distribution route from cvrp and the milp model distribution route from cvrp, were solved using lingo 13.0. from table 3 compared the ilp model from cvrp and the milp model from cvrp to get the optimal solution. ilp model from cvrp and milp model from cvrp were solved by branch and cut method. from the table 3., the optimal route of the ilp model from cvrp is 0-5-11-0 with travel distance 4.8 km. the optimal route of the milp model from cvrp is 0-5-11 with travel distance 0.4 km. the feasible route, 0→5→11→0 is replaced by a path from node 0 to node 11, 0→5→11. ratio of this travel distace from the ilp model from the cvrp and the milp model from the cvrp is 12 km. 4. conclusions from the result and discussion, it can be concluded the optimal solution of the cvrp model using branch and cut method is the route with optimum distance obtained as follows: 0-5-11 with an optimal distance of 12 km, 0-3-13 with an optimal distance of 7.9 km, 0-7-15 with an optimal distance of 5.5 km, 0-2-20 with an optimal distance of 0.7 km, 0-8-10 with an optimal distance of 2.4 km, 0-14-18 with an optimal distance of 2.85 km, 0-19-21 with an optimal distance of 2.29 km, 0-22-23 with an optimal distance of 0.75 km, 0-4-16 with an optimal distance of 10.8 km, 0-7-9 with an optimal distance of -1.2 km, 0-12-1 with an optimal distance of 10 km and 0-6-24 with an optimal distance of -1.5 km. percentage comparison of �ow formulation from cvrp and modi�ed assignment formulation from cvrp is 3.578 or 357.8 %. 5. acknowledgement this research is supported by faculty of mathematics and natural sciences, university of sriwijaya through sains and technology (sateks) research grant scheme, year 2019 © 2019 the authors. page 107 of 108 yuliza et. al. science and technology indonesia, 4 (2019) 105-108 references achuthan, n., l. caccetta, and s. hill (2003). an improved branch-and-cut algorithm for the capacitated vehicle routing problem. transportation science, 37; 153–169 alipour, m. m. (2012). a learning automata based algorithm for solving capacitated vehicle routing problem. international journal of computer science issues (ijcsi), 9(2); 138 ate�, r., m. salari, l. c. coelho, and j. renaud (2018). the open vehicle routing problem with decoupling points. european journal of operational research, 265(1); 316–327 baldacci, r., e. hadjiconstantinou, and a. mingozzi (2004). an exact algorithm for the capacitated vehicle routing problem based on a two-commodity network flow formulation. operations research, 52(5); 723–738 beresneva, e. and s. avdoshin (2018). analysis of mathematical formulations of capacitated vehicle routing problem and methods for their solution. proceedings of the institute for system programming of the ras, 30; 233–250 borčinova, z. (2017). two models of the capacitated vehicle routing problem. croatian operational research review, 8; 463–469 braekers, k., k. ramaekers, and i. v. nieuwenhuyse (2016). the vehicle routing problem: state of the art classi�cation and review. computers & industrial engineering, 99; 300–313 caccetta, l., m. alameen, and m. abdul-niby (2012). an improved clarke and wright savings algorithm for the capacitated vehicle routing problem. scienceasia, 38; 307 jepsen, m. k. (2011). branch-and-cut and branch-and-cut-andprice algorithms for solving vehicle routing problems. kgs. lyngby. denmark: technical university of denmark letchford, a., j. lysgaard, and r. eglese (2007). a branch-andcut algorithm for the capacitated open vehicle routing problem. journal of the operational research society, 58; 1642–1651 ralphs, t., l. kopman, w. pulleyblank, and l. trotter (2003). on the capacitated vehicle routing problem. mathematical programming, 94(2-3); 343–359 yang, x., a. i. mees, m. fisher, and l. jennings, editors (2000). progress in optimization. springer us yuliza, e., f. puspita, s. yahdin, and r. emiliya (2019). solution of capacitated vehicle routing problem using branch and cut method and clarke and wright algorithm for determining lpg gas distribution routes. conference on semirata & the 2nd icst unib © 2019 the authors. page 108 of 108 introduction experimental section materials methods results and discussion mixed linear programming formulation of cvrp computational results conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 2, april 2019 subject index 1. adsorption 2. artemia salina l 3. bayesian inference 4. bslt 5. carica papaya l 6. chitosan-alginate 7. cytotoxic 8. interaction 9. ionic-gelation 10. kinetic 11. kleinhovia hospita linn 12. lactic acid isolates 13. layered double hydroxide 14. mean square error 15. non-informative prior 16. papaya leaf 17. prior conjugate 18. submicron-particles 19. synthetic dye 20. thermodynamic 21. weibull distribution 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 1, january 2019 research paper alpha glukosidase inhibitory test and total phenolic content of ethanol extract of parkia speciosa plant fitrya1*, annisa a1, nikita s1, ranna c1 1pharmacy department, sriwijaya university jl palembang-prabumulih km 32 indralaya, ogan ilir sumatera selatan *corresponding author: fitrya_apt@yahoo.com abstract parkia speciosa (fabaceae), much grow in south sumatera. the seed of p. speciosa used as traditional medicine for diabetes mellitus therapy. another parts of p speciosa is suspected to have the same chemical compounds and potency as the seed. based on phytochemical screening of leaf and rind of p speciosa have secondary metabolites as flavonoid, phenolic and terpenoid. this research aims to know effectiveness of alpha glucosidase inhibitory effect of ethanol extract of rind, leaf and seed of p. speciosa and its correlation to total phenolic content of the extracts. the inhibitory activity of the alpha glucosidase enzyme was measured at λ 405 nm. the result showed that there was correlation between effectiveness of inhibitory and total phenolic content of the extract, that is the higher of the total phenolic content will caused the greater of enzymatic inhibition of extract. the ic50 of alpha glucosidase inhibitory effect of ethanol extract of rind, leaf and seed of p speciosa are 4,596 ppm, 54,341 ppm, dan 67,425 ppm and the total phenolic content of the extract are 138,15 mggae/g, 59,25 mggae/g, dan 36,25 mggae/g respectively. keywords parkia speciosa, total phenolic content, alpha glukosidase received: 29 august 2018, accepted: 16 september 2018 https://doi.org/10.26554/sti.2019.4.1.1-4 1. introduction diabetes mellitus is a chronic metabolism disorder which characterized by high blood glucose level, caused impaired insulin secretion or insensitivity of cell (si et al., 2010) . according to (idf, 2017), diabetes mellitus is including in the 7 to causes of death in the world on 2030. the raising of dm prevalences, especially diabetes mellitus type 2 (t2d) is a seriously problem. postprandial hyperglycemia plays an important role in the development of t2d (telagari and hullatti, 2015). one of antidiabetic agent for overcome postprandial hyperglycemia is alpha glucosidase inhibitor (kim et al., 2005). alpha glucosidase inhibitor act as competitive inhibitors of alpha glucosidase enzyme needed to digest carbohydrate. inhibition of this enzyme systems helps to reduce the rate of digestion of carbohydrates (bhat et al., 2011). natural product of great structural diversity are a good source for searching for such inhibitors (qaisar et al., 2014). the petai plant (parkia speciosa) distributed over all on south sumatera. traditionally, the seed of the plant used as antidiabetic agent, kidney failure and headache (azliza et al., 2012). the petai plant (parkia speciosa) have potency as alpha glucosidase inhibitor caused this plant contain �avonoids which spread all over of the plant. the p. speciosa seed has a terpenoid compound is lupeol which have anticarcinogen and antiin�amation acivity (kamisah et al., 2013). thiazolidyn-4-carbocylic acid and thioprolyn from petai seed has anticarcinogen too (chen et al., 2008). methanol extract of petai seed have 2464,3 mggae/g total phenolic content with antioxidant activity 5936,9 µmol troxol/g on dpph test and 1898,0 µmol troxol/g on frap test (ali et al., 2011). the chemical content can be discovered on some place but can be distributed all over of the plant. the rind and leaf of p. speciosa suspected have the same chemical content and expected has the same potency as the seed. phytochemical screening showed that leaf and rind of p speciosa contains �avonoid, phenolic and terpenoid. this research aim to know e�ectiveness of ethanol extract the leaf, rind and seed of p speciosa from south sumatera as alpha glucosidase inhibitor and its correlation to total phenolic content. 2. experimental section 2.1 materials the p speciosa was collected at ogan komering ulu district, south sumatera. chemical material for this research are pnitrophenyl-α-d-glucopiranoside (pnpg), enzyme α-glucosidase and bovin serum albumin (bsa) from sigma-aldrich, potashttps://doi.org/10.26554/sti.2019.4.1.1-4 fitrya et. al. science and technology indonesia, 4 (2019) 1-4 sium carbonate (merck®), �lter paper , bu�er solution ph 6,8, dimetylsulfokside (dmso) (merck®), folin ciocalteu reagent (merck®) and acarbose (glukobay®)(bayer schering pharma) 2.2 methods 2.2.1 preparation of extract the material for this research included leaf, seed and rind of p speciosa. preparation of sample start from washing, drying and powdering. dried powder (500 g) extracted with 3 l ethanol 96% for 48 h by maceration method. maceration process repeated for twice. macerate were �ltered through �lter paper and concentrated by rotary evaporator. 2.2.2 inhibitory activity of alpha glucosidase test inhibitory activity test was carried out according to standard method by slight modi�cation (telagari and hullatti, 2015; kaskoos, 2013; najib et al., 2011). each sample test was determined by adding 55 µl phosphate bu�er ph 6,8 and 10 µl substrate pnpg 10 mm, incubated at 37°c for 5 min. furthermore, 25 µl enzyme solution 0,05 u/ml and incubated for 30 minutes at 37°c. sodium carbonate 200 mm (100 µl) was added to stop reaction. absorbance of sample measured using microplate reader at 405 nm. the same procedure was done for control sample but enzyme added after sodium carbonate. percentage of inhibitory activity was determined : %inhibition = a0 − a1 a0 x100% (1) which, a0= absorbance of blank; a1 = absorbance of sample the ic50 value calculated by linear regression between sample concentration and percent of inhibition ic50 = 50 − a b (2) 2.2.3 determining the total phenolic content (tpc) the total phenolic content of extract was determined by standard method. the ethanol extract of leaf, seed and rind of p speciosa (10 mg) dissolved in 0,5 ml ethanol, diluted with aquadest to 10 ml. this fraction (1ml) added 1,5 ml folin reagent and shaked and then keep it motionless for 8 minutes. each of solution added 1,2 ml na2co3 7,5% and absorbance recorded at 765 nm. the total phenolic content of extract expressed as mg gallic acid equivalent /g extract and calculated by formula: tpc = c.v.f p g (3) which, c = phenolic concentration from linear regression; v = volume of extract; fp = dilution factor; g = weight of extract 3. results and discussion 3.1 characterization of extract phytochemicals screening was done by standard method on leaf, seed and rind of p speciosa. the test was included identi�cation of phenolic, �avonoid and steroid. the result of screening showed at table 1. table 1. phytocemicals screening of parkia speciosa hassk secondary metabolite reagent rind leaf seed flavonoid mg+hcl 2n + naoh 2n + + + phenolic fecl3 0,1% + + + steroid liebermen-buchard + + + characterization of extract was done according to standard method (depkes ri., 2008). the characterization of the extract aims to maintain the consistency and uniformity of the extract quality. evaluation of characteristic of ethanol extract was done by assessing water content, total ash content, water soluble content, ethanol soluble content. the result for characterization of extract showed in table 2. the result showed that the seed have the highest of water content. it could be caused by maturation hormone of seed that increase the water content of the seed, whereas in the rind the moisture content is lower because the water content of the rind migrates into the seeds to increase the maturity of the seed (ridhyanty et al., 2015). the rind of p speciosa has high ash content compared to seeds and leaf. this may be due to the growing sample in the garden close to the smoke of the vehicle causing the rind exposed to smoke of vehicles containing metals. high ash content may be a�ected by seed variables, growing spots, climate, harvest conditions, post-harvest processing and �nal preparations such as drying and sieving (mutiatikum et al., 2010). the rind and leaf of pspeciosa have higher content of ethanol soluble than in water soluble, whereas in the seed has the opposite result. this suggests that the content of polar compounds in the seeds is higher than semi polar compounds . the seeds have more polar compound content can be caused due to high carbohydrate levels. this can be linked because water molecules can form hydrates with other molecules containing o and n atoms common to carbohydrates and proteins (fg, 2002). 3.2 total phenolic content the total phenolic content (tpc) of leaf, seed and rind of p speciosa was determined with folin ciocalteu reagent. standard solution was gallic acid and absorbance was measured at 765 nm (paixao et al., 2007). regression formula obtained y = 0,008x + 0,021 (r = 0,998). the tpc from our research have di�erence with other researchers (kamisah et al., 2013). the previous researchers showed that the ethanol extract of leaf have tpc 44,7 mggae/g and the seed extract was 51,9 mggae/g (kamisah et al., 2013). our research showed the tpc of rind, leaf and seed were 138,15; 59,25; 36,25 mggae/g respectively. the di�erence of quality and quantity of plant chemical content could be caused di�erences of habitats and post harvest processing (mulia et al., 2016). © 2019 the authors. page 2 of 4 fitrya et. al. science and technology indonesia, 4 (2019) 1-4 table 2. characteristic of parkia speciosa extract characteristic extract rind leaf seed water content 18,67% ± 3,055 20% ± 0 22,67% ± 2,309 total ash content 20,6%± 0,0005 9,6%± 0,0037 3,3%± 0,0005 water soluble content 15,29%± 0,0234 20,29%± 0,0218 4,6%± 0,0047 ethanol soluble content 22,7%± 0,0233 4,4%± 0,032 21,3%± 0,0288 3.3 alpha glucosidase inhibitory test the e�ectiveness of enzymatic of various extract was determined by calculating ic50 21. alpha glucosidase inhibitory activity test was done to ethanol extract of leaf, seed and rind of p speciosa. optimum condition for enzyme activity on temperature 37°c , concentration of enzyme 0,05 u/ml, and concentration of substrate 10 mm, ph 6,8 (najib et al., 2011). optimum incubation time for reaction reached by two step. first incubation was 5 minutes at 37°c, it was for reached optimum condition for reaction. the second incubation for 30 minutes was time for bonding between enzyme with all of substrate. enzyme interaction became e�ective if ph of solution as same as intestine. the research showed that the rind of p speciosa was the highest inhibition activity with ic50 4,5968. ic50 value of each extract and acarbose showed at table 3. ic50 value of extract smaller than acarbose, it was indicated that capacity of extract to inhibit of enzyme greater than acarbose.the lower value of ic50 showed that the higher enzymatic inhibition (zhang et al., 2015) table 3. the ic50 value of extract and acarbose sample ic50(ppm) tpc (mggae/g) rind 4,596 138,15 leaf 54,341 59,25 seed 67,425 36,25 acarbose 162,508 based on tpc and inhibitory activity data, the highest value of test showed by rind of p speciosa. there was correlation between tpc and antidiabetic activity. phenolic compound has capacity as inhibitor of alpha glucosidase activity by bonding with site active of protein (schafer and p, 2006). alpha glucosidase inhibitory activity result in postponement of carbohydrate hydrolysis, it was cause reduction of postprandial hyperglycemic (adisakwattana et al., 2007). correlation analysis between tpc and ic50 value showed that correlation value was -0,998. coe�cient correlation value approach to 1, that mean two variable have good correlation each other and negative value denotes that decrease in the ic50 in proportion to the increase in total phenolic content. it can be concluded that tpc of p speciosa be responsible to alpha glucosidase inhibitory activity. 4. conclusions based on research, it can be concluded that ic50 value of alpha glucosidase inhibitory activity of rind, leaf and seed were 4,596 ppm, 54,341 ppm and 67,425 ppm. these activity be connected to total phenolic content of extract. greater of tpc would be more active of extract. total phenolic content of rind, leaf and seed extract were 138,15 mggae/g, 59,25 mggae/g and 36,25 mggae/g. 5. acknowledgement we gratefully acknowledge the support “lembaga penelitian dan pengabdian pada masyarakat”, sriwijaya university, sponsored by “penelitian sains teknologi dan seni,” and ministry of research technology and higher education, indonesia. references adisakwattana, s., c. p, and y. anun s (2007). a-glucosidase inhibitory activity of cyanidin-3-galactoside and synergistic e�ect with acarbose. journal of enzyme inhibition and medicinal chemistry, 24(1); 65–69 ali, m., v. c, and i. d (2011). antioxidant capacities of vegetables consumed in north east india assessed by three di�erent in vitro assays. international research journal of pharmacy, 2(2); 118—123 azliza, m., o. hc, v. s, n. a, and h. nw (2012). ethnomedicinal resources used by the temuan in ulu kuang village. ethno medicine, 6(1); 17–22 bhat, m., z. ss, b. sy, k. ar, and j. bn (2011). antidiabetic indian plants: a good source of potent amylase inhibitors. evidence based complement alternate medicine chen, j., w. y, l. jt, d. dd, miller, and l. w (2008). synthesis and antiproliferative activity of imidazole and imidazoline analogs for melanoma. bioorganic and medicinal chemistry letters, 18(11); 3183–3187 fg, w. (2002). kimia pangan dan gizi. gramedia pustaka utama, jakarta idf (2017). diabetes atlas edition 7th. http://www.diabetesatlas.org/ kamisah, y., o. f, q. ms, and j. k (2013). parkia speciosa hassk: a potential phytomedicine. evidence-basedcomplement and alternative medicine © 2019 the authors. page 3 of 4 fitrya et. al. science and technology indonesia, 4 (2019) 1-4 kaskoos, r. (2013). in-vitro a-glucosidase inhibition and antioxidant activity of methanolic extract of centaurea calcitrapa from iraq. american journal of essential oil and natural product, 1(1); 122–125 kim, y., j. yk, w. mh, l. wy, and r. h (2005). inhibitor effect of �ne extract on a-glukosidase activity and postprandial hyperglycemia. nutrition, 21(1); 756–761 mulia, k., h. aez, and s. s (2016). total phenolic, anticancer and antioxidant activity of ethanol extract of piper crocatum vahl from pamekasan and karang asem. current biochemistry, 3(2); 80–90 mutiatikum, d., a. s, and a. y (2010). standardisasi simplisia dari buah miana (plectranthus seutellaroides (l) r. bth) yang berasal dari 3 tempat tumbuh menado, kupang dan papua. buletin penelitian kesehatan, 38(1); 1–16 najib, a., h. s, and e. b (2011). in vitro bioassay of n-buthanol isolate of acorus calamus l. on inhibitory of activity aglucosidase. international journal pharmacy technology res, 4(3); 2085–2088 paixao, n., p. r, m. jc, and c. js (2007). relationship between antioxidant capacity and total phenolic content of red, rose and white wines. food chemistry, 105(1); 204–214 qaisar, m., b. ac, m. us, and n. h (2014). evaluation of a-glucosidase inhibitory activity of dichloromethane and methanol extracts of croton bonplandianum baill. tropical journal of pharmaceutical research, 13(11); 1833–1836 ridhyanty, s., j. e, and l. lm (2015). e�ect of ethepon as ripening stimulant on the quality of barangan banana (musa paradisiaca l) fruit. jurnal rekayasa pangan dan pertanian, 3(1); 1–13 schafer, a. and h. p (2006). oligomeric procyanidins of french maritime pine bark extract (pycnogenol) e�ectively inhibit a-glucosidase. diabetes research and clinical practice, 77(1); 41–46 si, m., l. j, z. c, and w. h (2010). insulin releasing and alpha-glucosidase inhibitory activity of ethyl acetate fraction of acorus calamus in vitro and in vivo. journal ethnophar, 128; 154–159 telagari, m. and k. hullatti (2015). in-vitro a-amylase and aglucosidase inhibitory activity of adiantum caudatum linn. and celosia argentea linn. extracts and fractions indian journal of pharmacology, 47(4); 425–429 zhang, h., g. wang, b. t, and d. j (2015). inhibitory properties of aqueous ethanol extracts of propolis on alphaglucosidase. evidence-based complementary and alternative medicine © 2019 the authors. page 4 of 4 introduction experimental section materials methods preparation of extract inhibitory activity of alpha glucosidase test determining the total phenolic content (tpc) results and discussion characterization of extract total phenolic content alpha glucosidase inhibitory test conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 research paper cytotoxic activity of tahongai (kleinhovia hospita linn.) leaves extracts using brine shrimp lethality test indah solihah1*, herlina1, khairunnisa1, riana sari puspita rasyid2, tri suciati2 1faculty of mathematics and natural sciences, sriwijaya university, ogan ilir 30662, south sumatera, indonesia 2faculty of medicine, sriwijaya university, ogan ilir 30662, south sumatera, indonesia. *corresponding author: indahsolihah26614@gmail.com abstract tahongai (kleinhovia hospita linn.) leaves had been known contain alkaloids, flavonoids, saponins, steroids, and tannins. at komering, south sumatera province, tahongai leaves had been known to treat tumor, cancer, polyps, acne, and dysmenorrhea. the study of cytotoxic activity of tahongai bark and stem were done. this study aims to determine the cytotoxic activity of tahongai leaves extracts using bslt method. tahongai leaves were extracted using gradual maceration with n-hexane, ethyl acetate, and ethanol 96%. each extract was tested cytotoxic activity towards artemia salina l. larvae. the yield of n-hexane, ethyl acetate, and ethanol extracts are 2,686%, 7,033%, and 7,933% respectively. ethanol extract of tahongai leaves had the best cytotoxic activity with lethality value 76,667% at 500ppm. statistical analysis with two way anova showed extract and concentration had a significant (p<0,05) e�ect on larvae lethality percentage. keywords kleinhovia hospita linn., artemia salina l., cytotoxic, bslt. received: 4 june 209, accepted: 17 july 2019 https://doi.org/10.26554/sti.2019.4.3.60-63 1. introduction tahongai (kleinhovia hospita linn.) is a tropical plant. tahongai has a therapeutic e�ect as antidiabetic, antioxidant, hepatoprotective, anticancer, and antihyperlipidemic (paramita, 2016). research on cytotoxic e�ects of tahongai plant has been carried out by morilla et al. (2015) using bark and stem ethanol extract with an lc50 value 452,03 �g/ml. methanol extract of tahongai leaves, stem, and bark had been studied to have cytotoxic activity in hepatoma cells and can inhibit murine leukemia cells (p388) with iic50 56 �g/ml (nurhidayah et al., 2013). decoct of tahongai bark and stem also have cytotoxic activity with an lc50 value of 698.54 �g/ml morilla et al. (2015). the leaves and wood of kleinhovia hospita linn. found to contain �avonols, kaempferol, and quercetin (arung et al., 2012).pieme et al. (2010) found that quercetin and kaempferol had anticancer activity. quercetin and kaempferol are one of the compounds of �avonoid that have anticancer e�ects both in vitro and in vivo test (baghel et al., 2012). based on the study above, in this study, gradual maceration was carried out to obtain active compounds from various polarity levels using n-hexane (nonpolar), ethyl acetate (semi-polar) and ethanol (polar) solvents. each extract was done to compare the cytotoxic activity using brine shrimp lethality test (bslt). 2. experimental section 2.1 materials plant materials used for this study comes from the same source used by solihah et al., (2018). the chemicals used of this study were n-hexane (brataco®), ethyl acetate (brataco®), ethanol (brataco®), aquadest (brataco®), mayer reagent (merck®), wagner reagent (merck®), dragendor� reagent (merck®), sulfuric acid (merck®), ammonia (merck®), chloroform (merck®), hydrochloric acid (merck®), magnesium powder (merck®), sodium hydroxide (merck®), iron (iii) chloride (merck®), anhydrous acetic acid (merck®), dmso (merck®), quercetin (fitopure®), kaempferol (fitopure®), and shrimp larvae artemia salina leach (supreme®). 2.2 instruments the instruments used for this study are blender (philips®), rotary evaporator (ika-c mag®), maceration chamber, water bath (memmert™), glass tools (pyrex®), silica tlc plate g60 f254 (merck®), vaporizer plate (rrc®), micropipette (dragon lab®), vortex (corning lsetm), 40-60 w (itsuyama®) lighting, analytical scale of readability 0,01 and 0,0001 g (electronic scale® and ohaus®), magnetic stirrer (ika c-mag®). https://doi.org/10.26554/sti.2019.4.3.60-63 solihah et. al. science and technology indonesia, 4 (2019) 60-63 2.3 extraction a total of 1 kg dried leaves of tahongai were soaked with 6 l n-hexane where every two days the solvent was replaced until clear about ten days. powdered pulp was macerated with 6 l ethyl acetate solvent and 6 l 96% ethanol using the same method. filtrate evaporated using a rotary evaporator to obtain a thick extract. 2.4 phytochemical screening 2.4.1 flavonoid identi�cation the extracts of 0,5 g were added with 5 ml of hot ethanol for 5 minutes. the extract are �ltered so that the �ltrate was obtained and then a few drops of concentrated hcl are added, and 0,2 mg of magnesium powder was added. the red color indicates the presence of �avonoid group compounds. 2.4.2 saponin identi�cation the extracts of 1 g were added with distilled water and boiled for 2 minutes and shaken vigorously. the existence of saponins was characterized by the formation of a stable foam in a test tube. 2.4.3 alkaloids identi�cation the extracts of 2 g were taken then a little chloroform and sand were added and ammonia in chloroform. the mixture was shaken and then �ltered. the �ltrate was added with h2so4 2n and then shaken. two layers were formed. the top layer in the form of a water phase was separated and then tested by mayer, wagner, and dragendor� reagents. the presence of alkaloids was characterized by red sediment with wagner reagents, white sediment with mayer reagents, and red or orange color with dragendor� reagent (al-daihan and bhat, 2012). 2.4.4 steroids and triterpenoids identi�cation the bottom layer from alkaloid identi�cation was separated and dropped onto the drop plate, allowed to dry. anhydrous acetic acid was two drops, and one drop of concentrated sulfuric acid (lieberman-buchard reagent) was added to the residual. the green or red color formed indicates the presence of steroid or triterpenoid compounds (al-daihan and bhat, 2012). 2.4.5 identi�cation of tannins an amount of 2 g tahongai leaves extracts were added with 100 ml of water then boiled for 15 minutes then cooled and �ltered so that �ltrate was obtained. an amount of 1% iron (iii) chloride solution was added to the �ltrate. the presence of tannin compounds was characterized by the formation of dark blue or blackish green (al-daihan and bhat, 2012). 2.5 identi�cation of quercetin and kaempferol using tlc identi�cation of quercetin compounds on tahongai (kleinhovia hospita linn.) leaves extracts using tlc method. tlc plates were measured at 6 x 10 cm2 with the upper and lower limits of 1 cm. tahongai leaves extracts, quercetin, and kaempferol were made at a concentration of 5% and then dripped along with the silica tlc plate g60 f254. the tlc plate was eluted using chloroform : ethyl acetate (5:2) eluent. comparison of eluents was obtained from the results of the experiment. the tlc results were aerated and detected under uv light at a wavelength of 254 and 366 nm. then sprayed with 5% aluminum (iii) chloride spray reagent in ethanol (colegate and russel, 1993). results of tlc were stains or spots that glow greenish-yellow (nuria et al., 2011). 2.6 cytotoxic activity test 2.6.1 preparation of stock solution each tahongai leaves extracts were dissolved in 4 drops of dmso 10%, and 1000 ppm (mother liquor) concentration was made then a test solution with a concentration of 500; 250; 125; 62,5; and 31,25 ppm. dmso 10% control solution was used without the addition of extracts (morilla et al., 2015). 2.6.2 preparation of artemia salina leach larvae an amount of 1 l of arti�cial seawater (20 g of salt in 1 l of water) was needed for 1 g of artemia salina leach. eggs. artemia salina leach. egg put into a hatchery that has contained seawater or synthetic seawater then illuminated with a 40 – 60 w lamp for 24 – 48 hours. eggs that have hatched into larvae were moved to another place, and 24 hours later, the larvae were used as test subjects (morilla et al., 2015). 2.6.3 cytotoxic test six pieces of vials were used in testing each variation of the extract, which was divided into �ve vials for each test concentration and one vial for control. each concentration was taken according to the calculation while for the negative control, 5 ml of seawater was added. a total of 10 larvae of artemia salina leach. the larvae put into seawater, which has been mixed with the test solution. observations were made for 24 hours (lisdawati et al., 2016). 2.7 statistical analysis the data of percentage of larvae lethality are expressed as the mean ± sd. percentage of larvae lethality used as a dependent factor, whereas the type of extract and concentration used as an independent factor. the di�erence among the means has been analyzed by two way anova. 3. results and discussion 3.1 extraction and phytochemical screening results extraction of tahongai leaves by gradual maceration method using n-hexane, ethyl acetate, and ethanol 96%. the yield of extracts can be seen in table 1. table 1. the yield of extracts extract total (g) % yield n-hexane 26,86 g 2686% ethyl acetate 70,33 g 7033% ethanol 79,330 g 7933% © 2019 the authors. page 61 of 63 solihah et. al. science and technology indonesia, 4 (2019) 60-63 yield states the percentage of raw material obtained from the total raw material in the extraction process. the higher the yield value, more the opportunity for the raw material to be utilized. percent of yield can be in�uenced by the duration of extraction time and the degree of �neness of the simplicia particle size. each extract was macerated for ten days. the smaller the size of the simplicia, the higher the surface area of the particles so that the solvent is more attract compounds in the sample but if the simplicia powder is too �ne, it can broken cell walls and unwanted substances (ballasts) will enter the maceration results. this is not desirable in the extraction process. the percentage of yield obtained showed that ethanol extract had the highest percentage of yield compared to other extracts of 7,933%. ethanol as a polar solvent, which can attract polar components. this is indicates that the most polar component was found in tahongai leaves so the percentage of yield highest than another. phytochemical screening is an examination of the chemical content qualitatively to ensure the presence of the desired secondary metabolites contains in plant or extract. the data reveal the presence of various constituents in each extract. phytochemical test results can be seen in table 2. table 2. phytochemicals screening test of tahongai leaves extracts chemical screening result of extracts substance n-hexane ethyl acetate ethanol alkaloid + + + flavonoid + + saponin + + tanin + + triterpenoid steroid + + + all tahongai leaves extracts do not contain triterpenoids. nhexane extract only contains alkaloid and steroid compounds. while ethyl acetate and ethanol extracts contain alkaloids, �avonoids, tannins, saponins, and steroids. 3.2 identi�cation of quercetin and kaempferol with tlc identi�cation of quercetin and kaempferol in tahongai leaves extracts was used thin-layer chromatography. stationary phase used was silica while the mobile phase used is chloroform: ethyl acetate (5:2). spots produced by each component were observed in uv light 254 nm and uv 366 nm. uv light 254 shows that the compound has at least two conjugated double bonds while the �uorescence under uv light 365 nm shows that the component has a chromophore and has an auxochrome group in its structure (alen et al., 2017). klt plate was sprayed with aluminum (iii) chloride (alcl3) reagent. the resulting color shows a yellow color. the results showed in �gure 1. quercetin and kaempferol compounds based on the results of tlc testing contained in ethyl acetate and ethanol extract. quercetin and kaempferol are both polyhydroxy �avonol comfigure 1. the chromatogram of tahongai leaves extracts (k = kaempferol; q = quercetin; 1 = n-hexane extract; 2 = ethyl acetate extract; 3 = ethanol extract) (a) under uv light 366 nm (b) under uv light 254 nm (c) sprayed with alcl3 pounds. leaves of kleinhovia hospita l. had been reported contains scopoletin, kaempferol, quercetin, eleutherol and kaempferol 3-o-b-d glucoside compounds (arung et al., 2012) 3.3 cytotoxic activity the test of cytotoxic activity of tahongai leaves extracts were used bslt (brine shrimp lethality test) method. the cytotoxic e�ect of tahongai leaves extracts was determined within 24 hours after administering each extract with various concentration using artemia salina as a test subject. each test was carried out on 10 larvae then replicated 3 times. results obtained are calculated as the percentage value. based on the data in table 3 it can be seen that the higher concentration of extract can cause the mortality of the larvae was greater. while the extract which has the most potential as a cytotoxic agent was the ethanol extract of tahongai leaves. in the ethanol extract of tahongai leaves contained polar compounds, such as polyhydroxy �avonoids. the mechanism of larvae lethality of artemia salina l is estimated to be related to the compounds contained in tahongai leaves extract such as �avonoids as cytotoxic agents. from the results of phytochemical screening showed that ethyl acetate and ethanol extract contained �avonoids while �avonoids were not found in n-hexane extract. flavonoids at certain levels have the potential for acute toxicity (carballo et al., 2002). the presence of �avonoids in the cell environment causes hydroxy groups in �avonoids to bind to cell membrane integral proteins. this causes the blocking of the active transports na+ and k+, the active transport stops, causing uncontrolled inclusion of na+ ions into the cell. this causes the rupture of cell membranes (scheuer, 2004). rupture of cell membranes causes cell death. data analysis was used two way anova method. two way anova was conducted to test the di�erences in several groups based on two independent variables. data on percent lethality of larvae as a dependent factor, while the type and concentration of extracts as an independent factor. data is declared homogeneous if the signi�cance value is ≥ 0,05. the homogeneity value obtained is 0,238 (p> 0,05) so the data has the same variation. © 2019 the authors. page 62 of 63 solihah et. al. science and technology indonesia, 4 (2019) 60-63 table 3. the e�ect of tahongai leaves extract in larvae lethality concentration larvae lethality (mean ± sd) (%) (ppm) n-hexane ethyl acetate ethanol 31,25 6,667±0,577 13,333±1,155 16,667±0,577 62,5 13,333±0,577 30,000±1,000 40,000±1,000 125 16,667±0,577 43,333±0,577 56,667±0,577 250 23,333±0,577 53,333±0,577 70,000±0,000 500 26,667±0,577 66,667±0,577 76,667±0,577 at anova values, there was type of extract variable, concentrations, and type of extract-concentration interactions. if the signi�cance value is <0.05, the data is signi�cant. the value obtained is a correction model of 0,000 the data is signi�cantly di�erent. the signi�cance of type of extract, concentration, and type of extract-concentration interaction variables was 0,000 (p <0,05). this states that type of extracts, concentrations, and interactions between type of extracts and concentrations have a signi�cant e�ect on percent lethality of artemia salina l. larvae. 4. conclusions based on the results of this study, it can be concluded that the ethanol extract of tahongai leaves has the greatest yield and contain the greatest phytochemical groups compound. this correlates with its activity as a cytotoxic agent. tahongai leaves ethanol extract has the largest cytotoxic activity compared to n-hexane and ethyl acetate extract. 5. acknowledgement authors would like to express their gratitude toward sriwijaya university pnbp sateks research grant that made this research possible. references al-daihan, s. and r. bhat (2012). antibacterial activities of extracts of leaf, fruit, seed, and bark of phoenix dactylifera. afr j biotechnology, 11(42); 10021–10025 alen, y., f. agresa, and y. yuliandra (2017). thin-layer chromatography (tlc) analysis and antihiperuricemia activity of schizostachyum brachycladum kurz (kurz) bamboo shoot extract in male white mice. j of sains & clinical pharm, 3(2); 146 – 152 arung, e., i. kusuma, s. purwatiningsih, s. roh, c. yang, and s. jeon (2012). antioxidant activity and cytotoxicity of the traditional indonesian medicine tahongai (kleinhovia hospita l.) extract. j acupunct meridian stud, 2(4); 306–308 baghel, s., n. shrivastava, r. baghel, p. agrawal, and s. rajput (2012). a review of quercetin: antioxidant and anticancer properties. world j pharm pharmaceut sci, 1(2); 146–160 carballo, j., z. inda, p. perez, and m. gravalos (2002). a comparison between two brine shrimp assays to detect in vitro cytotoxicity in marine natural products. bmc biotechnology, 2(17); 1–5 lisdawati, v., s. wiryowidago, and l. kardono (2016). brine shrimp lethality test (bslt) of various fractions of fruit �esh and seed skin mahkota dewa (phaleria macrocarpa). medical res bulletin, 34(3); 111-118 morilla, l., o. nuñeza, and m. uy (2015). brine shrimp lethality test of kleinhovia hospita stem and bark from agusan del sur. elba bio�ux, 7(1); 61-66 nurhidayah, n., m. minarti, a. pratama, and i. imran (2013). test the activity of terpenoid steroid and phenolic derivative compounds from extracts of stem tissue from ndokulo (kleinhovia hospita l.) plants to cancer cell growth (leukemia p-388). proceeding pimnas pkm-p, kendari, indonesia nuria, m., wahyono, and r. susidarti (2011). identi�cation of kaempferol from jangkang leaves (homalocladium platycladum (f.muell) bailey) and their antibacterial activity. indonesian journal of pharmacy, 22(1); 1–8 paramita, s. (2016). tahongai (kleinhovia hospita l.): a review of herbal medicine from east kalimantan. science, 9(1); 29–35 pieme, c., v. penlap, j. ngogang, and m. costache (2010). in vitro and antioxidant activities of �ve medicinal plants of malvaceae family from cameroon. environmental toxicology and pharmacology, 29; 223-228 scheuer, p. (2004). ciguatera and its o�shoots: encounters en route to a molecular structure. tetrahedron, 50; 3-18 © 2019 the authors. page 63 of 63 introduction experimental section materials instruments extraction phytochemical screening flavonoid identification saponin identification alkaloids identification steroids and triterpenoids identification identification of tannins identification of quercetin and kaempferol using tlc cytotoxic activity test preparation of stock solution preparation of artemia salina leach larvae cytotoxic test statistical analysis results and discussion extraction and phytochemical screening results identification of quercetin and kaempferol with tlc cytotoxic activity conclusions acknowledgement science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 17-21 article http://sciencetechindonesia.com @2017 published under the terms of the cc by nc sa 4.0 license 17 adsorption of congo red using mg/al hydrotalcite muhammad said1, neza rahayu palapa1* 1department of chemistry, faculty of mathematics and natural science, sriwijaya university *corresponding author e-mail: nezarahayu@gmail.com abstract mg/al hydrotalcite and mg/al hydrotalcite intercalated with polyoxometalate h4[α-siw12o40].nh2o (1:1) was synthesized and used as adsorbent colored-dye i.e. congo red. adsorption was conducted using batch system. the factor that influencing adsorption such as kinetic, thermodynamic, and ph was investigated. the results showed that kinetically adsorption of mg/al intercalated polyoxometalate was faster than mg/al hydrotalcite before intercalation. on the other side, thermodynamically adsorption using mg/al hydrotalcite is higher than mg/al hydrotalcite intercalated polyoxometalate. probably due to high molecular size of congo red can decresed the adsorption ability of mg/al hydrotalcite after intercalated. keywords: hydrotalcite, polyoxometalate, intercalated, congo red, adsorption introduction hydrotalcite has general formula [m2+(1-x)m3+x(oh)2](an)x/nh2o. this layer materials contains divalent and trivalent matal cation with high flexibility cation exchange and esily synthesized in laboratory (zhao, et.al, 2011). application of hydrotalcite can be achived optimally by modification of these material. the modification of hydotalcite for various applications is interesting due to ion exchange ability such as sensors, membranes, adsorbents, catalysts, and ion exchanges (duan et.al, 2011). modification of hydrotalcite can be achived by intercalation using anion such as sulfate, carbonate, or nitrate. these anions are cations with small size (asif et.al, 2017). in order to increase the ability of hydrotalcite as adsorbent, the use of macroanion is vital. macroanions are rarely obtained in the nature or laboratory. thus synthesis of macroanions for intercalant of hydrotalcite is intriguing research. lesbani et.al (2008, 2015) was used polyoxometalates as macroanion for starting materials of ionic cystals and as catalysts. the advantages of polyoxometalate are high acidity, redox properties, high solubility depanding on counter ions, and various structures such as keggin, dawson, anderson, and lacunary types. among these polyoxometalates, keggin type is commonly used in many applications due to stability of these compound. polyoxometalates were applied as intercalant in many layer double hydroxides materials like hydrotalcite (jia et.al, 2015, liu et.al, 2016). in this research, hydrotalcite and hydrotalcite intercalated keggin type polyoxometalate of h4[αsiw12 o40].nh2o was used as adsorbent of congo red. in the previous research, optimization of intercalation process of hydrotalcite was conducted using polyoxometalate h4[αsiw12 o40].nh2o (palapa and said, 2016). congo red is an anionic azo dye having iupac article history received: 25 septermber 2016 accepted: 14 december 2016 doi: 10.26554/sti.2017.2.1.17-21 name as 1-napthalesulfonic acid, 3, 3-[4,4-biphenylebis(azo)] bis (4-amino disodium) salt (bhoi, 2010). the adsorption process of hydro talcite intercalated polyoxometalate h4[αsiw12o40].nh2o is intended to determine the effect of ph, kinetic, and thermodynamic parameters by measuring residual concentration and adsorbed amount using uv-vis spectrophotometer. experimental section materials the chemicals used are qualified materials such as sodium metasilicate, sodium tungstate, hydrochloric acid, potassium hydroxide, potassium chloride, diethyl ether, sodium hydroxide, sodium carbonate, magnesium nitrate, congo red dye and aquadest. methods synthesis of hydrotalcite, polyoxometalate h4[αsiw12o40]•nh2o, and hydrotalcite intercalated h4[αsiw12o40]•nh2o has been reported previously (palapa and said, 2016). application of hydrotalcite intercalated by polyoxometalate h4[α-siw12o40]•nh2o as adsorbent of congo red dye 1. ph ph reaction of congo red adsorption on hydrotalcite intercalated was studied by varying the initial ph of congo red solution. 0,1 g of hydrotalcite and hydrotalcite intercalated each added into 50 ml of congo red dye solution 50 mg/l shaker until 10 minutes using a horizontal shaker. the initial ph of congo red was set at 3, 4, 5, 6, 7, 8, 9 and 11 with the addition of 0,1 m naoh and 0,1 m hcl. then the congo red was separated and the residual concentration after the adsorption process was measured using a uv-visible spectrophotometer. 2. kinetic 0,1 g of hydrotalcite and hydrotalcite intercalate each added into 50 ml of congo red dye solution 50 mg/l shaker with variations in absorption time varied start from 10, 20, 30, 40, 50, said et al. / science and technology indonesia 2(1) 2016:17-21 @2017 published under the terms of the cc by nc sa 4.0 license 18 60, 70, 80, 90, 100, 110 and 120 minutes using a horizontal shaker. the solution of the adsorbed congo red dye substance was separated by filtration and then measured its concentration by using uv-vis spectrophotometer. the adsorption rate can be calculated using the langmuir equation 1. 3. thermodinamic thermodynamic adsorption of the congo red dye into hydrotalcite and hydrotalcite intercalated of experiment series as carried out through a series of experiments by varying the concentration and the adsorption temperature. 0,1 g hydrotalcite intercalated by polyoxometalate added 50 ml of congo red dye solution varied concentration 50, 60, 70, 80 and 90 mg/l while stirred using a horizontal shaker for 30 min at varying temperatures 30, 40, 50, 60 and 70oc. as the control, in different containers as much as 0,1 g of hydrotalcite added into 50 ml congo red dye solution varied of concentration 10, 20, 30, 40 and 50 mg/l. the solution was filtered and congo red separated from the adsorbent was measured using a uv-visible spectrophotometer. data analysis hydrotalcite and hydrotalcite intercalated by polyoxometalate were characterizations using ft-ir, xrd, and tg-dta. the result was applied as adsorbent congo red dye. the adsorption process was studied by the kinetic and thermodynamic parameter. the kinetics of adsorption was studied by variated of time and adsorption rate was calculated with langmuir equation: ln( 𝐶0 𝐶 ) 𝐶 = 𝑘1 𝑡 𝐶 + k (1) where : c0 = initial concentration of congo red c = concentration of congo red after the time t = time of adsorption k = the adsorption equilibrium constant thermodinamic parameters was studied by varied of concentration congo red dye, adsorption capacity and adsorption energy calculated using langmuir eq: 𝐶 𝑚 = 1 𝑏𝐾 + 𝐶 𝑏 (2) e = rt ln k (3) where : c = the congo red concentration after adsorption reaches equilibrium m = mol of congo red adsorption 0,1 g hydrotalcite k = equilibrium constant b = adsorption capacity e = adsorption energy r = boltzmann constant t = temperature whereas to find the coefficient value of adsorbat ditribution is used the equation: ln kd = ∆𝑆 r − ∆h 𝑅𝑇 (4) where : kd = coefficient ditribution adsortion find the coefficient value of adsorbat ditribution (qe/ce) δh = enthalphy δs = enthrophy r = boltzmann constant t = temperature the bonds formed between the adsorbate and the adsorbent was studied by ft-ir spectrophotometer. results and discussion characterization of intercalated layered double hydroxide with h4[αsiw12 o40].nh2o was presented by palapa and said (2016) in previous published article. in this results, adsorption of congo red process was systematically reported. effect of initial ph adsorption of congo red dye by hydrotalcite mg/al intercalated polyoxometalate h4[α-siw12o40]•nh2o ph adsorption of hydrotalcite and hydrotalcite intercalated to congo red is shown in figure 1. hydrotalcite has optimal ph at ph 9 with adsorbed concentration of 48,893 ppm with addition of 0.05 ml of hydrochloric acid. the insertionn double layer hydroxyl has an optimum ph at ph 8 with an adsorbed concentration of 47.529 ppm with addition of 0.10 ml of sodium hydroxide. previously controls for congo red dyes without adsorbents showed that congo red to become unstable due to the influence of ph, this is indicated by the color change in congo red. figure 1. effect of adsorption ph of hydrotalcite and hydrtalcite intercalated amount of adsorbed congo red effect of congo red adsorption of time by hydrotalcite and hydrotalcite intercalated hydrotalcite intercalated can absorb more adsorbate than hydrotalcite at the same time. at the optimum time of adsorption at 70 min it is seen that the amount of congo red dye 0.000 20.000 40.000 60.000 80.000 0 5 10 15 c o n ce n tr a ti o n ph said et al. / science and technology indonesia 2(1) 2016:17-21 @2017 published under the terms of the cc by nc sa 4.0 license 19 stuff adsorbed by 1.5 times the adsorbent without insertion process. this is because the hydrotalcite intercalated has a larger basal spacing of 9.81 ȧ than the previous value of 7.4 ȧ. the hydrotalcite intercalated and hydrotalcite curves before the insertion process are presented in figure 2. the data obtained in table 1 show that the hydrotalcite intercalated adsorbent has a higher adsorption rate than the hydrotalcite before intercalated it causes the hydrotalcite intercalated adsorbent to have a greater reactive rate than the hydrotalcite before intercalated. figure 2. effect of congo red adsorption of time by hydrotalcite and hydrotalcite intercalated table 1. adsorption rate values for hydrotalcite and hydrotalcite intercalated adsorbent parameter k1 (sec-1) r2 hydrotalcite 13,64 0,984 hydrotalcite intercalated 51,38 0,999 effect of concentration and temperature adsorption congo red dye by hydrotalcite and hydrotalcite intercalated adsorption temperature data by hydrotalcite adsorbent and hydrotalcite intercalated figures 3 and 4 show the results of the effect of adsorption temperature on the adsorbed congo red amount of hydrotalcite adsorbent and the hydrotalcite intercalated. figures 3 and 4 show the effect of temperature and concentration of congo red dye by a hydrotalcite adsorbent and hydrotalcite intercalated shows that the larger the temperature the greater the amount of adsorbed congo red, the greater the concentration then the amount of congo red adsorbed will increase as well hydrotalcite adsorbent (control) presented in figure 3. the adsorption capacity and adsorption energy of the congo red dye adsorption process by hydrotalcite and the hydrotalcite intercalated table 2 explains that the adsorption energy value (e) of congo red adsorption by hydrotalcite intercalated at visible concentration variations the greater the temperature the more decreasing the adsorption energy (e). this indicates that the adsorption process occurring at the varied temperature undergoes an exothermic condition which means the process releases energy. this state suggests for chemistry states (chemical adsorption) (vimoses et al, 2009). the determination of the adsorption capacity (b) is determined by the equation 2 which expresses the adsorbent's ability to adsorption the congo red presented in table 2. the table shows when the temperature increases, the larger the adsorption capacity. the subsequent thermodynamic parameters of enthalpy (δh) and entropy (δs) of the congo red dye adsorption process by the hydrotalcite and hydrotalcite intercalated are presented in table 3. the table shows the entropy (δs) of congo red adsorption by hydrotalcite intercalated indicates the degree of irregularity that occurs where large entropy values indicate that the smaller the concentration the degree of irregularity or greater entropy. in addition to the enthalpy value (δh) of congo red adsorption by the hydrotalcite intercalated presented in table 3 indicates a decrease as concentration increases. study of adsorption congo red dye by hydrotalcite and hydrotalcite intercalated the congo red adsorption interaction study by hydrotalcite adsorbent and the hydrotalcite intercalated was carried out to determine the changes occurring in the adsorbent prior to the adsorption process and after the adsorption process. the change of each adsorbent is seen through characterization using ft-ir spectrophotometer. figure 5 and 6 show the ft-ir spectrum, before and after the congo red adsorption process. figure 5 shows the comparison of the double layer hydroxy spectrum prior to adsorption and double layer hydroxy after adsorbing congo red differences in each bonding vibration. figure 5 after adsorbing congo red indicates the wave number of 3000-3500 cm-1 indicated that there is a vibration peak of oh and nh whereas for fig. 10 before adsorbing a strong and widespread vibration congo red is a vibration of -oh only. the presence of congo red vibrations is amplified by a peak at 1635 cm-1 which is slightly dilated with low intensity this is due to the bend vibration of oh which coincides with the vibration of the azo structure (n = n) which is characteristic of congo red (zvezdova, 2014). when compared to figure 20 before adsorbing the congo red wave numbers at 1653 cm-1 with high enough intensity and sharpness indicates only oh bend vibration. figure 3. adsorption congo red dye varied of concentration and temperature by hydrotalcite 0 10 20 30 40 50 60 0 50 100 150 a d so rb e d ( p p m ) time (min) 0 20 40 60 80 0 20 40 60 a d so rb e d ( p p m ) adsorbent (ppm) 30 40 50 60 70 said et al. / science and technology indonesia 2(1) 2016:17-21 @2017 published under the terms of the cc by nc sa 4.0 license 20 figure 4. adsorption congo red dye varied of concentration and temperature by hydrotalcite intercalated the congo red color has a s = o vibration shown in figure 20 after adsorbing congo red at the peak of vibration with a very low intensity at 1072 cm-1 wave numbers. in addition, the aromatic c = c vibration appears at 1481 cm-1 wave numbers. the symmetric stretching vibration of the n-o nitrate of the double layer hydroxyl compound with reduced intensity of the double layer hydroxyl before the adsorption process is present at the wave number 1371 cm-1 and the vibration of the 1419 cm1 wave number indicates the buckling of c-n (kaur and rajvir, 2016). tabel 2. the adsorption capacity and adsorption energy of the congo red dye adsorption process by hydrotalcite and the hydrotalcite intercalated adsorbent oc b (mg/g) e (kj/mol) hydrotalcite 30 0.548 7.670 40 1.880 7.033 50 2.865 6.180 60 8.130 5.720 70 22.222 0.799 hydrotalcite intercalated 30 1.295 10.752 40 2.092 1.826 50 4.525 10.675 60 3.861 3.684 70 9.091 3.861 the double layer hydroxyl adsorbent inserted with the h4[αsiw12o40]•nh2o polyoxometalate compound before and after the congo red adsorption process is shown in figure 6. figure 6 shows the hydroxyl of the double layer inserted prior to the adsorption process shown by the ft-ir spectrum in fig. 6 before the congo red adsorption process shows a wider and larger peak when compared to figure 6 of the double layer hydroxy insertion after the adsorption process has a peak showing the characteristic of the congo red, there is a widened and strong peak which is a vibration of -oh and nh at wave numbers 3000-3600 cm-1. at the same wavelength region the adsorbent before the insertion process has a widened peak which is the vibration of the oh alone is shown in fig. 6. figure 6 hydroxyl layer of hammer after congo red adsorption process at wave number 2924 cm-1 there is a peak of aromatic benzene vibration from congo red, peak vibration for azo structure n = n and oh buckling is present at wave number 1635 cm-1, aromatic c = c vibration at wave number 1481cm-1, for vibration of no bend is at wave number 1373cm-1 and vibration s = o is at number wave 1072 cm-1. the presence of a characteristic peak of congo red dyestuff vibration indicates that congo rally absorbed into the adsorbent surface resulting in changes in the ft-ir spectrum before and after the adsorption process. tabel 3.the subsequent thermodynamic parameters of enthalpy (δh) and entropy (δs) of the congo red dye adsorption process by the hydrotalcite and hydrotalcite intercalated adsorben co r2 δh δs layered double hydroxide 10 0,9280 84,511 0,281 20 0,9330 76,114 0,251 30 0,8910 64,059 0,212 40 0,9100 70,810 0,227 50 0,9780 84,387 0,265 intercalated layered double hydroxide 50 0,9030 40,838 0,136 60 0,9290 38,967 0,1277 70 0,9380 39,200 0,127 80 0,9060 39,20 0,118 90 0,9780 28,242 0,091 figure 5. ft-ir spectrum of hydrotalcite and hydrotalcite intercalated figure 6. ftir spectrum of double layer hydroxide inserted polyoxometalate, which adsorp congo red (a), and double layer hydroxide insertes polyoxometalate. 0 20 40 60 80 100 0 25 50 75 100 a d so rb e d ( p p m ) adsorbent (ppm) 30 40 50 60 70 said et al. / science and technology indonesia 2(1) 2016:17-21 @2017 published under the terms of the cc by nc sa 4.0 license 21 conclusion adsorption process of congo red dye by double layer hydroxy and double layer hydroxy inserted polyoxometalate h4[αsiw12o40] •nh2o (1:1) showed adsorption rate of 13.64 and 51.38 min-1. while the adsorption thermodynamic parameters for both adsorbents showed an increase in adsorption capacity along with increasing temperature. other thermodynamic parameters such as enthalpy and entropy decrease with increasing dye concentration. the effect of ph indicates that the optimum ph for the double layer hydroxy compound is at ph 9, and the polyoxometalate-insulated double-hydroxied hydroxy is at ph 8. references asif, m., haitao, w., shuang, d., aziz, a., zhang, g., xiao, f., liu, h. (2017). metal oxide intercalated layered double hydroxide nanosphere: with enhanced electrocatalytic activity towards h2o2 for biological applications. sensor and actuators b: chemical, 239, 243-252. bhoi, k, s., 2010. adsorption characteristic of congeored dye onto pac and gac based on s/n ratio. thesis. india: national institute of techonology roulkela. duan, x., lu, j., evans, d.g. (2011). assembly chemistry of anion-intercalated layered materials. modern inorganic synthetic chemistry, chapter 17, 375-404, elsevier. frost, l, ray., musumeri, w, a., bostrom, w., jones, w., kooli, f., 1997. insersition of electrochemically reduced keggin anion into ldh. j,matter chem. 7(9) : 1937-1939. jia, y., fang, y., zhang, y., miras, h.n., song, f-y. 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(2017). adsorption of congo red using mg/al hydrotalcite. science & technology indonesia, 1(1), 25-28. vimoses, vipasiri., lei, shaomin., jin, bo., chow., and saint, c., 2009. kinetic study and equilibirium isotherm analysis of congo red. xie, w., reng, hong., chem, l., 2006. calcined mg/al hydrotalcite as solid based catalysis for methanolysis of soybean oil. journal of molecular catalysis. 246 : 24-32. yang, s., huang, y., and li yu., 2011. catalytic application of h4siw12o40/sio2 in synthesis of acetals and ketals. advanced materials research, 284-286: 2374-2379. zhao, s., xu, j., wei, m., and song, f, y., 2011. synergistic catalysis by polyoxometalate-intercalated layered double hydroxide:oximation of aromatic aldehyd. green chem. 13 : 384-388 zvezdova, dilyana., 2014. preparation, characterization and adsorption properties of chitosan nanoparticles for congo red as a model anionic direct dye. naccni trudove na rusendev university. 53(10) : 83-87 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 1, january 2021 research paper facile detection of oil adulteration using uv-visible spectroscopy coupled with chemometric analysis nina gusti1, dinda oktarina1, rina elvia1, euis nursa’adah1, rendy w. wardhana1, agus sundaryono1, m. lutfi firdaus1* 1graduate school of science education, university of bengkulu, indonesia *corresponding author: lutfi@unib.ac.id abstract engine and machine oils, be�er known as lubricant, is a fast-moving part within the motorcycle and automobile industries. due to its high demand, these oils are o�en counterfeited by irresponsible people to get more profit. the thing most o�en done to adulterate oil is by mixing it with other low-quality or used oil. here, we propose a simple analytical method to identify oil adulteration by using uv-visible spectroscopy coupled with chemometric analysis. a number of 425 genuine and adulterated oils were used as samples. a�er appropriate dilution using n-hexane, the samples were analyzed by uv-visible spectrophotometer followed by principle component analysis (pca) and principle component regression (pcr) as part of the chemometric analysis. the results show that prediction samples were accurately classified into their corresponding groups with pca scores of 49% and 27% for principal component 1 and 2, respectively. pls model achieved a good prediction to detect lubricant oil adulteration, with r-square of predicted and reference samples were 0.9257 and 0.9204, respectively. the proposed method shows a promising alternative to the conventional chemical method using a more sophisticated instruments such as gc-ms and hplc for oil or other organic compound identification. keywords lubricant oil, adulteration, uv-visible spectroscopy, chemometrics, multivariate analysis received: 14 october 2020, accepted: 18 december 2020 https://doi.org/10.26554/sti.2021.6.1.14-18 1. introduction lubricant, generally, contains 90% base oil and less than 10% additives. base oil may derive from petroleum fractions, mineral oils, vegetable oils or synthetic liquids such as hydrogenated polyole�ns, esters, silicones, �uorocarbons and many others (iłowska et al. (2018); liu et al. (2019a)). synthetic oil is a manmade lubricant that consists of chemically modi�ed materials such as petroleum components (liu et al., 2019b). oil is used as lubricant due to it reduces friction; the lubricant is more slippery than the components it is applied to. a reduction in friction generate easier movement, less wear on components, and reduced energy needs of the system (díaz tovar et al., 2018). currently, renewable lubricants with tailored molecular architecture are also introduced to the market (liu et al., 2019a). high population growth followed by the increase of purchasing power has resulted in more vehicles being produced and used worldwide. engine (lubricant or machine) oil is one of the fast-moving items in a vehicle whose production is increasing due to the high demand. this results in increasing oil price, accompanied by the oil adulteration that is becoming more widespread. therefore, it is necessary to develop an analytical method to detect oil adulteration. up to today, the qualitative and quantitative analysis of oil have been conducted using one or combination of hplc, gc-ms and ft-ir (escandar et al. (2006); mobaraki and hemmateenejad (2011); wiberg (2006)). chemometrics technique were often embedded to the analysis of organic compounds for a more comprehensive and present additional insight on the analysis (hanrahan (2008); miller and miller (2018)). in this paper, we report the development of uv-vis spectrometry coupled with chemometrics technique to discriminate lubricant-oil adulteration that provide a robust and low-cost alternative to the conventional chemical method. 2. experimental section 2.1 materials dilution of oil samples were conducted by using n-hexane as a solvent. this n-hexane and other chemicals were purchased from merck (darmstadt, germany). various lubricant oils were purchased from local market in bengkulu city, indonesia. cheaper and used oils that is often used to adulterate lubricant were obtained from traditional motorbike service and workshop (figure 1 ). a genesys 20 uv-visible spectrophotometer from thermo fisher scienti�c (massachusetts, usa) was used to obtain the https://doi.org/10.26554/sti.2021.6.1.14-18 nina gusti et. al. science and technology indonesia, 6 (2021) 14-18 figure 1. the photograph of genuine oil x (a), genuine oil y (b), and adulterated oil (c) spectra. quartz and glass cuvettes, beaker glass, erlenmeyer were used for samples preparation and analysis. the chemometrics analysis was done by using the unscrambler x software from camo analytics (oslo, norway). 2.2 methods as much as 5 genuine oils from di�erent companies were purchased from the authorized motorcycle workshop. in addition, we purchased various low-quality oils and used oils from traditional motorcycle workshop as samples of mixture and adulterated oils. before analyzed, oils were �ltered and diluted with n-hexane in order to get appropriate absorbance when analyzed by uv-visible spectrophotometer. dilution of oil with n-hexane was conducted from 10% (9:1) to 90% (1:9) dilution factors. the prepared samples in cuvettes were scanned from 420 to 920 nm using uv-visible spectrophotometer. a total number of 425 samples were analyzed in this research, including 5 genuine lubricant oil samples. the csv �les from spectrophotometer were converted and processed with ms excel software (microsoft, usa) and further analyzed in unscramble x software using two models, i.e. principal components analysis (pca) and partial least squares (pls), as chemometrics analysis (nunes (2014); tan et al. (2015); wold et al. (2001)). 3. results and discussion 3.1 uv-visible spectroscopy figure 2 shows the typical spectra of uv-visible for genuine and adulterated oils at wavelength from 220 to 920 nm. the mixture of oil, including those of adulterated ones, shows distinct absorbance between 350 to 390 nm that we used as the basis to di�erentiate various lubricant and its mixtures using this simple least square technique. in general, a good separation between each sample were observed from 300 to 420 nm wavelength. therefore, a good linear correlation between oil impurity and absorbance were noticed, as shown in figure 2. however, at low wavelength from 220 to 300 nm, the noise of spectra was high and thus it is impossible to di�erentiate between genuine and adulterated ones using a simple and traditional linear regression. at high wavelength from 520 to 920 nm, the spectra were uniform almost for all samples. in order to obtain a more comprehensive results of adulterated oil identi�cation, a more complex computation of the whole uv-visible spectra using chemometric technique is necessary. therefore, we use chemometric as multivariate analysis to elucidate the uv-visible spectra. figure 2. typical uv-visible spectra of nonand adulterated-oil at wavelength from 220 to 920 nm. the dotted-line box shows the best spectra separation that can be used to draw a simple linear regression figure 3. simple linear regression (slr) of oil impurity versus absorbance at 380 nm wavelength a simple linear regression of oil impurity versus absorbance at wavelength of 380 nm is shown in figure 3. since the color of diluted oil is pale yellow, it shows a good linearity in ultra violet range with r-square = 0.9891 with linear equation of y = 1.1694x + 0.0437. genuine oil shows a lower absorbance due to a clearer liquid compared to the adulterated ones. absorbance ranges from 0.2 to 1.1 that shows a wide dynamic range and in turn it will provides a high sensitivity. 3.2 chemometrics analysis two models of chemometrics, i.e. principal components analysis (pca) and partial least squares (pls), were chosen as multivariate techniques to analyze the principal component in oil samples. the pca technique is well known to predict adulteration of samples with appropriate precision and sensitivity (herrero-latorre et al., 2019). figure 4 shows the pca plot derived from uv-visible spectra from 220 to 920 nm wavelength of oil using a projection onto the �rst two principal components. a good separation of genuine and adulterated oils was achieved with percentage of the �rst principal component (pc-1) and the second principal component (pc-2) were 49% and 27%, respectively. these results show that both pc-1 and pc-2 components represent 76% of the total variability, and successfully capturing the data structures. according to sugianti et al. (2016), if the number of variants of pc 1 and pc 2 are greater than 70%, © 2021 the authors. page 15 of 18 nina gusti et. al. science and technology indonesia, 6 (2021) 14-18 figure 4. principal components analycsis (pca) derived from uv-visible spectra of oil using a projection onto the �rst two principal components figure 5. partial least squares (pls) derived from oil uv-visible spectra then the score plot shows a good two-dimensional visualization. therefore, prediction samples were accurately classi�ed into their corresponding groups of pc-1 and pc-2. various genuine oils were identi�ed as a cluster between -5 to -10 (pc-1) and -2 to +1 (pc-2), while those of adulterated oils were located between +5 to +10 (pc-1) and +2 to +7 (pc-2). the second model of chemometrics technique used in this research was partial least squares (pls), as shown in figure 5. the uv-visible spectra from 220 to 920 nm wavelength of 425 samples were applied using a full cross-validation classi�cation model. the r-square of predicted and reference samples were 0.9257 and 0.9204, respectively. the calibration model with r-square greater than 0.91 is treated to be an excellent prediction (suhandy and yulia, 2017). these high value of r-square, i.e., close to 1.0, con�rm that the pls model is appropriate to discriminate the genuine lubricant oil and adulterated ones. furthermore, the value of mean squared error (rmsecv) was low enough for both predicted and reference samples, i.e. 0.0052 and 0.0053, respectively. these low values show that pls model is not over �tting which is a good result for the purpose of this research (sirisomboon and posom, 2019). table 1 shows the application of chemometric techniques to analyze various samples that mixed with impurities. most of the samples are organic compounds and thus hplc, gc-ms, ft-ir and uv-vis spectrometry were employed as an initial instrumentation part. detected samples include pharmaceuticals, food, coffee, wine, and oil. the advantage of uv-vis spectrometry among other methods is its simple operation procedure. furthermore, colored samples such as oil can be easily detected using visible spectrometry. further works will include the digital image colorimetry coupled with chemometric techniques and smartphone applications (firdaus et al. (2019); herrero-latorre et al. (2019)). the most common chemometrics techniques used for organic analysis were pcr and pls, including those of the present study. the results of present study show that both techniques, i.e., pcr and pls, can be used as qualitative and quantitative analytical method to identify the adulteration of lubricant oils. 4. conclusions we have successfully discriminated genuine and adulterated oil samples using a simple and rapid method of uv-vis spectroscopy coupled with chemometrics technique. both model of pca and pls achieved good prediction to detect lubricant oil adulteration, with r-square of predicted and reference samples were 0.9257 and 0.9204, respectively. the results suggest that the proposed method is a promising alternative with a low-cost and less chemicals for assessment of lubricant oil adulteration. 5. acknowledgement this work was funded by indonesian kemenristek-brin, under grant number 8/e1/kpt/2020 and 036/sp2h/lt/drpm/2020 for master thesis (m.sc) research project. references barbosa, m. f., d. s. do nascimento, m. grünhut, h. v. dantas, b. s. f. band, m. c. u. de araújo, and m. insausti (2017). fast determination of biodiesel content in commercial diesel/biodiesel blends by using digital images and multivariate calibration. analytical sciences, 33(11); 1285–1289 bhaskar, r., r. bhaskar, m. k. sagar, v. saini, and k. bhat (2012). simultaneous determination of verapamil hydrochloride and gliclazide in synthetic binary mixture and combined tablet preparation by chemometric-assisted spectroscopy. journal of analytical sciences, methods and instrumentation, 02(03); 161–166 chen, y., s.-b. zhu, m.-y. xie, s.-p. nie, w. liu, c. li, x.-f. gong, and y.-x. wang (2008). quality control and original discrimination of ganoderma lucidum based on high-performance liquid chromatographic �ngerprints and combined chemometrics methods. analytica chimica acta, 623(2); 146–156 costa, g. b., d. d. s. fernandes, v. e. almeida, t. s. p. araújo, j. p. melo, p. h. g. d. diniz, and g. véras (2015). digital image-based classi�cation of biodiesel. talanta, 139; 50–55 díaz tovar, j. s., s. valbuena-duarte, and f. racedo-niebles (2018). study of non-linear optical properties in automobile lubricating oil via z-scan technique. revista facultad de ingeniería universidad de antioquia, (86); 27–31 didham, m., v. k. truong, j. chapman, and d. cozzolino (2020). sensing the addition of vegetable oils to olive oil: the ability of uv–vis and mir spectroscopy coupled with chemometric analysis. food analytical methods, 13(3); 601–607 dinç, e. and ö. üstündağ (2003). spectophotometric quantitative resolution of hydrochlorothiazide and spironolactone in © 2021 the authors. page 16 of 18 nina gusti et. al. science and technology indonesia, 6 (2021) 14-18 table 1. application of chemometric techniques for various samples analysis analytical chemometric sample reference method model hplc pca pharmaceutical (wiberg, 2006) pls pharmaceutical (chen et al., 2008) gc-ms pca pharmaceutical (escandar et al., 2006) (pan et al., 2011) (gröger and zimmermann, 2011) pls metabolomics ft-ir pls carbonyl (mobaraki and hemmateenejad, 2011) pca food (foca et al., 2011) uv-vis pcr pharmaceutical (hadad et al., 2008) spectrometry pcr wine (martelo-vidal and vázquez, 2014) pls pharmaceutical (bhaskar et al., 2012) pca, pls co�ee (souto et al., 2015) mlr pharmaceutical (dinç and üstündağ, 2003) pca, pls olive oil (didham et al., 2020) pca, pls lubricants oil present study digital image pls biodiesel (costa et al., 2015) colorimetry (barbosa et al., 2017) lda vegetable oil (milanez et al., 2017) tablets by chemometric analysis methods. il farmaco, 58(11); 1151–1161 escandar, g. m., p. c. damiani, h. c. goicoechea, and a. c. olivieri (2006). a review of multivariate calibration methods applied to biomedical analysis. microchemical journal, 82(1); 29–42 firdaus, m. l., a. aprian, n. meileza, m. hitsmi, r. elvia, l. rahmidar, and r. khaydarov (2019). smartphone coupled with a paper-based colorimetric device for sensitive and portable mercury ion sensing. chemosensors, 7(2); 25 foca, g., f. masino, a. antonelli, and a. ulrici (2011). prediction of compositional and sensory characteristics using rgb digital images and multivariate calibration techniques. analytica chimica acta, 706(2); 238–245 gröger, t. and r. zimmermann (2011). application of parallel computing to speed up chemometrics for gc× gc–tofms based metabolic �ngerprinting. talanta, 83(4); 1289–1294 hadad, g. m., a. el-gindy, and w. m. mahmoud (2008). hplc and chemometrics-assisted uv-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule. spectrochimica acta part a: molecular and biomolecular spectroscopy, 70(3); 655–663 hanrahan, g. 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(2006). quantitative impurity pro�ling by principal component analysis of high-performance liquid chromatography–diode array detection data. journal of chromatography a, 1108(1); 50–67 wold, s., m. sjöström, and l. eriksson (2001). pls-regression: a basic tool of chemometrics. chemometrics and intelligent laboratory systems, 58(2); 109–130 © 2021 the authors. page 18 of 18 introduction experimental section materials methods results and discussion uv-visible spectroscopy chemometrics analysis conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 4, october 2018 research paper adsorption of cobalt (ii) on layered double hydroxides (mg/al and ca/al) in aqueous medium : kinetic and thermodynamic aspect neza rahayu palapa1, tarmizi taher2, muhammad said1, risfidian mohadi1, aldes lesbani1* 1magister of chemistry, faculty of mathematic and natural sciences, sriwijaya university, jl.. padang selasa bukit besar palembang 30139 22department of enviromental science, graduate school, sriwijaya university, jl. padang selasa no. 524 ilir barat 1, palembang-south sumatra, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstract layered double hydroxides mg/al and ca/al has been synthesized by co-precipitation method with molar ratio m2+:m3+ (3:1) at ph 10. the synthesized materials were characterized by xrd and ftir. the materials were used as adsorbent for the removal cobalt (ii) in aqueous solution. the adsorption experiments were studied through some variables adsorption such as variation of contact time, variation of temperature and variation of initial concentration. kinetic parameters was obtained from variation of contact time. data was analyzed by pseudo-first-order and pseudo-second-order kinetics models in linear analyses. the kinetic studies showed that the adsorption process more fitted by pseudo-second-order than pseudo-first-order based on coefficient correlation. isotherm parameters was calculated using langmuir and freundlich isotherm models. the adsorption process was spontaneous and endothermic. keywords layered double hydroxides, adsorption, cobalt (ii) received: 14 september 2018, accepted: 19 october 2018 https://doi.org/10.26554/sti.2018.3.4.189-194 1. introduction layered material are classi�ed into two groups, cationic clays and anionic clays. cationic clays are found in nature and anionic clays are easily synthesized. layered double hydroxides (ldh) belong to the anionic clay minerals was consist of sheets of the hydroxides of two metals di�erent valence. the metals hydroxides layeres are positively charged, so neutrality charged requires must be anion intercalated into interlayer. usually, hydroxil ions was present as anion and this anion can be readily exchanged by others such as carbonate ions (rosenberg and armstrong, 2016). ldhs has general formula [m2+(1-x)m3+x(oh)2](an-)x/nh2o, where m2+ and m3+ are di-valent and tri-valent cations such as mg2+, fe2+, co2+, cu2+, ni2+, ca2+ and al3+, cr3+, ga3+, mn3+ or fe3+ (hongo et al., 2017). this layer materials have high �exibility cation exchange and easily synthesized in laboratory (zhao et al., 2011). layered double hydroxide has many potential aplications for layered double hydroxides including catalysis, adsorption and �ame retardant composite (clark et al., 2017). there have been many studies were focusing on the aplication of layered double hydroxides as adsorbent zhao et al. (2011); el-sayed et al. (2016); said and palapa (2017). layered double hydroxides was used to adsorpted heavy metals zhao et al. (2011) and stable at ph >5 up to 12 (costantino et al., 2013). as known, the presence of heavy metals in the environment can be harmful to variety of living species. therefor, the removal of heavy metals from waste water is important to public health. the industrial waste water usually containing cobalt (ii) is common. the adsorption of heavy metals in solution can be removed using several technique such as adsorption, precipitation, coagulation, chemical precipitation, ion-exchange, ozonation and membran �ltration (shou et al., 2015). the adsorption is recognized as an easy, economic and e�ective to removed heavy metals from the waste water (el-sayed et al., 2016; taher et al., 2018). in this research, synthesis and characterization of layered double hydroxides was conducted using frourier transform infra red (ft-ir) and x-ray difractometer (xrd). the adsorption process of layered double hydroxides is intended to determine the kinetic and thermodynamic parameters by measuring residual concentration and adsorbed using atomic adsorption spectrophotometer. 2. experimental section the chemicals used are analytical grade such as magnesium nitrate, alumunium nitrate, calsium nitrate, sodium carbonhttps://doi.org/10.26554/sti.2018.3.4.189-194 palapa et. al. science and technology indonesia, 3 (2018) 189-194 ate, sodium hydroxide and cobalt nitrate. water was supplied from integrated research lab graduated school, sriwijaya university. analysis instrument were used ft-ir shimadzu prestige-21, xrd shimadzu lab x-type 6000 and atomic adsorption spectrophotometer novaa 350 analytic jena. 2.1 synthesis of layered double hydroxides synthesis of layered double hydroxides mg/al was conducted according to (palapa and said, 2016). synthesis of layered double hydroxides ca/al was conducting using 100 ml of a solution containing 0.3 mol ca(no3)2 ·h2o and 0.1 mol al(no3) ·9h2o under vigorous stirring, while was added dropwise 2 mol/l of naoh at ph 11 then stirring until 24 h to form white solid material and dried at room temperature to obtain ca/al layered double hydroxides (rojas, 2014). 2.2 adsorption experiment kinetic parameter 0.05 g layered double hydroxides mg/al and ca/al each added into 50 ml of cobalt (ii) shaker with variations in contact time varied. the solution of the adsorbed cobalt (ii) substance was separated by �ltration and then measured its concentration by using atomic adsorption spectrophotometer. thermodynamic parameter thermodynamic adsorption of cobalt (ii) using adsorbent 0.05 g layered double hydroxides mg/al and ca/al each added into 50 ml cobalt (ii) by variying the with each adsorption temperature is 30 ºc, 35 ºc, 40 ºc, 45 ºc, 50 ºc. the solution of the adsorbed cobalt (ii) substance was separated by �ltration and then measured its concentration by using atomic adsorption spectrophotometer. 3. results and discussion 3.1 adsorbent characterization characterization of layered double hydroxide was carried out using the ft-ir. the ft-ir of the layered double hydroxides mg/al and ca/al is shown in figure 1. the vibration at wavenumber 3300-3800 cm−1 is assigned as streching of o-h and the bending of o-h at 1635 cm−1. the bending of nitrate is appeared at wavenumber 1381-1388 cm−1. these vibration was unique vibration for layered double hydroxides. the vibrations of al-o, ca-o and mg-o were appreated at 563 cm−1 , 424 cm−1 and 416 cm−1 respectively. the xrd patterns of mg/al and ca/al material were shown in figure 2. the unique structure of layered double hydroxides was identi�ed at di�raction angle. this difraction 100 and 600 indicated that presence of layered materials and the anion on the interlayered. xrd pattern of ca/al in figure2b was shown semiliar to that reported by hongo et al. (2017) when synthesis of material was carried out at temperature was 27 ºc (room temperature), the peak intensity of calcite was stong, its because layered double hydroxides contained calcite. figure 1. ft-ir spectrum of layered double hydroxides mg/al (a) and layered double hydroxides ca/al (b) figure 2. xrd patterns of layered double hydroxides mg/al (a) and layered double hydroxides ca/al (b) 3.2 kinetic adsorption of cobalt (ii) on mg/al and ca/al layered double hydorxides in order to establish the equilibrium time for maximum adsorption, the adsorption of of cobalt (ii) was investigated as the function of contact time. kinetic adsorption of cobalt (ii) on layered double hydroxides mg/al and ca/al was studied by investigated adsorption time as shown in figure 3. figure 3 shows that mg/al and c/al layered double hydroxide increased slowly after an hour with percentage adsorp 84% and 78%, respectively. the fast removal adsorption can happen because the adsorbent surfaces have large number of site to adsorb co(ii) solution, then the rate of adsorbent was decreased when the surface site full of adsorbate accumulated. to identify the rate kinetics of the adsorption process, two kinetics models, namely the pseudo-�rst-order (pfo) and seudo-second-order (pso) have been employed to �t the experimental data. the © 2018 the authors. page 190 of 194 palapa et. al. science and technology indonesia, 3 (2018) 189-194 figure 3. e�ect of contact time on the adsorption of cobalt (ii) onto mg/al and ca/al ldhs pseudo-�rst-order kinetics model desribes the adsorption of liquid/solid system based on solid capacity. the model can be written as: dqt dt = k1(qe− qt) (1) log(qe− qt)= logqe− k1 2.303 t (2) where qe and qt are the capacity of metal ions adsorbed (mg g−1) at equilibrium and time t (h), respectively, and k1 is the pfo rate constant(h−1). thus the value of qe and k1 can be determined experimentally by plotting log(qe-qt) versus t and extracting information from the least squares analysis of slope and intersept into eq (1). the seudo-second-order adsorption kinetic is expressed as following formulation: dqt dt = k2(qe− qt)2 (3) t qt = 1 k2qe2 + 1 qe t (4) where k2 (g mg−1 h−1) is the pso rate constant for the adsorption process. thus values of k2 and qe can be calculated from intercept and the slope of the linear relationship eq (4) between t/qt and t. the calculated values of k1 , k2 , and coe�cient correlation (r2) obtain in table 1. the result indicated that linear of pfo model did not give reasonable values with regard to the experimentals of co(ii). however, the (r2) values are low for linear pfo comparing with (r2) values obtain from pso. these result suggest that the second order mechanism is predominant, table 1. kinetics models for the adsorption of co (ii) kinetics models parameters adsorbent mg/al ca/al pseudo-�rst-order qe exp (mg/g) 17.0769 16.9949 qe calc (mg/g) 18.7013 13.2092 k1 (min-1) 0.0714 0.0359 r2 0.9367 0.9722 pseudo-seconds-order qe exp (mg/g) 17.0769 16.9949 qe calc (mg/g) 18.7798 18.3765 k2 (min-1) 0.0053 0.0185 r2 0.992 0.995 in which the adsorption mechanism depends on the adsorbate and adsorbent. the result was shown in table 1. table 1 was calculated value of k1 and k2, qe exp, qe calc together with (r2). the value of correlation coe�cient mgal and ca/al (r2) = 0.99 for pseudo-second-order model was better �tted than pseudo-�rstorde for adsorption co(ii) by mgal and ca/al layered double hydroxides, respectively. the data obtained in table 1 also showed that the layered double hydroxides mg/al has a more reactive than ca/al because layered double hydroxides mg/al has the adsorption rate (0.0053 (min−1)) lower than layered double hydroxides ca/al (min−1). 3.3 thermodynamic adsorption of cobalt (ii) on mg/al and ca/al layered double hydroxides the thermodinamics parameters was studied by varied of concentration and temperature. thermodynamics were used two models isotherm for this data langmuir and freundlich ishotherm models. the langmuir assumed that adsorbate was occupied onto monolayer. its used equation as follows: ce qe = 1 klqmax + ce qmax (5) where qe is the equilibrium adsorption, ce is equilibrium concentration, qmax is the maximum adsorption and kl is the equilibrium adsorption constant. then, the essential features of langmuir isotherm namely rl (equilibrium parameters). value rl has indicated the models of isotherm. if irreversible, the rl calculated zero (rl = 0), liniear when rl = 1, and favorable when 0> rl>1 (kumar et al., 2012). the freundlich isotherm model identi�ed the heterogenous adsorbent surface. the equation is following: logqe = logkf +nlogce (6) where kf is adsorption capacity when equilibrium. thermodynamic adsorption of cobalt (ii) on layered double hydroxides mg/al and ca/al was studied by variying concentration and temperature. adsorption data by layered double hydroxides mg/al and ca/al in figure 4 and figure 5. therefore, both the isotherm models are shown in table 2. based on correlation © 2018 the authors. page 191 of 194 palapa et. al. science and technology indonesia, 3 (2018) 189-194 table 2. langmuir and freundlich isotherm models correlation parameter t= 303 k t= 308 k t= 313 k t= 318 k langmuir mg/al ca/al mg/al ca/al mg/al ca/al mg/al ca/al qmax 18.288 17.453 22.726 18.463 25.773 21.098 36.855 21.318 kl 0.0626 0.071 0.085 0.077 0.080 0.070 0.0557 0.073 rl 0.000680.0054 0.000710.0056 0.000540.0043 0.000670.0054 0.000480.0035 0.000590.0047 0.000330.0027 0.000580.00046 r2 0.996 0.994 0.995 0.994 0.995 0.992 0.994 0.991 freundlich mg/al ca/al mg/al ca/al mg/al ca/al mg/al ca/al kf 1.391 1.933 2.025 2.040 1.969 1.847 2.1433 2.149 n 1.505 1.802 1.476 1.856 1.366 1.537 1.299 1.609 r2 0.894 0.706 0.741 0.718 0.798 0.677 0.848 0.829 figure 4. adsorption of cobalt (ii) varied concentration and temperature by layered double hydroxides mg/al coe�cient of the data, langmuir isotherm models more �tted than freundlich isotherm models. its indicated the adsorption was accour in monolayer adsorption coverage onto ldhs particles and also the homogeneous distribution of active sites adsorbent (lin et al., 2014). the isotherm was found to be linear studied by good correlation coe�cient (r2 =0.99). the data in table 2 was showed the monolayer adsorption capacity cobalt (ii) have a higher value at 318 k using mg/al ldhs (36.855 mg/g). thermodynamic investigation plays an indispensable part in the prediction of adsorption mechanisms (i.e., physical or chemical). thermodynamic parameters (∆g°, ∆h°, and ∆s°) can be calculated according to the thermodynamic laws through the following equations: ∆g =−rt lnkc (7) then, the relationship between thermodynamics parameter written by: ∆g =∆h −t∆s (8) figure 5. adsorption of cobalt (ii) varied concentration and temperature by layered double hydroxides ca/al the van’t ho� equation was obtain by equation (7) and (8): lnkc = ∆h r · 1 t + ∆s r (9) the gibbs energy was calculated by equation (7), then the enthalpy (∆h) and the entropy (∆s) were obtained from a plot of lnkc versus 1/t, the plot were determined slope and intercept (equation (9)). in this study the kc derived from the langmuir constant (kl) was employed for calculation of the thermodynamic parameters. the thermodynamic parameters for adsorbing cobalt (ii) onto the mg/al and ca/al ldhs respectively were showed in table 3. table 3 were showed the negative values of ∆g were investigated the adsorption was spontaneously. meanwhile, the positive ∆h re�ects the endothermic nature of the adsorption process and the equilibrium constant (table 3) at a higher temperature. additionally, the positive ∆s values suggest that an increase in irregularity on the surface with several structural changes both adsorbate and adsorbent. in addition, when the adsorbate is adsorbed on the surface sites, the adsorbate replaces several molecules of water which is its can increasing the entropy. © 2018 the authors. page 192 of 194 palapa et. al. science and technology indonesia, 3 (2018) 189-194 table 3. values of thermodynamic parameters for the adsorption of cobalt (ii) by mg/al and ca/al ldhs t (k) concentration (mg/l) mg/al ca/al ∆g ∆s ∆h ∆g ∆s ∆h (kj/mol) (j/mol.k) (kj/mol) (kj/mol) (j/mol.k) (kj/mol) 303 10 -4.712 85.806 21.286 -1.005 69.614 21.666 308 -6.429 -2.384 313 -8.145 -3.736 318 -8.784 -3.943 303 20 -2.762 111.236 37.480 -0.199 84.261 33.365 308 -5.049 -1.104 313 -7.336 -2.008 318 -8.309 -3.489 303 30 -1.381 114.342 31.883 -0.245 96.094 42.864 308 -4.823 -1.175 313 -8.265 -2.105 318 -8.905 -4.997 303 50 -0.231 138.846 44.383 -0.378 110.654 58.418 308 -0.463 -0.984 313 -3.248 -1.591 318 -4.567 -3.856 303 80 -0.672 172.093 50.761 -0.378 122.035 78.148 308 -2.114 -0.984 313 -3.082 -1.591 318 -3.787 -2.345 4. conclusions adsorption process of cobalt (ii) on layered double hydroxides mg/al and ca/al showed the adsorption rate 0.0053 min−1 and 0.0185 min−1, respectively. layered double hydroxides 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(2014). copper, lead and cadmium removal by ca al layered double hydroxides. applied clay science, 87; 254– 259 rosenberg, s. p. and l. armstrong (2016). layered double hydroxides in the bayer process: past, present and future. in essential readings in light metals. springer international publishing, pages 235–239 said, m. and n. r. palapa (2017). adsorption of congo red using mg/al hydrotalcite. science and technology indonesia, 1(2); 17–21 shou, j., c. jiang, f. wang, m. qiu, and q. xu (2015). fab© 2018 the authors. page 193 of 194 palapa et. al. science and technology indonesia, 3 (2018) 189-194 rication of fe3o4/mgal-layered double hydroxides magnetic comosites for the e�ective decontamination of co(ii) from synthetic wastewater. journal of molecular liquids, 207; 216–223 taher, t., d. rohendi, r. mohadi, and a. lesbani (2018). thermal and acid activation (taa) of bentonite as adsorbent for removal of methylene blue: a kinetics and thermodynamic study. chiang mai journal of science., 45; 1770–1781 zhao, d., g. sheng, j. hu, c. chen, and x. wang (2011). the adsorption of pb (ii) on mg2al layered double hydroxide. chemical engineering journal, 171(1); 167–174 © 2018 the authors. page 194 of 194 introduction experimental section synthesis of layered double hydroxides adsorption experiment results and discussion adsorbent characterization kinetic adsorption of cobalt (ii) on mg/al and ca/al layered double hydorxides thermodynamic adsorption of cobalt (ii) on mg/al and ca/al layered double hydroxides conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 3, july 2020 subject index 1. absolute bias 2. autocorrelation 3. bayesian quantile regression method 4. biodiesel 5. censored data 6. censored quantile regression 7. chitosan 8. classification system 9. confidence interval 10. fuzzy 11. heterogeneous catalyst 12. improved näıve bayes 13. ketepeng cina 14. nanoparticles 15. p. acne 16. quantile regression 17. quantile regression method 18. sodium-alginate 19. standard error 20. submicroparticles 21. transesterification 1 article http://sciencetechindonesia.com article history received: 12 february 2017 received in revised form: 15 may 2017 accepted: 25 may 2017 doi: 10.26554/sti.2017.2.3.76-79 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 67-69 preparation of calcium oxide from cattle bones as catalyst for conversion of waste cooking oil to biodiesel sabat okta ceria sitompul1, risfidian mohadi1* 1 department of chemistry, faculty of mathematics and natural sciences, university of sriwijaya, indralaya, oi 30622 indonesia *corresponding author : email: risfidian.mohadi@unsri.ac.id abstract preparation of calcium oxide from cattle bones by thermal decomposition for 3 hours using various temperature at 400°, 500°, 800°, 900°, 1000°, and 1100°c. calcium oxide was characterized using x-ray diffractometer. the results of xrd pattern showed of diffraction similar to cao standard from jcpds at 2θ: 32.2°; 37.3°; 53.8°; 64.1° and 67.3°. the cao from heating cattle bones at 1000°c resulting of 2θ: 32.3°; 53.8° and 64.1°. then, the metal oxide was characterized by ft-ir which showed the existence of cao at wave number 362.2 cm-1 from cao vibration. the cao from cattle bones applied as catalyst on biodiesel synthesis from waste cooking oil and resulting viscosity value of biodiesel 5.93 cst, density 0.876 g/cm3, acid value 0.561 mg/koh and iod number value 16.92 g/100 g, respectively all in the range of sni standard. keyword: cattle bones, calcium oxide, catalyst, biodiesel, waste cooking oil introduction the use of petroleum for various activities has led to the depletion of petroleum stocks. therefore another alternative must be sought as a substitute for petroleum. one of the alternative fuels that have been developed over the years is biodiesel. biodiesel is one of the attractive alternative fuels that can be produced from renewable sources. the standard process for biodiesel processing is by transesterification process. the synthesis of biodiesel by transesterification reaction will not take place without a catalyst. one type of catalyst used to synthesize biodiesel from triglycerides with alcohol, the base catalyst (verma et.al, 2016). alkaline catalysts often used as naoh, koh, and calcium hydroxide (ca(oh) 2 ) is a homogeneous alkaline catalyst system. however, the use of such catalysts has a disadvantage, i.e., the separation of the catalyst from the product is quite complicated. other basic catalysts commonly used are metal oxide catalysts such as cao, mgo (lee et.al., 2014). the base catalyst of this metal oxide class has a heterogeneous system. the use of heterogeneous catalysts offers many advantages because this catalyst is separated from the product and can be reused. but the price of these metal oxide catalysts is expensive. therefore, the research effort to find the source of the cheap heterogeneous catalyst obtained from nature and also friendly to the environment. there are several sources of calcium such as eggshells, mollusks, and bones. bone consists of organic and inorganic materials. approximately 20% of the bones are water, and the rest consists of inorganic materials such as calcium phosphate (65-70%), protein and collagen matrix (30-35%). inorganic materials of natural sources contain the main components of calcium phosphate and calcium carbonate, with little magnesium, fluoride, and sodium, phosphorus, manganese, tin and copper (prasuna et.al, 2004). sources of raw materials for synthesizing biodiesel include vegetable oils such as jatropha seeds, rubber, palm oil. another source that can be used into biodiesel is waste cooking oil. the waste cooking oil is the rest of the household provided abundant forms the basis of an attractive and increase economic value into biodiesel. ho et.al. (2014) have synthesized biodiesel with raw materials from waste cooking oil using heterogeneous base catalyst which cao derived from snail shells (achatina fulica) calcinated at a temperature of 700 oc. the research shows the ratio of methanol and transesterification of waste cooking oil (40: 100) at a temperature of 65 ° c to form methyl ester is an average of 35 ml. in this study synthesized cao catalyst from cattle bones was applied to transesterification reaction of biodiesel manufacture from wasteland oil to be utilized as a catalyst for an industrial process other than biodiesel (minaria and mohadi, 2017. experimental section chemicals and instrumentation the instrumentations are used in this research glasses flask, reflux apparatus, viscometer, water bath, pycnometer, shimadzu lab x-6000 x-ray diffractometer, shimadzu ftir prestige-21, and sem jeol jed-2300. the materials used are cattle bone, phosphoric acid, methanol, phenolphthalein, potassium hydroxide, oxalic acid, hanus solution (iodine-bromide reagent), 15% potassium iodide, starch, chloroform, ethanol, sodium thiosulfate. methods base catalyst preparation from cattle bone cattle bone is taken from several locations in a traditional market in palembang city. the cattle bones that have been obtained are washed and dried in an oven at a temperature of 100 °c to remove water. cattle bones are crushed and sifted to a 100 mesh size. preparation of waste cooking oil sample waste cooking oil was taken from food stalls in the indralaya district. waste cooking oil was filtered using whatman no.40 filter paper to clean it. the filtered oil is store in a plastic container. fatty acids determination in waste cooking oil by titration cooking oil of 5 grams is weighed, then added with 96% ethanol of 10 ml, refrigerated to boiling, then shaken until completely dissolved. the resulting sample is titrated with pp indicator using a koh titrant to produce a pink color. fatty acid formula: = standardization of koh a total of 102 mg of oxalic acid were included in a 250 ml erlenmeyer, then 25 ml aquadest were added. the mixture is added with pp indicator and titrated with 0.1 n koh which will be standardized until the solution is pink in color. iteration was performed three times. sitompul et al. 2017/science & technology indonesia 2 (3) 2017:76-79 © 2017 published under the term of the cc by nc sa 4.0 license 77 determination of iodine number in waste cooking oil by hanus method the waste cooking oil is weighed as much as 0.5 g and then loaded into erlenmeyer. 10 ml of chloroform solution and 25 ml of hanus solution (iodine-bromide reagent) are added, shaken until all oil is well blended and let stand in a dark room for 30 minutes. 10 ml of 15% ki solution added. titration is done with a solution of na 2 s 2 o 3 0.1 n and the indicators used are starch 1%, titration until a clear solution. na 2 s 2 o 3 0,1n use was recorded. iod numbers where : a = number of ml thio solution for the titration of the sample b = number of ml thio solution for blank titration preparation and characterization of base catalyst cattle bones cattle bones that pass a 100 mesh sieve as much as 100 grams of calcined with a furnace in oxygen atmosphere conditions at various temperature variations. the temperature variations used were 400, 500, 800, 900, 1000, and 1100 ° c for 3 hours. after the cold solids are then it stored in the desiccator for 24 hours. characterization is performed by using x-ray diffraction. the result of the obtained characterization compared with jcpds data which is standard for xrd diffraction pattern data. study of transesterification of cooking oil with preparation catalyst into biodiesel the transesterification reaction was performed using a 500 ml threeneck flask equipped with a pumpkin flap. a total of 100 ml of waste cooking oil was added 40 ml of anhydrous methanol followed by the addition of a basic catalyst of cattle bone as much as 0.2 g. the reaction was heated at 65 ° c. for 3 hours. the reaction is stopped by using ice water. the reaction product was left overnight to obtain multiple phases, followed by separation by addition of 1 ml h 3 po 4 for the neutralization process. determination of viscosity value of biodiesel product the sample is inserted into the viscometer, then covered with a rubber ball, then the lid is opened, and the sample is allowed to flow. the sample flow time is recorded from the first line to the second line in seconds. if the flow time is less than 200 seconds, then the determination is repeated using a viscometer that has a smaller factor. the same treatment is done for biodiesel after distillation. viscosity formula: kv = f x t where: kv = kinematic viscosity f = the viscometer factor used t = flow time of example determination of density value of biodiesel product density measurements carried out in the water bath at a temperature of 40 °c empty pycnometer first weighed, then pycnometer filled with a biodiesel product that is obtained, then weigh it. repetition is done three times. the same test performed for aquadest as a comparison. results and discussion identification of cao metallic oxide of preparation from cattle bone using xrd calcium oxide analysis resulting from the calcination process using xrd. data xrd diffractogram generates patterns derived calcium compounds include cao, ca(oh) 2 and caco 3 as the main compound. pattern diffractogram produced consistent with the patterns of calcium oxide released by the joint committe on powder diffraction standard (jcpds) as presented in table 1. characteristics of calcium compounds at any temperature variation is analyzed through the observation of 2θ according to the standards. in accordance to the jcpds diffractogram in the figure. 2, the selection of cao to be used as a base catalyst in the synthesis of biodiesel from cooking oil through a transesterification reaction process is the cattle bone heated at a temperature of 1000ºc. this can be seen from the resulting cao peaks approaching the standard jcpds diffractogram for cao. the 2θ value of cattle bones 1000ºc heating is 32.3°; 53.8° and 64.1° with the intensity values sequentially by 117.13 and 15. a value of 2θ from cattle bones 1100ºc heating is 32.2°; 53.2° and 64.1° with successive intensity values of 165.33 and 17. identification of calcium oxide that results from the preparation of cattle bones decomposition with analysis using ft-ir spectroscopy in this study, cattle bone heating at 1000 ° c was analyzed by ftir. the measured ft-ir spectra are presented in figures 3. in figure 3 shows that the presence of functional groups in the region 400-4000 cm -1 wave number. the wave number range can be divided into two main areas namely in the range of 400-1000 cm -1 wave numbers as an area for identification of inorganic compounds and local wave number range 1000-4000 cm -1 as a base uptake organic compounds to facilitate the observation. in the wave number around 3400 cm-1 contained in the cattle bone as shown in figure 3 which shows the -oh group. this indicates the presence of crystal water formed at cao where the wavelength indicates the shifting vibration of the -oh group. a number range calcium carbonate and hydroxide legible at 400-1000 cm -1 (tang et.al, 2013). figure 1. difactogram of cao table 1. data 2θ (jcpds) for the compounds of cao, ca(oh) 2, caco 3 compounds 2θ cao 34.2º 37.3º 53.8º 64.1º 67.3º caco 3 29.4º 39.4º 43.2º 47.4º 48.5º ca(oh) 2 28.6º 34.1º 47.1º 50.8º figure 2. diffractogram of cattle bones heating results at various temperatures sitompul et al. 2017/science & technology indonesia 2 (3) 2017:76-79 © 2017 published under the term of the cc by nc sa 4.0 license 78 calcium oxide is the expected target solids in this study was observed in the range of 250-400 cm -1 wave number. ft-ir spectra of cattle bones heating at a temperature of 1000 ° c and ft-ir spectra of standard cao is presented in figure 3 shows the peaks that appear to vibration almost identical between the standard cattle bones and cao. cao absorption bands in cattle bone decomposition at temperatures of 1000 °c seen in the area around 362.2 cm-1 that indicates vibration of the metal oxides cao preparation results. oco bond stretching of carbonate appears at wave number 1465.9 cm-1. early identification of cattle bone using sem-edx analysis the result of sem-edx analysis for the bone of cattle bone can be seen in figure. 4 and figure. 5. the surface morphology of cattle bone before heating with 1000x magnification is seen not homogeneous due to different composition between cattle bone. the composition of cattle bone can be seen from edx data in figure 8 which is carbon 64.14%, oxygen equal to 24.82%, sodium equal to 0.25%, magnesium equal to 0.24%, posfor equal 3.64% and calcium 6.92%. the edx data of cattle bone before heating process at various temperature variation obtained low calcium element content. although calcium is not the main component in cattle bones a but can be used as a candidate to obtain cao. sem-edx analysis on cattle bones heated at 1000 °c cattle bones that have been through the process of heating at various temperatures and have done xrd analysis that produces the best cao from cattle bones at a temperature of 1000 °c subsequently analyzed by sem-edx. the results of sem-edx analysis for cattle bones at 1000 °c can be seen in figure 6 and 7. in figures 6, there is a significant difference with cattle bones before heating process. cattle bones composition, from heating at 1000 °c can be seen from the data in figure 7 namely edx carbon by 11.21%, 44.21% oxygen, sodium at 2.01%, amounting to 1.14% magnesium, phosphorus amounted to 14.37 % and calcium by 24.83%. the high carbon content initially decreased, but the calcium content grew by 6.91% to 24.83%. from the sem-edx data in figures 6 and 7 it is clear that the structure of the heating cattle bone has a higher homogeneity than before heating. the application of cao from cattle bone as a catalyst in the synthesis of biodiesel from cooking oil the transesterification process is carried out for 3 hours through a reflux process to achieve the value or the maximum amount of methyl esters formed. the use of pure h 3 po 4 was added as a solvent reactant strongly acidic alkaline neutralizing acidic conditions in the transesterification process. methyl ester which is biodiesel obtained through transesterification reaction with heated cao catalyst is 20 ml, with calculation yield obtained is 14.28%. the value of fatty acid number of biodiesel product the result of the determination of fatty acid number on biodiesel production from waste cooking oil by titration method got the average value of repetition 3 times equal to 0.561 mg/koh using cao catalyst from cattle bone. according to the data of sni 04-7182-2006, the maximum value of fatty acid number found in biodiesel is 0.8 mg/koh. the data shows that the biodiesel product has a value that is in accordance with the standard. high acid numbers can cause sediment in the fuel system and corrosion of the media. the higher the acid number the lower the quality of biodiesel (pinyaphong, 2011). iod value of biodiesel product the result of the determination of iodine number of biodiesel product obtained average value from repetition 3 times is 16.92 g/100 g for cattle bone catalyst. the result of the analysis shows that iodine number in biodiesel from synthesis according to standard biodiesel value determined by sni (lesbani et.al, 2015). biodiesel with a high content of iodine number exceeds constant biodiesel quality standard maximum of 115 g/100 g will lead to a tendency to polymerization and formation of deposits on injectors noozle and piston rings at the start of combustion. density value of biodiesel product density provides information on how the fuel will work in diesel engines. according to the standard astm d-1298 (1999), a specific gravity of diesel fuel specifications in the range of 0.85 to 0.89 g / cm 3. the test was performed on methyl ester with measurement according to astm standard with laboratory scale. the use of high temperature to the transesterification reaction will increase the saponification reaction. the presence of impurities such as glycerol from the saponification reaction so that the impurities formed form the mass of the biodiesel species to become larger. high mass types indicate some impurities contained in biodiesel (pinyaphong, 2011). the results of the analysis of methyl ester density were measured with three repetitions of the average values obtained are 0.8844g/cm 3 for cattle bones catalyst. these results indicate that the resulting product meets the astm standard of density used. figure 3. ft-ir spectra of cao from cattle bones heating at 1000 °c and cao standards. figure 5. edx analysis results from cattle bones figure 4. results of sem photograph of cattle bones sitompul et al. 2017/science & technology indonesia 2 (3) 2017:76-79 © 2017 published under the term of the cc by nc sa 4.0 license 79 viscosity value of biodiesel product viscosity is defined as fluid resistance to the flow rate of a mm-sized capillary. the test results obtained after three times the viscosity repetition obtained an average of 5.93 cst and 6.03 cst. the recommended restriction is astm d-445 with a viscosity of diesel fuel specification that is in range 2.3 – 6.0 cst. if the price of viscosity is too high it will be big friction losses in the pipeline, the pump work will be heavy, the filtration is difficult and the possibility of the dirt come too big, and difficult to disregard the fuel. conversely, if the viscosity of biodiesel it will result a thin lubrication. conclusion cattle bone heating at a temperature of 1000 °c was produced cao as a catalyst. the xrd data of cattle bones 1000 °c has a value of 2θ: 32.3°; 53.8°, and 64.1°. the ft-ir data showed that cao appears at the wave number 362 cm-1. as well as from sem-edx data the surface morphology of cattle bones after heating at 1000 °c was seen to be more homogeneous compared to not heated. biodiesel product from waste cooking oils catalyzed by cao from cattle bones have a viscosity of 5.93 cst, the density of 0.876 g/cm 3, the acid number of 0.561 mg/koh and an iodine number of 16.92 gi 2 /100 g in accordance to the biodiesel standards. references ho. k-c., chen. c-l., hsiao. p-x., wu. m-s., huang. c-c., chang. j-s. (2014). biodiesel production from waste cooking oil by two-step catalytic conversion.” in the 6th international conference on applied energy – icae2014, energy procedia, 61, 1302 – 1305. lee. h.v., juan. j.c., abdullah. n.f.b., rabiah nizah mf. r., taufiq-yap. y.h. (2014). heterogeneous base catalysts for edible palm and non-edible jatropha-based biodiesel production. chemistry central journal, 8, 30. lesbani. a., susi. y., verawaty. m., mohadi. r. (2015). calcium oxide decomposed from chickens and goats bones as catalysts for conversting discarded cooking oil to be biodiesel. aceh international journal of science and technology, 4, 7-13. minaria., mohadi. r. (2016). preparation and characterization of calcium oxide from crab shells (portunus pelagicus) and its application in biodiesel synthesis of waste cooking oil, palm and coconut oil. science and technology indonesia, 1,1-7. prasuna. c.p.l., narasimhulu. k.v., gopal. n.o., rao. j.l., rao. t.v.r.k. (2004). the microstructures of biomineralized surfaces: a spectroscopic study on the exoskeletons of fresh water (apple) snail, pila globosa. spectrochimica acta part a, 60, 2305-2314. pinyaphong. p., sriburi. p., phutrakul, s. (2011). biodiesel fuel production by methanolysis of fish oil derived from the discarded parts of fish catalyzed by carica papaya lipase. world academy of science, engineering and technology, 76, 466-472. tang. y., xu. j., zhang. j., lu. y. (2013). biodiesel production from vegetable oil by using modified cao as solid basic catalysts. journal of cleaner production, 42, 198-203. verma. p., sharma. m.p., dwivedi. g. (2016). impact of alcohol on biodiesel production and properties. renewable and sustainable energy reviews, 56, 319-333. figure 6. sem photograph of cattle bones heated at 1000 °c figure 7. edx analysis of cattle bone heating results 1000 °c title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 research paper comparison of two priors in bayesian estimation for parameter of weibull distribution ferra yanuar1*, hazmira yozza1, ratna vrima rescha1 1department of mathematics, faculty of mathematics and natural science, andalas university, kampus limau manis, 25163, padang-indonesia *corresponding author: ferrayanuar@sci.unand.ac.id abstract this present study purposes to conduct bayesian inference to estimate scale parameters, denoted by θ, with known location parameter or β, of weibull distribution. there are two types of prior distributions used in this study, conjugate prior and non informative prior. as conjugate prior is inverse gamma, and as non-informative prior is jeffreys’ prior. this research also aims to study several theoretical properties of posterior distribution based on prior used implement it to generated data and make comparison between both bayes estimator as well. the method used to evaluate as the best estimator is based on the smallest mean square error (mse) value. this study proveds that bayes estimator using conjugate prior produces better estimated parameter value estimate non-informative prior since it produces smaller mse value, for condition θ > 1 based on analytic and simulation study. meanwhile for θ < 1 both priors could not yield acceptable estimated parameter value. keywords bayesian inference, weibull distribution, prior conjugate, non-informative prior, mean square error received: 20 june 2019, accepted: 18 july 2019 https://doi.org/10.26554/sti.2019.4.3.82-87 1. introduction weibull models are used to describe various types of observed failures of components and phenomena. the weibull distribution is widely used in life data analysis, reliability engineering and elsewhere due to its versatility and also its relative simplicity. much of the attractiveness of the weibull distribution is due to the wide variety of shapes which can assume by altering its parameters. the two-parameter weibull distribution has one shape and one scale parameter. the random variable x follows weibull distribution with the shape and scale parameters respectively denoted by β,θ >0 has probability density function of the form (aslam et al., 2014) f(x|θ,β) = β θ x β−1 i exp [ − x β i θ ] ,x ≥ 0,θ,β > 0 in this study, we concern the estimation of the scale parameter of the weibull distribution, with known shape parameter. many studies has been done in estimating such parameter using the maximum likelihood estimator (mle) and/or bayes method, such as study conducted by ieren and oguntunde (2018), aslam et al. (2014) or abdulabaas et al. (2013). all studies obtained that bayes method yielded better estimated value than mle. in using bayes method, most of researchers used the noninformative prior as the prior distribution, those are uniform prior or jeffreys’ prior. meanwhile many studies suggested to use the conjugate prior in order to obtain better estimated values (thamrin et al., 2018), (corrales and cepeda-cuervo, 2019). no work has been done in comparing between conjugate prior and non-informative prior yet. thus, this present study aims to explore the comparison between both priors distribution in bayes estimation method analitically and using simulation study (muharisa et al., 2018). the theoritical properties of both bayes estimator are also studied. in section 2 we presents the literature review related to bayes methods including invers gamma distribution as conjugate prior and jeffreys’ method as non-informative prior. results from theoritical and simulation study and also discussions are presented in section 3. meanwhile conclusions from this study are provided in section 4. 2. basic concepts in bayesian method suppose that x1,x2,. . . ,xn are random sample from the distribution with pdf f(x;θ)where θ is the parameter of the distribution. estimation of parameters θ will be based on random samples x1,x2,. . . ,xn. the bayes method is one parameter estimation method that can be used for https://doi.org/10.26554/sti.2019.4.3.82-87 yanuar et. al. science and technology indonesia, 4 (2019) 82-87 this purpose. the bayes method combines the likelihood function and the prior distribution of the parameters to be estimated, so that the posterior distribution is obtained which will be the basis of the parameter estimation (thamrin et al., 2018). the best estimator is the estimator which produces the smallest mse value. the mse of µ is calculated based on the following formulae mse(µ) = v ar(µ)+[b(µ)]2 (corrales and cepeda-cuervo, 2019). 2.1 likelihood function in weibull distribution if x1,x2, ..., are random samples from weibull distribution, written as wei(θ,β) with unknown β, so that its likelihood function is: f(x|θ) = n∏ i=1 f(xi; θ) = n∏ i=1 β θ x β−1 i exp [ − (xβi θ )] = (β θ )n( n∏ i=1 x β−1 i ) exp [ − (∑n i=1 x β i θ )] (1) 2.2 invers gamma distribution as conjugate prior if a random variable y has invers gamma distribution with scale parameter ω > 0 and shape parameter τ > 0 written as y ∼ ig(τ,ω), are respectively (aminzadeh and deng, 2018) f(y; τ; ω) = ωτ γ(τ) y−(τ+1)e− ω y ,y > 0 and 0 elsewhere expectation and variance of y ∼ ig(τ,ω) are formulated as follow; e(y ) = ω τ − 1 ,τ > 2 v ar(y ) = ω2 (τ − 1)2(τ − 2) ,τ > 2 in this study, it is assumed that x ∼ wei(θ,β), with knownβ, and parameter θ will be estimated using bayes method. it is assumed that parameter θ is a random variable and it has invers gamma distribution with parameter τ = 1 and ω = 1, written θ ∼ ig(1, 1) as conjugate prior distribution. probability density function forθ ∼ ig(1, 1) is: f(θ) = 11 γ(1) θ−(1+1) exp ( − 1 θ ) = θ−2 exp ( − 1 θ ) ,θ > 0 (2) then the posterior distribution for θ will be determined using equations (1) and (2) and modifying both of them with the formula as follows: (maswadah et al., 2013) f(θ|x) = f(θ|x)f(θ)∫ f(θ|x)f(θ)dθ = f(x,θ) f(x) = βn ∏n i=1 x β−1 i θ −(n+2)exp [ − 1 θ ( σni x β−1 i + 1 )] βn ∏n i=1 x β−1 i ( σni=1x β i + 1 )−(n+1) γ(n + 1) = ( σni=1x β i + 1 )(n+1) γ(n + 1) θ −(n+2)exp [ −1 θ ( σni x β−1 i +1 )] (3) based on eq. (3) it’s identified that θ|x using conjugate prior has invers gamma distribution with parameters n + 1 and ∑n i=1 x β i +1 denoted by θig|x ∼ ig ( n+1, ∑n i=1 x β i +1 ) . 2.3 jefferys’ prior as non-informatif prior jeffreys’ prior is the most widely used noninformative prior in bayesian analysis. this method is also attractive because it is proper under mild conditions and requires no elicitation of hyperparameters whatsoever. jeffreys’ rule is derived from likelihood function then take the prior distribution to be the determinant of the square root of the fisher information matrix (corrales and cepeda-cuervo, 2019), denoted by f(θ) ∝ √ i(θ. fisher’s information for the parameter θ, is defined as: i(θ) = −ne [ d2 dθ2 ln f(x|θ) ] the natural logarithm of the likelihood function from data that has weibull distribution is formulated as ln(f(x|θ)) = ln ((β θ )n n∏ i=1 x β−1 i exp [ − (∑n i=1 x β i θ )]) = n[ln β − ln θ] + (β − 1) n∑ i=1 ln x1 ∑n i=1 x β i θ therefore fisher’s information for the parameter θ that has weibull distribution is given by i(θ) = −ne [ n θ2 − 2 ∑ x β i θ3 ] = (n θ )2 thus, jeffreys’ prior is defined as f(θ) ∝ √ ( n θ )2 ∝ n θ (4) © 2019 the authors. page 83 of 87 yanuar et. al. science and technology indonesia, 4 (2019) 82-87 then posterior distribution for θ is constructed as following (f(x|θ) = f(x|θ)f(θ)∫ f(x|θ)f(θ)dθ = f(x,θ) f(x) = nβn ∏n i=1 x β−1 i θ −(n+1) exp [ − (∑n i=1 x β i θ )] nβn ∏ n i=1 x β−1 i ( ∑ n i=1 x β i )n γ(n) = ( ∑n i=1 x β i ) 2 γ(n) θ−(n+1) exp [ − (∑n i=1 x β i θ )] (5) eq. (5) informed us that posterior distribution for θ|x using jeffrey’s prior has invers gamma distribution with parameters n and ∑n i=i x β i denoted by θj|x ∼ ig(n, ∑n i=1 x β i ). 3. results and discussion in this section we will present the results of several theoretical properties of bayes inference for scale parameter from weibull distribution using prior conjugate and noninformative prior. both bayes estimators will be compared using the best estimator criteria, that is the smallest value of mean square error (mse). 3.1 analytical study in this section, it will be explained theoretically the estimation process of scale parameters θ of the weibull distribution with known shape parameter β using the bayes method. in estimating parameter, it uses two types of prior distributions, namely prior conjugate, used inverse gamma distribution and noninformative prior, that is jeffrey’s method. 3.1.1 bayes inference with invers gamma distribution as conjugate prior it has been proved that θig|x ∼ ig(n + 1, ∑n i=1 x β i + 1). thus the posterior mean for θigis given by θ̂ig = e(θig) = ∑n i=1 x β i + 1 (n + 1) − 1 = ∑n i=1 x β i + 1 n ,n > 0 (6) this posterior mean is also the estimator for θig of weibull distribution with known shape parameter. the posterior variance for θig is expressed as (s′ig) = v ar(θig) = ( ∑n i=1 x β i + 1) 2 n2(n− 1) ,n > 1 (7) the (1 −α)100% bayesian credible interval for θ is approximately θ̂bayes−zα 2 (s′bayes) ≤ θ ≤ θ̂bayes+zα2 (s ′ bayes). thus (1−α)100% bayesian credible interval for θig is given by ∑n i=1 x β i + 1 n −zα 2 (√ ( ∑n i=1 x β i + 1) 2 n2(n− 1) ) ≤ θig ≤ ∑n i=1 x β i + 1 n + zα 2 (√ ( ∑n i=1 x β i + 1) 2 n2(n− 1) ) (8) then, the formula for mse for θig is determined by v ar(θ̂ig) and bias(θ̂ig). formula for v ar(θ̂ig) and bias(θ̂ig) respectively are v ar(θ̂ig) = 1 n2 n∑ i=1 v ar(x β i + 1) = 1 n2 (nθ2) = θ2 n bias(θ̂ig) = e(θ̂ig) −θ = nθ + 1 n −θ = 1 n therefore formulae for mse is given by mse(θ̂ig) = v ar(θ̂ig) + [bias(θ̂ig)] 2 = θ2 n + [ 1 n ]2 = nθ2 + 1 n2 (9) 3.1.2 bayes inference with jeffreys’ prior as noninformative prior based on eq. 5 is known that θj|x ∼ ig(n, ∑n i=1 x β i ) estimator of scale parameter θ̂j is provided by the posterior mean that is given by θ̂j = e(θj) = ∑n i=1 x β i n− 1 ,n > 1 (10) and the posterior variance is expressed as (s′j)2 = v ar(θj) = (∑n i=1 x β i ) (n− 1)2(n− 2) ,n > 2 (11) the (1 − α)100% bayesian credible interval for θj is given by ∑n i=1 x β i n− 1 −zα 2 (√ ( ∑n i=1 x β i ) 2 (n− 1)2(n− 2) ) ≤ θj ≤ ∑n i=1 x β i n− 1 + zα 2 (√ ( ∑n i=1 x β i ) 2 (n− 1)2(n− 2) ) (12) while formulae for mse is approximately v ar(θ̂j) = v ar (∑n i=1 x β i n−1 ) = 1 (n−1)2 ∑n i=1 v ar(x β i ) = 1 (n−1)2 (nθ 2) = © 2019 the authors. page 84 of 87 yanuar et. al. science and technology indonesia, 4 (2019) 82-87 table 1. bayes inference for scale parameter, true value for θ=2 criteria sample size conjugate prior non-informative prior (invers gamma) (jeffreys’ prior) estimated mean n = 25 1.68624 1.71483 n = 100 1.80989 1.81807 n = 150 1.82652 1.83207 estimated variance n = 25 0.11847 0.12785 n = 100 0.03308 0.03372 n = 150 0.02239 0.02267 mse n = 25 0.11533 0.13273 n = 100 0.03285 0.03406 n = 150 0.02228 0.02282 width of n = 25 1.34927 1.40166 bayesian credible interval n = 100 0.71305 0.71991 n = 150 0.58656 0.59033 nθ2 (n−1)2 and bias(θ̂j) = e(θ̂j) − θ = nθ n−1 − θ = θ n−1 . thus mse is expressed as mse(θ̂j) = var(θ̂j) + [bias(θ̂j)] 2 = nθ2 (n− 1)2 + [ θ n− 1 ]2 = (n + 1)θ2 (n− 1)2 (13) 3.1.3 comparison of both mses based on two formulaes for mse, (θ̂ig) and mse(θ̂j) obtained above, it will be determined which one is better estimator. it has been obtained that mse(θ̂j) = (n+1)θ2 (n−1)2 . in the case θ > 1, implies θ2 > 1, so mse(θ̂j) = nθ2 + θ2 (n− 1)2 > nθ2 + 1 (n− 1)2 > nθ2 + θ2 n2 = mse(θ̂ig) for condition θ > 1, it is proven that mse(θ̂j) > mse(θ̂ig) it means the value of the mse with prior conjugate (inverse gamma) is smaller than mse with noninformative priors (jeffreys’ prior). this means that the bayes estimator with conjugate priors is better estimator than noninformative priors. 3.2 simulation study this research then conducted a simulation study to implement the result of analytical study above. the simulation study also aims to examine how similar the estimates of the parameters of the models are, compared with the true values of the parameters. in this simulation study, n = 25, 100 and 150 data were generated from weibull distribution, wei(2, 1). based on n = 25, it is calculated that ∑25 i=1 x β i = 41.1560. here, it is assumed that β = 1, the value of ,θ will be estimated using the bayes method. in this study, we consider two conditions for θ, these are θ > 1 and θ < 1. 3.2.1 bayes inference for parameter θ > 1 with conjugate prior it has been obtained that the posterior distribution for θig is invers gamma distribution, written as ig(n + 1, ∑n i=1 x β i + 1). so that the posterior distribution for θig based on generated data is ig(26 , 42.15606). posterior mean for θig is e(θig) = ∑n i=1 x β i +1 n = 1.686242, posterior variance for θig is v ar(θig) = ( ∑n i=1 x β i )2 n2(n−1) = 0.1184755. furthermore, the mse value based on generated data is mse(θ̂ig) = nθ2+1 n2 = 0.1153365. by taking α = 5%, the 95% bayesian credible interval for θig is approximately (1.011605 ; 2.360879). 3.2.2 bayes inference for parameter θ > 1 with non informative prior it is obtained that posterior distribution for θj is invers gamma distribution, θj ∼ ig(n, ∑n i=1 x β i ). based on generated data, it is obtained θj ∼ ig(25, 41.15606). the posterior mean is e(θj) = ∑n i=1 x β i n−1 = 1.714836 and posterior variance is v ar(θ̂j) = ( ∑n i=1 x β i )2 (n−1)2(n−2) = 0.1278549. meanwhile mse value is mse(θ̂j) = (n+1)θ2 (n−1)2 = 0.1327382. the 95% bayesian credible interval for θj is approximately (1.014003 ; 2.415669) the same process then implemented to n = 100 and 150 generated from weibull distribution as well. complete results of calculation for all three groups of data are presented in table 1. from the table 1 above, it can be seen that the bayes estimator with prior invers gamma produces the estimated value is closer to the true value for θ = 2 compared to © 2019 the authors. page 85 of 87 yanuar et. al. science and technology indonesia, 4 (2019) 82-87 table 2. simulation study for estimate scale parameter θ <1 for n = 100 criteria true value for θ invers gamma prior jeffreys’ prior estimated mean 0.3 11.1743 11.27708 0.5 1.12287 1.12411 0.7 0.9266 0.92586 0.9 0.83726 0.83561 estimated variance 0.3 1.26126 1.29767 0.5 0.01273 0.01289 0.7 0.00867 0.00874 0.9 0.00708 0.00712 mse 0.3 1.24875 1.31052 0.5 0.0127 0.01302 0.7 0.00868 0.00883 0.9 0.00711 0.00719 width of bayesian confidence interval 0.3 4.40239 4.46549 0.5 0.44238 0.44512 0.7 0.36505 0.36662 0.9 0.32985 0.33088 jeffrey’s prior for all three groups data. in general it can be seen that both estimators are consistent estimator because more data, the estimated value increasingly approaching the true value. this present study also proved that the value of variance, the mse value of inverse gamma prior results in smaller value than jeffrey’s prior for all three selected sample sizes. invers gamma prior also results narrower 95% bayesian confidence interval for all three sample sizes compared to jeffreys’ prior. the same estimation process is also carried out for several true values for θ > 1 and linear results are obtained. thus it can be concluded that for θ > 1, the prior conjugate is better estimator than prior non-informative for case of parameter of weibull distribution. 3.2.3 bayes inference for parameter θ < 1 in the same ways as in the previous section, simulations are carried out for several values for θ < 1. to save the space, simulation study was done for n = 100 with the true values for θ are 0.3, 0.5, 0.7 and 0.9. complete results of the study are provided in table 2. based on table 2 above, it can be seen that the bayes estimator with the two selected priors produces estimated mean that does not approach the corresponding true values. the estimated value is further away from the true value of θ which is set for the value of θ which is close to 0. the estimated value here are not acceptable. therefore, this simulation study proved that the scale parameter of the weibull distribution for θ < 1 cannot be used. based on table 2 above, it can be seen that the bayes estimator with the two selected priors produces estimated mean that does not approach the corresponding true values. the estimated value is further away from the true value of θ which is set for the value of θ which is close to θ. the estimated value here are not acceptable. therefore, this simulation study proved that the scale parameter of the weibull distribution for θ < 1 cannot be used. 4. conclusions this study aims to compare the results of estimating scale parameters of the weibull distribution by using prior conjugates and non-informative priors on the posterior distribution. comparison is done analytically and with simulation studies. theoretically it is proven that for the value of θ > 1, the mse value of the prior conjugate will yield a smaller estimation value than non-informative priors, while the value for θ < 1 does not produce a consistent predictive value. while the results of simulation studies proved that the value of θ < 1 will produce a value that is far from the true value so that the estimated value is not acceptable. whereas for the value of θ > 1, it is concluded that the estimated value approaches the true value by increasing the sample size. invers gamma prior produced better estimate mean compared jeffreys’ prior. this conjugate prior also resulted smaller estimated variance, smaller mse and narrower bayesian credible interval than jeffreys’ prior. thus it can be concluded that inverse gamma prior (prior conjugate) gives the better estimator than jeffreys’ prior. references 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jeffreys’ prior as noninformative prior comparison of both mses simulation study bayes inference for parameter >1 with conjugate prior bayes inference for parameter >1 with non informative prior bayes inference for parameter <1 conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper prediction of plastic-type for sorting system using fisher discriminant analysis irsyadi yani1, yulia resti2*, firmansyah burlian1, ansyori3 1department of mechanical engineering, faculty of engineering, sriwijaya university, palembang, 30662, indonesia2department of mathematics, faculty of mathematics and natural science, sriwijaya university, palembang, 30662, indonesia3department of electrical engineering, faculty of engineering, sriwijaya university, palembang, 30662, indonesia *corresponding author: yulia_resti@mipa.unsri.ac.id abstractrecycling is a more environmentally friendly method of managing and reducing plastic waste that can significantly reduce landdegradation, pollution, and greenhouse gas emissions. according to its composition, an essential first step in the recycling process issorting out plastic waste. however, inadequate sorting of plastic types can result in cross-contamination and increasing industrialoperating costs. a low-cost automated plastic sorting system can be developed by using digital image data in the red, green, andblue (rgb) color space as the dataset and predicting the type using learning datasets. the purpose of this paper is to demonstratehow to use fisher discriminant analysis (fda) to predict the plastic type from a digital image of the rgb model and then evaluatethe performance using cross-validation. this work has four main steps: collecting plastic digital image data, forming statistical tests,predicting plastic types, and evaluating prediction performance. fda is quite effective for predicting the type of plastic. performancemeasures the accuracy of 87.11 %, the recall-micro of 91.67 %, the recall-micro of 80.97 %, the specificity-micro of 90.33 %, and thespecificity-macro of 90.38 %, respectively. the micro is determined by the number of decisions made for each object. in comparison,the macro is calculated based on the average decision made by each class. keywordsfisher discriminant analysis, plastic-type, prediction received: 11 july 2021, accepted: 4 october 2021 https://doi.org/10.26554/sti.2021.6.4.313-318 1. introduction although plastic is the most widely used inorganic material globally, particularly in countries experiencing rapid economic growth (srigul et al., 2016), plastic can be harmful to the environment due to its hundreds-year decomposition time (shuai et al., 2020). recycling is a viable option for managing and reducing plastic waste instead of landlls and incineration (chow et al., 2016). this step can signicantly reduce land degradation, pollution, and greenhouse gas emissions while also saving up to 95 % of the energy used in the plastic manufacturing process (siddique et al., 2008). sorting plastic waste according to its material composition is the initial step in the recycling process. this stage is critical because the improper classication of plastic types can result in cross-contamination, which increases industrial operating costs (pivnenko et al., 2016). in addition, this process frequently encounters diculties when attempting to dierentiate between dierent types of plastic (ruj et al., 2015). the plastic types polyethylene terephthalate (pet/pete), high-density polyethylene (hdpe), and polypropylene are widely used in the community and have the potential to become waste (pp). due to the ineectiveness and ineciency of the manual method, automatic plastic sorting is a viable solution to this problem. a low-cost automatic plastic sorting system can be developed by utilizing machine learning and a digital image with the rgb color model as a dataset. machine learningderived predicted plastic-type values have a purpose in the sorting process. the articial neural network backpropagation (annb) method also is implemented to predict plastic-type based on digital images (khona’ah et al., 2015; yani et al., 2020). the annb algorithm is a widely used and popular prediction/classication algorithm. however, the minimum accuracy of the classication method is 85 % (arono, 1985). additionally, the performance of the method is solely based on its accuracy. therefore, numerous metrics must be used to evaluate the eectiveness of methods (gorunescu, 2011). one of the prediction methods in machine learning is fisher discriminant analysis. this method is a powerful tool for developing a statistical prediction algorithm (raudys and young, 2004). it has proven very successful in a variety of tasks, including recognizing, assessment of risk, identication, diagnosis, or classifying (vranckx et al., 2021; chumachenko https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.313-318&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.313-318 yani et. al. science and technology indonesia, 6 (2021) 313-318 et al., 2021; bari and fattah, 2020; wang et al., 2018). this method has several models, such as lineardiscriminant analysis (lda), quadratic discriminant analysis (qda), and fisher discriminant analysis (fda). the rst two models require a gaussian multivariate assumption. only the lda and fda assume that the covariance matrix is homogeneous. when the covariance matrix is not homogeneous, the more appropriate model is qda. lda is more appropriate than qda for small sample sizes in learning data and vice versa for enormous sample sizes (james et al., 2013). the lda can also be more appropriate than qdawhen the data dimension is small (wahl and kronmal, 1977). this article proposes using fda to predict the three plastic types used in sorting systems, with ve metrics for method performance: accuracy, the micro and macro proportion of plastic types correctly predicted (recall-micro and recall-macro), and the micro and macro proportion of plastic types correctly predicted (specicity-micro and specicity-macro) (dinesh and dash, 2016; sokolova and lapalme, 2009). 2. experimental section 2.1 materials the statistics summary of image data collected related to the ve normalized predictor variables is noted in table 1. table 1. summary statistic of variable statistic predictor variable red green blue entropy variance x1 x2 x3 x4 x5 minimum 0.33 0.35 0.33 0.00 0 1st quartile 0.61 0.63 0.67 0.01 0.01 median 0.7 0.75 0.78 0.02 0.02 mean 0.76 0.79 0.8 0.01 0.05 3rd quartile 0.98 0.99 0.98 0.02 0.12 maximum 1 1 1 0.03 0.13 2.2 methods figure 1 presents the main stages of this research. each stage has a minimal one step. the rst need to get images of plastic is to build the acquisition system. this system has two key components: a web camera that takes digital images and a computer that processes the images into the rgb format. there are 450 dierent plastic data collected by capturing the images in three dierent random poses. plastic waste comes from three types; pet, hdpe, and pp. the obtained images are processed into rgb color format, where each color component has a value of 8 bits so that each color component has a scale of 28 = 256 or a pixel value range of 0 to 255. the resolution of the image stored in the database is 560 × 420 pixels. the image is cropped to 34 × 34 pixels with cropping coordinates [280 180 33 33]. figure 2 presents the three types of the cropped plastic waste digital image. figure 1. research methodology figure 2. digital image of plastic-type the second step is to check the discriminant analysis assumptions. this work proposed the discriminant analysis s related to the plastic-types prediction method. the doornikhansen (adesoye et al., 2016), the fligner-killeen (stevens, 2012), and the pillai trace (carey, 1998) tests to check multivariate gaussian distribution, covariance matrix homogeneity, and mean vector equality assumptions related to the prediction method assumptions. the tests are written in (1)–(3), doornik − hansen = ( z( √︁ \1) + +z22 ) (1) fk = ∑k j=1 nj ( x̄zj − x̄ 2 )2 s2 (2) pt = trace ( b(b +w )−1 ) (3) forthedoonik-hansentestadesoyeetal. (2016),z( √ \1) and z2 are dened respectively as, z( √︁ \1) = ln(g/c) + √︁ (g/c)2 + 1√︁ ln(𝜔) (4) z2 = (( b 2𝜑 ) 1 3 − 1 + 1 9𝜑 ) (9𝜑) 1 2 (5) © 2021 the authors. page 314 of 318 yani et. al. science and technology indonesia, 6 (2021) 313-318 where g, c, 𝜔2, b , and𝜑 are written successively as, g = √︁ \1 √︄ (n + 1)(n + 3) 6(n − 1) (6) c = √︄ 2 (𝜔2 − 1) (7) 𝜔 2 = −1 + √︁ 2𝛽2 − 1 (8) b = (b2 − 1 − b2)2k (9) 𝜑 = (n + 5)(n + 7)((n − 2)(n2 + 27n − 70) + b1(n − 7)(n2 + 2n − 5)) 6(n − 3)(n + 1)(n2 + 15n − 4) (10) for m2 and m3 are the second and third central moments, respectively, \1 = m23 m32 (11) 𝛽2 = 3(n2 + 27n − 70)(n − 3)(n + 1) (n − 2)(n + 5)(n + 7)(n + 9) (12) k = (n + 7)(n + 7)(n3 + 37n2 + 11n − 313)(n − 3)(n + 1) 12(n − 3)(n + 1)(n2+15n−4) (13) the fligner-killeen test are dened stevens (2012) successively as, s = 1 σkj=1nj σ k j=1njsj (14) for the pillai trace test b and w are formulated carey (1998) as, b = k∑︁ j=1 nj(x̄j − x̄)(x̄j − x̄)t (15) w = k∑︁ j=1 nj k∑︁ i=1 nj(xi j − x̄)(xi j − x̄)t (16) the third step is to implement the discriminant analysis to build learning models and predict the plastic types. the stages in this step are randomly split data, learning model development, and predict the plastic types into pet, hdpe, and pp for testing data. the data were randomized into ve-folds, four folds to build a learning model, and the remaining onefold to predictive data (lantz, 2019; alpaydin, 2016). the model analysis that is implemented is one of three models: linear discriminant analysis (lda), quadratic discriminant analysis (qda), or fisher discriminant analysis (fda). the model selection is based on the results of statistical testing assumptions. lda or qda can be implemented when gaussian assumptions are fullled. lda considers that all groups have the same covariance matrix, whereas qda is calculated based on the covariance matrix of each group (hastie et al., 2009). the sample size is critical when deciding whether to use lda or qda (wahl and kronmal, 1977). generally, lda is more appropriate than qda for small sample sizes in learning data and vice versa for enormous sample sizes (james et al., 2013). however, if this assumption is not met, it is more appropriate to implement the fda. the plastic image with x = (x1, x2, x3, x4, x5)t is classied as the j -th plastic-type if the discriminant function d̂j(x) is the largest. the d̂j(x) for both models, lda and qda, respectively (james et al., 2013). 𝛿(x) = ln𝜋j + xtς−1 ` j − 1 2 ` t j σj ` j (17) 𝛿(x) = ln𝜋j− 1 2 ln|σj |− 1 2 xtς−1x+xtς1j ` j− 1 2 ` t j σj ` j (18) with covariance matrix respectively, σ and σj,∀j. in fda, x is classied as the j -th plastic-type if the linear combination,yj = vtx, is maximum where, v = s−1w ( `1 − `2) (19) sw = 2∑︁ j=1 sj (20) sj = ∑︁ xi𝜖 jthg (xi − ` j)(xi − ` j)t (21) ` j = 1 nj ∑︁ xi𝜖 jthg xi (22) the nal step is to evaluate the performance of the discriminant analysis. scalar values are used to represent classication © 2021 the authors. page 315 of 318 yani et. al. science and technology indonesia, 6 (2021) 313-318 performance in various metrics such as accuracy, recall-micro (`), recall-macro (m), specicity-micro (`), and specicitymacro (m). the tpj , fpj ,tnj , and fnj values are determined for each plastic type, j = 1, 2, 3. the micro proportion is calculated based on the number of decisions per object, while the macro proportion is calculated based on the average decision per class. the performance measurements refer to table 2 for the rst plastic type. the performance measure for other plastic types is determined similarly (dinesh and dash, 2016; sokolova and lapalme, 2009). table 2. confusion matrix for plastic-type, j = 1 actual j 1 2 3 prediction 1 true-positive false-negative false-negative (tp) (fn) (fn) 2 false-positive true-negative true-negative (fp) (tn) (tn) 3 false-positive true-negative true-negative (fp) (tn) (tn) accuracy = σ3j=1 tpj+tnj tpj+fpjfnj+tn 3 (23) recall` = σ3j=1tpj σ3j=1(tpj + fnj) (24) recallm = σ3j=1 tpj (tpj+fnj) 3 (25) speci f icity` = σ3j=1tnj σ3j=1(fpj +tnj) (26) speci f icitym = σ3j=1 tnj (fpj+tnj) 3 (27) 3. results and discussion tables 3–4 summarize the results of the assumption tests for discriminant analysis for all of the learning data. this work usedthedoornik-hansenandthefligner-killeentests toassess multivariategaussiandistributionsofexplanatoryvariablesand homogeneity of covariance matrices between types of plastic waste, respectively. table 3 demonstrates that not all plastic types in all learning data have a multivariate gaussian distribution at the 5 % signicance level. only the rst, second, and fth folds datasets, table 3. multivariate gaussian test doornik-hansen test learning data 1 2 3 4 5 type of plastic pet statistic 140.96 143.88 123.75 104.97 117.42 p-value 0 0 0 0 0 hdpe statistic 397.25 456.53 351.74 369.93 300.34 p-value 0 0 0 0 0.09 pp statistic 29.05 27.37 25.77 36.07 37.22 p-value 0 0 0 0 0 and even then, only hdpe plastic-type data have a multivariate gaussian distribution. the assumption of a multivariate gaussian distribution is required for the majority of multivariate analyses. however, it is challenging to locate data with a multivariate gaussian distribution over all real-world groups (hallin and paindaveine, 2009). table 4. homogeneity of covariance matrices test fligner-killeen test learning data 1 2 3 4 5 chi-sq 4.35 0.58 0.95 1.35 1.7 p-value 0.11 0.74 0.62 0.51 0.43 the next assumption test in discriminant analysis is the homogeneityof the covariance matrix. this independent variable test is carried out when the gaussian multivariate assumption is not met. currently, the assumption of an equal mean vector is not necessary. related to the homogeneity test as described in table 4, the result shows that all learning data have a homogenous covariance matrix with a signicance level of 5 %. fda is used to make predictions based on the ndings test of the gaussian multivariate and the covariance matrix homogeneity assumptions. table 5. performance of plastic waste classication using fda performance testing data average variancemeasurement 1 2 3 4 5 accuracy 87.41 85.19 85.93 88.89 88.15 87.11 2.37 recall miu 81.11 77.78 78.89 79.07 83.22 91.67 5.29 recallm 81.03 78.86 79.07 83.22 82.68 80.97 4.04 specicity miu 90.56 88.89 89.44 91.67 91.11 90.33 1.32 specicitym 90.74 88.87 89.53 91.49 91.26 90.38 1.30 this work has an accuracy of 87.11 %, recall-micro (`) and recall-macro (m) at 91.67 % and 80.97 % respectively, specicity-micro (`) and specicity-macro (m) at 90.33 % and 90.38 % respectively. this information shows that the fda method is quite good at predicting plastic type since, according to arono (1985), the minimum accuracy of the classication method is 85 %. other than that, the specicity that calculates the truth in all plastic-types other than the selected types against all other types has the higher standard deviation (about 2 %), and the recall calculates the correctness model of statistical learning in predicting that the plastic-type has the lowest standard deviation (about 1 %). thus, this work’s result is better © 2021 the authors. page 316 of 318 yani et. al. science and technology indonesia, 6 (2021) 313-318 than khona’ah et al. (2015), who implemented the annb algorithm to predict the plastic types with an accuracyof 86.67 %. although the dierence in prediction accuracy does not reach 1 %, this work has proposed dierent validation techniques and more performance measures than khona’ah et al. (2015) to show that the prediction results have low variance. therefore, better prediction performance for plastic types than our proposed method can be obtained by implementing classication methods that do not require the assumption of a multivariate gaussian distribution and homogeneity of the covariance matrix. these methods include k-nn, decision tree, or support vector machine. 4. conclusions plastic recycling is a more environmentally friendly method of managing and reducing plastic waste that can signicantly reduce land degradation, pollution, and greenhouse gas emissions. this stage is crucial because inaccurate sorting of plastic types can cross-contamination and increase industrial operating costs. this paper evaluates the performance of the fisher discriminant analysis model to predict the plastic type using digital images. thismodelsuccessfullypredicts theplastic-type. performance measures the accuracy of 87.11 %, the micro and macro proportion of plastic-type with correctly predicted (recall) was 91.67 % and 80.97 %, respectively. in contrast, the micro and macro proportion of the plastic-type into other types predicted correctly (specicity) was 90.33 % and 90.38 %, respectively. however, superior prediction performance for plastic types can be obtained using classication methods that do not require the assumption of a multivariate gaussian distribution and homogeneity of the covariance matrix, for the examples k-nn, decision tree, or support vector machine. 5. acknowledgement the research/publication of this article was funded by dipa of public service agency of sriwijaya university 2021. sp dipa-023.17.2.677515 /2021, on november 23, 2020. in accordance with the rector’s decree number: 0010/ un9/ sk.lp2m.pt/2021, on april 28, 2021. references adesoye, j., b. golam kibria, and f. george (2016). performances of several univariate tests of normality: an empirical study. j. biom. biostat, 7; 1–8 alpaydin, e. 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publishing, page 012015 © 2021 the authors. page 318 of 318 introduction experimental section materials methods results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 research paper physical interaction of chitosan-alginate entrapping extract of papaya leaf and formation of submicron particles dosage form budi untari1, dina permata wijaya1, mardiyanto1*, herlina1, via angraeni1, ario firana1 1department of pharmacy faculty of science, sriwijaya university (unsri) *corresponding author: mardiyantounsri@gmail.com abstract research on physical interaction of chitosan-alginate entrapping extract of papaya leaf (carica papaya l) into submicron particles formation has been performed. preparation of papaya leaf extract into submicron particle dosage form of chitosan and sodium alginate polymer using ionic gelation method aimed to increase the solubility of extract. submicron particles consisting of papaya leaf extract, chitosan, sodium alginate and cacl2 were combined using variation of stirrer speed of 500, 750, and 1000 rpm. the optimum formula obtained has a speed of 1000 rpm with the percent ee value of 71.90%. the results of submicron particles characterization such as diameter and particle size distribution (pdi) using particle size analyzer (psa) tools were 189.2 nm and 0.330. the results of xrd revealed the changes of type of crystalinity form to amorphous on submicron particles. the results of ftir revealed the physical interaction without shi�ing of wave number of carbonyl, amine, and hydroxyl group which indicated that there were no chemical interactions occurred. these data indicated that papaya extract can be formulated into submicron particles of chitosan-alginate polymer. keywords interaction, chitosan-alginate, papaya leaf, submicron-particles received: 20 june 2019, accepted: 18 july 2019 https://doi.org/10.26554/sti.2019.4.3.64-69 1. introduction solubility is one of the limitations of extract for production of the dosage form. study regarding physical interaction is focussed to solve the problem of solubility (akerholm and salmen, 2001) problem of solubility is relevant to bioavalability level of active ingredient in blood circulation of human. the classi�cation system of bioavalabilty was classi�ed by 4 types: biopharmaceutics classi�cation system (bcs) class i to iv. bcs ii is poor of solubility and good of permeation. using of hydrophylic polymer such as chitosan (berger et al., 2004) which has interaction to active ingredients can increase the solubility (kim et al., 2002). dhf is a disease caused by the dengue virus that is transmitted through the bite of the aedes aegypti mosquito (moektiwardoyo et al., 2014; natalia et al., 2013). herbal medicines has already used (lin et al., 2014; jain et al., 2008) to encourage the pain of hemorrhagic fever (dhf) (suwanbamrung et al., 2013; zunjar et al., 2016). papaya extract is also can be used as anti dhf (ahmad et al., 2011). vector control is one of the solutions to eradicate dengue diseases. one of them is by utilizing chemicals such as abate® powder, but the use of these chemical larvacides produces a lot of residues that can inhibit the growth of other non-targeted organisms, in�uence human health and in repeated administration can lead to resistance cases. an alternative strategies to reduce the negative e�ects of synthetic larvacides is by developing biolarvacides that are safe and environmentally friendly; one of them is by using herbal materials such as papaya leaves. papaya leaves (carica papaya l) are usually used as wound healing, anti parasite, and for dengue fever. papaya leaf extract contains active ingredients such as the enzyme papain, carbaine alkaloid, and �avonoids. flavonoid compounds can a�ect the respiratory system of adult mosquitoes, papain substances can inhibit larval growth, and carpaine alkaloids are toxic to the larvae of aedes aegypti mosquitoes (govindarajan and karuppannan, 2011; wahyuni, 2015). the use of extracts still needs the development on phytopharmaca preparations because extracts are easily damaged by light, water vapor, metals, and microbes. damage to the extract can be minimized by the presence of submicron particle technology, by creating material into submicron sized particles. the submicron form has the advantages of increasing solubility, increasing stability, reducing dosage administration, increasing delivery e�ciency, and extending storage time (singh and rawat, 2017). preparation of submicron particles can utilize the biopolymeric materials such as chitosan, gelatin, albumin, and sodium alginate (han et al., 2010). the use of biopolymeric materials in https://doi.org/10.26554/sti.2019.4.3.64-69 untari et. al. science and technology indonesia, 4 (2019) 64-69 this study was a combination of chitosan and sodium alginate. the combination of chitosan with sodium alginate will form a poly ion complex (as shown in figure 1) that can entrap extract. chitosan in the form of submicron particles has the advantage of mucoadhesive which can increase the bioavailability of active ingredient (berger et al., 2004). the evaluation of submicron particle characters was observed by analyzing at the percent encapsulation e�ciency (% ee), zeta potential value, and stability test. stability parameters can be seen from the zeta potential and polydispersity index (pdi) produced. high zeta potential relates to the stability of particles. the bene�ts of this study are to provide information about; the physical interactions between papaya leaf extract to chitosan-alginate on the submicron formulation of particles; for the development of science especially in the pharmaceutical �eld for an e�ort to decrease the incidence of dengue hemorrhagic fever in indonesia. 2. experimental section 2.1 materials the materials are utilized in this research were: extract of papaya leaves (carica papaya l.) from indralaya region, some solvents with analytical grades were obtained from merck® such as ethanol, ethyl acetate, acetic acid, and hcl. pure materials were obtained from sigma-aldrich such as quercetin, chitosan, sodium alginate, calcium chloride, nacmc, sodium hydroxide and aquabidest from otsuka®. 2.2 methods 2.2.1 identi�cation of flavonoids simplicia were weighed of 0.5 g that has been crushed in a mortar and placed in a test tube, addition of 5 ml ethanol and heat were needed for 5 minutes. the extraction was �ltered and the �ltrate was obtained. then, a few drops of concentrated hcl were added and followed by enter ± 0.2 mg of magnesium powder. results that indicate the formation of red colour was used to present the �avonoids. 2.2.2 determination of the amount of total flavonoids in extracts as much as 1 g of extract was dissolved in a 25 ml volumetric �ask with 15% ethanol as much as 15 ml and stirred until homogeneous. 96% ethanol was added to the boundary mark. measurement of the absorbance of the sample was conducted at a wavelength of 374.8 nm using quercetin as marker. 2.2.3 preparation of polymers • preparation of chitosan chitosan preparation as much as 36 mg of chitosan powder was dissolved in 60 ml of 1% acetic acid solution in the cup glass then homogenized with a magnetic stirrer at a speed of 750 rpm for 30 minutes at room temperature until the dissolved chitosan solution was obtained 20 ml chitosan solution containing 12 mg for each formula. • preparation of sodium alginate preparation of 9.6 mg of sodium alginate was dissolved with 60 ml api in a beaker glass then homogenized with a magnetic stirrer at a speed of 750 rpm for 30 minutes at room temperature until the sodium alginate solution dissolved completely. the stock solution was pipetted of 20 ml (sodium alginate solution contains 3.2 mg) for each formula. • preparation of calcium chloride the 0.018 m calcium chloride concentration used in 40 �l for each formulas then was homogenized with a magnetic stirrer at a speed of 750 rpm for 30 minutes at room temperature until the solution of calcium chloride was obtained completely. 2.2.4 formula of submicron particles variation in stirring speed was used in each formula. preparation of submicron formula of chitosan and sodium alginate particles entrapping extract of papaya leaves was used the variation the concentration of calcium chloride as in table 1. the amount of extract of formula (f1, f2, f3) in this study was based on the results of the preliminary study which has the most potential to inactivated aedes aegypti mosquito larvae which used; chitosan as much as 12 mg; sodium alginate 3.2 mg and calcium chloride 18 mm of 40 �l (moradhaseli et al., 2013). table 1. formula of submicron particles entrapping extract of papaya leaf parameters amount and condition f1 f2 f3 papaya extract (ppm) 1059 1059 1059 chitosan (mg) 12 12 12 natrium alginate (mg) 3,2 3,2 3,2 cacl2 0,018 m (ml) 40 40 40 stiring (rpm) 500 750 1000 2.2.5 formation of submicron particles entrapping extract of papaya the formation of submicron particles entrapping extract of papaya leaves was conducted by using ionic gelation method as shown in figure 1. the di�erence in these three formulas was found in variations in stirring speed. the way to make a formula was as follows: ethanol extract of papaya leaves added to a 40 ml chitosan solution into a beaker glass using a magnetic stirrer with a speed of 500 rpm for each formula and as mass 1 in making submicron particles (pal et al., 2012). prepare sodium alginate solution above the magnetic stirrer with variations in the speed of 500 rpm taken 20 ml for each formula and as mass 2. perform mass mixing 1 with mass 2 by dropping it using a 50 �l micro pipette on top of the magnetic stirrer and continue to the mixing process for 1 hour with the speed of 500 rpm. the solution of calcium chloride was added with a volume of 40 �l © 2019 the authors. page 65 of 69 untari et. al. science and technology indonesia, 4 (2019) 64-69 table 2. percent ee and equivalent amount of quercetine in submicron particles formula amount %ee amount of extract amount of quercetine of extract in submicron particles in submicron particles 1 1059 mg 68.12±2.01 721.39±26.01 mg 0.3910±0.08 mg 2 1059 mg 69.07±2.68 731.45±36.41 mg 0.3964±0.15 mg 3 1059 mg 71.90±3.02 761.42±29.16 mg 0.4127±0.24 mg figure 1. ilustration of polyionic interaction between drug, alginate, and chitosan for each formula (moradhaseli et al., 2013). after mass 1 and mass 2 were mixed, then add distilled water for each formula to 100 ml. 2.2.6 puri�cation of particles and determination of percent ee submicronn particles puri�cation of sodium alginate chitosan particles encapsulated papaya leaf extract was conducted by 30 ml of the solution inserted into vivaspin® 300 kda to separate submicron particles entrapping papaya leaf extract and soluble impurities in distilled water. the centrifugation process was carried out for 15 minutes until there were 2 phases; the phase that was absorbed and the phase that was not absorbed by vivaspin® 300 kda. the un-absorbed phase was separated after added as much as 30 ml of aquadest into an absorbed phases again and centrifuged again. this treatment was done three times so that the pure papaya leaf extract particles were obtained. determination of the percent ee submicron extract of papaya leaf particles was carried out using a uv-vis spectrophotometer. the calibration curve was made in the series of concentration 0.01; 0.02; 0.03; 0.04 and 0.05 mg /ml from the quersetine stock solution with a concentration of 1 mg/ml. %ee = σacf − σacs σacf x100% (1) noted: acf : active compound of formula ; acs : active compound of supernatant 2.2.7 characterization of particles determination of particle characterization includes diameter and particle distribution was used the psa tool through the dls (dynamic light scattering). after that 50 �l of submicron solution of chitosan sodium alginate particles entrapping extract of papaya leaf was pipetted then of 50 �l and put it into cuvette. diameter and pdi measurements were carried out with a scattering angle of 90° detector. 2.2.8 fourier transform infrared (ftir) measurement the dispersed particles of the best formula and the equal amount of polymer mixture were carried out for ftir test. by measuring it was needed 5 mg mixture of sodium alginate, chitosan, with extract. as a comparison spectra, 5 mg of sodium alginate, chitosan and extract were also needed. the sample zone was carefully cleaned because this zone would be passed through an ir beam. spectra of environments were documented to minimize errors after measurements were taken. percentage (%) of intensity arranged in such a way as to rotate the stressing grid. only spectra with an intensity of 90% were documented. 2.2.9 x-ray di�raction (xrd) measurement an optimum composition of three formulas was characterized by xrd (x-ray di�raction). this measurement was needed 5 mg mixture of sodium alginate, chitosan and also extract. for comparison, 5 mg of sodium alginate, chitosan and extract were used. the sample was compacted and �attened on the aluminum holder for further measurement using the xrd tool. the scanning mode was a continuous scan on the 2� axis. 3. results and discussion 3.1 identi�cation of extract and quanti�cation of flavonoids flavonoids of extract was tested by adding mg and hcl powder to produce a reddish-orange solution that occurs due to the formation of �avillium salts (agung et al., 2017). the sample was also shown the positive saponins in the presence of stable foam which shows the presence of glycosides which are capable of forming foam in the water. the combination of structures constituent such as saponin (hydrophilic), hydrophobic groups can act as active surfaces in foam formation. positive results were obtained in tannin testing with the color change of the sample being blackish blue. the simplicia positively contains steroids in © 2019 the authors. page 66 of 69 untari et. al. science and technology indonesia, 4 (2019) 64-69 figure 2. the chemical structures of biopolymer na-alginate and chitosan the testing of steroid/triterpenoid compounds after reacted with anhydrous acetic acid and concentrated h2so4 which forms a blue acetyl steroid complex. 3.2 preparation of extract and dispersed polymers preparation of submicron particles component consists of papaya leaf extract, chitosan, sodium alginate, and cacl2, which was dissolved in the appropriate solvent. papaya leaf extract preparation was carried out by dissolving papaya leaf extract into distilled water then �ltered. chitosan powder requires 1% acetic acid for its dissolution process. 1% acetic acid solvent was chosen because chitosan dissolves in acid and acetic acid was an organic acid solvent. chitosan is also soluble in mineral acids because chitosan has an amine in acidic ph and chitosan protonated. chitosan powder is insoluble in water, concentrated alkali, alcohol and acetone. preparation of sodium alginate was carried out by means of sodium alginate powder dissolved in aquadest and cacl2 also using aquadest because it could dissolve well in water due to the presence of carboxyl groups in alginates and cl-ions on cacl2 and then interact in aquadest and then obtain clear solutions for manufacture of submicro particles of papaya leaf extract. the chemical structures of chitosan dan na-algiante was presented in figure 2. 3.3 formation of submicron particles entrapping extract of papaya the �rst stape of formation submicron particles was dissolving papaya leaf extract into aquadest then �ltered. this aims to facilitate well-mix solution. chitosan solution as mass 1 and sodium alginate as mass 2. mass 1 was added into mass 2 drop by drop to produce mass 3. drop by drop while stirring technique was used so that there was no fast-aggregation of particles and produce spheric particles. the next stape, mass 3 was sonicated using a sonicator cleaner. the sub-micro particles of the papaya leaves was obtained by adding aquabidest ad 100 ml then divided into three formulas with a volume of 10 ml. the di�erence between formulas 1, 2 and 3 was in variations in the speed of stirring using a magnetic stirrer. stirring speed in formula 1 was 500 rpm, formula 2 750 rpm, and formula 3 1000 rpm. the image of products f1, f2 and f3 was shown in figure 3. 3.4 determination of percent ee determination of percent ee (%ee) using the supernatant phase of the particle entrapping extract of papaya leaf extract was figure 3. the submicron particles of the formula (f) f1;f2;f3 figure 4. xrd spectra of a= complex(extract-biopolymer) compared to b= extract, c= chitosan, and d= na-alginate. figure 5. ftir spectra of complex, extract, na-alginate and chitosan © 2019 the authors. page 67 of 69 untari et. al. science and technology indonesia, 4 (2019) 64-69 analyzed by uv-vis spectrophotometer instrument. the %ee value obtained in formulas (f) 1, 2 and 3 were 68.12; 69.07; and 71.90 mg with no-signi�cant di�erent (p>0.5). the results of %ee was obtained in f3 have the highest %ee value so that the particles of papaya leaf extract are well protected by the sodium alginate chitosan polymer. the higher %ee value indicates that more extracts are absorbed or encapsulated by the polymer used, so that the extract content obtained is also increasing. based on the %ee obtained, the concentration of extract in each f 1, 2, and 3 was 721.39; 731.45; and 761.42 mg. quercetin content encapsulated in f 1, 2, and 3 were 0.3910; 0.3964; and 0.4127 mg quercetin. the results of the percent ee submicron particles extract of papaya leaf can be seen in table 2. 3.5 characterization of particles determination of diameter and size distribution was done using a psa tool. the samples analyzed for this test used the optimal formula, namely the f3 to determine the diameter value and particle size distribution. determination of the diameter was carried out to determine the particle size formed from the preparation of submicron particles. measurement of diameter using the psa instrument produced data of 189.2 nm. the results of diameter measurements showed that the optimal formula analyzed entered the submicron range of particles so that it was expected to increase the availability of active substances. particles size distribution parameters or pdi values were determined to detect the level of uniformity of size. particle size distribution will a�ect the stability of the particles. pdi measurements in f 3 showed a value of 0.330. 3.6 physical interaction by xrd and ftir the results of xrd measurement was displayed in figure 4 and the ftir measurement was in figure 5. the interaction study aims to determine the possibility of physical interactions between papaya extract and various polymers (chitosan and sodium alginate) without chemical shifting. determination of the presence or absence of interactions can be determined by identifying the characteristics of peaks at wave numbers in ftir and 2� in xrd. ftir spectra showed that there was a widening peak of the oh group overlapping with nh, and the presence of co groups in the spectrum which showed cooh groups. the �ngerprint area (1500 500 cm−1) which was the identity of a compound indicates the presence of co groups from cooh. according to xrd measurement, chitosan and na-alginate polymers (both of these polymers) were contacted with x-rays, as was the case with chitosan na-alginate particles entrapping papaya leaf extract as seen in figure 4. both polymers exhibit a crystal structure as in dark circles. when the polymer and papaya leaf extract become particles, there was no peak at 2� in a green circle. the results of xrd revealed the changes of type of crystalinity form to amorphous on submicron particles. 4. conclusions based on the results which has been, the summary of this research could be stated as follows: the optimum formula obtained has a speed of 1000 rpm with the %ee value of 71.90%. the results of submicron particles characterization such as diameter and particle size distribution (pdi) using particle size analyzer (psa) tools were 189.2 nm and 0.330. the results of xrd revealed the changes of type of crystalinity form to amorphous on submicron particles. the results of ftir revealed the physical interaction without chemical shifting. 5. acknowledgement the acknowledgements are addressed to sriwijaya university (unsri) for kompetitif research grant of academic year 2019 using funding of pnbp. the acknowledgements are also expressed to uii and ugm jogjakarta for helping of samples measurements. references agung, n., h. heryani, s. jae, and h. park (2017). identi�cation and quanti�cation of �avonoids in carica papaya leaf and peroxynitrite-scavenging activity. asian paci�c journal of tropical biomedicine, 7(3); 208–213 ahmad, n., h. fazal, m. bilal, h. abbasi, and i. fazal (2011). dengue fever treatment with carica papaya leaves extracts. asian paci�c journal of tropical biomedicine,, 1(4); 330–333 akerholm, m. and l. salmen (2001). interactions between wood polymers studied by dynamic ft-ir spectroscopy. polymer, 42(3); 963–969 berger, j., m. reist, j. mayer, o. felt, and r. gurny (2004). structure and interactions in chitosan hydrogels formed by complexation or aggregation for biomedical applications. european journal of pharmaceutics and biopharmaceutics, 57(1); 35–52 govindarajan, m. and p. karuppannan (2011). mosquito larvicidal and ovicidal properties of eclipta alba (l.) hassk (asteraceae) against chikungunya vector, aedes aegypti (linn.) (diptera: culicidae). asian paci�c journal of tropical medicine, 4(1); 24–28 han, j., z. zhou, r. yin, d. yang, and j. nie (2010). alginate–chitosan/hydroxyapatite polyelectrolyte complex porous sca�olds: preparation and characterization. international journal of biological macromolecules, 46(2); 199–205 jain, m., l. ganju, a. katiyal, y. padwad, k. mishra, s. chanda, d. karan, k. yogendra, and r. sawhney (2008). e�ect of hippophae rhamnoides leaf extract against dengue virus infection in human blood-derived macrophages. phytomedicine, 15(10); 793–799 kim, k., k. adachi, and y. chujo (2002). polymer hybrids of functionalized silsesquioxanes and organic polymers utilizing the sol–gel reaction of tetramethoxysilane. polymer, 43(4); 1171–1175 lin, l., w. hsu, and c. lin (2014). antiviral natural products and herbal medicines. journal of traditional and complementary medicine, 4(1); 24–35 © 2019 the authors. page 68 of 69 untari et. al. science and technology indonesia, 4 (2019) 64-69 moektiwardoyo, w., t. ami, y. susilawati, y. iskandar, o. halimah, and z. eli (2014). the potential of dewa leaves (gynura pseudochina (l) d.c) and temu ireng rhizomes (curcuma aeruginosa roxb.) as medicinal herbs for dengue fever treatment. procedia chemistry, 13; 134–141 moradhaseli, s., z. abbas, s. ali, m. nasser, s. saman, and r. mehrasa (2013). preparation and characterization of sodium alginate nanoparticle containing icd-85 (venom derived peptides). international journal of innovation and applied studies, 4; 534 – 542 natalia, n., n. lucimeire, s. santana, m. sampaio, f. maria, and l. oliva (2013). the component of carica papaya seed toxic to a. aegypti and the identi�cation of tegupain, the enzyme that generates it. chemosphere, 92(4); 413–420 singh, p. k. and p. rawat (2017). evolving herbal formulations in management of dengue fever. journal of ayurveda and integrative medicine, 8(3); 207–210 suwanbamrung, c., s. promsupa, t. doungsin, and s. tongjan (2013). risk factors related to dengue infections in primary school students: exploring students’ basic knowledge of dengue and examining the larval indices in southern thailand. journal of infection and public health, 6(5); 347–357 wahyuni, d. (2015). new bioinsecticide granules toxin from ectract of papaya (carica papaya) seed and leaf modi�ed against aedes aegypti larvae. procedia environmental sciences, 23; 323–328 zunjar, v., r. p. dash, m. jivrajani, b. trivedi, and m. nivsarkar (2016). antithrombocytopenic activity of carpaine and alkaloidal extract of carica papaya linn. leaves in busulfan induced thrombocytopenic wistar rats. journal of ethnopharmacology, 181; 20–25 © 2019 the authors. page 69 of 69 introduction experimental section materials methods identification of flavonoids determination of the amount of total flavonoids in extracts preparation of polymers formula of submicron particles formation of submicron particles entrapping extract of papaya purification of particles and determination of percent ee characterization of particles fourier transform infrared (ftir) measurement x-ray diffraction (xrd) measurement results and discussion identification of extract and quantification of flavon-oids preparation of extract and dispersed polymers formation of submicron particles entrapping extract of papaya determination of percent ee characterization of particles physical interaction by xrd and ftir conclusions acknowledgement article http://sciencetechindonesia.com article history received: 26 february 2017 received in revised form: 9 may 2017 accepted: 15 may 2017 doi: 10.26554/sti.2017.2.3.71-75 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 71-75 pillarization of layer double hydroxides (mg/al) with keggin type k4[a-siw12o40].nh2o and its application as adsorbent of procion red dye intan permata sari1, muhammad said1, aldes lesbani1* 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail : aldeslesbani@yahoo.com abstract pillarization of layered double hydroxides with polyoxometalate k 4 [α-siw 12 o 40 ]•nh 2 o at various times i.e. 3, 6, 9, 12, 24, 36 and 48 hours has been done. the pillared product was characterized by ft-ir spectrophotometer and xrd. the optimum pillared layered double hydroxides of polyoxometalate k 4 [α-siw 12 o 40 ]•nh 2 o was used as adsorbent of procion red dye. the results of characterization using ft-ir spechtrophotometer is not yet show the optimum pillaration process. the characteritation using xrd the successfully of pillared layered double hydroxides of polyoxometalate k 4 [α-siw 12 o 40 ]•nh 2 o showing the existence of diffraction angle 8.5o with intensity 355. furthermore, the pillared layered double hydroxides of polyoxometalate k 4 [α-siw 12 o 40 ]•nh 2 o with time variation of 12 hours was applied as adsorbent of procion red dye. the results show the adsorption rate was 0.523 min-1, the highest of absorption capacity at 70oc was 10.8 mol/g, the higest energy of absorption 70 oc was 125 kj/mol. the enthalpy (∆h) and entropy (∆s), decrease as the increasing consentration of procion red dye. keywords: layered double hydroxides, polyoxometalate, pillaration, procion red, adsorption introduction layered material based on his being is divided into a layered material found in nature and are synthesized. one example of a layered double hydroxide compounds synthesized double layer. hydrotalcite is layered material and has general formula [m2+ (1-x) m3+x(oh) 2 ](an-)x/n•nh 2 o, where m 2 and m 3 is divalen and trivalen metal cations and an intercultural space is filled by the compound layer hydra (zhao et al, 2011). recently, layer double hydroxides are modified by insertion or intercalation between layer using anion (maruyama et.al, 2016) or macoanion such as polyoxometalate compounds (asiabi et.al, 2017). layered double hydroxides modified with the purpose of enlarging the spacing layer so that it can be effectively used as adsorbent. modification of layered double hydroxide do with macroanion pillared process. macroanion compound used was polyoxometalate keggin type h 3 [αpw 12 o 40 ].nh 2 o. the pillared method is used on layered double hydroxide i.e. ion exchange method. pillarization of macroanion in double layers of hydroxides cause material loss of the anion oh-which located on the layer so that it is expected to enlarge the distance between layers of material layered double hydroxide (imron and said, 2017). polyoxometalates are metal oxygen clusters with various structures, acid base properties, redox properties, and also high solubility depanding on counterions (misuno, 2013). polyoxometalate is macroanions, which can be used frequently as intercalant for layer double hydroxides (omwoma et.al, 2014 ; hasannia and yadollahi, 2015). layered material is used as a catalyst, adsorbent, sensor, membrane or ion exchange. as adsorbent, a layered material used for aditive adsorption on vegetable oil, as well as its application for the control of contamination of metal ions or organic compounds in the environment. in the industrial field, most of the dyes that have been used will be discharged into the environment. generally, the dyestuff from the textile industry waste is an organic compound which has an aromatic structure so it is difficult to degrade naturally and certainly not environmentally friendly (ba-abbad, et al. 2017). this research was conducted on the synthesis and characterization of layered double hydroxides, compounds polyoxometalate k 4 [α-siw 12 o 40 ]. nh 2 o and layered double hydroxides pillared polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o. the successfully pillarization process, material was characterized using ftir and xrd analyses. furthermore, pillared material was used as adsorbent of procion red dye. procion red are toxic and difficult to degraded because it has a complex chemical structure and the presence of aromatic rings. the adsorption process was studied by adsorption time, influence of temperature and concentrations. concentration of procion red dye was determined using uv-vis spectrophotometer (zhang et al., 2012). experimental section equipments a set of standard glass tools, magnetic stirrer, thermometer, hotplates, oven, furnace, vacuum, a separator funnel, x-ray diffraction (rigaku miniflex 600), ft-ir spectrometer (shimadzu prestige-21) and uv-vis spectrophotometer (thermo scientific geneysis 20) were used in this experiment. materials chemicals to be used in this study such as sodium metasilicate (na2 sio 3 ), sodium tungstat (na 2 wo 4 ), potassium hydroxide (koh), potassium chloride (kcl), sodium hydroxide (naoh), sodium carbonate (na 2 co 3 ), magnesium nitrate (mg(no 3 ) 2 ), aluminum nitrate (al(no 3 ) 3 ), procion red (c 15 h 15 n 3 o 2 ) and water. water was supplied from intergrated research laboratory, sriwijaya university using puriteâ water filtration systems. procedure the synthesis of layered double hydroxides double layer synthesized on hydroxy solution with the concentration of each 50 ml of mg(no 3 ) 2 1 m and 20 ml of al(no 3 ) 3 1 m added to 250 ml of water and then stirred. ph of solution was adjusted to 10 using naoh and heated to the temperature of 40 oc. the reaction was kept at a ph value of 10 then added with 20 ml of na 2 co 3 2 m and 10 ml of naoh 2 m. the solution was heated to 40 oc for 3 hours and left in the oven at a temperature of 70 oc for 40 hours. the product obtained in the form of white suspension washed and dried at room temperature. the products are characterized by xrd powder analysis and ft-ir. synthesis polyoxometalate k4[α-siw12o40]•nh2o synthesis polyoxometalate k 4 [αsiw 12 o 40 ]nh 2 o synthesized by dissolving sodium metasilicate as many as 11 g in 100 ml of water used as a mailto:intandevanan08@gmail.com sari et al. 2017/science & technology indonesia 2 (3) 2017:71-75 © 2017 published under the term of the cc by nc sa 4.0 license 72 solution of as many as 182 g of sodium tungstat dissolved in 300 ml of hot water and a solution of the foundation of the solution b. as much as 165 ml of hcl 4 m added drops demi drops for 5 min with stirring with 300 rpm speed to dissolve deposits of tungstat acid. then, quickly added solution a into the solution b with the addition of 50 ml followed hydrochloric acid 4 m. the solution is kept for 1 hour at a temperature of 100 oc to the value of ph 5 to 6. as many as 50 ml and 80 ml sodium tungstat hydrochloric acid 4 m is added into the solution quickly. this solution is difiltrasi after it is cooled at room temperature. the solution used to obtain salt or acid [α-siw 12 o 40 ]4-.nh 2 o. the potassium salt is obtained by adjusting the ph value of the solution at 2 using potassium chloride by as much as 50 g quickly to white from salt deposits acquired potassium form k 4 [α-siw 12 o 40 ].nh 2 o characterization of compound was done using ftir spectroscopy and xrd analysis. preparation of layered double hydroxides pillared polyoxometalate k4[αsiw12o40]•nh2o the process pillarization of layered double hydroxides by polyoxometalate was conducted using ion exchange method. reactions is done by making the solution a, polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o as much as 1 g with 50 ml water 100 ml in beaker and solution b, 1 g of double layer in hydroxides was placed into beaker and added 25 ml of 1 m sodium hydroxide. solution a and solution b was mixied together in one neck round bottom flask with the stirring speed 280 rpm in irrigated conditions gas n 2 in order not going direct contact with oxygen in the air while using magnetic stirring in stirer with variations in time. the determination of the variation of time starting from 3, 6, 9, 12, 24, 36, and 48 hours. this suspension is cooled and washed with water and dried at room temperature. characterization was performed using xrd powder and ft-ir analyses. application of pillared material as adsorbent of procion red effect of adsorption time as much as 2 g pillared material was mixed with 50 ml of procion red with concentration concentration of 25 mg/l. the mixture is then stirred using a horizontal shaker at the appointed time. as control, in a different container as much as 2 grams of non pillared material was applied. variation of time was 10, 20, 30, 40, 50, 60, 70, 80 and 90 minutes. procion red and adsorbent was separated by filtration then concentration was measured by using uv-vis spectrophotometer. adsorption rate can be calculated using equation (1). effect of concentration and temperature adsorption influence of thermodynamic adsorption of procion red adsorption on pillared material was done through a series of experiments by varying the concentration of procion red and temperature. as much as 2 g of adsorbent was mixed with 50 ml of solution of procion red (10, 25, 50, 100 mg/l) while stirring using a horizontal shaker for 1 hour at a temperature that varies (30, 40, 50, 60, 70, and 80 oc). as control, in a different container as much as 2 g of layer double hydroxides was interacted with 50 ml of procion red substances (10, 25, 50, 100 mg/l). the mixture was filtered, then a solution of procion red which has been separated from the adsorbent was measured using a uv-vis spectrophotometer to know the concentration of residual concentration of procion red. adsorption capacity and energy can be calculated using the equation of langmuir in equations (2) and (3), whereas the entropy and enthalpy adsorption can be calculated using equation (4). data analysis the pillared layer double hydroxides was characterized using ft-ir and xrd analyses. basal spasing value can be obtained based on xrd pattern and it is expected that the pillared material has a layer between layers larger than before the process of pillarization. pillared material was used as adsorbent of procion red. the adsorption process was studied through kinetic and thermodynamic parameters. the adsorption kinetic was studied by variation of adsorption time and adsorption rate calculated based on langmuir heinselwood adsorption equation as follows: 1 ln( )occ tk k c c = + (1) where: c0 = the initial concentrations procion red c = concentrate procionred after time t = adsorption time k = adsorption equilibrium constant the thermodynamic parameters were studied through variations in the concentration of procion red dye and temperature. adsorption capacity and energy were calculated on the basis of the langmuir equation as follows: 1c c m bk b = + (2) lne rt k= − (3) where: c = procion red concentration after adsorption reaches equilibrium m = mol of procion red adsorbed at 0.5 grams adsorbent k = equilibrium constant b = adsorption capacity e = adsorption energy r = constant t = temperature while to find the value of coefficient of adsorbat distribution used equation as follows: ln s h kd r rt ∆ ∆ = − (4) where: kd = coefficient of adsorbate distribution (qe/ce) δh = enthalpy δs = entropy r = constant t = temperature figure 1. ftir spectra of layer double hydroxides. figure 2. ftir spectra of polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o. wavenumber (1/cm) wavenumber (1/cm) sari et al. 2017/science & technology indonesia 2 (3) 2017:71-75 © 2017 published under the term of the cc by nc sa 4.0 license 73 results and discussion characterization of layer double hydroxides and pillared layer double hydroxides with polyoxometalate using ftir spectrophotometer characterization using ft-ir spectrophotometer resulted in ir spectrum of layer double hydroxides and pillared layer double hydroxides at various temperatures as seen in figure 1, 2, and 3. it can be seen in figure 1 that the broad vibration peak between the wavenumber 3800-3300 cm-1 is assigned as the vibration of the oh group in the structure of the layer double hydroxides (zvezdova, 2014). the peak at the wavenumber 1635 cm-1 is a bending of oh vibration. the wavenumber at 1381 cm-1 is assigned as vibration of stretching of nitrate. bending vibration of nitrate was also detected at wavenumber 671 cm-1. vibration of al-o and mg-o were appeared at wavenumbers 601 cm-1 and 408 cm-1. ftir spectrum of polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o as shown in figure 2 shows the unique vibration of si-o at 925.83 cm-1. the vibration of w = o was detected at 979.84 cm-1. the wavenumber at 879.54 cm-1 shows the presence of oxygen w-oe-w vibrations located on the edge of the polyoxsometalate k 4 [α-siw 12 o 40 ].nh 2 o. peak at 779.24 cm-1 shows the vibration of the w-oc-w group, where an oxygen atom located at the center of the polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o compound. the double layer hydroxide was then pillarized with a poloxometalate k 4 [α-siw 12 o 40 ].nh 2 o by an aqueous solution wherein the double layer hydroxides was dissolved with naoh and the polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o was dissolved with water. the weight ratio of layer double hydroxides: polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o was 1: 1. variation of pillarization time was 3, 6, 9, 12, 24, 36 and 48 hours. the ftir spectrum of layer double hydroxides pillared with polyoxometalate k 4 [α-siw 12 o 40 ]. nh 2 o compound was shown in figure 3. ftir spectrum in figure 3 showed that almost vibrations are similar at various pillarization times. pillarization at 3-24 hours give dominant vibration of layer double hydroxides, while pillarization at 36-48 hours resulted almost ir spectrum of polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o. due to unclear results to determine optimal pillarization process, further characterization was conducted using xrd powder analysis. characterization of pillared layer double hydroxides using xrd powder analysis. the xrd powder pattens of layer double hydroxides pillared with polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o at various time was shown in figure 4. the variation of pilaration time is expected to obtain the best diffraction showing the diffraction of a pillared polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o to layer double hydroxides. diffraction of polyoxometalate at 6-10°, 15-20°, 22-25°, and 35-40° is emphasized to determine the successful pilarization process yang et al (2011). on the other hand, diffraction of layer double hydroxides at 10o and 60o is not affected to the pillarization process (dolidovich and palkovits, 2015; shan et.al, 2014). diffraction at of 60o indicating that the presence of anions on the interlayer may be anion nitrate, carbonate, or other anions (kuang et.al, 2010; aviles et.al, 2015). the xrd patterns of pillarization at 3 hours, 6 hours and 9 hours showed there was a peak at an angle of 6-10o with a small intensity. whereas in the 12 hours pillarization shows characteristic of the pillarized polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o at the diffraction angle 8.5o with figure 3. ft-ir spectrum of layered double hydroxides pillared with polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o at 3 hours (a) ,6 hours (b), 9 hours (c), 12 hours (d), 24 hours (e), 36 hours (f) and 48 hours (g). figure 4. xrd powder patterns of layer double hydroxides pillared with polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o at 3 hours (a), 6 hours (b), 9 hours (c), 12 hours (d), 24 hours (e), 36 hours (f), and 48 hours (g). figure 5. effect of procion red adsorption time using layer double hydroxide and pillared layer double hydroxides at 12 hours. wavenumber (1/cm) diffraction angel (degree) sari et al. 2017/science & technology indonesia 2 (3) 2017:71-75 © 2017 published under the term of the cc by nc sa 4.0 license 74 a intensity of 353.5. pillarization time at 36 hours and 48 hours showed that there is no peak in the region of 6-10° which is characteristic of the k 4 [α-siw 12 o 40 ].nh 2 o. from this diffraction data, it can be seen that the 12 hours pillarization time has a diffraction angle of 6, 10, 35 and 40° which is characteristic of layer double hydroxides pillared compound. other pillarization time at 3 hours, 6 hours, 9 hours, 24 hours, 36 hours and 48 hours does not show any diffraction at 6°. thus, the optimal pillarization of layer double hydroxides with polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o was achieved at 12 hours. futher experiment was used layer double hydroxides pillared polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o at 12 hours as adsorbent of procion red dye in aqueous medium. effect of adsorption time on adsorption of procion red using layer double hydroxides and pillared material layer double hydroxides pillared with polyoxometalate k 4 [α-siw 12 o 40 ]. nh 2 o can absorb more adsorbate than double layer hydroxide material at the same time as shown in figure 5. the optimum absorption occurs in the layer double hydroxides as control which absorbs the procion red dye shown by the blue curve at 50 minutes with absorption of 32.69 ppm from the initial concentration of 60 ppm. on the other hand, adsorption of pillared material reached more than 70 ppm at the same time with layer double hydroxides. the adsorption patterns of layer double hydroxides and pillared material have similar style. adsorption was slow at initial time and reach equilibrium at around 70 minutes. layer double hydroxides pillared polyoxometalate k 4 [α-siw 12 o 40 ].nh 2 o compound showed the optimum adsorption at 20 minutes with adsorption of 57.45 ppm from initial concentration of 100 ppm. by increasing adsorption time will increase the amount procion red adsorbed. adsorption was almost constant at 50 minutes. both physisorption and chemisorption will give similar trend for adsorption by increasing adsorption time (yu, et al., 2015). the data was obtained in table 1 show that layer double hydroxides pillared with k 4 [α-siw 12 o 40 ].nh 2 o has adsorption rate faster than adsorbent before pillarization. probably due to of layer activity after pillarization can create reactivity of pillared layer double hydroxides. effect of concentration and temperature adsorption of procion red using layer double hydroxides and pillared material as adsorbent. figure 6 and 7 show the effect of temperature and concentration of procion red on layer double hydroxides and pillared material. these results in general shows that the higher the temperature can create the greater of procio red adsorbed. the greater concentration of procion red also will increase the amount of procion red adsorbed. these phenomena was equal for both layer double hydroxides as adsorbent as shown in figure 6 and layer double hydroxides pillared k 4 [α-siw 12 o 40 ].nh 2 o as shown in figure 7. figure 6 and 7 shows that there is an adjacent point at the concentration of procion red 10 mg/l and 20 mg/l due to increasing termperature did not increased the adsorption of procion red. the highest adsorption was reached at temperature 70 oc for both layer double hydroxides and pillared material. by increasing concentration of procion red was also increased the adsorption of procion red but at concentration 30 and 50 oc there was a path of adsorption on pillared layer double hydroxides. probably due to interlayer activity caused unstability of pillared layer double hydroxides. the adsorption capacity and energy of the procion red dye adsorption on layer double hydroxides and pillared layer double hydroxides were obtained from equation 2-4 and the results are presented in table 2. in general, adsorption capacity and energy were increased by increasing temperature (vimoses et al, 2009). in contrast, adsorption capacity of procion red on pillared layer double hydroxides was lower than layer double hydroxides. this phenomena is due to unstable pillared layer double hydroxides toward procion red and also molecular size of procion red is larger than interlayer distance material after pillarization. the further thermodynamic parameters are enthalpy (δh) and entropy (δs) of the procion red dye adsorption on layer double hydroxides and pillared material as shown in table 3. the thermodynamic parameter in table 3 showed that irregular data. as explained above due to unstable pillared layer double hydroxides toward procion red dye caused enthalpy and entropy can be predicted by increasing temperature and concentration of procion red. figure 6. effect of temperature and concentration of procion red on layer double hydroxides figure 7. effect of temperature and concentration of procion red on layer double hydroxides pillared k 4 [α-siw 12 o 40 ].nh 2 o table 2. adsorption capacity and energy of procion red dye on layer double hydroxides and pillared material. adsorbent temp. (oc) b (mg/g) e (kj/mol) layer double hydroxides 30 28.5 9.04 40 27.02 8.69 50 90.90 11.07 60 111 11.13 70 125 10.8 pillared 30 41.1 18.5 40 46.7 15.3 50 16.8 10.9 60 2.99 2.95 70 16.8 1.59 tabel 1. the adsorption rate of procion red on layer double hydroxides and pillared material. adsorbent parameter k 1 (minutes-1) r2 layer double hydroxides 0.302 0.666 pillared 0.523 0.569 sari et al. 2017/science & technology indonesia 2 (3) 2017:71-75 © 2017 published under the term of the cc by nc sa 4.0 license 75 table 3. the enthalpy value (δh) and entropy (δs) of procion red dye adsorption on layerv double hydroxides and pillared material adsorbent co r2 δh (kj/mol) δs (kj/mol) layer double hydroxides 20 0.821 -5004 182.2 30 0.948 -3505 123.7 40 0.957 -2536 93 50 0.948 -2994 107 60 0.972 -2260 79.79 pillared 20 0.048 -4461 0.136 30 0.946 -2689 99.1 40 0.929 -1363 50.87 50 0.990 -1215 46.25 60 0.848 -1399 49.82 conclussions pillared layer double hydroxides with k 4 [α-siw 12 o 40 ]•nh 2 o was successfully conducted, which was identified from xrd analysis. xrd patterns showed optimal pillarizationresults at 12 hours by indicating the presence of double layer hydroxy material at 60, 100, and 350 diffraction angles and in regions 60 – 630 indicated the existence of pillarization process. the optimum adsorption of procion red was occurred at 20 minutes with adsorption of 57.45 ppm from initial concentration of 100 ppm. procion red adsorption using pillarized compound resulted in adsorption rate (k) of 0.523 min-1, while the influence of temperature and concentration of adsorption capacity is greatest at temperature 70 oc. the largest adsorption energy at 70oc is 125 kj/mol, and for entropy (δs) and enthalpy (δh) decreases with increase of dye concentration. acknowledgement authors thank to sriwijaya university for support of this research through “hibah profesi 2017 to a.l. references asiabli. h., yamini. y., shamsayei. m., tahmasebi. e. 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(2014). preparation, characterization and adsorption properties of chitosan nanoparticles for congored as a model anionic direct dye. naccni trudove na rusendev university, 53, 83-87. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 3, july 2021 research paper determining the credit score and credit rating of firms using the combination of kmv-merton model and financial ratios norliza muhamad yusof1*, iman qamilia alias1, ainee jahirah md kassim1, farah liyana natasha mohd zaidi1 1faculty of computer and mathematical sciences, uitm, cawangan negeri sembilan, kampus seremban, 70300 seremban, negeri sembilan, malaysia *corresponding author: norliza3111@uitm.edu.my abstract credit risk management has become a must in this era due to the increase in the number of businesses defaulting. building upon the legacy of kealhofer, mc�own, and vasicek (kmv), a mathematical model is introduced based on merton model called kmv-merton model to predict the credit risk of firms. the kmv-merton model is commonly used in previous default studies but is said to be lacking in necessary detail. hence, this study aims to combine the kmv-merton model with the financial ratios to determine the firms’ credit scores and ratings. based on the sample data of four firms, the kmv-merton model is used to estimate the default probabilities. the data is also used to estimate the firms’ liquidity, solvency, indebtedness, return on asset (roa), and interest coverage. according to the weightages established in this analysis, scores were assigned based on those estimates to calculate the total credit score. the firms were then given a rating based on their respective credit score. the credit ratings are compared to the real credit ratings rated by malaysian rating corporation berhad (marc). according to the comparison, three of the four companies have credit scores that are comparable to marc’s. two a-rated firms and one d-rated firm have the same ratings. the other receives a c instead of a b. this shows that the credit scoring technique used can grade the low and the high credit risk firms, but not strictly for a firm with a medium level of credit risk. although research on credit scoring have been done previously, the combination of kmv-merton model and financial ratios in one credit scoring model based on the calculated weightages gives new branch to the current studies. in practice, this study aids risk managers, bankers, and investors in making wise decisions through a smooth and persuasive process of monitoring firms’ credit risk. keywords credit score, kmv-merton model, financial ratios, credit rating, default, credit risk received: 9 february 2021, accepted: 10 june 2021 https://doi.org/10.26554/sti.2021.6.3.105-112 1. introduction recent statistics by kraemer (2020) revealed that 2019 is the most challenging year compared to the previous years as the number of �rms bankruptcies rose. a rare default case occurred after the investment-grade (high) rated �rms were reported to default. the �rms’ failure to pay debts will a�ect the organization in the �rms themselves and lenders and the economy. therefore, practical credit risk assessment is a must to curb the risk transmission. credit scoring is a perfect example of one of the methods to grade �rms’ credit risk. the literature of credit scoring is very limited and only starts to be widely used from the 21st century especially for consumer lending (abdou and pointon, 2011). credit scoring contains elements that are quantitative and qualitative (haralambie et al., 2016). the qualitative part can be done based on judgemental, but the essential factor is the quantitative part where empirical criterion can be obtained statistically or mathematically (chijoriga, 2011). in this research, credit scoring is done quantitatively based on the kmv-merton model and �nancial ratios. commonly, kmv-merton model is used to predict the probability of default of �rms. this includes studies from (crosbie and bohn, 2019; vassalou and xing, 2004; zhang et al., 2010; bharath and shumway, 2004; kollár and gondžárová, 2015). meanwhile, the �nancial ratios are needed to evaluate �rms’ liquidity, solvency, leverage, and pro�tability as done by (altman, 1967; beaver, 1966; zorn et al., 2018). however, (bharath and shumway, 2004) demonstrated that the use of the kmvmerton model is inadequate as a default forecaster. thus, some �nancial ratios were recommended to improve the kmv-merton model’s performance (liang, 2012). a few researchers such as benos and papanastasopoulos, 2007; liang, 2012; andrikopoulos and khorasgani, 2018 focused on incorporating the �nancial ratios with the kmv-merton model to improve the accuracy of their default prediction. most https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.3.105-112&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.3.105-112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 figure 1. the research process of the study of the researchers used both the kmv-merton model and �nancial ratios to produce a hybrid default model. contradicted to this research where the kmv-merton model is combined with the �nancial ratios into one credit scoring formula to determine the credit ratings of �rms. in this credit scoring model, the weightage of each �nancial ratio and kmv-merton model are calculated based on certain criteria. therefore, this research aims to determine the credit score and credit ratings of the selected �rms using the combination of the kmv-merton model and �nancial ratios. this research presents the other view to credit scoring that employs the kmv-merton model and �nancial ratios to assess a �rm’s credit risk. in addition, comparisons are made between the credit ratings measured in this research and the marc credit ratings. the following is how the rest of the paper is organized: the second section explains the research methods, including data setting, default probability estimations, calculating weightages and credit scores, and assessing �rm credit ratings. the �ndings of this study were discussed in the third part. lastly is the conclusion. 2. methodology the process of this study is presented in term of �owchart as in figure 1. all the process are explained in detail in the following sub-sections. 2.1 data setting samples of four �rms’ �nancial data: sime darby plantation, tenaga nasional berhad (tnb), alam maritim resources berhad, and press metal berhad are used in this study. based on marc’s credit ratings, these four �rms were chosen to represent the strong, medium, and bad rated �rms. all data was gathered according to the year in which the credit rating was published from 2014 to 2019. the data is obtained from the �rms’ annual report, including current assets, current liabilities, total equity, total liabilities, total assets, net pro�t, earning before net interest, and interest expenses. table 1 describes the descriptive statistics of data obtained from the �rms’ annual report. these data are used to calculate the �nancial ratios of the �rms, as presented in table 3. table 3 shows the selected �nancial ratios and their formula based on (caracota et al., 2010). liquidity refers to a �rm’s ability to repay its short-term debt (yameen et al., 2019). next, when dealing with the banking sector, solvency is used to assess a �rm’s viability (zorn et al., 2018). the term "indebtedness" refers to a �rm’s willingness to carry debt and ful�l its obligations (gibson, 1987). meanwhile, return on asset (roa) is a metric that calculates how pro�table a �rm is as a result of its assets (rosikah et al., 2018). finally, interest coverage is used to assess a �rm’s ability to pay interest (nwanna and ivie, 2017). there are �ve ratios involved, and they are liquidity, solvency, indebtedness, return on assets (roa), and interest coverage (time interest earned). the data from the �rms’ quarter report that includes the short-term and long-term borrowings are used to de�ne the book value of liabilities. this study also utilized the outstanding shares obtained from the quarterly report and the historical daily price obtained from finance, 2020; investing, 2020. the shortterm borrowings, long-term borrowings and the outstanding share are assumed �xed according to the quarter reports. table 2 describes the descriptive statistics of data obtained from the �rms’ quarterly report. this data was set up as a process to estimate �rms’ default probabilities. 2.2 estimating the default probabilities of firms using the kmv-merton model kmv-merton model is the extended model of the merton (1974) model where a new parameter called distance to default (dd) is introduced in this model. default occurs when the �rm’s market value of the asset falls below the default point, de�ned as the �rms’ book value of liabilities (crosbie and bohn, 2019). there are �ve steps involved to estimate the probability of default of �rms using the kmv-merton model. the �rst step is to calculate the daily market value of �rms’ equity by multiplying each of the daily prices with the outstanding shares. the second step is to calculate the daily book value of liabilities, d by de�ning it as a total borrowing of the short term plus half of the long-term borrowings. one-half of the liabilities are used, as the default point usually lies between total liabilities and current liabilities (crosbie and bohn, 2019). the third step is to add together the �rms’ market value of equity and the book value of liabilities to get the daily asset’s market value, vt . the fourth step is to generate the daily natural log of the assets’ market values returns, ln(vt /vt−1) . here, the average return, � and the standard deviation, � are calculated as the �rms’ expected © 2021 the authors. page 106 of 112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 table 1. the descriptive statistics of data obtained from the firms’ annual report item (rm) descriptive statistics n minimum maximum mean std. deviation current asset 4 1,669,956,000 278,540,906,000 77,601,969,750 134,390,656,391 current liabilities 4 2,072,044,000 252,381,385,000 70,628,376,750 121,561,848,422 equity 4 597,127,000 59,282,100,000 19,480,180,500 27,405,184,942 total liabilities 4 151,297,000 45,411,700,000 13,914,587,250 21,239,042,871 total assets 4 870,890,000 178,847,200,000 53,420,926,250 84,487,428,574 net pro�t 4 -145,380,000 4,529,200,000 1,192,855,000 2,230,747,917 earning before net 4 -138,897,441 8,206,800,000 2,226,447,64 3,995,582,703 interest expenses 4 6,654,090 1,487,700,000 389,511,523 732,403,723 table 2. the descriptive statistics of data obtained from the firms’ quarterly report item (rm) descriptive statistics n minimum maximum mean std. deviation outstanding share 16 257,869,000 6,885,000,000 3,458,423,438 2,961,295,203 short term borrowing (rm) 16 89,363,000 6,061,000,000 2,209,695,813 1,891,270,258 long term borrowing (rm) 16 15,016,000 43,737,900,000 11,921,773,688 18,723,901,636 returns and daily volatility, respectively. since asset returns follows the random walk properties and probability of default is estimated annually, thus the daily volatility is annualized by multiplying it by the square root of trading days, which is 252 days in a typical year (glenn, 2018). the �fth step is calculating the distance to default, d using the following equation: d = ln(vtd ) + (� − �2 2 )t t√� (1) the parameter d is de�ned as the number of standard deviations away from default (crosbie and bohn, 2019) where vt is the market value of the asset at any time t, d is the book value of liabilities, � is the expected asset returns, � is the asset volatility and t =1 year. finally is to estimate the annual default probability of the �rms. merton, 1974 assumed that the asset returns’ random component is normally distributed. thus, the probability of default, pt , is written in term of standard cumulative normal distribution function and it is de�ned as the inverse of d expressed as follows: pt = 1 − p(z < d) = p(z < −d) = ∫ −d −∞ e− 1 2 z 2 dz (2) a �rm is said to have a higher default probability as the value approaching one, and a lower default probability as the value is approaching 0. the larger the distance to default, the lesser the �rm’s probability to default. 2.3 calculating the weightage of default probability and financial ratios calculating weightage is essential to determine the weightage of each �nancial ratio and default probability according to speci�c criteria in credit scoring. all the �ve �nancial rat ios (x1,x2,x3,x4,x5) used in table 3 and the default probability (pt) are denoted as the credit risk indicators i = pt ,x1,x2,x3,x4,x5. the formula used to calculate the weightage of each credit risk indicators i, wi, is presented as: wi = si ∑6i=1 si (3) given si is the score of each credit risk indicator i, and it is calculated based on the approach of o’loughlin (2009) as expressed below: si = 8 ∑ j=1 wjsj (4) where j is the eight criteria shown in table 4. hence, wj is the weight to criteria and sj is the criteria score that is determined in this study. there are eight criteria de�ned by o’loughlin (2009) in the weighted scoring model, which are value, risk, urgency, stakeholder, success, di�culty, relationship, and compliance. each criterion has been given its own percentage, wj, as shown in table 4. the value and risk represent the accuracy of the credit risk indicators and the ability to measure risk, respectively. urgency shows the ability to alert the �rms on taking immediate action in any case of a default event. a stakeholder is where there is any © 2021 the authors. page 107 of 112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 table 3. the financial ratios (caracota et al., 2010) no. financial ratios formula 1 liquidity, x1 current assetscurrent liabilities 2 solvency, x2 equitytotal liabilities 3 indebtedness, x3 total liabilitiesequity 4 return on asset (roa), x4 net pro�ttotal assets 5 interest coverage (time interest earned), x4 earning before net interest, costs, and taxinterest expense table 4. the score weightage criteria, j weight to criteria wj criteria score, sj pt x1 x2 x3 x4 x5 value 20% 9 4 7 9 6 6 risk 20% 9 5 8 8 7 8 urgency 15% 9 7 8 8 7 7 success 10% 6 6 7 6 8 8 compliance 5% 7 2 6 6 2 2 relationships 5% 9 4 9 9 4 8 stakeholder 15% 4 5 4 8 9 7 di�culty 10% 7 4 4 4 4 4 score, si 7.65 4.90 6.65 7.55 6.50 6.60 weightage, wi (%) 100 19 12 17 19 16 17 table 5. the scoring of probability of default (credit, 2014) default probability, pt (%) score, k 0.00-0.12 10 0.12 – 0.27 9 0.27-0.34 8 0.34 – 0.55 7 0.55 – 0.87 6 0.87 – 1.40 5 1.40 – 2.10 4 2.10 – 4.00 3 4.00 – 9.99 2 9.99 – 50.00 1 50.00 – 100 0 involvement between the credit risk indicators and stakeholders. success describes the success of credit risk indicators to measure the �rm’s �nancial performance. di�culty relates to how the model acquires its needed parameters. the relationship criterion shows how the models have any relation to credit risk. lastly, the compliance measures the level of the credit risk indicators in conforming to any related law. the criteria scores, sj is set up in this study based on the importance and relevancy of the credit risk indicators i in ful�lling the criteria. its score can be in the ranges extremely important (9 to 10), averagely important (6 to 8), and least important (0 to table 6. the scoring of financial ratios (caracota et al., 2010) financial ratios ratio score, k liquidity x1 ≥ 1.3 7 1.1 ≤ x1 < 1.3 5 1 ≤ x1 < 1.1 3 0 ≤ x1 < 1 1 solvency x2 ≥ 0.1 9 0.07 ≤ x2 < 0.1 6 0.05 ≤ x2 < 0.07 3 x2 < 0.05 0 indebtedness 0 ≤ x3 < 2 6 2 ≤ x3 < 4 5 4 ≤ x3 < 6 3 x3> 6 0 roa x4 ≥ 0.05 2 0 < x4 < 0.05 0 interest coverage x5 ≥ 0.03 10 0.02 ≤ x5 < 0.03 8 0.01 ≤ x5 < 0.02 5 x5 < 0.01 0 © 2021 the authors. page 108 of 112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 5). for example, as shown in table 4, the probability of default is scored as 9 for the value criterion. it is scored as extremely important because the probability of default value is considered a signi�cant value that could predict �rms’ default (liang, 2012). the probability of default is shown to score the highest in almost all the criteria, corresponding to its importance for this research. there is an exception in the stakeholder criterion. usually, stakeholders are concerned about the �rm’s pro�t and its consistency with the revenue stream. the roa is the most preferred by the stakeholders as they measure the �rm’s pro�tability. thus roa scored the highest. the results of implementing the equations (3) and (4) are given in table 4. table 4 presents the score weightage of the credit risk indicators i. 2.4 calculating the credit score of firms this part is where the combination of the kmv-merton model and �nancial ratios took place, as all the scores were added into one formula to determine the credit score of the selected �rms. the credit score of the �rms, f is determined based on the following equation expressed as (chikomba et al., 2013): f = 6 ∑ i=1 wi( ki max ki ) (5) where wi is the weightage of the credit risk indicators i calculated using equation (3). meanwhile ki is the score assigned as the default probability and �nancial ratios were estimated and then mapped into tables 5 and 6. tables 5 and 6 show the score given for the default probability and �nancial ratios. the max ki is the maximum score that can be obtained for the default probability and �nancial ratios as given in tables 5 and 6. the scores given in tables 5 and 6 were assigned by (credit, 2014; caracota et al., 2010) to indicate the strength of �rms based on a certain level of credit risk. in this case, the worst score given is zero, while the excellent score can be varied from two to ten. table 7. the credit rating maps to the credit score (chikomba et al., 2013) credit score, f (%) credit rating level of credit risk 75 – 100 a low 60 – 74 b medium 50 – 59 c high 25 – 0 d default 2.5 determining the credit rating of the firms the �rms’ credit rating can be determined by comparing the calculated �rms’ credit scores with table 7. table 7 presents the credit rating maps to the credit score. the last step is comparing the credit ratings determined with the ratings given by the marc. beforehand, some adjustment is made to standardize marc’s credit rating as presented in table 8. table 8. credit ratings equivalent to marc ratings credit rating marc rating a aaa,aa,a b bbb,bb,b c c d d 3. results and discussion 3.1 the default probabilities and financial ratios in this study, the default probabilities of the four �rms are calculated using equation (2) of the kmv-merton model, as described in section 2.2. in the meantime, the �nancial ratios are determined using the formula in table 3. tables 9 and 10 show the results of implementing the equation and the formula. table 9 presents the results of estimating the �rms’ default probabilities using the kmv-merton model. based on the asset and liabilities values given in table 9, the leverage ratio (book value of liabilities / market value of asset) is calculated to measure �rm’s �nancial leverage. sime darby plantation has the lowest leverage ratio of 0.12, which is followed by tnb (0.24), alam maritim (0.45), and press metal (0.77). leverage ratio indicates how much of a �rm’s capital is funded by debt. the press metal borrowed 77 percent of its money, while alam maritim borrowed nearly half. sime darby plantation and tnb, on the other hand, only used 12 percent and 24 percent of their resources in the form of debt, respectively. the amount of permissible leverage, on the other hand, is determined by the sector in which the �rm work. some businesses are prone to taking on a lot of debt. as a result, other factors such as the anticipated return must be considered. based on table 9 only the sime darby plantation is expected to have a positive return while others have negative returns. in terms of volatility, the asset of press metal is the most volatilized, and next is the alam maritim, sime darby plantation, and tnb. these are parallel where �rms with higher asset volatility tend to have a lesser amount of leverage ratio (patel and pereira, 2007). considering all these, sime darby plantation is predicted to have the highest dd, while the press metal is expected to have the lowest dd. therefore, the pd of the sime darby is the lowest, followed by tnb. still, both have approximately 0% of pd. then, the value of pd goes higher to 4% for alam maritim and even higher than 42% for press metal. table 10 shows the �nancial ratios estimated for the selected �rms. alam maritim is found to have the highest liquidity and solvency among all the �rms and the lowest indebtedness, roa, and interest coverage. this contradicted the press metal, where it has the lowest liquidity and solvency but the highest indebtedness, roa, and interest coverage. instability in these �nancial ratios of both �rms showing a sign of poor �nancial performance. although alam maritim has the highest liquidity and solvency, it has problems paying debt and gaining pro�t. meanwhile, press metal has problems countering its assets over its liability and has the lowest viability even if it can pay its debt. unlike the © 2021 the authors. page 109 of 112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 table 9. the result of estimating the �rms’ default probabilities using the kmv-merton model sime darby tenaga nasional alam maritim press metal plantation berhad (tnb) resources berhad berhad market value of asset (rm’000) 42640750 99853648 304671 2214991 book value of liabilities (rm’000) 5117500 24445500 138268 1703075 expected return 0.0006711 -0.0000698 -0.000712 -0.000034 asset volatility 0.2016 0.1493 0.4041475 0.5659 distance to default (dd) 10.4169 9.3502 1.751 0.1814 probability of default (pd) 1.04e-25 4.37e-21 4.00e-02 4.28e-01 table 10. the financial ratios of firms sime darby tenaga nasional alam maritim press metal plantation berhad (tnb) resources berhad berhad liquidity 1.0435 1.0820 1.1037 0.8059 solvency 2.0479 1.3054 3.9467 0.9278 indebtedness 0.4883 0.7660 0.2534 1.0778 return on asset 0.0043 0.0253 -0.1669 0.0487 interest coverage 7.7993 5.5164 -20.8740 36.5553 table 11. the credit score of the firms credit risk weightage, wi (%) max ki score, ki sime darby tenaga nasional alam maritim press metal plantation berhad resources berhad berhad pt 19 10 10 10 2 1 x1 12 7 3 3 5 1 x2 17 9 9 9 9 9 x3 19 6 6 6 6 6 x4 16 2 0 0 0 0 x5 17 10 10 10 0 10 credit score, f (%) 100 77 77 48 57 table 12. the comparison of the credit rating and marc rating firm credit score, f (%) credit rating marc rating sime darby plantation 77 a a tenaga nasional berhad 77 a a press metal berhad 57 c b alam maritim resources berhad 48 d d © 2021 the authors. page 110 of 112 yusof et. al. science and technology indonesia, 6 (2021) 105-112 sime darby plantation and tnb, where their �nancial ratios are more stable. 3.2 credit score and credit rating the credit score of the �rms is calculated using equation (5), where the weightage of the default probability and �nancial ratios are determined beforehand using equations (3) and (4). then, the credit ratings of the �rms are determined according to the score obtained using table 7. tables 11 and 12 presents the results of calculating the credit score and the determining the credit ratings, respectively. table 11 shows the credit score of �rms. a larger score means the �rms have better �nancial performances. based on tables 9 and 10, we found that sime darby and tnb can be categorized as �rms with low default risk and stable �rms, and thus, both �rms were given maximum scores in pd and three out of �ve �nancial ratios. this is contradicted to the alam maritim, where it only scored maximum in solvency and indebtedness. the same goes for press metal with the addition of maximum score in interest coverage. none of the �rms obtained the maximum score in liquidity and roa. as a result, the �nal credit score for sime darby plantation and tnb (77%) are the highest, followed by press metal (57%) and lastly alam maritim (48%). this can also be seen clearly in table 12. table 12 presents the comparison of the credit rating and marc rating. sime darby plantation and tnb were rated a, while alam maritim was rated d. only press metal rating does not match with the marc ratings as press metal was rated c instead of b. 4. conclusions in this research, a method for determining a �rm’s credit score is presented to grade the credit risk of the �rms, which uses a combination of the kmv-merton model and �nancial ratios corresponding to the certain weightage. four �rms have been selected: sime darby plantation, tenaga nasional berhad, alam maritim resources berhad, and press metal berhad. these �rms’ �nancial data was utilized to estimate the �rms’ pd, liquidity, solvency, indebtedness, pro�tability, and interest coverage. we found that higher asset to debt ratio, higher returns, and lower volatility estimates higher dd and, thus, lower pd. meanwhile, higher liquidity, solvency, pro�tability, interest coverage, and lower indebtedness estimate better �nancial performance. based on these results, sime darby plantation and tnb are found to have a low default risk and secure �nancial account compared to the alam maritim and press metal. this is seen as the credit score determined for both sime darby plantation and tnb is 77%, followed by press metal 57% and alam maritim 48%. those scores bring sime darby plantation and tnb as a-rated �rms and alam maritim as a d-rated �rm, while ratings for press metal are between b-rated and c-rated �rms. overall, a combination of both �nancial ratios and the kmv-merton model in credit scoring is one of the valuable way of measuring credit risk, especially in grading the low and high credit risk �rms. however, further research is needed in the future. more data is needed to restrict the study’s scope according to the �rms’ sectors and other macroeconomic factors. an adjustment can be made to the weighted scoring model’s criteria and scores to follow speci�c business requirements. the way scores were assigned to each level of credit risk also can be improved according to countries’ economic environment. 5. acknowledgement the authors thank to universiti teknologi mara (uitm), cawangan negeri sembilan, kampus seremban 3 for providing research facilities and �nancial support. references abdou, h. a. and j. pointon (2011). credit scoring, statistical techniques and evaluation criteria: a review of the literature. intelligent systems in accounting, finance and management, 18(2-3); 59–88 altman, e. i. 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116–121 zorn, a., m. esteves, i. baur, and m. lips (2018). financial ratios as indicators of economic sustainability: a quantitative analysis for swiss dairy farms. journal of sustainability, 10(8); 2942 © 2021 the authors. page 112 of 112 introduction methodology data setting estimating the default probabilities of firms using the kmv-merton model calculating the weightage of default probability and financial ratios calculating the credit score of firms determining the credit rating of the firms results and discussion the default probabilities and financial ratios credit score and credit rating conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper the impact of climate change on cooling energy demand in indonesia based on representative concentration pathways (rcp) scenarios desak putu okta veanti1*, rista hernandi virgianto1, i gusti ayu putu putri astiduari2 1department of climatology, school of meteorology climatology and geophysics, jakarta, 15221, indonesia 2department of meteorology, school of meteorology climatology and geophysics, jakarta, 15221, indonesia *corresponding author: okta.veanti@stmkg.ac.id abstract air conditioning system in a building is necessary to maintain air temperature at a certain comfort level, especially in tropical countries such as indonesia. global warming was believed to accelerate the increase in energy consumption for air conditioning as a consequence of rising surface temperatures. this study aims to quantify the changes in energy consumption used for air conditioning systems based on cooling degree days (cdd) that is calculated from the daily average temperature in indonesia based on rcp4.5 and rcp8.5 scenarios. projections for the future scenarios is compared with the energy consumptions in 2010. the results showedthatenergyconsumptions increaseupto10kwh/m2 year in2030forbothscenarios. in2050rcp4.5showsslightlyhigher ew than rcp8.5 in some regions. however, in 2100, rcp8.5 shows significantly higher energy consumption for air conditioning system. the eastern part of middle kalimantan, south kalimantan, southern part of east kalimantan, northern east java, northern part of lampung, south sumatera, and southern part of papua shows the highest changes (51 to 68 kwh/m2 year) keywords air conditioning, cooling degree day, global warming, surface temperature, climate scenario received: 28 july 2021, accepted: 27 october 2021 https://doi.org/10.26554/sti.2022.7.1.9-16 1. introduction a comfortable temperature for housing is one of the main human needs. as time goes on, there is an increase in the standards of satisfaction followed by an increase in the use of heating and cooling device. as the increase in gdp, more people in indonesia demand more comfortable temperature for their housing. james (2008) states that the main use of energy in a building for heating, cooling, and ventilating contributing a total 43% of the building energy demand. the energy demand for air conditioning system is necessary to maintain a room in comfortable temperature. since indonesia is located in tropical area, air cooling systems are often used in housing especially during warm and sunny days. the demand from o�ce buildings is even higher because they use the air-cooling systems more than household needs in daily basis. according to kementerian energi dan sumber daya mineral (2018), the requirement of electrical energy has reached 1.02 gwh/capita in 2017 or 5.9% higher compared to previous year. from the total users of electrical energy, household group is the largest group of users who contribute in the use of 91.88% of the total electric energy. based on the explanation from the executive director of the international energy agency (iea), fatih birol, world electricity use will be even higher, which is triggered by the use of air conditioning. from this explanation, we are interested in the use of air conditioning in indonesia and the amount of energy this country consumes each year. the next issue related to energy for cooling system is climate change. temperature on land and sea show an increase of around 0.65°c to 1.06°c between 1880-2012, and it is estimated that greenhouse gases will cause sustainable heating with a temperature increase of 0.3°c to 4.8°c from 2081-2100 (stocker, 2014; intergoverment panel climate change, 2013). warmer weather means the demand for cooling energy will increase since the energy consumption and temperature is closely related (national bureau of statistics of china, 2013). the relationship between temperature and cooling energy demand can be explained by a simple concept, cooling degree days (cdd). cdd is a basic quantity for estimating energy consumption of building for cooling based on the air temperature of the environment around the building or houses (assawamartbunlue, 2013). this concept was developed by thom (1952); thom (1954) it is easy to use and quite practical in calculating the energy needed for cooling. the concept https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.9-16&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.9-16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 is already widely used in many research (thevenard , 2011; siyak , 2009; atalla et al., 2018; spinoni et al., 2018). one example is the research conducted by spinoni et al. (2018) which use cdd and hdd concept to analyses its change from 1981 to 2100. it was applied to euro-cordex data and able to explain the trend and its climate conditions. next is the research conducted in libya to calculate the annual heating and cooling energy in requirements for residential building (bodalal et al., 2017). in this study, the concept will be applied on coordinated regional climate downscaling experiment (cordex) for south east asia region (cordex-sea) (tangang et al., 2015). the data provide us with high resolution climate change scenario, therefore it would improve the quality of research related to climate change. the application of cordex-sea dataset on research varied widely. it was used in studying the change in rainfall and its extreme (tangang et al. , 2020; ngo-duc et al., 2017). the other research from nguyen-thuy et al. (2021) used cordex-sea dataset to detect time of emergence of climate signal. the main goal in this paper is to apply the concept of cdd to calculate the energy demand based on representative concentration pathways (rcp) scenarios in indonesia and to �nd out the change in cdd and energy demand in the near future (2050) and far future (2100). 2. experimental section 2.1 research area and datasets the research area in this study is limited to indonesia area in the coordinates of 88°e – 144°e and 10°n – 14°s. part of malaysia which is located in kalimantan island and brunei darussalam is included in study area to see the whole picture of kalimantan island. without those, the results might be misleading because we cannot see the overall topography of the island. the research area is located in tropics, consists of more than 13,000 islands with 5 biggest islands which are sumatera, java, kalimantan, sulawesi, and papua. we should note that some islands are too small to be shown on the map. data used is dataset resulted from southeast asia regional climate downscaling (seaclid) which is also known as coordinated regional climate downscaling experiment for south east region (cordex-sea) (tangang et al., 2015). data used is daily surface temperature and consists of historical from 1951-2005, rcp4.5 and rcp8.5 data from 2006-2100. before using the data, we compare the data with observational data from pondok betung climatological station, located at 106.76°e and 6.25°s. the length of observational data is from 1979 until today. however, because we only compare historical data, we only use the data from 1979-2005. figure 1a shows the time series of monthly temperature from observational data and cordex-sea historical data. it is shown that cordex-sea has similar monthly temperature to observational data. the seasonal cycle is also can be explained by cordex-sea. however, in the period before 1992, cordex-sea tend to be overestimate to the monthly temperature, while in the period after 1992, it is the other way figure 1. (a) the scatter plot of observational data and cordex-sea data from 1979-2005, (b) time series monthly observational data and cordex-sea data from 1979-2005 around. this is because cordex-sea underestimate the real trend of temperature in pondok betung climatological station, jakarta. the relationship between monthly temperature data from observation and cordex-sea can be seen in figure 1b the scatter plot shows that cordex-sea explained 27.9% of observational data. the correlation coe�cient between the two dataset is 0.53 with p-value = 0. it means cordex-sea data has signi�cant positive relationship with observational data. mean absolute error and root mean square error was calculated, resulting the value of 0.53 and 0.66 respectively. therefore, temperature from cordex-sea dataset is good enough to represent the real condition. 2.2 methods in this study, cdd concept is applied to cordex-sea data to �nd out how much the energy needed to keep a space in its most comfortable temperature. cdd is calculated based on rehman et al. (2011) calculation. it is results from subtracting the daily averaged near surface temperature (td) with the base temperature (tb). in this study, daily 2m temperature data from cordex-sea is used to represent averaged near surface temperature (td). base temperature is the temperature in which a space no longer needs cooling. it is simply the tem© 2022 the authors. page 10 of 16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 perature which is wanted or the most comfortable temperature people want to keep. if the temperature of environment is higher than the base temperature, it means some amount of energy will be needed to cool the space. the higher the gap between environmental temperature and the base temperature, the more energy will be needed. most studies use 18°c (65°f) for the tb such as study from shanmugapriya et al. (2011) that researched the cdd for tiruchirappalli in india, and wibig (2003) about hdd and cdd variability in lodz of poland in the period 1931-2000. however, all those studies are done in the extratropical regions. in tropics, people already get used to warmer temperature, therefore it does make sense that indonesian will demand higher tb. hence, we found other standard for tb which is the regulation of the ministry of energy and mineral resources of republic indonesia number 13 of 2012 concerning the saving of electricity use. in chapter ii concerning the implementation of electricity saving, article 4 paragraph 6 which regulates the temperature of air conditioning use. based on the decree, 22°c – 24°c is the base temperature and, in this study, we use 24°c as the base temperature (intergoverment panel climate change, 2014a; intergoverment panel climate change, 2014b). the energy consumption is calculated based on cooling degree days (cdd) that calculated by subtracting the td with tb mentioned (buyunakalaca et al., 2001; rehman et al., 2011). cdd = td −tb (1) equation 1 is used to calculate the value of a daily cdd and then accumulated the value for a certain period. we calculate the seasonal and annual cdd values explained by equation 2 (rehman et al., 2011). acdd = n∑ i=1 cddi { td > tb, then cdd = td −tb if not cdd = 0 (2) with: acdd = accumulated cooling degree days, cdd = cooling degree days, td = daily averaged near-surface temperature, tb = base temperature, n = number of days in certain period. the total energy consumption for air cooling system (ew) is calculated by following equation (bodalal et al., 2017) ew = qw cop (3) with: qw = heat transmission that penetrates the surface of building (kwh/m2), cop= coe�cient of air cooling system performance. heat transmission that penetrates the building surface can be calculated using the following equation (bodalal et al., 2017) qw = 0.024xuoxcdd (4) uo = 1 rwt (5) with: uo = heat transfer coe�cient without insulation (w/m2°c), cdd = cooling degree-days (°c), rwt= thermal resistance of the wall (m2°c/w) uo is used because most buildings in indonesia is without insulation, without the addition of insulation, the radiation between cdd and energy demand (ew) is linear where to cool 1°c cdd, 0.272727 kwh energy is needed. rwt is the thermal resistance of the wall that is 0.44 m2 °c/w so that the uo value or the heat transfer coe�cient without insulation is 2.2727 w/m2 °c. cop is the coe�cient of performance of the ac cooling system and is assumed to be equal as 2 (bodalal et al., 2017). to study the in�uence of climate change on energy demand for cooling, we use two rcp scenarios. rcp is the latest generation of scenarios that provide input to climate models. both scenarios are available in cordex-sea data. rcp4.5 (intermediate emission) is a scenario which stabilizes radiative forcing at 4.5 w/m2 in the year 2100 without ever exceeding that value (thomson et al., 2011). rcp8.5 (high emission) is consistent with a future with no policy changes to reduce emission is characterized by increasing greenhouse gas emission that leads to high greenhouse gas concetration overtime. increase of global mean surface temperatures for 2081–2100 relative to 1986–2005 is projected to likely be in the ranges derived from the concentration driven cmip5 model simulations, that is 1.1°c to 2.6°c for rcp4.5 and 2.6°c to 4.8°c for rcp8.5. 3. results and discussion 3.1 present condition, spatial analysis of cdd and ew from 1951-2005 after applying cdd concept and bodalal et al. (2017) method on cordex-sea historical data, maps of energy demand for cooling are derived. it is shown in figure 2a and 2b. figure 2a shows the mean yearly accumulated cdd over indonesia from 1951-2005. it was the result of accumulating cdd for each year then calculating the mean for the period of 1951-2005. note that the quantities will be explained in degree-days. from the map, it is clear that cdd over indonesia is highly related to its topography. the coastal area tends to have higher cdd values while the mountains and highland tend to have lower cdd. other factors such as di�erence in latitude does not show obvious e�ect because indonesia lays on a narrow band of tropical region and its area stretch wider from west to east. coastal area and lowland tend have more than 700°c/year while higher places have cdd less than 700°c/year. some places have very high yearly accumulated cdd (more than 1400°c/year). it is found on small islands such as nias island and siberut island that located in the west of sumatera island, eastern coast of madura and some small islands around © 2022 the authors. page 11 of 16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 figure 2. (a) the cdd average year from 1951-2005, (b) the ew average year from 1951-2005 it, peleng island in the east of sulawesi island and in some spots on maluku islands. this value can be found in the southern coast of kalimantan too. ew shows similar pattern with cdd map because its relationship is linear. lowlands and coastal areas tend to have ew more than 20 kwh/m2 year while higher lands and mountains have ew less than 20 kwh/m2 year. this means people who live in lowland and coastal area need more energy for cooling. the fact that most population live in the lowland and coastal regions make it important to consider that most people need high amount of energy for cooling their houses and buildings. the value of cdd might be in�uenced by urban heat e�ect too, similar to study in bandung (arifwidodo et al., 2019; arifwidodo et al., 2021) 3.2 future condition, time series analysis of cdd and ew after calculation of cdd and ew, two grid point is picked to see the examples of how the time series of cdd and ew look like. one grid point represents the coastal area and lowland (106.69°e and 6.15°s, in tangerang selatan-tangsel). the other grid point represents highland (106.91°e and 6.82°s, close to pangrango mountain-pangrango). time series of cdd and ew of the chosen grid points are shown in figure 3a and 3b . cdd graph from 1951-2100 is shown on figure 3a, pangrango shows pronounced lower cdd comparing to tangsel grid. however, both grids have similar line shape. baseline data from 1951-2005 does not show pronounced trend. the cdd at tangsel is around 1,000 degree-days in this time pefigure 3. (a) the time series of cdd from 1951-2100; (b) the time series of ew from 1951-2100. riod while the cdd at pangrango is only around 20 degreedays. the trend in the next period (2006-2100) is shown in two scenarios, rcp4.5 and rcp8.5. rcp4.5 time series shows rapid increasing trend from 2005-2050 then the trend is somehow no longer as rapid as the previous trend in the period 2050-2100. the graph shown by rcp8.5 scenario is di�erent. it shows similar rapid positive trend but does not stop in 2050. in the other hand, the positive trend is persistently rapid for the period 2050-2100. therefore, in the mid-century both rcp4.5 and rcp8.5 show similar cdd values while in the end of century those scenarios show di�erent values. in tangsel, rcp4.5 shows cdd in 2100 around 1,900 degree-days and rcp8.5 around 2,700 degree-days, while in pangrango, rcp4.5 shows cdd around 600 degree-days and rcp8.5 around 1,700 degree-days. figure 3b shows the linear relationship between ew and cdd in both sample grids. the cooling energy needed in tangsel shows no signi�cant trend during baseline period as well as in pangrango with the di�erence in ew is approximately 30 kwh/m2 year. in both sample grids, both of rcp4.5 and rcp8.5 show signi�cant increase in ew from 2005 to 2050. moreover, after 2050, rcp4.5 shows only slight increase and rcp8.5 keep showing rapid increase in ew in both grids. in pangrango, rcp4.5 simulation gives ew around 30 kwh/m2 year in 2100, while rcp8.5 gives around 18 kwh/m2 year. meanwhile, in tangsel, rcp4.5 projects ew around 75 kwh/m2 year in 2100, while rcp8.5 around 50 kwh/m2 year. © 2022 the authors. page 12 of 16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 figure 4. the cdd trends for 2006-2100 period based on: (a) rcp4.5 and (b) rcp8.5. 3.3 cdd trends based on rcp4.5 and 8.5 simulation as shown in figure 4a, the cdd trends for 2006-2010 period based on rcp4.5 scenario increase between 10 to 15 degree-days/year in south-eastern sumatra, south kalimantan, north-eastern java, west papua and south papua. meanwhile, lower increase in trends shown mostly in mountains area in the middle part of sumatra, kalimantan, sulawesi, papua and in southern java. figure 4b shows higher increase in cdd trends based on rcp8.5 than rcp4.5. highest positive trends value approximately from 20 to 25 degree-days/year that occurred in most parts of the islands in indonesia except the middle part that shows lower increase in cdd. same as shown in figure 4a, the highland and mountains areas dominate the area of lowest increase in cdd trends based on rcp8.5 with the value from 0 to 5 degree-days/year. largest area with the highest positive increase in cdd is kalimantan, while the largest area with the lowest one is middle part of papua. 3.4 ew trends based on rcp4.5 and 8.5 simulations similar trends pattern as in cdd, also shown in figure 5a, the ew trends for 2006-2010 period based on rcp4.5 scenario have the highest positive value in south-eastern sumatra, south kalimantan, north-eastern java, west papua and south papua. meanwhile, lower increase in trends shown mostly in mountains area in the middle part of sumatra, kalimantan, sulawesi, papua and in southern java with more than 0.5 kwh/m2 per year. figure 5b shows higher increase in ew trends based on rcp8.5 than rcp4.5. highest positive trends mostly occurred in low altitude area of the islands, while the highland and mounfigure 5. the ew trends for 2006-2100 period based on: (a) rcp4.5 and (b) rcp8.5. tains areas in central parts of major islands still dominate the area of lowest increase in ew. 3.5 the di�erence of energy demand for air conditioning system (ew) in 2050 and 2100 to mean energy demand (ew) 1950-2005 for technical use, it is important to know the change of ew in mid-century (2050) and end-century (2100). therefore, the change between those periods is calculated. the calculation is simply estimating the di�erence of ew in 2050 to mean ew period 1950-2005 for the change in mid-century and estimating the di�erence of ew in 2100 to mean ew period 1950-2005 for the change in end-century. the results for the entire area of indonesia are mapped in figure 6. as shown on the map, the changes in 2050 and 2100 are positive. in 2050, both rcp4.5 and rcp8.5 shows similar changes with slightly di�erent pattern. in 2100, the changes are even higher especially for rcp8.5 scenario. while in 2050 both scenarios show slightly similar pattern, in 2100 the difference between two scenarios are obvious. rcp8.5 scenario clearly shows higher ew comparing to rcp4.5 scenario. the hotspots of changes in ew are also clearer for rcp8.5 scenario. this development is on the line with the data example at pondok betung climatological station, jakarta. both scenarios show similar trend till mid-century then rcp4.5 scenario shows weak positive trend while rcp8.5 scenario keeps its pace. from rcp4.5 scenario, in 2050, the changes in ew over © 2022 the authors. page 13 of 16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 figure 6. the di�erence of energy demand for air conditioning system (ew) in 2050 and 2100 to mean energy demand (ew) 1950-2005 indonesia are 17 kwh/m 2 year or less. some regions show higher changes, around 17 to 34 kwh/m2 year such as southeastern part of sumatera, west borneo, mid borneo, south borneo, southern part of east borneo, north coastal of java, southern part of south east sulawesi, some small islands close to papua, southern part of papua, and some spots on northern part of papua. those areas are also the hotspots of cdd trends for rcp4.5 scenario. in 2100, the changes in eware higher. the changes in ew in most areas of indonesia are 17 to 34 kwh/m2 year. only some small areas have changes less than 17 kwh/m2 year such as mountains barisan, southern part of java, bali and lombok, northern part of borneo, middle part of sulawesi, north-eastern part of papua, and mountains jaya wijaya. most of those areas are mountains and high lands. based on the rcp8.5 scenario, in 2050, the change of ew in most of indonesia area is also less than 17 kwh/m2 year. however, the hotspots are di�erent. rcp8.5 scenario shows less hotspots which changes are 17 to 34 kwh/m2 year such as lampung, south sumatera, southern part of borneo, some spots on east and north borneo, and some small islands close to papua. in 2100, the change of ew for rcp8.5 scenario more or less double the change of ew for rcp4.5 scenario. most indonesia areas changes 34 to 51 kwh/m2 year by 2100. the area in mountains and highlands changes less than 34 kwh/m2 year such as mountains barisan, mountains jaya wijaya, north-eastern part of papua, in the middle of sulawesi, some northern part of borneo and southern part of west java. some areas are the hotspots for the change in ew, changes more than 51 kwh/m2 year by 2100 which are south-eastern part of sumatera, south-eastern part of borneo, northern part of east java, and southern part of papua. 4. conclusions this study applies cdd concept into cordex-sea data to �nd out the in�uence in climate change to cooling energy demand in indonesia. it is also used to understand more about the change in energy demand in the near future and far future. after studying the conditions in indonesia to derive the relationship between cdd and ew in indonesia, it is found out that the relationship of both is linear. it is due to the fact that most buildings in indonesia have no insulations. this leads to ine�cient use of the energy needed for cooling; hence, more energy is needed to cool a space. this condition can be improved by applying insolation to buildings, however, the cost e�ciency to build this kind of wall is still need to be studied. from the mean cdd and ew in indonesia (figure 2a and figure 2b), it can be seen that cooling energy demand in indonesia is highly related to topography. coastal area and small islands tend to have the highest cooling energy demand while mountains area tend to have lowest energy demand. in fact, the most populated major cities in indonesia are at or close to coastal area, for example: jakarta, denpasar, surabaya, and makassar. this means most people live in the area where the energy demand for cooling is high. with the growing use in air conditioning system, it is estimated the total use of cooling energy of the country will also grow, especially in big cities. in tropics, warming is a substantial part which can increase the amount of energy needed for cooling. the application of two scenarios from cordex-sea shows positive trends in both cdd and ew (figure 4a-b, figure 5a-b). from these re© 2022 the authors. page 14 of 16 veanti et. al. science and technology indonesia, 7 (2022) 9-16 sults, it is safe to say that climate change will cause and increase in energy demand for cooling in indonesia. however, rcp4.5 clearly shows lower trend comparing to rcp8.5. the way we solve the climate change problem will in�uence the amount of energy we need to use in the future. therefore, climate change mitigation strategy should be taken seriously. in 2050 rcp4.5 shows slightly higher ew than rcp8.5 in some regions. however, in 2100, rcp8.5 shows signi�cantly higher energy consumption for air conditioning system. the eastern part of middle kalimantan, south kalimantan, southern part of east kalimantan, northern east java, northern part of lampung, south sumatera, and southern part of papua shows the highest changes (51 to 68 kwh/m2 year) 5. acknowledgement we thank to the head of agency, meteorology climatology and geophysics of republic of indonesia (bmkg) for the cordex-sea datasets. further thanks to the board member of school for meteorology, climatology and geophysics (stmkg) for their support in this research. references arifwidodo, s. d., chandrasiri, o., abdulharis, r, and kubota, t. 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(2003). heating degree days and cooling degree days variability in lodz in the period 1931-2000. in fifth international conference on urbun climate. lodz, poland. 471– 474 © 2022 the authors. page 16 of 16 introduction experimental section research area and datasets methods results and discussion present condition, spatial analysis of cdd and ew from 1951-2005 future condition, time series analysis of cdd and ew cdd trends based on rcp4.5 and 8.5 simulation ew trends based on rcp4.5 and 8.5 simulations the difference of energy demand for air conditioning system (ew) in 2050 and 2100 to mean energy demand (ew) 1950-2005 conclusions acknowledgement microsoft word preface.docx science & technology indonesia preface 1 preface volume 2 number 3 july 2017 science and technology indonesia issue volume 2 no 3 july 2017 is recently online available. please cite the article freely. the topic in this field is also chemistry. science and technology indonesia is consistent for five articles published until this issue. we hope the article can be published more to enlarge the scope and scientist reader. we also invite all researchers in the world to submit article to science and technology. the article will be reviewed by corresponding scientist according to the field of article. for that aim, please see our guideline for author, which has available in the homepage of journal. please feel free to contact us for further information. editorial board. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 2, april 2019 author index 1. aldes lesbani 2. bimo brata adhitya 3. citra indriyati 4. febrinasti alia 5. ineke febrina anggraini 6. m.baitullah al amin 7. muhammad faizal 8. muhammad said 9. neza rahayu palapa 10. puteri kusuma wardhani 11. p. e. kristanto 12. risfidian mohadi 13. sri haryati 14. suharsono 15. tarmizi taher 16. tiara armita 17. wamiliana 18. yosi saria 1 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 3, july 2021 research paper modification of cu/cr layered double hydroxide by keggin type polyoxometalate as adsorbent of malachite green from aqueous solution neza rahayu palapa1, tarmizi taher2, alfan wijaya3, aldes lesbani1,3* 1graduate school of faculty of mathematics and natural sciences, sriwijaya university, palembang, south sumatra, indonesia2department of environmental engineering, institut teknologi sumatera, lampung selatan, indonesia3research center of inorganic materials and complexes, faculty of mathematics and natural sciences, sriwijaya university, indralaya, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstractmodification of cu/cr layered double hydroxides (ldhs) has been conducted by intercalation using keggin type polyoxometalate[𝛼-siw12o40]4− to form cucr-[𝛼-siw12o40]. the materials were analyzed by xrd, ftir, and surface area analyses. furthermore,materialswereusedasselectivityadsorbentsofcationicdyessuchasmalachitegreen, rhodamine-bandmethyleneblue. themala-chite green is more selective than others from an aqueous solution. the adsorption of malachite green showed that the adsorptioncapacity of cucr-[𝛼-siw12o40] was higher than pristine ldhs. the adsorption process was followed pseudo second order kineticmodel and langmuir isotherm adsorption. the qmax value of cucr-[𝛼-siw12o40] reached 55.322 mg/g at 323 k after 100 min-utes adsorption time. thermodynamic parameters such as δg, δh and δs confirm that the adsorption process was endothermic,spontaneous, and more favorable at high temperatures. the intercalated material was higher structural stability toward reusabilityadsorbent than pristine ldhs. keywordsmalachite green, polyoxometalate, intercalation, layered double hydroxides, adsorption received: 7 april 2021, accepted: 20 july 2021 https://doi.org/10.26554/sti.2021.6.3.209-217 1. introduction the existence of chemical substances in the environment is a vital topic to discuss until this decade due to toxic properties and caused pollution in the land and aquatic systems. these chemicals including heavy metals, organic pollutants, and also dyes. dyes substances were produced from industrial activities including textile, plastic, printing, leather, and so on (abdelkader et al., 2011). these dyes are usually released to the environment directly without gradually further treatment thus can impact humans, ora, and fauna (dahri et al., 2014). the removal of dyes from wastewater is an important way to minimize the serious eect. various physicochemical and biological methods have been applied to remove dyes from wastewater such as adsorption, coagulation, ltration, precipitation, light decomposition, and also using bacterial process (dai et al., 2018; gholami et al., 2020; srinivasan and sadasivam, 2018; xu et al., 2018b). among these methods, adsorption is a suitable method for the removal of dyes from wastewater due to fast process, simple way, easy procedure, and also no contamination eect before and after the process (nazir et al., 2020; jarrah et al., 2020; naseeruteen et al., 2018). the eectiveness of the adsorption process is depending on the ability of the adsorbent. various kinds of adsorbents have been used for removing dyes from wastewater such as zeolites (oliveira et al., 2019), activated carbon (mall et al., 2005), natural layer structure materials such as bentonite and kaolinite (bulut et al., 2008), and also synthetic materials such as layered double hydroxides (das et al., 2018; lesbani et al., 2020c; parida and mohapatra, 2012). layered double hydroxide (ldhs) is a class of synthetic layer materials with positively charged and consists of interlayer anions (lesbani et al., 2020a). interlayer anions can be exchanged with various anions to increase interlayer distance or gallery of ldhs. the general formula of ldhs is [m2+1−xm3+x (oh)2]x+(an−)x/n].nh2o, where m is divalent and trivalent metal ions and an− is interlayer anions with valence n (palapa et al., 2020b). the interlayerof ldhs contains anions such as nitrate, chloride, sulfate, and other ions due to synthetic conditions (doungmo et al., 2016; lesbani et al., 2020b; parida and mohapatra, 2012). the unique properties of interlayer ldhs is the ion exchange properties. interlayer anions can be exchanged with other anions to obtain a high interlayer distance of ldhs (ma et al., 2013; oktriyanti et al., https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.3.209-217&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.3.209-217 neza et. al. science and technology indonesia, 6 (2021) 209-217 figure 1. chemical structure of malachite green 2020; zhu et al., 2017). these novel properties are useful for various applications of ldhs such as adsorbents (shan et al., 2015), catalysts (sun et al., 2019), biomedical materials (liao and chen, 2016), and other industrial applications (zubair et al., 2017). adsorption of dyes using ldhs has been tested for various dyes such as methylene blue (lesbani et al., 2020a), indigo carmine (starukh and levytska, 2019), methyl orange (elmoubarki et al., 2017), and malachite green (lesbani et al., 2020c). that dyes are classied as cationic and anionic dyes depending on the structures of dyes. one of the toxic dyes is malachite green. this dye is classied as a cationic dye with the chemical structure shown in figure 1. ldhs are almost treated with physical or chemical techniques before being applied as an adsorbent in the adsorption process (silaen, 2020). this step aims to increase the surface area and interlayer distance of ldhs for active sites of adsorption. on the other hand, intercalation using a large anion is eective to increase the interlayer distance of ldhs and surface area properties (palapa et al., 2020a). large anions such as polyoxometalate ions are frequently used as an anion for the intercalation process onto ldhs (legagneux et al., 2009). then materials after intercalation were applied as adsorbents of dyes (lesbani et al., 2020b). polyoxometalates are metal-oxygen clustercompoundswithvarious structures suchaskeggin, dawson, anderson, and also lacunary form (carriazo et al., 2007; yang et al., 2012; yun and pinnavaia, 1996). among these structures, keggin is well known used not only as a catalyst (lesbani et al., 2015) and building blocks (long et al., 2010) but also for intercalation anion of ldhs (bi et al., 2011). according to nijs et al. (1999) mgal ldh was intercalated using [h2w12o40]6− to form pillared compounds with various mass ratios of polyoxometalate. the others type of polyoxometalate k3[𝛼-pw12o40] and k4[𝛼-siw12o40] have been carried out as intercalants on znal and caal ldh as reported by lesbani et al. (2018); taher et al. (2019). according to previous research, the ldh intercalated using polyoxometalate has been reported to enhance adsorptive capacity. xu et al. (2018a) reported that znalfe-polyoxometalate was applied as an adsorbent to remove methylene blue in an aqueous solution and obtained an adsorptive capacity is 67.47 mg/g. bi et al. (2011), also reported that znal-[pw10mo2o40]5− was conducted to remove cationic dyes. the adsorption capacity of znal-[pw10mo2o40]5− slightly enhanced compared znal pristine (from 12 mg/g to 30 mg/g). in this research, polyoxometalate keggin ion [𝛼-siw12 o40]4− was used as an intercalant of copper-chromium (cucr) ldhs to form cucr-[𝛼-siw12o40] ldhs. materials were characterized using x-ray diraction, ftir spectroscopy, and nitrogen adsorption-desorption isotherm analysis. furthermore, intercalated and pristine ldhs were applied as adsorbents of malachite green from an aqueous solution. before the adsorption process was conducted, the selectivity adsorption has been examined using a mixing solution of malachite green (mg), rhodamine-b (rh-b) and methylene blue (mb). adsorption was studied by a batch system using a small reactor equipped with stirring and temperature control. based on the above explanation, the objective of this study is to determine the kinetic parameter, isotherm adsorption and thermodynamic studies of mg on intercalated and pristine cucr ldhs. structural stability of cucr-[𝛼-siw12o40] toward reusability adsorbent was also investigated systematically. 2. experimental section 2.1 chemical and instrumentation thechemicalswerepurchasedfrommerckr suchascu(no3)2 .6h2o, cr(no3)3.9h2o, naoh, na2co3, na2wo4, kcl, na2sio3 and hcl. water was supplied from research center of inorganic materials and complexes, fmipa universitas sriwijaya through ltration using puriter water ion exchange system under several times cycling process. the materials were characterized by xrd rigaku miniex-6000. sample was grounded with mortar and analyzed using xrd at diraction 5-60◦ with scan speed 1◦/min. analysis of functional group was performed using ftir shimadzu prestige-21. sample was mixed with kbr and was vacuumed to form kbr pellet. sample was analyzed in the wavenumber 400-4000 cm−1. analysis of nitrogen adsorption-desorption was conducted using micrometric asap quantachrome apparatus. sample was degassed several times prior analysis using liquid n2 to remove guests. analysis of malachite green was conducted using uv-visible spectrophotometer bio-base bk-uv 1800 pc. malachite green was analyzed at 617 nm. 2.2 preparation of cucr ldhs preparation of cucr ldhs was carried out by precipitation method as follows. as much as 7.5 m solution of cu(no3)2. 6h2o 0.05 l was added into 2.5 m solution of cr(no3)3. 9h2o 0.05 l with vigorous stirring. the mixing solution was stirred for an hour then 4m solution of naoh 0.025 l was added and the solution was adjusted to ph 10 by the addition of naoh 4m. the mixing solution was kept for 16 hours to form a gel. the gel was ltered and washed with water several times and dried at 100◦c for 24 hours. © 2021 the authors. page 210 of 217 neza et. al. science and technology indonesia, 6 (2021) 209-217 2.3 preparation of cucr-[𝛼-siw12o40] ldhs the intercalation of cucr ldhs with [𝛼-siw12o40]4− was conducted by ion-exchange technique. ion [𝛼-siw12o40]4− was prepared by previously reported literature (lesbani et al., 2015). as much as 2 g of cucr ldh was dissolved into 0.05 l of water. polyoxometalate k4[𝛼-siw12o40] (15 g) was dissolved with 0.05 l water. the solution of cucr ldhs was mixed with polyoxometalate solution with mild stirring under nitrogen ow for 24 hours to form a suspension. the suspension was ltered and washed several times usingwaterand dried at room temperature. 2.4 adsorption study and reusability adsorbent before the adsorption process was conducted, the selectivity adsorption has been tested. this study aimed to show the materials have good selectivity for specic cationic dyes. the mixture of cationic dyes such as mg, rh-b and mb was prepared with 10 ml and the initial concentration of each dye is 15 mg/l. the adsorption of mg was performed by batch system equipped with a stirring bar and temperature system control. the adsorption process was studied by variation of adsorption times, temperatures, and mg concentrations. the mass of adsorbent was carried out using 25 mg. the volume of adsorbate was 25 ml. variation of adsorption time was studied in the range of 5-210 minutes. variation of initial concentration of mgwas studied at 10, 25, 50 and 75 mg/l. variation of adsorption temperature was studied at 303, 313, 318, and 323 k. the adsorption parameter was obtained through calculation by kinetic model, isotherm adsorption and thermodynamic parameters. concentration of mg after adsorption was analyzed by uv-visible spectrophotometer at 617 nm. the kinetic model was calculated using pseudo rst order (p-fo) and pseudo second (p-so) kinetic models by equation below (doğan and alkan, 2003): log (qe-qt) = log qe − ( k1 2.303 ) t (1) t qt = 1 k2qe2 + 1 qe t (2) where, qe is adsorption capacity at equilibrium (mg/g); qt is adsorption capacity at t (mg/g); t is adsorption time (minute); k1 is adsorption kinetic rate at p-fo (/minute) and k2 is adsorption kinetic rate at p-so (g/mg.min). isotherm adsorption studywas conducted bylangmuirand freundlich equation as written as (obike et al., 2018): 1 qe = 1 qmax + 1 qmaxb . 1 ce (3) ln qe = ln kf + ( 1 n ) ln ce (4) figure 2. xrd powder patterns of cucr (a) and cucr[𝛼-siw12o40] ldhs where, qmax is the maximum adsorption capacity conducted in the monolayer (mg/g); b is the langmuir adsorption equilibrium constant (1/mg); ce is the equilibrium concentration (mg/l); and kf is freundlich constant. the reusability of adsorbent was conducted to investigate the structural stability of adsorbent toward adsorption. desorption of malachite green was performed using ultrasonic system and adsorbent was reuse for the next adsorption process. the dried adsorbent was reused for three cycles with a similar procedure. 3. results and discussion materials of cucr and cucr-[𝛼-siw12o40] were characterized using xrd diraction as shown in figure 2. the characteristic diraction of cucr ldhs appeared at 9.89◦ (003), 27.32◦ (006), 36.10◦ (015), 48.98◦ (018), 60.60◦ (110), and 62.55◦ (116) (palapa et al., 2020b). the diraction peak at 9.89◦ with reection 003 denote the interlayer space of ldhs. material cucr-[𝛼-siw12o40] showed similar diraction as pristine ldhs, but the interlayer of cucr-[𝛼-siw12o40] was increased from 7.55 å to 10.27 å. however, the intercalation of [𝛼-siw12o40] onto cucr ldhs can increase basal spacing up to 2.72 å. the ftir spectra of cucr and cucr-[𝛼-siw12o40] were shown in figure 3. ftir spectrum of cucr ldhs showed the intense vibration at 1381 cm−1 denotes as nitrate bending. the broad vibration was identied at wavenumber 3448 cm−1 due to oh stretching from water molecule. the water-associated vibration also appeared at 1627 cm−1, which was assigned as bending oh vibration (daniel and thomas, 2020). the intercalation of cucr ldhs with [𝛼-siw12o40]4− ion will replace the nitrate as anion on interlayer space. the ftir spectrum after intercalation showed the vibration around 1107 cm−1, which was assigned as the presence of another anion (co) from carbonate. the unique vibration of [𝛼-siw12o40] from cucr-[𝛼-siw12o40] shows at wavenumber below 1000 cm−1 (w=o and si-o). © 2021 the authors. page 211 of 217 neza et. al. science and technology indonesia, 6 (2021) 209-217 figure 3. ftir spectrum of cucr and cucr-[𝛼-siw12o40] ldhs analysis of adsorption-desorption nitrogen on cucr and cucr-[𝛼-siw12o40] is shown in figure 4. the prole of adsorption-desorption nitrogen is categorized as type iv with h3 hysteresis loop for both ldhs. the isotherm pathway indicated the mesopore materials, which were associated with capillary condensation (harizi et al., 2019). the bet calculation was obtained from data in figure 4 as shown in table 1. figure 4. nitrogen adsorption-desorption of cucr and cucr-[𝛼-siw12o40] ldhs the data in table 1. showed the bet analysis of cucr and cucr-[𝛼-siw12o40] ldhs. the increase of the surface area of ldhs after intercalation by [𝛼-siw12o40] was found with the decreases in the pore size. thus, the decreases in pore size indicated the swelling and the covering of interlayer space by macroanion [𝛼-siw12o40]4−. these phenomena are related to the opening of interlayer space, which was conrmed by xrd analysis (ouassif et al., 2020). the surface area of cucr-[𝛼-siw12o40] was increased up to vefold than cucr ldhs. ldhs intercalated by polyoxometalate are potential material as an adsorbent to remove pollutants from wastewater. furthermore, to determine the adsorption ability of cucr-[𝛼siw12o40], the adsorption selectivity of cationic dyes (mg, figure 5. wavelength scan of selectivity adsorption by cucr-[𝛼-siw12o40] (a) and cucr (b) ldhs onto mixing mg, rh-b and mb figure 6. eect of adsorption time (a) and kinetic model (b) rh-b and mb) has been studied as shown in figure 5. figure 5(a) showed that cucr-[𝛼-siw12o40] adsorbed mg higher than other cationic dyes. the decrease in absorbance value indicates a decrease in initial concentration. however, the decrease dramatically of initial concentration of mg indicated that the small structure of mg than rh-b and mb (mohadi et al., 2021). figure 5(b) also showed a similar nding that mg more selectivity than others. the nal concentration of mg after 150 min of cucr and cucr-[𝛼-siw12o40] are 8.1 and 5.4 mg/l, respectively. thus, the cucr-[𝛼-siw12o40] was used as an adsorbent to remove mg from the aqueous solution. theadsorptionprocesswascarriedoutbytheeectof adsorption time, theeectofmgconcentrationandadsorption temperature. the eect of adsorption time for mg removal using cucr and cucr-[𝛼-siw12o40] was shown in figure 6. figure 6(a) showed mg was higher adsorbed using cucr[𝛼-siw12o40] than pristine ldhs. this nding assumed that the higher surface area of cucr-[𝛼-siw12o40] after intercalation. the equilibrium amount of mg on cucr-[𝛼-siw12o40] was reached after 100 minutes with mg removal up to 90% from the initial concentration 50 mg/l. the results showed that mg uptake on cucr-[𝛼-siw12o40] were higher twice thancucrldhs. thus, theadsorptionkineticwasdetermined by pseudo kinetic model. figure 6(b) showed the tted of two kinetic models. the calculated parameters were listed in table 2. based on figure 6(b) and table 2, kinetic adsorption of mg on cucr and cucr-[𝛼-siw12o40] were followed ps-o model with coecient correlation >0.963. © 2021 the authors. page 212 of 217 neza et. al. science and technology indonesia, 6 (2021) 209-217 table 1. bet surface area analysis of cucr and cucr-[𝛼-siw12o40] ldhs materials surface area (m2/g) pore size (nm) cucr ldh 4.58 14.39 cucr[𝛼-siw12o40] 26.58 2.023 table 2. kinetic parameter of adsorption on cucr and cucr[𝛼-siw12o40] adsorbent qeexp p-fo p-so (mg/g) qecalc (mg/g) r 2 k1 qecalc (mg/g) r 2 k2 cucr 27.985 23.051 0.948 0.017 31.24 0.977 0.001 cucr[𝛼-siw12o40] 18.354 45.651 0.924 0.023 52.619 0.963 0.0007 figure 7. eect of initial concentration of mg and adsorption the eect of initial concentration and adsorption temperature of mg were presented in figure 7. the amount of mg adsorbed on cucr-[𝛼-siw12o40] was increased by increasing adsorption temperature, which was conducted on a batch adsorption system. the adsorption patterns for both materials have equilibrium after 20 mg/l and higher mg was adsorbed at 323 k. furthermore, the data of initial concentration and adsorption temperature for both materials were calculated using langmuir and freundlich isotherm model to obtain isotherm adsorption. the data in table 3 showed that adsorption of mg by cucr and cucr-[𝛼-siw12o40] follow langmuir isotherm adsorption model rather than freundlich model. the coecient correlation for langmuir isotherm is almost close to one than freundlich isotherm. the qmax for cucr-[𝛼-siw12o40] is higher than pristine ldhs. as expected of increasing surface area properties thus this higher of qmax value is matched results. thus, table 4. showed mg adsorption using several adsorbents. table 4 showed the comparison of malachite green adsorption using several adsorbents. based on results, the adsorption figure 8. reusability of adsorbents capacity of cucr-[𝛼-siw12o40] showed in slightly high as compared other materials assumed that cucr-[𝛼-siw12o40] is eective sorbent to remove malachite green in the aqueous phase. the increasing adsorption capacity of malachite green on cucr-[𝛼-siw12o40] is equal with increasing of interlayer space after intercalation, thus the adsorption process probably occurs mainly on the interlayer of cucr-[𝛼-siw12o40] than the surface of the adsorbent (siregar et al., 2021). the thermodynamic data as shown in table 5 was also calculated from data in figure 7. the thermodynamic parameter results were described for a higher concentration of mg, which was conducted at various temperatures. the δg of adsorption has a negative value means adsorption of mg on cucr and cucr-[𝛼-siw12o40] spontaneously occurred in a batch system. the δh value is less than 40 kj/mol and conrms the adsorption process was endothermic (taher et al., 2017). the value of δs is positive forboth cucrand cucr-[𝛼-siw12o40] formgadsorptionprocess. thus, thisndingindicatedthat the increased degree of freedom of interaction between solid and solution from adsorbate and adsorbent molecules (jaśkaniec et al., 2018; qu et al., 2019). ldhs are unstable materials toward acid thus the ultrasonic system was applied for a reusability test of cucr-[𝛼siw12o40] todesorbmalachitegreenontheadsorbent. figure 8 showed that the adsorption capacity of cucr ldh largely © 2021 the authors. page 213 of 217 neza et. al. science and technology indonesia, 6 (2021) 209-217 table 3. isotherm model parameters of mg adsorption process on cucr and cucr-[𝛼-siw12o40] ldh adsorption adsorption t (k) isotherm constant 303 313 318 323 cucr langmuir qmax 6.016 22.008 23.198 27.585 kl 0.098 0.05 0.176 0.771 r2 0.989 0.973 0.985 0.994 freundlich n 6.518 1.963 3.273 2.826 kf 2.725 2.227 6.555 6.991 r2 0.785 0.9 0.964 0.868 cucr-[𝛼-siw12o40] langmuir qmax 12.127 35.372 46.035 55.322 kl 0.094 0.233 0.297 0.564 r2 0.929 0.998 0.993 0.998 freundlich n 1.972 3.178 3.479 4.048 kf 1.301 6.586 17.676 10.664 r2 0.755 0.855 0.861 0.645 table 4. comparison of malachite green adsorption by several adsorbents adsorbents qmax ref. nial ldh 27.32 (lesbani et al., 2020c) cual ldh 55.22 (palapa et al., 2020a) cual-ldh/bc 470.96 (palapa et al., 2020c) znal ldh 11.1 (palapa et al., 2018) apricot-ac 17.6 (abbas, 2020) leucaena leucocephala 2.389 (lee et al., 2018) nife-ldh/calcined 73.68 (elmoubarki et al., 2017) mw-carbon nanotubes 11.95 (rajabi et al., 2016) cucr ldh 27.585 this work cucr-[𝛼-siw12o40] 55.322 this work table 5. thermodynamic parameter of mg adsorption on cucr and cucr-[𝛼-siw12o40] adsorbents t (k) qe (mg/g) δg (kj/mol) δs (j/mol k) δh (kj/mol) cucr ldh 303 27.357 -1.455 35.792 12.3 313 28.516 -1.097 318 31.807 -0.918 323 32.434 -0.739 cucr-[𝛼-siw12o40] 303 41.421 -0.552 39.7457 11.491 313 44.678 -0.9494 318 45.382 -1.1482 323 46.606 -1.3469 decreased after two cycles adsorption process while cucr-[𝛼siw12o40] relatively stable. the three cycles adsorption process of malachite green showed that adsorption capacity for both adsorbents was decreased. on the other hand, the adsorption capacity of cucr-[𝛼-siw12o40] has almost slightly larger than pristine ldhs. thus, the intercalation process was increased the structural stability of ldhs. 4. conclusions the intercalated cucr ldhs using polyoxometalate keggin anion to form cucr-[𝛼-siw12o40] was successfully prepared and analyzed by xrd, ftir and surface area analysis. the cucr-[𝛼-siw12o40] was applied as an adsorbent of mg. the eect of adsorption time showed the optimum uptake after 100 minutes. material cucr-[𝛼-siw12o40] has a higher adsorption capacity than pristine ldhs due to high surface area © 2021 the authors. page 214 of 217 neza et. al. science and technology indonesia, 6 (2021) 209-217 properties. the kinetic parameters showed that the adsorption process follows ps-o kinetic model. langmuir isotherm was appropriate than freundlich isotherm models for both adsorbents. material cucr-[𝛼-siw12o40] has higherqmax (55.322 mg/g at 323 k) than cucr ldhs (27.585 mg/g at 323 k). thermodynamic parameter results showed the negativity of δg with increasing temperature indicated that the adsorption favorable in high temperature. enthalpy of adsorption showed the value is less than 40 kj/mol and the adsorption process was endothermic. the positive value of δs denotes the concentration of adsorbate has high interaction with adsorbent and aected the entropy to be increased. structural stability of cucr ldhs was slightly increased after the intercalation process. 5. acknowledgement we thank ministry of national education and culture, republik indonesia for nancial support through hibah disertasidoktor2020-2021fromdirectorategeneralhigher edication (dikti) republic indonesia with primary contract number : 054/e4.1/ak.04.pt/2021 and derivative contract number : 0163.02/un9/sb3.lp2m.pt/2021. we also gratefully acknowledge to research center of inorganic materials and complexes fmipa universitas sriwijaya for instrumental analysis. references abbas, m. 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adsorbent results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 4, october 2018 research paper fabrication of thermoplastic elastomers (tpe) by using emulsion method as an alternative material for vehicle bumper protector nur padmi t1*, sri haryati1, subriyer nasir1 puteri kusuma wardhani2 1department of chemical engineering, faculty of engineering, university of sriwijaya, sumatera selatan, indonesia 2department of civil engineering, faculty of engineering, university of sriwijaya, sumatera selatan, indonesia *corresponding author: nurpadmityastuti19@gmail.com abstract research on fabrication of thermoplastic elastomers (tpe) by using emulsion method as an alternative material for vehicle bumper protector aims to produce of the thermoplastic elastomers by emulsion method with variation of composition ratio of polypropylene grafting and maleic anhydride (pp-g-ma)(ml) : latex (ml) : glycerin, to have strong tensile strength results according to british plastic federation standard 0.5 – 2.4 (n/mm2) standard for bumper material elongation maximum of 22.62%. emulsion method was used as sample preparation which is grafting polypropylene (pp) with maleate anhydride (ma) then continued with pp-g-ma emulsion making and natural rubber latex density. the observation technique of the test is done by ftir pp-g-ma analysis, stability test, tpe visual analysis, tpe surface morphology using scanning electron microscopy (sem) tool and tpe tensile strength test. the results of ftir analysis is that the samples closest to the carbonyl value of c = o with the highest absorption were without glycerine samples 1703.48 cm−1 with the absorption of 94.84% and carbonyl c-o 1219 cm−1 with the absorption of 95.19%. the stability testing of density values reaches the standard of the plastic federation of 0.91 1.30 g/ml, for samples having the highest and stable density values up to the seventh day of observation is a sample of pp-g-ma: latex (75:25) which is 1.059 g/ml. in the sem test on the pp-g-ma sample: latex (75:25) with a average diameter pores size of 1.408 µm and the smallest diameter pore size of 0.728 µm. the highest value of tensile strength occurred in the sample with the comparison of pp-g-ma: latex (75:25) 1,175 n/mm2 and a maximum elongation of 22.62%. keywords polypropylene, latex, emulsion method, thermoplastic elastomers received: 13 august 2018, accepted: 13 october 2018 https://doi.org/10.26554/sti.2018.3.4.151-156 1. introduction indonesia is a developing country which has increasing population that causes increasing population that causes increasing of transportation vehicles as it can ease citizens’ mobility. according to bps (centre of national statistics deprtement) data in 2016, indonesia has 14.580.666 units of car and this number increases every year of 1 million units. the increase of cars makes unavoidable tra�c and accident problems, as 98.9 thousands accident cases has happened. in car accident, the body of car is usually bumped, crushed or broken. it hapens because the body of car is usually bumped, crushed, or broken. it hapens because the body of car is made of plastic material from petrochemical industry. the petrochemical industry is a chemical industry that processes raw material of petroleum, natural gas or coal through the chemical process of physics, which produces a various chemical products of basic/upstream petrochemical product, intermediate petrochemical product or downstream petrochemical. the downstream petrochemical industry is an industry that produces petrochemical products in the form of �nal products or �nished products. petrochemical basic materials—natural gas and their derivatives, i.e. ethane, propane, and butane, as well as crude petroleum derivatives, i.e. naphtha will provide petrochemical products such as ole�ns (alkenes), i.e. ethylene, propylene, and butadiene. the demand for petrochemical materials such as ethylene, propylene is commonly used as raw materials in the manufacture of plastics (thermoplastics). thermoplastic materials combined with natural rubber will produce thermoplastic elastomers type materials. the thermoplastic elastomers is a polymer block having elastic properties at room temperature up to 70 ºc. the elasticity is caused by the nature of the physical crosslinking resulting from the intermolecular conductivity. the bond will be interrupted when the thermoplastic elastomers is heated over a https://doi.org/10.26554/sti.2018.3.4.151-156 nur padmi et. al. science and technology indonesia, 3 (2018) 151-156 certain temperature and re-formed when cooled. the preparation of thermoplastic elastomers can be carried out in both liquid and emulsion phases. according to ismail and suryadiansyah (2002), thermoplastic elastomers (tpe) provides better material utilization than thermosetting materials. the advantages of using tpe are it has simple compounds and rapid preparation; moreover, the byproducts are easily reprocessed and recycled (pongdhorn sae-oui, dkk.2010). polypropylene (pp) is an additional thermoplastic polymer with a large molecular weight distribution (meyer and keurentjes, 2005). according to brydson (1999), there are three types of pp that are atatic (ppi), isotactic (ipp) and syndiotactic (spp). pp has unique properties such as high melt temperature, low density, high chemical resistance, and heat resistance. indonesia is one of the world’s natural rubber producing countries with the production of about 2.7 million tons per year, the world’s synthetic rubber production about 12.941 million tons. the utilization of this natural rubber for nontire materials such as latex products for tpe material making is only about 30% (sondari et al., 2010) so to get the high demand for tpe, indonesia annually imports tpe materials from other countries. tpe imports cause tpe prices to be very expensive. according to bps data, indonesia has imported tpe materials of 68.62 tons in 1994, while the opportunity to make tpe from natural rubber is available (deswita et al., 2006). in the year 2000-2004, there was an average increase of 7.87 kilotons. based on the literature study, this research used latex as elastomers and polypropylene (pp) material because these materials are commercial polymer material, have high chemical resistance and heat resistance, which is expected that the mixture of propylene and natural rubber latex made by emulsion blending method will produce in a homogeneous tpe and strong tensile strength. 2. experimental section 2.1 materials and tools the materials used in this research are granules isotactic polypropylene (pp) for analysis 99,6%, maleic anhydride (ma), xylene for analysis 60%, benzene for analysis 60%, hydrogen peroxide for analysis, glycerin pure, carboxymethylcellulose (cmc), latex 60% natural rubber. equipment used in this research includes: mixer philips 60 rpm, beaker glass 500 ml, erlenmeyer 250 ml, magnetic heated stirrer hms-79, 300 ºc thermometer, spatula with spoon & 30 cm stirrer, analytical balance ohaus 200g, scanning electron microscope jeol 6510la, oven memmert 220 ºc, hydraulic universal material tester 50 kn, ir spectrophotometer. 2.2 procedure 2.2.1 graftingpolypropylene(pp)withmaleateanhydride (ma) make grafting polypropylene with maleate anhydride (ppg-ma) by adding 1 gram maleate anhydride added 90 ml xylene, then add 20 gr polypropylene. heat in an erlenmeyer for 20 minutes at 170 ºc, in order to blend all the ingredients perfectly, so that grafting can occur subsequently dissolved in 1 ml of benzene, and 1 ml of hydrogen peroxide with 10 ml of xylene and added to the mixture �rst, for 10 minutes, benzoyl peroxide serves as an oxidizer. 2.2.2 making pp-g-ma emulsion conducted within the beaker glass, the pp-g-ma emulsion was obtained by mixing the pp-g-ma solution in xylene at a concentration of 30% (v/v) stirring rate ± 200-400 rpm followed by addition of 10%glycerine emulsi�er, 200-400 rpm. 2.2.3 makingpp-g-maemulsionwithnaturalrubbersensitive latex conducted in beaker glass equipped with high-speed stirrer. furthermore, the second mixture of latex is stored for stable emulsion stability. the thermoplastic elastomer emulsion is made by mixing the pp-g-ma emulsion with natural rubber latex (lpka). the result of mixing of pp-g-ma emulsion with lpka in various ratios using 10% glycerine emulsi�er is called a thermoplastic elastomer emulsion. 2.2.4 testing the test was performed by analyzing the physical, chemical, and mechanical properties, on the analysis of physical properties measured density value and pore diameter size on sem equipment, chemical analysis was done by observing the absorption of wavelength of c = o and co in grafting pp-g-ma with using ftir equipment, and mechanical properties of tensile strength measurements measured using a 50 kn hydraulic universal material tester. 3. results and discussion 3.1 fourier transform infrared test result (ftir) the ftir test conducted at the islamic university of indonesia, the speci�cation of the tool used the ftir uatr spectrum two perkin elmer, the ftir is used to place the snapshot on the diamond censor (to re�ect the infrared ray) and then copy data on the computer screen to identify the wave crests from the group c = o and co yield from grafting pp-g-ma. there were 4 test pieces consisting of non-emulsion pp-g-ma without glycerine, pp-g-ma by emulsion method on pp-latex comparison sample 25:75, 50:50, and 75:25. 3.2 density test result the density test is started by measuring the mass the thermoplastic elastomers. the volume of the thermoplastic elastomers is then measured by immersing it to the measuring cylinder �lled with water. the stability of density can be determined by © 2018 the authors. page 152 of 156 nur padmi et. al. science and technology indonesia, 3 (2018) 151-156 figure 1. the peak graph of ftir for sample pp-g-ma : latex (75 : 25) without glycerine for 1703,48 cm−1 adsorbstion functional group c=o and for 1219,95 cm−1 adsorbtion functional group carbonil c-o. figure 2. the peak graph of ftir for sample pp-g-ma emulsion with glycerine sampel pp-g-ma : latex (25 : 75) for 1660,80 cm−1 adsorbstion functional group c=o and for 1219,95 cm−1 adsorbtion functional group carbonil c-o. figure 3. the peak graph of ftir for sample pp-g-ma emulsion with glycerine sampel pp-g-ma : latex (50 : 50) for 1635,96 cm−1 adsorbstion functional group c=o and for 1218,56 cm−1 adsorbtion functional group carbonil c-o. figure 4. the peak graph of ftir for sample pp-g-ma emulsion with glycerine sampel pp-g-ma : latex (50 : 50) for 1663,60 cm−1 adsorbstion functional group c=o and for 1213,96 cm−1 adsorbtion functional group carbonil c-o. © 2018 the authors. page 153 of 156 nur padmi et. al. science and technology indonesia, 3 (2018) 151-156 figure 5. diagram of thermoplastic elastomer density measurement on sample pp-g-ma : latex (75 : 25), the value of density did not change which is stable at 1.059 g/ml figure 6. the average pore diameter of sample thermoplastic elastomers pp-g-ma : latex (75 : 25) without glycerine as emulsi�er is 11.175 µm and the smallest pore on the surface area thermoplastic elastomer 1.275 µm. one-week observation. we observed its density in the �rst day, third day, and seventh day. the density data results are shown on �gure 5. 3.3 thermoplastic elastomers surface morphology the morphological analysis was conducted at jakarta state university department of materials engineering. the observation was done by using jeol 6510la scanning microscopy electronic (sem) with 2000 x magni�cation. figures 6 until 9 are the microstructure analysis by showing the pore size of the thermoplastic elastomer surface. 3.4 the result of mechanical properties of the thermoplastic elastomers testing of mechanical properties with a tensile strength test is conducted at polytechnic of sriwijaya by using hydraulic universal tester 50 kn tensile strength test apparatus. the sample was clamped on the aparatus and then several forces are applied to the sample until it reaches its maximum load limit. data of tensile strength test results can be seen in table 1. figure 7. the average pore diameter of sample thermoplastic elastomers pp-g-ma : latex (75 : 25) with glycerine as emulsi�er is 1.408 µm and the smallest pore on the surface area thermoplastic elastomer 0.728 µm. figure 8. the average pore diameter of sample thermoplastic elastomers pp-g-ma : latex (50 : 50) with glycerine as emulsi�er is 3.596 µm and the smallest pore on the surface area thermoplastic elastomer 0.922 µm. figure 9. the average pore diameter of sample thermoplastic elastomers pp-g-ma : latex (25 : 75) with glycerine as emulsi�er is 1.614µm and the smallest pore on the surface area thermoplastic elastomer 0.971 µm. © 2018 the authors. page 154 of 156 nur padmi et. al. science and technology indonesia, 3 (2018) 151-156 table 1. tensile strength test results on thermoplastic elastomers pp-g-ma and latex by emulsion method methode specimen b (mm) h (mm) area max load tensile maximum (pp-g-ma:latex) (mm2) (n) strength (n/ mm2) elongation (%) unemulsion 75:25 25 6 150 70,7 0.471 17,46(without glycerine) emulsion 75:25 25 6 150 176.3 1.175 22.62 50:50 25 6 150 153.4 1.022 21.04 25:75 25 6 150 138.9 0.926 19.71 3.5 disscusion in this research, fabrication of thermoplastic elastomers with polypropylene raw material was processed by grafting maleate anhydride and emulsion on natural rubber concentrated latex by using glycerin and carboxymethylcellulose (cmc) with comparison of sample of pp-g-ma: latex of 75:25 (3: 1), 50:50 (1: 1) and 25:75 (3: 1). tests conducted on this research include physical, chemical and mechanical analysis. the test follows british standard of plastic federation and standard tensile strength for bumper material. in the physical analysis, the density test was conducted by observing the density for 7 days with �rst, third and seventh day observations, aimed to analyze the emulsion stability of the thermoplastic. the test is carried out manually by measuring the mass of thermoplastic elastomers samples and immersing it in water then the increasing volume is recorded as the volume of the sample. the density data recorded in all three samples has a �xed density of the sample with the ppg-ma ratio: latex (75: 25) of 1.059 g/ml. pp-g-ma particle �lls the matrix space of the �exible latex so that the sample density is stable. this value has also met the density standard value of the thermoplastic elastomers of the british plastic federation of 0.91-1.30 g/ml. physical analysis is also done by analysing the diameter of pores of thermoplastic elastomers. when the diameter of pores is greater, its tensile strength and density are smaller and vice versa. the smaller pores diameter indicates that pp-g-ma particles make the sample more dense and has better tensile strength. the size of the pores can be a�ected by the technique of blending and moulding manually when preparing the thermoplastic elastomers product, the measured pore diameter size is high value with the micrometer (µm) unit where the result data on the average pore size is the smallest in the ratio sample pp-g-ma: latex 75: 25 (3: 1) ie 1.408 µm with the smallest pore diameter size 0.728 µm. the analysis of chemical properties is conducted by using ftir instrument to analyze carbonyl bonds c = o and c-o occurring in grafting method performed on polypropylene and maleic anhydride. from the result data, it is found that wavelength absorption of c = o has met the adsorption standard c = o group of 1600 -1750 cm−1. sample pp-g-ma : latex (75 : 25) without glycerine of polypropylene grafting with pure maleate anhydride before the emulsion treatment successfully has wavelength data of 1703.48 cm−1 with a percentage of 94.84%. the lowest absorption percentage of the wavelength of the c = o group occurs in the comparison of pp-g-ma: latex of 75:25 (3: 1) with the value of 86.48%. in the c-o group, the pp-g-ma : latex (75 : 25) without glycerine sample has a wavelength of 1219.95 cm−1 with an absorption percentage of 95.19%, then the sample which has the lowest absorption percentage in the 75: 25 (3: 1) sample is 85.46%. the di�erence in absorption percentage is due to the in�uence of an emulsion method which adds emulsi�er glycerin and solid particle vibration to polypropylene which causes the absorption intensity at c = o and c-o group to decrease to 8.36%. in the analysis of mechanical properties measured by tensile strength test in units (n/ mm2), various forces are applied to the samples until it reaches its maximum limit. based on the standard british plastic federation and tensile strength testing standards of the tensile strength bumper material in the range of 0.5 to 2.4 (n / mm2), it is found that three thermoplastic elastomers samples made by comparison of pp-g-ma: latex (25:75), (50:50) and (75:25) have met the standard values of 0.926, 1.022, and 1.175 n / mm2. the highest value of tensile strength of the sample in the comparison of pp-g-ma: latex (75: 25) at 1.175 n / mm2, this corresponds to the small surface pores of 0.728 µm and the high density 1.059 g / ml so that the strength between the matrix and the �ller on the thermoplastic elastomers have strong bond. it is proved by the largest tensile strength test value of 1.175 n / mm2. the linear relationship between tensile strength and elongation meet the standard bumper tensile test with a maximum of 22.62% while the standard maximum elongation is 22.62%. 4. conclusions based on ftir analysis, the without glycerine sample reaches the keton value of c = o with the highest absorption of 1703.48 cm−1 with absorption percentage of 94.84% and c-o carbonyl absorption of 1219 cm−1 with absorption percentage of 95.19%. this is because the grafting samples are pure and have not been emulsi�ed so that the intensity of the grafting is still high from the carbonic group co and c = o male anhydride. the stability testing of density values reaches the standard of the plastic federation of 0.91 1.30 g / ml, for samples having the highest and stable density values up to the seventh day of observation is a sample of pp-g-ma: latex (75:25) which is 1.059 g/ml. meanwhile, based on sem test on the ppg-ma © 2018 the authors. page 155 of 156 nur padmi et. al. science and technology indonesia, 3 (2018) 151-156 sample: latex (75:25) has a mean pore value of 1.408 µm and the smallest pore value at 0.728 µm. the highest value of tensile strength occurred in the sample with the comparison of pp-g-ma: latex (75:25) 1,175 n / mm2 and a breaking extension of 22.62%. references brydson, j. a. (1999). plastics materials. elsevier science deswita, sudirman, a. k. karo, s. sugiantoro, and a. handayani (2006). pengembangan termoplastik elastomer berbasis karet alam dengan polietilen dan polipropilen untuk bahan industri. jurnal sains materi indonesia, 8; 52–57 ismail, h. and suryadiansyah (2002). thermoplastic elastomers based on polypropylene/natural rubber and polypropylene/recycle rubber blends. polymer testing, 21(4); 389–395 meyer and j. keurentjes (2005). handbook of polymer reaction engineering. wiley-vch sondari, d., a. haryono, m. ghozali, a. randy, k. a. suhardjo, ariyadi, and surasno (2010). pembuatan elastomer termoplastik menggunakan inisiator potassium persulfate dan ammonium peroxydisulfate. jurnal kimia indonesia © 2018 the authors. page 156 of 156 introduction experimental section materials and tools procedure grafting polypropylene (pp) with maleate anhydride (ma) making pp-g-ma emulsion making pp-g-ma emulsion with natural rubber sensitive latex testing results and discussion fourier transform infrared test result (ftir) density test result thermoplastic elastomers surface morphology the result of mechanical properties of the thermoplastic elastomers disscusion conclusions article http://sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 29-36 article history received : 4 october 2016 received in revised form : 2 january 2017 accepted : 5 january 2017 doi: 10.26554/sti.2017.2.2.29-36 ©2017 published under the term of the cc by nc sa license adsorption of congo red using kaolinite-cellulose adsorbent santa oktavia ginting1*, risfidian mohadi1 1department of chemistry, faculty of mathematic and natural sciences sriwijaya university *corresponding author email: gintingsanta86@gmail.com abstract kaolinite was impregnated with cellulose extracted from rubber wood fibers has been done. the product of impregnated kaolinite-cellulose was characterized using ft-ir spectrophotometer. furthermore, the impregnation results are used as an adsorbent of congo red. adsorption of congo red was also studied the kinetic and thermodynamic parameters. the results of characterization using ft-ir spectrophotometer shows the process of impregnation was successfully conducted. it was indicated that the presence wavenumber at 910.4 918.12 cm-1 and 1033.85 cm-1 become 1026.13 cm-1 and the existence of vibration at wavenumber 2931.8 cm-1. the ph of adsorption was adjusted to 4 before the adsorption process. the adsorption process of cellulose impregnated kaolinite shows the rate of adsorption (k) of 0.002 min-1, the adsorption reviews largest capacity (b) at 50 °c was 500 mol/g. the greatest adsorption energy (e) at 40 °c is 11:09 kj/mol. the enthalpy value (δh) and entropy (δs) decreased with increasing congo red dye concentration. keywords: kaolinite, cellulose, impregnation, congo red introduction clay is a material that consists of mineral rich in alumina, silica, and water. clay mineral is layered silicate and commonly found in nature. one example of a layered material or clay is widely known that kaolinite (deng, et.al, 2017). the chemical formula of pure kaolinite is aluminum silicate hydrate (al 2 o 3 .2sio 2 .2h 2 o). the minerals include kaolinite group is kaolinite, nacrite, and halloysite, with its main mineral kaolinite (kovács and makó, 2016). in recent years, kaolinite has become the materials used for several of industrial processes due to its excellent performance like good bonding ability, a good electrical insulator, and thermal stability. however, it is rarely used as an adsorbent for the low cations exchange capacity and a small specific surface area (koteja and matusik, 2015). crystal structure of kaolinite is classified to the type phyllosilicates 1: 1. this crystal consists of sheets octahedral aluminum, al3+ coordinated to the anion ohstacked sheets of silica tetrahedral, si4+ coordinated to the anion o2(yu, et.al, 2016). as an inorganic polymer, kaolinite minerals classified as inorganic ion exchangers who can naturally perform the exchange process with other ions from the outside with the influence of water (chemeda, et.al, 2015). the clay structure is negatively charged and binding of cations to neutralize the charge. the negative charge is derived from the ratio between silica and alumina (si/al) which is relatively small and the surface of the kaolinite that has oxygen and hydroxyl groups sticking out, causing the negatively charged (pietzsch et.al, 2015). one of effort to improve the absorption of kaolin as an adsorbent can be modified by impregnation method. the impregnation is a process in which an adsorbent material that coats so that the active group of the material is also capable of binding the compound to be absorbed (aung et.al, 2015). impregnation technique can be done with certain organic materials and the process is easy and simple. organic materials that can be used to modify the clay are cellulose, cellulose used because its existence is abundant in nature. judging from the structure of cellulose has a huge potential to be used as adsorbent, because the -oh group that is bound to interact with the adsorbate. the presence of the -oh group in cellulose cause the polar properties on the adsorbent. thus stronger cellulose absorbs substances that are polar substances that are less polar (han et.al, 2016). studies of impregnation method have been carried out by unuabonah et.al (2007) that has impregnated tripolyphosphate to kaolinite for adsorption of lead and cadmium. chong et.al (2009) also reported impregnation of kaolinite using titania compound as material for photocatalyst. the dye used in the apparel industry, paper, plastic, rubber, food and cosmetics to produce a colored product. the dye usually has a complex molecular structure which makes it more stable aromatic so difficult to disentangle biodegradable. congo red is a dye that has an azo group (r n = n r). as the waste dye, where the dye congo red, especially in the aquatic environment can damage a variety of species of life because of the nature of dye congo red, which has a fairly high level of toxicity. if the dye congo red accumulates in the human body can cause several health problems in humans (sasmal et.al, 2017). treatment and removal of congo red from aqueous solution has been conducted by many researchers such as said and palapa (2017), which has mg/al hydrotalcite as material for adsorption of congo red. concern on the effects of the textile dye congo red on the environment and living beings in it, there should be efforts to minimize waste of the substance before being discharged into the water system. it requires an adsorbent that is able to absorb the dye better. kaolinite impregnated cellulose is expected to be used as an adsorbent with a higher adsorption capacity, especially for organic molecules. experimental section materials and equipments the materials used in this study are rubber wood fibers, kaolinite (al 2 o 3 .2sio 2 .2h 2 o), substance color congo red (c 32 h 22 nmailto:gintingsanta86@gmail.com ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 30 6 na 2 o 6 s 2), thiourea ((nh 2 ) 2 cs) and sulfuric acid (h 2 so 4), sodium hydroxide (naoh), hydrochloric acid (hcl), and distilled water (h 2 o). the tools used in this research that flask glassware, analytical balance, furnace, magnetic stirrer, thermometer, bath (hotplate), oven, horizontal shaker, filter paper, pipette volume, pipette, cuvette, spectrophotometers shimadzu ft-ir-prestige-21, and uv-vis spectrophotometer thermo scientific geneysis 20. preparation rubber wood fiber a 100 g of rubber wood fibers was washed using hydrochloric acid (hcl 0.1 m) with a certain volume for 3 hours while shaked. washing results then filtered, and the solids obtained were washed with water and followed by washing using 0.1 m naoh with a certain volume for 3 hours while shaked. results immersion then filtered, and the solids obtained were washed with water until the washing water has a neutral ph. then the solids are dried and the obtained results in the form of cellulose 1x washing characterized using ft-ir spectrophotometer. the characterization results compared to standard cellulose. the procedure is repeated from the beginning to get the cellulose 2x, 3x, and 4x wash. determination of water content the water content is determined by measuring the sample weight measurements before and after heating. a total of 1 g of rubber wood fibers incorporated into a petri dish of known weight. the wood fiber was heated in an oven at 110 °c for 5 hours, then allowed to stand and weighed. this procedure applies to launder 2x, 3x, and 4x to obtain a constant weight. determination of ash content the ash content is determined by incorporating 1 g of wood fiber (washed) in exchange porcelain that has been known weight. the wood fiber is heated into the furnace at a temperature of 400 °c for 2 hours to form ash, then allowed to stand and weighed. the procedure applies to launder 2x, 3x, and 4x to obtain cash heavy. preparation and activation kaolinite preparation kaolinite is done by two types i.e. physical and chemical activation. for physical activation, a 100 g of kaolinite was heated using the furnace at a temperature of 400 °c for 2 hours and then allowed to stand at room temperature. the kaolinite was named heated kaolinite. the other kaolinite was processed by chemical/acidification process. acidification is done by dissolving 20 g of kaolinite which has been heated at a temperature of 400 °c into 200 ml of sulfuric acid (h 2 so 4) the concentration of each 1%, 5%, 10%, and 15% in the beaker glass separately and stirred for 3 hours. once separated and filtered, then each dried solid at a temperature of 97 oc. further kaolinite which has been prepared called acidified kaolinite. natural kaolinite, heated kaolinite, and acidified kaolinite were characterized by using ft-ir spectrophotometer. impregnation kaolinite with cellulose impregnation process carried out as follow. kaolinite solids-cellulose was prepared by adding 4 g of cellulose from wood fiber rubber into a mixture of 1.5 m naoh solution and the solution of thiourea 1 m. the mixture was stored at 0 °c for 8 hours to obtain a solution (i). a 10 g of activated kaolinite mixed with naoh 46% as much as 8 ml in ice water for 6 hours. a 52 g of ice was added to obtain a solution (ii). the solution (i) and (ii) are mixed and stirred for 30 minutes to obtain a solid, and then filtered. the solid is filtered drip with sulfuric acid (h 2 so 4 ) 5% solids obtained are then dried and the impregnation result kaolinite-cellulose. results of kaolinite-cellulose impregnation characterized using ft-ir spectrophotometer. applications of cellulose fibers rubber wood (control), activated kaolinite and kaolinite impregnated cellulose as dye adsorbent congo red preparation of standard solution of congo red preparation of standard solution of dye congo red made by diluting the mother liquor dye congo red 1000 mg/l is used as a concentration of 10, 20, 30, 40 mg/l gradually. standard solution of dye congo red the adsorption by the adsorbent for the process of cellulose from wood fiber gum, kaolinite and kaolinite activated impregnated cellulose. furthermore, each standard solution concentration congo red measured wavelength of maximum absorbance at 503 nm using uv-vis spectrophotometer. having obtained the equation absorbance then made a straight line with the x-axis dye concentration congo red on the y-axis as absorbance. influence of time adsorption a 0.03 g of each adsorbent is added to 50 ml congo red with a concentration of 40 mg/l in a separate flask. the adsorbent was stirred with a horizontal shaker at predetermined intervals. the variation of the adsorption time starts at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 minutes. congo red that has gone through the adsorption process is separated and the absorbance was measured using a uv-vis spectrophotometer. the amount of residual concentrations (mg/l), the amount of dye congo red adsorbed (mg/l) was calculated using the equation of the calibration curve standard solution, while the rate of adsorption (k 1 ) can be calculated using the langmuir equation as shown in formula 1. influence of temperature and concentration of congo red effect thermodynamics congo red dye adsorption by cellulose (control), kaolinite activated (control) and kaolinite impregnated cellulose is done through a series of experiments with varying concentrations of dye congo red adsorption and temperature. a total of 0.03 g adsorbent cellulose (control) and kaolinite activated (control) were mixed with 50 ml of dye congo red (5, 10, 15, 20, 25 mg / l), and as much as 0.03 g kaolinite adsorbent impregnated cellulose mixed with 50 ml of dye congo red (10, 20, 30, 40 mg / l). the adsorbent which has been mixed with dye congo red is stirred using a horizontal shaker for 30 minutes at varying temperatures (30, 40, 50, 60 and 70 °c). the mixture is separated, then a solution of dye congo red that has separated from the adsorbent measured absorbance values using a uv-vis spectrophotometer to determine the concentration of residual dye congo red after the adsorption process. the adsorption capacity (b), the adsorption energy (e) can be calculated using the langmuir equation in formula 2 and 3, while the adsorption enthalpy (δh), and the adsorption entropy (δs) can be calculated using formula 4. data analysis the success of kaolinite with cellulose impregnation process was observed from ft-ir spectrum. impregnation process optimal expected to form the adsorbent can be applied to the process of adsorption of the dye congo red to see the parameters of kinetic and thermodynamic data kinetics of cellulose (control), kaolinite activated (control), and kaolinite impregnated cellulose is used to determine the rate of adsorption (k 1) assuming that the adsorption process that occurs following the model of the langmuir adsorption equation as ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 31 follows: ( )0 1 ln c c t k k c c = + (1) where: c 0 = initial concentration of congo red (mg/l) c = concentration of residual congo red (mg/l) t = adsorption time (min) k 1 = rate of adsorption (min-1) k = constant adsorption equilibrium thermodynamic parameters of cellulose impregnated kaolinite adsorption processes such as adsorption capacity and adsorption energy can be determined using the langmuir equation as follows: 1c c m bk b= + (2) e rt ln k (3) where: c = concentration of residual congo red (mg/l) m = mol of congo red adsorbed on kaolinite k = equilibrium constant b = adsorption capacity (mol/g) e = energy adsorption (kj/mol) r = constant t = temperature while to find the value of the distribution coefficient of adsorbate used the following equation: ln d h s k rt r ∆ ∆ = − + (4) description: k d = distribution coefficient of adsorbate (qe/ce) δh = enthalpy δs = entropy r = constant t = temperature results and discussion identification and characterization of cellulose results separation of wood fiber rubber using spectrophotometer ftir fiber rubber wood taken from wood processing waste already separated, so that the residue obtained in the form of a mixture of cellulose, lignin and hemicellulose. cellulose result of separation of rubber wood fibers identified using ft-ir spectrophotometer is then compared with the ft-ir spectrum of standard cellulose as presented in figure 1. in figure 1 looks ft-ir spectra of standard cellulose showed absorption at wavenumbers 3348.42 cm-1 which is the stretching vibration of the hydroxyl group (oh). wavenumber in 2900.94 cm-1 indicates -ch vibration which is a constituent group of the cellulose structure and reinforced with vibration at wave number 1427.32 cm-1 and 1373.32 cm-1. co group which is a carbon chain connecting the cellulose compound is located in the fingerprint region at wavenumber 1250-1030 cm-1 and a stretching vibration. ft-ir spectra of the cellulose separation results show similarities with the standard cellulose, which in the area of 3410.15 cm-1 the hydroxyl (oh), -ch group at wavenumber 2924.09 cm-1 and reinforced with vibration on wavenumber 1427.32 cm-1, 1373.32 cm-1 and 1327.03 cm-1 i.e. in the fingerprint region 1250-1050 cm-1 indicate the presence of ether groups (-co). in the ir spectra of cellulose from wood fiber rubber looks still their unwanted vibration that is at wave number 1600 1700 cm-1 that indicates aromatic compounds making up the structure of lignocellulose. therefore, necessary separation process can be continued in order in pure cellulose. cellulose separation of compounds undesirable done by soaking the back of cellulose using hydrochloric acid at a concentration of 0.1 m for three hours while stirring followed by immersion using sodium hydroxide at a concentration of 0.1 m with stirring for three hours. soaking using hcl intended to break the hemicellulose and lignocellulose while naoh solution is used to dissolve the lignin, hemicellulose and other compounds in order to get pure cellulose (taflick et.al, 2017). soaking using hcl and naoh are repeated four times in order to obtain increasingly pure cellulose. figure 1. ft-ir spectrum of (a) the separation of cellulose wood fibers rubber (b) standard cellulose figure 2. ft-ir spectrum of (a) standard cellulose; (b) the separation of the cellulose fibers rubber wood; cellulose washery 1x (c); 2x (d); 3x (e); 4x (f) ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 32 cellulose separation results are identified using a spectrophotometer ft-ir and spectra are then compared to standard cellulose. figure 2 show that the ft-ir spectrum of cellulose results 4x laundering has similarities with the standard cellulose ir spectra. especially in the area of 2368.59 cm wave number-1 where the ftir spectra of cellulose results showed absorption 4x laundering sharp and strong intensity in the region of the wave numbers compared to the ft-ir spectra of cellulose washery 1x, 2x and 3x. in the 1100-1600 cm-1, the absorption area for laundering proceeds 4x cellulose has similarities with ft-ir spectra showing the vibration standard cellulose -ch group. characterization of wood fibers cellulose rubber results washing through content determination of water and ash content. result of the determination content of moisture and ash content of cellulose from wood fiber rubber washing results are presented in table 1. water content like presented in table 1 shows the water can be removed by heating at a temperature of 100-110 °c. determination of the water content of an adsorbent conducted to determine the hygroscopic properties of the adsorbent because of high water in the adsorbent will reduce his ability as adsorbent due to pores are filled molecules of h 2 o (sharma et.al, 2017). in general, the desired moisture content has a low water content. it also deals with waku save fuel to be used which in this case is cellulose from wood fiber rubber washing results. if the high water content in the storage cellulose cannot be done in the long term and its use will be limited. in this study, cellulose from wood fiber washing results 4x repetition has the smallest water content. in the first washing, the cellulose has a water content by 6.52% while the fourth laundering cellulose has a water content of 1.98%. furthermore, the determination of ash content in the cellulose from wood fiber rubber washing results. the ash content indicates the rich content of metal oxides or mineral salts and impurities contained in the cellulose from wood fiber washing results. based on the national indonesian standard criteria for adsorbent ash content is a maximum of 2.5%. table 2 shows that the ash content of cellulose from wood fiber rubber decreases with decreasing water content. based on the data in table 2, it is known that cellulose from wood fiber washery four times has the lowest ash content is 0.92% in accordance with the terms of a maximum ash content of the adsorbent, to cellulose from the washing 1x, 2x, and 3x exceeds the maximum ash content of an adsorbent. identification and characterization of natural kaolinite and activation using ft-ir spectrophotometer kaolinite has the characteristics of the bond, si-o (wavenumber area around of 993, 1024, and 1112 cm-1), si-o-al (in the area around of 530 cm-1) and oh (in the wavenumber area around of 3684, 3668, 3651, and 3618 cm-1) (spence and kelleher, 2012). vibration typical kaolinite which show ties to the kaolinite presented in table 2. in figure 3a looks a typical absorption band at natural kaolinite in the area of wave number 3695.6 cm-1 and 3618.4 cm-1 that indicates al-oh stretch vibration which is characteristic of kaolinite. uptake in the area of 3448.7 cm-1 and 1635.6 to 2368.5 cm-1 may indicate vibration oh observed almost in all silicate hydrate. bond at 3448.7 cm-1 indicates the stretch vibration of hoh and 1635.6 cm-1 indicates hoh bending vibration. strong absorption band appears at wavenumber 1026.1 cm-1 and 1002 cm-1 which show the stretch vibration of si-o as tetrahedral layers of kaolinite, while uptake in areas 918.1 cm-1 indicates al-oh bending vibration as octahedral layers of kaolinite. vibration strain si-o-al appears at 547.7 cm-1, while the strong absorption bands appear on the area 470.6 cm-1 and 401.1 cm-1 that indicates the bending vibration of si-o-si (saikia and parthasarathy, 2010). natural kaolinite which has been characterized using ft-ir spectrophotometer is then performed the activation process. there are two stages in the activation process kaolinite namely heating at 400° c for two hours and acidification using sulfuric acid (h 2 so 4 ) with various concentrations of 1%, 5%, 10% and 15%. activation by heating at a temperature of 400o c aims to remove impurities such as alkali metal or alkaline earth metal contained in the natural kaolinite (gao et.al, 2016). absorption bands seen in figure 3b table 1. the moisture content and ash content of cellulose from wood fiber washing washing water content (%w/w) ash content (%w/w) 1 6.52 6.86 2 4.85 6.73 3 3.96 6.00 4 1.98 0.92 table 2. data for kaolinite wave numbers wavenumbers (cm-1) vibrations 3670-3656 bend (al-oh) 3435-3433 bend hoh 1635-1629 hoh stretch 1100-1005 bend the si-o 916-915; 888-842 o-h deformation bound cations 542-535 bending si-o-al 475-468 stretch si-o-si (saikia et al, 2010) figure 3. ft-ir spectrum of (a) a natural kaolinite; (b) kaolinite heating; and acidification result kaolinite h 2 so 4 (c) 1%; (d) 5%; (e) 10%; and (f) 15% ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 33 shows the shift in the bending vibration of si-o appearing at wave number 1018.4 cm-1 and stretch vibration of si-o-al appearing at 540.07 cm-1. al-oh stretch vibrational still appears at wave number 3695.6 cm-1 and 3618.4 cm-1. vibration bend and stretch hoh appear on the same wave numbers with natural kaolinite, which is 3448.7 cm-1 and 1635.6 cm-1. vibration bending si-o-si remains on the wave number of 470.6 cm-1. for activation using strong acids will produce kaolinite with active sites larger and larger surface acidity that will produce kaolinite with a higher adsorption capacity than before is activated (wang et.al, 2016). from figure 3 presented shows that the ft-ir spectrum of shifting, especially again in figure 3e which result kaolinite acidification h 2 so 4 10%. absorption bands seen in figure 3e shows the shift of the hoh bending vibration that appears at wave number 3387 cm-1, si-o stretch vibration that appears at wave number 1103.2 cm-1 and 1033.8 cm-1 and bending vibration al oh which appears at wave number 910.4 cm-1. al-oh vibrational strain persists at 3695.6 cm-1. vibration stretch hoh remains on the wave number 1635.6 cm-1. identification and characterization of kaolinite result of impregnation with wood fibers cellulose rubber using ftir spectrophotometer impregnation process kaolinite with rubber wood cellulose fiber made from mixing the two solutions. the solution i consisted of a mixture of 1.5 m naoh and thiourea 1 m and then added cellulose from wood fiber 4x rubber washing results. solution ii consists of kaolinite results of acidification h 2 so 4 10% and 46% naoh is added and ice cubes. the ftir spectrum of kaolinite was presented in figure 4. from the figure 4, it seen there are several groups making up the cellulose structure which -ch vibration that appears at wave number 2931.8 cm-1 and strengthened also by the emergence of vibration in wave numbers 1465.9 cm-1 and 1342.4 cm-1. this suggests that the cellulose compound capable of sticking and bonding with kaolinite. absorption bands are seen in figure 4c. from the figure 4, it can see the shift of the hoh bending vibration that appears at wave number 3464.1 cm-1 with a strong intensity. al-oh vibrational stretch that is characteristic of kaolinite persists at 3695.6 cm-1. si-o vibrational stretch as tetrahedral layers of kaolinite and al-oh bending vibration as octahedral layers of kaolinite persists at 1026.1 cm-1, 1010.7 cm-1 and 918.1 cm-1. vibration strain si-o-al remains on the wave number 540.07 cm-1 and bending vibrations of si-o-si also persists in the area of 470.6 cm-1 and 432.05 cm-1. vibrations that appear in the ft-ir spectrum of figure 4c has a lower intensity, due to the merger of two of the compounds causing the concentration contained in each of these compounds is reduced. impregnation process involves physical interaction between cellulose impregnated with kaolinite. this physical interaction occurred at the surface and are the result of physical force or involve intermolecular forces such as van der waals bonding. the success of the impregnation process can be seen in the ft-ir spectrum of figure 4 wherein the cellulose constituent is -ch group appears at wave number 2931.8 cm-1 and reinforced with vibration at wave number 1465.9 cm-1 and 1342.4 cm-1 kaolinite and the new ft-ir spectrum is shown in figure 4c. effect of time adsorption of dye congo red using adsorbents kaolinite activated (control), cellulose results laundering (control), and kaolinite impregnated cellulose and determination of kinetic parameters effect of adsorption time to dye adsorption congo red is done by encounters 0.03 g each adsorbent with dye solution is congo red 50 ml with a concentration of 40 mg/l. the adsorption process carried out with stirring during the adsorption contact time varied i.e. for 10 to 120 minutes. the observation of the effect of contact time dye adsorption congo red with activated kaolinite, cellulose washery and kaolinite impregnated cellulose can be seen in figure 5. figure 5 shows a concomitant increase in the adsorption amount of congo red is absorbed relatively increased. at adsorbent cellulose from wood fibers visible rubber dye number congo red increased continuously in time from 10 minutes to 70 minutes, but a decline in the next adsorption time increment. at the time of 70 minutes showed amount of congo red the greatest adsorbed i.e. 2.08 mg/l. on kaolinite adsorbent activated seen amount congo red adsorbed increased in 10 minutes to the 80 minutes. at the time of 80 minutes showed amount of congo red the greatest adsorbed i.e. 36.29 mg/l. whereas in kaolinite adsorbent impregnated cellulose also showed an increase in the time of 10 minutes until 40 minutes. at 60 minutes the amount of congo red adsorbed decreased, but increased again to 70 minutes and further declined in the next time increment. at 70 minute, kaolinite impregnated celluwave numbers (cm-1) figure 4. ft-ir spectrum of (a) kaolinite result of acidification of h 2 so 4 10%; (b) the cellulose of the wood fibers result laundering 4x; (c) kaolinite impregnated cellulose from wood fiber rubber figure 5. effect of contact time congo red 40 mg / l with adsorbent cellulose from wood fiber gum (control), kaolinite activated (control), and kaolinite impregnated cellulose to the amount of congo red adsorbed ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 34 lose has the number of congo red largest adsorbed i.e. 8.75 mg/l. adsorption time data in figure 5 can be used to determine the kinetic parameters of adsorption. adsorption rate constant (k1) congo red on each adsorbent using langmuir-hinshelwood equation. data adsorption rate constant dye congo red on each adsorbent is presented in table 3. table 3 shows that the activated kaolinite adsorbent having adsorption rate (min-1) that is larger 0.026 min-1, kaolinite adsorbent impregnated cellulose has the adsorption rate of 0.002 min-1 while the adsorbent cellulose from wood fiber rubber have very little adsorption rate which is equal to 0.001 min-1. this is because adsorbate that in this study dye congo red adsorbed on an adsorbent layer and the surface of the kaolinite activated causing the adsorption rate faster than kaolinite adsorbent impregnated cellulose and cellulose from wood fiber gum. whereas in kaolinite adsorbent impregnated cellulose from wood fiber and rubber adsorption occurs in physics involving van der waals bonds, so that the adsorption rate is slower. effect of temperature and concentration of congo red and determination of thermodynamic parameters the effect of congo red dye adsorption temperature by cellulose adsorbents from rubber wood fibers, activated kaolinite, and cellulose impregnated kaolinite is presented in figure 6, 7 and 8. in figure 6, 7, and 8 it is seen generally that the greater the temperature (oc) and the concentration (mg/l) the amount of congo red adsorbed (mg/l) is also relatively increased, but some are decreasing at some temperature and concentration. the adsorption thermodynamic parameters include adsorption capacity (b), adsorption energy (e), enthalpy (δh), and entropy (δs). the adsorption capacity data for each adsorbewnt is presented in table 4. table 4 shows that the activated kaolinite adsorbent has the largest adsorption capacity of 1000 mg/g at 70 °c, whereas the cellulose impregnated kaolinite adsorbent and the cellulose adsorbent of rubber wood fibers at 40 °c and 50°c have the largest adsorption capacity of 500 mol / g and 125 mol / g. in table 4 also presents the adsorption energy data (e) which shows on every adsorbent in general an increase in adsorption energy as temperature increases. in the cellulose adsorbent of rubber wood fibers (control) has the greatest energy at 50 °c of 4.96 kj /mol, the activated kaolinite adsorbent (kaolinite) at 70 oc has the greatest energy of 10.22 kj/ mol, the impregnated kaolinite adsorbent at 40 °c has the greatest energy of 11.09 kj/mol. the value of adsorption energy can be used to determine the type of adsorption that occurred i.e. physical adsorption or chemical adsorption (isahak et.al, 2013). thus the adsorption in this research can be classified as physical adsorption. other thermodynamic parameters, such as enthalpy (δh) and entropy (δs) are presented in table 5. the entropy value (δs) of congo red adsorption by each of the adsorbents presented in table 5 indicates a decrease in the degree of irregularity with increased congo red (mg/l) concentration. this shows the regularity of the congo red dyestuff absorbed on each adsorbent. in addition to the enthalpy value (δh) of congo red adsorption also decreases with increasing concentration. conclusion the impregnation process involves the physical interaction between kaolinite and impregnated cellulose. this physical interaction occurred involving van der waals interaction. from the ft-ir spectrum data the kaolinite impregnation process with successful cellulose is characterized by wavenumbers 432.05 cm-1, 918.12 cm-1, 1026.13 cm-1 and the appearance of peaks at wave numbers 2931.8 and 1465.9 cm-1 which shows the presence of the -ch group as the structural constituent of cellulose. the adsorption process is studied through parameters of adsorption time, temperature, and congo red concentration. the activated kaolinite adsorbent (control) adsorption process was optimum at 80 minutes, 70 oc and 5 mg/l with adsorption energy table 3. parameter kinetic adsorption of congo red to the adsorbent cellulose from wood fiber, activated kaolinite, and kaolinite impregnated cellulose adsorbent k 1 (min-1) activated kaolinite 0.026 impregnated kaolinite 0.002 cellulose 0.001 figure 6. the effect of adsorption temperature and congo red dye concentration on the amount of congo red adsorbed by adsorbent of cellulose from rubber wood fiber figure 7. the effect of adsorption temperature and congo red dye concentration on the amount of congo red is adsorbed by activated kaolinite figure 8. the effect of adsorption temperature and congo red dye concentration on the amount of congo red is adsorbed by impregnated cellulose kaolinite ginting et al. 2017/science & technology indonesia 2 (2) 2017:29-36 © 2017 published under the term of the cc by nc sa 4.0 licence 35 of 10.22 kj/mol. the impregnated cellulose kaolinite adsorbent undergoes optimum adsorption at 70 minutes, 40 °c and 10 mg/l concentration with adsorption energy of 11.09 kj/mol. the cellulose adsorbent of rubber wood fibers undergoes optimum adsorption process at 90 min, 50 oc and 5 mg /l with adsorption energy of 4.96 kj/mol. in this study showed that adsorption occurs in the form of physical adsorption. acknowledgement the author would like to thank integrated research laboratory graduate school, sriwijaya university for laboratory equipment and support of this research. references aung. l.l., tertre. e., petit. s. 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(2016). pore-size changes and responses of kaolinite with different structures subject to consolidation and shearing. engineering geology, 202, 122131. _goback title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 2, april 2019 research paper counting the sum of cubes for lucas and gibonacci numbers wamiliana1*, suharsono1, p. e. kristanto2 1dept. of mathematics, universitas lampung, jl. soemantri brojonegoro no. 1, bandarlampung, indonesia 2smp xaverius 1, jl. sultan hasanuddin no. 20, telukbetung, bandarlampung, indonesia *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstract lucas and gibonacci numbers are two sequences of numbers derived from a welknown numbers, fibonacci numbers. the di�erence between lucas and fibonacci numbers only lies on the first and second elements. the first element in lucas numbers is 2 and the second is 1, and nth element, n ≥ 3 determined by similar pa�ern as in the fibonacci numbers, i.e : ln = ln-1 + ln-2. gibonacci numbers g_0,g_1,g_2,g_3. . . ; g_n=g_(n-1)+g_(n-2) are generalized of fibonacci numbers, and those numbers are nonnegative integers. if g_0=1 and g_1=1, then the numbers are the wellknown fibonacci numbers, and if g_0=2 and g_1=1, the numbers are lucas numbers. thus, the di�erence of those three sequences of numbers only lies on the first and second of the elements in the sequences. for fibonacci numbers there are quite a lot identities already explored, including the sum of cubes, but there have no discussions yet about the sum of cubes for lucas and gibonacci numbers. in this study the sum of cubes of lucas and gibonacci numbers will be discussed and showed that the sum of cubes for lucas numbers is ∑ni=0 (li)3= ln(ln+1) 2+5(−1)nln−1 + 19 2 and for gibonacci numbers is ∑ n i=0 (gi) 3= [gn(gn+1) 2+(g1−g0)3−3g02g1+4g03−(−1)n(g12−g1g0−g02)gn−1] 2 keywords fibonacci numbers, lucas numbers, gibonacci numbers, identities, sum of cubes received: 11 februari 2019, accepted: 8 april 2019 https://doi.org/10.26554/sti.2019.4.2.31-35 1. introduction fibonacci number was originally stated by leonardo pisano or fibonacci in his book, liber abaci in 1202. in his book he stated a problem about the growth of pairs rabbits. a young pair of rabbits (male and female) is placed on an island. a pair of rabbits does not breed until they are two months old. after they are two month old, each pair of rabbits produces another pair each month. assuming that there are no rabbits ever die then the total number of pair of rabbits form a sequence 1,1,2,3,5,8,13,...and this sequence of numbers is known as fibonacci numbers. lucas number was introduced by françois edouard anatole lucas in 1877 by setting the �rst number is 2 and the second is 1, and the other numbers are following the pattern as on fibonacci numbers so that it form a sequence of numbers 2, 1, 3, 4, 7, 11, 18, 29, 47,. . . gibonacci numbers g0,g1,g2,g3,...;gn = gn−1 + gn−2 are generalized of fibonacci numbers, and those numbers are nonnegative integers. if g0 = 1 and g1 = 1,then the numbers are the welknown fibonacci numbers, and if g0 = 2 and g1 = 1, the numbers are lucas numbers. thus, the di�erence of those three sequence of numbers only lies on the �rst and second of the elements in the sequences. there are many identities already developed that related among gibonacci, fibonacci, and lucas numbers. posamentier et al. (2007) showed that fibonacci, lucas, and gibonacci numbers related to pascal triangle, art and golden ratio. there are some researchers already investigated identities for fibonacci lucas and gibonacci numbers such as carlitz et al. (1972a,b,c,d), and benjamin et al. (1999, 2000, 2009, 2003). krishna (1980), investigated generalized fibonacci sequence and william (1972) discussed how to get fibonacci numbers from pascal’s triangle. dunlap (2003) investigated about the golden ratio and generalized fibonacci numbers, including the application in biology and crystallography. benjamin et al. (2003) proved more than one hundred fibonacci identities by combinatorial arguments and benjamin et al. (2009) proposed the identity for �nding the sum of cubes for fibonacci numbers. frontczak (2018) discussed about the relationship of sum of powers for fibonacci and lucas numbers for sum of �rst, second, third, and fourth powers; and arangala et al. (2016) investigated the relationship of the sum of power for fibonacci and lucas numbers for the power of square, fourth, sixth, and eighth. however, until recently there have no discussion about the sum of cubes for lucas numbers where in the formula just contains the lucas numbers itself, or the sum of cubes for gibonacci numbers where in the formula just contains the gibonacci numbers itself. therefore, in this study we will discuss about the sum of cubes for gibonacci numbers as an https://doi.org/10.26554/sti.2019.4.2.31-35 wamiliana et. al. science and technology indonesia, 4 (2019) 31-35 extension identity of koshy (2001), and benjamin et al. (1999). in section 2 and 3 we will present the results from koshy (2001), benjamin et al. (1999), and dunlap (2003), and in section 4 we will present the results. 2. some identities for lucas and gibonacci numbers 2.1 some identities for lucas number the identity 1, 2, and 3 are proposed by koshy (2001), and the identity 4 is proposed by benjamin et al. (1999). identity 1 l0 + l1 + l2 + ... + ln = ln+2 − l1 proof. using the de�nition of lucas number we get ln−2 = ln − ln−1 then, l0 = l2 − l1 l1 = l3 − l2 l2 = l4 − l3 l3 = l5 − l4 . . . ln−1 = ln+1 − ln take the sum on both sides simultaneously we get : l0 + l1 + l2 + l3+...+ln = ln+2 − l1 identity 2 l0 + l1 + l2 + l3 + ... + l2n = l2n+1 − l1 proof. by de�nition, ln−1 = ln − ln−2 then, l0 = l0 l2 = l3 − l1 l4 = l5 − l3 l6 = l7 − l5 . . . l2n−2 = l2n−1 − l2n−3 l2n = l2n+1 − l2n−1 take the sum on both sides simultaneously we get : l0 + l1 + l2 + l3+...+l2n = l2n+1 − l1 + l0 = l2n+1 − 1 + 2 = l2n+1 + 1 = l2n+1l1 identity 3 l1 + l3 + l5+...+l2n−1 = l2n − l0 proof. by de�nition, ln−1 = ln − ln−2 then, l1 = l2 − l0 l3 = l4 − l2 l5 = l6 − l4 . . . l2n−3 = l2n−2 − l2n−4 l2n−1 = l2n − l2n−2 take the sum on both sides simultaneously we get : l1 + l3 + l5+...+l2n−1 = l2n − l0 identity 4 ln+1ln−1 = ln2 − (−1)n⋅5 proof. using mathematical induction, and we leaven the basic induction and just do the induction step. asumme that the statement is true for n = k , lk+1lk−1 = lk2 − (−1)k⋅5 for n = k + 1, then : lk+12 = lk+1⋅lk+1 lk+12 = (lk+2 − lk)lk+1 lk+12 = lk+2⋅lk+1 lk⋅lk+1 lk+12 = lk+2 − (lk + lk−1)-lk⋅lk+1 lk+12 = lk+2lk + lk−1+lk+2⋅lk−1 − lk⋅lk+1 lk+12 = lk+2lk + (lk−1 + lk)lk−1⋅lklk+1 lk+12 = lk+2lk+lk+1lk−1 + lk⋅lk−1 − lk⋅lk+1 lk+12 = lk+2lk + lk+1⋅lk−1 + lk(lk+1 − lk−1) lk+12 = lk+2lk + lk+1lk−1 + lk(−lk) lk+12 = lk+2lk + lk+1lk−1−lk2 since, lk−1lk+2=−lk2−(−1) k⋅5, then lk+12=lk+2⋅lk−(−1) k⋅5 lk+12=lk+2⋅lk+(−1) k + 1⋅5 lk+2⋅lk=lk+12+(−1) k + 1⋅5 2.2 some identities for gibonacci number the identity 5,6, and 7 are proposed by dunlap (2003), identity 8 is proposed by benjamin et al. (2009), while identity 9 derived from de�nition 8. those identity will be used in the process to determine the sum of cubes for gibonacci numbers. identity 5 g0 + g1 + g2+...+gn = gn+2 − g1 proof. using the de�nition of gibonacci numbers, we get gn−2 = gn − gn−1 then, g0 = g2 − g1 g1 = g3 − g2 g2 = g4 − g3 g3 = g5 − g4 . . . gn−1 = gn+1 − gn gn = gn+2 − gn+1 take the sum of both sides simultaneously we get: g0 + g1 + g2+...+gn = gn+2 − g1 identity 6 g0 + g1 + g2 + g3+...+g2n = g2n+1 + g0 − g1 © 2019 the authors. page 32 of 36 wamiliana et. al. science and technology indonesia, 4 (2019) 31-35 proof. again, using the de�nition of gibonacci numbers, we get gn−1 = gn − gn−2, g0 = g0 g2 = g3 − g1 g4 = g5 − g3 g6 = g7 − g5 . . . g2n−2 = g2n−1 − g2n−3 g2n = g2n+1 − g2n−1 take the sum of both sides simultaneously we get : g0 + g1 + g2 + g3+...+g2n = g2n+1 + g0 − g1 identity 7 g1 + g3 + g5+...+g2n−1 = g2n − g0 proof. gn−1 = gn − gn−2 then, g1 = g2 − g0 g3 = g4 − g2 g5 = g6 − g4 . . . g2n−3 = g2n−2 − g2n−4 g2n−1 = g2n − g2n−2 take the sum on both sides simultaneously we get : g1 + g3 + g5+...+g2n−1 = g2n − g0 identity 8 gn+1gn−1 = gn2 − (−1)n⋅{g12 − g1g0 − g02} proof. by using mathematical induction. for n = k + 1, then : g2⋅g0 = gn2 − (−1)n⋅{g12 − g1g0 − g02} (g1 + g0)g0 = g12 − g12 − g1g0 − g02 g1g0 + g02 = g1g0g02 assume that the statement is true for n = k, then gk+12 = gk+1⋅gk+1 gk+12 = (gk+2 − gk)gk+1 gk+12 = gk+2⋅gk+1 gk⋅gk+1 gk+12 = gk+2 − (gk + gk−1)-gk⋅gk+1 gk+12 = gk+2gk + gk−1+lk+2⋅gk−1 − gk⋅gk+1 gk+12 = gk+2gk + (gk−1 + gk)gk−1⋅gkgk+1 gk+12 = gk+2gk+gk+1gk−1 + gk⋅gk−1 − gk⋅gk+1 gk+12 = gk+2gk + gk+1⋅gk−1 + gk(gk+1 − gk−1) gk+12 = gk+2gk + gk+1gk−1 + gk(−gk) gk+12 = gk+2gk + gk+1gk−1−gk2 because, gn+1gn−1 = gn2 − (−1)n⋅{g12 − g1g0 − g02} then gk+12=gk+2⋅gk−(−1) k⋅{g12 − g1g0 − g02} gk+12=gk+2⋅gk+(−1) k + 1⋅{g12 − g1g0 − g02} we get gk+2⋅gk=gk+12+(−1) k + 1⋅{g12 − g1g0 − g02} the following identity was derived from identity 8 identity 9 2gn2=gn+12−gngn−1 − (−1)n(g12 − g1g0 − g02) proof. gn2=gn⋅gn gn2=gn⋅(gn+1 − gn−1) gn2=gn⋅gn+1−gn⋅gn−1 gn2=(gn+1 − gn−1)⋅gn+1 − gn⋅gn−1 gn2=gn+12−gn+1⋅gn−1 − gn⋅gn−1 using identity 4 gn+1gn−1 = gn2 − (−1)n⋅{g12 − g1g0 − g02} then: gn2=gn+12{gn2 − (−1)n⋅(g12 − g1g0 − g02)}⋅gn−1 − gn⋅gn−1 2gn2=gn+12−gngn−1 − (−1)n(g12 − g1g0 − g02) 3. sum of cubic for lucas and gibonacci numbers based on the de�nition above, we can derive an de�nition for �nding the sum of cubes for lucas and gibonacci number as follow: identity 10 the sum of cubic of lucas numbers is ∑ni=0 (li) 3= ln(ln+1) 2+5(−1)nln−1 + 19 2 proof. using identity 5: 2ln2=ln+12−lnln−1 − (−1)n⋅5, then 2l03 = 2l03 2l13 = 2l1l12 2l13 = l1(l22l1l0 + (−1)15) 2l13 = l1l22 − l12⋅−5l1 2l23 = 2l2l22 2l23 = l2(l32l2l1 + (−1)15) 2l23 = l2l12 − l22⋅−5l1 2l33 = 2l3l32 2l33 = l3(l42l3l2 + (−1)15) 2l33 = l3l42 − l32⋅−5l1 2l43 = 2l4l42 2l43 = l4(l52l4l3 + (−1)15) 2l43 = l4l32 − l42⋅−5l1 2l53 = 2l5l52 2l53 = l5(l62l5l4 + (−1)15) 2l53 = l5l42 − l52⋅−5l1 2l63 = 2l6l62 2l63 = l6(l72l6l5 + (−1)15) 2l63 = l6l52 − l62⋅−5l1 . . . 2ln3 = 2lnln2 2ln3 = ln(ln+12lnln−1 + (−1)15) 2ln3 = lnln−12 − ln2⋅−5l1 take the sum on both sides simultaneously we get : 2(l03 + l13 + l23 + l33+...+ln3) 2(l03 − l12l0 − 5(l1 − l2 + l3 − l4 + l5 − l6 + ... − (−1)nln)lnl2n+1 lnl2n+1 − 5(l1 − l2 + l3 − l4 + l5 − l6+...−(−1) nln2(l03 − l12l0 © 2019 the authors. page 33 of 36 wamiliana et. al. science and technology indonesia, 4 (2019) 31-35 next, we need to �nd the sum of l1 − l2 + l3 − l4 + l5 − l6+...−(−1)nln by using identity 2 and 3, we get: −l2 − l4 − l6+...l2n = −(l2n+1 + l1 − l0) (1) −l1 − l3 − l5+...l2n−1 = −(l2n − l0) (2) from equation (3), adding both sides with l2n − l0, equation (3) becomes: −l2 − l4 − l6+...l2n + l2n − l0 = −(l2n+1 + l1 − l0) − (l2n − l0) (3) by using equation (4), equation (5) becomes : −l2 − l4 − l6 + ...l2n + (−l1 − l3 − l5+...l2n−1) = −(l2n+1 + l1 − l0) − l2n − l0 l1 − l2 + l3 − l4 + l5 − l6 + ... + l2n−1 − l2n = −l2n+1 + l1 − l0 − l2n − l0 = −l2n+1 + l1 − l2n = −l2n−1 − l2n (4) adding l2n+1 to both sides of equation (5), we get : l1 − l2 + l3 − l4 + l5 − l6 + ...l2n−1 − l2n + l2n+1 = −l2n−1 − l1 + l2n+1 l1 − l2 + l3 − l4 + l5 − l6 + ...l2n−1 − l2n + l2n+1 = l2n+1 − l2n−1 − l1 tℎus, l1 − l2 + l3 − l4 + l5 − l6 + ...l2n−1 − l2n + l2n+1 = l2n − l1 (5) by equation (6) and (7), we can conclude that : l1 −l2 +l3 −l4 +l5 −l6 + ...−(−1)nln = −(−1)nln−1 − l1 (6) therefore, by using equation (8), equation (3) becomes: 2(l03 + l13 + l23 + l33+...+ln3) = lnl2n+1 − 5[−(−1) nln−1 − l1]2(l03 − l12l0 = l2n+1 + 5(−1) nln−1 + 5l1 + 2l03 − l12l0 (7) by using de�nition that l0 = 2 and l1 = 1, then: 2(l03 + l13 + l23 + l33+...+ln3) = lnl2n+1 − 5[−(−1) nln−1 + 5 + 16 − 2 = lnl2n+1 − 5[−(−1) nln−1 + 19 tℎeref ore ∶ n ∑ i=0 (li)3 = ln(ln+1)2 + 5(−1)nln−1 + 19 2 example : given lucas sequence : 2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, 199, . . . , then 2(l03 + l13 + l23 + l33 + ... + l103) = l10(l11)2 + 5(−1)10l9 + 19 2 = 123(199)2 + 5(−1)1076 + 19 2 = 123(39601) + 5(−1)1076 + 19 2 = 4870923 + 380 + 19 2 = 2435661 by using direct summation we get : 2(l03 + l13 + l23 + l33 + ... + l103) = 23 + 13 + 33 + 43 + 73 + 113 + 183 + 293 + 473 + 763 + 1233 = 8 + 1 + 27 + 64 + 343 + 1331 + 5832 + 24389 + 103823+ 438976 + 1860867 = 2435661 identity 11 ∑ni=0 (gi)3= gn(gn+1) 2 + g1 − g03 − 3g02g14g03−(−1)n(g12 − g1g0 − g02)gn−1 2 proof. by using identity 9: 2gn2=gn+12−gngn−1 − (−1)n(g12 − g1g0 − g02) 2g03 = 2g03 2g13 = 2g1g12 2g13 = g1(g2 − g1g0 − (−1)n(g12 − g1g0 − g02)) 2g13 = g1g22 − g22⋅g0 + (g12 − g1g0 − g02)g1 2g23 = 2g2g22 2g23 = g2(g3 − g2g1 − (−1)n(g12 − g1g0 − g02)) 2g23 = g2g32 − g32⋅g0 + (g12 − g1g0 − g02)g2 2g33 = 2g3g32 2g33 = g3(g4 − g3g2 − (−1)n(g12 − g1g0 − g02) 2g33 = g3g42 − g42⋅g0 + (g12 − g1g0 − g02)g3 2g43 = 2g4g42 2g43 = g4(g5 − g3g3 − (−1)n(g12 − g1g0 − g02)) 2g43 = g4g52 − g52⋅g0 + (g12 − g1g0 − g02)g4 2g53 = 2g5g52 2g53 = g5(g6 − g4g2 − (−1)n(g12 − g1g0 − g02)) 2g53 = g5g62 − g52⋅g0 + (g12 − g1g0 − g02)g5 2gn3 = 2gngn2 2gn3 = gn(gn+1 − gngn−1 − (−1)n(g12 − g1g0 − g02)) 2gn3 = gngn+12 − gn2⋅gn−1(−1)n(g12 − g1g0 − g02)gn © 2019 the authors. page 34 of 36 wamiliana et. al. science and technology indonesia, 4 (2019) 31-35 by taking the sum of both sides simultaneously we get: 2(g03 + g13 + g23 + g33+...+gn3) = 2g03 − g12.g0 +(g12 − g1g0 − g02)(g1 − g2 + g3 − g4 + g5 − g6 +... − (−1)ngn) + gngn+12 (8) next, we need to �nd (g1 − g2 + g3 − g4 + g5 − g6+...−(−1)ngn) + gngn+12 by using identity 2, we get : −g2 − g4 − g6...−g2n = −(g2n+1 − g1) (9) and identity 7: g1 + g3 + g5...+g2n−1 = g2n − g0 (10) from equation (11), add both sides of the equation with g2n − g0 then equation (12) becomes : −g2−g4−g6...−g2n +g2n −g0 = (g2n−1−g1)+g2n −g0 (11) by equation (12), equation(13) will be : −g2 − g4 − g6... − g2n + g2n + g1 + g3 + g5... + g2n−1 = (g2n−1 − g1) + g2n − g0 g1 − g2 + g3 − g4 + g5 + g6 + ... + g2n−1 − g2n = g2n−1 + g2n + g1 − g0 (12) from equation (13), add both sides withg2n+1, we get: g1 − g2 + g3 − g4 + g5 + g6+...+g2n−1 − g2n + g2n+1 = g2n−1 + g1 − g0 + g2n+1 = g2n+1 − g2n−1 + g1 − g0 by using the de�nition we get g2n = g2n+1 − g2n−1 thus, g1 − g2 + g3 − g4 + g5 + g6 + ... + g2n−1 − g2n + g2n+1 = g2n + g1 − g0 (13) from equations (14) and (15), we can conclude that : g1 − g2 + g3 − g4 + g5 − g6 + ... − (−1)ngn = −(−1)ngn−1+ + g1 − g0 (14) by using equation (16), equation (17) become: 2g30 + g 3 1 + g 3 2 + g 3 3 + ... + g 3 n = 2g30 − g 2 1 .g0 + (g 2 1 − g1g0 − g 2 0) [−(−1)ngn−1 + g1 − g0] + gng2n+1 = gng2n+1 + 2g 3 0 − g 2 1g0− (−1)n + g21 − g1g0 − g 2 0gn−1 + g1 − g0 = gng2n+1 + 2g 3 0 − g 2 1 .g0 + (g 2 1 − g1g0 − g 2 0) [−(−1)ngn−1 + (g21 − g1g0 − g 2 0)(+g1 − g0) = gng2n+1 + 2g 3 0 − g 2 1g0 + (g 2 1 − g1g0 − g 2 0) (+g1 − g0) − (−1)n(g21 − g1g0 − g 2 0)gn−1 = gng2n+1 + 3g 3 0 − g 3 13g 2 1g0− (−1)n(g21 − g1g0 − g 2 0)gn−1 = gng2n+1 + (g1 − g0) 3 + 4g30 − 3g 2 0g1− (−1)n(g21 − g1g0 − g 2 0)gn−1 (15) therefore: g03 + g13 + g23+...+gn3= [gn(gn+1)2+(g1−g0)3−3g02g1+4g03−(−1)n(g12−g1g0−g02)gn−1] 2 example : for g0 = 3 and g1 = 2 , the gibonacci sequence is 3, 2, 5, 7, 12, 19, 31, 50, 81, 131, 212,. . . g03 + g13 + g23+...+g93= [g9(g10)2+(g1−g0)3−3g02g1+4g03−(−1)9(g12−g1g0−g02)g8] 2 g03 + g13 + g23+...+g93= [131(212)2+(2−3)3−3322+443−(−1)9(22−23−3)281] 2 g03 + g13 + g23+...+g93= [(131)(44944)−1−54−108+(−11)81] 2 g03 + g13 + g23+...+g93= [5887664−1λ54+108−891] 2 =2943413 by using direct summation we get : g03 + g13 + g23+...+g93= 33 + 23 + 53 + 73 + 123 + 193 + 313 + 503 + 813 + 1313 = 9 + 8 + 125 + 343 + 1728 + 6859 + 29791 + 125000 + 531441 + 2248091 = 2943413 4. conclusions from the discussion above we can conclude that the sum of cubic for lucas number is l03 + l13 + l23 + l33+...+ln3= ∑ni=0 (li)3= ln(ln+1) 2+5(−1)nln−1 + 19 2 and for gibonacci numbers is g03 + g13 + g23 + g33+...+gn3= ∑ni=0 (gi) 3= [gn(gn+1) 2+(g1−g0)3−3g02g1+4g03−(−1)n(g12−g1g0−g02)gn−1] 2 references arangala, c., b. hrovat, and j. kelner (2016). sum of powers of fibonacci and lucas numbers. the minnesota journal of undergraduate mathematics, 2(1); 1–12 benjamin, a. t, t. a. carnes, and b. cloitre (2009). recounting the sums of cubes of fibonacci numbers. congressus numerantium, proceedings of the eleventh international conference © 2019 the authors. page 35 of 36 wamiliana et. al. science and technology indonesia, 4 (2019) 31-35 on fibonacci numbers and their applications. william webb, ed, 194; 45–51 benjamin, a. t, and j. j. quinn (1999). recounting fibonacci and lucas identities. college mathematics journal, 30(5); 359 – 366 benjamin, a. t, and j. j. quinn (2003). proofs that really count : the art of mathematical association of america. washington dc benjamin, a. t, j. j. quinn, and f. e. su (2000). phased tilings and generalized fibonacci. the fibonacci quarterly, 38(3); 282–288 carlitz, l., r. scoville, and v. e. hoggatt (1972a). fibonacci representations. fibonacci quarterly, 10(1); 1 – 28 carlitz, l., r. scoville, and v. e. hoggatt (1972b). fibonacci representations. fibonacci quarterly, 10(1); 29 – 42 carlitz, l., r. scoville, and v. e. hoggatt (1972c). fibonacci representations of higher order. fibonacci quarterly, 10(1); 71 – 80 carlitz, l., r. scoville, and v. e. hoggatt (1972d). fibonacci representations of higher order. fibonacci quarterly, 10(1); 43 – 70 dunlap, r. a. (2003). the golden ratio and fibonacci numbers. world scienti�c press, singapore frontczak, r. (2018). sums of powers of fibonacci and lucas numbers: a new bottom-up approach. notes on number theory and discrete mathematics, 24(2); 94 –103 koshy, t. (2001). fibonacci and lucas numbers with application. john wiley & sons inc., new york krishna, h. v. (1980). identities of a generalized fibonacci sequence. the fibonacci association, 18; 65 – 66 posamentier, a. s, and i. lehmann (2007). the fabulous fibonacci numbers. prometheus books, new york william, h. c. (1972). fibonacci numbers obtained from pascal’s triangle with generalization. fibonacci quarterly, 10(4); 405 – 412 © 2019 the authors. page 36 of 36 introduction some identities for lucas and gibonacci numbers some identities for lucas number some identities for gibonacci number sum of cubic for lucas and gibonacci numbers conclusions article http://sciencetechindonesia.com article history received: 30 october 2016 received in revised form: 2 january 2017 accepted: 5 march 2017 doi: 10.26554/sti.2017.2.2.37-44 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 37-44 impregnation of bentonite with cellulose as adsorbent of congo red theresa monnica1*, santa octavia ginting1 1department of chemistry sriwijaya, faculty of mathematic and natural sciences, sriwijaya universitym, indralaya, 30622 indonesia *corresponding author : email: monnica.theresa@gmail.com abstract the process of bentonite impregnation with cellulose has been studied. cellulose extracted from rubber wood and clay from natural bentonite was activated. the impregnation process is performed using thiourea as impregnant agent. the impregnation results were characterized by using ft-ir spectrophotometer then the material was used as congo red dye adsorbent. factors affecting the adsorption process were studied by kinetic parameters and thermodynamic parameters. the ftir results indicate the impregnation process was succesfully conducted the characterization by ftir indicated resources of typical absorption of the hydroxyl (oh) and vibrational (-ch) vibration function groups as specific groups of cellulose appearing at wave numbers 3464.15 cm-1 and 2368.59 cm-1 from impregnated material. vibration si-o-si and al-o-si as bentonite-specific strands groups appear at 1465.9 cm-1 and 609.51 cm-1 wavenumbers in the impregnated spectra. the adsorption thermodynamic study showed that the adsorption and adsorption capacity of the cellulose-impregnated bentonite adsorbent reached the optimum point at 50 ° c at 43.47 mol/g and energy of 11.62 kj mol. the optimum enthalpy (δh) of cellulose bentonite was 143.13 kj/mol and the minimum entropy (δs) at concentration of 40 mg/l was 0.207 kj/mol. keywords: bentonite, cellulose, impregnation; adsorption; congo red introduction one of the clay mineral resulting from volcanism is bentonite. the existence of bentonite is very abundant in nature indonesia, cheap, and easily available (mar et.al, 2013). as an inorganic material, bentonite has different capabilities with other inorganic material, which can swell and has a layered structure (barast et.al, 2017). bentonite has been used as adsorbent and methods modifications have also been developed, such as intercalation, insertion and pillarization. one of modification of bentonite clay that has not been done is the impregnation methods. the impregnation is physically solid attachment process with an adsorbent material. impregnation is used to increase the adsorption capacity and selectivity of an adsorbent (pandey, 2017). impregnation generally used as a method for modifying an organic material with other organic material or with inorganic materials. the organic material used as a modified clay material in the form of cellulose. cellulose has many advantages because it is used in various fields such as apparel and fiber, wood and paper, pharmaceutical and cosmetic industries and also for adsorbent of waste water and heavy metals (orlandi et.al, 2017). cellulose, hemicellulose and lignin contained in the wood fiber gum. the presence of cellulose, hemicellulose and lignin made of rubber wood fiber can potentially be used as an absorbent material. fiber is also environmentally friendly because it can be degraded biologically. the existence of abundant wood fiber, easily available and inexpensive because it comes as a byproduct of the wood processing industry (suhas et.al, 2016). the development of textile industry, which grew rapidly results in increased of waste water that enter into water system in the form of dye. congo red dye as an organic substance synthesis is one of the waste products produced by the textile industry. congo red dye are azo group (rn = nr) is red, toxic and difficult to be degraded as a complex chemical structure and the presence of aromatic rings (munagapati and kim, 2017; bharali and deka, 2017). in use as a textile dye in tirth country waste water containing congo red dye not handled well, even dumped directly into the environment. one of the intense use for textile dye is congo red. if congo red substance direct contact to humans it can cause some diseases such as allergies, skin irritation, dermatitis, mutations in the body, it can even cause cancer. removal of congo red has been investigated by adsorption using various adsorbent such as hydrotalcites (said and palapa, 2017), metal organic framework based materials (zhao et.al, 2017), porous materials (lei et.al, 2017), and also zeolites (liu et.al, 2014). impregnation of bentonite was conducted by many researchers for various application. garade et.al (2010) was used dodecatungstophosphoric acid for impregnation of bentonite and material was used as catalyst of hydroxylation of p-cresol. bentonite also impregnated with titanium oxide for degradation of methylene blue (rossetto et.al, 2010). functionalization of bentonite also was achieved by impregnation, which was used nanoparticles as impregnant (amadio et.al, 2017). in this study, impregnation of bentonite with cellulose was conducted. material was used as an adsorbent for congo red dye in aqueous medium. the interaction parameters tested between congo red and adsorbent in the adsorption process were the influence of time, concentration, temperature and ph. in order to determine the residual concentration (mg/l) and the amount of congo red adsorbed (mg/l) adsorbent activated bentonite (control) and bentonite impregnated cellulose were then analyzed using a uv-vis spectrophotometer. © 2017 published under the term of the cc by nc sa 4.0 licence 38 author et al. 2017/sciene & technology indonesia 2 (2) 2017:37-44 experimental section chemicals and instrumentation the materials used in this study are wood fiber (± 60 mesh), hydrochloric acid (hcl), bentonite (al 2 o 3 .4sio 2 .xh 2 o), dye congo red (c 32 h 22 n 6 na 2 o 6 s 2), sulfuric acid (h 2 so 4), sodium hydroxide (naoh), thiourea (h 2 ncsnh 2) and distilled water (h 2 o). the instrumentals were thermometer, hotplate, oven, furnace, horizontal shaker, ftir spectrophotometer (shimadzu prestige-21) and uvvis spectrophotometer (thermo scientific geneysis 20). methods preparation of cellulose fibers from wood dust a total of 100 g of wood fibers soaked into hydrochloric acid (hcl) 0.1m for 3 hours stirred and then filtered, the solid is taken and then rinsed with destilled water, followed by immersion using 0.1 m naoh for 3 hours stirred and then filtered and the solids washed with destilled water until the filtrat water has ph neutral. the process of soaking by hcl and naoh was four times repetition to get cellulose that agrees or approaching standard cellulose characteristics. the residue was dried and then characterized using ftir spectrophotometer and determint of the moisture and ash content. the characterization results were compared to standard cellulose. determination of moisture and ash content of cellulose from wood fiber a total of 1 g of cellulose put in a petri dish that known weight and heated in an oven at 110°c for 5 hours and then weighed until gain constant weight and counted the percent moisture content of cellulose. for determint of the ash containt of the cellulose was heated at 400°c in a furnace for 3 hours. the ash formed then weighed and calculated the weight percent of ash content of cellulose. bentonite activation bentonite preparation procedure was performed according to ozcan (2004). a total of 100 g natural bentonite is heated using the furnace at a temperature of 400 °c for 2 hours and then allowed to stand at room temperature and than followed by acidification process. acidification is done by dissolving 50 g of bentonite into 250 ml of sulfuric acid (h 2 so 4 ) 1 m for 2 hours. the suspension is allowed to stand until the precipitate formed and filtered. furthermore bentonite which has been prepared called bentonite activated. natural bentonite and natural bentonite heated at a temperature of 400 °c and natural bentonite results from acidification using sulfuric acid (h 2 so 4 )were characterized using ftir spectrophotometer. bentonite impregnation with cellulose amount of 2 g of cellulose was added to a mixture of 0.6 m naoh solution and the solution of thiourea 1 m. the mixture was stored at 0 °c for 4 hours to obtain a solution (i), a total amount of 10 g of bentonite is mixed with naoh 46% as much as 16 ml in ice water for 6 hours while stirring with a magnetic stirrer. ice as much as 26 g was added to obtain a solution (ii). the solution (i) and (ii) are mixed and stirred with a magnetic stirrer for 30 minutes and then a few drops of the solution of h 2 so 4 5% evenly to the solid results obtained impregnation and left for 1-2 hours. the solids are washed with distilled water and ready to be used as adsorbent characterized using ftir spectrophotometer. preparation of congo red dye stock solution a total of 1 g congo red dye dissolved in distilled water in a 1 l flask to obtain a concentration of 1000 ppm. preparation of standard solution of congo red the standard solutionof congo red dye prepared by diluting the stock solution into to standard solution with a concentration of 5, 10, 15, 20, 25, 30, 40, and 50 mg/l. effect of adsorption time the amount of of 0.03 g adsorbent of the activated bentonite (control), wood fibers (control) and bentonite impregnated cellulose was added into the 50 ml congo red solution with a concentration of 40 mg/l. before the adsorption process the first measurement of ph of the mixture and adjusted to the initial ph. the adsorption process has taken place at a horizontal shaker at predetermined intervals. the variation of the adsorption time starts at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120 minutes. the adsorbent then separated from the solution using centrifugation and the congo red dye concentration in the solution after interaction was measured using a uv-vis spectrophotometer. the amount of residual concentration (mg/l), the amount of congo red dye adsorbed (mg/l) was calculated using the equation of the calibration curve of standard solution, while the rate of adsorption (k 1 ) is calculated using the equation of langmuir-heinselwood. effects of concentration and temperature adsorption the influence of thermodynamic adsorption congo red dye by activated bentonite (control), cellulose and bentonite extraction results impregnated cellulose is done through a series of experiments with varying concentrations of congo red dye adsorption and temperature. adsorbent activated bentonite (control) of 0:.03 g and 0.03 g of bentonite impregnated cellulose weres mixed with 50 ml of congo red dye (40, 30, 20, 10 and 0 mg/l). while the extraction of cellulose (control) is added to 50 ml of congo red dye at a concentration (25, 20, 15, 10, 5 and 0 mg/l). the adsorbent which has been mixed with the congo red dye measured ph using a ph meter and adjusted to the initial ph congo red dye that has previously been known then the mixture is stirred using a horizontal shaker for 30 minutes at varying temperatures (30, 40, 50, 60 and 70 oc). the mixture is separated, then a solution of congo red dye that has separated from the adsorbent measured absorbance values using a uv-vis spectrophotometer to determine the concentration of residual congo red dye after the adsorption process. the adsorption capacity (b), the adsorption energy (e) can be calculated using the langmuir equation, while the adsorption enthalpy (δh), and the adsorption entropy (δs) can be calculated using thermodynamic equation. results and discussion determination of moisture and ash content of cellulose the moistures and ash content of the wood fiber after the acidification treatment using 0.1 m hydrochloric acid and followed by immersion using 0.1 m sodium hydroxide acidification process and immersion with a base made 4 times and each time the treatment was measured moisture content and ash content contained therein. after going through this process is expected to obtain cellulose that is free of impurities and other macromolecular compounds such as lignin and hemicellulose. unwanted compounds including such impurities will form a salt and water molecules when reacted with hydrochloric acid and sodium hydroxide. the resulting salt has a great solubility in water, so that impurities in the form of monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 39 the salt will be lost during the washing process until a neutral ph. determination of water content is done at a temperature of 110°c using the oven, while determination of ash carried out at a temperature of 400°c using a furnace. results of the determination of moisture content and ash content of cellulose are presented in tables 1. the moistures content as presented in table 1 shows the hydrate water which can be removed by heating 110°c. the water content must be determined in a material because it relates to the use of such materials. in general, the desired moisture content has low water content. it also relates to the retention time of the material to be used in this case is cellulose washing results. if the high water content in the storage cellulose cellulose cannot be done in a longer period of time with limited use anyway. in this study, treatment outcome cellulose has relatively low water content in the range of 1.98 to 6.52% (w/w). acidification and soaking treatment with a base that is repeated causing the water content owned cellulose decline. furthermore, the determination of ash content in the cellulose washing results as presented in table 1. the ash content indicates the content of metal oxides contained in the cellulose washery. metal oxides in cellulose as presented in table 1 is derived from elements of macro and micro nutrients that exist in plants that in this case derived from wood fibers. the more the process of leaching with acid and base will cause a decrease in ash content. the process of soaking with acid and bases as much as 4x produce low ash content which amounted to 0.91% (w/w). results of the determination of moisture content and ash content in the cellulose cannot be the basis of success and purity cellulose extracted from table 1. data cellulose moisture and ash content of the wood fiber washers cellulose water content (% w/w) water content (% w/w) 1x 6.52 6.86 2x 4.85 6.73 3x 3.96 6.00 4x 1.98 0.91 wood fiber and therefore need to proceed with spectroscopic characterization using ft-ir spectrophotometer. cellulose characterization of wood fiber extraction results using ftir spectrophotometer prior to the extraction of cellulose, the first made of wood fiber identification using ft-ir and compared to the ft-ir spectrum of standard cellulose. comparison of ft-ir spectrum of a standard cellulose and cellulose prior to purification is presented in figure 1. shows ft-ir spectra of a standard cellulose showed absorption at 3348.2 cm-1 which is the stretching vibration of the hydroxyl group (oh). wavenumber at 2900.4 cm-1 indicates -ch vibration which is a constituent group of the cellulose structure and reinforced with vibration at wavenumber 1427.32 cm-1 and 1373.32 cm-1.co group which is a carbon chain connecting the cellulose compound is located in the fingerprint region at wave number 1250-1030 cm-1 and a stretching vibration. the wave number 3410.15 cm-1 indicates the presence of hydroxyl (oh), the wave number 2924.09 cm-1 indicates the group -ch reinforced with vibration at wave number 1427.32 cm1,1327.03 cm1 and in the fingerprint region that is at 1250-1050 cm-1 for ether group (-co). in the ft-ir spectra showed similarities with the standard cellulose cellulose before extracted. in the ft-ir spectra of cellulose gum wood still visible tops of unwanted vibration is the wave number 1600-1700 cm-1 that indicates aromatic structure of lignocellulose constituent. therefore necessary advanced separation processes in order to obtain a standard cellulose cellulose approaching. cellulose extraction process aim to separate cellulose from compounds undesirable done by soaking the wood fibers using hydrochloric acid at a concentration of 0.1 m for three hours followed by immersion using sodium hydroxide at a concentration of 0.1 m for three hours. the extraction process is done with 4x repetition. han (manzato et.al, 2017) states that immersion using hcl is used to break the hemicellulose and lignocellulose while naoh solution is used to dissolve the lignin, hemicellulose and other compounds in order to get closer to the characteristics of the cellulose stanfigure 1. ft-ir spectrum of a standard cellulose (a); cellulose before washing with hcl and naoh (b); cellulose 4x washing (c); cellulose 3x washing (d); cellulose 2x washing (e); cellulose 1x washing (f) wavenumber (cm-1) monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 40 dard cellulose. soaking using hcl and naoh be repeated four times in order to obtain an increasingly pure cellulose. cellulose purified identified using a spectrophotometer ft-ir spectra are then compared to standard cellulose. ft-ir spectra measurement results of the standard cellulose, cellulose and cellulose prior purification leaching results are presented in figure 1. its a very clear distinction in the tops of the respective cellulose extraction results. in the ft-ir spectra visible standard cellulose-oh groups have widened while the cellulose absorption separation results have a narrower peak. in the ft-ir spectra of cellulose washery, the ftir spectrum fourth raises oh absorption in the region 3300-3500 cm-1. in the washing process 1x, 2x and 3x has a weak intensity, while for the fourth the peak width appearing with strong intensity. in addition, in figure 1 is seen that the ft-ir spectra of cellulose washing four times has similarities with ft-ir spectra of a standard cellulose especially in the area of 2368.59 cm -1 where the ftir spectra after washing for four times showed a sharp absorption and strong intensity in the region of the wave numbers compared to the ft-ir spectra of washing proceeds 1x, 2x and 3x. in addition to the wave number 2368.59 cm-1 peak seen also similarities that appear at wave number 1100-1600 cm-1 that indicates the co group which is a carbon chain connecting the cellulose compound. the impregnation process is then performed using a bentonite cellulose wood fiber washing the extracted 4x with acids and bases. characterization of natural and activated bentonite using ftir spectrophotometer characterization of functional groups in the natural bentonite, natural bentonite heating at 400 °c and natural bentonite acidified with h 2 so 4 were used ftir spectrophotometer. ft-ir spectrum characterization results are presented in figure 2. the natural bentonite (figure 2a) at wave number 3448.7 cm-1 and 1635.6 cm-1 indicating a vibration of tensile and bending of hoh, explain the water content in the bentonite which acts as interlayer molecules. peak at wave number 3626.1 cm-1 and 910.4 cm-1 indicates the presence of a stretch of al-o-(oh)-al and buckling al-o-(oh)-al indicating the octahedral layers of bentonite. strong intensity at 1033.8 cm-1 seen the peak of the stretch of si-o-si as the tetrahedral layer of bentonite, and vibrational bending si-o-si appears at 470.6 cm-1. peaks appear at 532.3 cm-1 indicate of the vibration of buckling al-o-si and an absorption band that appeared at 686.6 cm-1 indicates vibration of the mineral feldspar, which is associated in mineral bentonite. after characterization of bentonite using ftir spectrophotometer, the next process is the preparation phase is done by heating at a temperature of 400°c and acidification using sulfuric acid (h 2 so 4 ) . natural bentonite heating temperature of 400°c is shown in figure 2b. peaks that appear in the ft-ir spectra of heating results did not show much diferent compared to the vibration generated in the ft-ir spectra of natural bentonite. peak shifting shown in wave number 3695.6 cm-1 as the vibration of the stretch (aloh-al) and the wave number of 694.3 cm-1 that indicates the presence of the mineral feldspar. other absorption bands appear on the same wave numbers with natural bentonite before preparation. the heating process at a temperature of 400°c did not show much shift in wave numbers as an indication of the success of the process, so do the chemical preparation by acidification using sulfuric acid (h 2 so 4 ) . the purpose of acidification with sulfuric acid is to bind to the metals that are small and activates natural bentonite. figure 2c shows the ft-ir spectra of natural bentonite after acidification process. absorption band of the stretch (hoh) and bending (hoh) that appears at wave number 3428.5 cm-1 and 1635.6 indicates a shift. vibration of the stretch (al-oh-al) shifts the wave number 3672.4 cm-1 and buckling (al-oh-al) remained at 910.4 cm-1. in the wave number of 470 cm-1 and 532.3 cm-1are the vibration from buckling (si-o-si) and bending (al-o-si) while the mineral feldspar associated with bentonite absorption at wave number 700 cm-1. declining all transmittance on ft-ir spectra of natural bentonite acidification results followed the changes in the functional groups experienced a shift wave number indicates the success of the preparation process performed on bentonite. characterization of cellulose and impregnated bentonite using ft-ir spectrophotometer perior the impregnation process, cellulose and bentonite were characterized using ft-ir spectrophotometer are presented in figure 3. the specific groups in cellulose extraction results that oh, -ch 2 -o which appears in the spectrum of ft-ir measurement results. -oh group appears at wave number 3387 cm-1 which is oh stretching vibration. the wave number 2908.55 cm-1 indicates figure 2. ft-ir spectrum of natural bentonite (a); natural bentonite heating at 400 °c (b); natural bentonite acidified with h 2 so 4 (c) wavenumber (cm-1) monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 41 vibration of -ch 2 that the structure of cellulose reinforced by vibration at wave number 2368.59 cm-1 and 2137.13 cm-1.stringing group -ch-o2 in which cellulose is a polymer of glucose and fructose appear at wave number 1300-1400 cm-1. the process of acidification on bentonite aims to remove a small cations and simultaneously activates natural bentonite. this is shown in the ft-ir spectrum that presented in figure 3 bentonite which has been acidification with sulfuric acid (h 2 so 4 ) shows the typical absorption bands at 3672.4 cm-1 which is indicates a stretch vibration al-o-(oh)-al, hoh stretch vibration shown in wave number 3425.5 cm-1 and vibrational strain si-o-si at 1041.5 cm-1. vibrations buckling al-o-(oh)-al appear at 910.4 cm-1, hoh bending vibration at 1635.6 cm-1, vibrational bending si-osi appears at wave number 470.6 cm-1 and vibration buckling al-osi appears at 532.3 cm-1. cellulose and activated natural bentonite were modified by impregnation method. the bentonite impregnated with cellulose was made by addition of a mixture of 0.6 m sodium hydroxide solution and 1 m thiourea solution to the cellulose and the addition of sodium hydroxide 46% on activated bentonite, each solution was mixed with a magnetic stirrer for 30 minutes to produce a cellulose impregnation with bentonite. a mixture of 0.6 m sodium hydroxide solution and a solution of 1 m thiourea aims to form a bond between the bentonite with cellulose. the residue was dried and characterized by ft-ir spectrophotometer. ft-ir spectra of cellulose impregnated with bentonite are shown in figure 3 with the important vibrations is summarized in table 2. table 2. comparison of ft-ir spectra of bentonite, cellulose and impregnated bentonite wave numbers (cm-1) functional group bentonite cellulose impregnation 3425.58 3387 3464.15 cellulose-oh 2 9 0 8 . 6 5 2368.59 2931.8 -ch 1 7 3 5 . 9 3 1658.78 1635.64 buckling oh 1041.56 1465.9 tensile si-o-si 532.35 609.51 al-o-si 470.63 432.05 bending si-o-si effect of adsorption time of congo red dye adsorption by activated bentonite, cellulose and impregnated bentonite the adsorption contact time was an important factor in the adsorption process. according to the collision theory, the reaction rate depends on the number of collisions per unit time. the more collisions that occur, the faster the reaction takes place until the reaction reach an equilibrium condition. in this study, the adsorption process of congo red dye by adsorbent bentonite (control), cellulose (controls) and impregnated bentonite performed at a concentration of 40 mg/l congo red with contact time for 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120 minutes. number of congo red dye adsorbed can be seen in figure 4. figure 4 it is shows that the activated bentonite adsorption curve (control) shows an increase in the amount of congo red dye adsorption as the adsorption contact time increases. in the activated bentonite (control) the amount of congo red absorbed in the first 10 minutes was 35.04 mg/l and continued to increase until reaching the optimum time at 120 minutes ie 39.12 mg/l. the congo red dye adsorption process by cellulose indicates that each contact time gives a different effect. at 10 minute contact time absorption is not maximized. this is allegadly because the cellulose active group has not reached its saturation point. the amount of congo red dye absorbed continues to increase until 70 minutes. from the data it can be seen that the optimum contact time required cellulose to absorb congo red dye is 70 minutes with the amount of congo red adsorbed of 2.08 mg/l. the congo red dye adsorption curve by the impregnated bentonite showed in the first 10 minutes the amount of congo red absorbed ie 0.17 mg/l and continued to increase until the 80 minute of contact time 7.08 mg/l and reached the optimum adsorption amount at 100 minutes of contact time ie 8.88 mg/l then decreased at 120 minutes to 3.13 mg/l. after reaching the optimum adsorption with increasing contact time, the adsorbent absorbency will decrease. this is because the active groups on the adsorbent have reached the saturation point of absorption so that the adsorbent no longer able to adsorb the adsorbat. from the data in figure 4 its can be calculated the adsorption rate of congo red dye adsorption on bentonite, cellulose and impregnated bentonite using the langmuir-hinshelwood equation ( )0 1 ln c c t k k c c = + (1) description: c0 = initial concentration of congo red dye (mg/l) figure 3. ft-ir spectrum cellulose after 4x washing with hcl and naoh (a); bentonite acidification (b); cellulose impregnated with bentonite (c) wavenumber (cm-1) monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 42 c = concentration of residual of congo red dye (mg/l) t = adsorption time (min) k 1 = rate of adsorption k = constant adsorption equilibrium the data of congo red dye adsorption rate constant on impregnated bentonite is presented in table 3. table 3 shows the difference of adsorption rate between bentonite, cellulose and impregnated bentonite. the adsorption rate (minute-1) of the impregnated bentonite result is greater than the cellulose adsorption rate. this may occur because the impregnated bentonite is more reactive than the cellulose and the impregnation has more active groups than the cellulose, whereas the activated (control) bentonite has the largest adsorption rate (minutes-1). this can happen because in bentonite there is a chemical adsorption process where the congo red dye is bonded to it surface by forming chemical bonds and homogeneous systems so that the adsorption rate occurs faster. in the adsorbent of congo red dye on cellulose the process that happened in the form of physical adsorption whose strength is weaker than adsorption by adsorbent bentonit. this is because the adsorption process involves a functional group, so the interaction occurs first between the functional groups and causes the adsorption rate to the congo red dye tends to be slower. effects of temperature and initial concentration of congo red dye and the determination of thermodynamic parameters determination of the effect of temperature and initial concentration between congo red dye as adsorbat with adsorbent bentonit (control), cellulose (control) and impregnated bentonite were done by interaction of congo red dye with each adsorbents. the adsorption process was carried out at various temperatures 30, 40, 50, 60, and 70 oc for each adsorbent. the variation of congo red dye initial concentration adsorption by activated (control) and cellulose bentonite adsorbents was carried out at the same concentrations of 5, 10, 15, 20, 25 mg/l, whereas cellulose-impregnated bentonite adsorbents were performed on congo red dye concentration variations 10 , 20, 30, 40 mg/l. the adsorption process were carried out for 30 minutes using a magnetic stirrer. the results of congo red dye interactions with bentonite, cellulose and cellulose impregnated bentonite in figure 4. curve adsorption of congo red dye by activated bentonite (control), cellulose and impregnated bentonite as adsorbents table 3. data of congo red dye adsorption rate constant on impregnated bentonite. adsorbent adsorption rate (minutes-1) bentonite (control) 0.031 impregnated 0.002 cellulose 0.001 table 4. thermodynamic parameters (capacity and adsorption energy) congo red dye adsorption by activated bentonite (control), cellulose extracted (control) and impregnated bentonite. adsorbent t(oc) r2 b (mol/g) e(j/mol) a c t i v a t e d b e n t o n i t e (control) 30 0.967 1000 6,847 40 0.945 1000 5.667 50 0.624 1000 7.65 60 0.979 500 3.042 70 0.854 500 6.424 c e l l u l o s e (control) 30 0.904 37.04 0.35 40 0.996 125 4.82 50 0.935 111.11 4.96 60 0.943 111.11 4.35 70 0.940 100 3.32 impregnated bentonite 30 0.598 6.02 2.42 40 0.294 15.38 8.56 50 0.965 43.47 11.62 60 0.884 18.86 4.59 70 0.951 18.86 0.95 table 5. thermodynamic parameters (enthalpy and entropy) of congo red dye adsorption by activated bentonite (control), cellulose extracted (control) and cellulose impregnated bentonite adsorbent c o r2 δh (kj/mol) δs (kj/mol) activated bentonite (control) 5 0.816 77.51 0.258 10 0.974 7.751 0.032 15 0.997 2.639 0.014 20 0.919 51.55 0.171 25 0.903 56.56 0.186 cellulose (control) 5 0.933 112.44 0.321 10 0.945 48.88 0.134 15 0.996 18.922 0.048 20 0.983 10.09 0.018 25 1.000 22.697 0.055 cellulose impregnated bentonite 10 0.912 143.13 0.424 20 0.938 107.26 0.309 30 0.909 34.037 0.99 40 0.950 75.03 0.207 figure 5. effect of congo red concentration and temperatures on adsorption of congo red dye on the activated bentonite monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 43 various temperature and initial concentration can be seen in figure 5. the adsorption process at various temperature and initial concentration of the congo red dye shows in figure 5 the change in the amount of congo red dyes that can be absorbed by the activated bentonite adsorbent (control). the curve shows that the greater the temperature and the congo red concentration, the greater the amount of the congo red dye adsorbed by bentonite (activated). the amount of optimum congo red dye adsorbed by bentonite was seen at 70 °c and 25 mg/l concentration with the amount of 23.07 mg/l. seen at some points, there is a point that coincide at the concentration of congo red 5 mg/l and 10 mg/l. this is because the amount of congo red absorbed at these concentrations does not show too large a difference. in the cellulose adsorbent of wood fibers (controls) presented in figure 6 shows that as the temperature and concentration added increased the amount of congo red adsorbed is less significant. the improvement occurs at temperature 40 oc, its seen that the higher initial concentration and increased temperature the more the amount of congo red dye adsorbed. this causes the cellulose as an adsorbent to be applied at that temperature. while at high temperatures cellulose cannot absorb well is possible because the functional groups on cellulose damaged by the heating process. in contrast to the adsorbent of activated bentonite (control) and cellulose (control), cellulose impregnated bentonite in figure. 7 shows the amount of adsorbate congo red dye were adsorbed at high temperature, seen at temperatures of 50, 60 and 70 °c there is a point coinciding with concentrations of 30 mg/l. figure 7 shows that there is not much difference in the amount of congo red absorbed in various initial concentration. while at concentrations of 40 mg/l with various temperatures, there was a decrease in the amount of congo red dyes absorbed. this is because the large particle size of the congo red dye cannot be absorbed by the cellulose-impregnated bentonite adsorbent. thermodynamic parameters were determined by looking for the values of adsorption capacity (b), adsorption energy (e), enthalpy (δh) and entropy (δs) of the adsorption process. the amount of adsorbed red congo (mg/l) at the various temperature (oc) can be calculated for some predetermined concentrations. the calculation data of adsorption capacity (b) and adsorption energy (e) were using equation 2. 1c c m bk b= + (2) were the value of adsorption capacity (b) can be calculated using the equation as the slope and intercept values of the congo red residual concentration (c) as the x-axis to cr eq / n as the y-axis. the adsorption capacity data (b) is presented in table 4. table 4 shows that the value of adsorption capacity (b) for each adsorbent is different. in the activated bentonite adsorbent, the largest adsorption capacity is seen at temperatures of 30 ° c, 40 ° c and 50 ° c, at optimum cellulose (control) adsorbent capacity at temperatures of 50 ° c and 60 ° c. whereas in impregnated bentonite adsorbents, the largest capacity was seen at 50 ° c at 43.47 mol/g. after obtaining the value of adsorption capacity (b), then the value of adsorption energy (e) in each adsorbent is determined by using the constant value obtained from the equation 2. the adsorption energy (e) was calculated using equation 3. e=-rt ln k (3) were; k = equilibrium constant e = energy adsorption (kj/mol) r = constant t = temperature (k) the adsorption energy presented in table 5 shows the largest adsorption energy occurred at 50 °c ie 7.65 kj/mol for bentonite and 4.96 kj/mol for cellulose adsorbent (control). the modified adsorbent has the largest adsorption energy compared with the bentonite and the cellulose as control adsorbent. the cellulose impregnated bentonite has optimum adsorption energy at 50 oc i.e. 11.62 kj/mol. the other congo red thermodynamic adsorption parameters, such as enthalpy (δh) and entropy (δs) can be calculated as slope and intercept values of 1/t as the x-axis to ln kd as the y-axis as shown in equation 4 and the amounts of enthalpy value (δh), entropy (δs) are presented in table 5. ln d h s k rt r ∆ ∆ = − + (4) were; kd = distribution coefficient of adsorbate (qe) δh = enthalpy δs = entropy r = constant t = temperatures the activated bentonite adsorbent (control) has the largest enthalpy value at a concentration of 5 mg/l ie. 77.51 kj. at a temfigure 6. effect of congo red concentration and temperature on cellulose (control) figure 7. effect of congo red dye initial concentration and temperature on cellulose impregnated bentonite adsorbent monnica et al. 2017/science & technology indonesia 2 (2) 2017:37-44 © 2017 published under the term of the cc by nc sa 4.0 licence 44 perature of 10 mg/l and 15 mg/l decreased and then again increased at a temperature of 20 mg/l and 25 mg/l. the enthalpy value on the optimum cellulose (control) adsorbent at concentration 5 mg/l was 112.44 kj/mol then again decreased. cellulose impregnated bentonite adsorbent has the greatest enthalpy value compared with bentonit (control) and cellulose (control) of 143.13 kj/mol at initial concentration ie. 10 mg/l. activated bentonit adsorbent (control) has the largest entropy at concentration 5 mg/l that is equal to 0.26 kj/mol as well as cellulose adsorbent (control) biggest entropy value happened at concentration 5 mg/l that is equal to 0.321 kj/mol. in bentonit adsorbent impregnated cellulose the largest entropy value at congo red 30 mg / l concentration of 0.99 kj/mol. conclusion the ft-ir spectral shows that impregnated bentonite was successful, as seen from the specific fungtional groups of bentonite and cellulose that appear on the impregnation result. the fungtional groups that are hydroxyl (oh) and vibrational (-ch) vibrations as specific groups of cellulose appear in wave numbers 3464.15 cm-1 and 2368.59 cm-1 in the impregnated spectra. si-o-si and alo-si strands as bentonite-specific groups appear at 1465.9 cm-1 and 609.51 cm-1 wave numbers in the impregnated spectra. the cellulose impregnated bentonite adsorbent reached the optimum adsorption process at minute 120, the extracted cellulose (control) reached optimum condition at minute 90 while the cellulose impregnated bentonite adsorbent reached optimum adsorption process at minute 100 i.e. 8.88 mg/l. the adsorption enthalpy of adsorption of cellulose-impregnated bentonite has the greatest amount compared to the control adsorbent of 11.62 kj/mol for adsorption energy and 143.13 kj for reaction enthalpy. references amadio. t.d.m., hotza. d., rodrigues neto. j.b., blosi. m., costa. a.l., dondi. m. 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(2010). bentonite impregnated with tio 2 for photodegradation of methylene blue. applied clay science, 48, 602-606. said. m., palapa. n.r. (2017). adsorption of congo red using mg/al hydrotalcite. science and technology indonesia, 2017, 17-21. suhas., gupta. v.k., carrott. p.j.m., singh. r., chaudhary. m., kushwaha. s. (2016). cellulose: a review as natural, modified and activated carbon adsorbent. bioresource technology, 216, 1066-1076. zhao. s., chen. d., wei. f., chen. n., liang. z., luo. y. (2017). removal of congo red dye from aqueous solution with nickel-based metal-organic framework/graphene oxide composites prepared by ultrasonic wave-assisted ball milling. ultrasonics sonochemistry, 39, 845-852. _goback title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 research paper formulation of ionic-gelation submicron particles loading extract papaya leaves (carica papaya l.) with lactic acid isolates mardiyanto1*, budi untari1, najma annuria fithri1, sofia sandi2 zahrul mawaddah1 1department of pharmacy faculty of mathematics and natural science, sriwijaya university 2department of animal food, faculty of agriculture, sriwijaya university *corresponding author: mardiyantounsri@gmail.com abstract a study regarding ionic-gelation submicron particle of papaya leaves (carica papaya l.) extract with lactic acid of weeds potentially for antidiarrhea has been conducted. preparation of papaya leaves ethanolic extract and lactic acid isolate into particles was done by ionic gelation method. this study aimed to determine: the major compound of extract, the total quercertine of extract, the percent value of encapsulation e�iciency of the optimum formula which was varied by (caoh)2 of the three formulas, and physical properties of particles. formula 1 was using (caoh)2 of 12.5 gram; formula 2 (caoh)2 of 17,5 gram; formula 3 (caoh)2 of 22.5 gram. the results showed formula 1 as the optimum formula that has the highest %ee. the average %ee values of f1; f2; f3 respectively were 80,82%; 80,41%; 80,31%. the results of particle characterization using the psa in the optimum formula produced particle size values with an average of 253.6 nm, pdi of 0.218, and zeta potential +8 mv respectively. keywords ionic-gelation, submicron-particles, carica papaya l., lactic acid isolates received: 16 june 2019, accepted: 20 july 2019 https://doi.org/10.26554/sti.2019.4.3.77-81 1. introduction swamp forages has been a major wild weeds in swamp area (li et al., 2015). swamp forages can be utilized in the process of production which results in the formation of organic acid as a metabolite by lactic acid bacteria. these bacteria convert carbohydrates into lactic acid. isolate of lactic acid is a probiotic which has the functions as a growth promoter for normal �ora in the human intestine (moorthy et al., 2015). forages of swamp are also found in indralaya (south sumatra province) indonesia. kumpai weed (hymenache acutigluma) is one of the. lactic acid isolate can be used in antidiarrheal therapy because it has the function of feeding the normal �ora in the intestine to compete with the escherichia coli as the pathogenic bacteria that causes diarrhea. alternative natural ingredients that can be combined with lactic acid isolates are papaya leaves (carica papaya l.) which have antibacterial activity to inhibit the growth of pathogenic bacteria (baskaran et al., 2012). diarrhea is defecation with liquid or semi-liquid stool and more than usual fecal water content (more than 200g or 200ml / 24h). cotrimoxazole is the most important antibiotic in treating diarrheal diseases. the over-use of antibiotics can lead to resistance (bow et al., 1998) such as the resistance pattern that shown of escherichia coli (as much as 95%) to cotrimoxazole, so it is relevant reason to use alternatives from natural ingredients without resistances such as leaf extract of carica papaya (vale et al., 2015). the treatment of speci�c diarrhea caused by bacterial infection is expected to provide the maximum therapeutic e�ect(shen et al., 2018) to pathogenic bacteria by using the new dosage form (jyoti et al., 2019) in the form of particles (chandrasekaran et al., 2016) which encapsulated the extract properly. this study aims to elevate the potential of papaya leaves combined with lactic acid isolates as antidiarrheal herbal medicines formulated in the form of particles for development of new dosage form for oral administration (banala et al., 2015). the formulation of antidiarheal herbal medicine can reduce the use of synthetic drugs for the treatment of diarrhea. the in-vivo test was performed on wistar strain male rats which induced by escherichia coli. 2. experimental section 2.1 materials the materials used in this study were: extract of papaya leaves (carica papaya l.) and lactic acid isolate from department of pharmacy sriwijaya university, ethanol 96% (merck®), quercetin (sigma-aldrich®), escherichia coli, chitosan (sigma-aldrich®), sodium alginate (sigma-aldrich®), citric acid (sigma-aldrich®), https://doi.org/10.26554/sti.2019.4.3.77-81 mardiyanto et. al. science and technology indonesia, 4 (2019) 77-81 figure 1. papaya (carica papaya l) leaves figure 2. structure of quercertine and the position of chromophore and auxocrome side calcium chloride (sigma-aldrich®), nacmc (sigma-aldrich®), sodium hydroxide (merck®) and aquadest. 2.2 methods 2.2.1 extraction of papaya leaves papaya leaves were obtained at inderalaya, south sumatra which were taken from dark green leaves, then washed with running water. the drying process was protected from direct sunlight exposure for 14 days. leaves were pollinated using a blender. the powder was sifted so that the obtained simplicia powder was appropriate to be extracted. preparation of extracts was done by maceration method. 3 kg of papaya leaves powder were dissolved in 96% ethanol with solvent replacement every 48 hours for 5 days. after that, the residue was �ltered. then the residue was macerated again with ethanol 96% for 2 days and �ltered as the mixing �ltrate. finally the �ltrates were mixed and then evaporated with a rotary evaporator at 60°c to obtain a thick extract. 2.2.2 identi�cation of flavonoid compounds the 1 g thick papaya leaf extract (carica papaya l.) is included in the test tube. 5 ml of ethanol is added, then heated for 5 minutes. 0.2 mg of mg powder and 2 drops of concentrated hcl are added to the tube. another method can be done by adding 2 drops of 10% naoh. if it produces yellow, orange and red it indicates �avonoid. this work to �t the previous research regarding identi�cation of papaya extract by gogna et al. (2015). figure 3. illustration of combining ionic polymer to form submicron particle figure 4. the size and the distribution of submicron particles 2.2.3 determination of moisture content determination of water content was carried out using the gravimetric method. 1 g of extract is weighed carefully in a container that has been anchored. the extract was dried at 105°c for 30 minutes and weighed. drying is continued until constant weight. 2.2.4 formula the papaya ethanol extract nanoparticle formula with lactic acid isolates was shown in table 1. variation of the formula in this study was f1 isolates of lactic acid was added ca(oh)2 as much as 12.5 grams, f2 isolates of lactic acid + ca(oh)2 as much as 17.5 grams and f3 of 22.5 grams of lactic acid was added ca(oh)2 isolates were used as much as 10 mg, chitosan as much as 35 mg, sodium alginate 50 mg and calcium chloride 0.018m. the di�erence in this formula is the concentration of ca(oh)2 which is mixed into lactic acid isolates to obtain the optimum formula. 2.2.5 preparation of gelation-ionic submicron particles citric acid of 50 mg was dissolved in 10 ml aquadest and then 3 ml of citric acid solution was pippeted and mixed into 1000 mg extract of papaya leaves as mass 1. the remaining 7 ml citric acid solution was mixed with 35 mg chitosan, sodium alginate of 50 mg was dissolved into 10 ml hot water, then solution was stirred until homogeneous. chitosan was dissolved in 7 ml citric acid solution then it was mixed into 10 ml sodium alginate solution for each formula as mass 2. mass 1 and mass 2 were © 2019 the authors. page 78 of 81 mardiyanto et. al. science and technology indonesia, 4 (2019) 77-81 table 1. the formula of ionic-gelation submicron particles materials amount of materials in formula f1 f2 f3 extract papaya leaves (mg) 1000 1000 1000 isolat lactic acid 8,24×107cfu/ml (mg) 10 10 10 ca(oh)2 (g) 12.5 17.5 22.5 citric acid (mg/ml) 50 50 50 chitosan (mg) 35 35 35 alginate sodium (mg) 50 50 50 cacl2 0,018m (mg) 9 9 9 mixed drop by drop on the stiring condition using a magnetic stirrer. the mixing process was allowed to run at a speed of 750 rpm for 1 hour. pre-particles were formed and then stored at chill temperature. a solution of 9 mg of calcium chloride in 10 ml of aquadest was mixed for the three formulas. lactic acid+ca(oh)2 isolate of 10 mg for each formula. 2.2.6 determination of total quercertine and %encapsulation this process was started for preparation a calibration curve with a concentration of 2,4,6,8,10 ppm of quercertine at the wavelength that has been obtained. preparations was used to calculate percent e�ciency of encapsulation by separating preparations using centrifuges. separate supernatants from each formula were added 0.1 ml of 10% sodium acetate and 0.1 ml of alcl3 10% were measured at the maximum wavelength at 436 nm using a uv-vis spectrophotometer to obtain the absorbance value. the absorbance results are made in the form of a calibration curve in the regression equation (y = a + bx) with a value of r ≥ 0.990. 2.2.7 characterization of submicron particles the potential diameter, polydispersity index (pdi), and zeta were measured using a particles size analysis (psa) with the dynamic light scattering (dls) method. the particles suspension was taken as much as 50 �l and diluted 100 times to 5 ml using distilled water, then 50 �l was taken and put into the cuvette psa, then the monochromatic light was �red by the instrument, the light was refracted at 90° and 173° and the detector would capture the results refraction of light to produce potential zeta data, while the results of scattering light at an angle of 90° will be captured by the detector so that it had diameter data and particle distribution (fithri et al., 2017). 3. results and discussion 3.1 simplicia determination determination of samples was done at the andalas university herbarium (you), biology department, fmipa andalas university, limau manih campus, padang, west sumatra. the results of the determination showed that the sample used in the study was pepaya as shown in figure 1 with the namely pepaya (carica papaya l.) from the caricaceae family. 3.2 extraction of papaya leaves the extraction process of papaya leaves was done by maceration using 96% ethanol. maseration is done by inserting dry simplicia into a dark glass vessel to avoid interaction with light, then soaking while occasionally stirring, after 5 days of silence then �ltered using a funnel coated with �lter paper so that i get the �ltrate i and residue. the residue was macerated with the solvent which was just left for 48 hours then �ltered again using �lter paper placed on top of the glass funnel and �ltrate ii was obtained. the �rst and second �ltrates that were produced were then evaporated using a rotary evaporator until a thick extract was obtained. thick extract is obtained as much as 85.56 g and has a yield value of 4.278%. 3.3 identi�cation of flavonoid compounds the identi�cation of compounds carried out on the ethanol extract of papaya leaves is a test of �avonoids and the structure was represented in figure 2. the compound has an antibacterial activity that can kill pathogenic bacteria that cause diarrhea. the ethanol extract of papaya leaves added magnesium reagent showed positive results with the formation of brownish red color due to magnesium and hcl reacting with �avonoid compounds through the reduction of benzopiron nuclei in the structure of �avonoids with 10% naoh reagent showed positive results with the formation of red brick colour, due to �avonoids including the phenolic compounds reacted with bases to produce a colour change. 3.4 determination of moisture content determination of water content was carried out on ethanol extract of papaya leaves with the aim to determine the residual moisture content after the drying or thickening process. the high water content in the extract can also a�ect the quality of preparations that function as antibacterial so that the water content of the extract must be in accordance with the standards set by materia medika indonesia which was < 10% which cannot be overgrown with microbes. the value of water content of the ethanol extract of papaya leaves obtained was 9.09%. 3.5 determination of total quercertine and %ee determination of percent encapsulation e�ciency begins with making a calibration curve that obtains a linear regression equa© 2019 the authors. page 79 of 81 mardiyanto et. al. science and technology indonesia, 4 (2019) 77-81 tion y = 0.079x 0.094 with an r value of 0.999. percentage of encapsulation e�ciency (% ee) as shown in table 2 was calculated by using a formula to determine the levels of ethanolic extract of papaya leaves in an encapsulated formula. the higher the% ee value, the more extracts encapsulated in the polymer were used. the value of the %ee were then analyzed using spss 22. the results of the analysis can be seen as the data were normally distributed or can be analyzed using the normality test. based on the analysis of the normality test the %ee obtained a signi�cance value of > 0.05 using the shapiro-wilk method which indicates that the value did not have a signi�cant di�erence meaning the data is normally distributed. the one way anova method can be used for further step. the result of the analysis had a no signi�cance value of anova test of (p > 0.05). the value of %ee were in same level. nevertheless, the highest value was shown by f1. the optimum formula was represented by f 1 which had the smallest concentration of ca(oh)2 compared to formula 2 and 3. high levels of ca2+ ions in the preparation due to crystalline alkaline ca(oh)2 isolates in the preparation cause shrinkage in the size of the submicron particles the dimensions of the submicron particle preparation are reduced and only a few extracts can be encapsulated by alginate polymers. table 2. results of %ee calculation formula (f) %ee±sd 1 80,82% ±0,0088 2 80,41% ±0,0342 3 80,31% ±0,0310 3.6 evaluation and characterization of submicron particles particles were formed by using chitosan, alginate, and ion calcium that was illustrated in figure 3. in order to know the character of particles, the evaluation of physical properties was the main work which was to be conducted. particle size distribution is important parameter (banala et al., 2015) because it a�ects the ability of penetration, stability, and the potential for drug e�ects and safety. the smaller the pdi value, the better. this is because the smaller this shows that the particles are more uniform (rawat et al., 2006). the results of the analysis of diameter measurements and particle distribution in the optimum formula (as shown in figure 4) was 253.6 nm and the optimum formula shows results that enter the size range 200 500 nm. 4. conclusions based on the research that has been done, conclusions can be drawn as follows: 1. the value of% ee produced in formulas 1, 2 and 3 is 80.82% ± 0.0088; 80.41% ± 0.0342; and 80.31% ± 0.0310 indicated that the f1 was an optimum formula. 2. the results of particle characterization using the psa in the optimum formula produced particle size values with an average 253.6 nm, pdi 0.218, and zeta potential +8 mv respectively. 5. acknowledgement an expression of the gratitude are towards to sriwijaya university for kompetitif research grant 2019 with allocation of pnbp funding that made this research regarding formulation for new product was possible as well as the authors deliver the thank to laboratory of nanofabrication of indonesia islamic university (uii) yogyakarta and particles laboratory of ugm for all the helps provided to complete this research. references banala, r., v. nagati, and p. karnati (2015). green synthesis and characterization of carica papaya leaf extract coated silver nanoparticles through x-ray di�raction, electron microscopy and evaluation of bactericidal properties. saudi j of bio sci, 22(5); 637–644 baskaran, c., r. b.v, s. velu, and k. kumaran (2012). the e�cacy of carica papaya leaf extract on some bacterial and a fungal strain by well di�usion method. asian paci�c j of tropical dis, 2(2); 658–662 bow, e., e. rayner, and t. louie (1998). comparison of nor�oxacin with cotrimoxazole for infection prophylaxis in acute leukemia: the trade-o� for reduced gram-negative sepsis. the american j of medicine, 84(5); 847–854 chandrasekaran, r., s. gnanasekar, p. seetharaman, and r. keppanan (2016). formulation of carica papaya latexfunctionalized silver nanoparticles for its improved antibacterial and anticancer applications. journal of molecular liquids, 219; 232–238 fithri, n. a., , m. mardiyanto, r. p. novita, and v. andrean (2017). furosemide self nano emulsifying drug delivery system (snedds) formulation comprising of capryol-90, polysorbate80, and peg-400 with simplex-lattice-design. science and technology indonesia, 2(4); 85–88 gogna, n., n. hamid, and k. dorai (2015). metabolomic pro�ling of the phytomedicinal constituents of carica papaya l. leaves and seeds by 1h nmr spectroscopy and multivariate statistical analysis. journal of pharmaceutical and biomedical analysis, 115; 74–85 jyoti, a., v. kumar, and p. gopinath (2019). carica papaya loaded poly (vinyl alcohol)-gelatin nano�brous sca�old for potential application in wound dressing. materials science and engineering, 103; 109–114 li, x., x. luo, c. si, n. wang, h. zhou, and j. he (2015). antibacterial active compounds from hypericum ascyron l. induce bacterial cell death through apoptosis pathway. eur j med chem, 96(26); 436–444 moorthy, s. k., c. ashok, k. r. venkateswara, and c. viswanathan (2015). synthesis and characterization of mgo nanoparticles by neem leaves through green method. materials today, 2(9); 4360–4368 rawat, m., s. singh, and y. saraf (2006). nanocarriers: promising vehicle for bioactive drugs. biol pharm bull, 29(9); 1790 – 1798 shen, w., j. han, p. yan, and y. zheng (2018). soluble expression of biologically active methionine sulfoxide reductase b1 (pam© 2019 the authors. page 80 of 81 mardiyanto et. al. science and technology indonesia, 4 (2019) 77-81 srb1) from carica papaya in escherichia coli and isolation of its protein targets. protein expression and puri�cation, 146; 17–22 vale, a., j. santos, a. melin, v. peixoto, n. brito, z. beatrim, and p. oliveira (2015). phytochemical composition and antimicrobial properties of four varieties of brassica oleracea sprouts. food control, 55; 248–256 © 2019 the authors. page 81 of 81 introduction experimental section materials methods extraction of papaya leaves identification of flavonoid compounds determination of moisture content formula preparation of gelation-ionic submicron particles determination of total quercertine and %encapsulation characterization of submicron particles results and discussion simplicia determination extraction of papaya leaves identification of flavonoid compounds determination of moisture content determination of total quercertine and %ee evaluation and characterization of submicron particles conclusions acknowledgement science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 22-24 article http://sciencetechindonesia.com @2017 published under the terms of the cc by nc sa 4.0 license 22 preparation, characterization, and thermal stability of b2o3-sio2 winda fitriana1*, aldes lesbani1 1department of chemistry, faculty of mathematic and natural science, sriwijaya university *corresponding author email: winda.fitriana@rocketmail.com abstract preparation of b2o3-sio2 compound by inorganic synthesis was carried out. b2o3-sio2 was characterized by ft-ir spectrophotometer, analysis of crystallinity by xrd, and test of acidity. b2o3-sio2 was also tested by thermal stability with temperature range at 300-700 ⁰c. the results showed that the ft-ir spectrum of b2o3-sio2 has some vibrations of b-o, si-o-si, si-o-b stretching, and si-o-b bending at 1442.8 cm-1, 779.2 cm-1, 925.8 cm-1, and 648.1 cm-1. the x-ray diffraction pattern results showed that the analysis of b2o3-sio2 has high crystallinity with two peaks diffraction identified at 26.6⁰ and 20.9⁰. the thermal stability test of b2o3-sio2 showed that b2o3-sio2 has high thermal stability with temperature range at 300-700 ⁰c. the results showed that the acidity analysis of b2o3-sio2 has potential number 122.71 mv so that indicated b2o3-sio2 was high acidity. keywords : boric oxide, silica dioxide, boric silica, b2o3-sio2 introduction the development of materials such as inorganic materials and hybrid organic inorganic materials is intriguing field as this decade due to applications of these materials for sensor, catalyst, ion exchange, membrane, and also for medical as drugs or agent transfer drugs. the development of these materials can be conducted using physical and chemical processes such as grafting (chrouda et.al, 2015), sol-gel (mcfarland and opila, 2016), impregnation (dhamodaran and gnanaharan, 2007), support compound (sari m a and situngkir, 2016), and chemical reaction. in the chemical reaction, formation of chemical bonding is important in order to form stable novel compounds. chemical reaction sometime involves high temperature and pressure thus this method is sometime omitted due to special reactor is required. in physical method such as impregnation and support method, electrostatic interaction, van der walls, or other physical interaction is formed on materials. in recent years, support materials on inorganic matric is increased sharply. inorganic substances such as boron compounds and its derivatives is interesting materials to develop due to high acidity resulted from non-bonding orbital of boron. boron is found as various compounds in the nature such as boric acid and has been applied as catalyst (kumar et.al, 2014). boric acid has low thermal stability and the application of these compound in various field is still rare. to increase application of that compound thus modification of boric acid is vital. on the other sides, silica compounds such as silica oxide are frequently used in various application such as chromatography for separation and for polymer materials. silica oxide can be used also as support material for inorganic matric (jal, et.al 2004). thus in this research silica oxide is used as support of boric article history received: 21 august 2016 accepted: 30 november 2016 doi: 10.26554/sti.2017.2.1.22-24 compound. the final goal of this research is to obtain inorganic material with high acidity and stability under high temperature. high temperature stable material is needed for many applications such as catalyst and thin film (moon et.al, 2004). the supported material is characterized using x-ray analysis, ftir spectrophotometer, and acidity analysis by potentiometric titration. experimental section chemical with p.a. grade was used in this research from merck such as boric acid, silica dioxide, acetonitrile, nbutylamine, ammonia, and buffer ph 4,7, and 10. characterization was conducted using shimadzu ftir prestige21 with kbr disc, x-ray shimadzu lab x type-6000 and the data was acquired over 0-90 deg. the acidity was analyzed by potentiometric titration using n-butylamine. preparation of b2o3-sio2 boric acid (0.16 g) was dissolved with 30 ml water. the solution was stirring and heating at 80 oc for 10 minutes. silica oxide (1.46 g) was added into the solution. the mixtures were refluxed for 5 hours at 90 oc. the mixtures was concentrated by vacuum to obtain white bulky solid. the solid material was heated at 110 oc for three days to form b2o3-sio2. characterization of b2o3-sio2 was conducted using ftir and x-ray analyses. thermal stability test thermal stability test was conducted using muffle furnace and sample was heated for 3 hours at 400-700 oc. the material after heating process was analyzed by x-ray analysis and acidity measurement. results and discussion material b2o3-sio2 was prepared via inorganic synthetic method without functional group protection. the objectives of this preparation is to obtain material with high acidity and high fitriana et al. / science and technology indonesia 2(1) 2017:22-24 @2017 published under the terms of the cc by nc sa 4.0 license 23 stability under high temperature. material b2o3-sio2 after synthesis was characterized using ftir spectroscopy and ftir spectrum is shown in figure 1. figure 1. ftir spectra of b2o3-sio2. ftir spectrum of b2o3-sio2 has vibration at wavenumber 3434 cm-1 (si-oh), and 3227 cm-1 (b-oh). stretching vibration of si-o-si is appeared at wavenumber 1091-800 cm-1 (arkles, 1987). vibration peaks at 927 cm-1 and 649 cm-1 are assigned as bending and stretching of si-o-b and 1435 cm-1 is assigned as stretching of b-o. identification of b2o3-sio2 is continued using x-ray analysis. the xrd powder pattern of b2o3-sio2 is shown in figure 2. figure 2. xrd powder pattern of b2o3-sio2. compound b2o3 has diffraction at 2 value 26-27 deg and compound sio2 has diffraction at 2 value 20-22 deg. figure 2 show the diffraction at 2 value 20 deg, 26 deg, and 29 deg, which is attributed to diffraction of b2o3-sio2 (osiglio et.al, 2017). there is small diffraction at 2 value 15 deg. probably do to interaction of b2o3-sio2 and that diffraction indicated that material b2o3-sio2 has high crystallinity. the properties of b2o3-sio2 was studied by thermal stability test and acidity measurement. the thermal stability test was conducted at 400-700 oc and the material was characterized using x-ray analysis as shown in figure 3. diffraction patterns of xrd in figure 3 showed that material b2o3-sio2 has high stability under high temperature. the pattern is almost similar each other after heating process. the patterns in figure 3 is also fit with pattern in figure 2. that means structure material b2o3-sio2 almost unchanged with increasing temperature. the acidity material b2o3-sio2 and boric acid was tested using potentiometric titration as shown in figure 4. the titration curve at figure 4 showed that boric acid has potential 57.17 mv and b2o3-sio2 has potential 122.71 mv. that results showed that material b2o3-sio2 has high acidity than boric acid. thus material b2o3-sio2 is candidate for acid catalyst material. figure 3. xrd powder patterns of b2o3-sio2 at various temperatures (a = 300 ⁰c, b = 400 ⁰c, c = 500 ⁰c, d = 600 ⁰c, e = 700 ⁰c). figure 4. potentiometric titration curve of boric acid (a) and b2o3-sio2 (b). -40 -20 0 20 40 60 80 0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 2 e ( m v ) volume n-butilamin (ml) -40 -20 0 20 40 60 80 100 120 140 00,10,20,30,40,50,60,70,80,911,11,21,31,41,51,61,71,81,922,1 e ( m v ) volume n-butilamin (ml) fitriana et al. / science and technology indonesia 2(1) 2017:22-24 @2017 published under the terms of the cc by nc sa 4.0 license 24 conclusion material b2o3-sio2 was successfully synthesized with high crystallinity. this compound also has thermal stability and high lewis acidity, which can be used as effective acid catalyst. references arkles, b. 1987. infrared analysis of organosilicon compounds : spectra-structure correlations. laboratory for materials, inc. burnt hills, new york. chrouda, a., sbartai, a., baraket, a., renaud, l., maaref, a., jaffrezic-renault, n. 2015. an aptasensor for ochratoxin a based on grafting of polyethylene glycol on boron-doped diamond microcell. analytical biocehemistry, 488, 36-44. dhamodaran, t.l., gnanaharan, r. 2007. boron impregnation treatment of eucalyptus grandis wood. bioresource technology, 98(11), 2240-2242. jal, p. k., s. patel, and b. k. mishra. 2004. chemical modification of silica surface by immobilization of functional groups for extractive concentration of metal ions. talanta, 62, 1005-1028. kumar, v., chitra s., upendra s., praveen k. v., bikram s., and neeraj k. 2014. silica-supported boric acid catalyzed synthesis of dihydropyrimidin-2-ones, bis(indolyl)methanes, esters, and amides. indian journal of chemistry, 53, 1, 83-89. mcfarland, b., opila, e.j. 2016. sol-gel derived borosilicate glases and thin film coatings on sic substances: boron loss and carbon retention duet processing and heat treatment. journal of non-crystalline solids, 449, 59-69. moon, o. m., b. c. kang, s. b. lee, and j. h. boo. 2004. temperature effect on structural properties of boron oxide thin film deposited by mocvd method. thin solid films, 164-169. osiglio, l., sathicq, g., pizzio, l., romanelli, g., blanco, m. 2017. preaparation of acetates catalyzed by boric acid and/or tungstophosphoric acid-modified zirconia obtained employing polyethylene glycols as pore-forming agents. journal of molecular catalysis a: chemical, 426, 88-96. sari ma, y., situngkir, m.d. 2016. synthesis, characterization, and thermal stability of k8[siw11o39]nh2o/sio2. science and technology indonesia, 1(1), 8-16. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 2, april 2021 research paper heuristic approach for robust counterpart open capacitated vehicle routing problem with time windows evi yuliza1, fitri maya puspita1*, siti suzlin supadi2 1mathematics department, faculty of mathematics and natural science, university of sriwijaya, south sumatera, indonesia 2institute of mathematical sciences, faculty of science, university of malaya, malaysia *corresponding author: fitrimayapuspita@unsri.ac.id abstract garbage is one of the environmental problems. the process of transporting garbage sometimes occurs delays such as congestion and engine failure. robust optimization model called a robust counterpart open capacitated vehicle routing problem (rcocvrp) with time windows was formulated to get over this delays. this model has formulated with the limitation of vehicle capacity and time windows with an uncertainty of waste volume and travel time. the rcocvrp model with time windows is solved by a heuristic approach. the heuristic approach used to solve the rcocvrp model with time windows uses the nearest neighbor and the cheapest insertion heuristic algorithm. the rcocvrp with time windows model is implemented on the problem of transporting waste in sako sub-district. the solutions of these two heuristic approaches are compared and analyzed. the rcocvrp model with time windows to optimize the route problems of waste transport vehicles that is solved using the cheapest insertion heuristics algorithm is more e�ective than the nearest neighbor method. keywords optimization robust, counterpart open capacitated vehicle routing problem, time windows, nearest neighbour algorithm, cheapest insertion heuristic algorithm received: 14 november 2020, accepted: 23 march 2021 https://doi.org/10.26554/sti.2021.6.2.53-57 1. introduction garbage is one of the environmental problems. to solve this environmental problem, the department of cleanliness and the environment carries out waste transportation activities. garbage transport vehicles carry garbage to a temporary dump site (tds) and end up at the �nal disposal site (fds). classic vehicle routing problem, also known as capacitated vehicle routing problem, has the characteristic that the vehicle departs from the starting point and returns to the starting point for example the route of the vehicle on the distribution of lpg gas (yuliza and puspita, 2019). the route of the waste transportation vehicle is an open vehicle routing problem (ovrp) that the garbage transporting vehicle transports waste from the tds and then takes it to the fds. the process of transporting garbage sometimes occurs with delay, such as congestion and equipment failure. robust optimization is an optimization problem approach for data that has uncertainty. de la vega et al., 2019 formulated an optimization model for the robust vehicle routing problem (rvrp) with time windows and multiple deliverymen. sungur et al., 2008 and sun and wang, 2015 discuss robust optimization of the vehicle route problem with many uncertain requests. robust optimization research has experienced developments in the problem of vehicle routes, for example in the transportation and logistics sectors the robust capacitated vehicle routing problem (rcvrp) model is a robust optimization that takes into account the uncertainty of demand to minimize the cost of shipping products to costumers (gounaris et al., 2013). robust vehicle routing problem with time windows (rvrptw) is a robust optimization that takes time windows into account. agra et al., 2013 discussed rvrptw on transportation problems where delays often occur so that the travel time is uncertain. braaten et al., 2017 investigated the limit of the maximum amount of delay in the rvrptw model and this model was solved by a heuristic method based on a large adaptive neighborhood search. hartono et al., 2018 proposed a robust counterpart vehicle routing problem (rcocvrp) model for waste transportation by request using the branch and bound algorithm. puspita et al., 2018a discussed the rcocvrp model on the problem of waste transportation in sako and sukarami districts. puspita et al., 2018b discussed the rcocvrp model with a request on the problem of waste transportation in sematang borang district. research on the problem of solid waste collection and robust https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.2.53-57&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.2.53-57 yuliza, e et. al. science and technology indonesia, 6 (2021) 53-57 optimization models has been widely studied (buhrkal et al., 2012; campos and arroyo, 2016; hannan et al., 2018; nguyen et al., 2013; perea et al., 2016 ). hartono et al., 2018; puspita et al., 2018b discuss the robust counterpart open capacitated vehicle routing problem (rc-ocvrp) model. puspita et al., 2018a discussed the robust demand counterpart open capacitated vehicle routing problem (dr-cvrp) model on the problem of waste transportation routes. this research discusses the optimization modeling of robust counterpart open capacitated vehicle routing problem (rcocvrp) with soft time windows, which means that the arrival time of the vehicle in a tds (or in fds) can be equal to or more than the �nal time. yuliza et al., 2020b has proposed the rcocvrp model with time windows on the problem of transporting garbage vehicles. this model is solved with an exact approach. the rcocvrp model with time windows is solved by the cheapest insertion heuristics algorithm then solved using the gams software (yuliza et al., 2021). rcocvrp model with time windows produces optimal results solution by considering the volume of waste in each tds carried by the vehicle does not exceed the vehicle capacity, and travel time does not exceed the time of arrival of the vehicle and solved using the nearest neighbor method (yuliza et al., 2020a). this model is formulated with the limitation of vehicle capacity (q) and time windows [a,b] with uncertainty of travel time (tij) and volume of waste (qi). in this case, the vehicle arriving at a tds or fds may exceed the time windows. the rcocvrp model with soft time windows is applied to the garbage transportation route in sako district, palembang. time windows can be viewed as the time interval from the time the vehicle departs and the time the vehicle arrives at a customer (agra et al., 2013). this model aims to optimize the route of the waste transport vehicle so as to minimize the distance. this model is solved by a heuristic approach. the heuristic approach used to solve the rcocvrp model with soft time windows uses the nearest neighbor and the cheapest insertion heuristic algorithm. the nearest neighbor algorithm and the cheapest insertion heuristics algorithm have the same working principle, namely �nding the closest point from the initial point. 2. experimental section 2.1 materials primary data in the form of the names of tds and fds, vehicle capacity, time windows and service time were obtained through direct interviews with the environmental and sanitation department. secondary data in the form of distance between each tds to tds and fds and travel time are obtained from the google maps application. each sub-district has a tds as a temporary disposal site for waste transported by the department of cleanliness and the environment waste collection vehicles with uncertain waste volume. the type of vehicle for each work area is a dump truck. the garbage collection vehicle in sako sub-district has 3 working areas. the garbage collection vehicles serve several tds in work area 1, work area 2 and work area 3, respectively, table 1. time windows and waste volume in working area 1 time windows volume of waste (kg) 07:00, 07:30 q1=800 07:30, 08:00 q2=1500 08:00, 08:30 q3=600 08:30, 09:00 q4=4000 09:00, 09:30 q5=700 09:30, 10:00 q6=2000 10:00, 11:00 q7=6000 as many as 6 tds, 4 tds and 11 tds. sako district is a densely populated residential area, so the problem of transporting waste is a concern. rcocvrp model with time windows is simulated on the route of garbage collection vehicles in the working area 1. time windows and waste volume in working area 1 is shown in table 1. the distance between tds i to tds j and the distance of each tds to fds are expressed in the distance matrix as shown in table 2. it is assumed that the waste transport vehicle has an average speed of 40 km/hour. based on the results of interviews with o�cers in the environmental and sanitation department, the average service time is around 15 minutes. 2.2 methods due to their greedy nature, sometimes the nearest neighbor algorithm can skip a shorter route. however, the nearest neighbor is easy to implement and up quickly (pop et al., 2011). the cheapest insertion heuristics algorithm is able to solve the problem of vehicle routes. in the case of waste transport routes, each tds is represented as a point and the travelling from tds i to tds j can be represented as an arc. 2.2.1 nearest neighbor algorithm following are the steps of the nearest neighbor algorithm for the problem of transporting waste: step 1: find the closest distance to each tds from the initial tds as the starting node. step 2: find the closest node from the starting node provided that the garbage volume from each tds does not exceed vehicle capacity. step 3: if the garbage volume exceeds the vehicle then start again from step 1. step 4: repeat step 2 until all tds (included fds) are visited. 2.2.2 cheapest sequential insertion algorithm the principle of the cheapest sequential insertion algorithm is to make the initial route �rst. starting from arc (i, j) from the starting vertex to the destination vertex and try to insert vertex k at a certain position gives the best criteria (alatartsev et al., 2013; scutellà, 2015). the arc (i, j) with which node k is inserted is calculated using the formula in the following formula: cik + ckj − cij (1) © 2021 the authors. page 54 of 57 yuliza, e et. al. science and technology indonesia, 6 (2021) 53-57 table 2. matrix of distance (km) tds1 tds2 tds3 tds4 tds5 tds6 fds tds1 0 0.4 0.35 0.45 1.3 4.5 2.3 tds2 0 0.55 0.85 1.3 4.8 2.3 tds3 0 1.1 1.4 5.2 2.2 tds4 0 1.7 4.1 2.3 tds5 0 5.8 1.2 tds6 0 5.6 fds 0 table 3. variables variables description xij the vehicle traveling from tds i to tds j yi vehicle load when leaving tds i. ti arrival time to tds i if none of the arcs provide the best criteria then form a new route. this process is repeated until all nodes are selected. 3. results and discussion given a directed graph g = (v, a) where v = {1, 2, 3, ..., n + 1} as the set of nodes and a={(i,j) ∣ i=1,2,...,n+1 } dan j = {1, 2, ..., n + 1, i ≠ j} as a set of arcs, where nodes 1, 2, ..., n represent each tds and node n + 1 represents fds. denoted n with n ⊂ v as a set of nodes that do not start from an origin (o) and destination (d) the set t represents the set of all time windows for each node t={ai, bi ∣ i ∈ v} . the set ext(t) represents all the extreme points on t. the variables and parameters proposed is the following: the rcocvrp with time windows in working area 1 is formulated as follows: minimize 0.4x12 + 0.35x13 + 0.45x14 + 1.3x15 + 4.5x16 + 2.3x17 + 0.4x21+ 0.55x23 + 0.85x24 + 1.3x25 + 4.8x26 + 2.3x27 + 0.35x31 + 0.55x32+ 1.1x34 + 1.4x35 + 5.2x36 + 2.2x37 + 0.45x41 + 0.85x42 + 1.1x43+ 1.7x45 + 4.1x46 + 2.3x47 + 1.3x51 + 1.3x52 + 1.4x53 + 1.7x54+ 5.8x56 + 1.2x57 + 4.5x61 + 4.8x62 + 4.1x64 + 5.8x65 + 5.6x65+ 5.6x67 + 2.3x71 + 2.3x72 + 2.2x73 + 2.3x74 + 1.2x75 + 5.6x76 (2) based on the data in table 1 and table 2, the rcocvrp model with time windows aims to minimize the distance traveled by waste transport vehicles so that the objective function is formulated as equation 2. subject to x12 + x13 + x14 + x15 + x16 + x17 = 1, x21 + x23 + x24 + x25 + x26 + x27 = 1, x31 + x32 + x34 + x35 + x36 + x37 = 1, x41 + x42 + x43 + x45 + x46 + x47 = 1, x51 + x52 + x53 + x54 + x56 + x57 = 1, x61 + x62 + x63 + x64 + x65 + x67 = 1, x71 + x72 + x73 + x74 + x75 + x76 = 1 (3) garbage transport vehicles visit each node only as constraints (3) is de�ned as at least one trip by a waste transport vehicle from node i to node j and at least one trip by a waste transport vehicle from node j to node i. x21 + x31 + x41 + x51 + x61 + x71 − x12 − x13 − x14 − x15 − x16− x17 = −1; x17 + x27 + x37 + x47 + x57 + x67 − x71 − x72 − x73 − x74− x75 − x76 = 1; x12 + x32 + x42 + x52 + x62 + x72 − x21 − x23 − x24− x25 − x25 − x27 = 0; x13 + x23 + x43 + x53 + x63 + x73 − x31 − x32− x34 − x35 − x36 − x37 = 0; x14 + x24 + x34 + x54 + x64 + x74 − x41− x42 − x43 − x45 − x46 − x47 = 0; x15 + x25 + x35 + x45 + x65 + x75− x51 − x52 − x53 − x54 − x56 − x57 = 0; x16 + x26 + x36 + x46 + x56+ x76 − x61 − x62 − x64 − x64 − x65 − x6767 = 0 (4) constraints (4) ensure that no sub-tours are cut o� for each node visited by the garbage transport vehicle and the vehicles traveling from tds i to tds j are the same as vehicles from tds j to tds i. 800 ≤ y1 ≤ 8000, 1500 ≤ y2 ≤ 8000, 600 ≤ y3 ≤ 8000, 4000 ≤ y4 ≤ 8000 700 ≤ y5 ≤ 8000, 2000 ≤ y6 ≤ 8000, 0 ≤ y7 ≤ 8000 (5) constraint (5) states that the load of waste transport vehicles is limited by the volume of waste and the capacity of the vehicle. y1 − y2 + 8000x12 ≤ 4500, y2 − y3 + 8000x23 ≤ 5400, y3 − y4+ 8000x34 ≤ 2000, y4 − y5 + 8000x45 ≤ 5300, y5 − y6 + 8000x56 ≤ 4000, y6 − y7 + 8000x37 ≤ 0 (6) © 2021 the authors. page 55 of 57 yuliza, e et. al. science and technology indonesia, 6 (2021) 53-57 table 4. parameters parameters description cij distance between tds i to tds j and the distance of each tds to fds qi load of waste transport vehicles tij travel time from tds i to tds j. ai departure time from tds i bj vehicle arrival time at tds j table 5. the solution of the rcocvrp model with time windows in working area 1 route distance (km) tds 1 – tds 3 – tds 2 – fds 3.2 nearest neighbor algorithm tds 4 – tds 5 – fds 2.9 tds 6 – fds 5.6 cheapest insertion heuristic algorithm tds 1 – tds 2 – tds 3 – fds 3.15 tds 4 – tds 5 – fds 2.9 tds 6 – fds 5.6 the volume of waste is uncertain so that the load of garbage vehicles at each node is formulated as constraints (6). 7 ≤ t1 ≤ 7.5, 7.5 ≤ t2 ≤ 8, 8 ≤ t3 ≤ 8.5, 8.5 ≤ t4 ≤ 9, 9 ≤ t5 ≤ 9.5, 9.5 ≤ t6 ≤ 10.5, 10.5 ≤ t7 ≤ 11, (7) the vehicle travel time when visiting node i is limited by the time windows formulated by constraints (7). t1 − t2 + 0.01x12 ≤ 0, t2 − t3 + 0.01375x23 ≤ 0, t3 − t4 + 0.0275x34 ≤ 0, t4 − t5 + 0.0425x45 ≤ 0, t5 − t6 + 0.145x56 ≤ 0, t6 − t7 + 0.14 x67 ≤ 0 (8) vehicle arrival time at node i is in�uenced by departure time, travel time and vehicle arrival time at node j formulated by constraints (8). the calculation of the rcocvrp model with time windows is solved by the nearest neighbor algorithm simulated in the working area 1. furthermore, the calculation of the rcocvrp model with time windows is solved by the cheapest insertion heuristic algorithm. the route of waste transport vehicles in working area 1 uses the nearest neighbor algorithm and the cheapest insertion heuristics algorithm is shown in table 5. the total distance of waste transport vehicles in working area 1, respectively, using the nearest neighbor method and the cheapest insertion heuristic algorithm are 11.65 km and 11.7 km. the results of calculations using these two heuristic approaches are almost the same. this is in�uenced by the working principle of these two heuristic approaches is to �nd the closest point. the results for working area 2 and working area 3 use the nearest neighbor algorithm and the cheapest insertion heuristics algorithm as shown in table 6. based on table 5 and table 6, it is obtained that the total distance of waste transport vehicles in sako sub-district using the nearest neighbor algorithm is 54.29 km and the total distance traveled using the cheapest insert heuristic algorithm is 54.24 km. the rcocvrp model with time windows to optimize the route problems of waste transport vehicles that is solved using the cheapest insertion heuristics algorithm is more e�ective than the nearest neighbor method. the basic principle of the nearest neighbor method is to �nd the minimum distance from each arc (i, j). the cheapest insertion heuristic algorithm inserts each node k on arc (i, j). then �nd the minimum distance between the two insertion arcs so that the node not visited can be avoided. 4. conclusions rcocvrp with time windows can be used to solve waste transportation route problems. the results of the calculation of this model using the nearest neighbor method and the cheapest insertion heuristics algorithm produce almost the same solution because the principle of these two heuristic approaches is to �nd the closest distance. the cheapest insertion heuristics algorithm is more e�cient than the nearest neighbor algorithm for determining the route of the waste transport vehicle. from the calculation results, it is found that the cheapest insertion heuristic algorithm is more e�cient than the nearest neighbor 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for the robust vehicle routing problem with time windows. expert systems with applications, 77; 136–147 buhrkal, k., a. larsen, and s. ropke (2012). the waste collection vehicle routing problem with time windows in a city logistics context. procedia-social and behavioral sciences, 39; 241–254 campos, a. a. and j. e. c. arroyo (2016). an ils heuristic for the waste collection vehicle routing problem with time windows. advances in intelligent systems and computing, 557; 889–899 de la vega, j., p. munari, and r. morabito (2019). robust optimization for the vehicle routing problem with multiple deliverymen. central european journal of operations research, 27(4); 905–936 gounaris, c. e., w. wiesemann, and c. a. floudas (2013). the robust capacitated vehicle routing problem under demand uncertainty. operations research, 61(3); 677–693 hannan, m., m. akhtar, r. begum, h. basri, a. hussain, and e. scavino (2018). capacitated vehicle-routing problem model for scheduled solid waste collection 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(2015). logistics. in lecture note; 91–103 sun, l. and b. wang (2015). robust optimisation approach for vehicle routing problems with uncertainty. mathematical problems in engineering, 2015; 1–8 sungur, i., f. ordónez, and m. dessouky (2008). a robust optimization approach for the capacitated vehicle routing problem with demand uncertainty. iie transactions, 40(5); 509–523 yuliza, e. and f. puspita (2019). the branch and cut method for solving capacitated vehicle routing problem (cvrp) model of lpg gas distribution routes. science and technology indonesia, 4(4); 105–108 yuliza, e., f. puspita, s. supadi, and s. octarina (2020a). the robust counterpart open capacitated vehicle routing problem with time windows. journal of physics: conference series, 1663(1); 1–7 yuliza, e., f. m. puspita, and s. s. supadi (2020b). the robust counterpart open capacitated vehicle routing problem with time windows on waste transport problems. bulletin of electrical engineering and informatics, 9(5); 2074–2081 yuliza, e., f. m. puspita, and s. s. supadi (2021). robust optimization for the counterpart open capacitated vehicle routing problem with time windows. advances in social science, education and humanities research, 513; 556–560 © 2021 the authors. page 57 of 57 introduction experimental section materials methods nearest neighbor algorithm cheapest sequential insertion algorithm results and discussion conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 1, january 2021 research paper preparation and characterization of ethosomes loading petai pods extract (parkia speciosa hassk.) fitrya1, najma annuria fithri1, annisa amriani1, annisa haryati1, dina permata wijaya1* 1department of pharmacy faculty of mathematics and natural science, sriwijaya university *corresponding author: dinapermatawijaya@unsri.ac.id abstract preparation of petai pods extract (parkia speciosa) into ethosome aim to increased penetration through the skin. the method of cold is used in preparing petai pods extract encapsulation by ethosome with variation in concentration of soya lecithin, propylene glycol, and ethanol. the proportion of optimum formula ethosome consisted were 0.2 g soya lecithin, 1 ml propylene glycol, and 4 ml ethanol that response values obtained ph of 4.74, viscosity of 0,950 cp, %ee of 74.326%, and stability of 7.288%. the resulted of optimum formula obtained were pdi of 0.23, zeta potential of -7.5 mv, and particle size of 818.7 nm. ethosome showed spheric particle using transmissin electron microscopy. the di�usion analysis showed highest on ethosome of petai pods extract (9.525%) than petai pods extract (5.466%). the interaction study used ftir show no chemical interaction extract pods and ethosome components. keywords ethosome, petai pods, extract, soya lechitin, propylene glycol, ethanol received: 9 november 2020, accepted: 15 december 2020 https://doi.org/10.26554/sti.2021.6.1.19-24 1. introduction petai (parkia speciosa hassk.) has been long used by public especially in indonesia as food ingredients but petai pods not used and only being waste. petai pods have phytochemical compounds such as phenolics and �avonoids compound (fithri et al., 2019). phenolics and �avonoids compound have high antioxidants activity that needed by human body (ko et al., 2014). flavonoids can protect cell from free radicals and increase cell integrity. besides having high antioxidants activity, �avonoids also have activity as anti-in�ammatory, wound healing, and skin aging. flavonoids have poor oral bioavailability and absorption due to its poor aqueous solubility.the stability of �avonoids in gastrointestinal tract is poor because its can go through enzymatic hydrolysis (ramadon et al., 2018). the penetration mechanism of �avonoids into cell also can be limited due to its poor aqueous solubility and lipophilicity partition coe�cient (logp= 1.82) as the cause of nonpolar group in its structure (vickers, 2017). the limitation of penetration in the delivery �avonoids compund into the skin requires a novel delivery system. transdermal delivery system have high potentially for resolve this limitation. one of transdermal delivery system known as nanovesicles, its a method that used increase the penetration of active substances into the skin. ethosomes are a nanovesicles system that have high potential as penetration enhancer of �avonoids into skin (ramadon et al., 2018). ethosomes are phospholipid-based elastic nanovesicles containing a high content of ethanol (20–45%) and water. ethanol can be used as penetration enhancer in vesicles system and make the ethosomes more elastic, its can disturb the lipid bilayer on skin (verma and pathak, 2010). propylene glycol used as penetration enhancer. the concentration of propylene glycol mainly used for ethosomes is 5-20% and it in�uenced the size, stability, encapsulation e�ciency, and penetration of etosomes into the skin (abdulbaqi et al., 2016). in this study, petai pods extract (parkia speciosa) loaded ethosomes were formulated, then it performed in vitro penetration test using franz di�usion cells. chemical interaction between material for making ethosomes and petai pods extract also analyzed. 2. experimental section 2.1 materials the materials used in this research were petai pods extract (parkia speciosa hassk.) obtained from the unsri pharmacy department, soya lecithin (pt. lansida), ethanol (pt. dira sonita), propylene glycol (pt. bratachem), cellophane membrane (merck), quercetine (sigma-aldrich®), alcl3 (pt. bratachem) and solvents with technical quality and p.a obtained from pt. bratachem and merck. https://doi.org/10.26554/sti.2021.6.1.19-24 fitrya et. al. science and technology indonesia, 6 (2021) 19-24 2.2 extraction petai pods (parkia speciossa hassk.) extract preparation was carried out based on previous research. the 4 kg of dry simplisia petai pods (parkia speciosa), crushed using a blender. petai pods powder is macerated with 6 l of 70% ethanol, stirred, and let stand for 48 hours. the resulting maserate is �ltered with �lter paper to obtain the �ltrate. the resulting �ltrate is remacerated to obtain a clear �ltrate. the resulting �ltrate was concentrated using a rotary evaporator at a temperature of 60oc and a speed of 35 rpm to remove the solvent and a thick extract was obtained then the percent yield was calculated. the thick extract was identi�ed and the levels of �avonoids were calculated using quercetin as a marker compound. 2.3 formulation of petai pods extract (parkia speciossa hassk.) loaded ethosomes formulation of petai pods extract (parkia speciosa) loaded ethosomes in this research varied the amount of lecithin soybean (0.2 g; 0.6g), propylene glycol (1 ml; 2 ml), and 96% ethanol (4 ml; 8 ml). the formula used can be seen in table 1. petai pods extract (parkia speciosa) loaded ethosomes was prepared using the cold method. the petai pods extract was dissolved in 96% ethanol, stirred using a magnetic stirrer at a speed of 700 rpm for 10 minutes. the homogeneous extract was added with soy lecithin and then homogenized using a magnetic stirrer with a speed of 700 rpm for 5 minutes. propylene glycol is added to the mixture and homogenized using a magnetic stirrer for 20 minutes at room temperature. distilled water was added to the mixture while stirring with a magnetic stirrer at 30oc. the ethosome was homogenized with an ultrasonic bath (gt sonic® vgt-1620qtd 50 khz) with frequency of 50 khz for 30 minutes. petai pods extract (parkia speciosa) loaded ethosomes was stored at 4oc. 2.4 analysis of response petai pods extract (parkia speciossa hassk.) loaded ethosomes 2.4.1 determination of ph ph test for each formula was carried out using a ph meter (lutron® ph electrode pe-03) dipped into the petai pods extract (parkia speciosa) loaded ethosomes. the ph result of each formula is displayed on the ph meter screen. 2.4.2 determination of viscosity the viscosity test was carried out using an ostwald viscometer (ptc chemical equipment). the viscosity test is carried out by measuring the time of �ow velocity in the ostwald viscometer tube. 2.4.3 determination of percent of encapsulation e�ciency (%ee) the %ee test was started with petai pods extract loaded ethosomes centrifuged (dlab ©: d2012 plus) at a speed of 10,000 rpm for 90 minutes. the supernatant was taken and measured the levels of �avonoids that were not absorbed in the ethosomes vesicles using a uv-vis spectrophotometer with a length of 436 nm where quercetin was used as a marker compound. 2.4.4 stability testing of petai pods extract loaded ethosomes the stability test of the petai pods extract loaded ethosomes was determined using the cycling test method for 6 cycles. stability testing was carried out by placing each ethosome formula at 4oc for 24 hours then transferred at 40oc for 24 hours. measurement of petai pods extract levels was carried out in the last cycle (6th cycle) using a uv-vis spectrophotometer with a wavelength of 436 nm (quercetin). 2.5 fomula optimization determination of the optimum formula of petai pods extract loaded ethosomes is determined from the relationship between the components of soy lecithin, propylene glycol, and ethanol with the interaction of each response, namely ph, viscosity,% ee, and stability. the optimum formula analysis uses the dx® 10 program. 2.6 optimal formula characterization measurement of particle diameter, polydispersion index, and zeta potential was carried out using the particle size analyzer (psa) (horiba scienti�c® sz-100) with the dynamic light scattering (dls) method. a total of 50 µl of the petai pods extract loaded ethosomes was added to the psa cuvette. 2.7 determination of surface morphology the surface morphology particles of petai pods extract loaded ethosomes was determined using a transmission electron microscopy (tem) (jeol® jem 1400) device. the ethosomes optimum formula of petai pods extract as much as 50 µl was diluted 100 times with distilled water. the ethosomes formula sample was observed under a digital focusing microscope using a voltage of 10 kv and 30 kv. 2.8 in vitro di�usion of ethosomes testing in-vitro di�usion testing was carried out using franz di�usion cells (fdc) and pbs solution ph 7.4. a total of 2 ml of petai pods extract loaded ethosomes was evenly placed on the cellophane membrane and stirred with a magnetic stirrer at a speed of 400 rpm at 35oc. sampling was done at minute: 0; 5; 10; 15; 30; 45; 60; 120; 180; 240; 300; 360; 420; 480; 540; 600; 660; 720. the absorbance is measured at a maximum wavelength of 436 nm. in-vitro di�usion was carried out on the petai pods extract and petai pods extract loaded ethosomes. 2.9 chemical interaction with ftir the determination of the chemical interactions of petai pods extract loaded ethosomes, placebo ethosomes, and petai pods extracts was carried out using ftir. the ftir spectrum will produce an interpretation of chemical interactions and functional groups. 3. results and discussion the petai peel extraction process produced a thick extract of 1.029 kg with 25.72% yield. the yield percentage indicated the © 2021 the authors. page 20 of 24 fitrya et. al. science and technology indonesia, 6 (2021) 19-24 table 1. formulation of petai pods extract (parkia speciosa) loaded ethosomes formulation extract of petai soya propylene ethanol aquadestpods (mg) lecithin (g) glycol (ml) (ml) (ml) f1 440 0.2 1 4 ad 20 f2 440 0.6 1 4 ad 20 f3 440 0.2 2 4 ad 20 f4 440 0.6 2 4 ad 20 f5 440 0.2 1 8 ad 20 f6 440 0.6 1 8 ad 20 f7 440 0.2 2 8 ad 20 f8 440 0.6 2 8 ad 20 number of components or secondary metabolites extracted during the maceration process and the e�ectiveness of the extraction process. 3.1 determination of total flavonoid determination of total �avonoid in petai pods extract using quercetin compound as a marker. the maximum wavelength is determined by the addition of alcl3 which will react with quercetin. the maximum wavelength resulting from the scanning process is 436 nm. the maximum wavelength obtained was used to test the percent e�ciency of encapsulation and to test the stability of the petai pods extract content in the ethosomes. the total of �avonoids contained in the extract was 35.706 mg/g. 3.2 formulation of petai pods extract loaded ethosomes the petai pods extract loaded ethosomes is formulated using components consisting of soya lecithin, propylene glycol, and 96% ethanol. soya lecithin is used in ethosomes formulas because it contains unsaturated fatty acids that have compatibility in the body, good penetration into the skin, and a relatively cheap price. propylene glycol can increase the �exibility of the ethosomes vesicles, thereby increasing di�usion into the skin. meanwhile, the addition of ethanol can increase the penetration of ethosomes vesicles through the stratum corneum. the mechanism of penetration of the ethosomes in the skin is by disrupting the lipid structure of the stratum corneum and having good �exibility so it can deform when it passes through the stratum corneum to penetrate the stratum cornea. this can occur because of the high concentration of ethanol in the ethosomes formulation (korade et al., 2016). the selection of methods making ethosomes used the cold method because �avonoids are compounds that are unstable to heat. the results of the preparation of the ethosomes formula can be seen in figure 1. ethosome preparations with a low concentration of soya lecithin have a lighter color than those with a high concentration of soy lecithin. the high concentration of soy lecithin can cause the size of the ethosomes vesicles to get bigger. table 2. ph determination of petai pods extract (parkia speciosa) loaded ethosomes formulation mean ± sd cv (%) f1 4.74 ± 0.008 0.211 f2 4.84 ± 0.005 0.119 f3 4.70 ± 0.012 0.324 f4 4.82 ± 0.015 0.315 f5 4.83 ± 0.012 0.317 f6 5.13 ± 0.011 0.225 f7 4.86 ± 0.014 0.355 f8 4.92 ± 0.010 0.204 3.3 determination of ph analysis the results of ph test petai pods extract loaded ethosomes were obtained in the range 4.71-5.14 into the desired criteria, namely 4.5-7.0. data from ph testing results can be seen in table 2. ph preparations that are too acidic or alkaline can irritate because the skin becomes dry. observation of the ph response on each factor has a signi�cant e�ect with a p-value <0.0001. based on the ph response equation, soy lecithin and ethanol can increase the response value while propylene glycol decreases the response value because it has a ph that tends to be acidic. based on the ph response equation, the interaction between soy lecithin, propylene glycol, and ethanol can reduce ph. this is in�uenced by the propylene glycol and petai pods extract components, which have a ph that tends to be acidic. the following is the equation of the factorial design of the combination of ethosomesforming components to ph: ph = 4, 86+0, 073a−0, 073b+0, 078c −0, 036ab+0, 017ac −0, 019bc − 0, 039ab (1) description: a: soya lecithin concentration b: propylene glycol concentration © 2021 the authors. page 21 of 24 fitrya et. al. science and technology indonesia, 6 (2021) 19-24 c: ethanol concentration ab: interaction of soy lecithin with propylene glycol ac: interaction of soy lecithin with ethanol bc: interaction of propylene glycol with ethanol 3.4 viscosity analysis table 3. viscosity determination of petai pods extract (parkia speciosa) loaded ethosomes formulation mean ± sd(cp) cv (%) f1 0.950 ± 0,009 0.969 f2 1.287 ± 0,020 1.593 f3 1.427 ± 0,016 1.152 f4 1.817 ± 0,036 2.042 f5 1.255 ± 0,026 2.135 f6 1.564 ± 0,017 1.13 f7 1.088 ± 0,013 1.268 f8 1.145 ± 0,026 2.281 viscosity analyze was carried out to determine the viscosity properties of the prepared ethosome. observation of the viscosity response on each factor has a signi�cant e�ect with a p-value <0.0001. based on table 3, ethosomes with high soy lecithin concentrations produce an increased viscosity compared to low soy lecithin concentrations. this is because the viscosity of soy lecithin is high so that it can signi�cantly a�ect the viscosity of the ethosome. based on the viscosity response equation, the concentration of soy lecithin can increase the viscosity response. the interaction of soy lecithin, propylene glycol, and ethanol can reduce the viscosity response. y = 1, 31+0, 14a+0, 05b−0, 059c−0, 029ab−0, 045ac−0, 019bc −0, 032abc (2) description: y: viscosity response a: soya lecithin concentration b: propylene glycol concentration c: ethanol concentration ab: interaction of soy lecithin with propylene glycol ac: interaction of soy lecithin with ethanol bc: interaction of propylene glycol with ethanol 3.5 encapsulation e�ciency analysis the percentage of encapsulation e�ciency aims to determine the amount of extract absorbed in the ethosomes vesicles. the determination of% ee was carried out by puri�cation of the ethosomes through centrifugation at a speed of 10,000 rpm for 90 minutes. the supernatant obtained was measured using a uv-vis spectrophotometer with a wavelength of 436 nm using the quercetin standard. the results of the %ee test show that formula 1 has the highest %ee while formula 7 has the lowest %ee. based on the %ee response, the concentration of soy lecithin, propylene glycol and ethanol can signi�cantly reduce %ee with a p-value <0.0001. soya lecithin is a former of ethosome vesicles so that the addition of high concentrations can cause the vesicles to be more �exible and cause leaks so that the %ee of active substances decreases (estanqueiro et al., 2014). the interaction of propylene glycol and ethanol can signi�cantly reduce the %ee of the active substance which can show a synergy e�ect to increase the permeability of ethosome vesicles (barupal et al., 2010). %ee = 63, 43−0, 21a−5, 6b−4, 29c−0, 96ab+4, 11ac−0, 75bc +1, 66abc (3) description: a: soya lecithin concentration b: propylene glycol concentration c: ethanol concentration ab: interaction of soy lecithin with propylene glycol ac: interaction of soy lecithin with ethanol bc: interaction of propylene glycol with ethanol 3.6 stability of ethosomes analysis ethosomes stability was performed to determine the resistance of ethosomes preparations to temperature changes. ethosomes have vesicles that are tight, compact, and do not leak before testing. giving heat treatment causes the vesicles to stretch because of the breaking of the bonds between the lipid constituents so that heat exposure can cause the vesicles to leak. treatment at cold temperatures will cause the components that form the ethosome to form tightly back into aggregates, but the vesicles that have leaked and separated cannot return to the form of a complete ethosome. the extracts that had come out of these ethosome vesicles were measured for the ethosome stability of the petai pods. the results of decreasing levels of petai pods extract can be seen in table 4. table 4. %ee determination of petai pods extract (parkia speciosa) loaded ethosomes formulation mean ± sd(%) cv (%) f1 74.326 ± 0,079 0.107 f2 70.940 ± 0,079 0.112 f3 69.755 ± 0,079 0.114 f4 55.874 ± 0,079 0.142 f5 62.363 ± 0,079 0.127 f6 68.739 ± 0,079 0.116 f7 48.144 ± 0,079 0.165 f8 57.341 ± 0,079 0.241 © 2021 the authors. page 22 of 24 fitrya et. al. science and technology indonesia, 6 (2021) 19-24 table 5. determination of percent reduction in �avonoid levels in stability test formula mean (%) ± sd cv (%) f1 7.288 ± 0.079 0.107 f2 4.295 ± 0.079 0.112 f3 11.891 ± 0.079 1.765 f4 11.412 ± 0.079 1.187 f5 19.634 ± 0.079 0.598 f6 10.918 ± 0.079 1.126 f7 15.237 ± 0.079 2.262 f8 7.970 ± 0.079 0.241 based on the results of the response of all factors to the stability of the petai pods extract levels, it shows that soy lecithin can signi�cantly increase ethosome stability. this is because soy lecithin is a component of ethosomes vesicles and does not leak easily. propylene glycol and ethanol can increase the percentage reduction in the content of petai bark extract in the etosome vesicles. this is because ethanol can increase permeability so that the petai pods extract can come out of the etosome vesicles. y = 11, 08−2, 43a+0, 55b+2, 36c+0, 5ab−1, 56ac−2, 38bc −0, 13abc (4) description: y: decreased level response a: soya lecithin concentration b: propylene glycol concentration c: ethanol concentration ab: interaction of soy lecithin with propylene glycol ac: interaction of soy lecithin with ethanol bc: interaction of propylene glycol with ethanol table 6. the results of statistical analysis of predictive value of dx® 10 of formula ethosome evaluation dx® 10 prediction experiment ± sd p-value ph 4.729 5.023±0.016 0.001 viscosity 1 0.959±0.0015 0.008 %ee 73.816 73.761±0.138 0 stability 7.801 7.200±0.104 0.389 optimization of the optimum formula for petai pods extract loaded ethosomes was carried out using the dx® 10 program showed table 6. the optimum formula for ethosomes ware determined based on the analysis of the results of the response to ph, viscosity, %ee, and the stability of levels of petai pods extract in the ethosomes. there are 4 responses to determine the optimum formula, namely ph, viscosity, %ee, and the stability figure 1. morfology particles of petai pods extract (parkia speciosa) loaded ethosomes using tem of extract content. %ee has the criteria for determining the maximum optimum formula because of the amount of extract that can be absorbed into the vesicles. the higher the %ee, the more active substances are absorbed so that it can provide maximum activity. the highest %ee value is shown in formula 1, namely 74.326%. this is the use of soy lecithin with a concentration of 1% can form vesicles that are more stable in absorbing the extract. the stability of the decrease in extract content has a criterion of 5, the lower %value of decreased stability then more stable the preparation is. formula 1 has a decreased percentage of extract content of 7,288%. the desired stability value is in a low range. particles diameter and distribution are important parameters of the ethosome vesicles. this parameter will a�ect the ability of the ethosomes to enter or penetrate into the skin (limsuwan et al., 2017). the particles diameter resulted from the ethosome of the petai skin extract was 818.7 nm. vesicles with a diameter of 810 can pass through the stratum corneum and deposit as much as 39.952% (verma and pathak, 2010). this indicates that ethosomal vesicles can accumulate in the skin. the particle size distribution is determined by the polydispersity index value which indicates the uniformity of particle size. the polydipersity index value of petai pods extract loaded ethosomes was 0.231 indicating that there were 76.9% of the total number of particles in the ethosome formula of petai pods extract loaded ethosomes which had a homogeneous size. this ethosomes have a pdi value <0.5 which indicates that the diameter distribution of the ethosome particles tends to be homogeneous. zeta potential will show the charge size of a particle which that show an e�ect on the stability of the particles during storage. stable zeta potential is represented by values greater than +25 mv or more than -25 mv. the zeta potential value of the petai pods extract loaded ethosomes is -7.5mv, the negative value obtained is in�uenced by the ethosome-forming components, which is contributed by the phosphate group of lecithin and oxygen atoms which are electronegative from the hydroxy group in the propylene glycol and ethanol components. the zeta potential value obtained indicates that ethosome particles have a tendency to form aggregates because of the low repulsion between particles. the particle morphology produced by the petai pods extract loaded ethosomes shows a spheric (round) shape (figure 1). the spheric particle form has the ability to enter the body’s cells better than the rod shape (chithrani and chan, 2007). the spheric © 2021 the authors. page 23 of 24 fitrya et. al. science and technology indonesia, 6 (2021) 19-24 figure 2. expectation was physical interaction between extract and ethosomes using ftir figure 3. graph mean percentage of di�usion extract petai pods dan petai pods extract (parkia speciosa) loaded ethosomes shape is easier to penetrate into the body because the surface area of the particles in contact is wider than that of the rod. the di�usion test was carried out to determine the amount of petai pods extract in ethsomes that could penetrate into the skin compared to the petai pods extract. the parameter used to determine the di�usion test is the percent di�usion. a high percent di�use value may indicate that the extract can penetrate more deeply into the skin. the average result percent di�usion of petai pods extract loaded ethosomes was more than the petai pods extract result. this is due to the presence of ethosome vesicles which have deformability properties that can help the extract penetrate into the skin. percent di�usion was analyzed using one way anova with p-value <0.05, which indicates that there is a signi�cant di�erence between the di�used percent of the extract and the petai pods extract loaded ethosomes (figure 2). the chemical interactions that occur between the ethosome formers and the petai skin extract were analyzed using ftir. the intensity that appears in the spectra is in�uenced by the concentration of the sample. based on the ftir results, there was no interaction between palsebo and extract, it can be seen that no new peaks were formed on the spectrum (figure 3). 4. conclusions the vesicle-forming components of the ethosomes a�ect the response of the percent encapsulation and the stability of the extract which is seen with the percent decrease in levels. ethosomesforming compositions that can produce an optimal formula are 0.2 g of soy lecithin, 1 ml of propylene glycol, and 4 ml of ethanol. the ethosomes optimum formula produces a higher di�use percent compared to petai pods extract. 5. acknowledgement the author thanks to grand research mathematical science faculty of sriwijaya university 2019 and to laboratory terpadu fmipa sriwijaya university, laboratory medical test, food, and cosmetic university of islam indonesia, laboratory nanotecnology pharmacy university of islam indonesia. references abdulbaqi, i. m., y. darwis, n. a. k. khan, r. abou assi, and a. a. khan (2016). ethosomal nanocarriers: the impact of constituents and formulation techniques on ethosomal properties, in vivo studies, and clinical trials. international journal of nanomedicine, 11; 2279 barupal, a., v. gupta, and s. ramteke (2010). preparation and characterization of ethosomes for topical delivery of aceclofenac. indian journal of pharmaceutical sciences, 72(5); 582 chithrani, b. d. and w. c. chan (2007). elucidating the mechanism of cellular uptake and removal of protein-coated gold nanoparticles of di�erent sizes and shapes. nano letters, 7(6); 1542–1550 estanqueiro, m., j. conceição, m. h. amaral, d. santos, j. b. silva, and j. m. s. lobo (2014). characterization and stability studies of emulsion systems containing pumice. brazilian journal of pharmaceutical sciences, 50(2); 361–369 fithri, n. a., f. fitrya, t. shabrina, and d. yulanri (2019). antioxidant activity analysis and standardization of parkia speciosa (petai) pods ethanol extract. science and technology indonesia, 4(1); 5–10 ko, h.-j., l.-h. ang, and l.-t. ng (2014). antioxidant activities and polyphenolic constituents of bitter bean parkia speciosa. international journal of food properties, 17(9); 1977–1986 korade, s., m. deshmukh, and r. shete (2016). formulation and evaluation of ethosomal gel containing clobetasol. j. eur. pharm. med. res, 3; 664–672 limsuwan, t., p. boonme, p. khongkow, and t. amnuaikit (2017). ethosomes of phenylethyl resorcinol as vesicular delivery system for skin lightening applications. biomed research international, 2017 ramadon, d., e. anwar, and y. harahap (2018). in vitro penetration and bioavailability of novel transdermal quercetin-loaded ethosomal gel. indian journal of pharmaceutical sciences, 79(6); 948–956 verma, p. and k. pathak (2010). therapeutic and cosmeceutical potential of ethosomes: an overview. journal of advanced pharmaceutical technology & research, 1(3); 274 vickers, n. j. (2017). animal communication: when i’m calling you, will you answer too? current biology, 27(14); r713–r715 © 2021 the authors. page 24 of 24 introduction experimental section materials extraction petai pods (parkia speciossa hassk.) formulation of petai pods extract (parkia speciossa hassk.) loaded ethosomes analysis of response petai pods extract (parkia speciossa hassk.) loaded ethosomes determination of ph determination of viscosity determination of percent of encapsulation efficiency (%ee) stability testing of petai pods extract loaded ethosomes fomula optimization optimal formula characterization determination of surface morphology in vitro diffusion of ethosomes chemical interaction with ftir results and discussion determination of total flavonoid formulation of petai pods extract loaded ethosomes determination of ph analysis viscosity analysis encapsulation efficiency analysis stability of ethosomes analysis conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 4, october 2019 research paper kinetic adsorption of direct yellow onto zn/al and zn/fe layered double hydroxides neza rahayu palapa1, bakri rio rahayu1, tarmizi taher2, risfidian mohadi1, aldes lesbani1 1department of chemistry, faculty of mathematics and natural sciences, sriwijaya university, jl. palembang-prabumulih, km. 32, ogan ilir, south sumatra, indonesia 2department of enviromental science, graduate school, sriwijaya university, jl. padang selasa no. 524 ilir barat 1, palembang-south sumatra, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstract zn/al and zn/fe layered double hydroxides has successfully synthesized by co-precipitation methods with molar ration 3:1. the samples were characterized using x-ray di�raction, fourier transform infrared spectroscopy and surface area using bet method. in this study, zn/al and zn/fe layered double hydroxides were used to remove direct yellow dye in aqueous solution. the experiments were carried out time variations with the aim of observing the kinetic studies. the results showed that the adsorption of direct yellow onto zn/al and zn/fe layered double hydroxides based on co-e�icient correlation kinetic models more fit using pseudo-second-order than pseudo-first-order. keywords adsorption, dye, layered double hydroxides, kinetic study, co-precipitation received: 21 september 2019, accepted: 19 october 2019 https://doi.org/10.26554/sti.2019.4.4.101-104 1. introduction layered double hydroxides as known as anionic clays with a positive charge excess in their brucite like layers and anion species in interlayer as counter balancing (gong et al., 2013). in general, layered double hydroxides has formula [m2+(1−x)m 3+x(oh)2](an − )x/nh2o where, m 2+ is divalent metal cation and m3+ is trivalent metal cation (ke�f et al., 2019; palapa et al., 2019). layered double hydroxides is one of most considered attention in recent years with their ability to remediation wastewater were contains dye, toxic metals and organic pollutant in aqueous solution (meng et al., 2019). layered double hydroxides were widely used to adsorbent caused their ability. the bene�ts of layered double hydroxides are easy to synthesized, high �exibility structure and easy to modi�ed (gonçalves et al., 2019). dyes e�uent contained with wastewater can be bad impact to environment. the remediation technique of wastewater has been studied. the di�erent physical or chemical methods has advantages and disadvantages. the examples of chemical technique such as photocatalysis (hidayati et al., 2019), and physicochemical methods such as ion exchange, coagulation, adsorption and membrane �ltration (kazeem et al., 2019). many of them are expensive, hard to use and has limitation of dye separation e�ciency (daud et al., 2019; hidayati et al., 2019). however, the adsorption method has more advantages which is this method are more useful, low cost, easy to used and have no pollutant (dos santos et al., 2017; milagres et al., 2017). in this study, zn/al-ldh and zn/fe-ldh was applied to removal direct yellow dye in wastewater. as known, synthetics dye has bad impact to bodies and environment. according to kausar et al. (2018) direct dyes are usually used for leather industries, cotton and rayon dyeing and paper industries. the main classes of direct dyes include poly azo and oxazine compounds palapa et al. (2018a). these dyes have a high a�nity of dyeing process on cellulosic �ber in aqueous solution. in palembang, these dyes are most popular used for jumputan home industries. many of craftsmen assumed that direct dyes have e�ect brighter than other synthetic dyes. in other hand, direct dye was reported that the e�ect health to body is bladder cancer carcinogen sun et al. (2010); zhang et al. (2018); palapa et al. (2018b). this research was removal direct yellow using layered double hydroxides (ldh) by adsorption method. the amount of absorbed were calculated and studied by kinetic models. kinetic models were �tted are pseudo-�rst-order and pseudo-second-order. 2. experimental section 2.1 materials the chemicals all purchased by merck such as aluminum nitrate nonahydrate, iron nitrate nonahydrate, zinc nitrate hexahydrate, and sodium hydroxide. nitrogen gas were pro-analytic and the solution was prepared by deionized purity water. then characterized by xrd di�ractometer rigaku mini�ex-600 and https://doi.org/10.26554/sti.2019.4.4.101-104 palapa et. al. science and technology indonesia, 4 (2019) 101-104 spectrophotometer ft-ir shimadzu ft-ir prestige-21. 2.2 synthesis of layered double hydroxides zn/al-ldh was synthesized using a co-precipitation method. a mixed-metal nitrate solution (0.25 m zn2+ and 0.08 m al3+) was adjusted to the solution ph of 9–10 by adding the required amount of 2 m naoh. the mixture was �owed nitrogen system and heated to 80 °c for 18 h. the white precipitate was formed. subsequently, it was �ltered and rinsed with deionized water. after drying at 85 °c, the obtained material was ground gently into a �ne powder. zn/fe-ldh was synthesis by zn(no3)2 ·6h2o and fe(no3)3 ·9h2o salt solution were mixed in a desired zn (ii)/fe (iii) 3:1 molar ratio and titrated slowly with the basic solution of 2m naoh until the ph reached 10.0 at room temperature maintaining a nitrogen atmosphere. the brown precipitate was formed then the mixed solution was �ltered and rinse with deionized water, drying at 80 °c to obtain powdery ldh. 2.3 e�ect of contact time adsorption direct yellow by zn/al-ldh and zn/fe-ldh the adsorption of direct yellow onto zn/al-ldh and zn/feldh was performed taking 50 ml from sample solution 100 mg/l. 0.05 g of zn/al-ldh and zn/fe-ldh were contact to 50 ml direct yellow 100 mg/l. the mixing solution were shake in horizontal shaker 250 rpm by varying times (between 5-180 min). the solution was centrifuged and the �ltrate was analyses using uv-vis spectrophotometer at 403 nm. before analyses, �ve point of standard curve has been examined and coe�cient correlation was linear amount 0.99. the amount of adsorbed were calculated from initial concentration and equilibrium concentration in supernatant after centrifugation. after that, the data were tested using kinetic models. the kinetic model was used pseudo-�rst-order and pseudo-second-order. the kinetic parameters are calculated using the pseudo-�rst-order: log(qe − qt) = logqe − k1/(2.303)t (1) and pseudo-second-order equations as follows: t/qt = (1/k2qe2) + (1/qe)t (2) where qt is the amount of adsorbate adsorbed at time t (mg.g−1), qe is the adsorption capacity in the equilibrium (mg g−1), k1 is the pseudo-�rst-order rate constant (min−1), k2 is the pseudo-second-order rate (g mg−1min−1) and t is the contact time (min) [6,13]. 3. results and discussion 3.1 characterization of layered double hydroxides zn/al-ldh and zn/fe ldh has been successfully prepared and characterized using xrd and ftir. in fig. 1. shows the xrd pattern of zn/al-ldh and zn/fe-ldh. the booth of di�ractograms were shows high crystallinity and speci�c di�raction of ldh was shows at amount 11° about interlayer distance (taher et al., figure 1. xrd pattern of zn/al-ldh and zn/fe-ldh figure 2. ftir spectra of zn/al-ldh and zn/fe-ldh 2019). the distance of interlayer zn/al-ldh and zn/fe-ldh is 7.57 å and 5.80 å, respectively. fig. 2. shows the spectra of both layered double hydroxides. both spectra have similar spectra. the presence of vibrations at wavenumber about 3400 cm−1 which is oh vibration from hydroxyl group and about 1635 cm−1 a identi�ed the presence of water molecules in interlayer. the sharp peaks at 1381 cm−1 were indicated the vibration of nitrate. the vibration of metal-oxide are shows at 700-900 cm−1. 3.2 e�ect of adsorption time direct yellow by zn/al ldh and zn/fe-ldh the comparison of zn/al-ldh and zn/fe-ldh was showed in fig. 3. the adsorption e�ciency was increased rapidly at 100 min for zn/al-ldh with amount of dye adsorbed is reach 71.93% from 100 mg/l and zn/fe-ldh about 51.24% for adsorb direct yellow from 100 mg/l. layered double hydroxides both are increasing rapidly thereafter becomes slow until reach equilibrium. is caused layered double hydroxides has available active site before equilibrium, so that layered double hydroxides can adsorb rapidly. dyes sorption of zn/al-ldh higher than zn/fe-ldh. the di�erence of equilibrium times and e�ciency adsorbed may cause the zn/fe-ldh has smaller interlayer than zn/al-ldh. © 2019 the authors. page 102 of 104 palapa et. al. science and technology indonesia, 4 (2019) 101-104 according to ulibarri and hermosin (2006) that the adsorption of anionic contaminant can be adsorb into surface active site and sometimes exchanges mechanism can be happen in interlayer (kausar et al., 2018; palapa et al., 2018b). the schematics of direct yellow adsorption onto layered double hydroxides was shows in fig. 4. figure 3. comparison of the adsorption e�ciency direct yellow by zn/al-ldh and zn/fe-ldh figure 4. the schematic adsorption process of direct yellow onto layered double hydroxides kinetic modeling of the adsorption process provides a prediction of adsorption rates, and allows the determination of �tting rate expressions characteristic for possible reaction mechanisms. in this study, pseudo-�rst-order and pseudo-secondorder has been examined. the parameters of pseudo-�rst-order and pseudo-second-order was estimated with the aid of the nonlinear regression. the obtained value and coe�cient correlation were showed in table 1. based on coe�cient correlation both layered double hydroxides are higher for pseudo-second-order than pseudo-�rst-order. the result indicated that the adsorption table 1. kinetic parameters of adsorption direct yellow onto layered double hydroxides kinetic parameters layered double hydroxidesmodels zn-al-no3 zn-fe-no3 pseudo-�rst k1 0.0597 0.0339 order r2 0.9127 0.891 pseudo-second k2 0.0064 0.0072 order r2 0.9544 0.9176 qe 80.791 54.965 process is chemisorption (kazeem et al., 2019; hidayati et al., 2019). 4. conclusions in this study, adsorption experiment for removal direct yellow by zn/al-ldh and zn/fe-ldh. the synthesis of zn/al-ldh and zn/fe-ldh using co-precipitation method with molar ratio and obtained white and brown powder. zn/al-ldh and zn/feldh were characterized using xrd and ftir and applied as adsorbent to removal direct yellow dye in aqueous solution. the adsorption was carried out by varying time and �tted to kinetic models. the result was shows both layered double hydroxides more �tted using pseudo-second-order than pseudo-�rst-order. 5. acknowledgement author thankful to hibah tesis magister form ministry of research technology and higher education contract no. 096/sp2h/lt/drpm/2019 references daud, m., a. hai, f. banat, m. b. wazir, m. habib, g. bharath, and m. a. al-harthi (2019). a review on the recent advances, challenges and future aspect of layered double hydroxides (ldh)–containing hybrids as promising adsorbents for dyes removal. journal of molecular liquids; 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(2017); mansour (2018); park (2016)). the advantage of the naïve bayes classi�cation method is that it has a simple algorithm and works well when the data has a higher dimensional space (sequera et al. (2017); kavila et al. (2016)). however, when the input variable is a continuous variable, the gaussian distribution assumption used sometimes does not provide a satisfactory accuracy rate. the can classi�cation system can also be built based on digital images, where the input variables are the pixel values of the color of the can digital image. resti et al. (2017);resti et al. (2019a); resti et al. (2019b) used the red, green, and blue (rgb) color models, while resti et al. (2020) used the cyan, magenta, yellow, and black (cmyk) color models to represent the pixel values of the color of the can digital image, however the accuracy rate obtained is not satisfactory (resti et al. (2017); resti et al. (2019a) obtains an accuracy rate of less than 80%, whereas resti et al. (2019b); resti et al. (2020) obtains an accuracy rate of less than 50%). there is no speci�c de�nition of a minimum accuracy rate of a classi�cation system, but obtaining a better accuracy rate makes the system built more accurate, e�cient and useful. generally the researches claim the minimum accuracy rate of a classi�cation system for a satisfactory level at 85 % (arono� (1985); foody (2008); liu and an (2020)). based on this fact, it is very important to develop and modify the classi�cation system of cans waste from previous studies so that the classi�cation system has a higher accuracy rate and at least achieves more than 85% accuracy. one way to overcome this problem is to use a fuzzy approach (rastogi et al. (2019); soares and moraes (2018); aziz et al. (2016); ferreira et al. (2015); moraes (2015)). this paper discusses the classi�cation of cans using a fuzzy approach to the naïve bayes model to obtain better classi�cation results than the original naïve bayes. the validation technique used is k-fold cross validation, while the process of splitting up data and classi�cation is done with the help of r software 4.01. 2. experimental section 2.1. data the data used in this study are data of pixel values of red (x1 ), green (x2 ), and blue (x3 ) of 250 cans which are distributed into three types of cans; 29.6 % cans of type 1, 33.2 % cans of type 2, and 37.2 % cans of type 3. the pixels are obtained by capturing https://doi.org/10.26554/sti.2020.5.3.75-78 author et. al. science and technology indonesia, 5 (2020) 75-78 cans placed on conveyor belts at a speed of 0.181 m/sec where the webcam was set at an angle of 900. the statistics summary of the pixel values of each colour are presented in table 1. table 1. statistics summary of input variables statistics input variable x1 x2 x3 minimum 129.2 134.7 123.8 1st quartile 139.1 140.7 139.1 median 141.7 143.2 142.1 mean 142.9 143.4 142.4 3rd quartile 145.8 146.2 145.1 maximum 179.9 161.4 181.2 2.2. methods this study uses k-folds cross validation technique by splitting data into k=10 fold to obtain the best classi�cation model (sharma et al., 2017). this data splitting process is carried out with the help of software r 4.0.1. the initial step after having 10 fold data is to randomly select one fold data as test data from the 10 folds data where 9 folds data that are not selected as test data are used as training data. second, determine the prior probabilities, likelihood function parameters of each input variable, and the posterior probabilities of each type of can in each training data for obtained a classi�cation model using original naïve bayes (onb) as in equation (1). let x1,x2,x3 be the input variables of pixel values of red, green, and blue successively, kj be the j-th cans type, j = 1, 2, 3. probability ofkj, given x1,x2,x3 according to the bayes theorem is expressed as (ferreira et al., 2015). p(kj|x1,x2,x3) = p(x1,x2,x3|kjp(kj) p(x1,x2,x3) = p(kj)p(x1,x2,x3 3 ∏ d=1 p(xd |kj) (1) third, classify each can of observations in the test data using the onb model obtained in step 2 and create a confusion matrix as table 2 to obtain an accurate level of classi�cation as in equation (2), where tjj be the percentage of cans coming from the j-th cans type predicted exactly to the j-th cans type, whereas fjl is the percentage of the number of cans coming from the j-th cans type predicted to the l-th cans type. table 2. confusion matrix cans type cans type predicted (l-th) actual (j-th) 1st 2nd 3rd 1st t11 f12 f13 2nd f21 t22 f23 3rd f31 f32 t33 accuracyrate = t11 + t22 + t33 (2) the next step is to use a fuzzy approach such as on each input variable of each type of can in each training data to determine the fuzzy probability as in equations (3) to obtain a classi�cation model using this approach to the naïve bayes (onb) model. p(x) = ∫ 't (x)f (x)dx (3) where for each d = 1, 2, 3, f (x)4 be the probability density function of gaussian distribution, 't (x) be the membership functions of fuzzy set in this research are denoted in eq. (4) – (6). let a be the element of the domain that has the greatest membership value and b be the element of the domain that has the smallest membership value, the membership functions for dark color is 't (x) = ⎧⎪⎪ ⎨⎪⎪⎩ 1 ; x ≤ a b−x b−a ; a ≤ |x| ≤ b 0 ; x ≤ b (4) let � be the element of the domain which is the smallest value and also has the smallest membership value, b be the element of domain which is the median of data and has the greatest membership value, and c be the element of domain which is the greatest value but has the smallest membership value, the membership functions for moderate color is 't (x) = ⎧⎪⎪ ⎨⎪⎪⎩ 0 ; x ≤ a,ataux ≥ c x−a b−a ; a ≤ x ≤ bc−x c−b ; b ≤ x ≤ c (5) let � be the element of domain that has the smallest membership value and b be the element of domain that has the greatest membership value, the membership functions for light color is 't (x) = ⎧⎪⎪ ⎨⎪⎪⎩ 0 ; x ≤ a x−a b−a ; a ≤ x ≤ b 1 ; x ≥ b (6) next is to classify each can of observations on the test data using the model obtained in previous step and make a confusion matrix to obtain the classi�cation accuracy rate, and �nally analyze the classi�cation results. 3. results and discussion 3.1. the original model of naïve bayes in the onb model, the parameters of the input variables that are assumed to be gaussian distributions are estimated with maximum likelihood estimation. the estimated parameter results for the 10tℎ fold are presented in table 3. the parameters for other folds are obtained in the same way. © 2020 the authors. page 76 of 78 author et. al. science and technology indonesia, 5 (2020) 75-78 table 3. parameter gaussian distributions for the 10tℎ fold can input variable type � � � � � � 1st 153.84 8.9 151.28 6.11 142.4 9.34 2nd 145.93 4.81 148.81 4.12 147.76 2.39 3rd 146.69 5.52 147.76 4.76 145.18 4.38 in this study, the 6tℎ fold data was chosen as the test data so that the other 9 fold data as training data. implementation of the 10tℎ fold data as training data and the 6tℎ fold data as test data to equation (1) gives the classi�cation results as presented in table 4 with a classi�cation accuracy rate of 75.00%. only cans from the 2nd type have all been classi�ed correctly. the highest percentage of misclassi�cation occurs in cans from the 3rd type are classi�ed as cans of the 2nd type, which is 16.67%. table 4. classi�cation result of onb model for the 10tℎ fold original naïve % number of cans from type bayes model 1st 2nd 3rd % number of 1st 20.83 0 0 cans classi�ed 2nd 0 33.33 16.67 into can type 3rd 8.33 0 20.83 accuracy rate 75.00 % the classi�cation results of the 6tℎ fold as test data using 8 other data folds as training data for the onb model are obtained in the same way. the classi�cation accuracy rate of the onb model using the k-fold cross validation technique given in table 5 shows that the onb model has an average accuracy rate of 50.26 % with a standard deviation of 14.01%. the accuracy of this model onb can be improved signi�cantly using the fuzzy approach as presented in section 3.2. table 5. accuracy rate of onb model training testing accuracy rate fold fold of onb 1 51.85% 2 55.56% 3 29.63% 4 32.00% 5 6 50.00% 7 62.50% 8 50.00% 9 45.83% 10 75.00% average 50.26% standard deviation 14.01% 3.2. improved model of naive bayes using fuzzy approach the fuzzy membership function of each input variable is obtained using equation (4) (6) where the parameters are points with the same distance in the interval [min, max] of pixel values. in the 10tℎ fold data, the fuzzy membership function of variable x1 which has a pixel value in the interval [137.59, 167.49] is expressed by, 'd(x1) = ⎧⎪⎪ ⎨⎪⎪⎩ 1 ; x1 ≤ 137.59 147.56−x1 9.97 ; 137.59 ≤ x1 ≤ 147.56 0 ; x1 ≤ 162.50 (7) 'm(x1) = ⎧⎪⎪ ⎨⎪⎪⎩ 0 ; x1 ≤ 142.57,ataux1 ≥ 162.50 x−142.57 9.97 ; 142.57 ≤ x1 ≤ 152.54162.50−x1 9.97 ; 152.54 ≤ x1 ≤ 162.50 (8) 'l(x1) = ⎧⎪⎪ ⎨⎪⎪⎩ 0 ; x1 ≤ 157.52 x1−157.52 9.97 ; 157.52 ≤ x1 ≤ 167.49 1 ; x1 ≥ 167.49 (9) the fuzzy membership function and the parameters for other variables and fold data are obtained in the same way. the classi�cation results of the 6tℎ fold as test data and the 10tℎfold data as training data using fuzzy approach (ionbf) are presented in table 6 with an accuracy rate of 83.33 %. the percentage of misclassi�cation in each type at 4.17 % where cans from the 1st and 2nd types are classi�ed as cans of the 3rd type and cans from the 2nd as type. there is not one type of can which all of its members are classi�ed correctly as a whole. table 6. classi�cation result of ionbf model for the 10th fold ionbf model % number of cans from type 1st 2nd 3rd % number of 1st 25 0 0 cans classi�ed 2nd 0 29.17 4.17 into can type 3rd 4.17 4.17 29.17 accuracy rate 83.33% the classi�cation results of the 6tℎ fold as test data using ionbf model where 8 other fold data as training are obtained in the same way. accuracy rate of ionbf model using k-fold cross validation technique given in table 7 noted that the ionbf model has an average accuracy rate of 85.19 % with a standard deviation of 6.29 %. all accuracy rate of testing data for all training data in the ionbf model is higher than the onb model, as well as the average accuracy overall. the improvement of the average accuracy rate from onb model to ionbf of this model is 34.93%. this fact shows that the fuzzy approach on the onb model can improve the classi�cation accuracy rate. © 2020 the authors. page 77 of 78 author et. al. science and technology indonesia, 5 (2020) 75-78 table 7. accuracy rate of ionbf model training testing accuracy rate fold fold of onb 1 83.33% 2 79.17% 3 79.17% 4 79.17% 5 6 95.83% 7 83.33% 8 91.67% 9 91.67% 10 83.33% average 85.19% standard deviation 6.29% 4. conclusions in this study, the accuracy of the model was obtained as the average level of accuracy of one test data that was randomly selected using a model of 9 data fold as training data. the average accuracy of the ionbf model using cross validation technique is 85.19% with a standard deviation of 6.29 %. this accuracy level is higher than the average accuracy of the onb model which is only 50.26 % with a standard deviation of 14.01 %. the accuracy of the onb model can be improved by the fuzzy approach. a decrease in the standard deviation of 7.72 % also indicates that this model is better than the onb model. 5. acknowledgement this research was supported by dipa, university of sriwijaya, no. sp dipa-042.01.2.400953/2019, for the competitive research, no. 0015 /un9/sk.lp2m.pt/2019. references arono�, s. 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423–436 © 2020 the authors. page 78 of 78 introduction experimental section results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 2, april 2021 research paper synthesis of titanium dioxide nanotubes with different n-containing ligands via hydrothermal method cheng yee leong1, ye shen lo1, pei wen koh2, siew ling lee1,3* 1department of chemistry, faculty of science, universiti teknologi malaysia, 81310 johor bahru, malaysia2csc screen process supplies sdn bhd, 14, jalan bertam 5, taman daya, 81100 johor bahru, johor, malaysia3centre for sustainable nanomaterials, ibnu sina institute for scientific and industrial research, universiti teknologi malaysia (utm), 81300 johor bahru, malaysia *corresponding author: lsling@utm.my abstracttitanium dioxide (tio2) nanotubes (tnt) were successfully synthesized using different n-containing ligands via hydrothermalmethod. methylamine, ethylenediamine and diethylenetriamine with different ti/ligand molar ratios (1:1, 1:3, 1:5 and 1:8) wereprepared. as-synthesized tio2 without n-containing ligands were also prepared for comparison purpose. the x-ray diffractionpatterns confirmed the presence of anatase phase of tio2 in all the synthesized samples whereas the presence of sodium titanatewas only detected in the samples containing n-containing ligands. the transmission electron microscopy images also showed thatthe n-containing ligands promoted the formation of nanotubes in the anatase tio2. based on the tauc plot, the band gap energyof anatase tio2 was shifted with the addition of methylamine, ethylenediamine and diethylenetriamine. the photoluminescencespectra also showed that with the addition of sufficient amount of n-containing ligands, the intensity of photoluminescencespectrum decreased, suggesting formation of more nanotube and reduction of electron hole recombination rate. the photocatalyticperformance of all synthesized samples was determined through photodegradation of congo red under uv light for 6 hours. theresults suggested that among the synthesized materials, the sample which contained diethylenetriamine with molar ratio of 5gave the highest photocatalytic activity of 76.71% which could be attributed to successful formation of nanotube, its higher surfacerate reaction and low electron hole recombination. diethylenetriamine showed higher efficiency in assisting the formation of tio2nanotubes compared to methylamine and ethylenediamine. keywordstitanium dioxide nanotube, n-containing ligands, photocatalyst, hydrothermal, congo red received: 20 february 2021, accepted: 23 march 2021 https://doi.org/10.26554/sti.2021.6.2.67-73 1. introduction titanium dioxide (tio2) nanoparticles is examined as an inert and safe material and has been used in many applications such as pigments, sunscreen and coloring. nonetheless, tio2 only absorbs ultraviolet light due to its large band gap energy of 3.2 ev. therefore, it is desirable to reduce the band gap of anatase tio2 to be active under visible region. several approaches had been used including doping of metal and non-metal as well as modication of the surfaces (koh et al., 2017; ooi et al., 2020; ooi et al., 2016; lee et al., 2016). doping of tio2 with metals has a major drawback that the photocatalytic activity of metal doped tio2 could be inuenced by dopant concentration. while, for the doping of tio2 with non-metals, the doping into the lattice of tio2 usually resulted in the formation of oxygen vacancies in the bulk which deteriorate the visible light photocatalysis eciency in industrial applications (dong et al., 2011; li et al., 2008). as an alternative, the morphologies of tio2 photocatalysts has been intensively explored to improve its performance as a photocatalyst. compared to zero-dimensional and two-dimensional nanostructures, more attention has been paid to one-dimensional tio2 nanostructures which include nanowire, nanorod and nanotube due to its high aspect ratio, large specic surface area and excellent ionic charge transport property (lee et al., 2014). hydrothermal synthesis is a facile and preferable route for the synthesis of tio2 nanotubes since the products prepared by this method have well crystalline phase, which benets to thermal stabilityof the nanosized materials. even so, traditional hydrothermal synthesis of tio2 nanotubes often requires highly concentrated alkali such as 10 to 12 m of koh or naoh (kasuga et al., 1998). in our research group’s previous study, it showed that the synthesis of tio2 nanotubes could be done in the presence of low concentration of alkali with the assistance https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.2.67-73&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.2.67-73 leong et. al. science and technology indonesia, 6 (2021) 67-73 of n-ligand (leong et al., 2020). in that study, methylamine was used as the n-ligand, allowing the binding between the n atom of methylamine with the ti +4 of the titanate layer, hence, assisting the nanosheet to curl up, forming tio2 nanotube (leong et al., 2020). other than methylamine, both the ethylenediamine and diethylenetriamine (deta) are also the n-ligands. more n atoms can be found in these two n-ligands as compared to methylamine. since the n atom plays a major role in assisting the tio2 nanotubes formation as proven in the previous study, it is expected that ethylenediamine and deta work better than methylamine. as such, this current study is aimed to investigate the eect of dierent n-containing ligands on the formation of tio2. an attempt was made to synthesize tio2 nanotubes with dierent n-containing ligands via hydrothermal method in a xed hydrothermal condition. 2. experimental section 2.1 materials anatase tio2 powder (sigma aldrich, ≥ 99.0%), methylamine hydrochloride (sigma aldrich, ≥ 98.0%), ethylenediamine (merck, ≥ 99.0%),diethylenetriamine(merck, ≥ 98.0%), sodium hydroxide (merck, ≥ 99.0%), congo red. 2.2 methods in a typical synthesis, inside a teon bottle, 0.5 g of anatase tio2 powderwas mixed with mixture of 70 mlof 7 m sodium hydroxide and 0.419 ml ethylenediamine. the molar ratio of ti to ethylenediamine was 1:1. the mixture was stirrer vigorously (1000 rpm) for 1 h. after that, the teon bottle was transferred into stainless-steel autoclave and hydrothermally treated at 130◦c for 24 h. the obtained white precipitate was washed with 0.01 m sulfuric acid and double distilled water until ph 7 before drying at 60◦c overnight. samples with other ti to ethylenediamine molar ratio (1:3, 1:5, 1:8) was prepared with the same conditions. samples were also prepared with exactly the same method and conditions using methylamine and diethylenetriamine as the ligand in replacement of ethylenediamine. for comparison purpose, as-tio2 was prepared with the same conditions without addition of ethylenediamine. samples was labelled as xy-tnt where x is the molarratio of ligand (1,3,5,8), yis the ligand (methylamine, ethylenediamine, diethylenetriamine) and tnt is the titania nanotube. the phases and crystallinity of the samples were examined with x-ray diractometer (xrd) (bruker advance d8) with cu k𝛼 irradiation (_ = 0.15406 nm, 40 kv, 40 ma). samples were scanned in the range 2\ = 2 – 80◦ with step size 0.05◦/s. the morphology of the selected samples was conrmed with transmission electron microscopy (tem) (jeol jem-2100) operating at 200 kv. samples were dispersed in absoluteethanolandultrasonicatedfor10minutesprior to load onto carbon coated copper grid. (perkin elmer ultravioletvisible spectrometer lambda 35) was used to study the optical properties of the samples. barium sulphate was used as the reference. fixed amount of sample (2.000 ± 0.0005 g) was put into the sample holder and was scanned in the range 200 – 800 nm. band gap energy of the samples was obtained from tauc plot. it is a plot of (𝛼ha)2 against ha where 𝛼 is the absorbance, h is the planck constant and a is the velocity of light. photoluminescence (jasco, fp-8500) with an excitation of 344 nm was used to study the rate of electron-hole recombination of the samples. photocatalytic testing was carried out using 50 ml 15 ppm congo red and 0.01 g samples and irradiated under uv for 6 h. prior to reaction, adsorption was carried out to ensure the decreased of the concentration was attributed solely to photodegradation. 3. results and discussion 3.1 structural properties figure 1 illustrated the xrd patterns of as-synthesized tio2 and samples dierent n-ligands molar ratio. the xrd pattern of as-synthesized tio2 pattern conrmed the presence of anatase phase (jcpds 21-1272) in which the peaks can be found at 2\ values of 24.8◦, 37.3◦, 47.6◦, 53.5◦, 55.1◦ and 62.2◦ that corresponded to (101), (004), (200), (105), (211) and (204) crystal planes respectively. the peak positions were consistent with the standard diraction pattern of anatase tio2 with no other crystalline phase observed. a broad peak was observed at 2\ values of 28◦ in the synthesized samples that containing n-ligands. the peak represented na2ti3o7 type of sodium titanate (jcpds 31-1329). the presence of na atoms can be explained when treating the raw material with aqueous naoh solution, some ti-o-ti bonds were broken, and ti-ona and ti-oh bonds were formed (kasuga et al., 1998). it was proposed that acid treatment on the sample changed the composition in the sample from sodium titanate to hydrogen titanate through an ion exchange mechanism and aected the attributes of tnts owing to the relative amount of na and h atoms within tnt structure (ou and lo, 2007). however, there were not characteristic peak of hydrogen titanate observed in the xrd pattern. it was because the ph of the samples were washed approximately to 7 that can retard the ion exchange process so the nanotubes mostly retain their sodium titanate composition (weng et al., 2006). 3.2 morphology of the samples figure 2 showed the tem and hrtem images of the selected samples. a mixture of unreacted nanoparticles of tio2 powders and tio2 nanotubes was observed in figure 2 (e) and (f). the nanoparticles of tio2 in anatase had a spherical morphology. from the distance between the adjacent lattice fringes, the nanoparticles showed lattice spacing of d = 0.35 nm for the (101) plane of the anatase phase which was consistent with the xrd results. figure 2 (a), (b), (c) and (d) showed the tem micrograph of the samples that contained n-ligands. it can be observed that the samples both contained tio2 nanotubes that overlap each other and had constant diameter of 10 15 nm. the interspacing between the neighboring anatase of the tube © 2021 the authors. page 68 of 73 leong et. al. science and technology indonesia, 6 (2021) 67-73 table 1. synthesis conditions of dierent ligands with dierent ratio ligand ratio volume (ml) / temperature duration labelweight used (g) (°c) (hours) methylamine 1:01 0.0972 g 130 24 1 mt tnt methylamine 1:03 0.5833 g 130 24 3 mt tnt methylamine 1:05 0.9721 g 130 24 5 mt tnt methylamine 1:08 1.5553 g 130 24 8 mt tnt ethylenediamine 1:01 0.4190 ml 130 24 1 et tnt ethylenediamine 1:03 1.2580 ml 130 24 3 et tnt ethylenediamine 1:05 2.0970 ml 130 24 5 et tnt ethylenediamine 1:08 3.3550 ml 130 24 8 et tnt diethylenetriamine 1:01 0.6458 ml 130 24 1 dt tnt diethylenetriamine 1:03 1.9375 ml 130 24 3 dt tnt diethylenetriamine 1:05 3.2290 ml 130 24 5 dt tnt diethylenetriamine 1:08 5.1668 ml 130 24 8 dt tnt wall was determined to be about 0.24 nm which correspond for the plane (004) of anatase tio2. scherrer equation was then used to calculate the crystallite size of as-synthesized tio2 and samples that contained n-ligands. from the calculation, the crystallite size of assynthesized was larger than samples that contained n-ligands. it was reported that smaller crystallite size of tio2 with high surface area can increase the number of active surface sites and the surface charge carrier transfer rate in the photocatalytic reaction (carrera-lópez and castillo-cervantes, 2012). the results indicated that as-synthesized tnt has crystallite size of 31.60 nm. upon modication with either methylamine, ethylamine or diethylenetriamine surfactant, the crystallite size of the samples decreased to the range of 26.33 – 26.27 nm. this showed that the addition of these three surfactants able to reduce the crystallite size of tnt. however, comparison among the modied samples, it was noted that the amount of surfactant has insignicant eect on the crystallite size. this was because n atoms had been introduced into the lattice without changing the average unit cell dimension (sathish et al., 2005). 3.3 optical properties inordertostudytheeectofdiethylenetriamine ligandtowards the optical property of tio2 nt, the synthesized samples were subjected to analysis using dr-uv-vis spectrophotometer. the optical spectrum of the samples was depicted in figure 3. as shown in figure 3 (a), it had a peak located between range of 270 nm to 280 nm, which were associated with the hydrated tetrahedral ti species that is widely recognized as the most important ti species to provide active site for the photocatalytic activity of tio2 (lee et al., 2015; xu et al., 2015). the band gap energy was determined using tauc plot, the addition of diethylenetriamine increased the band gap energy of as-synthesized tio2 nt from 3.2 ev to 3.25 ev, 3.27 ev, 3.29 ev and 3.31 ev for 1 dt tnt, 3 dt tnt, 5 dt tnt and 8 dt tnt respectively. apparently, the band gap energy increased when the molar ratio of diethylenetriamine increased. it was reported that the decrease in particle size resulted in increased of band gap energy due to quantum size eect (avinash et al., 2016). as shown in figure 3 (b), tnt synthesized with the presence of diethylenediamine gave a similar optical spectrum when diethylenetriamine was used; there was broad peak located between range of 280 nm to 295 nm which was attributed to octahedral ti (lee et al., 2015). the addition of ethylenediamine decreased the band gap energy of as-synthesized tio2 nt from 3.2 ev to 2.95 ev, 2.93 ev, 3.03 ev and 3.13 ev for 1 et tnt, 3 et tnt, 5 et tnt and 8 et tnt respectively. in general, addition of ethylamine surfactant reduced the band gap energy of as-synthesized tio2 from uv region to visible light region. this visible light absorption could be attributed to the n atom of the surfactant which nitrogen was incorporated in tio2 lattice so the localized n 2p states were positioned above the titanium dioxide valence band and the band gap became narrow (dolat et al., 2013). as shown in figure 3 (c), an absorption peak at 320 nm was indicated in all synthesized samples except as-synthesized tio2 which was associated to anatase tio2 (xiong et al., 2017). an absorption peak at 270 nm can be found in all synthesized samples which was related to amorphous ti (cambloret al., 1993). it could be suggested that methylamine promoted the transformation of amorphous ti species crystalline anatase phase of tio2. the addition of methylamine increased the band gap energy of assynthesized tio2 nt from 3.2 ev to 3.37 ev, 3.41 ev, 3.35 ev and 3.27 ev for 1 mt tnt, 3 mt tnt, 5 mt tnt and 8 mt tnt respectively. there was no signicant inuence of the molar ratio of methylamine on the band gap energy of tio2. the increase of band gap energy of samples synthesized © 2021 the authors. page 69 of 73 leong et. al. science and technology indonesia, 6 (2021) 67-73 figure 1. xrd patterns of (a) samples with methylamine and as-synthesized tio2, (b) samples with ethylenediamine and as-synthesized tio2, (c) samples with diethylenetriamine and as-synthesized tio2 with the presence of methylamine compared to as-synthesized tio2 tnt could be due to quantum size eect (avinash et al., 2016). 3.4 photoluminescence study photoluminescence spectroscopy was carried out to study the electron hole recombination rate. from figure 4 (a), the intensity did not directly relate to the molar ratio of diethylenetriamine. 1 dt tnt has the highest intensity while 8 dt tnthas the lowestemission intensity. theresults implied that 1 dt tnt had the lowest electron-hole recombination rate while 8 dt tnt had the highest electron-hole recombination rate. compare to as-synthesized tio2, except 8 dt tnt, presence of diethylenetriamine reduced the electron-hole recombination rate of as-synthesized tio2 tnt which could be attributed to diethylenetriamine assisted in formation of nanotube. it was reported that nanotube enhanced the electron transfer to the surface hence retard the electron-hole recombination figure 2. tem and hrtem image of (a), (b) 5 dt tnt, (c), (d) 3 mt tnt, and (e), (f) as-synthesized tio2 rate (sunetal.,2008). additionofexcess surfactant (ti: deta = 1: 8) resulted in increasing of electron-hole recombination rate. this could be due to excess of surfactant acted as recombination center. from figure 4 (b), the lowest intensity of the peak was 1 et tnt and the highest intensity of the peak was 8 et tnt. the intensity of the peak of 1 et tnt was lower compared to as-synthesized tio2 could be attributed to more nanotube was formed which retarded the electron-hole recombination rate (sun et al., 2008). on the other hand, further addition of diethylenediamine increased the emission intensity even though more nanotube was formed. a possible explanation for increased emission intensity could be ascribed to more electrons were excited from valance band to conduction band (fang et al., 2015). from figure 4 (c), there was a decrease in uorescence intensity with an increase in the amount of methylamine added to the anatase tio2. it can be explained that the formation of more nanotube as evidence from the tem images, reduced the electron-hole recombination rate. alternatively, the nitrogen facilitated the separation of photo-generated electron–hole pair for the formation of oxygen vacancies that can inhibit the recombination of photo-generated charge to some extent (irie et al., 2003). the intensity for 5 mt tnt was exactly the same 8 mt tnt. this indicated that the reduction in photoluminescence intensity had achieved saturation without further reduction. from figure 4 (d), 3 mt tnt had the lowest intensity which indicated it had lowest electron hole recombination rate but it can decrease the surface reaction rate and lower the photocatalytic activity (wojcieszak et al., 2013). 3.5 photocatalytic testing from table 2, the photocatalytic activity for 5 dt tnt was higher compared to as-synthesized tio2. it can be explained basedonthetemmicrographs inwhichmoretio2 nanotubes © 2021 the authors. page 70 of 73 leong et. al. science and technology indonesia, 6 (2021) 67-73 table 2. photocatalytic activities of samples prepared with and without diethylenetriamine temperature duration sample q1 (ppm) q2 (ppm) photocatalytic (◦c) (hours) eciency (%) 130 24 as-synthesized tio2 12.9 5.91 54.2 130 24 1 dt tnt 12.76 5.16 59.6 130 24 3 dt tnt 13.26 4.94 62.7 130 24 5 dt tnt 13.29 3.1 76.7 130 24 8 dt tnt 12.98 4.79 63.1 table 3. photocatalytic activities of samples prepared with and without ethylenediamine temperature duration sample q1 (ppm) q2 (ppm) photocatalytic (◦c) (hours) eciency (%) 130 24 as-synthesized tio2 12.9 5.91 54.2 130 24 1 et tnt 13.68 6.87 49.8 130 24 3 et tnt 13.43 5.96 55.6 130 24 5 et tnt 12.62 3.61 71.4 130 24 8 et tnt 12.16 6.9 43.2 were produced with the addition of diethylenetriamine compared to as-synthesized tio2. diethylenetriamine might assist the scrolling of the intermediate nanosheet to form nanotube in which higher degree of nanotubes formation enhanced the photocatalytic activity of tio2. besides, the results showed that the photocatalytic eciency increased when the molar ratio of diethylenetriamine increased until a certain extent. this is because appropriate amount of diethylenetriamine and appropriate temperature were benecial to increase excited electrons, and thus improve the photocatalytic activity. even though 5 dt tnt did not have the lowest electron-hole recombination rate (it has the second lowest emission intensity as shown in the photoluminescence spectra in figure 4 (a)), but it has the best photocatalytic activity. this could be because it had faster surface reaction rate than the recombination rate that resulted in a net increase of photocatalytic eciency. it was reported that both recombination rate and surface reaction rate were the factors to determine the photocatalytic activity. fromtable3, subsequent increaseofmolarratioofethylenediamine from 1 to 5, the photocatalytic activity of tio2 nanotubes was increased. 5 ettnthas the highest photocatalytic eciency of 71.4%. even though 5 et tnt has relatively higher emission intensity compared to 1 et tnt and 3 et tnt,but theobtainedphotocatalyticeciencywashigherthan the later. the reason could be the surface reaction rate at 5 et nt was very high which overcome the eect of electron-hole recombination and resulted in a better activity. on the other hand, the photocatalytic activity decreased after the ethylenediamine molar ratio used was higher than 5. this could be deduced that addition of excess ethylenediamine acted as recombination centre and the fate of electron-hole recombination rate was more prevailed. from table 4, samples contained methylamine had higher photocatalytic activity compared to as-synthesized tio2 and 3 mt tnt had the highest photocatalytic eciency. fromthetemmicrograph, thecrystallitesizeofas-synthesized tio2 was larger than 3 mt tnt. it was reported that the average diusion path length of charge carrier from the bulk to the surface became longer in a bigger tio2, which will result in deep trapping of charge carriers, leading to lower photocatalytic activity. in addition, reduction in crystallite size which resulted in larger surface area can increase the available surfaceactive sites and consequently resulting in higher photocatalytic eciency. therefore, it was believed that 3 mt tnt has the highest photocatalytic activity was attributed smaller crystallite size that resulted in faster charge transfer and more surfaceactive site. 4. conclusions the synthesis of tio2 nanotubes were successfully performed via hydrothermal method using of dierent n ligands. all the samples consisted of white powder which indicated that the addition of n ligands did not aect the color of tio2. the samples were characterized successfully to study their physical and chemical properties. the xrd analysis indicated the presence of anatase tio2 and sodium titanate in the samples that contained n ligands. from the tem analysis, more nanotubes were formed in 3 mt tnt and 5 dt tnt compared to as-synthesized tio2. from the tauc plots, there was a shifting in the band gap energy of the samples that contained n ligands. photoluminescence spectrum also showed there was a decrease in the intensity from the spectrum with the addition of certain n ligand until certain extent which can relate to the © 2021 the authors. page 71 of 73 leong et. al. science and technology indonesia, 6 (2021) 67-73 table 4. photocatalytic activities of samples prepared with and without methylamine temperature duration sample q1 (ppm) q2 (ppm) photocatalytic (◦c) (hours) eciency (%) 130 24 as-synthesized tio2 12.9 5.91 54.2 130 24 1 mt tnt 13.07 4.16 68.2 130 24 3 mt tnt 12.82 3.93 69.4 130 24 5 mt tnt 13.27 5.24 60.5 130 24 8 mt tnt 12.67 5.26 58.45 figure 3. dr-uv-vis spectra of (a) methylamine, (b) ethylenediamine, and (c) diethylenetriamine electron hole recombination rate. the photodegradation of congo red also gave result that samples with n ligands with optimum molar ratio had higher photocatalytic activity than as-synthesized tio2. the photocatalytic eciency for each of the synthesized samples was determined through photodegradation of congo red under dark condition and uv irradiation for 6 hours. from the results, 5 dt tnt (76.7%), 5 et tnt (71.4%) and 3 mt tnt (69.4%) showed the highest photocatalytic eciency among their series and had higher photocatalytic eciency than as-synthesized tio2 (54.2%). in conclusion, titanium dioxide nanotube was successfully synthesized via hydrothermal method in this study. 5 dt tnt was the best photocatalyst in the photodegradation of congo red with photocatalytic activity of 76.71%. methylamine, ethylenefigure 4. photoluminescence spectra of titania nanotube synthesized with (a) diethylenetriamine, (b) ethylenediamine, (c) methylamine, and (d) comparison of selected samples with highest activities diamine and diethylenetriamine played an important role to assist in the formation tio2 nanotube. diethylenetriamine showed higher eciency in assisting the formation of tio2 nanotubes compared to methylamine and ethylenediamine. 5. acknowledgement authors are whole-heartedly appreciated the nancial support given by ministry of higher education, malaysia (mohe) for the fundamental research grant scheme (reference no.: frgs/ 1/2019/stg07/utm/02/12). references avinash, b. s., v. s. chaturmukha, h. s. jayanna, c. s. naveen, m. p. rajeeva, b. m. harish, s. suresh, and a. r. lamani (2016). eect of particle size on band gap and dc electrical conductivityof tio2 nanomaterial. aipconference proceedings, 1728; 20426 camblor, m., a. corma, and j. pérez-pariente (1993). synthesis of titanoaluminosilicates isomorphous to zeolite beta, active as oxidation catalysts. zeolites, 13(2); 82–87 © 2021 the authors. page 72 of 73 leong et. al. science and technology 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mazur (2013). correlation of photocatalysis and photoluminescence eect in relation to the surface properties of tio2:tb thin films. international journal of photoenergy, 2013; 1–9 xiong, g., q. jia, y. cao, l. liu, and z. guo (2017). the eect of acid treatment on the active sites and reaction intermediates of the low-cost ts-1 in propylene epoxidation. rsc advances, 7(39); 24046–24054 xu, l., d.-d. huang, c.-g. li, x. ji, s. jin, z. feng, f. xia, x. li, f. fan, c. li, and p. wu (2015). construction of unique six-coordinated titanium species with an organic amine ligand in titanosilicate and their unprecedented high eciency for alkene epoxidation. chemical communications, 51(43); 9010–9013 © 2021 the authors. page 73 of 73 introduction experimental section materials methods results and discussion structural properties morphology of the samples optical properties photoluminescence study photocatalytic testing conclusions acknowledgement article http://sciencetechindonesia.com article history received: 21 november 2016 received in revised form: 22 january 2017 accepted: 3 february 2017 doi: 10.26554/sti.2017.2.2.50-55 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 50-55 synthesis and characterization of metal oxides supported keggin type polyoxometalate rb2k2[γ-h2siv2w10o40].nh2o eiffel ostan jeski gultom1*, aldes lesbani1 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author email: eiffelgultom@gmail.com abstract synthesis of material based on polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o with sio 2 , tio 2 , zrocl 2 , and tacl 5 was carried out to form rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-sio 2 , rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-tio 2 rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-zrocl 2 and rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-tacl 5 . materials from preparation were characterized through functional group analysis using ft-ir spectrophotometer, crystallinity analysis using xrd and surface photograph analysis using sem. the results show that material rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o was successfully loaded with sio 2 , zrocl 2 and tacl 5. based on sem photo rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 otio 2 and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-zrocl 2 were the best material from preparation base on the homogeneity particle distribution. the ft-ir spectrum shows specific wavenumber for nanomaterial rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-tio 2 in the range 455-910 cm-1 and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o zrocl 2 in the range 393.48-1404 cm-1. xrd pattern for material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-tio 2 and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-zrocl 2 show there is a difference between polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o, tio 2 and zrocl 2. sem photo analysis of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-tio 2 and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o-zrocl 2 showed that material polyoxometalate with support has a diameter size of particle above 100 nm. keywords: rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o, polyoxometalate, sio 2 , tacl 5 , tio 2 , zrocl 2 . introduction synthesis, modification, and preparation of inorganic material are still developed until this year. various inorganic materials such as metal oxides (wang et.al, 2017), zeolites (dehghan and anbia, 2017), layer materials (hanifa and palapa, 2016), inorganic complexes (ramdass et.al, 2017), organometallic compounds (pettinari, et.al, 2016) are widely used in many aspects of our life. these materials are also essential for an industrial processes such as catalysts, ion exchanges, membranes, adsorbents, and sensors. among these materials, inorganic cluster such as polyoxometalates compounds is another class of unique and specific material due to the acid base and redox properties (genovese and lian, 2017). polyoxometalates are metal-oxygen inorganic clusters with high adicity properties, redox properties, and high solubility due to the flexibility of metal exchange of heteroatom and addenda atom. polyoxometalates have several structures such as keggin, dawson, anderson, and also lacunary polyoxometalates (gao et.al, 2017). on the other hand, this material is important for industrial catalysis and has been applied in industrial organic synthesis and transformation of various functional groups. thus the development of this material is still developed until this decade. the developing of polyoxometalates can be reached by addenda/heteroatom metal exchange to form novel polyoxometalates or modification such as grafting (yong et.al, 2016), sol-gel (tambunan and mohadi, 2017), or impregnation by other metal oxides (dizaji et.al, 2017). the aim of these research is to obtain polyoxometalates with high acidity properties, high surface area, and low morphology size. thus application as a catalyst for many organic reactions can be facile. metal oxides were used as support for polyoxometalate in order to obtain high surface area and low morphology properties such as titanium, silica, and alumina. this modification method is an easy and simple way to get advantage properties of polyoxometalates. in this research, various metal oxides such as silica, titanium, zirconium, and tantalum have been used as a support of polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. polyoxometalate rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o is vanadium substituted keggin type polyoxometalate. we expected that modification of this polyoxometalate could obtain unique properties of this material. polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o supported silica, titanium, zirconium, and tantalum was characterized using ftir spectroscopy, powder x-ray analysis and identification of surface morphology by sem. experimental section materials and equipment chemicals were used in this research from merck and sigma aldrich such as sodium metasilicate, sodium tungstate, hydrochloric acid, potassium chloride, potassium carbonate, sodium metavanadate, rubidium chloride, cyclohexane, acetone, etanol, ammonia, silica dioxide, titanium dioxide, zirconium oxo chloride, and tantalum pentachloride. ftir spectrum was recorded using shimadzu ftir prestige-21 using kbr pellet and scanning wavenumber from 300-4000 cm-1. xrd powder pattern was obtained from shimadzu labx type-6000 with scanning speed one deg.min-1. sem photograph was obtained from sem jeol jed-2300. gultom et al. 2017/science & technology indonesia 2 (2) 2017:50-55 © 2017 published under the term of the cc by nc sa 4.0 licence 51 synthesis rb2k2[γ-h2siv2w10o40].nh2o (nakagawa et.al, 2005) polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o was synthesis from k 8 [β 2 -siw 11 o 39 ]14h 2 o. sodium metavanadate 0.5 m was obtained by dissolving sodium meta vanadate in hot water (solution a). polyoxometalate k 8 [β 2 -siw 11 o 39 ]14h 2 o (10 g) was mixed with 35 ml of hydrochloric acid 1m (solution b). solution a was added quickly to solution b with gentle stirring and the solution to be yellow. into these solutions, rubidium chloride (5) was added, and the solution was mixed for 15 minutes to form yellow crystals. yellow crystals were vacuum filtered. the crystals were dissolved in water, and remaining crystals were removed by filtration. the solution was vacuum concentrated to form yellow crystals of rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. characterization was conducted using ftir, xrd, and sem analyses. preparation of rb2k2[γ-h2siv2w10o40].nh2o/sio2 (kim et.al, 2006) polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (1g) was dissolved with 50 ml methanol. silica dioxide (2.5 g, 24o mesh) was added into polyoxometalate solution and solution was stirred for 30 minutes. the solution was kept for 24 hours and concentrated by vacuum. the solid material was washed with acetone and dried at 110 oc. preparation of rb2k2[γ-h2siv2w10o40].nh2o/tio2 (pozniczek et al. 2006) preparation of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tio 2 was carried out with slight modification from pozniczek. titanium oxide (1 g) was mixed with ethanol (50 ml) and into the solution was added rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (1g). the solution was heated at 50 oc for 45 minutes. the solid material was formed after cooling solution and was washed with acetone. material was dried at 110 oc for 24 hours to form rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tio 2 preparation of rb2k2[γ-h2siv2w10o40].nh2o/zrocl2 (devassy et al. 2002) procedure for preparation of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ zrocl 2 was adopted from devassy and was modified as follow. polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (1g) was dissolved in methanol (10 ml) (solution a). zirconium oxo chloride (2.5 g) was mixed with ammonia (10 ml) (solution b). solution a was mixed with solution b with slowly stirring at 50 oc for 15 minutes. the solution was centrifuged at 15,000 rpm for 5 minutes to form the solid material of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/zrocl 2 . materi rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tacl 5 al was washed with acetone and dried at 110 oc for 24 hours. preparation of rb2k2[γ-h2siv2w10o40].nh2o/tacl5 (xu et al. 2008) polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (0.5 g) was dissolved in ethanol (4 ml) and water (2 ml) was added into these solutions (solution a). tantalum pentachloride (0.6 g) was mixed with ethanol (5 ml) (solution b). solution b was mixed with solution a with slowly stirring for 1 hour. the solution was kept for 30 oc overnight to form gel. gel was heated at 130 oc for 1 hour to form a solid material of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ tacl 5 . the material was kept at 110 oc overnight to obtain rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tacl 5 . characterization of metal oxides supported rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. characterization of metal oxides supported polyoxometalate was carried out using the identification of functional groups by ftir, x-ray powder analysis, and surface morphology analysis by sem. results and discussion polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o was synthesized from polyoxometalates k 8 [β 2 -siw 11 o 39 ].14h 2 o and k 8 [γ-siw 11 o 39 ].14h 2 o, thus comparison of ftir spectrum of these compounds is needed as shown in figure 1. figure 1 shows ftir spectrum of k 8 [β 2 -siw 11 o 39 ].14h 2 o (a), k 8 [γ-siw 11 o 39 ].14h 2 o (b) and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (c). all these keggin type polyoxometalates have a similar vibration at wavenumber in the range 700-1100 cm-1. the main vibration of these polyoxometalate is si-o (at 700-720 cm-1), w-oc-w and w-oe-w (at 800-880 cm-1), and w=o (at 900-920 cm-1) (nakagawa and mizuno, 2007). wavenumber at 3300 cm-1 is appeared in all ftir spectra in figure 1 due to water content. there are no significant changes in vibration of these three polyoxometalates. thus polyoxometalate rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o is characterized using x-ray analysis. polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o were analyzed using x-ray analysis as shown in figure 2. there are sharp diffraction peaks at 2θ value 26 deg, and 28 deg, which is contributed from crystalline substituted keggin polyoxometalate. furthermore, polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o was identified by sem to know the morphology of these compound as shown in figure 3. figure 3 showed that polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o has a uniform with block shape. the particle size of rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o can be determined from figure 3. the results show compound rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o has particle size distribution 1000 nm. this results indicated that figure 1. ftir spectrum of k 8 [β 2 -siw 11 o 39 ].14h 2 o (a), k 8 [γ-siw 11 o 39 ].14h 2 o (b) and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (c). figure 2. xrd powder pattern of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. gultom et al. 2017/science & technology indonesia 2 (2) 2017:50-55 © 2017 published under the term of the cc by nc sa 4.0 licence 52 compound rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o is needed to support with a metal oxide. metal oxides such as silica, titanium, zirconium, and also tantalum chloride will be used as a support of rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. in the first experiment, silica dioxide was used as a support of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o and the materials were characterized using ftir analysis as shown in figure 4. figure 4c showed that polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o/sio 2 has broaden peaks in the wavenumber range 600-1000 cm-1, which is attributed from a support agent. although ftir spectrum of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/sio 2 was broaden but vibration of w-oc-w and w-oe-w is still appeared around 900-1000 cm-1. that vibrations are clue for silica oxide successfully supported polyoxometalate. further characterization was conducted using xrd and powder diffractogram is presented in figure 5. diffraction of material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/sio 2 as shown in figure 5c has different with both rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o and sio 2 as starting materials. diffraction appeared at 18 deg, 21 deg, 24 deg, and 28 deg. peaks at 18 deg and 21 deg are probably come from silica and 24 deg, and 28 deg comes from polyoxometalate, which was shifted to lower diffraction. this results indicated increasing crystallinity of material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o/sio 2 . thus novel properties of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/sio 2 is expected. further characterization was conducted using sem. the results identification of morphology using sem is shown in figure 6. figure 6 showed that material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ sio 2 has uniform shape, but small aggregation appeared. calculation of particle size revealed that material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o/sio 2 has particle size 2200 nm, which was higher than rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. for comparison of silica oxide as support thus titanium oxide was used as support for rbfigure 3. sem photograph of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o. figure 4. ftir spectrum of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), sio 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/sio 2 (c). figure 5. xrd powder pattens of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), sio 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/sio 2 (c). figure 6. sem photograph of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ sio 2 figure 7. ftir spectrum of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), tio 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 . gultom et al. 2017/science & technology indonesia 2 (2) 2017:50-55 © 2017 published under the term of the cc by nc sa 4.0 licence 53 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o to form rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o/tio 2 . spectrum ftir material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 is presented in figure 7. ftir spectrum in figure 7c for material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o/tio 2 looks similar with spectrum ftir for rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/sio 2 in figure 4c. wavenumber at 700-1000 cm-1 was broad probably due to the interaction of metal oxides both silica and titanium. the vibration of polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/sio 2 also appeared at wavenumber in the range 900-1000 cm-1, which was attributed to w-oc-w and w-oe-w vibrations. further characterization using xrd toward rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 is shown in figure 8. figure 8 showed xrd powder pattern of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ]. nh 2 o (a), tio 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tio 2 (c). diffraction of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 as shown in figure 8c has the main diffraction in the range of 20-30 deg, which was attributed to titania and polyoxometalate. another diffraction also appeared at 35-48, 52-57, and 62 deg. this pattern is quite different with silica as support. probably titanium oxide was dispersed on the surface of polyoxometalate. to know this phenomenon then sem analysis was conducted and the sem image of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 is shown in figure 9. sem photograph in figure 9 showed although uniform shape appeared, but small aggregation was formed. calculation of particle size resulted in the size particle 660 nm, which was smaller than polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/sio 2 . titanium and silica have different properties thus the results of support material was also different properties. to know the support properties thus experiment was conducted using zirconium. this experiment used zirconium oxychloride. this support quite different with silica and titanium due to chloride atom include in the support structures. the characterization for compound rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/zrocl 2 and starting materials is presented in figure 10. the interesting results were found that although zirconium different with silica and titanium but ftir spectrum is similar to all support in which peaks at wavenumber 700-1000 cm-1 is broad. the properties of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/zrocl 2 is then explored through xrd powder pattern as shown in figure 11. the results of xrd powder pattern as shown in figure 11c for rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/zrocl 2 indicated that that material has high crystallinity than silica and titanium as support. there are diffraction peaks at several areas i.e. less than 10 deg, 15-18 deg, and 25-33 deg. diffraction of zirconium and polyoxometalate was overlapped. diffraction at 8 deg is new diffraction which was probably due to oxide and chloride interaction with polyoxometalate, and this diffraction is not found for silica or titanium as supports. characterization using sem for material rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/zrocl 2 as shown in figure 12 is also interesting due to equal portion aggregation and uniform shapes. particle size calculation showed that material rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/zrocl 2 has particle size 220 nm. this particle size is widely different with polyoxometalate and other supports. to investigate the difference between pure oxides (silica and titanium), mixture oxide (zirconium), thus no oxide was used as support. tantalum chloride was used as support for polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o and analysis of ftir toward rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tacl 5 is shown in figure 13. ftir spectrum of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tacl 5 (b) in figure 13 showed that similar results were found between oxide, mixture oxide and non-oxide. wavenumber at 700-1000 cm-1 was broad similar with the use of silica, titanium, and zirconium as supports. further characterization using xrd and the pattern is shown in figure 14. diffraction of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tacl 5 revealed that there was a sharp peak at diffraction 26 deg and broad peaks at 8-12 deg. this results indicated the use of metal chloride support could create a material with different properties than oxide or mixture oxide supports. identification using sem to material rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/tacl 5 as shown in figure 15 resulted in particle size 330 nm. this size is smaller than polyoxometalate rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o. thus all experiment shows the diffigure 8. xrd powder patten of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), tio 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tio 2 (c). figure 9. sem photograph of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ tio 2 . figure 10. ftir spectrum of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), zrocl 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/zrocl 2 . gultom et al. 2017/science & technology indonesia 2 (2) 2017:50-55 © 2017 published under the term of the cc by nc sa 4.0 licence 54 ferent type of supports can create material with unique chemical and physical properties conclusion metal oxides supported polyoxometalate rb2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o were successfully conducted using tio 2 , zrocl 2 , tacl 5 dan sio 2 . the various form and sizes were obtained on supported polyoxometalate with size distribution particles more than 100 nm. acknowledgement we thanks to kemenristekdikti republik indonesia for supporting this research through” hibah kompetensi“ 2015-2016. references dehghan. r., anbia. m. (2017). zeolites for adsorptive desulfurization from fuels: a review. fuel processing technology, 167, 99-116. devassy. b.m, halligudi. s.b, hedge. s.g, halgeri. a.b, lafebvre. f. (2002). 12-tungstophosphoric acid/zirconia-a highly active stable solid acid-comparison with a tungstated zirconia catalyst. chemical communications, 1074-1075. dizaji. a.k., mortaheb. h.r., mokhtarani. b. (2017). preparation of supported catalyst by adsorption of polyoxometalate on graphene oxide/reduced graphene oxide. materials chemistry and physics, 199, 424-434. gao. y., eghtesadi. s.a., liu. t. (2017). chapter two-supramolecular structures formation of polyoxometalates in solution driven by counterion-macroion interaction. advances in inorganic chemistry, 69, 29-65. genovese. m., lian. k. (2017). 6-polyoxometalates: molecular metal oxide clusters for supercapacitors. metal oxides in supercapacitors (a volume in metal oxides), 133-164. hanifa. y., palapa. n.r. (2016). mg/al double layer hydroxides: intercalation with h 3 [α-pw 12 o 40 ].nh 2 o. science and technology indonesia, 1, 16-19. kim. h. j, shul. y. g, and han. h. (2006). synthesis of heteropolyacid (h 3 pw 12 o 40 )/sio 2 nanoparticles and their catalytic properties. applied catalysis a: general, 299, 46-51. nakagawa. y., mizuno. n. (2007). mechanism of [γ-h 2 siv 2 w 10 o 40 ]4 catalyzed epoxidation of alkenes with hydrogen peroxide. inorganic chemistry, 46,5, 1727-1736. nakagawa. y., uehara. k., mizuno. n. (2005). reactivity of bis(µ-hydroxo)divanadium site in γ-h 2 siv 2 w 10 o 40 4with hydroxo compounds. inorganic chemistry, 44, 24, 9068-9075. pettinari. c., pettinari. r., marchetti. f. (2016). chapter four-goldfigure 11. xrd powder patten of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), zroclo 2 (b), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/zrocl 2 (c). figure 12. sem photograph of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/ zrocl 2 . figure 13. ftir spectrum of of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o (a), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tacl 5 (b). figure 14. xrd powder patten of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o (a), and rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ] .nh 2 o/tacl 5 (b). figure 15. sem photograph of rb 2 k 2 [γ-h 2 siv 2 w 10 o 40 ].nh 2 o/ tacl 5 . gultom et al. 2017/science & technology indonesia 2 (2) 2017:50-55 © 2017 published under the term of the cc by nc sa 4.0 licence 55 en jubilee for scorpionates: recent advances in organometallic chemistry and their role in catalysis. advances in organometallic chemistry, 65, 175-260. pozniczek. j, lubanska. a, micek-llnicka. a, mucha. d, lalik. e, bielanski. a. (2006). tio 2 and sio 2 supparted well-dawson heteropolyacid h 6 pw 18 o 62 as the catalyst for etba formation. applied catalysis a: general, 298, 217-224. ramdass. a., sathish. v., babu. e., velayudham. m., thanasekaran. p., rajagopal. s. (2017). recent developments on optical and electrochemical sensing of copper(ii) ion based on transition metal complexes. coordination chemistry reviews, 343, 278-307. tambunan. o.r., mohadi. r. (2017). preparation of polyoxometalate compound (nh 4 ) 6 [β-p 2 w 18 o 62 ]/sio 2 by sol gel method and its characterization. science and technology indonesia, 2, 1-8. wang. g., yang. y., han. d., li. y. (2017). oxygen defective metal oxides for energy conversion and storage. nanotoday, 13, 23-39. yong. m., kim. d.s., lee. t.j., lee. s.j., lee. k.g., choi. b.g. (2016). polyoxometalate-grafted graphene nanohybrid for electrochemical detection of hydrogen peroxide and glucose. journal of colloid and interface science, 468, 51-56. _goback title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 3, july 2020 research paper transesterification reaction from rice bran oil to biodiesel over heterogeneous base calcium oxide nanoparticles catalyst nur fatin sulaiman1, abdul rahim yacob1, siew ling lee1,2* 1department of chemistry, faculty of science, universiti teknologi malaysia, 81310 johor bahru, malaysia 2centre for sustainable nanomaterials, ibnu sina institute for scientific and industrial research, universiti teknologi malaysia, 81310 johor bahru, malaysia *corresponding author: lsling@utm.my abstract this study focuses on the development of an alkaline earth metal oxide, calcium oxide (cao) as heterogeneous base catalyst for biodiesel production. the intention for this study is to explore potential for the transformation of commercial calcium carbonate, cm-caco3 into cao nanoparticles and further used as a heterogeneous base catalyst in single step transesterification reaction from rice bran oil to biodiesel. the prepared cao was calcined under 10−3 mbar vacuum, at temperatures ranging from 100°c to 700°c. tga-dta results revealed that the cm-caco3 must be calcined above 600°c in order to form cao. this is in accordance with ftir results which specified the complete formation of cao at 700°c. xrd revealed that the rhombohedral caco3 and hexagonal ca(oh)2 had completely been disappeared, leaving only crystalline cubic cao at 700°c. interestingly, the larger bet surface area (11.5 m2g−1) and highest basicity (1.959 mmol/g) were observed for cao calcined at 700°c (cao-700). the cao-700 nanoparticles were designated as a catalyst for the transesterification reaction of rice bran oil to give biodiesel. nmr and gc-fid results further confirmed the successful formation of biodiesel using cao-700 as catalyst. keywords heterogeneous catalyst; nanoparticles; biodiesel; transesterification received: 14 june 2020, accepted: 13 july 2020 https://doi.org/10.26554/sti.2020.5.3.62-69 1. introduction the physicochemical characteristics of a heterogeneous catalyst depend on their preparation techniques and the primary treatment process. there are many of research techniques are available to produce solid base catalyst such as hydration dehydration method (aziz et al. (2012); yacob and sulaiman (2012)), sol gel (corrêa et al. (2020)) and chemical vapor deposition (cvd) methods (knözinger et al., 2000). in general, physical and chemical properties such as surface area, particle size, morphology and basicity would a�ect each of catalytic activity. the signi�cance of heterogeneous base catalysts also became recognized for their environmentally sustainable qualities. much signi�cant progress in catalytic materials and solid base-catalyzed reactions has been made over the past two decades (hattori, 2001) it was reported by hattori (2001), a strong basic strength of carbonate-free metal oxide surfaces could be developed after a high-temperature treatment. surface defect that was detected by nitrogen adsorption analysis demonstrated important heterogeneous catalytic sites that could enhance the reactivity of each reaction (boro et al., 2012). as a result, the larger surface area implied good reactivity. alkaline earth metal oxides including calcium oxide, cao has basic characteristics as its oxides provide basic alkaline solutions when mixed with water. by transforming the basic oxide to hydroxides, the proton was transmitted from water to basic oxide. alternatively, the solid basic oxides donated their electron pair to the reactants. it was documented that the alkaline earth metal oxide acted as a brönsted base, while the water functioned as a brönsted acid. in the biodiesel production, transesteri�cation reaction is the most widely studied utilizing alkaline earth metal oxide as solid base catalyst (mazaheri et al. (2018); dawood et al. (2018); shan et al. (2016)). biodiesel as one of the renewable energies can be produced from vegetable oils or animal fats. it consists of blend of longchain alkyl esters such as methyl esters, which are used without modi�cation to the diesel engine as an alternative for petroleum oil. by using above resources, this biodiesel consisting of fatty acid alkyl ester is generally produced by transesteri�cation reaction. there are number of techniques to perform this reaction including supercritical process, common batch process, ultrasonic technique and microwave method (rathnam et al. (2020); hakim et al. (2019); sharma et al. (2019)). this present study focused on the preparation of cao nanoparticles from commercial calcium carbonate, cm-caco3 under https://doi.org/10.26554/sti.2020.5.3.62-69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 vacuum atmosphere of 10−3 mbar at 100 to 800°c by thermal decomposition process. the basicity of the cao nanoparticles was examined using back-titration method in order to investigate the relationship between basicity and calcination temperature. the prepared cao nanoparticles were then used for the transesteri�cation of rice bran oil to biodiesel as a heterogeneous base catalyst. rice bran oil has been selected as it is unconventional, low-cost and low-grade vegetable oil that does not have much competition for food requirement. 2. experimental section 2.1 materials in this research, the chemical reagents were used such as commercial calcium carbonate, caco3, hydrochloric acid, hcl, sodium hydroxide, naoh, methanol, ch3oh and n-hexane, c6h14 with molecular weight 100.09 g/mol, 36.46 g/mol, 40.00 g/mol, 32.04 g/mol and 86.07 g/mol, respectively. all chemical reagents were purchased from qrëc. the rice bran oil, acquired from the local store was used for the transesteri�cation reaction. 2.2 catalysts preparation calcium oxide, cao nanoparticles were prepared using thermal decomposition method under vacuum atmosphere at various calcination temperatures ranging 100 to 800 ºc. the samples were labeled as cao-100 to cao-800 according to their calcination temperature. approximately 0.4 g of the commercial caco3 powder was inserted in a quartz tube attached to vacuum line system. cm-caco3 precursor was calcined at 100 to 800 ºc in 10-3 mbar vacuum for 2 hours to produce about 0.2 g of cao sample. the basicity of cao nanoparticles was determined via back-titration method. for this purpose, cao (100 mg) was dissolved in 10 ml of distilled water. after left for 24 hours, the slurry was obtained and then centrifuged. neutralization of the resulting solution was performed using 0.05 m hcl (10 ml). finally, titration with phenolphthalein as an indicator was carried out using naoh (0.02 m) for the remaining acid (yacob and sulaiman, 2012). 2.3 catalysts characterizations the prepared cao samples were characterized by using thermogravimetric analysis–di�erential thermal analysis (tga-dta), fourier transform infrared (ftir), x-ray di�raction (xrd), �eld emission scanning electron microscopy (fesem), energy dispersive x-ray (edx) and nitrogen adsorption analysis (na). the decomposition of caco3 was studied from tga-dta analysis using mettler-toledo q100 instrument. about 15 mg sample was placed in a ceramic crucible and heated at temperature of 60 to 1000 ºc at 15 ºc/min with the �ow rate 50 ml/min of nitrogen gas. tga analysis was performed to con�rm the optimum activation temperature in the preparation of cao. next, fourier transform infrared spectroscopy (ftir) technique (wavenumber from 4000 to 400 cm−1) from shimadzu 8300 was used to identify the functional groups (cm-caco3 and cao samples). xrd analysis was carried out to examine the crystallinity degree, crystal structure and crystallite size of caco3 and the prepared cao samples. the xrd di�ractograms were obtained on a siemens d5000 powder instrument using cu-k� radiation (� = 0.15148 nm; kv = 40; ma = 40) with the 2� range from 10° to 90°. monosorb surface area analyzer model was used to evaluate the surface area of the prepared cao samples. prior to the analysis, powder sample (0.1 g) was degassed at 120 °c for 2 hours by vacuum pump to cool down the sample at room temperature. this treatment was performed to remove adsorbed gases and dead space. besides, fesem was used to examine the surface morphology, particles size and shape on the surface of cao samples via zeiss supra 35 vp scanning electron microscope. the cao samples were placed on the carbon dual-sided tape aluminum stub in a small vacuum chamber. all the cao samples were coated with gold before the fesem analysis. the elemental composition of the samples was con�rmed through edx analysis. 2.4 catalytic transesteri�cation reaction in the catalytic transesteri�cation reaction, the prepared cao (0.1 g) together with 15.0 g of methanol and 10.0 g of rice bran oil were added into a two-neck round bottle �ask. the mixture was re�uxed at 65 ± 5 °c for 30 min, followed by cooling process at ambient temperature. the mixture was then centrifuged at 5000 rpm for 10 min to separate the solid catalyst from the solution. three layers were obtained which consisted of an excess of methanol (top layer), a biodiesel (middle layer) and cao with glycerol (bottom layer). the �rst and second layers were collected and placed into a separating funnel in order to separate the biodiesel and methanol. the biodiesel was collected for further characterization. 2.5 product analysis the quantitative production of biodiesel was identi�ed by nuclear magnetic resonance (nmr). methyl esters derived from the transesteri�cation reaction were analyzed by 1h nmr in cdcl3 using tms as internal standard. the ratio between the peak of 3.6 ppm from methoxyl groups of methyl esters and 2.3 ppm from �-carbon ch2 groups of all fatty acid derivatives was used to calculate the percentage yield of methyl ester. meanwhile, the chemical composition of volatile and its abundance of biodiesel produced was determined using gas chromatography (gc) recorded from hewlett packard gas chromatography model 6890. helium gas was used as the mobile phase and column db-wax with speci�cation 0.25 �m thicknesses, 30 m length and 0.20 mm internal diameter as the stationary phase with flame ionization detector (fid). the dilution of biodiesel to n-hexane was 1:5 ml. the injector temperature rate was set at 40°c/5 min and the detector temperature was �xed at 300 °c for 15 minutes. the temperature was programmed at 5°c/min and the �ow rate was 10 ml/min. for this product analysis, approximately 1 �l of this mixture was injected into the gc. © 2020 the authors. page 63 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 3. results and discussion 3.1 catalysts characterizations 3.1.1 thermogravimetric analysis–di�erential thermal analysis (tga-dta) in the preparation of cao samples, thermogram tga-dta for the optimum activation temperature was identi�ed in the decomposition of caco3. figure 1 illustrates the percentage weight loss for the decomposition of caco3 at di�erent temperature regions. based on figure 1, there are four major weight loss that occurred from the decomposition of caco3 to cao at 60 to 700 °c. the �rst region occurred at temperature range of 60 to 100 °c was 1.6%. this occurrence was related to the removal of physically adsorbed water at caco3 surface. the second region showed that the percentage weight loss occurred at 100 to 250 °c was 1.3% due to the loss of hydroxyl groups on the surface that attached to ca2+. besides, the third region indicated the weight loss that occur at 250 to 600 °c was 1.4% due to the loss of carbonate group from caco3. the major weight loss occurred at 600 to 700 °c about 3.4% was related to the decomposition of calcium carbonate, caco3 to calcium oxide, cao as in good agreement with kristl et al. (2019). this weight loss implied the beginning formation of surface modi�ed cao from removal of carbon dioxide, co2 as the by-product. as shown in figure 1, it could be inferred that decomposition of caco3 to cao occurred at temperature higher than 600 °c. therefore, as the sample weight remained constant after 700 °c, this temperature was considered suitable for complete decomposition of caco3 into cao. figure 1. tga-dta pro�le of caco3 sample 3.1.2 fourier transform infrared (ftir) analysis figure 4 illustrates the ftir spectra for all prepared cao samples calcined at temperatures of 100 to 800 °c. the peak at 3640 cm−1 demonstrates that o-h bond stretching vibration at surface water attached to ca2+. as the temperature was increased from 100 to 800 °c, the band at 3640 cm−1 becomes smaller and disappeared. this indicated that the prepared cao-700 did not contain water. this is in accordance with tga-dta data where the percentage weight loss occurred at temperature of 100 to 250 °c was most probably related with the loss of hydroxyl group at surface that attached to ca2+. the minor bands at 2920 cm−1 and 2870 cm−1 were corresponded to the c=o bond stretching vibration from carbonate ion. the thin and intense band at 1796 cm−1 was also associated to the carbonate c=o bond. as increasing the temperature from 100 to 800 °c, the peak became smaller and disappeared due to the loss of c=o bond from the formation of cao. besides, the very strong bands at 1400 cm−1, 870 cm−1 and 848 cm−1 were related to the three di�erent elongation modes of c-o bond bending vibration. the peak at 2513 cm−1 shows the harmonic vibration of these elongation modes for c-o bond bending vibration. figure 2. ftir spectra of prepared cao samples at various calcination temperatures of (a) cao-100 at 100 ºc, b) cao-200 at 200 ºc, (c) cao-300 at 300 ºc, (d) cao-400 at 400 ºc, (e) cao-500 at 500 ºc, (f ) cao-600 at 600 ºc, (g) cao-700 at 700 ºc, and (h) cao-800 at 800 ºc 3.1.3 x-ray di�raction (xrd) analysis figure 3 shows the xrd di�ractograms for all prepared cao samples at di�erent calcination temperatures from 100 to 700°c, while table 1 represents xrd peaks assignment for cao-600 and cao-700. in this study, the temperature for decomposition of caco3 to cao was determined by referring to the tga-dta and ftir data which shows the optimum temperature of forming cao started at 600°c and above. based on figure 2, as the temperature increased, the hexagonal of ca(oh)2 peaks became smaller and the cubic cao crystal started to appear. finally, at 700°c, all the rhombohedral caco3 and hexagonal ca(oh)2 totally disappeared and only cubic cao was detected. this was probably due to the sintering e�ect which changes the sample characteristic and hydroxides group have been eliminated from the sample, thus completely converted to cao (li et al., 2020). furthermore, the crystallite size for the prepared cao nanoparticles was calculated using sherrer’s equation. the prepared surface modi�ed cao was truly at nano size as in accordance with (duan et al., 2007). from the calculation, it was found that cao-700 was completely in cubic crystal structure with crystallite size of 38 nm. 3.1.4 nitrogen adsorption analysis (na) the speci�c bet surface area, sbet of cao samples at di�erent calcination temperatures are listed in table 2. the sbet shows an increasing pattern of cao samples as the temperature increased from 100 to 700 ºc. the highest sbet obtained was cao-700 with 11.5 m2g−1. the increased surface area could be © 2020 the authors. page 64 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 table 1. xrd peaks assignment for cao-600 and cao-700 sample angle, d (å) d (å) miller peaks 2� reference index, hkl assignment hkl cao-600 29.46 3.03 3.02 104 rhombohedral 32.23 2.77 2.78 111 cubic 37.36 2.41 2.41 200 cubic 53.88 1.7 1.7 220 cubic 64.21 1.45 1.45 311 cubic 67.47 1.39 1.39 222 cubic 79.78 1.2 1.2 400 cubic cao-700 32.26 2.77 2.78 111 cubic 37.41 2.4 2.41 200 cubic 53.86 1.7 1.7 220 cubic 64.11 1.45 1.45 311 cubic 67.39 1.39 1.39 222 cubic 79.71 1.2 1.2 400 cubic figure 3. xrd di�ractograms of prepared cao samples at various calcination temperatures of (a) cao-100 at 100 ºc, b) cao-200 at 200 ºc, (c) cao-300 at 300 ºc, (d) cao-400 at 400 ºc, (e) cao-500 at 500 ºc, (f ) cao-600 at 600 ºc, (g) cao-700 at 700 ºc, and (h) cao-800 at 800 ºc explained by the decomposition of caco3 to cao and co2 at higher calcination temperature. this treatment subsequently created defect sites as a cavity of prepared cao to give the increment of its catalyst surface area. as the temperature reached at 800 °c, the sbet slightly decreased due to the sintering e�ect and particle agglomeration at high temperature. similar �nding was reported previously (hipólito and martínez, 2020). 3.1.5 field emission scanning electron microscopyenergy dispersive x-ray (fesem-edx) the structural changes in cm-caco3 during modi�cation was studied by using fesem micrographs as illustrated in figure 4 (a). the results demonstrated that cm-caco3 was a mixture of bulky particles which had oval shape agglomerates with each other. the morphology of cao-700 is illustrated in figure 4(b). the table 2. the speci�c bet surface area, sbet of the prepared cao calcined at various temperatures sample speci�c bet surface area, sbet (m2g−1) cao-100 7.9 cao-200 9 cao-300 10.4 cao-400 10.6 cao-500 10.7 cao-600 11 cao-700 11.5 cao-800 10.6 properties of the resulting modi�ed cao samples were a�ected by the calcination temperature of caco3. it was found that the large pores were present between cao particles that bond with each other. a fesem image for cao-700 showed the spherical particles coagulated to form agglomerates. besides, figure 5 (a) and (b) show the elemental composition by edx analysis in cm-caco3 and cao-700, respectively. it was found that cmcaco3 contained 19.88% weight percentage of carbon, 46.29% of oxygen and 33.83% of calcium, while cao-700 contained 53.56% of oxygen and 46.44% of calcium. 3.1.6 basicity of calcium oxide nanoparticles the basicity of the catalyst is most signi�cant because this site would a�ect the chemical reactions. thus, back titration method was performed to determine the basicity of the cao nanoparticles. the basicity of the prepared cao was correlated with temperature for decomposition of cm-caco3. in the back-titration method, distilled water was added to cao and left for 24 hours © 2020 the authors. page 65 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 figure 4. fesem images of (a) cm-caco3 (25kx); (b) cao-700 (25kx) figure 5. edx elemental analysis for (a) cm-caco3; (b) cao-700 to make the reaction to occur. then, the h+ from water was adsorbed by lone pair of oxygen from cao surface which corresponds to the amount of basic site (eq. 1). the desired species, oh− was obtained by �ltering the slurry of extracted proton in cao. next, in the neutralization step, the oh− in clear solution reacted with the hcl to produce water and chloride ion, cl− (eq. 2). while in back titration step, the chloride ion, cl− was further reacted with sodium hydroxide, naoh and phenolphthalein indicator was used to detect the presence of oh− at the end of the reaction by giving pink color solution (eq. 3). figure 6 shows the basicity of the prepared cao samples at di�erent calcination temperatures. ca-o + h+⋯⋯oh− ⟶ ca-o⋯⋯ h+ + oh− (1) oh− + hcl ⟶ h2o + cl− (2) cl− + naoh ⟶ nacl + oh− (3) figure 6 shows that higher calcinations temperature gave the higher basicity which achieved maximum value at 700 °c. at lower temperature, the cao nanoparticles surface was mostly covered with the oh centres, thus decreased the basicity. by increasing the temperature, more o2− centres started to develop, hence gave a higher basicity. this data is in good agreement with ftir study that indicated the o-h bonds started to diminish at higher temperature of activation. in a previous study by yacob et al. (2010), this �nding was also in accordance to that used mgo catalyst. it was proven that the basic sites of mgo was detected if the calcinations temperature was above 600 °c which was no free oh− groups detected by ftir. furthermore, basicity of cao slightly decreased as the temperature reached 800 °c. the fracture of cao molecular framework and the breaking of crystal structure can describe these results. moreover, this graph proved that the highest basicity was obtained by cao-700 sample which about 1.959 mmol/g. based on the higher amount of basicity, the prepared cao-700 was selected as heterogeneous base catalyst for the transesteri�cation of rice bran oil to biodiesel. figure 6. basicity of the prepared cao samples at di�erent calcination temperatures 3.2 biodiesel analysis 3.2.1 nuclear magnetic resonance (nmr) nmr is an important analytical technique that is used to determine the quantitative production of biodiesel and the fatty acids mainly the common unsaturated fatty acids such as oleic and linoleic acids (mantovani et al., 2020). from the previous studies, 1h nmr spectra had been interpreted for soybean oil which were 0.8 ppm related to terminal methyl hydrogen, a strong signal at 1.3 ppm indicates the methylenes of carbon chain, a multiplet signal at 1.6 ppm indicates the �-carbonyl methylenes, a triplet signal at 2.3 ppm related to �-carbonyl methylenes, 3.6 ppm from methoxy group and signal associated to unsaturation at 2.0 ppm, 2.8 ppm and 5.3 ppm indicates to allylic, bis-allylic and ole�nic hydrogen respectively (atabani et al., 2019). the higher conversion of biodiesel was identi�ed if no signal appeared between 4.0 ppm to 5.2 ppm because h-1 and h-3 peaks (refer figure 7) were corresponded to proton attached at glycerol carbons. figure 7 shows the transesteri�cation process for biodiesel. figure 7. transesteri�cation process for biodiesel figure 8 illustrates 1h nmr spectra of rice bran oil sample, while figure 9 and table 3 demonstrate the 1h nmr spectra and peaks assignment for the prepared biodiesel with di�erent times of reaction, respectively. as shown in figure 8, there was no peak observed at 3.6 ppm that is an important indicator for presence of biodiesel samples. after the transesteri�cation reaction occurred, the peak at 3.6 ppm was determined due to the methoxyl group. the h-1 peak was observed at 4.096 ppm to 4.141 ppm and the h-3 peak was determined at 4.262 ppm to 4.302 ppm from the spectrum shown in figure 9. in addition, figure 9 illustrates that peak at 3.6 ppm appeared in all samples of biodiesel due to the © 2020 the authors. page 66 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 methoxyl group (-o-ch3) present in the samples. the small h-1 and h-3 peaks at 4.0 ppm to 5.2 ppm which corresponded to protons attached at glycerol carbons can be seen at the reaction of 30 minutes until 150 minutes. then, when the times of reaction increased, this peak was slightly disappeared due to the higher conversion for biodiesel production. as explained by yoo et al. (2010), as transesteri�cation reaction proceeded, h-1, h-2 and h-3 would shift toward higher �eld as a result of the loss of high electron density of the acyl group, while the proton of acyl group could not shift when one or two of acyl groups migrated from triglycerides (tgs), yielding sn-diglycerides (sn-dgs) or sn-monoglycerides (sn-mgs). the proton of acyl groups resonates at 0.8-2.9 ppm in tgs (yoo et al., 2010). besides, the ratio between the peak of 3.6 ppm from methoxyl groups of methyl esters and 2.3 ppm from �-carbon ch2 groups of all fatty acid derivatives was calculated for the percentage yield of methyl ester (shirley and alesandro, 2008). from the calculation, cao-700 produced 89.0% methyl esters or biodiesel from rice bran oil. thus, nmr analysis proved that biodiesel was successfully prepared from single step transesteri�cation of rice bran oil using the prepared cao-700 catalyst. figure 8. 1h nmr spectrum of rice bran oil sample table 3. 1h nmr peaks assignment for biodiesel at di�erent reaction times sample 1h nmr regions (ppm) peaks assignment biodiesel 0.850 – 0.900 -(ch2)n-ch3 1.230 – 1.290 -(ch2)n1.580 – 1.630 ch3o2-c-ch2-ch21.960 – 2.060 -ch2-ch2-ch=ch2 2.270 – 2.300 ch3o2-c-ch22.740 – 2.790 -ch=ch-ch2-ch=ch3.658 -o-ch3 4.100 – 4.160 -h2cooc(ch2)n-ch3 4.250 – 4.320 -h2cooc(ch2)n-ch3 5.240 – 5.380 -ch=chfigure 9. 1h nmr spectra of the prepared biodiesel at di�erent reaction times 3.2.2 gas chromatography – flame ionization detector (gc-fid) figure 10 illustrates the gc-fid chromatogram of the prepared biodiesel at 60 minutes, while table 4 shows peaks assignment for retention times from gc-fid chromatogram for the prepared biodiesel. it was found that there were peaks due to the appearances of methyl laurate, methyl tetradecanoate, methyl palmitate, methyl palmitoleate, methyl stearate, methyl oleate, methyl linoleate and methyl tetracosanoate. based on table 4, it was found that the most methyl esters that present in the produced biodiesel were methyl tetradecanoate, methyl palmitate and methyl oleate. thus, gc-fid analysis proved that the biodiesel was successfully prepared by single step transesteri�cation of rice bran oil with methanol and the prepared cao-700 catalyst. figure 10. gc-fid chromatogram of prepared biodiesel at 60 minutes © 2020 the authors. page 67 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 table 4. peak assignment for type of fatty acid methyl ester towards retention times from gc-fid chromatogram type of fatty acid retention times, methyl ester min methyl laurate 14.9 methyl tetradecanoate 17.5 methyl palmitate 19.8 methyl palmitoleate 19.9 methyl stearate 21.7 methyl oleate 22 methyl linoleate 23.4 methyl tetracosanoate 27.5 3.3 catalytic activity 3.3.1 e�ect of catalyst loading the e�ect of catalyst loading towards production of biodiesel using di�erent loadings of catalyst which were 0.5% to 2.5% with 60 minutes reaction times as illustrated in figure 11. from figure 11, it shows that 1.0% catalyst loading gave the highest percentage of conversion for biodiesel yield with 89.0%. for 0.5% catalyst loading, the percentage biodiesel production only gave 60.3%, indicating small surface area of the sample. moreover, incomplete production of fame was due to an insu�cient amount of catalyst as reported by (olutoye et al., 2016). as increasing the catalyst loading to 1.5% in the reaction, the percentage of biodiesel yield decreased due to its deactivation. the resistance produced by mixing reactant, product and solid catalyst could be the main reason of these results. such �nding was in good agreement with sulaiman et al. (2020) where it can inhibit the production of biodiesel. figure 11. the percentage conversion for biodiesel with di�erent percentage catalyst loadings over cao-700 3.3.2 e�ect of reaction times figure 12 shows the e�ect of reaction times towards the production of biodiesel. interestingly, it was found that the conversion for biodiesel was increased with increasing the reaction times from 30 to 210 minutes and gave 100% conversion of rice bran oil at 210 minutes. this result showed that the low production of biodiesel was found in 30 minutes. sulaiman et al. (2020) have reported that it is due to the presence of the heterogeneous catalytic mass transfer system. when the reaction time increased to 60 minutes, it can provide more contact times between reactants and catalysts to give high frequent collision. therefore, high fame content in the transesteri�cation process can be achieved using an appropriate reaction time while forming adequate quantities of these triglyceride derivatives. figure 12. the percentage conversion for biodiesel with di�erent reaction times over cao-700 4. conclusions the cao nanoparticles was successfully prepared from commercial calcium carbonate, cm-caco3 by thermal decomposition method. the tga-dta data showed that there was no more weight loss occurs after 700°c and it veri�ed that caco3 was completely decomposed into cao. the ftir results supported the tga-dta data which indicated the formation of cao from the decomposition of caco3 occurred at 500 to 600°c and completely become cao at 700°c. besides, the xrd results con�rmed that all the rhombohedral caco3 and hexagonal ca(oh)2 were totally disappeared and only cubic cao existed at 700°c. the crystallite size of prepared cao-700 nanoparticles was 38 nm that calculated from sherrer’s equation. it veri�ed that cao-700 was completely in cubic nanocrystal structure. for nitrogen adsorption analysis, cao-700 gave the highest bet surface area (11.5 m2g−1), where catalytic reactions could e�ectively work at the surface-active sites. in addition, cao-700 gave the highest basicity with 1.959 mmol/g in order to achieve maximum biodiesel production. in the biodiesel analysis, nmr data con�rmed the presence of methoxyl group (-o-ch3). the percentage biodiesel production that calculated from the ratio between the peak of 3.6 ppm from methoxyl groups of methyl esters and 2.3 ppm from �-carbon ch2 groups of all fatty acid derivatives found that cao-700 produced 89.0% of biodiesel at 60 minutes. gc-fid analysis veri�ed that the biodiesel was successfully prepared by single step transesteri�cation of rice bran oil with methanol and prepared cao-700 as a catalyst with the presence of methyl laurate, methyl tetradecanoate, methyl palmitate, methyl palmitoleate, methyl stearate, methyl oleate, methyl linoleate and methyl tetracosanoate. © 2020 the authors. page 68 of 69 sulaiman et. al. science and technology indonesia, 5 (2020) 62-69 5. acknowledgement the authors would like to thank the ministry of higher education (mohe), malaysia and universiti teknologi malaysia (utm) for their �nancial funding through utm transdisciplinary research grant (cost center no. 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8686–8689 © 2020 the authors. page 69 of 69 introduction experimental section materials catalysts preparation catalysts characterizations catalytic transesterification reaction product analysis results and discussion catalysts characterizations thermogravimetric analysis–differential thermal analysis (tga-dta) fourier transform infrared (ftir) analysis x-ray diffraction (xrd) analysis nitrogen adsorption analysis (na) field emission scanning electron microscopyenergy dispersive x-ray (fesem-edx) basicity of calcium oxide nanoparticles biodiesel analysis nuclear magnetic resonance (nmr) gas chromatography – flame ionization detector (gc-fid) catalytic activity effect of catalyst loading effect of reaction times conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 2, april 2019 research paper synthesis and characterization of zn/al, zn/fe, and zn/cr layered double hydroxides: e�ect of m3+ ions toward layer formation neza rahayu palapa1, yosi saria1, tarmizi taher2, risfidian mohadi3, aldes lesbani3* 1magister of chemistry, faculty of mathematics and natural sciences, sriwijaya university, jl.. padang selasa bukit besar palembang 30139 2department of enviromental science, graduate school, sriwijaya university, jl. padang selasa no. 524 ilir barat 1, palembang-south sumatra, indonesia 3department of chemistry, faculty of mathematics and natural sciences, sriwijaya university, jl. palembang-prabumulih, km. 32, ogan ilir, south sumatra, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstract layered double hydroxides are composed by substitution of metal cation divalent and trivalent. metal cation divalent and trivalent can be changed. in this work, e�ect metal cation trivalent (m3+) toward layer formation were studied. synthesis of ldhs has used co-precipitation methods with molar ratio 3:1 and kept ph at 10. the result of synthesis was characterized by x-ray di�raction (xrd) and fourier transform infrared (ft-ir) analyses. keywords layered double hydroxides, ldhs, co-precipitation, zn/al ldhs, zn/cr ldhs, zn/fe ldhs received: 3 maret 2019, accepted: 19 april 2019 https://doi.org/10.26554/sti.2019.4.2.36-39 1. introduction inorganic materials can be classi�ed by layered materials (ma et al., 2009) and porous materials (abdelrahman, 2018). each of these materials has advantages as adsorbents (taher et al., 2018; palapa et al., 2018c), catalyst (jadhav et al., 2007), ion exchangers (lins et al., 2018) and sensors (xu et al., 2018b). one of the most interesting material is layered materials (mishra et al., 2018). based on its existence, nature layered materials such as kaolinite and bentonite (taher et al., 2018, 2017) then synthesized layered material such as layered double hydroxides or hydrotalcite (jadhav et al., 2007; lesbani et al., 2018; palapa et al., 2018b). nowadays, researchers had been interesting to layered materials especially layered double hydroxides. layered double hydroxides are more e�ective to be modi�ed because layered double hydroxides have a �exible structure (takei et al., 2014) and easy to handle (li et al., 2017). ldhs has many physical and chemical properties which are similar to cationic clay minerals (zhao et al., 2011). their layered structure, extensive chemical composition (due to isomorphic variable metal cation substitution), ion exchange properties chen (2011), reactive interlayer space (xu et al., 2018a), swelling in water, rheological properties and colloids have made ldh like mineral clay (zhao et al., 2011). generally, layered double hydroxides have a general formula of m2+ m3+ (oh)2(an-)x/n.yh2o where m3+ and m2+ are represented the trivalent metal and divalent metal, respectively (tichit et al., 2019; lins et al., 2018). formed as 1 − xx layered double figure 1. structure of layered double hydroxides was had nitrate anion hydroxides (ldhs) and prepared by two metal salts (divalent and trivalent metal) (islam and patel, 2010; palapa et al., 2018a). in this case, the trivalent metal that essentially can be al, fe, ni, cr, ga, and mn (elmoubarki et al., 2017). while, the divalent metals cation such as mg, mn, co, cu, zn, and fe. an interlayer anion as counterbalancing the metals cations (lesbani et al., 2018). the anion can be taken up by layered double hydroxides uses three mechanisms such as anion exchanges in interlayer, surface adsorption and reconstruction layered double hydroxides calcined by ‘memory e�ect’ (gaini et al., 2009). in this research, the e�ect of the comparison of ion m3+ metal cation trivalent from zn/al, zn/fe, and zn/cr layered double hydroxides. the ldhs has been successfully prepared and characterized by xrd and ft-ir analyses. https://doi.org/10.26554/sti.2019.4.2.36-39 palapa et. al. science and technology indonesia, 4 (2019) 36-39 2. experimental section 2.1 chemicals and instrumentation all chemicals material was used analytical reagents grade such as zinc nitrate, aluminum nitrate, chromium nitrate, iron nitrate were obtained by merck. sodium hydroxide and sodium carbonate were obtained by from sigma-aldrich. the solution was prepared by deionized purity water. then characterized by xrd di�ractometer rigaku mini�ex-600 and spectrophotometer ft-ir shimadzu ft-ir prestige-21. 2.2 synthesis of zn/m3+ (m3+: al, fe, and cr) ldhs zn/al, zn/fe, and zn/cr ldhs material have been prepared by co-precipitation method at constant ph. the synthesized of ldhs were used the molar ratio 3:1 was conducted zinc nitrate (100 ml, 0,3 m) and a trivalent metal cation such as aluminum nitrate, iron nitrate, chromium nitrate (100 ml, 0.1 m), respectively. this solution was called a solution. then a solution was stirring for an hour. b solution was prepared by 10 ml of sodium solution 2.5 m and 10 ml of naoh 3 m. then b solution was added slowly to a solution under vigorous stirring of 2 hours and adjust ph at 10 by addition of naoh and temperature kept at 60 °c for 24 hours to obtain layered double hydroxides. after that, layered double hydroxides were washed and kept at room temperature. 3. results and discussion synthesis of zn/al, zn/cr, and zn/fe layered double hydroxides were obtained from metal cation divalent e.g. zinc nitrate and metal cations trivalent such as aluminum nitrate, iron nitrate, and chromium nitrate. layered double hydroxides have successfully prepared by co-precipitation method with molar ratio and adjust ph at 10 by adding naoh. co-precipitation method is based on the complex condensation to build the brucite layers with exchanges of metal cation divalent and trivalent and balancing by anion in the interlayer. the result of zn/al, zn/fe, and zn/cr ldhs was shown in fig. 2. the result has remained white powder, brown powder and grey powder, respectively. then, zn/al, zn/fe, and zn/cr ldhs were characterized by xrd di�ractogram. according to forano et al. (2006) layered double hydroxides (ldhs) has an octahedral-hydroxyl layer which has a positive charge because of substitution of metal cation divalent and metal cation trivalent (lesbani et al., 2018). this brucite layer described the close packing structure of metal cation and hydroxyl anion. brucite layers balanced by anion and water molecules namely interlayer. x-ray di�raction is one of the most e�ective methods to determine the synthesis process. the result of x-ray di�raction shows in fig. 3. the pattern of zn/al, zn/fe, and zn/cr ldhs was shown in fig 3. fig. 3 shows a similar characteristic of layered double hydroxides has sharp peaks at 2� amount 10°, 22°, 30°, 35°, 49° and overlapping peaks at 60° are responding to (003), (006), (012), (104), (018) and (110) re�ections, respectively. the sharp peak amount 10o for all compounds was indicated interlayer of layered figure 2. powder of zn/al ldhs (a), zn/fe ldhs (b) and zn/cr ldhs (c) double hydroxides. the higher value of interlayer is zn/cr (7.68 å) > zn/al (7.57 å) > zn/fe (5.80 å). in this case, the e�ect of ionic radii a�ects the distance between layers (interlayer) due to the di�erence in ionic radii where metal cation trivalent cr3+ (0.64 å), al3+ (0.53 å) and fe3+ (0.61 å). according to forano et al (2006) the in�uence of the biggest metal ionic radii will be transformed interlayer higher than interlayer of smaller metal ionic radii [24]. however, in this study, the assumption was not answered because zn/fe ldhs had the smallest interlayer due to the synthesis of zn/fe ldh experiencing impurities and calcite formed due to the temperature that is not kept constant in the synthesis process. according to parida and mohapatra (2012), (003), (006) and (110) re�ections are most important characteristic based on a crystallographic parameter. the crystallographic parameter is the �rst re�ection di�raction pattern for layered double hydroxides. based on braag’s law, layered double hydroxides have a hexagonal structure, to determining hexagonal structure used unit-cell parameters. however, the hexagonal structure has a rule which a=b≠c parameters, its equation: 1/d2(ℎkl) = ((ℎ2 + k2)/a2) + l2/c2 (1) data digital of xrd was showed the value of d-spacing (003), (006) and (110) re�ection. (003) and (006) re�ection was used to calculate the ‘c’ parameter. ‘c’ parameter is a parameter that shows the size of the crystal structure using equation c = 3/2 [(d (003)) + (2d (006))] (benito et al., 2010). di�raction (110) re�ection were used to calculated ‘a’ parameter using equation a = 2d (110). the data of crystallographic parameter were shown in table 1. table 1. crystallography parameters of ldhs parameters zn/cr zn/al zn/fe (003) (å) 7.68 7.57 5.8 (006) (å) 3.81 3.79 3.41 (110) (å) 1.53 1.53 1.49 ’a’ parameter (å) 3.06 3.06 2.99 ’c’ parameter (å) 22.962 22.725 18.933 table 1. were showed the unit cell of parameter crystallographic such a and c parameter. the value of ‘a’ parameters © 2019 the authors. page 37 of 39 palapa et. al. science and technology indonesia, 4 (2019) 36-39 figure 3. xrd di�ractograms of ldhs was obtained similar because of the presence of nitrate anion in interlayer for all ldhs. ‘c’ parameter has denoted that size and crystal structure. the value of ‘c’ parameter of zn/cr ldhs higher than others its means the basal spacing of zn/cr ldhs biggest. zn/al, zn/cr, and zn/fe ldhs have been characterized by ft-ir spectrophotometer analyses. the purpose of characterized by ft-ir is to determine the functional groups from layered double hydroxides (ldhs). the spectra of zn/al, zn/cr, and zn/fe ldhs was shown in fig. 4. all compounds had identical spectra where a broadband vibration from -oh stretching amount wavenumber 3400-3600 cm−1 while the weak vibration from water molecules in interlayer at wavenumber 1635 cm−1. then, the sharp vibration at wavenumber 1380 cm−1 denotes the anion of nitrate as balancing in the interlayer. the m-o bonding vibration was identi�ed at wavenumber under 1000 cm−1. 4. conclusions in this research has been successfully prepared zn/al, zn/cr and zn/fe layered double hydroxides (ldhs) by co-precipitation method with ratio molar 3:1 and kept ph at 10. the result has been characterized by x-ray di�ractograms and ft-ir spectrophotometer analyses. xrd data obtained the value of interlayer zn/cr ldhs (7.68 å) highest than zn/al ldhs (7.57 å) and zn/fe (5.80 å). so, this study can be presented a synthesis of layered double hydroxides and its characterization. figure 4. ft-ir spectrum of ldhs 5. acknowledgement author thankful to hibah tesis magister form ministry of research technology and higher education contract number 0064.01/un9/sb3.lp2m.pt/2019 references abdelrahman, e. a. (2018). synthesis of zeolite nanostructures from waste aluminum cans for e�cient removal of malachite green dye from aqueous media. journal of molecular liquids, 253; 72–82 benito, p., m. herrero, f. labajos, and v. rives (2010). e�ect of post-synthesis microwave–hydrothermal treatment on the properties of layered double hydroxides and related materials. applied clay science, 48(1-2); 218–227 chen, j. (2011). host–guest functional materials. in modern inorganic synthetic chemistry. elsevier, pages 405–428 elmoubarki, r., f. z. mahjoubi, a. elhalil, h. tounsadi, m. abdennouri, m. sadiq, s. qourzal, a. zouhri, and n. barka (2017). ni/fe and mg/fe layered double hydroxides and their calcined derivatives: preparation, characterization and application on textile dyes removal. journal of materials research and technology, 6(3); 271–283 forano, c., t. hibino, f. leroux, and c. taviot-gueho (2006). chapter 13.1 layered double hydroxides. in developments in clay science. elsevier, pages 1021–1095 gaini, l. e., m. lakraimi, e. sebbar, a. meghea, and m. bakasse © 2019 the authors. page 38 of 39 palapa et. al. science and technology indonesia, 4 (2019) 36-39 (2009). removal of indigo carmine dye from water to mg–al–co3-calcined layered double hydroxides. journal of hazardous materials, 161(2-3); 627–632 islam, m. and r. patel (2010). synthesis and physicochemical characterization of zn/al chloride layered double hydroxide and evaluation of its nitrate removal e�ciency. desalination, 256(1-3); 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86–91 xu, y., z. li, k. su, t. fan, and l. cao (2018b). mussel-inspired modi�cation of pps membrane to separate and remove the dyes from the wastewater. chemical engineering journal, 341; 371–382 zhao, d., g. sheng, j. hu, c. chen, and x. wang (2011). the adsorption of pb ii on mg2al layered double hydroxide. chemical engineering journal, 171(1); 167–174 © 2019 the authors. page 39 of 39 introduction experimental section chemicals and instrumentation synthesis of zn/m3+ (m3+: al, fe, and cr) ldhs results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 2, april 2020 research paper malachite green removal by zn/al-citrate ldhs in aqueous solution nurlisa hidayati1*, risfidian mohadi1, elfita1, aldes lesbani1 1chemistry department, faculty of mathematics and natural science, university of sriwijaya, indralaya, south sumatera, indonesia *corresponding author: hidayatinurlisa@yahoo.com abstract zn/al-citrate ldhs was synthesized using co precipitation method at basic condition and the material were applied as adsorbent of malachite green (mg) dye in aqueous medium using batch system. adsorption of mg onto zn/al-citrate was investigated through kinetic, isotherm adsorption and thermodynamic studies. kinetic model was fi�ed pso than pfo for mg adsorption. the rate of adsorption k2 for zn/al ldhs was 0.000692 g.mg−1 min−1 and 0.000371 g for zn/al-citrate ldhs.mg−1 min−1. adsorption of malachite green onto zn/al ldhs and zn/al citrate ldhs was investigated and following langmuir adsorption isotherm model shows chemical adsorption process. the adsorption capacity maximum of zn/al-citrate is 333 mg/g from zn/al ldhs is only 111 mg/g. thermodynamic parameters of zn/al-citrate confirmed adsorption process was endothermic and spontaneous. keywords ldhs, citric acid, intercalation, adsorption, malachite green received: 17 march 2020, accepted: 09 april 2020 https://doi.org/10.26554/sti.2020.5.2.59-61 1. introduction various industries are widely applied dyes to colour their product. disposal of dye wastewater from the dyestu� manufacturing, printing, dyeing and textile industry represent a serious problem all over the world, because in wastewater dyes undergo chemical changes and destroy aquatic life and they even endangers human health (song et al., 2013). cationic reactive dyes are widely used in the tannery, paper, textile industries, distilleries, food beverage etc. malachite green is a cationic base dye used in manufacturing of paints and printing inks. it also most commonly used for dyeing silk, cotton, paper and leather (hameed and el-khaiary, 2008). malachite green has reported to a�ect the immune and reproductive system of animal due to its carcinogenic properties (song et al., 2020). malachite green also represents adverse e�ect on reproductive and immune system (yildirim and bulut, 2020). therefore an increased interest has been focused on removing of such dyes from wastewater. many methods have been used to decolorize dye wastewater including adsorption, membrane �ltration, coagulation, electrochemical methods, oxidation and biological technology. of these techniques due to its e�ective and economical, adsorption is a common method for dye removal (palapa et al., 2019). layered double hydroxide (ldh) is a type of anionic clay having a hydrotalcite crystal structure, that are formed by two kinds of metal ions, usually a divalent and trivalent one, together with hydroxyl group, an interlayer anion and water molecules (pan et al., 2020). the general formula of ldh is [m1−x+2mx+3(oh)2]+3[ax/n].mh2o, where x is the molar ratio m+3/ (m+2 + m+3) ranging from 0.20 to 0.30 in order to avoid the formation of undesirable phase (lesbani et al., 2020). to improve of ldh sorption properties some researchers conducted intercalation in the layer space using anion such as hexacyanoferrat (ii) anion (puzyrnaya et al., 2016) and ethylendiamintetraacetic acid (kameda et al., 2013). the aim of this study was to examine the feasibility of using zn/al-citrate for the removal of mg dyes from aqueous solution. the e�ect of di�erent parameters including contact time, dye concentration and temperature were studied to optimize the sorption process. descriptions of the adsorption process were explored through kinetic parameter, adsorption isotherm and thermodynamic parameter. 2. experimental section 2.1 material and instrumentation all the chemical used in this study were of analytical grade (p.a) zn(no3)2.6h2o, al(no3)2.9h2o, n2 gas, naoh, malachite green and aquadest. the instrument spectrophotometer uv-vis (emc61-pc spektrofotometer) used for measuring concentration of mg. https://doi.org/10.26554/sti.2020.5.2.59-61 hidayati et. al. science and technology indonesia, 5 (2020) 59-61 2.2 methods 2.2.1 synthesis of zn/al-citrate zn/al ldhs was synthesized by coprecipitation method according to palapa et al. (2019). as much as the solution containing zn(no3)2.6h2o 0.3m and al(no3)2.9h2o 0.1m with molar ratio zn/al 3:1 was added one drop at a time to a vigorously stirred solution of naoh and 1 m at a constant solution ph of 10. the resulting precipitate dried hydrothermally at 80oc for 18 h. preparation of zn/al-citrate was conducted under nitrogen atmosphere, 2 gs of zn/al ldh gel was diluted by 50 ml deionized water whereas in another beaker 10 gs of citric acid was diluted by 50 ml deionized water. the solution of ldh added dropwise into citric acid with continoues strirring for 24 hours. wash and dried obtained materials in room temperature. 2.2.2 adsorption experiments mg adsorption were determined using e�ect of contact time, initial concentrationa and temparature adsorption. as much as 0.02 g zn/al ldhs and zn/al-citrate ldhs were contacted with 25 ml of 100 mg/l mg solution for e�ect of adsorption time contact experiments by varying time ranging 5 to 180 minutes. the e�ect of initial concentration and temperature were determined by 140 and 190 mg/l for zn/al ldhs and zn/al-citrate ldhs, respectively, and the various temperature from 30 − 60oc after each adsorption experiment completed, samples were �ltrated to separate supernatant and precipitate. supernatants were analyzed using spectrophotometer at 617 nm. 3. results and discussion 3.1 kinetic models successful application of malachite green removal by ldhs, can be achieved through high adsorption for malachite green in a short time. fig 1 shows malachite green adsorption on ldhs as function of contact time. the rate of malachite green removal by ldhs was sharp at initial time followed by a long slow decline. the adsorption equilibrium was fully established after 120 minutes for both of ldhs. the result show that adsorption of zn/al-citrate ldhs was higher than zn/al ldh. the adsorption rate constant (k) and malachite green adsorbed at equilibrium time were determined from the slope and intercept of linear plot of pseudo �rst order and pseudo second order according to song et al. (2020). table 1 showed mathematical form and parameter of both models. based on table 1, both material were �tted in pseudo second order than pseudo �rst order according to coe�cient correlation was closed to one. this phenomena were supported by adsorption rate of zn/al-citrate for was bigger than pristine. the adsorption capacity of both material indicated that the experimental adsorption capacity in pseudo second order better �tted by calculation adsorption capacity. 3.2 isotherm adsorption the adsorption isotherms were obtained according freundlich and langmuir isotherm. the isotherm model parameters were listed in table 2. table 2 shows the values of the constants figure 1. e�ect of time contact on malachite green adsorption onto zn/al ldhs table 1. kinetics parameter for mg adsorption onto zn/al and zn/al-citrate kinetic model parameters zn/al ldh zn/al-citrate pfo qeexp (mg/g−1) 36.181 119.636 qecalc (mg/g−1) 31.9154 130.617 k1 (min − 1) 0.021 0.03915 r2 0.992 0.935 pso qeexp (mg/g-1) 36.181 119.636 qecalc (mg/g−1) 43.4783 142.657 k2 (g/mgmin) 0.000692 0.000371 r2 0.997 0.998 obtained for the two models. adsorption isoterm data using freundlich and langmuir adsorption isotherm of malachite green on zn/al ldhs showed that langmuir isotherm adjusted best the experimental isotherm with r2 value 0.897-0.9935. it indicated homogeneity of adsorbent and formation monolayer of dye covering the surface of the adsorbent (dos santos et al., 2017). table 2 also showed that the qmax of zn/al-citrate is better at lower temperature which amount of adsorption capacity maximum is 333 mg/g from zn/al ldhs is only 111 mg/g. this phenom indicated the intercalation process of zn/al ldhs was better adsorbed than pristine. however, the favorable of mg adsorption onto zn/al-citrate also denotes by kl which is the value ranging 0<kl<1 (ahmad and kumar, 2010) 3.3 thermodynamic parameters for mg adsorption the thermodynamic parameters which determined in the adsorption of malachite green dye on the synthesized ldhs including enthalpy (δh), entropy (δs) and gibbs free energy (δg). the value of gibbs free energy (δg) is calculated from the enthalpy (δh) and entropy (δs) at various temperature. thermodynamic © 2020 the authors. page 60 of 62 hidayati et. al. science and technology indonesia, 5 (2020) 59-61 table 2. langmuir and freundlich parameters for mg adsorption onto zn/al and znal-citrate ldhs ldh temperature freundlich isotherm langmuir isotherm (k) kf n r2 kl qm (mg/g) r2 zn/al 303 2.559 1.437 0.9182 0.013 111.111 0.9753 313 7.328 2.146 0.9158 0.014 111.111 0.9474 323 13.868 3.058 0.9162 0.025 90.909 0.9843 333 20.137 4.032 0.9206 0.038 83.333 0.9935 zn/al citrate 303 20.417 2.183 0.8395 0.014 333.333 0.897 313 27.606 2.558 0.803 0.023 250 0.9231 323 33.729 2.89 0.8369 0.027 250 0.9579 333 36.475 3.021 0.7731 0.029 250 0.945 adsorption data parameters can be seen in table 3. table 3. thermodynamic parameters for mg adsorption onto zn/al and znal-citrate ldhs t ldh qe δh δs δg (mg.g−1) (kj/mol) (j/mol) (kj/mol) 303 zn/al 34.23 9.653 0.025 1.997 313 37.605 1.744 323 40.506 1.492 333 43.671 1.239 303 zn/al-citrate 118.776 4.904 0.23 -1.95 313 121.308 -2.176 323 123.734 -2.403 333 126.213 -2.629 table 3 showed that the adsorption capacity of malachite green by zn/al ldh and zn/al-citrate increases with increasing temperatures. enthalpy (δh) has a positive value so it can be seen that the reaction is endothermic. gibbs free energy (δg) has a negative for zn/al-citrate denotes that the value mg adsorption process was spontaneity. 4. conclusions kinetics experiment showed adsorption of malachite green on zn/al-citrate ldhs �tted best to pseudo second order showing that process is controlled by chemical adsorption. the adsorption isotherm �tted best to the langmuir model indicate that homogeneity of adsorbent and formation monolayer of dye covering the surface of the adsorbent. thermodynamic parameters for zn/al-citrate con�rmed that endothermic nature of adsorption process, increasing disorder process and spontaneous of adsorption process references ahmad, r. and r. kumar (2010). adsorptive removal of congo red dye from aqueous solution using bael shell carbon. applied surface science, 257(5); 1628–1633 dos santos, r. m. m., r. g. l. gonçalves, v. r. l. constantino, c. v. santilli, p. d. borges, j. tronto, and f. g. pinto (2017). adsorption of acid yellow 42 dye on calcined layered double hydroxide: e�ect of time, concentration, ph and temperature. applied clay science, 140; 132–139 hameed, b. and m. el-khaiary (2008). malachite green adsorption by rattan sawdust: isotherm, kinetic and mechanism modeling. journal of hazardous materials, 159(2-3); 574–579 kameda, t., k. hoshi, and t. yoshioka (2013). preparation of cu–al layered double hydroxide intercalated with ethylenediaminetetraacetate by coprecipitation and its uptake of rare earth ions from aqueous solution. solid state sciences, 17; 28–34 lesbani, a., t. taher, n. r. palapa, r. mohadi, a. rachmat, et al. (2020). preparation and utilization of keggin-type polyoxometalate intercalated ni–fe layered double hydroxides for enhanced adsorptive removal of cationic dye. sn applied sciences, 2(3); 1–4 palapa, n. r., t. taher, r. mohadi, and a. lesbani (2019). removal of anionic direct dye using zn/al, zn/fe and zn/cr layered double hydroxides toward interlayer distance. science and technology indonesia, 4(3); 70–76 pan, x., m. zhang, h. liu, s. ouyang, n. ding, and p. zhang (2020). adsorption behavior and mechanism of acid orange 7 and methylene blue on self-assembled three-dimensional mgal layered double hydroxide: experimental and dft investigation. applied surface science; 146370 puzyrnaya, l., b. yatsyk, g. pshinko, a. kosorukov, and v. y. demchenko (2016). removal of co (ii) and pb (ii) from aqueous solutions by zn/al-layered double hydroxide intercalated with hexacyanoferrate (ii)-ions. journal of water chemistry and technology, 38(4); 200–206 song, j., g. han, y. wang, x. jiang, d. zhao, m. li, z. yang, q. ma, r. e. parales, z. ruan, et al. (2020). pathway and kinetics of malachite green biodegradation by pseudomonas veronii. scienti�c reports, 10(1); 1–11 song, x., r. xu, and k. wang (2013). high capacity adsorption of malachite green in a mesoporous tyre-derived activated carbon. asia-paci�c journal of chemical engineering, 8(1); 172–177 © 2020 the authors. page 61 of 62 hidayati et. al. science and technology indonesia, 5 (2020) 59-61 yildirim, a. and y. bulut (2020). adsorption behaviors of malachite green by using crosslinked chitosan/polyacrylic acid/bentonite composites with di�erent ratios. environmental technology & innovation, 17; 100560 © 2020 the authors. page 62 of 62 introduction experimental section material and instrumentation methods synthesis of zn/al-citrate adsorption experiments results and discussion kinetic models isotherm adsorption thermodynamic parameters for mg adsorption conclusions article http://sciencetechindonesia.com article history received: 8 december 2016 received in revised form: 15 february 2017 accepted: 25 february 2017 doi: 10.26554/sti.2017.2.2.45-49 ©2017 published under the term of the cc by nc sa license science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 45-49 pillarization of double layer hydroxides using h3[α-pw12o40]·nh2o : effect of pillarization time muhammad imron1*, muhammad said1 1department of chemistry, faculty of mathematics and natural sciences, sriwijaya university *corresponding author e-mail : muhammadimron211195@gmail.com abstract the pillarization of mg/al double layer hydroxides using polyoxometalate h 3 [α-pw 12 o 40 ]·nh 2 o by comparing the pillarization time i.e. 3 hours, 6 hours, 9 hours, 12 hours, 24 hours, 36 hours and 48 hours has been done. the product of a pillarization was characterized using an ft-ir spectrophotometer and xrd analysis. the result characterization of ft-ir spectrophotometer does not show the optimum of pillarization each time condition. characterization using xrd shows the optimum pillarization process at 36 hours by showing the existence of double layer hydroxides material at diffraction angle 11.69o deg, 18.30o deg and 34.71o deg. diffraction in the 60o-63o deg indicates the existence of a pillarization double layer hydroxides. keywords: layered double hydroxides, pillarization, polyoxometalate h 3 [α-pw 12 o 40 ]·nh 2 o. introduction inorganic materials can be classified into layered materials and porous materials. these materials have their respective advantages as absorbents, catalysts, ion exchangers, and sensors (lin et al, 1997). the layered material is divided into two types: layered materials are in nature and coated materials are synthesized in the laboratory (han et al, 2017). the layered material in nature has many advantages such as kaolin, halloysite (halloysite), illite, vermiculite, bentonite and much more. the layered compounds that are in the interior have a deficiency that is still a lot of impurities and is difficult to replace (shimizu et al, 2006). meanwhile, the synthetic-coated and modification materials in the laboratory have many advantages i.e. fewer impurities and the structure is easy to replace so it can be modified and widely applied as adsorbent or catalyst for example double layer hydroxides. aside from being an absorbent and a catalyst, double layer hydroxides is usually applied as ion exchangers, catalyst carriers, in industry, and medicine (delidovich & palkovits, 1991). for example, a double-layer hydroxides material commonly used as a catalyst for condensation reactions is mg/al hydrotalcite (mg/al mole ratio in the range of 2.1 to 3.6) with carbonate and nitrate anions in interlayer space (hincapié et al, 2017). in the use of layered materials still have weaknesses that are small surface area and the distance between the narrow layers due to the presence of small exchange ions (goodarzi et al, 2016). to overcome this problem, the double layer hydroxides is modified by means of pillarization. the studies were undertaken by zhang (2004) and qin (2014) double layer hydroxides were inserted anion carboxylic and folic acid compounds and produced a surface area of 40-48 m2/g. this result is better than the undamaged double layer hydroxides surface area of 26 m2/g. when compared kwon and pinnavaia (1989) to zhang (2012), he studied double layer hydroxides was inserted using two types of α[siv 3 w 9 o 40 ]4and h 3 pw 12 o 40 compounds which comprised a keggin-type polyoxometalate compound with 155 m2/g surface area uncoated double layer hydroxides surface area of 26 m2/g. this suggests that the polyoxometalate compound can produce a larger surface area compared to other anion compounds so that the polyoxometalate double layer hydroxides can be effectively used as an adsorbent. based on the pinnavaia (1996), the double layer hydroxides mg/al intercalated with anionic polyoxometalate compound with keggin (α-h 2 w 12 o 40 6-) has a height of 10, while the dawson type (α-p 2 w 18 o 62 6-) has two altitudes of 14.5 and 12.8, finke (co 4 (h 2 0) 2 (pw 9 o 34 ) 2 10-) the double layer hydroxy mg 3 al intercalated with anionic polyoxometalate compound with keggin (α-h 2 w 12 o40 6 -) has a height of 10, while the dawson type (α-p 2 w 18 o 6 26-) has two altitudes of 14.5 and 12.8, finke (co 4 (h 2 o) 2 (pw 9 o 34 ) 2 10-) also has two heights of 13.3 and 12.6. the also has two heights of 13.3 and 12.6. the differences in polyoxometalates orientation are rationalized in terms of different electrostatic interactions and hydrogen bonds between the polyoxometalate pillar and the double layer hydroxide layer. in this study, a double layer hydroxides was pillarized with polyoxometalate h 3 [α-pw 12 o 40 ]·nh 2 o. the pillarization time was studied in order to know the optimal time for these process. experimental section equipments equipments used in this research are a set of standard laboratory, magnetic stirrer, thermometer, hot plate, oven, vacuum, desiccator, x -ray diffraction (rigaku miniflex 600), and ft-ir spectrophotometer (shimadzu prestige-21). materials the materials used in this research are sodium phosphate (na 3 po 4 ), sodium tungstate (na 2 o 4 w), hydrochloric acid (hcl), potassium hydroxide (koh), potassium chloride (kcl), diethyl ether ((c2h5)2o), sodium hydroxide (naoh), sodium carbonate (na 2 co 3 ), magnesium nitrate (mg(no 3 ) 2 ), aluminum nitrate (al(no 3 ) 3 ). mailto:muhammadimron211195@gmail.com imron et al. 2017/science & technology indonesia 2 (2) 2017:45-49 © 2017 published under the term of the cc by nc sa 4.0 licence 46 procedures synthesis of mg/al double layer hydroxides the double layer hydroxy preparation was carried out by mixing as much as 64.01 g of mg(no 3 ) 3 .6h 2 o (2 mol) and 46.64 g of al(no 3 ) 3 .9h 2 o (1 mol) into 150 ml of quads (solution a). a total of naoh with 26.62 g naco 3 was dissolved in 150 ml aquades (solution b). solution a is added to solution b and stirred slowly followed by the addition of 100 ml of aquades and a ph ranging from 9 to 10 to form a precipitate. the obtained precipitate is dried in an oven at 80 °c and ready to be characterized using ft-ir spectroscopy, and xrd analysis. synthesis of polyoxometalate h3[α-pw12o40]·nh2o a total of 125 g of sodium tungstate and 20 g of sodium phosphate were mixed with 187.5 ml of boiling water in 500 ml of a glass beaker. a total of 100 ml of concentrated hydrochloric acid was added slowly to the mixture and stirred using a magnetic stirrer. the stirring process is continuous or continuous which causes the solid to dissolve. the phosphotungstate acid will begin to separate when half of the hydrochloric acid is added then the resulting solution becomes clear and cooled. a cold solution was added 75 ml of diethyl ether and extracted. after extraction process obtained 3 layers which then separated and taken the bottom layer. the bottom layer obtained was evaporated using a rotary evaporator to obtain a white solid h 3 [α-pw 12 o 40 ]·nh 2 o. characterization of h 3 [α-pw 12 o 40 ]·nh 2 o compounds was performed using ft-ir spectrophotometer and xrd analysis. pillarization double-layer hydroxides with polyoxometalate h3[α-pw12o40]•nh2o two grams of double layer hydroxy were dissolved 25 naoh and 1 g of polyoxometalate compound with 50 ml of aquades then heated to 70 oc (using a hot plate) under n 2 gas. after 1 hour of reaction, the temperature is lowered to 30 °c. then the suspension is cooled and the product is washed with water and dried at room temperature. characterization of pillarization compounds was done using xrd, and ft-ir spectrophotometer. results and discussion preparation and characterization of double layer hydroxides, polyoxometalate h3[α-pw12o40]·nh2o and double layer hydroxy pillarization with polyoxometalate h3[α-pw12o40]·nh2o using ft-ir spectrophotometer. synthesis of double layer hydroxides compound using magnesium nitrate and aluminum nitrate to form mg/al double layer hydroxides. m2+ charged metal cations represent magnesium and aluminum represented by m3+ each of which is bound to an oh anion. the results of the process of synthesis this double layer hydroxides are white solid, which is further characterized by using ft-ir spectrophotometer (hanifah & palapa, 2016). the ft-ir spectra of the double layer hydroxides material is presented in figure 1. the widespread vibration peak between the 3800-300 cm-1 wave numbers is the vibration of the oh strain within the structure of the double layer hydroxides. the presence of a peak detected at the wave number 1635.54 cm-1 is the bend vibration of oh. in the region of wavenumber 1381.03 cm-1, there is a vibration which is symmetrical stretching of nitrate and 671.23 cm-1 is nitrate bending vibration. in the wave number 408.91 cm-1 is the vibration of mg-o (swenson et al, 2016). synthesis of polyoxometalate h 3 [α-pw 12 o 40 ]·nh 2 o compound using concentrated hydrochloric acid which aims to form phosphotungstate acid so as to cause the acidity of the polyoxometalate compound to increase. the result of the synthesis of polyoxometalate compound of h 3 [α-pw 12 o 40 ].nh 2 o is in the form of white solid. after the formation of the h 3 [α-pw 12 o 40 ]·nh 2 o, the compound was then characterized using an ft-ir spectrophotometer which serves to identify functional compound groups formed on the h 3 [α-pw 12 o 40 ]·nh 2 o. the ft-ir spectrum of the polyoxometalate h 3 [α-pw 12 o 40 ]·nh 2 o compound of the result of the measurement is shown in figure 2. figure 2 shows the peaks of the functional groups of the polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compound appear at about 4000-400 cm-1 wavenumbers. the wave number 1081 cm-1 is a p-o vibration. the wave number 987 cm-1 denotes the vibration w = o. at the 802 cm-1 wavenumber is a w-oc-w vibration (kim et al.2009). the double layer hydroxides pillilization process with the polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compound was conducted to increase the distance between the double layer hydroxides layer to wider by replacing the oh-anion present in the double layer hydroxides using a larger anion of the polyoxometalate-type keggin [α-pw 12 o 40 ]3-. the double layerhydroxides pillar by using anion [α-pw 12 o 40 ]3 was carried out with aquades augmentation of the polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compound and the addition of sodium hydroxide to the double layer hydroxides material to form a suspension aimed at facilitating the process of anion exchange in the process the pillarization. to find out that there are other anions involved in the process of pillarization such as carbonate, the process of pillarization is done by using inert gas nitrogen. this nitrogen gas can drive and remove carbonate ions and be released as co 2 . therefore, the process of pillarization of double-layer hydroxy material with polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compounds in this study was conducted by varying the time of pillarization figure 1 ft-ir spectra of mg/al double layer hydroxides compound figure 2. ft-ir spectra of the polyoxometalate h 3 [α-pw 12 o 40 ]. nh 2 o imron et al. 2017/science & technology indonesia 2 (2) 2017:45-49 © 2017 published under the term of the cc by nc sa 4.0 licence 47 for 3 hours, 6 hours, 9 hours, 12 hours, 24 hours, 36 hours, and 48 hours for the purpose of determining the double layer hydroxides material which is the most optimized pillarization of the polyoxometalate h 3 [α-pw 12 o 40 ] compound. at the end of the process of pillarization of polyoxometalate compounds h 3 [α-pw 12 o 40 ].nh 2 o obtained white solids. the result of pillarization process of mg-al double-layer hydroxides material with h 3 [α-pw 12 o 40 ].nh 2 o was characterized using ft-ir spectrophotometer to see functional group formed. ft-ir spectrum resulted from the pillaration of double layer hydroxides material with h 3 [α-pw 12 o 40 ].nh 2 o of the measurements shown in figure 3. the presence of functional groups seen in the 3-hours time frame in figure 3a indicates the presence of vibration 3463.15 cm-1 represents o-h stretching. at the 1635.54 cm-1 wavenumber is the vibration of the o-h bond. at the wavenumber 1373.32 cm-1 showing the symmetric nitrate of the synthesis product of the double layer hydroxides mg-al. in the wavenumber 447.49 cm-1 shows the presence of mg-o. these four peaks are also seen in the ft-ir spectra in figure 3b, 3c, 3d, 3e, 3f, and 3g. these four peaks indicate the presence of a mg-al double-layer hydroxides material. figure 3a shows the presence of a vibration peak for a polyoxometalate compound at an 856.39 cm-1 wavenumber indicating a w-oc-w vibration. in figure 3b shows that a vibration peak of a polyoxometalate compound appearing at 1056.99 cm-1 indicates the presence of p-o vibration and 771.53 cm-1 indicating the vibration of w-oc-w. figure 3c shows the presence of w-oc-w vibration at the wave number 786.9 cm-1. figure 3d shows the presence of w-oc-w vibration at the wave number 763.61 cm-1. figure 3e shows the presence of w-oc-w vibration at wavenumber 671.23 cm-1. figure 3f shows the existence of p-o vibration at wavenumber 1049.28 cm-1 and vibration of w-oc-w at wavenumber 779.24 cm-1. figure 3g shows the presence of w-oc-w vibration at the wavenumber 786.96 cm-1. from the results of measurements with ft-ir spectrophotometers, ftir spectrum have not been able to show optimal pillarization results between the comparison of the time of pillarization of 3 hours, 6 hours, 9 hours, 12 hours, 24 hours, 36 hours and 48 hours. next, is measured by x-ray powder diffraction to determine the optimal time of pillarization. characterization of double layer hydroxides, polyoxometalate h3[α-pw12o40]·nh2o and double layer hydroxides pillared with polyoxometalate h3[α-pw12o40]·nh2o using x-ray analysis the double layer hydroxides material characterized using xrd is presented in figure 4. double layer hydroxy has a strong diffraction peak at 2θ value i.e. 11.70 with basal spacing 7.5 . the diffraction angles at 29 deg, 27deg and 28deg are typical of the mg-al double layer hydroxides. according to hurma and kose (2016), the x-ray diffraction pattern showing the layered structure is in the 2θ diffraction of 10deg and 60deg. the layered structure allows the anion to reside on the interlayer of the double layer hydroxides material, according to brandl et al (2017) the peak in the 2θ diffraction pattern of 60o deg indicates that the presence of anions on interlayers may be anion nitrate, carbonate, hydroxy or other anions. analysis of the polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compound was followed by characterization using x-ray diffraction. this characterization is aimed at determining the optimal pillarization time obtained from the crystallinity of the compound and determining the height of the gallery in the layered structure. the xrd pawder pattern of h 3 [α-pw 12 o 40 ].nh 2 o is shown in figure 5. figure 5 shows the x-ray diffraction patterns h 3 [α-pw 12 o 40 ]. nh 2 o compounds with the 2θ main regions of 15-20o deg, 24-31o deg, and 40-45o deg wherein those diffraction are characteristic for crystalline polyoxometalate compounds h 3 [α-pw 12 o 40 ].nh 2 o. the result of the measurement analysis is known that the highest peak occurs in the 25-31o deg and 45o deg. further, the polyoxometalate compound is pillared with a double layer hydroxides material at various times of pillarization which aims to increase the distance between layers in a double layer hydroxy material. the polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o compound obtained from the preparation results is further pillarized by double layer hydroxides material. the pillarized material is further characterized by x-ray power diffraction as in figure 6. figure 6a shows the highest peak of 11.50, 23.110, dan 34.520. figure 3. the ft-ir spectrum of double layer hydroxides was pillarized by polyoxometalate with a various times of pillarization (a) 3 hours, (b) 6 hours, (c) 9 hours, (d) 12 hours, (e) 24 hours, (f) 36 hours, (g) 48 hours. figure 4. x-ray diffraction pattern of double layer hydroxides imron et al. 2017/science & technology indonesia 2 (2) 2017:45-49 © 2017 published under the term of the cc by nc sa 4.0 licence 48 figure 5b shows areas comprising regions of 11.560, 23.230, and 34.600 having relatively high crystallinity (matsunaga et al, 2017). these three diffractions denotes the properties of double layer hydroxide materials having a plated structure with a basal spacing of 7.64å, 3.82 å, and 2.59 å, the area that emerged in 600-630 shows an anion adhesion on the interlayer of double layer hydroxide material. figure 6c shows an angular difference of the diffraction form showing the presence of a mg-al double layer hydroxides material in region 2θ having a peak of 11.470 23.220, and 34.630 indicated the successfully of anions present in a double layer hydroxides material. diffraction at 62.020 with a basal value the largest spacing compared to the 3 hours and 6 hours pillarization times. figure 6d has the same diffraction pattern as figure 6a. figure 6e shows a diffraction angle of 11.120, 22.850, and 34.50. figure 5f shows also the presence of a double layer hydroxides pillared material at 11.6910 diffraction angle with a larger basal spacing compared to a double layer hydroxy material of 0.00644 å. diffraction at 18.300 with a larger basal spacing compared to a double layer hydroxides material 0.06 å. as well as the diffraction angle of 18. 330 has a difference of 0.03 å, and the diffraction angle of 4.710 deg has a difference of 0.00466 å. while in figure 6g has a diffraction angle of 11.980, and 35.110 with basal spacing 7.38 å and 2.55 å. therefore, the most success of pillarization is 36 hour time comparison of the other times. conclusion pillarization of mg/al double layer hydroxides with polyoxometalate h 3 [α-pw 12 o 40 ].nh 2 o at various times showed that pillarization at 36 hours can optimal pillar double layer hydroxides. acknowledgement the author would like to thank prof. aldes lesbani, ph.d for fruitful discussion of this research. references brandl, m., sayed, m.h., riedel, i.h., hocka, r., gütay, l. 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(2012). polyoxometalate intercalated mgal layered double hydroxide and its photocatalytic performance. journal of materials science and engineering, 2, 59-63. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 4, october 2020 research paper set covering model in solving multiple cu�ing stock problem sisca octarina1*, devi gusmalia juita1, ning eliyati1, putra bahtera jaya bangun1 11department of mathematics, faculty of mathematics and natural sciences, universitas sriwijaya, inderalaya 30662, south sumatera, indonesia *corresponding author: sisca_octarina@unsri.ac.id abstract cu�ing stock problem (csp) is the determination of how to cut stocks into items with certain cu�ing rules. a diverse set of stocks is called multiple stocks. this study used the pa�ern generation (pg) algorithm to determine the cu�ing pa�ern of three sizes of stocks, then formulated them into the gilmore and gomory model. the set covering model was generated from the gilmore and gomory model. there are two stages of cu�ing where the first stage is based on the length and the second stage is based on the width. based on the results, selected cu�ing pa�erns in the first stage can be used in the second stage. the combination of pa�erns produced in the gilmore and gomory model showed that the use of stocks is less than the use of stocks in the set covering model. keywords cu�ing stock problem, pa�ern generation, set covering model received: 16 september 2020, accepted: 6 october 2020 https://doi.org/10.26554/sti.2020.5.4.121-130 1. introduction integer linear programming (ilp) is one of the optimization sciences applied in the paper industry. the problem with how to cut paper is known as the cutting stock problem (csp). csp is the determination of how to cut stocks into items with certain cutting rules. stock is the basic material used before formed into an item. item is manufactured according to the size requested by customers. diverse stock sizes are known as multiple stocks. stocks that cut into the item, often result in remaining cuts called trim loss. trim loss in large quantities will increase production costs. a good strategy to overcome this problem is by minimizing trim loss. csp was �rst examined by kantorovich, followed by gilmore and gomory who were also successful in formulating csp. csp now has been developed by many researchers. pattern generation (pg) algorithm was proposed suliman (2001) to determine feasible cutting patterns. the improved algorithm called modi�ed branch and bound algorithm was also created (rodrigo et al., 2012; rodrigo, 2013, 2017). but the search for cutting patterns required a lot of time and a high level of accuracy so it took an application that can help to solve it. the application to form cutting patterns using modi�ed branch and bound algorithm in two-dimensional csp (octarina et al., 2017, 2018, 2019) was improved so that the search for a lot number of paper cutting patterns could be done easily. resulting cutting patterns were formed into a model to obtain the optimal trim loss (bangun et al., 2019, 2020; octarina et al., 2020). gilmore and gomory proposed a model for twodimensional csp by extending the column generation technique (cgt) approach in a one-dimensional csp. cgt was a method that can provide the best solution in completing linear programs, because of the approach to solve large-scale linear program problems. some of the researches about pg and cgt have been done ((brandão et al., 2018; mellouli and dammak, 2008; ma et al., 2018; octarina et al., 2019). gilmore and gomory model also can be developed into different formulations using the set covering model. the set covering model can solve problems involving multiple rows and columns. umetani and yagiura (2007) stated that set covering was one of the combinatorial optimization problems and can solve various di�cult problems. caprara et al. (2000) developed the heuristic method for completing the set covering model. they explained that there was no appropriate algorithm in the literature for the set covering model rather than using a good programming tool. set covering research for various dimensions continues to develop. jin et al. (2015) proposed a heuristic algorithm to �nd the initial solutions of csp by considering defective and non-defective stocks. this algorithm was e�ective for two-dimensional stocks but could not eliminate the same patterns. there have been limited studies concerned on the model of multiple csp. therefore, this research intends to implement the set covering model in the multiple two-dimensional csp. the set covering model was completed by the lingo 13.0 program. https://doi.org/10.26554/sti.2020.5.4.121-130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 2. experimental section 2.1 data the data used in this study consisted of 3 types of stock sizes and four di�erent item sizes. the stock sizes are 1022×1200 mm2,1200×1200 mm2, and 1200×1500 mm2 respectively with the item sizes are 282×208 mm2,280×250 mm2,235×185 mm2, and 164×100 mm2 of 20 pieces each. for detail, it can be seen in table 1. table 1. size of items and demands no size of items (mm2) demands (pieces) 1 282 x 208 20 2 280 x 250 20 3 235 x 185 20 4 164 x 100 20 2.2 methods the steps taken in this study are as follows: a. describe the data needed in forming cutting patterns which include stock size (length and width) and the number of demand for each stock. b. process data using the pg algorithm to determine cutting patterns with minimum trim loss. c. create a tree diagram that has been completed with the pg algorithm. d. form tables of cutting patterns are made by the sequence of branches so that cut loss can be obtained. e. formulate the gilmore and gomory model whereas the objective function shows the minimum amount of stock to meet the demand for each item and the constraints ensure that the strips produced in the �rst stage are those used in the second stage. f. solve the gilmore and gomory model using the lingo 13.0 application. g. formulate the set covering model in the following ways: 1. de�ne the variables. 2. determine the objective function that produces the minimum amount of stock to ful�ll the demand for each item. 3. determine constraints by ensuring that all requests are ful�lled. h. solve set covering model using the lingo 13.0 application. i. analyze the �nal results. 3. results and discussion 3.1 pattern generation pattern generation (pg) is one algorithm to determine cutting patterns. cutting pattern obtained using pg in csp is usually obtained from the size of stocks with standard width wk (k=1,2,. . . ,h) cut into items with width wi and length li(i=1,2,. . . ,n). the csp model is as follow: minimize z = ℎ ∑ k=1 m ∑ j=1 cjkxjk + n ∑ i=1 wisi subject to ℎ ∑ k=1 m ∑ j=1 ajkxjk − si = ii (1) xkj,si, cjk,aijk ≥ 0, for all i, j and k whereas aijk = is the number of the item with the width wi which will be cut according to jtℎ pattern from ktℎ pieces (i = 1, 2, . . . ,n; j = 1, 2, . . . ,m; k = 1, 2, . . . ,ℎ) xjk = is the length of ktℎ pieces which will be cut according to jtℎ pattern cjk = is the trim loss si = is the residual length which will produce item with the width wi m = is the number of cutting patterns the pg algorithm is as follows: 1. sort the length l(i), (i = 1, 2, . . . ,n) with descending order. 2. fill the �rst column (j0 = 1) of the matrix using equation (2). aijk = [ (i ′k − ∑ i−1 z=1 azjkiz) wi ] (2) 3. use equation (3) to �nd the cut loss from the cutting pattern cjk = i ′ k − i−1 ∑ z=1 azjkiz (3) 4. set index level (row index), i to n − 1. 5. check current vertices at the itℎ level, for initial vertex (i, j). if vertices have the value equals to zero (aijk = 0), go to step 7. if not, generate the new column jp = j(p−1)+1 with these elements : a. azik = a(z(i−1)k,(z = 1, . . . , i − 1) element to �ll preceding vertices i, j. b. aijk = ai(j−1)k − 1 element to �ll current vertices i, j. 6. fill remaining vertices from the jtℎ column, like a(i+1)jk,a(i+2)jk, . . . ,anjk using equation (3). 7. find the cut loss from the jtℎ cutting pattern using equation (3). go back to step 4. 8. set ip = ip−1 − 1. if ip > 0 redo step 5. if not, stop. the pg algorithm is used to determine the cutting pattern based on the length of two available stock sizes, namely 1022 mm and 1200 mm. by using the data in table 1, the determination of the pattern based on length is described by the available length, and below is the detailed for the �rst pattern. © 2020 the authors. page 122 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 1. sort the length of stocks in descending order, l′k for k = 1, 2 so l′1=1200 mm and l ′ 2=1022 mm. 2. sort the length of items in descending order, li for i = 1, 2, 3, 4 so l1=282 mm, l2=280 mm, l3=235 mm, and l4=164 mm. 3. fill the element of �rst row (i = 1) , �rst column (j0 = 1) for k = 1 and i = 1, 2, 3, 4, by using equation (2) : ai11 = [ (i ′1 − ∑ i−1 z=1 az11iz) ii ] a111 = [ 1200 − 0 282 ] = 0 a111 = [ 1200 − (4)(282) 280 ] = [ 72 280] = 0 a111 = [ 1200 − (4)(282) − (0)(280) 235 ] = [ 72 235] = 0 a111 = [ 1200 − (4)(282) − (0)(280) − (0)(235) 164 ] = [ 72 164] = 0 4. find the cut loss from the �rst pattern by using equation (3). c11 = i ′ 1 − i−1 ∑ z=1 az11 = 1200−(4)(282)−(0)(280)−(0)(235)−(0)(164) = 72 5. set index level (row index) i0 = n − 1 = 4 − 1 = 3 6. find the new vertex from the third level a311 = 0. 7. subtract 1 from index i0 in step 5, so i1 = 3 − 1 = 2, i1 > 0. 8. the current vertex is in the second level, a211 = 0. 9. subtract 1 from index i1 in step 7, so i2 = 2 − 1 = 1, i2 > 0. 10. the current vertex is in the �rst level a111, a111 > 0, so continue to the next pattern. there are 11 cutting patterns according to the length of 1022 m and 14 cutting patterns according to the length of 1200 mm, which can be seen in table 2 and table 3 respectively. from table 2 for the stock with a length of 1022 mm, it can be seen that by using the �rst pattern, it will yield 3 pieces of items with length 282 mm and an item with a length 164 cm with 12 mm of cut loss, and so on. from table 3 for the stock with the length of 1200 mm, it can be seen that by using the �rst pattern, it will yield 3 pieces of items with length 282 mm and 2 pieces of items 164 mm with 26 mm of cut loss, and so on for the next pattern. according to the width, there are 38 cutting patterns of width 1200 mm and 65 cutting patterns of width 1500 mm, which can be seen in table 4 and table 5. it can be seen from table 4, there are 4 pieces of items of width 250 mm and an item of width 185 mm for the �rst cutting pattern. the trim loss for this �rst pattern is 15 mm. it continues until the 38tℎ cutting pattern. meanwhile, from table 5, we can see that the �rst pattern only yields 6 pieces of items of width 250 mm without cut loss. all the cutting patterns in table 2-5 have a maximum of 60 mm of cut loss. 3.2 the gilmore and gomory model the gilmore and gomory model are as follows. minimize z = j ∑ j�j0 �0j (4) subject to : m ′ �̄ = 0 m ′′ �̄ ≥ b �̄ ≥ 0and integer with m′ and m′′ are m’ in the �rst row and m” in the last row of m. �̄ = [�01...�0j �11...�1j �21...�2j ...�m ′ 1 ...�m ′ j ]t �0j is the jtℎ cutting pattern in the �rst stage. �sj is the jtℎ cutting pattern that related to sth pattern in the second stage, where s�(1, . . . ,m′). b = [b1b2...bm]t is the number of demand of item i. the objective function in this case is to minimize the use of stocks. meanwhile, the problem is how to determine the optimal cutting pattern with minimum stock usage. cutting is done in the �rst stage along the length and then in the second stage along the width. the gilmore and gomory model for the stock of 1022×1200 mm2 can be seen in equation (5) and constraints (6)-(14). minimize z = 11 ∑ j=1 �0j (5) subject to 4 ∑ j=0 �0j + �07 + 3(�06 + �09 + �010 + 2�011) − �11 = 0 (6) �03 + �06 + �09 + 3(�05 + �08) + 2�010 − 4 ∑ j=1 �2j = 0 (7) © 2020 the authors. page 123 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 table 2. cutting patterns according to the length of 1022 mm the the length for each cutting pattern cut loss j-th cutting pattern 282 mm 280 mm 235 mm 164 mm (mm) 1 3 0 0 1 12 2 2 1 0 1 14 3 2 0 1 1 59 4 1 2 0 1 16 5 1 0 3 0 35 6 1 0 1 3 13 7 0 3 0 1 18 8 0 1 3 0 37 9 0 1 1 3 15 10 0 0 2 3 60 11 0 0 0 6 38 table 3. cutting patterns according to the length of 1200 mm the the length for each cutting pattern cut loss j-th cutting pattern 282 mm 280 mm 235 mm 164 mm (mm) 1 3 0 0 2 26 2 2 1 0 2 28 3 2 0 2 1 2 4 1 2 0 2 30 5 1 1 2 1 4 6 1 0 3 1 49 7 1 0 1 4 27 8 0 3 0 2 32 9 0 2 2 1 6 10 0 1 3 1 51 11 0 1 1 4 29 12 0 0 5 0 25 13 0 0 3 3 3 14 0 0 0 7 52 �02 + 2�04 + 3�07 + �08 + �09 − 10 ∑ j=1 �3j = 0 (8) 3�01 + 2(�02 + �03) + �04 + �05 + �06 − 23 ∑ j=1 �3j = 0 (9) 12�11 + 10�12 + 8�22 + 6�23 + 4�24 + 9�31 + 2�32 +7�34 + 5�35 + 3�36 + �37 + 4�38 + 2�39 + 8�41 + 6�42 +4�43 + 2�44 + 4�25 + 4�54 + 2�46 + 2�48 + �410 + 7�411 + 5�412 +5�414 + 3�415 + 3�415 + 3�416 + �417 + �418 + 3�419 + �420 + 2�421 ≥ 20 (10) �21 + 2�22 + 3�23 + 4�24 + 4�23 + 5�33 + �35 + 2�36+ 3�37 + �103 + �412�24 + 3�43 + 4�44 + 2�45 + 3�46+ 4�47 + 2�48 + 3�49 + 4�413 + �415 + �417 + 2�420 + �422 ≥ 20 (11) �31 + �322 + 2�35 + 2�36 + 2�37 + 3�38 + 4�39 + 4�310 + 4�411 + �411 + �413+ �414 + �415 + �416 + �417 + �418 + 2�419 + 2�420 + 3�421 + 3�422 + 3�423 ≥ 20 (12) �41 + �42 + �43 + �44 + 2�45 + 2�46 + 2�47 + 3�48 + 3�49 + 5�410 +�411 + �412�413 + 2�414 + 2�415 + 3�416 + 3�317 + 4�418+ �39 + 4�310 + 4�411 + �419 + �420 + �421 + �422 + �423 ≥ 20 (13) � ≥ 0 (14) © 2020 the authors. page 124 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 table 4. cutting patterns according to the width of 1200 mm the the width for each cut the the width for each cut j-th cutting cutting pattern (mm) loss j-th cutting cutting pattern (mm) loss pattern 250 208 185 100 (mm) pattern 250 208 185 100 (mm) 1 4 0 1 0 15 20 1 1 0 7 42 2 4 0 0 2 0 21 1 0 5 0 25 3 3 2 0 0 34 22 1 0 4 2 10 4 3 1 1 0 57 23 1 0 0 9 50 5 3 1 0 2 42 24 0 5 0 1 60 6 3 0 0 4 50 25 0 3 3 0 21 7 2 1 2 1 22 26 0 3 2 2 6 8 2 1 1 3 7 27 0 2 4 0 44 9 2 0 3 1 45 28 0 2 3 2 29 10 2 0 2 3 30 29 0 2 2 4 14 11 2 0 1 5 15 30 0 1 4 2 52 12 2 0 0 7 0 31 0 1 3 4 37 13 1 4 0 1 18 32 0 1 2 6 22 14 1 3 1 1 41 33 0 1 1 8 7 15 1 3 0 3 26 34 0 0 4 4 60 16 1 2 1 3 49 35 0 0 3 6 45 17 1 2 0 5 34 36 0 0 2 8 30 18 1 1 4 0 2 37 0 0 1 10 15 19 1 1 1 5 57 38 0 0 0 12 0 with � = [�01...�011�11�21...�24�31...�310...�423]t constraints (6-9) show that strips with lengths of 164 mm, 235 mm, 280 mm, and 282 mm are used in the �rst and second stages of the cutting pattern. constraints (10-13) show that items measuring 164×100 mm2, 235×185 mm2, 280×250 mm2, and 282×208 mm2 are produced not less than 20 sheets. constraint (14) shows the nonnegative solution. by using lindo 13.0, the solution of model with objective function (5) and constraints (6-14) shows that in the �rst stage �01 = 3 and �07 = 1 which means the 1st and the 7tℎ pattern will be used 3 times and once respectively. on the other side, in the second stage, the solution shows that �49 = 6 which means the 9th pattern on the fourth stripe will be used six times. the objective function z = 4 means that there are 4 pieces of the �rst stock of sizes 1022×1200 mm2. the gilmore and gomory model for the stock 1200×1200 mm2 can be seen in equation (15) and constraints (10-13) to constraints (16-20). minimize z = 14 ∑ j=1 �0j (15) subject to 2(�01 +�02 +�04 +�05 +�06) +�09 +�010 + 3�013 + 7�014 −�11 = 0 (16) 2�03 +2�05 +3�06 +�07 +2�09 +3�010+�011+5�012+3�013− 4 ∑ j=1 �2j = 0 (17) �02 + 2�04 + �05 + 3�08 + 2�09 + �010 + �011 − 10 ∑ j=1 �3j = 0 (18) 3�01 + 2�02 + 2�03 + �04 + �05 + �06 + �07 − 23 ∑ j=1 �4j = 0 (19) with equations (10)-(13) � ≥ 0 (20) with � = [�01...�014�11�21...�24�31...�310�41...�423]t by using lindo 13.0, the solution of model with objective function (15) and constraints (16-20) shows that the 1st and the 3rd pattern will be used once and three times respectively in the �rst stage. while in the second stage, we will use four times the 4tℎ pattern on the second stripe and once of the 18tℎ or the 23rd pattern on the fourth stripe. the gilmore and gomory model for the stock 1200×1500 mm2 can be seen in equation (21) and constraints (22-30). © 2020 the authors. page 125 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 table 5. cutting patterns according to the width of 1500 mm the the width for each cut the the width for each cut j-th cutting cutting pattern (mm) loss j-th cutting cutting pattern (mm) loss pattern 250 208 185 100 (mm) pattern 250 208 185 100 (mm) 1 6 0 0 0 0 34 1 2 1 6 49 2 5 1 0 0 42 35 1 2 0 8 34 3 5 0 0 2 50 36 1 1 5 1 17 4 4 1 1 1 7 37 1 1 4 3 2 5 4 0 2 1 30 38 1 1 1 8 57 6 4 0 1 3 15 39 1 1 0 10 42 7 4 0 0 5 0 40 1 0 6 1 40 8 3 3 0 1 26 41 1 0 5 3 25 9 3 2 1 1 49 42 1 0 4 5 10 10 3 2 0 3 34 43 1 0 0 12 50 11 3 1 1 3 57 44 0 7 0 0 44 12 3 1 0 5 42 45 0 6 0 2 52 13 3 0 4 0 10 46 0 5 0 4 60 14 3 0 0 7 50 47 0 4 3 1 13 15 2 2 3 0 29 48 0 3 4 1 36 16 2 2 2 2 14 49 0 3 3 3 21 17 2 1 4 0 52 50 0 3 2 5 6 18 2 1 3 2 37 51 0 2 5 1 59 19 2 1 2 4 22 52 0 2 4 3 44 20 2 1 1 6 7 53 0 2 3 5 29 21 2 0 4 2 60 54 0 2 2 7 14 22 2 0 3 4 45 55 0 1 4 5 52 23 2 0 2 6 30 56 0 1 3 7 37 24 2 0 1 8 15 57 0 1 2 9 22 25 2 0 0 10 0 58 0 1 1 11 7 26 1 5 1 0 25 59 0 0 8 0 20 27 1 5 0 2 10 60 0 0 7 2 5 28 1 4 2 0 48 61 0 0 4 7 60 29 1 4 1 2 33 62 0 0 3 9 45 30 1 4 0 4 18 63 0 0 2 11 30 31 1 3 2 2 56 64 0 0 1 13 15 32 1 3 1 4 41 65 0 0 0 15 0 33 1 3 0 6 26 © 2020 the authors. page 126 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 table 6. optimal solution type of stock stage of cutting the gilmore and gomory model the set covering modeltype of pattern number of cutting type of pattern number of cutting stock 1 first stage the 1st 3 the 2nd 12 the 7th 1 the 4th 3 the 8th 6 the 9th 2 second stage stripe 4 stripe 3 the 9th 6 the 3rd 1 the 9th 4 the 10th 1 stripe 4 the 9th 6 the 18th 1 stock 2 first stage the 1st 1 the 1st 5 the 3rd 3 the 2nd 1 the 5th 13 the 8th 2 second stage stripe 4 stripe 2 the 18th 1 the 4th 5 the 23th 1 stripe 4 the 10th 2 the 23th 7 stock 3 first stage the 1st 1 the 1st 4 the 5th 1 the 5th 12 the 8th 1 the 8th 4 second stage stripe 3 stripe 1 the 16th 1 the 1st 2 stripe 5 stripe 2 the 15th 6 the 3rd 3 stripe 3 the 16th 4 stripe 4 the 15th 3 minimize z = 14 ∑ j=1 �0j (21) subject to 2(�01+�02+�04+2�07+�08+2�011)+�03+�05+�06+�09+�010+3�013+7�014−�11 = 0 (22) 2(�03 +�05 +�09)+3(�06 +�010+�013)+�07 +�011+5�012− 6 ∑ j=1 �2j = 0 (23) �02 + 2�05 + �05 + 3�08 + 2�09 + �010 + �011 − 15 ∑ j=1 �3j = 0 (24) 3�01 + 2�02 + 2�03 + 7 ∑ j=45 �0j − 43 ∑ j=1 �4j = 0 (25) 15�11 + 13�21 + 11�22 + 9�23 + 7�24 + 2�25 + 12�31 + 5�32+ 3�33 + �34 + 10�35 + 8�36 + 6�37 + 4�38 + 2�39 + 7�310 + 5�312 + 3�313+ �314 + 2�315 + 11�41 + 9�42 + 7�43 + 5�44 + 7�45 + 5�46 + 3�47 + �438 + 5�49 +3�410 + �411 + �412 + 4�413 + 2�414 + 10l�416 + 8�417 + 3�418+ �419 + 8�410 + 6�421 + 6�422 + 4�423 + 2�424 + �439 + �440 + �441 ≥ 20 (26) © 2020 the authors. page 127 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 �21 + 2�314 + �41 + 2�42 + 7�25 + 8�26 + 4�32 + 5�33 + 6�34 + �36 + 2�37 + 3�38+ 4�39 + 4�311 + �313 + 2�314 + �41 + 2�42 + 3�43 + 2�315 + 11�41+ 9�42 + 4�44 + 2�45 + 3�46 + 7�46 + 5�48 + 2�439 + 3�410 + 3�410+ 4�411 + 3�412 + 4�42 + 5�43 + 6�44 + �46 + 4�47 + 5�48 + �410+ 3�412 + �417 + 4�418 + 5�419 + �421 + �423 + 2�424 + �430 + 2�431+ 3�432 + 4�433 + 2�434 + 3�424 + �437 + �439 + �441 ≥ 20 (27) 4 ∑ j=1 �4j + 2 9 ∑ j=5 �3j + 3 11 ∑ j=10 �3j + 4 14 ∑ j=12 �3j + 5�315 + 6�316 + 7�317+ 33 ∑ j=16 �4j + 2 35 ∑ j=30 �4j + 3 40 ∑ j=36 �4j + 4�441 + 5�442 ≥ 20 (28) 4 ∑ j=1 �4j + 2 8 ∑ j=5 �4j + 3 11 ∑ j=9 �4j + 4�412 + 5�413 + 6�414 + 7�414 + 33 ∑ j=16 �4j + 33 ∑ j=16 �4j + 2�434 + 2�435 + �436 + �437 + �438 + 2�439 + 3�440 + �441 + �442+ ≥ 20 (29) � ≥ 0 (30) with � = [�01...�014�11�21...�26�31...�316�41...�442]t 16tℎ pattern will be used once on the third stripe in the second stage and the 15th patterns on the fourth stripe will be used six times. 3.3 set covering model set covering model can be seen in equation (31). minimize z = n ∑ j=1 xj subject to n ∑ j=1 aijxj ≥ b1, i = 1,2, ..., m (31) xj�z+, i = 1,2, ..., n whereas xj is the number of jtℎ cutting pattern aij is the number of itℎ items which cut in jtℎ cutting pattern bi is the number of demands from all cutting patterns, then formulated the set covering model. the model for a stock size of 1022 mm × 1200 mm is: minimize z = x1 + x2 + x3 + x4 + x5 + x6 + x7 + x8 + x9 + x10 + x11 (32) subject to x1 + x2 + x3 + x4 + 3x6 + x7 + 3x9 + 3x10 + 6x11 − y1 ≥ 20 (33) x3 + 3x5 + x6 + 3x8 + x9 + 2x10 − 5 ∑ i=2 yi ≥ 20 (34) x2 + 2x4 + 3x7 + x8 + x9 − 15 ∑ i=6 yi ≥ 20 (35) 3x1 + 2x2 + 2x3 + x4 + x5 + x6 − 38 ∑ i=16 yi ≥ 20 (36) 121 + 10y2 + 8y3 + 6y4 + 4y5 + 8y6 + 6y7 + 4y8 + 2y9 + 4y10+ 2y11 + 2y13 + y15 + 9y16 + 2y17 + 7y19 + 5y20 + 5y22 + 3y23+ 3y24 + y25 + y26 + 7y27 + 5y28 + 3y29 + y30 + 3y31 + y32 + 4y33+ 2y34 + 2y37 ≥ 20 (37) y2 + 2y3 + 3y4 + 4y5 + y6 + 2y7 + 3y8 + 4y9 + 2y10 + 3y11 +4y12 + 2y13 + 3y14 + 4y17 + 5y18 + y20 + 4y21 + y23+ y25 + y28 + 2y29 + 3y30 + y31 + 2y32 + y35 + y38 ≥ 20 (38) y6 + y7 + y8 + 2y9 + 2y10 + 2y11 + 2y12 + 3y13 + 4y14 +4y15 + y26 + y27 + y28 + y29 + y30 + y31 + y32 + y33+ 2y34 + 2y35 + 3y36 + 3y37 + 3y38 ≥ 20 (39) y16 + y17 + y18 + y19 + 2y20 + 2y21 + 2y22 + 3y23 +3y24 + 5y25 + y26 + y27 + y28 + 2y29 + 2y30 + 3y31 +3y32 + 4y33 + y34 + y35 + y36 + y37 + 2y38 ≥ 20 (40) xj,yj ≥ 0 and integer, j = 1, 2, . . . , 38. by using the lingo 13.0, the optimal solutions of model with objective function (32) and constraints (33-40) are x2 = 12,x4 = 3,x9 = 2,x8 = y24 = 6,y1 = y8 = y15 = y33 = 1,y14 = 4 with the objective value z = 23 based on the solutions, from the �rst stage of cutting (cutting based on length), the 2nd cutting pattern was cut 12 times, the 4tℎ cutting pattern was cut 3 times, the 8tℎ and the 9tℎ cutting pattern were cut 6 times and twice respectively. in the second stage of cutting, the �rst cutting pattern was cut once in the �rst stripe. none cutting pattern was chosen in the second stripe. in the third stripe, the 3rd and 10tℎ were used once each and the 9tℎ cutting pattern was used four times. only the 18tℎ cutting pattern was used once in the fourth stripe. set covering model for stock size of 1200 mm × 1200 mm is: © 2020 the authors. page 128 of 130 octarina et. al. science and technology indonesia, 5 (2020) 121-130 minimize z = x1+x2+x3+x4+x5+x6+x7+x8+x9+x10+x11+x12+x13+x14 (41) 2x1+2x2+x3+2x4+x5+x6+4x7+2x8+x9+x10+4x11+3x13+7x14−y1 ≥ 20 (42) 2x3+2x5+3x6+x7+2x9+3x10+x11+5x12+3x13− 5 ∑ i=2 yi ≥ 20 (43) x2 + 2x4 + x5 + 3x8 + 2x9 + x10 + x11 − 5 ∑ i=6 yi ≥ 20 (44) 3x1 + 2x2 + 2x3 + x4 + x5 + x6 + x7 − 38 ∑ i=6 yi ≥ 20 (45) with equations (37-40) xj,yj ≥ 0 , and integer j = 1, 2, . . . , 38. the optimal solutions of model with objective function (41) and constraints (37-40) to contraints (42-45) are x1 = 5,x2 = 1,x5 = 13,x8 = 2,y5 = 5,y25 = 2,y38 = 7 with objective value z=21. the �rst cutting pattern (cut 5 times), the second cutting pattern (cut once), the 5tℎ cutting pattern (cut 13 times), and the 8tℎ cutting pattern (cut twice) were used in the �rst stage. for the second stage, it used the second and fourth stripe. the 4tℎ cutting pattern was used 5 times in the second stripe. the 10tℎ cutting pattern was used twice and the 23rd cutting pattern was used 7 times each in the fourth stripe. set covering model for stock size of 1200 mm × 1500 mm is minimize (41) subject to constraints (42) 2x3+2x5+3x6+x7+2x9+3x10+x11+5x12+3x13− 7 ∑ i=2 yi ≥ 20 (46) x2 + 2x4 + x5 + 3x8 + 2x9 + x10 + x11 − 65 ∑ i=8 yi ≥ 20 (47) 3x1 + 2x2 + 2x3 + x4 + x5 + x6 + x7 − 65 ∑ i=24 yi ≥ 20 (48) with equations (37-40) xj,yj ≥ 0 and integer j = 1, 2, . . . , 65. the optimal solution of model with objective function (41) and constraints (37-40) to contraints (42), (46-48) are x1 = 4,x5 = 12,x8 = 4,y1 = 2,y7 = 3,y23 = 4,y38 = 3 with objective value z=20 . in the �rst stage, it used the 1st cutting pattern (4 times), the 5tℎ cutting pattern (12 times), and the 8tℎ cutting pattern (4 times). otherwise, in the second stage, it used the 1st cutting pattern (twice) in the �rst stripe, the 3rd cutting pattern (3 times) in the second stripe, the 16tℎ cutting pattern (4 times) in the third stripe and the 15tℎ cutting pattern (3 times) in the fourth stripe. for details, the summary of optimal solutions between the gilmore and gomory model and the set covering model can be seen in table 6. from both of the models, the set covering model yields more patterns combination than the gilmore and gomory model. the more patterns combination created, the more stock used, and the trim loss will be bigger. but, the gilmore and gomory model uses less stock than the set covering model. 4. conclusions from the result and discussion, it can be concluded that the gilmore and gomory model and the set covering model can be implemented in the cutting stock problem, especially in 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(2001). pattern generating procedure for the cutting stock problem. international journal of production economics, 74(1-3); 293–301 umetani, s. and m. yagiura (2007). relaxation heuristics for the set covering problem(special issuethe 50th anniversary of the operations research society of japan). journal of the operations research society of japan, 50(4); 350–375 © 2020 the authors. page 130 of 130 introduction experimental section data methods results and discussion pattern generation the gilmore and gomory model set covering model conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 2, april 2020 research paper a hidden markov model for forecasting rainfall data availability at the weather station in west sumatra rahmawati ramadhan1, dodi devianto1* 1department of mathematics, andalas university, limau manis campus, padang 25163, indonesia *corresponding author: ddevianto@sci.unand.ac.id abstract indonesia is a maritime continent in southeast asian, laying between indian ocean and pacific ocean. this position intensely a�ects the level of rainfall in indonesia, especially west sumatra. the availability of rainfall data can form a markov chain which its state is not able to be observed directly (hidden), is called the hidden markov model (hmm). the purposes of this research are to predict the hidden state of the availability of rainfall data using decoding problems and to find the best state sequence (optimal) by using viterbi algorithm, and also to predict probability for the availability of rainfall data in the future by using the baum welch algorithm in the hidden markov model. this research uses secondary data with a period of one day from the availability of rainfall data at the minangkabau meteorological station, padang pariaman climatology station, and silaing bawah geophysics station from january 2018 to july 2019. the results of the prediction show that the hidden markov model can be used to predict the probability of rainfall data availability. the results for the availability of the highest rainfall data for one day ahead is at the padang pariaman climatology station, with a probability of 0.36, followed by minangkabau meteorological station is 0.35, and silaing bawah geophysics station is 0.29. the result has shown for the next one day period the probability of rainfall data available from the three stations will be available following the viterbi algorithm. keywords hidden markov model, rainfall, decoding problem received: 12 february 2020, accepted: 03 april 2020 https://doi.org/10.26554/sti.2020.5.2.34-40 1. introduction a water particle that falls to the earth’s surface through a series of hydrological processes is the occurrence of rain. meanwhile, rainfall is the height of the rainwater that falls to the earth’s surface to a �at within a certain period. many say the least precipitation in an area in�uenced by several factors, including factors latitude, altitude, and distance from the source of the water, the wind, the mountain areas, the temperature di�erence, and the total land area. in analyzing the availability of rainfall in the future maybe associated with a stochastic process, where the problem is related to the chance of future events that they cannot be predicted directly on the availability of rainfall data. states of availability of rainfall data are uncertain and subject to change, and it is assumed there are some unobserved circumstances; it can be modeled by hidden markov model (hmm). hmm is a broadening of the markov chain in which the state cannot be observed directly (hidden), but can only be observed through a set of other observations. in hmm, there are three fundamental problems to be solved that problem evaluation, decoding problems, and learning problems. based on research by thyer and kuczera (2003), they have discussed a calibration model with bayesian approach on rainfall data by using hmm, the same thing was done by sansom (1998) for the data breakpoint. some research that uses inhomogeneous hmm and nonparametric model reduction of rainfall events has been carried out also by mehrotra and sharma (2005); robertson et al. (2004); greene et al. (2011); pineda and willems (2016). furthermore, there are some hmm models introduced by previous researchers, the abundance of species in the river with hmm with negative binomial model approach discussed by spezia et al. (2014). according to research conducted in xia and tang (2019); li et al. (2018); bathaee and sheikhzadeh (2016), hmm also associated with bayesian analysis. meanwhile, in the case of time series, there is a lot of research that studies the hidden markov models, one of which discusses the most reliable classi�cation of multivariate time series as described antonucci et al. (2015), and categories with hmm multiple time series by colombi and giordano (2015). also besides, hmm also is used in the �nancial case is to predict trends in the time series as discussed in zhang et al. (2019) and to predict the probability https://doi.org/10.26554/sti.2020.5.2.34-40 ramadhan et. al. science and technology indonesia, 5 (2020) 34-40 of the changes of the exchange rate as discussed in ramadhan et al. (2020). based on the research of devianto et al. (2015b), the techniques to build models using �nancial data can be used autoregressive fractionally integrated moving average (arfima). furthermore, the enumeration models have been developed with an exponential distribution characterization approach described in devianto (2016); devianto et al. (2015a,c). according to research conducted in stoner and economou (2019), it is illustrated how the hidden markov framework could be adapted to construct a compelling model for sub-daily rainfall, which is capable of capturing all of these essential characteristics well. several homogenous hidden markov models (hmms) were developed to forecast droughts using the standardized precipitation index, spi, at short-medium term, as discussed in khadr (2016). the hidden markov sequence was assigned to represent the recurrence of mast years, as described in tseng et al. (2020). model availability of rainfall data can be formed into a hidden state hmm with attention. in this study, there are three fundamental problems to be solved that are evaluations problem, decoding problems, and learning problems. the results can provide information about the availability of rainfall data in particular areas of west sumatra in the future. historical information about the availability and the accuracy of rainfall data will be very helpful in predicting climate change and irregularities. in addition, by obtaining an overview of future weather conditions, the speci�c policy considering water supply, plant performance and yield can be estimated for better preventive of resources for community. 2. experimental section 2.1 materials a sequence of events that ful�ll the legal requirement of probability, where every value randomly changed against time. a stochastic process predicted the properties of the future depend on the properties of the current conditions based on their characteristics in the past called a markov chain (ross, 1996). stochastic process xn(t) is a series of random variables that change with the time of observation t�t, and a stochastic process xn is said to have markov properties if, p(xn+1 = j|xn = i,xn−1 = in−1, ....,x0 = i0) (1) = p(xn+1 = j|xn = i) for time and for every n = 0, 1, 2, ... and for every j, i, in−1, ..., i1, i0 hmm is a stochastic model where the system is assumed to be a markov process with hidden states. if x = (x1,x2, . . .) is a markov process and o = (o1,o2, . . .) is a function of x , then is a hidden markov model which can be observed through o, or can be written to a function f . the parameter x represents the state process that is hidden, while parameter o states an observation room that can be observed. the elements of the hidden markov model are: 1. the number of hidden state elements (hidden state) represented by n as the number of states which the probability of a denoted state space s = (s1,s2, . . . ,sn ) and the state at the time t denoted by xt, t = 1, 2, . . . ,t 2. the number of observations (observation) of each state represented by m, where probability every state represented by v = v1,v2, . . . ,vm and space observation represented by o = (o1,o2, . . . ,ot ), which t is the length of the observation data. 3. the transition probability matrix a = [aij] where aij is an element of a which is the conditional probability of the state at the time , given the state at the time , that is aij = p(xn+1 = j|xn = i) (2) for 1 ≤ i, j ≤ n 4. observation probability distribution at the time t, at state j, commonly known as emission matrix b = [bik] (3) where bik = p(ot = vk|xt = i) (4) for 1 ≤ j ≤ n , 1 ≤ t ≤ t and 1 ≤ k ≤ m 5. the initial state distribution represented by �(i) where �(i) = p(x1 = i, 1 ≤ i ≤ n) (5) so hmm can be written in the notation �=(a,b,�) where a is expressed by the matrix of transition probability, b a chance observation matrix known as emission matrix, and � is the distribution of the initial state. there are three special algorithms that can be solved by hmm method, namely: a) evaluation problem to calculate the probability of the observation sequence p(o|�) requires forward algorithms and backward algorithms (bain and engelhardt, 1992). steps to resolve with the advanced algorithm are as follows: i. initial step in this initial step, we determined the initial observation probability �1(i) which ends at state at the time if it is known a sequence of preliminary observations o1 is as follows: �(i) = �(i)bi(oi) (6) for 1 ≤ i ≤ n ii. induction step in this induction step, we determined the total observation probability �t+1(j) which end in state i at the time i = 2, 3, 4, ..., if known a sequence of observations o1,o2, ...,or is as follows: �t+1(j) = { n ∑ i−1 �t(i)aij}bj(ot+1) (7) for j = 1, 2, .....n , t = 1, 2, ...,t iii. termination step on termination of this step, we determined the total combined odds of observation and the hidden © 2020 the authors. page 35 of 40 ramadhan et. al. science and technology indonesia, 5 (2020) 34-40 state when known a model so that it is known probability observation sequence p(o|�), as follows: p(o|�) = n ∑ i−1 �t (i) (8) next, calculate the probability of observation by using a backward algorithm �t(i), namely with as following steps : i. initial step in this initial step, the initial observation probabilities otherwise equal to one, this is because it is assumed i is the �nal state, and zero for the other can be expressed as �t(i) = 1 (9) for 1 ≤ i ≤ n ii. induction step in this induction step, we determined the total observation probabilities for t < 1 , as follows: �t(i) = n ∑ j−1 aijbj(ot+1)�t+1(j) (10) for t = t − 1,t − 2, ...1 and i = 1, 2, ...,n iii. termination step in this step, the total odds will be determined combination of observation and the hidden state when known a model so that it is known probabilities observation sequence p(o|�), as follows p(o|�) = n ∑ i−1 bi(1)�(1)�1(i) (11) b) decoding problem decoding problem, this decoding step is to �nd the best state sequence (optimal) associated with the observation of o and a model of �, which has also been known. this problem can be solved by the viterbi algorithm. steps in the viterbi algorithm to determine the best state sequence are as folows i. initial step in this initial step, it will be determined the greatest probabilities throughout t the �rst observation and ends in state i to t = 1, as follows: �1(j) = bi(o1)�(i) 't(i) = 0, 1 ≤ i ≤ n (12) ii. recursion step in this recursion step, it will be determined greatest probabilities throughout t the �rst observation and ends in state i for t > 2 , as follows �t(j) = max1≤i≤n[�t−1(i),aij]bj(ot) 't(j) = arg max1≤i≤n[�t−1(i),aij] (13) for 2 ≤ t ≤ t and 1 ≤ j ≤ n iii. termination step on termination of this step, it will be determined the greatest probabilities throughout t the �rst observation and ends in state i, as follow p+ = max 1≤i≤n [�t (i)] x+t = arg max1≤i≤n[�t (i)] (14) iv. backtracking step in this last step, it will be determined the best state sequen ce, as follow x+t = 't+1(x+t+1), t = t − 1,t − 2, ..., 1 (15) c) learning problem this problem estimates the best model to explain a sequence of observations, where the changing parameters of hmm, � = (a,b,�) so that p(o|�) becomes the maximum. in the baumwelch algorithm, also de�ned four variables, namely: variable forward (forward), variable backward (backward), variable �t(i, j), and the variable t(i). forward variable and backward variable will be used in the calculation of the variable �t(i, j) and the variable t(i), so the estimation formula learning problem is as follows: �̂(i) = t(i), 1 ≤ i ≤ n âij = ∑t−1t=i �t(i, j) ∑t−1t=1 t(i) , 1 ≤ i ≤ n, 1 ≤ j ≤ n b̂ij = ∑t=1t=1,o=j t(i) ∑t=1t=1 t(i) , 1 ≤ j ≤ n, 1 ≤ k ≤ m (16) where �̄(i) is the estimated value of initial state, âij is the matrix of the estimated value of transition probabilities, and b̂ij is the matrix of the estimated value of emission matrix. 2.2 methods in this study, the data to be used only calculates rainfall data for 17 months on january 1, 2018, to july 31, 2019, with a period of one day, from the contribution of rainfall data at the minangkabau meteorological station (mm station), padang pariaman climatology station (ppc station), and silaing bawah geophysics station (sbg station), it is obtained at the website address dataonline.bmkg.go.id with the amount of data used in one station is 570. presentation of rainfall data in diagram form can be seen from the figure 1 as follows based on figure 1, it can be seen that the highest availability of rainfall data is at the mm station at 287 data, followed by the ppc station at 231 data and the sbg station at 219 data. the highest number of unavailable data of rainfall during the period © 2020 the authors. page 36 of 40 ramadhan et. al. science and technology indonesia, 5 (2020) 34-40 figure 1. rainfall data availability of research is at sbg station with 134 data, followed by ppc station with 122 data, and mm station with 66 data. from the three stations, each has 7 data that were not measured. this research uses hmm for forecasting the availability of rainfall data. that will be analyzed is rainfall data with predictions of probability rainfall on the next period, as follows: 1. take rainfall data by a period of one day. the numbers of data have been observed in the range of time of 570 days. 2. determine the transition probability matrix needed exchange rate by using the following formula as a probability. p(a) = n(a)n(s) (17) where n(a) is the number of elements in a and n(s) is the total number of elements in s [22]. 3. determine elements of hmm. 4. analyze the elements of hmm that have been able to use where the hmm is calculated the probability of availability of an observation by using forward-backward algorithm, then it is followed by determining the sequences of hidden state by using the viterbi algorithm, and it is predicting the hmm parameters by using the baum-welch algorithm. 5. make the interpretations or conclusions from the results that have been obtained. 3. result and discussion 3.1 the importance of rainfall data availability by controller graph of exponentially weighted moving average (ewma) in this study, the ewma control chart is used to see whether there is extreme rainfall or non-controlled data, such that the availability of rainfall data will be very crucial to observe. rainfall data had been taken from the weather stations in west sumatera in 2018. the following chart is ewma control of rainfall data. based on figure 2. this shows that there is extreme rainfall on the day of observation to-88, 89, 90, 91, 102, 103, 107, 108, 144, 145, 146, 147, 148, 238.239, 240, 241, 252, 271, 316, 336, 337, 338, 339, 340, 341, 364, 365, and 366. this means that there are 28 days with rainfall that is not controlled or extreme. this condition figure 2. rainfall ewma control charts have indication there are changes in rainfall throughout the day, where there is a condition of very high rainfall or otherwise. the availability of rainfall data in these circumstances is very important in order to be taken to minimize losses related to changes in precipitation. therefore, it is necessary to build a model of the availability of rainfall data in every weather station is west sumatera by using hmm. 3.2 elements of the hidden markov model the elements that must be determined to solve the case of forecasting the availability of rainfall data with hmm, as follows: 1. suppose n , is the number of hidden states, with state space a = (s1,s2, . . . ,sn ) and the state at time t is expressed by xt . in this case of rainfall data availability in mm station, ppc station, and sbg station. the hidden state is available, unavailable, and not measurement. so in this case study n = 3 or can be written as s1 = p(available), s2 = p(unavailable), s3 = p (no measurement). for example , xt = 1, it states that the state is in a state of rainfall data available. 2. let m, is the number of observations of each state, the observation space o = (o1,o2, . . . ,ot ) and the probability every observations expressed by v = (v1,v2, . . .vm), in this study m = 3, the mm station as v1, ppc station as v2, and sbg station as v3. 3. let a = aij = p(xt+1 = j|xt = i) where a is the probability of availability of rainfall data over a range of values to j on day t +1 if it is known on day t is in the range value to i thus formed matrix probability are: a = [aij] = ⎡ ⎢ ⎢ ⎣ a11 a12 a13 a21 a22 a23 a31 a32 a33 ⎤ ⎥ ⎥ ⎦ a) transition probability matrix mm station data a = [aij] = ⎡ ⎢ ⎢ ⎣ 0.79 0.19 0.02 0.58 0.41 0.01 0.46 0.18 0.36 ⎤ ⎥ ⎥ ⎦ © 2020 the authors. page 37 of 40 ramadhan et. al. science and technology indonesia, 5 (2020) 34-40 b) transition probability matrix ppc station data a = [aij] = ⎡ ⎢ ⎢ ⎣ 0.74 0.25 0.01 0.46 0.52 0.02 0.42 0.25 0.33 ⎤ ⎥ ⎥ ⎦ c) transition probability matrix sbg station data a = [aij] = ⎡ ⎢ ⎢ ⎣ 0.64 0.35 0.01 0.47 0.50 0.03 0.33 0.42 0.25 ⎤ ⎥ ⎥ ⎦ 4. emission matrix b = [bik], the conditional probability matrix observation vk if the process is in state j, matrix emissions observations mm station, ppc station, and sbg station are as follows: a = [aij] = ⎡ ⎢ ⎢ ⎣ 0.74 0.64 0.56 0.24 0.34 0.42 0.02 0.02 0.02 ⎤ ⎥ ⎥ ⎦ 5. suppose �(i) is the initial state distribution, in case of the availability of rainfall data are assumed: �(1) = p(available), �(2) = p(unavailable), �(1) = p(no measurement). initial matrix for mm station, ppc station, and sbg station are as follows: a) initial matrix for mm station: � = ⎡ ⎢ ⎢ ⎣ 0.70 0.27 0.03 ⎤ ⎥ ⎥ ⎦ b) initial matrix for ppc station: � = ⎡ ⎢ ⎢ ⎣ 0.62 0.36 0.02 ⎤ ⎥ ⎥ ⎦ c) initial matrix for sbg station: � = ⎡ ⎢ ⎢ ⎣ 0.64 0.34 0.02 ⎤ ⎥ ⎥ ⎦ 3.2.1 evaluation problem with forward and backward algorithm for the �rst problem on hmm, will be calculated the probability models � = (a,b,�) that represented by p(o|�) or probabilities of observation sequence o = (o1, o2, o3). this probability can be determined using the forward and backward algorithm. p(o = mkg|�) = n ∑ i=n at(i) = a4(1) + a4(2) + a3(3) = 0.091 p(o = mkg|�) = n ∑ i=n �1(i)�(i)bi(o1) = �1(1)�(i)b1(o1)+�1(2)�(2)b2(o1)+�1(3)�(3)b3(o1) = 0.091 based on the results of the backward algorithm obtained are consistent with the obtained solution of the forward algorithms, namely the observation probabilities at 0.091. 3.2.2 decoding problem with viterbi algorithm for this problem decoding problem is how to determine the optimal sequence hidden state, in this case is available, not available, or no measurement with the sequence of observations that have been assumed. the viterbi algorithm consists of three steps, including the following: x∗1 = 1,x∗2 = 1,x∗3 = 1 it means the most suitable sequence of available, unavailable, or no measurement rainfall data sequence for august 2019 is more widely available. 3.2.3 learning problem with baum welch algorithm to calculate the parameters of hmm prediction using baum welch algorithm, it can be de�ned a new variable �t(i, j), that probability process in state i at the time t + 1. it follows �̂ = ⎡ ⎢ ⎢ ⎣ 1(1) 1(2) 1(3) ⎤ ⎥ ⎥ ⎦ = ⎡ ⎢ ⎢ ⎣ 0.9765 0.1078 7.201x10−4 ⎤ ⎥ ⎥ ⎦ the value at t(i) for t = 1 is an estimated of early chance. that means the value of p(o|�̂) > p(o|�) has completed, then the probability process in a state of rainfall data availability will be available by 0.9765, it will not be available is equal to 0.1078, and the estimation of the initial probability that no measurements is equal to 7.201 x 10-4. meanwhile, for a prediction of the transition matrix aij that was written with âij is the ratio between the amount of displacement of state probability to state the amount of displacement in the state probability in the state i , as follows: âij = ⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ∑tt−1 �t(1, 1) ∑tt−1 t(1) ∑tt−1 �t(1, 2) ∑tt−1 t(1) ∑tt−1 �t(1, 3) ∑tt−1 t(1) ∑tt−1 �t(2, 1) ∑tt−1 t(2) ∑tt−1 �t(2, 2) ∑tt−1 t(2) ∑tt−1 �t(2, 3) ∑tt−1 t(2) ∑tt−1 �t(3, 1) ∑tt−1 t(3) ∑tt−1 �t(3, 2) ∑tt−1 t(3) ∑tt−1 �t(3, 3) ∑tt−1 t(3) ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ âij = ⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ 2.3702 2.7670 0.3957 2.7670 1.013x10−3 2.7670 0.3064 0.4399 0.1331 0.4399 3.621x10−4 0.4399 1.157x10−3 2.273x10−3 10−3 2.273x10−3 10−5 2.273x10−3 ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ âij = ⎡ ⎢ ⎢ ⎣ 0.85 0.14 0.01 0.69 0.3 0.01 0.51 0.14 0.35 ⎤ ⎥ ⎥ ⎦ the matrix â(ij) is an estimator for the transition matrix aij . the matrix â(ij) describes to reach a value p(o | �̂) > © 2020 the authors. page 38 of 40 ramadhan et. al. science and technology indonesia, 5 (2020) 34-40 p(o | �) , then the transition probabilities of rainfall data at the state of availability will be the probability of the change conditions of "available" to "available" is 0.85, from "available" to "unavailable" is 0.14, from "available" to "no measurement" is 0.01. the probability of "unavailable" to "available" is 0.69, from "unavailable" to "unavailable" is 0.3, from "unavailable" to "no measurement" is 0.01. the probability for conditions as well as of "no measurement" to "available" is 0.51, "no measurement" to "unavailable" is 0.14, "no measurement" to "no measurement" is 0.35. likewise with predictions emission matrix bik , which is denoted by b̂ik obtained from a comparison of the number of states that produce k observations when the process is in state i with the number of the entire process is in state i so that the emission matrix estimators obtained as follows âij = ⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ∑tt−1,ot−1 t(1) ∑tt−1 t(1) ∑tt−1,ot−2 t(1) ∑tt−1 t(1) ∑tt−1,ot−3 t(1) ∑tt−1 t(1) ∑tt−1,ot−1 t(2) ∑tt−1 t(2) ∑tt−1,ot−2 t(2) ∑tt−1 t(2) ∑tt−1,ot−3 t(2) ∑tt−1 t(2) ∑tt−1,ot−1 t(3) ∑tt−1 t(3) ∑tt−1,ot−2 t(3) ∑tt−1 t(3) ∑tt−1,ot−3 t(3) ∑tt−1 t(3) ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ âij = ⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ 0.9765 2.7670 0.9961 2.7670 0.7944 2.76700.1078 0.4399 0.1298 0.4399 0.2023 0.4399 7.201x10−3 2.273x10−3 5.074x10−4 2.273x10−3 1.045x10−5 2.273x10−3 ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ âij = ⎡ ⎢ ⎢ ⎣ 0.35 0.36 0.29 0.25 0.29 0.46 0.32 0.22 0.46 ⎤ ⎥ ⎥ ⎦ the matrix âik is an estimator for the conditional probability of matrix b̂ik. the matrix describes that to achieve value p(o | �̂) > p(o | �) , then the chances of availability of rainfall data for the period one day ahead for mm station is 0.35, for ppc station is 0.36, for sbg station is 0.29. probabilities unavailability of rainfall data for the period of one day ahead for mm station is 0.25, for ppc station is 0.29, for sbg station is 0.46. probabilities no measurement on rainfall data for the period of one day ahead for mm station is 0.32, for ppc station is 0.22, for sbg station 0.46. based on the value of the probability of the rainfall data, sbg station has the greatest probability of unavailability and no measurements of rainfall data. it also impacts to sectors that have direct relation to the weather with rainfall conditions; one of them is in the agriculture sector that requires weather information to estimate an increase of output product. hence, it is necessary to improve human resources and also a good device to do measurements of rainfall data. 4. conclusions a stochastic process that meets the properties of probability in which the properties of future events depend on the properties of events in the present and the past and assumed there are properties of events that cannot be observed is called the hidden markov model (hmm). hidden markov model by the learning problems with baum-welch algorithm might be the probability for available data the highest rainfall in the period of the day to come in ppc station is 0.36. it is followed by probability available data is 0.35 in mm station and 0.29 in sbg station. as for decoding problem on hmm using the viterbi algorithm can be concluded that for the period of one day ahead might be probabilities rainfall data availability in mm station, ppc station, and sbg station will be more widely available. the results of probability rainfall data 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(1996). stochastic processes p. john wiley & sons sansom, j. (1998). a hidden markov model for rainfall using breakpoint data. journal of climate, 11(1); 42–53 spezia, l., s. cooksley, m. brewer, d. donnelly, and a. tree (2014). modelling species abundance in a river by negative binomial hidden markov models. computational statistics & data analysis, 71; 599–614 stoner, o. and t. economou (2019). an advanced hidden markov model for hourly rainfall time series. cornell university report: uk, arxiv: 1906.03846 thyer, m. and g. kuczera (2003). a hidden markov model for modelling long-term persistence in multi-site rainfall time series 1. model calibration using a bayesian approach. journal of hydrology, 275(1-2); 12–26 tseng, y.-t., s. kawashima, s. kobayashi, s. takeuchi, and k. nakamura (2020). forecasting the seasonal pollen index by using a hidden markov model combining meteorological and biological factors. science of the total environment, 698; 134246 xia, y.-m. and n.-s. tang (2019). bayesian analysis for mixture of latent variable hidden markov models with multivariate longitudinal data. computational statistics & data analysis, 132; 190–211 zhang, m., x. jiang, z. fang, y. zeng, and k. xu (2019). highorder hidden markov model for trend prediction in �nancial time series. physica a: statistical mechanics and its applications, 517; 1–12 © 2020 the authors. page 40 of 40 introduction experimental section materials methods result and discussion the importance of rainfall data availability by controller graph of exponentially weighted moving average (ewma) elements of the hidden markov model evaluation problem with forward and backward algorithm decoding problem with viterbi algorithm learning problem with baum welch algorithm conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 5, no. 4, october 2020 research paper performance of cans classification system for di�erent conveyor belt speed using naïve bayes yulia resti1*, firmansyah burlian2, irsyadi yani2 1department of mathematics, faculty of mathematics and natural science universitas sriwijaya, sumatera selatan, indonesia 2department of machanical engineering, faculty of engineering universitas sriwijaya, sumatera selatan, indonesia *corresponding author: yulia_resti@mipa.unsri.ac.id abstract the classification system in the sorting process in the can recycling industry can be made based on digital images by exploring the basic color pixel values of images such as r, g, and b as variable inputs. in real time, the classification of cans in the sorting process occurs when cans placed on a conveyor belt move at a certain speed. this paper discusses the performance of can classification systems using the naïve bayes method. this method can handle all types of variables, including when all variables are continuous. two types of conveyor belts are designed to get di�erent speeds, and all images of the cans are captured on both conveyor belts. two models of bayes naive are built on the basis of the di�erent distribution assumptions; the original model (all gaussian distributed) and the model based on the best distribution. performance of the classification system is built by dividing data into the learning data and the testing data with a composition of 50:50 in which each data is designed into 50 groups with di�erent percentages on each type of cans using sampling technique without replacement. the results obtained are first, the speed of the conveyor belt when capturing an image a�ects the pixel values of red, green, and blue and ultimately a�ects the results of the classification of cans. second, not all input variables are gaussian distributed. the classification system was built using assumption that the best distribution model for each input variable has the be�er average accuracy level than the model that assumes all input variables are gaussian distributed, and the accuracy level of classification on the first speed of conveyor belt with a gear ratio of 12:30 and a diameter of 35 mm has an accuracy that is be�er than the other speed, both on the original model and the model based on the best distribution. however, it is necessary to test more statistical distribution models to obtain significant results. keywords classification system, conveyor belt speed, naïve bayes received: 28 august 2020, accepted: 4 october 2020 https://doi.org/10.26554/sti.2020.5.4.111-116 1. introduction the automation technology of an industrial system that uses intelligent computing systems has continued to develop rapidly recently (kamboj et al. (2019); nikhil et al. (2017); oladapo et al. (2016); bargal et al. (2016); fluke (2015); rosenblat et al. (2014)) including the automation of sorting systems in the can recycling industry that uses object classi�cation techniques based on digital images (resti et al. (2018); resti et al. (2017b)). classi�cation of cans based on digital images of cans placed on a static conveyor belt can be seen in (resti et al. (2019); resti et al. (2017a); resti (2015); yani et al.; yani et al. (2009)). in real time, the classi�cation of cans in a sorting system occurs when cans placed on a conveyor belt move at a certain speed. obtaining a higher level of accuracy becomes important in the classi�cation system (sin & wang, 2019; arono� et al. (1982)). naïve bayes is one method that is widely used in classi�cation models (harzevili and alizadeh, 2018; agarwal et al. (2015)) especially digital object classi�cation models can be seen in (mansour (2018); pérez-díaz et al. (2017); nikhil et al. (2017); salinas-gutiérrez et al. (2010); jayech and mahjoub (2010)). this method can handle various types of input variables. when the input variables are continuous type, generally this method is built by assuming all input variables are gaussian distributed or a combination. the concept of conditional probability as in the bayes theorem with the naive assumptions in this method causes the calculation of posterior probabilities to be simpler (han et al. (2011); mitchell (1997)). for large datasets, this method often has a higher level of accuracy than other methods (adetunji et al. (2018); kini et al. (2015); loan (2006)), while for small datasets this method also perform powerful classi�er (mansour, 2018). this article discusses the performance of a can classi�cation https://doi.org/10.26554/sti.2020.5.4.111-116 resti et. al. science and technology indonesia, 5 (2020) 111-116 figure 1. the cans image capturing system system based on digital image of cans using the naïve bayes method. regarding real time, the image capturing was carried out on cans placed on conveyor belts. both types of conveyor belts are designed to get di�erent speeds using di�erent sizes and gear ratios, and all images of the cans are captured on both. we also propose two models of bayes; the original model and the model based on the best distribution. in the �rst model, all input variables are assumed to be gaussian distribution while in the second model, each input variable is assumed to be gamma or gaussian distribution according to statistical tests (wang and liu (2006); de wet (1980); stephens (1974); chakravarty et al. (1967)). performance of the classi�cation system is built by dividing data into the learning data and the testing data with a composition of 50:50 in which each data is designed into 50 groups with di�erent percentages on each type of cans using sampling technique without replacement. a highest level of accuracy is expected from the combination of these two speeds and the two models. 2. experimental section 2.1 methods the stages of this research are as follows: 1. designing 2 types of conveyor-belts, the �rst using a gear with a ratio of 12:30 and diameter of 35 mm, and the second, using a gear with a ratio of 14: 30 and diameter of 42 mm. these designs produced the speed of 0.181 m/s (the �rst conveyor-belt) and 0.086 m/s (the second conveyor-belt) respectively. 2. capturing images of the cans placed on the �rst conveyorbelt. the cans were captured using a web camera connected to a computer with the illumination of the light-emitting diode (led) lamp set at an angle of 30° as shown in figure 1. then, the cans are placed on the second conveyor belt and the image capturing proses is done the same way. furthermore, the can image data is processed using the rgb color model with a color depth of 8 bits where the region of interest in each image is obtained using image processing cropping techniques. data summary of the pixel values of r, g, and b of the two data are presented in table 1. 3. divide the data into learning data and testing data with a composition of 50:50, where each data is designed into 50 groups with di�erent percentages on each type of can using sampling technique without replacement. the percentage of cans in each table 1. data summary of the pixel values of r, g, and b statistics the 1st speed the 1st speed input variable input variable r g b r g b minimum 141.3 143.0 137.7 135.4 134.6 131.8 1st quartile 149.8 153.0 148.9 145.4 147.8 144.0 median 153.3 156.2 152.2 148.1 151.1 147.5 mean 155.4 156.4 152.7 150.4 151.5 148.3 3rd quartile 159.6 159.6 156.1 153.3 154.5 150.7 maximum 204.8 186.2 194.8 207.6 182.5 193.4 type of the learning data and the testing data, respectively is presented in table 2. table 2. design of the learning and the testing data percentage of cans in each type learning testing group can type group can type 1st 2nd 3rd 1st 2nd 3rd 1 33.6 35.2 31.2 1 25.6 31.2 43.2 2 32.8 32.0 35.2 2 34.4 32.8 32.8 3 30.4 33.6 36.0 3 28.8 32.8 38.4 4 28.0 30.4 41.6 4 31.2 36.0 32.8 5 38.4 22.4 39.2 5 20.8 44.0 35.2 ⋮ ⋮ ⋮ ⋮ ⋮ ⋮ ⋮ ⋮ 50 30.4 32.0 37.6 50.0 28.8 34.4 36.8 4. applying the naive bayes method [23-24] to model the can classi�cation system. let pixel values from each of the red, blue, and green colors for the k-th conveyor belt type be the input variables that denoted as r k ,g k ,b k and the three types of cans are food cans, beverage cans, and non-food and beverage cans be the output variables that denoted as t jk . a can is classi�ed as a can of j-th can type, if the can has the greatest posterior probability in the j-th can type as written in (1). p(t jk |r k ,g k ,b k ) = p(r k ,g k ,b k |t jk )p(t jk ) p(r k ,g k ,b k ) (1) where p(r k ,g k ,b k |t jk ) is the likelihood function of input variables given output variable, and p(r k ,g k ,b k ) is the joint probability density function. modeling using the naive bayes method consists of two assumptions; �rst, all input variables are assumed to be gaussian distributions with a probability density function as in (2) for input variable r k with parameters � rk and � rk ; second, each input variable is assumed to be distributed as the best distribution model of the gaussian distribution and gamma distribution with a probability density function as in (3) for input variable r k with parameters � rk and � rk ; based on 5 goodness of �t tests; © 2020 the authors. page 112 of 116 resti et. al. science and technology indonesia, 5 (2020) 111-116 kolmogorov-simirnov [28], cramer von mises [29], andersondarling [30], akaike information criteria and bayesian information criteria [31]. the �rst assumption is called original model (om), while the second assumption is called the best model (bm). p(r k ;� rk ,� rk ) = 1 � rk √ 2� exp [ − 1 2 ( r k − � rk � rk ) 2 ] (2) p(r k ;� rk ,� rk ) = 1 � � rk rk γ(� rk ) r � rk −1 k exp [ − ( r k � rk )] (3) 5. measuring the performance of can classi�cation for each conveyor-belt type data (�rst speed and second speed) and both model assumptions; original model (om) and model based on best distribution (bm). om assumes all input variables are gaussian distributed while bm is a model based on the best distribution of input variables. the accuracy performance is calculated as the mean of accuracy level. 3. results and discussion 3.1 the best distribution model of input variables all variables from the two data are tested with 5 goodness of �t tests to determine the suitability of each variable with the gaussian and gamma distribution models. the results of 5 goodness of �t tests for the 1st speed data are given in table 3, while the parameters of the best distribution models are given in table ?? the distribution model that has smaller goodness of �t value is a better model. each of input variable has 2 5 tests that support it as the best model. the best distribution model of the input variables r, g, and b are all gamma distributions, on the 2nd can type are all gaussian distributions, while on the 3rd cans type are gamma, gaussian, and gamma distributions, respectively. the results of the goodness of �t tests of all input variables for each can type of the second conveyor belts speed and the parameters of the best distribution models are given in table 5 and table 6 successively. table 5 informs that on the 1st can type, the best distribution model of the input variables r, g, and b are all gamma distributions, on the 2nd can type are gamma, gaussian, gamma distributions, while on the 3rd cans type are all gamma distributions. in the 2nd speed, at least each input variable has three tests that support it as the best model, and on average it has four tests that support it. 3.2 performance of classi�cation table 7 shows the accuracy level of each conveyor-belt type both in the original model (om) and the best distribution model (bm). each group has a di�erent accuracy level for each conveyorbelt type both in the original model (om) and the best distribution model (bm). to that end, classi�cation performance is measured as the mean of the accuracy levels of the 50 groups. the variances, bias and con�dence interval of the mean of the 50 groups are also presented in table 7. the mean of the classi�cation accuracy level of 50 groups noted that bm has better accuracy than om, both on the 1st data speed (the 1st conveyor-belt type) with a di�erence of 0.4%, and the 2nd data speed (the 2nd conveyor-belt type) with a di�erence of 0.1%. the variance, bias, and con�dence interval of the mean in both data also show that bm has better performance than om. this small di�erence in the four statistics can be caused by the variable distribution model adjusted for each input variable only two, namely gaussian and gamma. fitting the distribution of input variables to more distribution models allows a more appropriate distribution model to be obtained so that the level of accuracy can be higher. comparison of the measurement of accuracy of the 1st and 2nd speeds for both om and bm has a di�erence of around 6-7%, a bias di�erence of around 5-8%, and a con�dence interval of more than 7%. these measurements show that the performance of can classi�cation at the 1st speed is better than the 2nd speed at both om and bm. 4. conclusions this paper proposed the performance of a can classi�cation system based on the digital image built using 2 types of conveyor belts and 2 types of models in the naive bayes method to obtain the highest level of accuracy. the performance of the classi�cation accuracy is built by dividing data into the learning data and testing data with a composition of 50:50 in which each data is designed into 50 groups with di�erent percentages on each type of cans using resampling techniques with replacement. the results show that the classi�cation system was built using assumption the best distribution model for each input variable has a better performance of accuracy than the model that assumes all input variables are gaussian distributed, and the performance of accuracy on the �rst speed is better than the second speed, both on the original model (om) and the model based on the best (bm) distribution. overall, the best classi�cation performance is owned by the naive bayes method which assumes the best distribution model for each input variable where image data is obtained from the capturing system with a conveyor belt speed of 0.181 m/s. important notes from the results of this study are �rst, the conveyor belt speed when capturing images a�ects the pixel value of red, green, and blue and ultimately a�ects the results of the classi�cation of cans. second, not all input variables are gaussian distributed. implementation of the best statistical distribution model on the naïve bayes method can in�uence the results of classi�cation but it is necessary to test more statistical distribution models to obtain signi�cant results. 5. acknowledgement this research was supported by dipa, university of sriwijaya, no. sp dipa-042.01.2.400953/2019, for the competitive research, no. 0015 /un9/sk.lp2m.pt/2019. © 2020 the authors. page 113 of 116 resti et. al. science and technology indonesia, 5 (2020) 111-116 table 3. goodness-of-�t test for the 1st speed input goodness the 1st cans type the 2nd cans type the 3rd cans type variable of �t gaussian gamma gaussian gamma gaussian gamma r1 ks 0.12 0.12 0.07 0.06 0.06 0.06 cvm 0.20 0.17 0.06 0.07 0.04 0.04 ad 1.47 1.28 0.55 0.58 0.27 0.26 aic 599.42 595.44 404.34 405.02 619.17 618.61 bic 604.03 600.05 409.18 409.86 624.24 623.67 g1 ks 0.11 0.11 0.09 0.09 0.06 0.07 cvm 0.13 0.12 0.16 0.16 0.05 0.06 ad 1.02 0.95 1.33 1.40 0.34 0.39 aic 555.60 553.72 399.01 400.00 548.47 548.81 bic 560.21 558.33 403.84 404.84 553.54 553.87 b1 ks 0.12 0.11 0.12 0.13 0.06 0.06 cvm 0.32 0.27 0.16 0.16 0.06 0.06 ad 2.20 1.87 1.06 1.13 0.40 0.40 aic 573.56 568.51 426.78 428.04 576.68 575.79 bic 578.17 573.12 431.62 432.88 581.74 580.85 table 4. parameter of the best distribution model for the 1st speed input the 1st cans type the 2nd cans type the 3rd cans type variable parameter parameter parameter r1 �r11 144.89 �r21 150.87 �r31 565.11 �r11 0.91 �r21 12.49 �r31 3.61 g1 �g11 249.84 �g21 154.02 �g31 158.03 �g11 1.59 �g21 2.63 �g31 4.54 b1 � b11 193.40 � b21 150.84 � b31 866.93 � b11 1.27 � b21 3.11 � b31 5.62 table 5. goodness-of-�t test for the 2nd speed input goodness the 1st cans type the 2nd cans type the 3rd cans type variable of �t gaussian gamma gaussian gamma gaussian gamma r2 ks 0.13 0.12 0.07 0.07 0.11 0.11 cvm 0.32 0.26 0.09 0.09 0.25 0.22 ad 1.79 1.45 0.62 0.60 1.28 1.13 aic 603.33 598.39 460.68 460.54 627.62 625.43 bic 607.94 603.00 465.52 465.38 632.68 630.49 g2 ks 0.08 0.08 0.08 0.08 0.06 0.05 cvm 0.11 0.08 0.09 0.10 0.05 0.04 ad 0.70 0.54 0.61 0.66 0.31 0.27 aic 552.90 550.84 441.79 442.09 597.78 596.59 bic 557.51 555.45 446.62 446.93 602.85 601.65 b2 ks 0.15 0.14 0.07 0.07 0.08 0.08 cvm 0.41 0.34 0.04 0.04 0.17 0.15 ad 2.41 1.96 0.31 0.32 1.31 1.09 aic 576.11 570.59 445.38 445.40 608.33 604.17 bic 580.71 575.20 450.22 450.22 613.39 609.23 © 2020 the authors. page 114 of 116 resti et. al. science and technology indonesia, 5 (2020) 111-116 table 6. parameter of the best distribution model for the 2nd speed input the 1st cans type the 2nd cans type the 3rd cans type variable parameter parameter parameter r2 �r21 132.13 �r22 1518.32 �r23 477.43 �r21 0.85 �r22 10.29 �r23 3.19 g2 �g21 246.83 �g22 150.63 �g23 663.66 �g21 1.61 �g22 3.38 �g23 4.40 b2 �b21 180.19 �b22 147.95 �b23 585.61 � b21 1.20 � b22 3.46 � b23 3.97 table 7. performance of naive 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(1974). edf statistics for goodness of �t and some comparisons. journal of the american statistical association, 69(347); 730–737 wang, y. and q. liu (2006). comparison of akaike information criterion (aic) and bayesian information criterion (bic) in selection of stock–recruitment relationships. fisheries research, 77(2); 220–225 yani, i., m. hannan, h. basri, e. scavino, and n. e. bin ahmad basri (2009). detecting object using combination of sharpening and edge detection method. european journal of scienti�c research, 32(1); 121–127 yani, i., e. scavino, m. hannan, d. wahab, and h. basri (). an automatic sorting system for recycling beverage cans using the eigenface algorithm. in proceedings of the third international conference on soft computing technology in civil, structural and environmental engineering. civil-comp press © 2020 the authors. page 116 of 116 introduction experimental section methods results and discussion the best distribution model of input variables performance of classification conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper coefficient bound of a new generalized class of tilted analytic univalent functions abdullah yahya1*, mohd najir tokachil1, hasilatul hana hamzah2, shahriel mohd saifullah pirman3, siti asiah che muhammad4 1faculty of computer and mathematical sciences, universiti teknologi mara, seremban, 70300, malaysia 2j.k wire harness sdn. bhd. no. 7 and 9, kawasan perindustrian tebrau 1, johor bahru, 81100, malaysia 3sekolah menengah kebangsaan jambatan putih, tawau, 91019, malaysia 4power cables malaysia, purchasing department, shah alam, 40702, malaysia *corresponding author: abdullahyahya@uitm.edu.my abstract this paper is concerned with the new generalized class of tilted analytic univalent functions, s∗(θ,α,s,t) which denoted as. re{eiθ f ′(z) z m(z) } > α, for cos θ > α, |θ| < π, 0 ≤ α <1, m(z)= z (1−sz)(1−tz) , s, 1, -1 ≤ t < 1, s, t and s, t ∈ c which is analytic in the unit disk ∆={w:|w|<1}. the coefficient bound as well as representation theorem of extremal properties is obtained s∗(θ,α,s,t). keywords analytic functions, univalent functions, representation theorem, coefficient bound received: 15 september 2021, accepted: 02 january 2022 https://doi.org/10.26554/sti.2022.7.1.67-72 1. introduction let u represent the class of functions presented by f (z)= z+ a2z 2 + a3z 3 + ...+ anz n + ... (1) which are regular in ∆={w:|w|<1} and is the subclass of u consisting of normalized univalent functions which are satisfying f(0)=0 and f’(0)-1=0 (goodman, 1983; duren, 2001). we also denote the subclass of u containing functions that are starlike, convex, and close-to-convex by st, k and c respectively. silverman and silvia (1996) obtained representation theorem and coe�cient bound for the class g(δ, 0) satis�es re(eiδ f ′z h′z ) >0 |δ|< π 2 , h(z) ∈ k and z ∈ ∆. subsequently, mohamad (1998) introduced the class g (λ,γ) satis�es re(eiλ f ′z h′z ) > γ,where |λ|≤ π, cosλγ >0 and z ∈∆ which is the same h,(z) done by silverman and silvia (1996) and discovered representation theorem and coe�cient bound of g (α,δ). afterward, soh and mohamad (2006) determined extremal properties for the class of functions which h(z)= -z-2 (log(1-z)) implies n’(z)= (1+(z))(1-z)−1 where it is the extreme function produced by macgregor (1962) . next, cik soh (2009) introduced the class g (λ,γ,γ) with the form of kγ(z)= -z(1-2γ)-(log(1-z))(2-2γ) where 0≤γ≤1 g′(z)= 1+(1−2γ)z1−z and the author presented some extremal properties of g (λ,γ,γ). kaharudin (2011) has expanded the results from cik soh (2009) by presenting a special case of gβ (z) when β= 1 2 given by brickman et al. (1973) and found important properties of the coe�cient bound and the rotation theorem for this class of functions. in addition, many researchers such as macgregor (1962) , goel (1967) , macgregor (1964) , silverman (1972) , goel and mehrok (1983) , silverman and telage (1979) , fukui et al. (1987) , yahya et al. (2014) , kaplan (1952) , mohamad (2000) , akbarally et al. (2011) , wang (2010) , shashkin (1994) , çağlar et al. (2013) , magesh and yamini (2013) , elhaddad and darus (2020) , adegani et al. (2021) , and shaba and wanas (2022) had studied geometrical properties of the di�erent class of functions. in the present paper, we introduce a new generalized class of tilted analytic univalent functions s∗(θ,α,s,t) as the class of normalized functions f ∈ u ful�lling the condition re ( eiθ zf ′(z) m(z) ) > α, (z ∈∆) for cos θ > α, |θ| < π, 0 ≤ α <1, m(z)= z (1−sz)(1−tz), s, 1, -1 ≤ t < 1, s , t and s, t ∈ c. thus, our purpose in the present paper is to obtain representation theorem and coe�cient bound of s∗(θ,α,s,t)f. https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.67-72&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.67-72 yahya et. al. science and technology indonesia, 7 (2022) 67-72 2. representation theorem suppose that p is the class of all functions with a positive real part ∆={w:|w|<1}. thus, we can write the function p(z) ∈ p= p(z)= 1+ p1z+ p2z2+...+ pnzn+... as that is analytic in ∆={w : |w| < 1} such that re {p(z)}>0. next, we relate the functions s∗(θ,α,s,t) to the functions in p. for any f ∈ u, we have eiθ zf ′(z) m(z) −α − isinθ cosθ −α = p, (z, ∈,∆) (2) the approach of the herglotz representation theorem will be carried on for the establishment of the representation theorem s∗(θ,α,s,t) 2.1 theorem let f ∈ s∗(θ,α,s,t), then some probability measure µ on the unit circle x f can be shown as f (z)= ∫ x [[ log(1−xsz) x − log(1−xtz) x ] + ( 2aθαe −1θ ) [ − log(1−xz) (s−1)− (t−1)x + log(1−xsz) s (t− s)− (s−1)x − t log(1−xtz) (t− s)− (t−1)x ] ( 2αeiθ−e −2iθ (t− s) )] dµ(x) (3) and conversely, i f t is given by the (3), then f ∈ s∗(θ,α,s,t). proof. we have p ∈ p which is p(z)= ∫ x (1+xz)(1-xz)−1 dµ(x), |x|=1, for some probability measure µ on the unit circle x. rearranging yields, eiθ zf ′(z) m(z) z = p(z)(cosθ −α)+α + isinθ , and by replacing cosθ-α= aθα that is always positive, we have f ′(z)= m(z) zeiθ [aθαp(z)+α + isinθ] therefore, f ′(z)= e−iθ m(z) z [aθαp(z)+α + isinθ] (4) substituting m(z)= z (1−sz)(1−tz) into (4), we have f ′(z)= e−iθ ( z (1− sz)(1− tz) ) ( 1 z ) [aθαp(z)+α + isinθ] and f ′(z)= e−iθ ( 1 (1− sz)(1− tz) ) [aθαp(z)+α + isinθ] (5) from, we have f ′(z)= e−iθ ( 1 (1− sz)(1− tz) ) aθα ∫ x (1+xz) (1−xz) dµ(x)+α + isinθ  then, we obtain f ′(z)= ∫ x e−iθ [ (α + isinθ)(1−xz)+ (1+xz)aθα (1−xsz)(1−xtz)(1−xz) ] dµ(x) it follows that f (z)= z∫ 0 ∫ x e−iθ [ aθα(1+xϕ)+ (α + isinθ)(1−xϕ) (1−xsϕ)(1−xtϕ)(1−xϕ) ] dµ(x)dϕ and f (z)= z∫ 0 ∫ x e−iθ [ (cosθ +xϕcosθ −α −xϕα + isinθ −xϕisinθ +α −xϕα) (1−xsϕ)(1−xtϕ)(1−xϕ) ] dµ(x)dϕ then, f (z)= z∫ 0 ∫ x e−iθ [ (cosθ + isinθ)+xϕ(cosθ − isinθ)−2xϕ+α −xϕα) (1−xsϕ)(1−xtϕ)(1−xϕ) ] dµ(x)dϕ since cos a+ i sin a= eia and cos ai sin a= e−ia f (z)= z∫ 0 ∫ x [ 1+xϕ [ (e−2iθ cosθ)−2α(e−iθ) ] (1−xsϕ)(1−xtϕ)(1−xϕ) ] dµ(x)dϕ (6) upon simpli�cation (6) , we have f (z)= z∫ 0 ∫ x [ (e−iθ −2α)e−iθ +1 (1−xsϕ)(1−xtϕ)(1−xϕ) −(e−iθ −2α)e−iθ (1−xsϕ)(1−xtϕ) ] dµ(x)dϕ by changing the integration order, we obtain that f (z)= ∫ x  z∫ 0 [ (−e−2iθ +2αe−iθ) (t − s) ( − s (1−xsϕ) + t (1−xtϕ) ) +(2aθαe −iθ ) ( 1 (s−1)(t −1)(1− xϕ) − s2 (t− s)(s−1)(1−xsϕ) + t2 (t− s)(t−1)(1−xtϕ) )] dϕ ] dµ(x) (7) integrating (7) φ concerning, © 2022 the authors. page 68 of 72 yahya et. al. science and technology indonesia, 7 (2022) 67-72 f (z)= ∫ x [[ log(1−xsz) (x) − log(1−xtz) (x) ] +(2aθαe −iθ ) [ − log(1−xz) (s−1)(t−1)x + s log(1−xsz) (−s+ t)(s−1)x − t log(1−xtz) (−s+ t)(t−1)x ] ( 2αe−iθ − e−2iθ (−s+ t) )] dµ(x) which |x|= 1, and this is desired representation. 2.2 corollary the extreme points s∗(θ, α, s, t) are the unit points masses fx(z)= ∫ x [[ log(1−xsz) (x) − log(1−xtz) (x) ] + (2aθαe −iθ ) [ − log(1−xz) (−1+ s)(−1+ t)x + s log(1−xsz) (−s+ t)(−1+ s)x − t log(1−xtz) (−s+ t)(−1+ t)x ] ( 2αe−iθ − e−2iθ (−s+ t) )] , with |x|=1. meanwhile, f ′x (z)= (−e−2iθ +2αe−iθ) (t − s) ( − s (1−xsz) + t (1−xtz) ) + (2aθαe −iθ ) ( 1 (−1+ s)(−1+ t)(1− xz) − s2 (−s+ t)(−1+ s)(1−xsz) + t2 (−s+ t)(−1+ t)(1−xtz) ) , is the derivatives of the extreme points for s∗(θ, α, s, t) with |(x)|=1. thus f is normalized functions since f (0)= ∫ x [[ log(1−xs(0)) (x) − log(1−xt(0)) (x) ] + (2aθαe −iθ ) [ − log(1−x(0)) (−1+ s)(−1+ t)x + s log(1−xs(0)) (−s+ t)(−1+ s)x − t log(1−xt(0)) (−s+ t)(−1+ t)x ] ( 2αe−iθ − e−2iθ (−s+ t) )] = 0 and f ′(0)= (−e−2iθ + (2α)e−iθ) (−s+ t) ( t (1−xt(0)) − s (1−xs(0)) ) + (2aθαe −iθ ) ( 1 (s−1)(t −1)(1− x(0)) − s2 (t− s)(s−1)(1−xs(0)) + t2 (t− s)(t−1)(1−xt(0)) ) = 1 3. main result now, we proceed on �nding coe�cient bound of s∗(θ, α, s, t)f. 3.1 theorem if f � s∗(θ, α, s, t), then |an | 5 s.sn + aθα(2sn −4s.sn) n(−s+ t)(−s+1) + aθα(2tn −4t.tn)− tn + t.tn n(−s+1)(−1+ t) + 2aθα n(−1+ s)(−1+ t) for n=2,3,4,...and equality is attained for each n when f is an extreme point of s∗(θ, α, s, t). proof. from (7), we have f (z)= z∫ 0  ∫ x [ − (−e−2iθ + e−iθ(2α))s (t − s)(1− xsϕ) − (e−iθ(2aθα))s 2 (t − s)(s−1)(1− xsϕ) + (−e−iθ + (2α))te−iθ (−s+ t)(1− xtϕ) − e−iθ(2aθα)t 2 (−s+ t)(−1+ t)(1− xtϕ) + 2e−iθ(aθα) (−1+ s)(−1+ t)(1− xϕ) ] dµ(x) ] dϕ and f (z)= z∫ 0  ∫ x [( − (−e−2iθ + e−iθ(2α))s (−s+ t) − (e−iθ(2aθα))s 2 (−s + t)(−1+ s) ) 1 (1− xsϕ) + ( (e−iθ(−e1θ +2α)t (−s+ t)(1− xtϕ) − e−iθ(2aθα)t 2 (−s+ t)(−1+ t) ) 1 (1− xtϕ) + ( e−iθ(2aθα) (−1+ s)(−1+ t) ) 1 (1− xϕ) ] dµ(x) ] dϕ (8) next, (8) be written as f (z)= z∫ 0 [( − (−e−2iθ +2αe−iθ)s (−s+ t) − (2aθαe −iθ)s2 (−s + t)(−1+ s) ) ∫ x ∞∑ 0 [ (sx)n ] dµ(x)(ϕ)n + ( (−e−2iθ +2αe−iθ)t (−s + t) − (2aθαe −iθ)t2 (−s+ t)(−1+ t) ) ∫ x ∞∑ 0 [ (tx)n ] dµ(x)(ϕ)n + ( (2aθαe −iθ) (−1+ s)(−1+ t) ) ∫ x ∞∑ 0 [ xndµ ] (x)(ϕ)n  dϕ (9) from (9), substituting n=0, then © 2022 the authors. page 69 of 72 yahya et. al. science and technology indonesia, 7 (2022) 67-72 f (z)=− (−e−iθ +2α)e−iθ(−1+ s)(−1+ t)s (−s+ t)(−1+ s)(−1+ t) − e−iθ(2aθα)(−1+ t)s2 (−s+ t)(−1+ s)(−1+ t) + (−e−2iθ +2αe−iθ)(−1+ s)(−1+ t)t (−s+ t)(−1+ s)(−1+ t) − (2aθαe−iθ)(−1+ s)t2 (−s+ t)(−1+ s)(−1+ s) + (2aθαe−iθ)(−s+ t) (−s+ t)(−1+ s)(−1+ t) and f (z)= 1 (t − s)(s−1)(t −1) (e−2iθs2t −2αs2t −(e−2iθ)s2 − e−2iθ(st)+ (2αs2)e−iθ + (2αst)e−iθ −2αse−iθ + se−2iθ)− (2s2t −2s2)aθαe −iθ + (st2(−e−2iθ) +2αe−iθst2 + e−2iθst + e−2iθt2 − e−iθ(2αst) − e−iθ(2αt2)− e−2iθt + e−iθ(2αt)+ (2st2 −2t2) aθαe −iθ + (2t −2s)aθαe −iθ ) (10) upon simpli�cation the equation (10), we have f (z)= 1 (t − s)(s−1)(t −1) [ (s2t − s2 + s− st2 + t2 − t)e−2iθ +(−2s2t −2s+2s2 +2st2 −2t2 +2t)αe−iθ +(−2s2t −2s+2s2 +2st2 −2t2 +2t)αe−iθ +(−2s2t +2s2 +2st2 +2t −2t2 −2s)aθαe −iθ ] substituting aθα= cosθ-α and cosθ= eiθ−e−iθ 2 , thus f (z)= 1 (t − s)(s−1)(t −1) [ (s2t − s2 + s− st2 + t2 − t)e−2iθ +(−2s2t +2s2 −2s+2st2 −2t2 +2t)αe−iθ +(−2s2t +2s2 +2st2 −2t2 +2t −2s)( 1+2e−iθ −2αe−iθ 2 )] and f (z)= 1 (t − s)(s−1)(t −1) + [ (−2s2t +2s2 −2s+2st2 −2t2 +2t)αe−iθ + (−s2t + s2 − s+ st2 − t2 + t)e−2iθ +(2s2t −2s2 +2s−2st2 +2t2 −2t)+ (−s2t + s2 −s+ st2 − t2 + t) ] = 1 (−s+ t)(s−1)(t −1) [(−s+ t)(s−1)(t −1)] = 1 rewrite the equation (9) will yield to f (z)= w∫ 0 [ 1− ( (−e−2iθ +2αe−iθ)s (t − s) − (2aθαe−iθ)s2 (t − s)(s−1) ) ∫ x ∞∑ 0 [(sx)n]dµ(x)(ϕ)n + ( (−e−2iθ +2αe−iθ)t (t − s) − (2aθαe−iθ)t2 (t − s)(t −1) ) ∫ x ∞∑ 0 [(tx)n]dµ(x)(ϕ)n + ( (2aθαe−iθ) (s−1)(t −1) ) ∫ x ∞∑ 0 [xndµ] (x)(ϕ)n  dϕ integrating φ concerning gives us, f (z)=z− ( (−e−2iθ +2αe−iθ)s (t − s) − (2aθαe−iθ)s2 (t − s)(s−1) ) ∫ x ∞∑ 2 [ (sx)n−1 n ] dµ(x)zn + ( (−e−2iθ +2αe−iθ)t (t − s) − (2aθαe−iθ)t2 (t − s)(t −1) ) ∫ x ∞∑ 2 [ (tx)n−1 n ] dµ(x)zn + ( (2aθαe−iθ) (s−1)(t −1) ) ∫ x ∞∑ 2 [ (x)n−1 n ] dµ(x)zn as a comparison above equation (1) , we have an =− ( e−iθ(−e−iθ +2α)s (−s+ t)n − e−iθ(2aθα)s2 (−s+ t)(s−1)n ) ∫ x (sx)n nsx dµ(x)+ ( e−iθ(−e−iθ +2α)t (−s+ t)n − e−iθ(2aθα)t2 (−s+ t)(t −1)n ) ∫ x (tx)n−1dµ(x)+ ( e−iθ(2aθα) n(s−1)(t −1) ) ∫ x (x)n nx dµ(x) and |an | = ����[− (e−iθ(−e−iθ +2α)s(−s+ t)n − e−iθ(2aθα)s2(−s+ t)(s−1)n ) (s)n−1 + ( e−iθ(−e−iθ +2α)t (−s+ t)n − e−iθ(2aθα)t2 (−s+ t)(t −1)n ) (t)n−1 + ( e−iθ(2aθα) n(s−1)(t −1) )]  ∫ x (x)n−1dµ(x)  ������ . upon simpli�cation −e−2iθ + 2αe−iθ = 1-2 aθαe−iθ , we have © 2022 the authors. page 70 of 72 yahya et. al. science and technology indonesia, 7 (2022) 67-72 |an | = 1 n ������  ∫ x (x)n−1dµ(x)  [( (2aθα)s 2e−iθ (−s+ t)(s−1) − (1− [ eiθ ] 2aθα)s (−s+ t) ) (s)n−1 + ( (1−2e−iθaθα)t (−s+ t) − e−iθ(2aθα)t 2 (−s+ t)(t −1) ) (t)n−1 + ( e−iθ(2aθα) (s−1)(t −1) )]���� . and |an | = 1 n ������  ∫ x (x)n−1dµ(x)  [ − ( s.sn −4aθαs.sne−iθ − sn +2snaθαe−iθ (−s + t)(−1+ s) ) + ( t.tn −4aθαt.tne−iθ − tn +2tnaθαe−iθ (−s+ t)(−1+ t) ) + ( 2aθαe−iθ (−1+ s)(−1+ t) )]���� then, since |e−iθ |=1, |an | = 1 n ������  ∫ x (x)n−1dµ(x)  [ − ( s.sn − sn + (2sn −4s.sn)aθαe −iθ (−s+ t)(−1+ s) ) + ( t.tn − tn + (2tn −4t.tn)aθαe −iθ (−s+ t)(−1+ s) ) + ( 2aθαe −iθ (−s+ t)(−1+ s) )]���� ≤ 1n ∫ x |(x)n−1|dµ(x) [ s.sn − sn + (2sn −4s.sn)aθα (−s+ t)(−1+ s) + t.tn − tn + (2tn −4t.tn)aθα (−s + t)(−1+ s) + 2aθα (−s+ t)(−1+ s) ] = sn+1 − sn + (2sn −4sn+1)aθα (−s+ t)(−1+ s)n + tn+1 − tn + (2tn −4tn+1)aθα (−s+ t)(−1+ s)n + 2aθα (−s+ t)(−1+ s)n as required. equality is attained for n=2,3,4,...when 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theresa, santa oktavia ginting ...........................................................................................37 pillarization of double layer hydroxides using h [-pw o ]nh o: effect of3 12 40 2 pillarization time doi: https://doi.org/10.26554/sti.2017.2.2.45-49 muhammad imron, muhammad said ..............................................................................................45 synthesis and characterization of metal oxides supported keggin type polyoxometalate rb k [-h siv w o ]nh o2 2 2 2 10 40 2 doi: https://doi.org/10.26554/sti.2017.2.2.50-55 eiffel ostan jeski gultom, aldes lesbani..........................................................................................50 preparation, characterization, and thermal stability of b o -zro 2 3 2 doi: https://doi.org/10.26554/sti.2017.2.2.56-58 theresia debora simbolon, risfidian mohadi ....................................................................................56 front matter http://sciencetechindonesia.com https://doi.org/10.26554/sti.2017.2.2.29-36 https://doi.org/10.26554/sti.2017.2.2.37-44 https://doi.org/10.26554/sti.2017.2.2.45-49 https://doi.org/10.26554/sti.2017.2.2.50-55 https://doi.org/10.26554/sti.2017.2.2.56-58 ogy indonesia ence sci technol & p-issn: 2580-4405 e-issn: 2580-4391 science & technology indonesia science & technology indonesia is an international peer-review journal in the field of science and technology published by arts publishing in collaboration with the indonesian science and technology society (perhimpunan biologi indonesia and department of chemistry sriwijaya university). editor in chief aldes lesbani managing editor muhammad said risfidian mohadi associate editor rino r mukti hendrik oktendy lintang mohammad basyuni it support tarmizi taher address editorial office/publisher jl.seruni rt 3 bukit besar, palembang 30139-indonesia prof. aldes lesbani integrated research laboratory graduate school, sriwijaya university publication schedule science and technology indonesia publish quarterly (january, april, july, october) manuscript submission manuscript should be written in ms word format. figure, illustration, scheme, and table included in manuscript file. send the manuscript via web portal or email to admin@sciencetechindonesia.com front matter http://sciencetechindonesia.com page 1 page 2 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 3, july 2019 research paper removal of anionic direct dye using zn/al, zn/fe and zn/cr layered double hydroxides toward interlayer distance neza rahayu palapa1, tarmizi taher2, risfidian mohadi1,2, aldes lesbani1,2* 1magister of chemistry, faculty of mathematics and natural sciences, sriwijaya university, jl.. padang selasa bukit besar palembang 30139 2department of enviromental science, graduate school, sriwijaya university, jl. padang selasa no. 524 ilir barat 1, palembang-south sumatra, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstract in order to minimize harmful e�ect of synthetic dye (direct yellow and direct violet) the capacity of zn/al, zn/cr and zn/fe layered double hydroxides of these contaminant was studied in this work. batch adsorption experiment was conduct to investigate the e�ect of various operating parameters such as contact time, initial dye concentration and adsorption temperature in order to provide optimal condition in removal synthetic dye. based on result, the sorption of direct dye onto ldhs followed pseudo-second-order rate model. the equilibrium adsorption data for both direct dye was fi�ed freundlich isotherm model. keywords adsorption, synthetic dye, layered double hydroxide, kinetic, thermodynamic received: 21 june 2019, accepted: 18 july 2019 https://doi.org/10.26554/sti.2019.4.3.70-76 1. introduction water is the most important for all living organism, development and also the environment (gu et al., 2018). unfortunately, now days water source has been containing many pollutants (faust and aly, 2018). its caused by many industries doesn’t care about waste, they throwing away their waste in water irrigation, a small river and also in pond retention (faust and aly, 2018). that’s why water treatment become a serious problem environment and also many researchers are search the e�ective ways to get clean water (guimares et al., 2019; boubakri et al., 2018; palapa et al., 2018). however, rapidly demand new and diverse products based on technology in�uences many industries more prepared to using synthetic chemicals (ke�f et al., 2019), which is increasing the pollutant and harmful to human and environment (oladipo et al., 2019). nowadays, almost 78% of industries such as textile, paper, leather, paints, food and also cosmetics are using synthetic dyes (faust and aly, 2018; marzbali et al., 2017). in the large scale, synthetic dye continuously causing environmental water gets worse (taher et al., 2019b). indeed the presence of these substances in the aquatic environment reduces the oxygen and disturbs the biological cycle of aquatic biota (taher et al., 2019b; ke�f et al., 2019). moreover, the presence of a pollutant in drinking water is more dangerous to human, its can caused reproductive system disorder, caused cancer liver, brain, mutagenic and carcinogenic (palapa et al., 2018; saria et al., 2018; faust and aly, 2018). generally, many textile industries used direct dye, due to their excellent binding ability (boubakri et al., 2018). removal the pollutant into wastewater has been studied taking the e�ciency and cost, various methods such as biological treatment (faust and aly, 2018), membrane �ltration (xiao et al., 2019), electrochemical, photochemical (zhu et al., 2018), coagulation (huang et al., 2019), degradation and adsorption (taher et al., 2019a). most of them have high cost and not easy to operation, except, adsorption. the adsorption process has widely used, easy to operation, low cost and high e�ectiveness water treatment. in fact, the main weakness of the adsorption method is the high cost and impurity of the conventional sorbent. hence, cheaper and e�ective sorbent is still required to solve this problem (miandad et al., 2018). now, researchers have been focused on the development of natural clays. layered double hydroxides are the one of synthetic clay mineral which has ability to removal various contaminant from aqueous solution. layered double hydroxides (ldhs) has consist of brucite layers by metal cation divalent and trivalent substituted (palapa et al., 2019). generally, ldhs has formula [m2+(1x)m3+x(oh)2](an-)x/nh2o, (denoted as m 2+ and m3+ , where m2+ is a divalent metal cation, such as mg2+, fe2+, co2+, cu2+, ni2+, ca2+, and m3+ is a trivalent metal cation, such as al3+, cr3+, ga3+, mn3+ or fe3+. ldhs has unique structure properties favorable for adsorption of dye, which is they have speci�c features like no toxic, anion exchange properties, good thermal stability, has high �exibility, high surface area, and easy to hanhttps://doi.org/10.26554/sti.2019.4.3.70-76 palapa et. al. science and technology indonesia, 4 (2019) 70-76 figure 1. xrd pattern of zn/al, zn/cr and zn/fe ldhs figure 2. ftir spectra of zn/al, zn/cr and zn/fe ldhs dling (taher et al., 2019a; palapa et al., 2019; boubakri et al., 2018; nidheesh et al., 2018; tajuddin et al., 2018). in this work, ldhs was made to study of removal ability direct dye onto ldhs from aqueous solution. ldhs has been prepared by co-precipitation method and characterized using xrd, ftir and surface area analyses by bet method. the adsorption factors performance such as time, initial dye concentration and temperature was investigated. sorption capacity was studied using kinetic laws and isotherm models. 2. experimental section 2.1 materials the chemical used in this experiment are analytical grade, such as zinc nitrate, aluminum nitrate, iron nitrate, chromium nitrate and also sodium nitrate was purchased by merck, dyes were obtained in local textile industry in palembang and the water was used as solvent was obtained by purifying water de-ionized figure 3. isotherm graphic adsorption-desorption of (a) zn/al, (b) zn/cr and (c) zn/fe ldhs ‘purite’. ldh was characterized using a rigaku mini�ex 600, shimadzu prestige-21 and bet (asap micromeritics 2020). 2.2 methods 2.2.1 synthesis of layered double hydroxide according to palapa et al. (2019), the synthesis of layered double hydroxide was conducted to alkaline precipitation with divalent and trivalent metal cation ratio 3:1 at nitrogen atmosphere. prepare the alkaline solution for zinc nitrate (0.75 m), aluminum nitrate (0.25 m), chromium nitrate (0.25 m) and also iron nitrate (0.25 m). divalent and trivalent metal cation are mixed as long as an hour and added to 50 ml of sodium hydroxide (2 m) with continuous stirring 240 rpm for 4 hours at 60 ºc. then the solution was adjusted at ph 10 using sodium hydroxide and let the mixing solution at 60 ºc overnight. after that, the solution kept in oven at 80 ºc until we obtain gel, then ldh was �ltered, washed for several times using de-ionized water and �nally dried at 60 ºc for 24 h. the obtained solid then keep in a sealed bottle and ready for further used as an adsorbent. 2.2.2 adsorption experiment as much as 0.05 g of adsorbent was added to 50 ml of dyes solution in a certain concentration, in this work we used direct yellow and direct violet dye as the adsorbate. the dye solution was prepared by 1 g of each dye were diluted into 1000 ml (as stock solution) then dissolve gradually. then 0.05 g adsorbent added into 50 ml adsorbate and shaken with speci�ed time at 240 rpm. after that, the solution was �ltered and the �nal concentration was calculated using uv-vis spectrophotometer. 3. results and discussion 3.1 adsorbent characterization zn/al, zn/cr and zn/fe layered double hydroxides (ldhs) were successfully prepared and each ldhs were characterized by xrd, ft-ir and surface area analyses. the result of x-ray di�raction was shown in fig. 1. the pattern was shown the unique di�raction of ldhs amount 10º, 22º, 30º, 35º, 49º and overlapping peaks at 60º are characterized by ldhs. for all ldhs, the sharp peaks at amount 10o were indicated interlayer of ldhs with higher distance is zn/al 7.57 å, zn/cr 7.32 å and zn/fe 5.80 å. then all of ldhs has been characterized using ftir and the spectra were shown in fig 2. zn/al, zn/cr and zn/fe spectra have identically vibration were indicating nitrate band, oh band and m-o band. all identical spectra were shown in fig © 2019 the authors. page 71 of 76 palapa et. al. science and technology indonesia, 4 (2019) 70-76 figure 4. e�ect of contact time adsorption (a) direct yellow and (b) direct violet onto layered double hydroxides (ldhs) figure 5. e�ect of initial concentration of (a) direct yellow dye and (b) direct violet dye onto ldhs at various temperature 2. amount 3400-3600 cm−1 for oh band, a vibration of nitrate anions at 1380 cm−1 and vibration under 1000 cm−1 generally indicate m-o band. according to boubakri et al. (2018); taher et al. (2019a), layered double hydroxides has much potential application its because layered double hydroxides have unique structure as layer materials which is interlayer easily to exchangeable. so, in this work, ldhs were characterized by surface area analyses by bet method. the result of each ldhs shows in fig 3 and table 1. fig. 3 were shows the curve of adsorption and desorption of zn/al, zn/cr and zn/fe ldh, respectively. the typical nitrogen adsorption-desorption isotherms and the corresponding pore size distribution and the fig. 3 indicating zn/al, zn/cr and zn/fe ldhs have mesoporous pore. table 1. listed the volume pore and pore size based on digital data of characterization. according to iupac, diameter pore of material such as micropore has pore <2 nm, mesopore between 2-50 nm and macropore >50 nm. table 1. data of volume pore and pore size of layered double hydroxides adsorbent sbet volume pore pore size (m2/g) (bjh, cm3 /g) (�, nm) zn-al-no3 9.4128 0.045351 19.2743 zn-fe-no3 2.8834 0.010334 14.6964 zn-cr-no3 11.865 0.112128 3.77051 3.2 adsorption study 3.2.1 kinetic adsorption study e�ect of adsorption time of direct dyes by zn/al, zn/cr and zn/fe ldhs was shown in fig. 4. the adsorption process of direct dye onto layered double hydroxides was setting up at room temperature and 100 mg/l adsorbate for each ldhs. the result of adsorption was calculated using uv-vis spectrophotometer is the �nal concentration at 403 nm and 549 nm. after that, we calculated the % adsorbed, then we identify the kinetic parameters adsorption process. the maximum adsorption time direct yellow onto zn/al, zn/cr and zn/fe ldhs at an hour with % adsorbed are amount 83%, 81% and 38%, respectively. however the adsorption direct violet onto zn/al, zn/cr and zn/fe ldhs have maximum adsorption time at an hour amount 71%, 49% and also 27%, respectively. based on result, layered double hydroxides more e�ective to adsorb direct yellow dye than direct violet dye. in this work, we �tted two kinetic models. i.e. pseudo-�rst-order and pseudo-second-order. these kinetic models equation as follows: pseudo-�rst-order: log(qe − qt) = logqe − k1/(2.303)t (1) and pseudo-second-order: t/qt = (1/k2qe2) + (1/qe)t (2) where qe and qt are capacities of adsorbed (mg.g−1), t is time adsorption process, k1is the rate constant of the �rst order and k2 the rate constant of second-order. table 2. shows the data of kinetic parameters of direct dyes adsorption onto ldhs. based on coe�cient correlation of direct dye adsorption onto layered double hydroxides was followed pseudo-second-order kinetic model. generally, the adsorption of dye onto ldhs is quite rapidly initially until the equilibrium was reached and the value of adsorbed are constant. its caused, active site of layered double hydroxides at equilibrium are full than before reached equilibrium which is the surface active site is more available. 3.2.2 isotherm and thermodynamic study the thermodynamic was studied by varying initial concentration and temperature. in figure 5, dye adsorbed is higher at temperature 343 k so that the interaction of adsorbate and adsorbent are higher than solvent-adsorbent at active site adsorption. therefore, the adsorption for both direct dye onto ldhs at varying temperature were shown in fig. 5. fig 5 were shows the e�ect of initial concentration at various temperature. the higher adsorption capacity of both dyes (direct yellow and direct violet) is zn/al layered double hydroxides at 323 k it’s amount 98 mg/g and 36 mg/g, respectively. the isotherms models langmuir and freundlich are used for this data. the langmuir assumed that adsorbate was occupied into monolayer. its used equation as follows: ce/qe = 1/(klqmax) + (1/qmax)ce (3) © 2019 the authors. page 72 of 76 palapa et. al. science and technology indonesia, 4 (2019) 70-76 table 2. pseudo-�rst-order and pseudo-second-order sorption rate constant kinetic models. kinetic models dye parameters layered double hydroxides zn-al-no3 zn-cr-no3 zn-fe-no3 pseudo-�rst-order direct yellow k1 0.0597 0.0493 0.0339 r2 0.9127 0.873 0.891 pseudo-second-order k2 0.0064 0.005 0.0072 r2 0.9544 0.9077 0.9176 qe exp 80.791 84.565 54.965 pseudo-�rst-order direct violet k1 0.0414 0.0364 0.0339 r2 0.938 0.922 0.912 pseudo-second-order k2 0.004 0.0045 0.0072 r2 0.9297 0.9883 0.948 qe exp 75.791 62.012 44.056 table 3. langmuir and freundlich isotherm model fitted for adsorption direct yellow onto ldhs adsorbent isoterm parameters t (k) 303 313 323 zn/al langmuir qmax (mg.g-1) 100.706 118.7815 121.3768 kl (lmg−1) 0.009 0.0328 0.0515 r2 0.6023 0.7954 0.905 freundlich kf (mg.g−1)(lmg−1)1/n 3.5136 13.506 19.5108 n 1.3646 2.3814 2.6625 r2 0.9025 0.9045 0.9363 zn/cr langmuir qmax (mg.g-1) 86.4756 91.1563 104.3262 kl (lmg−1) 0.0052 0.0041 0.0033 r2 0.6999 0.992 0.9855 freundlich kf (mg.g−1)(lmg−1)1/n 1.8634 1.788 1.8525 n 1.2733 1.183 1.133 r2 0.9734 0.998 0.9986 zn/fe langmuir qmax (mg.g−1) 39.654 39.2063 32.8447 kl (lmg−1) 0.034 0.0228 0.0443 r2 0.6075 0.89 0.9793 freundlich kf (mg.g−1)(lmg−1)1/n 0.1918 1.7759 2.4524 n 0.7738 1.5642 1.6492 r2 0.9699 0.9081 0.9848 © 2019 the authors. page 73 of 76 palapa et. al. science and technology indonesia, 4 (2019) 70-76 table 4. langmuir and freundlich isotherm model fitted for adsorption direct violet onto ldhs adsorbent isoterm parameters t (k) 303 313 323 zn/al langmuir qmax (mg.g−1) 39.654 45.2025 66.093 kl (lmg−1) 0.1472 0.1246 0.0387 r2 0.9808 0.9473 0.998 freundlich kf (mg.g−1)(lmg−1)1/n 20.5059 20.6027 9.1501 n 7.4144 6.189 2.5095 r2 0.9902 0.9942 0.998 zn/cr langmuir qmax (mg.g−1) 37.6209 56.7362 47.5136 kl (lmg−1) 0.0122 0.0099 0.0239 r2 0.9202 0.7694 0.9839 freundlich kf (mg.g−1)(lmg−1)1/n 1.6529 1.5044 4.6399 n 1.8141 1.544 2.2851 r2 0.9621 0.902 0.987 zn/fe langmuir qmax (mg.g-1) 23.709 28.332 31.095 kl (lmg−1) 0.0071 0.0046 0.0409 r2 0.847 0.713 0.829 freundlich kf (mg.g−1)(lmgg−1)1/n 2.604 6.882 9.571 n 1.303 1.265 2.507 r2 0.992 0.949 0.906 table 5. values of thermodynamic parameters for the adsorption of direct yellow by ldhs t c zn/al ldh zn/cr ldh zn/fe ldh (k) (mg/l) δg δs δh δg δs δh δg δs δh (kj/mol) (j/mol.k) (kj/mol) (kj/mol) (j/mol.k) (kj/mol) (kj/mol) (j/mol.k) (kj/mol) 303 60 -1.049 64.961 18.634 -2.975 39,00 9,819 -0,989 32,01 8,71 313 -2.348 -5.714 -1,282 323 -3.647 -0.009 -1,575 303 70 -0.199 45.216 13.501 -2.18 39,75 5,223 -0,990 26,47 4,50 313 -1.104 -4.351 -1,631 323 -2.008 -0.227 -2,271 303 80 -0.245 46.498 13.844 -2.975 35,59 9,650 -1,355 17,879 7,35 313 -1.175 -5.714 -1,742 323 -2.105 -0.009 -2,129 303 90 -0.378 30.336 8.814 -2.18 47,50 9,311 -0,838 11,06 1,96 313 -0.984 -4.351 -1,379 323 -1.591 -0.227 -1,920 303 100 -0.831 28.635 7.093 -0.009 33,402 6.991 -0.012 12.3543 3.889 313 -2.075 -2.18 -1.05 323 -3.318 -4.351 -2.087 © 2019 the authors. page 74 of 76 palapa et. al. science and technology indonesia, 4 (2019) 70-76 table 6. values of thermodynamic parameters for the adsorption of direct violet by ldhs t c zn/al ldh zn/cr ldh zn/fe ldh (k) (mg/l) δg δs δh δg δs δh δg δs δh (kj/mol) (j/mol.k) (kj/mol) (kj/mol) (j/mol.k) (kj/mol) (kj/mol) (j/mol.k) (kj/mol) 303 60 -1.049 64.961 18.634 -2.975 39,00 9,819 -0,989 32.01 8.71 313 -2.348 -5.714 -1,282 323 -3.647 -0.009 -1,575 303 70 -0.199 45.216 13.501 -2.18 39,75 5,223 -0,990 26.47 4.5 313 -1.104 -4.351 -1,631 323 -2.008 -0.227 -2,271 303 80 -0.245 46.498 13.844 -2.975 35,59 9,650 -1,355 18 7.35 313 -1.175 -5.714 -1,742 323 -2.105 -0.009 -2,129 303 90 -0.378 30.336 8.814 -2.18 47,50 9,311 -0,838 11.06 1.96 313 -0.984 -4.351 -1,379 323 -1.591 -0.227 -1,920 303 100 -0.831 28.635 7.093 -0.009 33,402 6.991 -0.012 12.3543 3.889 313 -2.075 -2.18 -1.05 323 -3.318 -4.351 -2.087 where qe is the equilibrium adsorption, ce is equilibrium concentration, qmax is the maximum adsorption and kl is the equilibrium adsorption constant. then, the essential features of langmuir isotherm namely rl (equilibrium parameters). value rl has indicated the models of isotherm. if irreversible, the rl calculated zero (rl = 0), liniear when rl = 1, and favorable when 0> rl>1. the freundlich isotherm model identi�ed the heterogenous adsorbent surface. the equation is following: logqe = logkf + nlogce (4) where kf is adsorption capacity when equilibrium, the value of n gives information of favorability of adsorption process, if n=1 linear, n<1 is chemisorption and n>1 is favorable. the isotherm data were shown in table 3. tabel 3 was shown the parameters of freundlich and langmuir. the result was shows freundlich model is more �tted of the experimental data based on coe�cient correlation. this result indicated the adsorbate interact physisorption each other on surface site active of layered double hydroxides. thermodynamic study parameter was calculated and obtained enthalpy, entrophy and free gibbs energy. the value of enthalphy and entrophy shows that the adsorption process is endothermic. negative free energy value was indicated that the process is spontaneous and the desreases of free energy value with the increases of temperature indicated that the adsorption more favorable at low temperature (room temperature). 4. conclusions in this work, zn/al, zn/cr and zn/fe has been used as adsorbent for removal dyes in aqueous solution. based on result, zn/al ldhs has higher adsorption capacity than zn/cr and zn/fe ldhs. for removal direct dyes, ldhs more e�ective adsorb direct yellow dye than direct violet dye. kinetics study showed that the adsorption process is more �ts with pso than pfo based correlation coe�cients. the adsorption process is described by freundlich isotherm models for all dyes. the value of enthalpy and entropy shows that the adsorption process is endothermic and negative free energy value was indicated that the process is spontaneous. 5. acknowledgement author thankful to hibah tesis magister form ministry of research technology and higher education contract no.096/sp2h /lt/drpm/2019 references boubakri, s., m. a. djebbi, z. 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xu, y. bao, l. fan, w. kang, f. dai, r. wang, l. wang, s. hu, d. sun, and h.-c. zhou (2019). controlled hydrolysis of metal organic frameworks: hierarchical ni/co-layered double hydroxide microspheres for high-performance supercapacitors. acs nano, 13(6); 7024– 7030 zhu, y., r. zhu, g. zhu, m. wang, y. chen, j. zhu, y. xi, and h. he (2018). plasmonic ag coated zn/tildh with excellent photocatalytic activity. applied surface science, 433; 458–467 © 2019 the authors. page 76 of 76 introduction experimental section materials methods synthesis of layered double hydroxide adsorption experiment results and discussion adsorbent characterization adsorption study kinetic adsorption study isotherm and thermodynamic study conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper handling missing data using combination of deletion technique, mean, mode and artificial neural network imputation for heart disease dataset anita desiani1*, novi rustiana dewi1, annisa nur fauza1, naufal rachmatullah2, muhammad arhami3, muhammad nawawi4 1mathematics department, mathematics and natural science faculty, sriwijaya university, palembang, 30862, indonesia2informatics technique department, informatics faculty, sriwijaya university, palembang, 30862, indonesia3informatics technique department, lhokseumawe state polytechnic, aceh, 24301, indonesia4mechanical engineering departement, graduate school of science, engineering and technology, istanbul technical university maslak sarıyer, 34467, turkey *corresponding author: anita_desiani@unsri.ac.id abstracttheuniversityofcalifornia irvineheartdiseasedatasethadmissingdataonseveralattributes. themissingdatacanlossthe importantinformation of the attributes, but it cannot be deleted immediately on dataset. to handle missing data, there are several waysincluding deletion, imputation by mean, mode, or with prediction methods. in this study, the missing data were handled by deletiontechnique if the attribute had more than 70% missing data. otherwise, it were handled by mean and mode method to impute missingdata that had missing data less or equal 1%. the artificial neural network was used to handle the attribute that had missing data morethan 1%. the results of the techniques and methods used to handle missing data were measured based on the performance resultsof the classification method on data that has been handled the problem of missing data. in this study the classification method usedis artificial neural network, naïve bayes, support vector machine, and k-nearest neighbor. the performance results of classificationmethods without handling missing data were compared with the performance results of classification methods after imputationmissing data on dataset for accuracy, sensitivity, specificity and roc. in addition, the comparison of the mean squared error resultswas also used to see how close the predicted label in the classification was to the original label. the lowest mean squared error wasobtained by artificial neural network, which means that the artificial neural network worked very well on dataset that has beenhandled missing data compared to other methods. the result of accuracy, specificity, sensitivity in each classification method showedthat imputation missing data could increase the performance of classification, especially for the artificial neural network method. keywordsmissing data, artificial neural network, imputation, mean-mode, deletion, heart disease received: 10 june 2021, accepted: 18 september 2021 https://doi.org/10.26554/sti.2021.6.4.303-312 1. introduction theheartdiseasedataset isoftenused inclassicationorprediction. that is used to determine the pattern of factors that aect a heart disease. heart disease is one of the biggest causes of death in the world (rahakbauwet al., 2016). based on research that has been conducted by stewart et al. (2017), nearly one billion people worldwide suer strokes caused by hypertension and heart attacks. some data on the results of examining heart disease diagnoses are published as a dataset to help various researches. one data warehouse that provides a heart attack dataset is the university of california irvine (uci) machine learning repository. the heart attack dataset provided by the uci is heart disease diagnostic data collected based on four sources, namely the cleveland clinic foundation (cleveland data), hungarian institute of cardiology, budapest (hungarian data), va medical center, long beach, ca (long-beach-va data), and university hospital, zurich, switzerland (switzerland data). data from these various sources was published by uci into a dataset of diagnoses of heart disease patients which can be used for prediction of heart disease patients (jasoni and steinbrunn, 2013). the heart disease patient dataset contains 76 attributes, but only 14 attributes that aect heart disease (zriqat et al., 2016). the heart attack dataset has incomplete data about 491 missing data from several attributes (misir and samanta., 2017). although it has weaknesses in the completeness of the data and attributes used, the heart attack dataset has been widely used in various studies to diagnose patients with heart disease. missing data problems can occur in various datasets not only in uci heart disease dataset, such as gene and microarray data (moorthy et al., 2014), medical data (karim et al., 2017; https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.303-312&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.303-312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 purwar and singh, 2015), credit data (crone and finlay, 2012; lan et al., 2020), software quality dataset (huang et al., 2017; jing et al., 2016), etc. the missing data problems are a common problem in real-world data classication. therefore, a strong classication method is needed when classifying data that has missing data problems in its dataset domain (somasundaram and nedunchezhian, 2012). missing data is caused by several things including errors in manual data entry procedures, equipment errors or wrong measurements (purwar and singh, 2015). incomplete dataset will aect the accuracyof the data mining model, it can give biased results, and reduce the eciency of the computation process because there is missing information in the dataset (choudhury and pal, 2019). the missing data can signicantly reduce the accuracy and usefulness of the assessment model especially in missing cases with lots of variations and can also cause errors and confusion in interpreting the data. the missing data compromises the quality of the data, and in turn aects the accuracy of the model derived from the data (karim et al., 2017; silva-ramírez et al., 2011). unfortunately, missing data in the dataset have a negative impact on estimation accuracy and hence, may lead to inconsistent results. many estimation models cannot directly handle missing data values; therefore, the preprocessing stage becomes indispensable for modern estimation processes in software engineering (huang et al., 2017). thepreprocessingstepis theprocessneededtocleanandltertargetdatabecausedatacollectionisrarelycompleteandperfect (salleh and samat, 2017). so, the preprocessing method is an important role in the data mining task. preprocessing is an important step for ltering and cleaning the dataset before it can be trained at the data mining stage so that the data used is of best quality (crone and finlay, 2012). the ability to handle missing data has become a fundamental requirement for pattern classication, because improper treatment of missing data can lead to misclassication results (garcía et al., 2015). nowadays, most of the algorithms in datamininghave not been able to directly handle the problem of missing data. according to eekhout et al. (2014); poolsawad et al. (2012); vazifehdan et al. (2019), there are several techniques for handling missing data, namely; the rst is deletion, namely deleting an instant (record) or an incomplete attribute and the classication only uses the complete part of the data. the second is the imputation or estimation of missing data will be used in classication. the third is ignore, third is ignore, which is using data directly without handling missing data in a data set the simplest way to deal with this problem is deletion, i.e. deleting data that has missing data directly. however, this is only suitable for very small loss rates of 1-5% (vazifehdan et al., 2019). otherwise, if there is too much missing data on an attribute that there is little bit of information about the data, then the attribute can be removed from the data set because the information that attribute is incomplete (shah et al., 2017). removing missing data in a dataset sometimes has a negative impact on the accuracy of estimates and hence results in inconsistent results (lan et al., 2020). deletion has been widely adopted to handle missing data during data preprocessing (huang et al., 2017; malarvizhi and thanamani, 2012). the method of imputation missing data was to replace missing variables with value estimates that can maintain data completeness (choudhury and pal, 2019). the imputation method is a solution that can handle the problem of missing data where the missing data attribute is estimated or replaced by using various methods including statistical methods, such as mean or mode, machine learning, and others (garcía et al., 2015; luengo et al., 2011; tsai et al., 2018). there are some method and technique can use for imputation missing data. the simplest statistical method is mean method for numeric attribute and modes that focuses on the value of an attribute which appears frequently for imputation of category attribute (eekhout et al., 2014; mehrotra et al., 2017; nishanth and ravi, 2016; silva-ramírez et al., 2011). according to eekhout et al. (2014) the mean imputation can lead to biased estimates for each data scenario when the incidence of missing data in a domain is more than 10%. the mean imputation can also produce biased results if the observational needs a relational value between variables, because it does not consider the existing relational value variables (pedersen et al., 2017). another shortcoming is the mean method cannot be used to represent data for the values in the attribute are extreme. conversely, the mode is the easiest way to impute categorical data, but the results given will be biased if the mode value is more than one or even the mode value is not found in the attribute that has missing data. another disadvantage of the imputation mode is that it ignores the variance of the population or sample that exists (nishanth and ravi, 2016). the mean and mode methods are very suitable for imputation of missing data at a single value where the percentage of missing data is not too large. currently, more complex imputation approaches using machine learning approaches, such as randomforest (stekhovenandbühlmann,2012), neuralnetworks (nishanth and ravi, 2016; rahman and davis, 2012), k-nearest neighbor (knn) (manimekalai and kavitha, 2018), k-means (poolsawad et al., 2012), decision tree (chauhan et al., 2013), deep learning (ting et al., 2020). approaches with mechanical learning such as neural networks is an alternative to best imputation results but take more time than the statistical approach and it is not eective for small amounts of missing data (tsai et al., 2018). apart from deleting and estimating missing data by imputation, attribute selection also inuences the classication or prediction results. irrelevant attributes do not aect the description of target class. the redundant attributes do not contribute to anything but they create bias in the classication results (shilaskar and ghatol, 2013). according to pedro, at least 45% of the data set provided by the uci had a problem with missing data, including the heart data dataset. several studies to predict or classify heart disease disordered in the heart disease dataset both deal with missing data by signing it, deletion data, imputation data and elimination by using the selection attribute (attribute). al khaldy and © 2021 the authors. page 304 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 kambhampati (2016) predicted the pattern of heart disease by applying machine learning to predict heart disease problems regardless of the existence of missing data in the dataset. salleh and samat (2017) applied fuzzy c-means and particle swarm optimization to import missing data on heart disease dataset regardless of the percentage of missing data on each attribute. choudhury and pal (2019) showed that the neural network method had stable performance for attribute that have 1-10% missing data, but their performance greatly improved when working on attribute that have 50% missing data. unfortunately it did not explain how the data handler handled more than 50% of missing data. tsai et al. (2018) implemented imputation of missing data using class center method, namely by nding the center of each class and measuring the distance between classes to estimate the missing data threshold in the dataset. the accuracy in this study was only 78% without explaining the classication or prediction method used to detect cardiac disorders. silva-ramírez et al. (2011) applied a neural network to impute the missing data which amounts to no more than 5% but it did not explain the dierence in results if the missing data was only 1% or greater than 5%. subbalakshmi et al. (2011) combined several imputation methods, namely locf, mean-mode and iv but it did not explain the imputation method used by each attribute. hernández-pereira et al. (2015) compared mean or mode imputation, multiple linear regression, hot-deck, k-nn, and neural network (nn) to handle missing data. the result of in this study showed that the performance of nn provides the best performance for handling missing data. several studies conducted deletion of data on attributes that deemed to have less signicant inuence on heart disease dataset (el-bialy et al., 2015; long et al., 2015). the heart disease dataset has several attributes that have dierent amounts of missing data. the study focused how to handle the missing data on heart disease dataset and tried to use multiple ways to overcome the problem. this study was not only use one technique or method for some attributes but it used multiple ways namely deletion technique, mean, mode and articial neural network methods for imputation missing data. this study tried to get the advantages of each technique and methods to solve the problem of missing data. the deletion technique was used in the study for attributes where the amount of missing data was more than 70% because the information available for the attribute was considered insucient. the mean and mode methods used for attribute that had missing data lower or equal with 1%, because mean or mode method are suitable for missing data with a single value and the amount of missing data is not too much (nishanth and ravi, 2016). for attribute that had amount of missing data more than 1%, the study used articial neural network because some researches has been showed than articial neural network (ann) method was greatly to impute missing data that had amount more than 1% (choudhury and pal, 2019; tsai et al., 2018). the utilization for each technique and methods in the study was adjusted to the percentage amount of missing data from each attribute in the dataset at the pre-processing step to get best data quality and provide best results in classication. performance measurements of a classication method that were usually used include accuracy, specicity, sensitivity and roc (desiani et al., 2021; resti et al., 2021). this study used accuracy, specicity, sensitivity and roc to measure the performance classication in the proposed method. 2. experimental section 2.1 materials in this research used secondary data, namely data on patients with heart disease obtained from the university of california irvine (uci) machine learning repository which can be downloaded at their ocial website (statlog, 2004). data were obtained from 294 patients suspected of having heart disease. the data contains 14 attributes that are used as inuential attributes in diagnosing heart disease, among others age, gender, type of chest pain, blood pressure, cholesterol, sugar levels, electrocardiography, maximal heart rate, induced angina, old peak, slope, uoroscopy, heart rate and attributes as labels containing the categories healthy and sick. all attributes and values and types of each attribute can be seen in table 1. 2.2 methods all of stages of the proposed method in the study can be seen in figure 2. the stages are : 2.2.1 handling missing data deletion, the attributes that have a percentage of missing datas of more than 70% are deleted and dropped from the data set because they are considered not representative and have insufcient information. attributes that have missing data of less than 70% will be imputed missing data. mean and mode imputation, the mean method that has number of missing data less than 1% will be predicted using calculate mean of the attribute or attribute with categorical type that has number of missing datas less than 1% of the total data will be predicted using the mode imputation. for attribute with numeric (integer or real) that has number of missing data less than 1% will be predicted using calculate mean of the attribute. articial neural network imputation, for missing data with an amount of more than 1%, it will be imputed using a articial neural network (ann). in this step, data will be split into 2 group, rst was data training and the second as data testing. the ann for this step was used 3 layers, namely input layer, one hidden layer and output layer (figure 1). the rst step that must be done in the training stage is normalizing the input data only for the continue or numeric attribute on the dataset, because the data range for the continue attribute is dierent so the data must be normalized by x′i = xi − a b − a (1) next initialize the weights for each input and bias in figure 1 associated with the hidden layer. then calculate the input © 2021 the authors. page 305 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 figure 1. articial neural network with 3 layers value for each unit using equation (2) based on figure 1, is the jth neuron in the hidden layer. zinj = n∑︁ i=1 wjix ′ i + bj (2) where wji is the weight for the i-th neuron in the input layer and the j-th neuron in the hidden layer and bj is the bias to calculate zj . after that, calculate all the activation values as the output of each hidden layer (𝜙h) to the output layer (y) with the sigmoid function as the activation function in equation (3). next step is calculate the input value (yinj) for the output layer using equation (4). 𝜙h = 1 1 + e−zinj (3) yinj = p∑︁ j=1 vkjzj + bk (4) where vkj is weight for the j-th on hidden layer and the k-th neuron on output layer. bk is bias is a bias to calculate yk . after that, calculate activation function (𝜙o) as input for output layer (yinj) on every the j-th of input using equation (5). 𝜙o = 1 1 + e−yinj (5) perform the backpropagation of error stage by calculating the unit error factor (𝛿) based on the error on input (yink) on output layer for each output )yk with equation (6). 𝛿k = (tk − 𝜙o) f ′(yink) = (tk − 𝜙o)yk(1 − 𝜙o) (6) 𝛿k is the error unit that will be used in changing the layer weight with (tk) being the k-th output target. next step is calculate the value of the weight change (δvkj) in equation (7) which is used to update the weight value of vkj on the hidden layer zj based on the activation value (𝜙o) that has been calculated previously, with the learning rate acceleration (𝛼=0.1) δvkj = 𝛼𝛿kzj (7) calculate the value of the change in bias (δbk) which is used to update the bias value bk at the output layer y based on the value of learning rate and unit error (𝛿k) and calculate the unit error (𝛿inj) that comes from the output layer to the hidden layer using equation (9). δbk = 𝛼𝛿kzj (8) 𝛿inj = m∑︁ k=1 𝛿kvkj (9) next, it should calculate the hidden unit error (𝛿 j) in the hidden layer using equation (10) and calculate the change weight value of w which is then used to update the weight value of wi j. 𝛿 j = 𝛿inj f ′(zinj) (10) δwi j = 𝛼𝛿 jxi (11) for the bias, calculate the value of the change in bias (δbj) based on the unit error (𝛿 j) on hidden layer. after that, update each bias and weight on the hidden layer with the equation (13) and update each bias and weight on the hidden layer with the equation (14). δbj = 𝛼𝛿 j (12) wji (new) = wji (old) + δwji (13) vkj(new) = vkj(old) + δvkj (14) update the weight on the bias by using equation (15) to obtain the new bias weight value (bj(new)) in the hidden layer and equation (16) for the new bias weight value (bk(new)) in the output layer. the calculation steps for the training phase are carried out on all existing input data until the weights no longer experience signicant dierences or depend on the epoch specied for each attribute. bj(new) = bj(old) + δbj (15) © 2021 the authors. page 306 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 bk(new) = bk(old) + δbk (16) at this testing phase , the weights generated by the ann were applied to the testing data to test the performance results of the ann. the steps needed were to take the last weight at the training stage and classify it with equations (2) and (4) then compared the labels of the classication results with the original labels of the data. the comparison is used to measure the results in the accuracy, specicity (sp), and sensitivity (sn) performance for ann. another way to the measure the ann performance for every attribute, the label classication in each method was compared with the original label to calculate the dierence or error that occurs. the error is calculated based on mse. the smaller value of mse, it can be considered that the network architecture is better (saputra et al., 2017). the value of mse could be calculated using the following equation (17). mse = n∑︁ i=1 (yi − ŷ) n (17) where yi was the output label on the data set which had n quantities and (̂y) was the predictive value of the model. 2.2.2 filling imputation result the results of imputation missing data were put back to each attribute that has amissingdata, so that the dataset had no more missing data or in another word the dataset was completed. 2.2.3 analysis at this stage, testing of the complete dataset is carried out by calculating the resulting performance of classication methods namely accuracy, specicity (sp), sensitivity (sn) and roc. the methods that used for classication on complete dataset were articial neural network (ann), naïve bayes, support vector machine (svm) and k-nearest neighbor (knn). the completed data was divided using a percentage split, which was 80% as training data and 20% as testing data. in naïve bayes, it used gaussian naïve bayes. gaussian naïve bayes was used because the dataset consists of categories and continuous types data, while in svm, it use the one agains one method because the label on the data was binary (2 labels). in the knn method, it used k = 3. this has been proven during trials by giving dierent k values (1-8). at the value of k = 3 the performance value of knn gave the highest results and decreased for k>3. the ann at this stage used an architecture similar to the ann at the imputation stage of missing data using figure 2. 3. results and discussion 3.1 attributes deletion the 14 attributes in the dataset were calculated for the presentation of each of the total number of existing data. the attributes that had missing data and their percentages could be figure 2. the stages in proposed method seen in table 1. from table 1 it could be seen that the backup attribute had a very large missing data, namely ca attribute and thal attribute. ca attribute had 98.97% missing data and thal had 90.47% missing. it mean that there were a lot of lack of information that we got from these two attributes so that the attributes were dropped and deleted from the dataset. meanwhile, 7 other attributes had missing data which was still quite low below 70%. 3.2 imputation of missing data 3.2.1 attributes with less than 1% missing data from table 1, it was known that the veryfewattributes that had missingdata (under1%) were the trestbps, restecg, thalac and exang attributes so that to predict missing data in the data set, it was enough to use a simple method, namely the mean (for continuous or numeric data types) and the mode for data of type category. trestbps and thalac imputed missing data using the mean method because they each has only had 1 missing data of the total 249 available data. bymean xxx, the missing data for trestbps was obtained x̂=132.58 and missing data for thalac was x̂=139.13 . for attributes of type category such as restecg and exang, the mode value was be used to import the missing data. the restecg attribute had 3 types of data, namely 0 for normal. 1 for st-t wave abnormalities and 2 for left ventricular hypertrophy. in the restecg attribute the value of the most data was owned by the normal label (0), then the missing data in the restecg attribute was lled with the label 0.the exang attribute had two labels 0 for no and 1 for yes. 0 label was as many as 204 data and 1 label was as many as 89 data. the mode in exang attribute was 0 label then the missing data was imputed with a 0 label. 3.2.2 attributes with more than 1% missing data forimputationonattributes thatuseann, theattributeof type numeric or continuous must be changed to categorical form because they would be used as classication labels on training stage. there were three attributes with missing data above © 2021 the authors. page 307 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 table 1. attributes, values, total and percentage of missing data of heart disease dataset attributes values number of percentage of missing data missing data (%) age in years 0 0 sex male, female 0 0 chest pain abnang, angina, 0 0 type (cp) asympt, notang trestbps 94,0 200,0 1 0.34 cholesterol (chol) 126,0 564,0 23 7.82 fasting blood sugar (fbs) true, false 8 2.72 resting ecg (restecg) norm, hyp, abn 1 0.34 max heart rate (thalach) 99,0 103,0 1 0.34 exercise induced true, false 1 0.34 angina (exang) oldpeak 0,0 6,2 0 0 slope down, flat, up 190 64.4 number of 0,0 3,0 291 98.97 vessels colored (ca) thal normal, rever, fixed 266 90.47 diagnosis of healthy, sick 0 0heart disease (num) 1%, namely attributes of fasting blood sugar (fbs), cholesterol (chol) and slope so the ann imputation were applied for the attributes. the fbs attribute had missing data as much as 8 data and has two categories, namely patients who had blood sugar > 120 mg/dl with 2 categories, there were 1 to state the patient had blood sugar > 120 mg/dl and 0 to state the patient’s blood sugar <120 mg/dl. cholesterol (chol) attribute was cholesterol of a patient that had in mg/dl and the attribute had 23 missing data. chol had a continuous data type, which could be predicted using articial neural network (ann). data on chol attribute should be converted into categories as label data. chol attribute could be categorized into 3 labels very high(0) : > 200 mg / dl, high(1): 160-200 mg / dl, normal (2): <160 mg / dl (rahakbauw et al., 2016). for slope attribute, it was used to represent the slope of the st segment at (peak). there were three labels, namely 1: up, 2: at, 3: down. missing data on the slope attribute was 114 data. the imputation using ann were applied for each attribute (fbs, chol and slope) to guess missing data on the attribute. the results of imputation using ann were measured based on the values of accuracy, sp, sn and mse generated by each attribute. the results of these measurements could be seen in figure 3. in figure 3 it could be seen that ann worked very well in imputing missing data on the fbs attribute with an accuracy of 95.46, sp of 97.69, sn of 62.5 and mse of 0.06. while on the chol attribute the measurement results were quite good with an accuracy of 75.75% and an mse of 0.0765, but the specicity and sensitivity were still low below 60%. the results of the ann imputation on the slope attribute were quite low where the accuracy and sensitivity values were figure 3. comparison of accuracy, specicity (sp), sensitvity (sn) and mse for imputation still below 60% but the resulting specicity was quite good at 74.62%. the result of attributes deletion and imputation method would applied into heart disease dataset. the data that has been obtained from the handling missing data was returned into initial dataset. thus, the new dataset did not have missing data and total number of data used for classication was 294 patient data with 12 attributes where 11 attributes as input and 1 attribute as labels (num attribute). the label num contained 2 categories, 0 for healthy and 1 for sick. after the process of lling in the imputed data, the results are entered into the data set. the next process was to apply classication methods into heart disease dataset to see the eect of handling missing data with deletion and imputation methods on classication process. 3.3 filling in imputation missing data to dataset the data that has been obtained from the results of technique and method of handling missing data on returned into the © 2021 the authors. page 308 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 table 2. comparison of research results on the proposed method with previous research the handle missing data method data set prediction method sn sp accuracy roc a hybrid bayesian network breast cancer c45 78.55 92.83 89.29and tensor factorization approach (vazifehdan et al., 2019) fuzzy c-means and framingham decision tree 0.846 86.3 0.83particle swarm optimization heart (salleh and samat, 2017) not handling missing heart disease naïve bayes 82.3 0.845 81.97 data (apurb et al., 2020) ann and t-test attribute heart failure ann 76.8 0.803 selection (poolsawad et al., 2012) ann and nonlinear heart failure ann 69.5 0.769 -gain analysis attribute selection (poolsawad et al., 2012) svm imputation cleveland random forest 97.1 48.51 84.97 (al khaldy and kambhampati, 2016) heart failure chaos rey algorithm heart interval 84.9 93.3 88.3and rough sets based disease type-2 fuzzy attribute reduction (long et al., 2015) dataset logic system k-means clustering wisconsin ann 99.91 99.54 99.39 1 (purwar and singh, 2015) breast cancer articial neural network respiratory neural 69.63 84.44 79.03 80 (hernández-pereira et al., 2015) miasoft network feed maximum likelihood hungarian batch 36.51 99.86 99.86 (misir and samanta., 2017) data set backpropagation fuzzy k-mean clustering cardiovascular decision tree 30 0.7 0.64 (rahman and davis, 2012) a combination of internet random forest 99 1 99.43 0split data and fkmeans of thing (vangipuram et al., 2020) rened mean substitution breast cancer fuzzy c-means 95.29 85.75 91.73 (somasundaram and nedunchezhian, 2012) proposed method heart disease neural network 94.2 94.2 94.23 0 proposed method heart disease naïve bayes 87.76 87.6 87.5 0 proposed method heart disease svm 90 90 90 84 proposed method heart disease knn 90.48 0.905 90 90 initial dataset. thus, the new dataset did not have missing value. after the process of lling in the data imputation results into the data set, the next process was to classify heart disease on the new dataset to see the eect of handling missing data on classication of heart disease. the total number of data used for classication was 294 patient data with 12 attributes whereas 11 attributes as input and 1 attribute as label namely num attribute. the num contained 2 categories, 0 for healthy and 1 for sick as a label in dataset. 3.4 disccussion in this study the data from the proposed method were applied to several kinds of classication methods. the results of the imputation of missing data using deletion, mean, mode and ann techniques were analyzed to see if they were able to improve performance on classication using the ann, naïve bayes, svm, and knn methods. to analyze the eect of imputation on missing data. the new dataset was tested using several methods, namely the ann, naïve bayes, support vector machine (svm) and knn to see the eect of missing data imputation on the performance of classication methods. the results of classication testing showed that missing data imputation increased the accuracy, sensitivity (sn) and specicity (sp) for each method. figure 4 showed that there was an increase for accuracy, sn and sp in the new dataset. from figure 4, it could be seen that the highest increase was obtained in classication using the ann. the comparison of results classication on the data before andafterhandlingmissingdatawasnot sucient toevaluate the © 2021 the authors. page 309 of 312 desiani et. al. science and technology indonesia, 6 (2021) 303-312 figure 4. comparison of accuracy, specicity (sp) and sensitivity (sn) in prediction of heart disease dataset success without comparing the results of the proposed method with other methods carried out in other studies. the results of this research were also compared with some other studies. table 2 showed several studies using various techniques to deal with the problem of missing data by using various data sets, either heart disease by uci or other datasets. from table 2, the highest accuracy, sn and sp values were obtained by purwar and singh (2015), even the roc value obtained at the highest value, but the missing data in the study was only 16 out of 569 data. the study by vangipuram et al. (2020) also had the highest test results compared to other studies, but the total missing data was only 0.072% of 2050 total data from 12 attributes. the test results on al khaldy and kambhampati (2016) also had higher accuracy than the accuracy of the proposed method, but the specicity value was lower than the specicity on the proposed method. the accuracy in the subbalakshmi et al. (2011) was also very high, but unfortunately the sn value obtained was very small. from table 2 it could be seen that the results of the accuracy of the proposed method were better than several other studies. the results of the sensitivity and specicity of the proposed method were also good, it was seen that the values obtained were higher and balanced than the other studies. several previous studies did not show the sensitivity value obtained, some other studies also did not show the accuracy or roc result that was successfully obtained in the study. from this comparison, it could be concluded that the proposed method was very suitable to be used for imputing missing data and could increase the accuracy, sensitivity, and specicity values which were very good above 85% by dierent classication methods. 4. conclusions the handling missing data in the study used 3 ways, rst deletion technique for attributes that had missing data more than 70%. the second was the mean for numeric or continue data and mode imputation method for category data to handle missing data which the amount missing data was less or not more than 1%, namely the trestbps and thalac attributes by mean method, restecg and exang attributes by mode method. the third method was articial neural network (ann) for attributes that had total missing data more than 1%, namely fbs, chol, and slope attributes. the resulting mse shows that ann was very good to impute missing data on the fbs and chol attributes where the resulting mse results were relatively small. but for imputing missing data on the slope attribute, ann was less suitable for use because the mse result for the attribute was still relatively big. the performance showed the imputation results of the fbs and chol attributes by ann better than other methods. it could be seen from the accuracy obtained above 75%. unfortunately, the accuracy obtained by the slope attribute was not very satisfying, it is only 52%. although the performance results on the slope attribute from both mse and confusion matrix measurements were not satisfactory, the results of imputation carried out with the proposed method could improve and increase the accuracy, sensitivity (sn) and specicity (sp) of classication performance on the uci heart disease data set. the classication performance of ann, naïve bayes, svm and knn proofed that their performance has been increased when the methods worked on new dataset that has been handled the missing data problem compared theirs performance on original dataset. this research can be developed furtherbyapplyingother imputation methods formissing data, especially for the slope attribute which has a low accuracy value and a large mse. 5. acknowledgement the authors thank to the deep learning discussion group for all the support on our research. references al khaldy, m. and c. kambhampati (2016). performance analysis of various missing value imputation methods on heart failure dataset. proceedings of sai intelligent systems conference; 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175–184 zriqat, i. a., a. m. altamimi, and m. azzeh (2016). acomparative study for predicting heart diseases using data mining classication methods. international journal of computer science and information security, 14(12); 868–879 © 2021 the authors. page 312 of 312 introduction experimental section materials methods handling missing data filling imputation result analysis results and discussion attributes deletion imputation of missing data attributes with less than 1% missing data attributes with more than 1% missing data filling in imputation missing data to dataset disccussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper innovative modified of cu-al/c (c = biochar, graphite) composites for removal of procion red from aqueous solution alfan wijaya1, patimah mega syah bahar nur siregar2, aldi priambodo1, neza rahayu palapa1,3, tarmizi taher4, aldes lesbani1,3* 1research center of inorganic materials and complexes, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30139, indonesia2magister programme graduate school of mathematics and natural sciences, universitas sriwijaya, palembang, 30139, indonesia3graduate school, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30139, indonesia4department of environmental engineering, institut teknologi sumatera, lampung selatan, 35365, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstractinnovative modification of cu-al/c composites was synthesized by coprecipitation method at ph 10 and added biochar (bc) andgraphite (gf) to form cu-al/bc and cu-al/gf composites. pristine and composites were characterized by xrd, ft-ir, thermalgravi-metric, and surface area using the bet method. the xrd diffraction and ftir spectrum of cu-al/bc and cu-al/gf showed that thecomposite material from ldh, biochar, and graphite was successfully prepared. modified ldh were surface area higher than thepristine, which obtained 200.90 m2/g and 18.83 m2/g for cu-al/bc and cu-al/gf respectively. cu-al/bc and cu-al/gf were testedfor selectivity on several anionic dyes, it was known that procion red (pr) dye was more easily adsorbed than other anionic dyes.materials were applied as adsorbents of procion red (pr) dye. the advantages of composites were evaluated by the regenerationprocess of adsorbent on pr. the result of composite toward pr re-adsorption process showed that cu-al/bc and cu-al/gf hadstructural stability higher than starting materials until five cycles process. furthermore, materials were applied as adsorbents ofprocion red (pr) dye. the maximum adsorption capacity obtained was 93.458 mg/g for cu-al/bc and 49.505 mg/g for cu-al/gf.both innovative modified composites have shown effective adsorbents to the removal of pr from an aqueous solution. keywordscomposites, adsorption, procion red dye, selectivity, structural stability received: 27 april 2021, accepted: 17 july 2021 https://doi.org/10.26554/sti.2021.6.4.228-234 1. introduction synthetic dyes have become widely used due to their being more durable, more colorful, low cost, and easy to apply on domestic and industrial scales (lellis et al., 2019). the increasing use of synthetic dyes can create several disadvantages not only for the environment but also for human health. the wastewater of synthetic dyes is an organic pollutant that is dicult to degrade by nature (eltaweil et al., 2020). one of the synthetic dyes that are intensively used in industrial applications is procion red (pr) (hua et al., 2020). the structure of pr is shown in figure 1. toxicity of pr thus removal of pr was vital. various methods to remove dyes wastewater such as photocatalytic degradation (kumar and rao, 2017; natarajan et al., 2020), biological treatment (tang et al., 2020; sarkar et al., 2017), coagulation (mcyotto et al., 2021; demissie et al., 2021), and adsorption (palapa et al., 2018; palapa et al., 2020a; siregar et al., 2021) have been tested. adsorption is a method that is widely used figure 1. chemical structure of procion red (pr) to remove dyes due more ecient, fast process, and cheap (eltaweil et al., 2020). many adsorbents can be used to absorb dyes such as kaolin (mustapha et al., 2019), activated carbon (quesada et al., 2020; streit et al., 2019), bentonite (mohammadetal.,2020), chitosan(shietal.,2020), andldh (layered double hydroxide) (palapa et al., 2019; zhao et al., 2017; palapa et al., 2020b; siregar et al., 2021; normah et al., 2021; juleanti et al., 2021). layered double hydroxide (ldh) https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.228-234&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.228-234 wijaya et. al. science and technology indonesia, 6 (2021) 228-234 has high ion exchange and adsorption ability making ldh an appropriate adsorbent for adsorption of various pollutants. ldh has a granular structure and a less stable structure. these properties make the limitation of ldh an adsorbent, especially for the reusability process. research conducted by palapa et al. (2018) using ni/al and zn/al ldhs to adsorb direct yellow dye showed the ecient process of adsorption. cu/al ldh was applied to adsorb malachite green dye with also ecient results (palapa et al., 2020b). zn/fe and zn/al were used as ecient adsorbents to adsorb direct yellow dye (palapa et al., 2019), and mg/al ldh to adsorb methylene blue dye (zhao et al., 2017). all results showed that ldh has a limitation as adsorbent for reuse process, thus modication of ldh is needed to enhance the ability of ldh for dyes adsorption. by modication of ldh through impregnation by carbon-based materials can create the structure stability and performance of ldh. one of the potential carbon materials for ldh support is biochar (bc) and graphite (gf). composite of cu-al/bc was prepared as adsorbent of malachite green produce an adsorption capacity of 108.96 mg/l (palapa et al., 2020b). mg/al-bc composite was also successfully used as an adsorbent of malachite green with an adsorption capacity of 70.922 mg/g (badri et al., 2021) and mg/al-carbondotcompositewassynthesizedtoadsorbmethylene blue with an adsorption capacityof 185 mg/g (zhanget al., 2014). in this research, cu-al/bc and cu-al/gf composites are prepared, used as adsorbents, and tested for selectivity on several anionic dyes to know which dyes are more easily adsorbed. the adsorption parameters to be studied in this study include adsorption isotherms and adsorption thermodynamics which are calculated using the langmuir and freundlich equation. the stability of composites is evaluated by regeneration of adsorbent until ve cycles adsorption process. 2. experimental section 2.1 chemicals and instrumentation the chemicals used in the experiment were cu(no3)2.3h2o byemsure®acs,al(no3)3.9h2obysigmaaldrich,naoh by emsure® acs, rice husk was obtained from bukata organic®, indonesia, fabricant graphite from sigma aldrich and water was demineralized using purite® water purication apparatus. pristine and composites were characterized by xrd, ftir, and bet. analysis xrd was performed by rigaku miniex-6000 diractometer. ft-ir characterization using ft-ir shimadzu prestige-21. analysis bet using quantachrome micrometic asap. the concentration of pr was analyzed using spectrophotometer ultra violet-visible biobase bk-uv 1800 pc at a wavelength of 545 nm. 2.2 preparation of cu/al ldh synthesis of cu/al ldh was conducted as a similar procedure by palapa et al. (2020b) using the coprecipitation method at ph 10. the synthesis of cu/al ldh was carried out in the following procedure: as much as 100 ml of cu(no3)2.3h2o 0.75 m was mixed with 100 ml al(no3)3.9h2o 0.25 m (3:1) in a beaker. the reaction was stirred until homogeneous mixtures then 50 ml naoh 2 m was added until ph 10. the mixture was stirred for 20 hours. the solid precipitate was then ltered, washed and dried at 110°c for 120 minutes. 2.3 preparation of cu-al/bc and cu-al/gf cu-al/bc and cu-al/gf composites were prepared using the coprecipitation method in the following procedure: as much as 10 ml cu(no3)2.3h2o 0.75 m mixed with 10 ml al(no3)3.9h2o 0.25 m and stirred for 60 minutes until homogeneous. the resulting mixture was added with 1 g of (bc or gf) while stirring and added with naoh 2 m until ph 10. the mixed solution was stirred for 3 days at a temperature of 80 °c. the composites were ltered, washed and dried at 40 °c for 120 minutes. 2.4 selectivity of anionic dye mixtures the selectivity of anionic dye mixtures was carried out to nd the most widely absorbed anionic dyes in each adsorbent by mixing anionic dyes of congo red (cr), procion red (pr), methyl orange (mo) and methyl red (mr) with the same concentration, then added adsorbents and stirred with a time variation of 15, 30, 60, 90, and 120 minutes, then measured absorbance at the wavelength of each dye. 2.5 desorption and regeneration of adsorbent the desorption process was carried out to test the adsorbent eciency for the reuse of the adsorbent. in this study, the desorption process was used as an ultrasonic process. the desorption process was carried out using 50 ml of pr. as much as 50 mg/l was added with 1 g of adsorbent and stirred for120 minutes. then, dry the used adsorbent and take 0.01 g, add 10 mlof water to the ultrasonic process. the regeneration process using the adsorbent that has been used is as follows: 50 ml of pr at 50 mg/l was stirred for 120 minutes and solution was measured using a uv-vis spectrophotometer at 545 nm. the dried adsorbent was then used again for the desorption process, successively. the adsorbent was applied until ve cycles adsorption process with the same procedure as the initial run. 2.6 adsorption process theadsorptionprocessofprwasstudiedthroughthe inuence of the initial concentration of pr and adsorption temperature. the variation of initial concentration of pr and temperature adsorption was carried out with the concentration of cr (60, 70, 80, 90 and 100) mg/l, 0.02 g of adsorbent and 20 ml of pr, then stirred for 100 minutes with a variation of the adsorption temperature at 30, 40, 50, and 60 ºc. the concentration of the pr was measured by uv-vis spectrophotometer at 545 nm. thermodynamic parameters were obtained from the langmuir and freundlich equations. langmuir is assumed to be a chemical and monolayer adsorption process, while freundlich is assumed to be a physical and multilayer adsorption © 2021 the authors. page 229 of 234 wijaya et. al. science and technology indonesia, 6 (2021) 228-234 process. isotherm langmuir and freundlich’s equations are according to previous works of literature (palapa et al., 2020b). 3. results and discussion diractogram of cu/al ldh, bc, gf and composites are shown in figure 2. cu/al ldh materials have typical peaks with good crystallinity with diraction angles at 11.6° (003), 23.5° (006), 34.3° (101), 35.1° (012), 37.8° (104), 39.8° (015), 44.4° (107), 47.3° (018) and 61.4° (110/113) indicated that the formation of the cu/al ldh structure was following the jcpds 46-0099 le. figure 2b showed that broad peak the presence of high carbon content on bc with diraction at 22.30° (002). the diraction patterns of gf as shown in figure 2c, material has good crystallinity with diraction at 26.4° (002). the diraction patterns of cu-al/bc as shown in figure 2d resemble the diraction patterns of cu/al ldh and biochar. the cu-al/bc composite material has an amorphous diraction pattern due to the characteristics of biochar with a diraction peak of around 23°. the diraction pattern in cu-al/gf as shown in figure 2e resemble that of cu/al ldh and graphite. cu-al/gfcomposite material is shown in figure 2e which shows that there are typical peaks of cu/al ldh and graphite. according to kusrini et al. (2019) cu-al/gf composite material has a distinctive diraction pattern of graphite around 26.54° (002) with sharp peaks. figure 2. xrd powder patterns of cu/al ldh (a), bc (b), gf (c), cu-al/bc (d), and cu-al/gf (e) nitrogen adsorption-desorption analysis on cu/al ldh, bc, gf and cu-al/bc and cu-al/gf composites is shown in figure 3. figure 3 shows that the nitrogen adsorption pathway is not the same as the nitrogen desorption pathway which indicates that the material has hysteresis. the hysteresis that occurs in the graph shows the pores in the material. the pattern in figure 3 shows that the materials in cu/al ldh, bc, gf, cual/bc and cu-al/gf composites follow type iv isotherms. type iv isotherm shows hysteresis of mesoporous sized materials with strong hysteresis activity on the adsorbent-adsorbate interaction. table 1 showed that cu-al/bc had surface area four-fold than pristine ldh and bc. the results of the bet analysis figure 3. bet prole of cu-al ldh (a), bc (b), gf (c), cu-al/bc (d), and cu-al/gf (e) showed that the starting material had an increase in surface area after the formation of composites which obtained 200.90 and 18.83 m2/g for cu-al/bc and cu-al/gf respectively. this shows that the synthesis process has been successful. table 1. bet analysis of materials materials surface area pore size pore volume (m2/g) (nm), bjh (cm2/g),bjh cu-al ldh 46.279 10.393 0.116 bc 50.936 12.089 0,025 gf 9.394 3.169 0.027 cu-al/bc 200.90 7.03 0.350 cu-al/gf 18.83 3.132 0.046 figure 4a shows the ftir spectrum of cu/al ldh had vibrations at 3448 cm−1 which indicates the presence of oh stretching, 1635 cm−1 presence of o-h bending, 1381 cm−1 presence of n-o stretching, 794 cm−1 presence of alo and 462 cm−1 presence of zn-o and cu-o. the ftir spectrum of bc and cu-al/bc as shown in figures 4b and 4d had vibrations that indicate the presence of o-h stretching, c-h bending, o-h bending, and c-o stretching. the ftir spectrum of gf and cu-al/gf as shown in figures 4c and 4e had vibrations presence of o-h stretching, vibrations at 2368 cm−1 presence of c-h, o-h bending, n-o, zn-o and cu-o. composites of cu-al/bc and cu-al/gf had all vibrations of cu-al ldh, bc, and gf as a result of two components were involved in the composites. figure5showedthethermalanalysisofmaterials. thethermogravimetry of cu/al ldh patterns had only an exothermic phase because cu/al ldh consists of inorganic components. the exothermic peak of cu/al ldh was attributed to the decomposition of water at around 110 °c, decomposition of a layer at around 650 °c, and loss of anions on interlayer at around 200-300 °c. bc had organic content thus endother© 2021 the authors. page 230 of 234 wijaya et. al. science and technology indonesia, 6 (2021) 228-234 figure 4. ftir spectrum of cu/al ldh (a), bc (b), gf (c), cu-al/bc (d), and cu-al/gf (e) figure 5. thermal prole of cu/al ldh (a), bc (b), gf (c), cu-al/bc (d), and cu-al/gf (e) mic peak was found due to oxidation of organic parts around 490 °c. gf has only one decomposition peak at 760 °c. this decomposition peak was denoted that gf was pure without other ingredients, including water. cu-al/bc and cu-al/gf composites had organic and inorganic components thus had two kinds of endothermic and exothermic peaks. table 2 shows the adsorption concentration of each dye in the selectivity of anionic dye mixtures. based on the data in table 2, the concentration of pr adsorption is greater compared to other dyes. this suggests that pr is more easily to adsorption process using cu-al/bc and cu-al/gf adsorbents. the results of the regeneration of each adsorbent on the pr dye can be seen in figure 6. as an equal result of increasing surface area properties after the formation of composite cual/bc thus adsorption of prwas higher than starting materials. starting materials of cu/al ldh had a less stable structure so modications of composites based on carbon materials such as bc and gf to produce a stable structure that can be reused figure 6. regeneration of adsorbents figure 7. eect of initial concentration of pr and adsorption temperature on cu-al/bc (a) and cu-al/gf (b) on the adsorption process. the result of the composites regeneration process on pr showed that cu-al/bc and cu-al/gf had structural stability higher than starting materials. eect of initial concentration of pr and adsorption temperature on cu/albc and cu-al/gfas shown in figure 7. increasing the adsorption temperature will increase the adsorption capacity. table3presents the isothermadsorptionparameters, which identies that thelangmuirmodel isbetter thanthefreundlich model. the langmuir model indicates the adsorption process is a monolayer. table 3 showed that the maximum adsorption capacity of cu-al/bc is larger than other materials that so it has high eectivity on cr adsorption. table 4 showed the thermodynamic adsorption of cr. the δh had positive values indicated that adsorption occurs endothermically which requires an energy of adsorption process. the value of δg was more negative with increasing temperature indicated that adsorption on all materials was spontaneous. the value of δs indicated the degree of irregularity. the positive value of δs indicates that an increase in irregularity on the surface. in table 5, cu-al/bc and cu-al/gf composites had the highest adsorption capacity than several adsorbents. thus materials were eective adsorbents to the removal of pr from aqueous solution. © 2021 the authors. page 231 of 234 wijaya et. al. science and technology indonesia, 6 (2021) 228-234 table 2. selectivity of anionic dye mixtures adsorbents times concentration adsorption (mg/l) (minutes) mr mo pr cr cu-al/bc 0 0.000 0.000 0.000 0.000 15 0.672 0.095 1.519 0.476 30 3.507 0.587 8.228 1.349 60 5.149 1.591 15.063 3.492 90 5.821 2.008 25.443 5.556 120 6.791 2.140 36.203 7.619 cu-al/gf 0 0.000 0.000 0.000 0.000 15 0.597 0.303 0.127 0.317 30 0.896 1.420 7.848 1.190 60 2.836 1.591 10.000 3.095 90 4.179 1.818 11.772 3.413 120 5.746 1.837 13.418 3.651 table 3. isotherm adsorption adsorbents adsorption adsorption t (°c) isotherm constant 30 40 50 60 cu-al/bc langmuir qmax 53.476 63.291 81.301 93.458 kl 0.066 0.074 0.081 0.106 r2 0.984 0.995 0.998 0.995 freundlich n 3.425 3.667 3.801 4.507 kf 13.107 15.160 16.939 21.023 r2 0.845 0.929 0.984 0.977 cu-al/gf langmuir qmax 46.296 46.512 47.393 49.505 kl 0.060 0.084 0.114 0.132 r2 0.992 0.992 0.999 0.999 freundlich n 3.576 4.216 5.157 5.596 kf 11.564 14.800 18.897 21.340 r2 0.911 0.871 0.941 0.936 table 4. thermodynamic adsorption adsorbents t (k) qe (mg/g) δh δs δg (kj/mol) (j/mol.k) (kj/mol) cu-al/bc 303 32.911 15.041 0.051 -0.423 313 35.443 -0.934 323 37.975 -1.444 333 40.633 -1.955 cu-al/gf 303 29.367 14.327 0.047 0.157 313 31.772 -0.311 323 34.810 -0.779 333 36.835 -1.246 © 2021 the authors. page 232 of 234 wijaya et. al. science and technology indonesia, 6 (2021) 228-234 table 5. adsorption of pr by several adsorbents materials adsorption capacity references(mg/g) corncob activated carbon 2.86 (nazifa et al., 2018) spent tea leaves 3.28 (heraldy et al., 2016) waste fe (iii)/cr (iii) hydroxide 3.28 (namasivayam and sumithra, 2006) agricultural wastes 6.12 (nor et al., 2015) raw and acid-treated montmorillonite k10 11.04 (sarma et al., 2018) lua cylindrica 13.9 (oliveira et al., 2011) cornstalk 15.9 (valencia et al., 2001) sewage sludge ash (ssa) 28.82 (hu and hu, 2014) cu-al/bc 93.458 this research cu-al/gf 49.505 this research 4. conclusions innovative modication of cu-al/bc and cu-al/gf composites was successfully formed. the surface area properties of cual/bcandcu-al/gfwere largerthanstartingmaterials, which obtained 200.90 m2/g and 18.83 m2/g respectively. based on the selectivity test for anionic dye mixtures, it is known that pr is more easily adsorbed than other anionic dyes. cu-al/bc and cu-al/gf composites were high structural stability on pr re-adsorption process until ve cycles process. the maximum adsorption capacity 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277–287 tang, r., y. wang, s. yuan, w. wang, z. yue, x. zhan, and z.-h. hu (2020). organoarsenic feed additives in biological wastewater treatment processes: removal, biotransformation, and associated impacts. journal of hazardous materials; 124789 valencia, s., m. pascua, j. movillon, and h. braza (2001). adsorption of basic rhodamine red, basic methylene blue, reactiveprocionred, andreactiveprocionblue textiledyesby cornstalk. philippine agricultural scientist (philippines), 84(3); 304–312 zhang,m.,q.yao,c.lu,z.li, andw.wang(2014). layered double hydroxide–carbon dot composite: high-performance adsorbent for removal of anionic organic dye. acs applied materials and interfaces, 6(22); 20225–20233 zhao, j., q.huang, m.liu, y.dai, j.chen, h.huang, y.wen, x. zhu, x. zhang, and y. wei (2017). synthesis of functionalized mgal-layered double hydroxides via modied mussel inspired chemistry and their application in organic dye adsorption. journal of colloid and interface science, 505; 168–177 © 2021 the authors. page 234 of 234 introduction experimental section chemicals and instrumentation preparation of cu/al ldh preparation of cu-al/bc and cu-al/gf selectivity of anionic dye mixtures desorption and regeneration of adsorbent adsorption process results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 3, july 2021 research paper tablet formula optimization from helminthostachys zaylanica extract using a simplex lattice design fitrya1*, najma annuria fithri1, budi untari1, aprililianti1, 1department of pharmacy, universitas sriwijaya, palembang, south sumatera *corresponding author: fitrya@unsri.ac.id abstract helminthostachys zeylanica extract has pharmacological activities such as antioxidant, antiinflamatory, and antihyerucemia. thisextract is nontoxic substance from the acute and subchronic toxicity tests. this extract has a potency to be formulated into tabletdosage forms. this study aims to optimize a tablet formula from helminthostachys zeylanica extract. disintegrant and binderconcentrations were independent variables, while physical properties and dissolution time of the tablets were dependent variables.the tablet was prepared by a wet granulation method. formula was optimized by simplex lattice design. physicochemical propertiesof granule, physical properties and dissolution of tablet were then analyzed with one way anova (p = 0.05). based on granuleanalysis, specification of physicochemical parameters, such as hausner’s ratio, compressibility index, flowability, repose angle, andwater content, met standard british pharmacopeia. in addition, the starch and pva concentrations influenced thickness, weightvariation, hardness, friability, disintegration time and dissolution of the tablets (p <0.05), except for friability (p> 0.05). based on thisstudy, the starch and pva concentrations for the optimum tablet formula were 19.5% and 1.05%, respectively. keywords helmynthostachis zeylanica, tablet, optimization, simplex lattice design received: 9 march 2021, accepted: 11 june 2021 https://doi.org/10.26554/sti.2021.6.3.131-136 1. introduction helminthostachys zeylanica known as tunjuk langit (tl), has active components, such as ugonstilben a-d and avonoids ugonin e-m (chen et al., 2003; fitrya, 2010; wu et al., 2017) pharmacological activities of the extract of tl has been reported as an antioxidant (huang et al., 2003), anti inammatory (huang et al., 2017; su et al., 2016), hepatoprotective (suja et al., 2004), antihyperuricemia (fitrya and muharni, 2014) and antidiabetic (chang et al., 2019; el ridhasya et al., 2020). based on a toxicity test of the extract, it was reported to be safe for consumption (fitrya, 2017). nowadays, the use of herbal medicine is becoming more popular. extract formulations into pharmaceutical dosage forms are increasingly developed for both topical and oral uses. the most popular-oral dosage is a tablet form because it is easy for consumption and is better stability (de souza et al., 2007; nguyen et al., 2013). several studies on tablet formulations of the herbal extracts were reported such as tablets from morus alba extract (son et al., 2018), ginger dry extract (malek et al., 2020); pachyrrhizus erosus extract (kharisma et al.); curcuma longa exctract (ermawati et al., 2017); and phillanthus niruri extract (de souza et al., 2007). the herbal extracts tend to be high hygroscopic because they are composed from carbohydrates as a major component. the hygroscopic properties of the extract inuence the ow properties. furthermore, these ow properties cause tablet compactibility if they are formulated to a tablet dosage form. therefore, the determination of the type and concentration of the excipient will determine the qualityof the tablets (son et al., 2018). in the preliminary study we have prepared three tablet formulations of the tl rhizome ethanol extract using dierent disintegrant and binder combinations, i.e., formula a: starch & polyvinyl alcohol (pva); formula b: avicelrph102 and polyvinyl pirolidone (pvp); and formula c: sodium alginate & methylcellulose. based on physical properties and dissolution of the tablets, formula a had the best physical properties and dissolution(fitrya, 2016). the main function of disintegrant is contrary to binder eciency but the disintegrant and binder are essential components which determine an ability of tablet disintegration. the stronger the binder, the more eective the disintegrant must be for the tablets to release its medicine. disintegrant plays an important role of water absorption into the tablet matrix, so that the tablets turn into granules and subsequentlybecome primaryparticles. the formation of primary https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.3.131-136&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.3.131-136 fitrya et. al. science and technology indonesia, 6 (2021) 131-136 particles increases the dissolution rate and bioavailability of the drug (desai et al., 2016; dilebo and gabriel, 2019). therefore, the type and concentration of disintegrant and binder are important to ensure a good bioavailability of drug (bhowmik et al., 2010). this study aims to determine optimum disintegrant and binder concentration in a tablet formula. optimum concentration was determined by simplex lattice design (sld) using software design expertr8 (dxr8) 2. experimental section 2.1 material the active ingredient was ethanol extract of the tl rhizome. this rhizome was collected from ogan ilir area, south sumatera. all chemicals are in analytical grade. 2.2 methods design of optimum formula tablets were made according to the best formula from previous studies using starch as a disintegrant and pva as a binder (fitrya, 2016). optimization of tablet formula was designed using a simplex lattice design (dxr8 software, usa). the independent variables are the concentration of binder and disintegrant while the dependent variables are the physical properties and dissolution of tablets. the starch is in a range of 5-20% (bhowmik etal.,2010) andpvais less than2%(saxena,2004). therefore, pva is 1% and 2% for low and high levels, respectively. based on the simplex latice design, 8 tablet formulas were produced (table 1). the extract was mixed with lactoce until reaching homogen. the disintegrant, adsorbent, and binder were added sequently. producedgranulesweredriedat40-50◦cuntil constantweight, and they were then sieved with no. 14. the dry granule was added magnesium stearate and talcum as lubricant. the resulting granules were evaluated for their physical properties, such as the hausner’s ratio, compressibility index, owability, angle of repose and water content (ermawati et al., 2017). the granules were evaluated following the british pharmacopoeia, 2008. finally, the granules were pressed into tablets by tabletingmachine (dtr4). anoptimimumformulawasdetermined based on a formula producing tablets with the best physical properties and dissolution. the physicalproperties evaluation of tablets the physical properties of tablet studies included organoleptic, thickness, weight variation, hardness, friability, disintegration time, and dissolution (kharisma et al.; mishra, 2019). the friability of tablet referred to the british pharmacopoeia, 2008 using friability tester (cs-1 friability tester). tablet uniformity and disintegration time were determined referring to indonesian pharmacopeia 4nd by disintegration tester (bj-3 disintegration tester), while tablet hardness was determined referring to the united states pharmacopeia 32nd, 2009 by a hardness tester (yd-1 hardness tester). experiment results were statistically analyzed by spssr21. figure 1. tablet run 1-8 in vitro dissolution study the optimum formula dissolution was tested referring to the british pharmacopoeia, 2008 using the dissolution tester (rc3 dissolution tester) by determining a total phenolic content as a marker. the total phenolic content was measured by the folin-ciocalteu’s method. 3. results and discussion 3.1 granules properties experimental design of tablet formula using dxr8 software was produced eight formulas (f1-f8) showed in table 1. a wet ganulation method was used based on consideration of characteristics of the extract, such as viscousity and hygroscopy. in addition, by the wet granulation method, ow properties and compressibility of powder can be improved so that the powder can be more easily compressed into tablets. quality all of granule formulas, that is determined by repose angle, hausner ratio and compressibility index, can be categorized from good to excellent in their ow properties as presented on table 2 (mishra, 2019). moreover, the plant extracts tend to be more hygroscopic and low owability. these excellentowpropertiesbecomeamainspecicationforweight uniformity during compression of tablets (son et al., 2018). 3.2 physical properties of tablets tablet formulas1–8fromtheexperimentaldesignareshownin figure 1. the physical properties of these tablets are presented in table 3. weight variations of these eight formula tablets were in a range of 0.50–0.52 g. these variations indicated all batches in weight uniformity, and each batch content is uniform. the mathematical models for responses as tablet characteristics from the dxr8 software are presented in table 4. as indicated in table 4, starch and pva concentration inuenced tablet characteristics (except friability) i.e., weight, thickness, hardness, and disintegration time. in the mathematical models, a positive coecient inuenced responses synergistically, while a negative coecient showed an antagonistic eect on the responses (rao et al., 2009). moreover, the starch and pva concentration individually inuenced weight and thickness responses while the interaction between both concentration did not have eects. increase in starch and pva © 2021 the authors. page 132 of 136 fitrya et. al. science and technology indonesia, 6 (2021) 131-136 table 1. experimental design of optimized formula runs concentration (%) extract lactose aerosilr talc mg stearate starch pva (mg) (mg) (%) (%) (%) f1 17.5 1.25 135 260.49 0.5 1 0.5 f2 12.5 1.75 135 282.99 0.5 1 0.5 f3 10 2 135 294.24 0.5 1 0.5 f4 15 1.5 135 271.74 0.5 1 0.5 f5 20 1 135 249.24 0.5 1 0.5 f6 15 1.5 135 271.74 0.5 1 0.5 f7 20 1 135 249.24 0.5 1 0.5 f8 10 2 135 294.24 0.5 1 0.5 table 2. the granules properties evaluation results formula hausner ratio compressibility flowability angle of repose water content (runs) ± sd index (%) ± sd (10 g/s) ± sd (◦) ± sd (%) ± sd 1 1.14 ± 0.06 12.23 ± 4.78 1.62 ± 0.16 28.0 ± 2.92 7.92 ± 3.67 2 1.10 ± 0.00 9.02 ± 0.12 1.97 ± 0.06 26.7 ± 1.05 8.05 ± 1.40 3 1.15 ± 0.01 12.9 ± 0.42 2.20 ± 0.26 30.07 ± 2.29 5.88 ± 1.40 4 1.10 ± 0.03 9.42 ± 2.16 2.20 ± 0.26 29.58 ± 3.48 7.19 ± 0.51 5 1.14 ± 0.02 11.9 ± 1.16 2.30 ± 0.10 31.07 ± 1.89 6.18 ± 1.47 6 1.10 ± 0.03 9.42 ± 2.16 2.20 ± 0.26 29.58 ± 3.48 7.19 ± 0.51 7 1.14 ± 0.02 11.9 ± 1.16 2.30 ± 0.10 31.07 ± 1.89 6.18 ± 1.47 8 1.15 ± 0.01 12.9 ± 0.42 2.20 ± 0.26 30.07 ± 2.29 5.88 ± 1.40 concentration would increase weight of tablets because molecular weights of the starch and pva are 300–1000 g/mol and 20.000–200.000g/mol, respectively(roweetal.,2009). mean while, the dierences in the tablet thickness were due to the dierences in pressure during the pressing process (rao et al., 2009). friability was tested to assess eects of friction and shocks, which may often cause breaking, capping, or cracking tablet (hardenia et al., 2016; zade et al., 2009). according to bp 2008 a good friability value is less than 0.8%, the tablets were therefore indicated agood mechanical resistance. lowfriability indicated that the tablet has resistance to friction and is able to maintain its shape. while the tablet surface has been eroded in high friability (kharisma et al.). furthermore, hardness was tested to describe tablet endurance through good mechanical resistance for packing and distribution. the individual component of the starch and pva and their interactions signicantly increased hardness and disintegration time. on the other hand, factor of disintegrant and binder and interaction of both could insignicantly reduce the friability of tablet. the starch has more eect on tablet hardness compared to pva. the hardness can also be inuenced by a compression force during manufacturing, pressing speed, and a height diameter ratio of the tablets (adeleye et al., 2015). as starch tend to deform, increasing the starch concentration allows blends more compact (bhowmik et al., 2010). in addition, the using more pvacaused an increase in hydroxyl groups to binding the other tablet component. based on response equations in table 4, starch concentration become a dominant factor inuencing hardness. increasing starch, pva, and their interaction accelerated the disintegration time. based on their coecients, pva had the most eect on disintegration time compared to starch and their interaction. during the disintegration process, the capillary bridges were formed causing adjacent particles to attract each other. the disintegration capability must exceed interparticulate forces and destruct the bonds. penetration of liquid into tablet pores is the rst step and often determines the rate of tablet disintegration (markl and zeitler, 2017). increasing starch concentration would also improve a wicking mechanism and deformation recovery, resulting in a faster disintegration time. pva has a high tendency to swell in water and biological liquid (kadajji and betageri, 2011). the hydroxyl groups in the pva molecules which are close each other will interact to form intra and intermolecular hydrogen bonds. this hydrogen bond results in crystal formation. increase in crystallinity in the swelling polymer reduces the disintegration ability (muppalaneni, 2013; markl and zeitler, 2017). 3.3 in vitro dissolution study a drug release prole of tablets in vitro was observed by percentages of the drugrelease for60minutes (de60) aspresented in figure 2. © 2021 the authors. page 133 of 136 fitrya et. al. science and technology indonesia, 6 (2021) 131-136 table 3. the physical properties of tablets batch weight thickness friability hardness disintegration time (g) ± sd (mm) ± sd (%) (n) ± sd (mnt) ± sd 1 0.51 ± 0.01 3.36 ± 0.15 0.3 19.33 ± 3.15 11.79 ± 1.88 2 0.52 ± 0.01 3.32 ± 0.06 0 27.33 ± 1.65 16.47 ± 1.87 3 0.51 ± 0.01 3.56 ± 0.13 0 17.53 ± 3.02 28.67 ± 2.12 4 0.52 ± 0.01 3.48 ± 0.07 0 29.18 ± 2.17 29.16 ± 1.13 5 0.51 ± 0.02 3.41 ± 0.16 0 35.52 ± 4.04 15.65 ± 1.10 6 0.52 ± 0.02 3.48 ± 0.05 0 30.53 ± 3.62 29.24 ± 2.64 7 0.50 ± 0.01 3.36 ± 0.11 0.15 34.52 ± 3.12 15.93 ± 1.24 8 0.51 ± 0.02 3.58 ± 0.10 0 13.92 ± 0.77 30.93 ± 4.23 table 4. mathematical models of responses respons (y) sld actual component equation p valuemodels of respons weight variation y = 0.50 (a) + 0.51(b) + 0.020.05 (a)(b) thickness y = 3.38(a) + 3.57(b) + 1.00(a)(b) + 0 0.70(a)(b)(a-b) 3.96(a)(b)(a-b)2 friability y=0.07(a) + 0.00(b) 1.00(a)(b) + 0.11 1.40(a)(b)(a-b) 3.00(a)(b)(a-b)2 hardness y= 35.02(a) + 15.72(b) + 56.31(a)(b) – 0 94.12(a)(b)(a-b) 153.62(a)(b)(a-b)2 disintegration y= 15.79(a) + 29.80(b) + 25.62(a)(b) + 0time 12.40(a)(b)(a-b) – 287.33(a)(b)(a-b)2 a = starch concentration and b = pva concentration figure 2. dissolution curve of formula 1–8 the mathematical model recommended was quartic with p value less than 0.05 this model indicates that two components (aand b) have a signicant eect on de60 of tablets. the sld actual components are given in equation 1. y = 67.21(a) + 42.65(b) + 46.71(a)(b)˘118.71 (a)(b)(a − b) + 469.11(a)(b)(a − b)2 (1) from eq. 1, starch and pva increase de60 of tablets, and starch has more signicant eects than pva. increasing starch concentration formed capillary pathways that were getting bigger. moreover, the starch became more liquid penetrating into the tablet, and disintegration time of tablet was then faster. in addition, an increase in starch concentration resulted in more disintegrating particles undergoing deformation. increasing the distintegration time accelerated the dissolution rate of the tablet (kumar et al., 2016). 3.4 optimum formula optimum formula was determined based on dependent variable responses. responses priority are from 1 (low) to 5 (high). the weight, thickness, friability, and disintegration time of tablets responses were selected in a minimum priority, while the hardness response was selected for level 3 (medium). the less weight and thickness tablet was, the easier it swallowed. if the tablet was too hard, tablet disintegration was postponed and dissolution was bad. meanwhile, less hard tablets would be easier to break down them for packing and distributing. the faster disintegration time of tablets was, the better the dissolution of tablets would be. the tablet dissolution is selected in a maximum priority, because the dissolution prole is important parameter ensuring a drug bioavailability. the faster dissolution rate would result in better drug absorptions. © 2021 the authors. page 134 of 136 fitrya et. al. science and technology indonesia, 6 (2021) 131-136 dxr8 analysis obtained three proposional combinations of the starch and pva, and the largest desirability value (0.777) was selected. this optimum composition consisted of 19.5% starch and 1.05% pva. if the starch concentration was under this optimum level, capilariy pathways would be not formed. in contrast, if the concentration was too much, the tablet compressibility became too bad (bhowmik et al., 2010). disintegration time of tablet was long when the pva concentration was 2%. the pva has many hydroxyl groups in its structure, so that it has a capabilityas binder. therefore, higher concentration of pva resulted in more hydroxyl groups interacting with the extract components. the pva binded either the extract or other components of tablet by hydrogen bonds, dipole-dipole interactions, and van der waals’s bonds. 4. conclusions the starch and pva concentration signicantly inuenced the tablet characteristics. based on characteristics and dissolution analysis, the optimum concentration of the starch and pva on tablet formula are 19.5% and 1.05%, respectively. in order to use dryextracts formakinga tablet, we suggest to reduce extract moisture and to improve ow properties of the granules. 5. acknowledgement we gratefully acknowledge the support universitas sriwijaya, sponsored by “penelitian hibah bersaing,” ministry of research technology and higher education, indonesia. references adeleye, o.a., m.n.femi-oyewo, andm.a.odeniyi (2015). eect of compression pressure on mechanical and release properties of tramadol matrix tablets. current issues in pharmacy and medical sciences, 28(2); 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1–10 zade, p., p. kawtikwar, and d. sakarkar (2009). formulation, evaluation and optimization of fast dissolving tablet containing tizanidine hydrochloride. int j pharm tech res, 1(1); 34–42 © 2021 the authors. page 136 of 136 introduction experimental section material methods results and discussion granules properties physical properties of tablets in vitro dissolution study optimum formula conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper validation of mercury speciation analysis in river around artisanal small-scale gold mining area in west nusa tenggara, indonesia dhony hermanto1*, nurul ismillayli1, nindi herdiyanti1, siti raudhatul kamali1,2, soraya aulia3 1department of chemistry, faculty of mathematics and natural sciences, university of mataram, mataram, 83125, indonesia2department of applied chemistry, chaoyang university of technology, wufeng, 41349, republic of china3laboratory center of health testing and calibration, west nusa tenggara provincial health office, mataram, 83121, indonesia *corresponding author: dhony.hermanto@unram.ac.id abstracta method for determining mercury concentration using a mercury analyzer in a river water sample was validated according toiso/iec 17025. analytical performance including linear range, limit of detection, precision and accuracy were evaluated. mercuryspeciation profile was obtained from pelangan river at three areas within dusun rambut petung, an area with the highest amount ofartisanal small-scale gold mining (asgm) in lombok, west nusa tenggara. then, their concentration in each species was measuredusing sequential extraction. good curve linearity was obtained in the concentration range of 0.1-5.0 µg/l and the limit of detectionwas 0.014 µg/l. the developed method has good precision and accuracy with a rsd value <10% and a recovery of 94.16-101.91%.the detected fraction of mercury in the pelangan river is organomercury, elemental mercury, and sulfide-bound species with eachconcentration of 0.732±0.032; 0.350±0.027; and 0.850±0.027 µg/l, respectively. the measurement results showed conformitywith the reference method using cv-aas. therefore, this method can be applied to determine mercury levels in water for monitoringenvironmental quality. keywordsvalidation, mercury analyzer, mercury speciation, the pelangan river, rambut petung district received: 24 august 2021, accepted: 12 july 2022 https://doi.org/10.26554/sti.2022.7.3.379-384 1. introduction gold as a mineral resource with a very high economic value is available in plentiful supply in sekotong district, lombok island, indonesia. it has led to rampant mining activities, especially asgm which began in mid-2008 until now (krisnayanti et al., 2016). asgm is carried out by people in the sekotong area using the amalgamation method, which is a traditional method of separating gold from the rock using mercury, a very toxic and dangerous chemical (brooks et al., 2017; spiegel et al., 2018). it is estimated that between 410 and 1400 tonnes of mercury are emitted worldwide through asgm each year, equivalent to 37% of global mercury emissions from anthropogenic source (esdaile and chalker, 2018; seccatore et al., 2014). hence, monitoring mercury from gold mining waste is an important issue that needs serious handling. mercury is a pollutant that has received the most attention becauseof itshigh toxicityandpersistenceandaccumulativebehavior in the environment. considering thatmercuryisvolatile in metalic hg0 form, can transport through the atmosphere at considerable distances. mercury also exist as organo-hg that can bioaccumulate in organisms (unep, 2013). mercury in the environment exists in dierent molecular forms according to specic biogeochemical transformations and ecotoxicity. inorganic ionic mercury (hg2+) is a common form/species found in water samples (hermanto et al., 2019; hermanto et al., 2022). particular attention is given to mercury which undergoes a natural transformation called organomercurycompounds (hrubaru et al., 2018), including the in-situ formation of methylmercury (mehg) and dimethylmercury (me2hg). although it usually represents a small portion of total mercury (hgtot) in aquatic environments, methylmercury is highly toxic due to its tendency to bioaccumulate and biomagnify in the aquatic food chains (živković et al., 2017; omwoma et al., 2017). determination of hgtot concentration is not sucient to understand its presence in the environment (spyropoulou et al., 2018), each species has dierent mobility and aect its availability, as well as its toxicity. according to the international union of pure and applied chemistry (iupac), speciation analysis is an analytical activity for the identication and measurement of one or several individual chemical forms of an element including mercury (stoichev et al., 2006; https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.379-384&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.379-384 hermanto et. al. science and technology indonesia, 7 (2022) 379-384 templeton et al., 2000). validation of analytical methods as a crucial step of quality assurance is needed to obtain reliable results in quantitative analysis (eka et al., 2012). based on iso/iec (2017), the validation of the analytical method intends to assure that the method meets the acceptance criteria. reference method for the determination of mercury in the water sample by cold vapor-atomic absorption spectrometry (cv-aas), is recommended by (epa, 1994; kallithrakas-kontos and foteinis, 2016). until now, the application of a mercury analyzer for the species mercury quantication in aquatic samples has not been reported. the pelangan river is one of the rivers that ow in sekotong used for irrigation and it passes dusun rambut petung. aquatic samples were obtained from the pelangan river in dusun rambut petung sekotong-lombok. this area was chosen because it is the most plentiful area of asgm, with more than 900 ball mills for crushing gold ores. hence, it is essential to assure its quality control including the level of mercury. developing and validating a mercury analyzer for the quantication of species mercury in pelangan river, dusun rambut petung sekotong-lombok island, was conducted in this study. 2. experimental section 2.1 materials and instrument the sample was pelangan river water that was collected based on the sampling technique criteria. mercury standard solution (1000 mg/l) was purchased from sigma aldrich (steinheim, switzerland). the rest of the reagent was obtained from merck (darmstadt, germany) with a pro analyst grade classication. distilled and deionized water were used as solvents. all glassware used in this study was soaked in a detergent solution, then rinsed with distilled water. mercury instrument® analytik jena mercur duo and mercur duo plus (jena, germany) based on atomic absorption without enrichment was used for mercury determination. the instrument was operated via winaas for mercur. the instrument was equipped with hg low-pressure lamp uvu5 with beaker electrode, detector photomultiplier (pmt) 1p28 with 9-stage. the measurement wavelength was 253.7 nm, the airow was set at 10 l/h and the sensitivity of the analytical balance was 0.1 mg. 2.2 sample station the study was located in the pelangan river, dusun rambut petung, in sekotong district, lombok island in the latitude between 8°48’37" to 8°49’4"s and longitude between 115°56’40" to 115°57’36"e. the river that crosses this village has a length of about 2.2 km and a width of 3.5 m with an average depth of the river is 1.5 m. water samples were collected from three sampling stations. the stations are selected depending on the estimated water quality and pollution levels when observing the study area. station 1 was in the direction of the upstream river, station 2 was in the mining waste disposal location and station 3 is in the downstream direction. water samples were collected from 3 sampling stations during the period in april 2021 (in the rainy season with a river ow speed of 10 ms−1). 2.3 sample collection for sampling, 500 ml of water sample was placed in a plastic bottle with a double plug from each sampling station. before taking samples, the bottles were cleaned and washed with a detergent solution then rinsed with 5% hno3 and left overnight. the bottles were nally rinsed with deionized water and dried. at each sampling station, sample bottles were rinsed at least three times before sampling. the prepared sample bottles were immersed about 10 cm below the surface of the water. the sample was acidied with 10% hno3, then the bottles were carefully sealed, marked with their respective identication numbers, placed in an ice bath, and taken to the laboratory. samples were ltered through a 0.45 `m micropore membrane lter and frozen at 4°c for preservation and avoiding further contamination until the analysis process was carried out. 2.4 river water analysis the standard curve for mercury solution was made in various mercuryconcentration, namely0.1; 0.5; 1.0; 2.5and5.0 `g/l. a blank solution was prepared by mixing the standard reagent for 100 ml of sample (consisting of 1000 `l kbr-kbro3 and 50 `l hydroxylamine hydrochloride 12%) and dd water up to a volume of 100 ml. variation of mercury concentration was obtained by mixing some mercury stock solutions with standard reagent and diluted with dd water according to the required concentration. determination of the total mercury concentration in river water samples was carried out according to the research method conducted by gill and bruland (1990), which was obtained by mixing 50 ml of the sample with 10 mlof 4% nabh4 solution (w/v) in 0.15 n naoh, then adding a standard reagent solution. all solutions were measured for absorbance with a mercury analyzer at a wavelength of 253.7 nm and the repetition was carried out 3 times. 2.5 validation method the validation method was carried out by assessing several analytical numbers based on the international conventions on the analytical method (magnusson, 2014; ich, 1994), such as linearity and dynamic range, sensitivity expressed by detection limits (lod), and quantitation limits (loq), precision, accuracy and performance tests compared to reference methods recommended by epa methods 245.1 for the determination of mercury in the water sample, namely cv-aas (epa, 1994; kallithrakas-kontos and foteinis, 2016). the performance test was carried out for the determination of hgtot in aquatic samples. 2.6 mercury speciation determination of the concentration of hg metal speciation using a stepwise extraction method was conducted based on the research method by boszke et al. (2008). before the measurement, standard reagent and solution were added to each © 2022 the authors. page 380 of 384 hermanto et. al. science and technology indonesia, 7 (2022) 379-384 fraction and the absorbance of each fraction was measured using a mercury analyzer at a wavelength of 253.7 nm. fraction 1 was the organomercury fraction that was obtained by adding 50 ml of river water sample with 30 ml chcl3 and shaking for 3 min. furthermore, the sample mixture was centrifuged at 3000 rpm for 15 min and the results were decanted. the organic phase was extracted again using 10 ml of 0.01 m na2s2o3 for 3 min, then it was separated. the upper phase (sodium thiosulfate) was added with the measuring agent. fraction 2 was water-soluble. the water phase from fraction 1 was ltered with a lter membrane then put in a test tube and added with the measuring agent. fraction 3 was acid-soluble. it was obtained by adding 50 ml of river water sample with 25 ml of 0.5 m hcl and centrifuging at 3000 rpm for 15 min. the result was ltered with a lter membrane then put into a test tube and the measuring agent was added. fraction 4 is the associated fraction in humic material, this was obtained by adding 50 ml of river water sample with 30 ml of 0.2 m naoh and centrifuging at 3000 rpm for 15 min. the result was ltered with a lter membrane then put into a test tube and the measuring agent was added. fraction 5 was an elemental mercury fraction that was obtained by digesting 50 ml of river water sample with 12 ml of 37% hcl and 4 ml of 65% hno3. the mixture was put into a test tube and the measuring agent was added. fraction 6 was the residual fraction, it was obtained by heating 50 ml of river water at 150°c for 30 min and digested using 12 ml of 37% hcl and 4 ml of 65% hno3. the mixture was put into a test tube and the measuring agent was added. 3. results and discussion to evaluate the validity of the proposed method, the analytical performance characteristics for the determination of mercury in aqueous samples were estimated. some of the analytical performance characteristics were determined by a calibration curve, as shown in figure 1. the rst evaluation of the analytical performance characteristic is the linear range. the linearity of the response was studied using a calibration curve for a standard solution of mercury by plotting the absorbance against the mercury concentration. figure 1 shows a plot of the calibration curve between mercury concentration and absorbance measured at a wavelength of 253.7 nm. good curve linearity is obtained, with a correlation coecient, r2=0.9998(r»1) in the mercury concentration range between 0.0 to 5.0 `g/l. according to magnusson (2014), the analytical characteristic is linear over a given concentration range if r2 obtained is higher than 0.995. the lod is the lowest detectable concentration of the analyte and is reliably distinguished from zero concentration, it should not be measured. while, the loq is the lowest concentration of analyte that can be quantized with an acceptable level of precision (gonzález and herrador, 2007). in determining lod and loq, the sample blank solution was measured. lod and loq were calculated as 3×3stdev/b and 10stdev/b, respectively, where stdev is the standard figure 1. the calibration plot of hg masurement deviation of the analyte response and b is the slope of the calibration curve (figure 1) (magnusson, 2014). in this proposed method, the lod and loq are 0.014 g/l and 0.016 g/l, respectively, found to be more sensitive than conventional atomic absorption spectroscopy for the determination of mercury with an lod of 0.12 g/l (hartwig et al., 2019). in this study, precision was measured as the relative standard deviation (rsd) of mercury concentration. the accuracy of the mercury analysis shows that the response of the mercury standard solution is always reproducible, including errors due to the operating system, but not errors due to handling and sample preparation (ertas and tezel, 2004). to assess the accuracy of the analytical method, measurements were made in a repeatable condition. in figure 1, it can be seen that the rsd of mercury analysis is less than 10%. the maximum acceptable rsd value is 32% (for analyte concentration <10.0 `g/l), hence the precision of the proposed method is excellent (gonzález and herrador, 2007). table 1. accuracy studies data for mercury analyzer spiked analyte concentration (`g/l) found analyte concentration (`g/l) stdev rsd (%) recovery (%) 2.0 2.01 0.03 1.49 95.62 3.0 2.83 0.05 1.77 94.16 4.0 3.95 0.03 0.76 101.9 recovery study was carried out to conrm deciency or loss of analytes or contamination during sample preparations and matrix disturbances during measurement. this parameter is used to evaluate the accuracy of the analytical method (ertas and tezel, 2004). recovery is determined by the spiking technique, the concentration of the known mercury solution is added to the sample, then the resulting spike is measured, calculated, and compared with the added mercury solution (concentration is known). all analytical steps were carried out in three replications with three dierent levels of mercuryconcentration. the recovery values are in the range 94.16-101.91% © 2022 the authors. page 381 of 384 hermanto et. al. science and technology indonesia, 7 (2022) 379-384 (table1), is acceptablebecause it is in therangeof60-115%(for analyte concentration <10.0 `g/l) (taverniers et al., 2004). hence, the method developed is accurate for calculating mercury samples in the aqueous system. the performance of the mercury analyzer was evaluated in the analysis of aquatic samples. the standard addition method was used by spiking dierent amounts of mercury into the sample. the results of the determination are summarized in table 2. statistical analysis using anova showed that each station has real dierent results, fstat > fcrit (fstat=41.421, fcrit=9.552), pvalue<0.05 (0.006), means that h0 is rejected. while, statistical analysis for mercury analyser and cv-aas comparisonobtainedthatfstat <fcrit (fstat=0.087,fcrit=7.708), pvalue>0.05, means that h0 is accepted (there is no signicant dierent between mercury analyzer and cv-aas measurement results). the results indicated that the developed mercury analyzer has very good characteristics for the determination of mercury in the aquatic sample. the results shown in table 2 were based on the reference method using cv-aas. determination of the concentration of various types of mercury species and their availability in river water (in station 2, mining waste disposal site) can be done simply by sequential extraction. it can provide detailed information about the origin, stages of events, possible biological and physicochemical preparations, movement and displacement of metals as well as partition metal particulates in the environment (boszke et al., 2008). in this study, there were six stages of sequential extraction to determine the various fractions of mercury in various types of speciation including the organomercury fraction, the water-soluble fraction, the acid-soluble fraction, the mercury fraction bound to the humus material, the elemental mercury fraction, and the mercury fraction bound to suldes. result for determination of mercury speciation in the pelangan river, rambut petung, sekotong, lombok island as shown in figure 2. figure 2. mercury speciation in the pelangan river, rambut petung sekotong in the organomercury fraction, mercury compounds are bonded directly to the carbon atoms of organic matter (e.g. ch3hg). this species has a higher toxicity than inorganic mercury species and is the most easily displaced so that it is easier to accumulate in living things than other heavy metals. its ability in forming strong binding with sulfhydryl proteins, encourage this fraction accumulated in the tissue of a living organism. in the extraction stage, chloroform, an organic solvent, and nonpolar were used to extract the organomercury fraction. the selective method of organomercury extraction was the pre-concentration process, where the obtained extract in organic solvents was extracted again using sodium thiosulfate to obtain the concentration of this species (boszke et al., 2008). methylmercury, methyl group bonded to mercury(ii), is one of the organomercury may undergo complexation reaction with thiosulphate ion (lu et al., 2014), according to the chemical reaction equation 1. h3c − hg+ + 2(s2o3)2− → hg(s2o3)22− + −ch3 (1) sodium thiosulfate is an excellent chelating ligand to bind mercury, where thiosulfate has a sulde group that has a tends to bind strongly to mercury. the contribution of organomercury species to the total mercury concentration in this study showed a level of 0.732±0.032 `g/l, as shown in figure 2. the contribution value of this species was the second-highest in mercury speciation compared to other fractions. due to its toxicity and bioaccumulation in living things, serious attention is needed on this issue. the water-soluble fraction of mercury is a species that is easily moved due to its solubility in water. usually, mercury is not a water-soluble ionic species but it is a species bound to organic matter (without carbon-hg bonds) or suspended mineral particles. the contribution of water-soluble mercury species to the total concentration of mercury in this study is not detected, as shown in figure 2. the undetectable mercury metal was probably caused by slow river ow that cause a methylation process, in which mercury(ii) methylation process was caused by sulfate-reducing bacteria under anoxic conditions. in addition, mercury(ii) could be bound to hydroxides, chlorides, and suldes found in river water, then coagulated and was precipitated. the contribution value of this species showed that it has high mobility so that it is not detected in the water phase (balogh et al., 2008). acid-soluble fraction is dened as mercury species released under acidic conditions and sensitive to ph changes of river water. commonly, mercury is bound to iron monosulde, iron and manganese hydroxide, and carbonate. these compounds can include species that are bound to organic matter and adsorbed on mineral surfaces (boszke et al., 2008). as shown in figure 2, the contribution of this mercury species in this study is not detected, which indicated that this species was not found in the dissolved water phase or its concentration is lower than lod (0.014 `g/l). © 2022 the authors. page 382 of 384 hermanto et. al. science and technology indonesia, 7 (2022) 379-384 table 2. determination of mercury in aquatic samples using mercury analyzer and cv-aas sample found mercury concentration (`g/l) relative error by mercury analyzer by cv-aas (%) station 1 (8°48’37"s,115°56’40e) 0.95 0.83 0.126 station 2 (8°48’50"s,115°56’48e) 1.571 1.452 0.082 station 3 (8°49’4"s,115°57’36e) 1.28 1.29 0.008 notes: average triplicate of measurements the fraction associated with humus material is in the form of organic material/humus substances such as humin, humus acid, and fulvic acid which are important components of sediment and soil. humic acid does not dissolve at acidic ph but dissolves at alkaline ph conditions, fulvic acid dissolves in water at all ph conditions, while humin does not dissolve under acidic or alkaline conditions (sparks, 2003). under certain conditions, the humus substance plays a role in metal bonds. organic mercury is mercury in the form of a complex mercury(ii) with ligands such as humus, fulvic acid, amino acids (without hg-carbon bonds). mercury is bound to organic material with the thiol (r-sh), disulde (r-ssr), or disulfane (r-ssh) functional groups (boszke et al., 2008). on the water surface, the humic content is expressed as dissolved organic carbon (doc). humic acid does not dissolve at ph<2 but it dissolves in alkaline conditions so that in this fraction an alkaline process is carried out by adding naoh to determine the hg bound to humic acid. in general, the organic ligands in humus material in the form of humic acid and fulvic acid are slightly acidic because the metal easily binds to the acidic humus material. the contribution of mercury species bound to humus material to the total concentration of mercury in this study is not detected (lod of 0.014 `g/l), as shown in figure 2. it was possible that the humus material bind to other organic matter or clay then settles on the bottom of the river so that it was not found in the sample. in the elemental fraction, mercury is a species of mercury in the form of pure metal mercury (hg) which is easily volatile. the use of aqua regia (a mixture of hno3 and hcl) as a strong oxidizercausesmercurytobeoxidized tohg2+ according to the reaction equation 2. the contribution of elemental mercury species to the total mercury concentration in this study showed levels of 0.350±0.027 `g/l, as shown in figure 2. hg+hno3 +3hcl → hg2+ +cl2 +nocl+2h2o (2) the fraction bound to the sulde is a non-mobile fraction. in this fraction, the sample was digested by heating to remove disturbing substances from other organic materials. then it is oxidized using aqua regia to obtain hgcl2 (mikac et al., 2002) according to equations 3 and 4. hno3 + 3hcl → nocl + cl2 + 2h2o (3) hgs + cl2 → hgcl2 + s (4) the contribution of sulde-bound species to the total concentrationofmercuryin this studyshowedlevelsof0.850±0.027 `g/l, as shown in figure 2. the nature of mercury sulde which is stable and dicult to dissolve in water also allows the greatest concentration value obtained compared to metal mercury and organomercury. the total mercury concentration calculated as the sum of the mercury concentration in individual fractions by stepwise extraction obtained in this study was 1.57±0.014 `g/l. 4. conclusion amethod validation on mercuryanalyzer formercurydetermination followed by sequential extraction for mercury speciation was conducted in pelangan river, rambut petung district. the result showed low lod of 0.014 `g/l, good linear range concentration of 0.0-5.0 `g/l, good precision, and accuracy with rsd <10%, and recovery of 94.6-101.91%. there were three forms of mercury detected, namely organomercury of 0.732±0.032 `g/l, elemental mercury of 0.350±0.027 `g/l, and sulde-bound mercury of 0.850±0.027 `g/l. the agreement of measurement result between the developed method and cv-aas as a reference method indicated that this method can be used for mercury determination. 5. acknowledgment this research did not receive any specic grant from funding agencies in the public, commercial, or not-for-prot sectors. references balogh, s. j., e. b. swain, and y. h. nollet (2008). characteristics of mercury speciation in minnesota rivers and streams. environmental pollution, 154(1); 3–11 boszke, l., a. kowalski, a. astel, a. barański, b. gworek, and j. siepak (2008). mercury mobility and bioavailability in soil from contaminated area. environmental geology, 55(5); 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(2013). global mercury assessment 2013: sources, emissions, releases and environmental transport. unep chemicals branch, geneva, switzerland živković, i., j. kotnik, m. šolić, and m. horvat (2017). the abundance, distribution and speciation of mercury in waters and sediments of the adriatic sea–a review. acta adriatica: internationaljournal of marine sciences, 58(1); 165–186 © 2022 the authors. page 384 of 384 introduction experimental section materials and instrument sample station sample collection river water analysis validation method mercury speciation results and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 4, october 2018 research paper potential of anabaena azollae extract as antimicrobial agent for paddy crop disease nuni gofar1*, andi diana2, eka setianingsih2 1department of soil science, faculty of agriculture, sriwijaya university, indonesia 2department of agroecotechnology, faculty of agriculture, sriwijaya university, indonesia *corresponding author: nigofar@unsri.ac.id abstract the research objective was to test antimicrobial activity from compound produced by a. azollae which symbiosis with azolla sp. toward microbial test of x. oryzae and pyricularia oryzae as cause of disease on paddy crop. sampling of azolla which symbiosis with a. azollae was done in azolla cultivation pond at faculty of agriculture, sriwijaya university. the available azolla was consisted of two types, i.e. azolla pinnata and azolla mycrophiylla. the extraction of a. azollae from azolla leaves was done by method of ultrasound assisted extraction (uae) using ethyl ester solvent and maseration method using methanol solvent. test media for bacteria and fungus respectively are mueller hilton agar (mha) and sabouraud dextrose agar (sda). the diameter of produced clear zone is an indication of extract’s inhibitory power toward bacteria or fungus. the different of inhibitory zone diameter is compared by using t-test. analysis of active compounds on anabaena azollae extract was done by using hplc. ethyl acetate or methanol extract of a. azollae which symbiosis with a. pinnata or a. microphylla was capable to inhibit the growth of x. oryzae bacterium and p. oryzae fungus. the dominant compounds containing within extract with probability more than 60% and area of more than 10% are consisted of phytol, hexadecanoate acid and 2-(tert-butyl)-4,6-dimethyl phenol. keywords anabaena azolae, azolla microphylla, azolla pinnata, antimicrobe, rice crop received: 14 september 2018, accepted: 16 october 2018 https://doi.org/10.26554/sti.2018.3.4.183-188 1. introduction rice (oryza sativa l.) is the main food commodity in indonesia because the staple food for most of indonesia population is rice. the blast disease caused by pyriculari aoryzae cav. fungus and leaf blight disease caused by xanthomonas oryzae bacterium are important diseases that attack paddy crop. these diseases strike during wet season or humid dry season, especially on constantly �ooding paddy �eld. azolla is water fern plant that frequently found in paddy �eld area and it symbiosis with anabaena azollae that capable to �x n2 and subsequently convert n2 into nitrogen available for crop (muniappan et al., 2016). in addition to contribute nitrogen, a. azollae also produce plant growth hormone and antimicrobia compound (renuka et al., 2018). sianobakter is a source of several compound having antimicrobial activity such as alkaloid, aromatic compound, depipeptide cyclic, peptide cyclic, undecapeptides cyclic, siclopane, extracellulair pigment, lipid acid, linear peptide, lipopeptide, nucleoside, phenol, macrolide, polyketides, polyphenyl ethers, por�noide and terpenoid so that its extract can be used as antimicrobia (swain et al., 2017; salman and m.m, 2016). these bioactive compounds can inhibit the growth of soil induced pathogen bacteria such as x. oryzae bacterium (abraham et al., 2015) and fungi such as p. oryzae that cause blast disease on rice crop (blahova et al., 2013). this research will conduct test in term of antibacterial and antifungal activities from compound produced by a. azollae which symbiosis with azolla sp. on x. oryzae and p. oryzae that frequently cause disease on rice crop. it is expected that results of this research will provide an alternative biological control for blast and leaf blight diseases on rice crop by using azolla sp. as well as n2 contributor for crop. 2. experimental section this research was conducted from november 2017 to april 2018. sampling of azolla which symbiosis with a. azollae was taken from azolla cultivation pond at faculty of agriculture, sriwijaya university. there are two types of azolla, i.e. azolla pinnata and azolla mycrophiylla. extraction of a. azollae from leaves of azolla pinnata and azolla mycrophiylla was done by using ultrasound asisted extraction (uae) with ethyl ester solvent and maseration method with methanol solvent. rejuvenation of x. oryzae bacterium and p. oryzae fungus was done by using tilt agar medium. analysis of active compounds from https://doi.org/10.26554/sti.2018.3.4.183-188 gofar et. al. science and technology indonesia, 3 (2018) 183-188 extraction yield was done by using hplc. 2.1 extraction of anabaena azollae azolla that had been air dried subsequently is blended to produce powder. in maseration method, 300 ml of methanol solvent is added into erlenmeyer containing 50 g dry biomass of azolla. this mixture is incubated for 7 days until the solvent’s color change into dark green. after 7 days, supernatan is collected and dried by using rotatory evapourator. in ultrasound asisted extraction method, 40 ml ethyl acetate solvent is added into erlenmeyer containing 32 g dry biomass of azolla. this mixture is sonicated for 5 minutes, then it is shaked for 15 minutes by using shaker and subsequently it is centrifused at speed of 4000 rpm for 10 minutes. supernatan is separated and collected within erlenmeyer. biomass within pellete is added again with 40 ml ethyl acetate solvent. the extraction steps are repeated several times until all metabolites in biomass had been extracted which indicated by the change of cell biomass color into white color. the collected supernatan is subsequently dried by using rotatory evaporator. 2.2 preparation of bacteria and fungi pure isolates of x. oryzae bacterium and p. oryzae fungus are cultured on tilt agar media by taking colonies from stock of bacterium or fungus by using ose needle and it was scratched on tilt agar media. tilt agar media is incubated at 37°c for 24 hours. subsequently, colonies of bacterium or fungus from tilt agar media are taken by using sterile ose needle and each colony is put into test tube containing 10 ml nutient broth (nb) media. 2.3 preparation of test media test media for bacterium used mueller hilton agar (mha) media with composition as follows: 6% peptone, 17.5% casein, 1.5% starch and 10% agar. twenty �ve grams (25g) of mha media is dissolved in 1000 ml aquadest and sterilized using autoclave at 121°c for 15 minutes. test media for fungus used sabouraud dextrose agar (sda) media with composition as follows: 10 g mycological peptone, 40 g glucose 40 g and 15 g agar. sda media with magnitude of 6.5 g is dissolved with 100 ml aquadest within erlenmeyer and subsequently put on hot plate stirrer to homogenize the solution in order to produce clear solution. media is sterilized in autoclave at temperature of 121°c for 20 minutes. 2.4 test of antibacterial and antifungal activities test of antibacterial and antifungal capabilities was done by using disk paper di�usion method. sterile media of mha and sda are respectively poured into petri dish with thickness of ± 0,5 cm and waited until condense at room’s temperature. suspension of bacterium and fungus respectively with magnitude of 0.1 ml are innoculated using spread plate technique in surface of mha media for bacterium and in surface of sda media for fungus. disk from sterile �lter paper with diameter of 5 mm is saturated with ethyl acetate or methanol extract of a. azollae which life within leaves of a. pinnata and a. mycrophylla. filter paper is put in center of agar surface that had been innoculated with bacterium or fungus, then it is covered and put in upside down position within incubator at temperature of 37°c for 24 hours. diameter of produced clear zone is an indication of extract’s inhibitory power toward bacterium or fungus. inhibitory zone diameter is measured by using vernier caliper. the di�erent of produced inhibitory zone diameter are compared by using t-test. analysis of active compounds from ectraction yield was done by using hplc. 3. results and discussion 3.1 test of antibacterial and antifungal activities figure 1 showed the development of growth inhibitory zone for bacterium or fungus by antimicrobial compounds from ethyl acetate or methanol extract of a. azollae which life within leaves of a. pinnata and a. mycrophylla. an extract has potential as antimicrobia if it produces microbial growth inhibitory zone during the test. the magnitude of produced inhibitory zone is a�ected by antimicrobal compound activity on this extract. salman and m.m (2016) showed that a. azollae can produce toxic compound as antibacterial agents such as alkaloid, neurotoxins and anatoxin. rossana et al. (2006) had reported that antifungal compound produced by a. azollae which life in leave tissue of azolla sp. are phenol, �avonoid, alkaloid, terpenoid, glycoside and saponin. alkaloid compound has inhibitory mechanisms by disturbing peptidoglycan constituent components within cells so that cell wall layers are not fully developed resulting in death of cells (juliantina, 2008). gunawan (2009) had stated that base group containing nitrogen which is available within alkaloid compound reacts with amino acids that compile cell wall and dna of bacterium and fungus. this reaction results in the change of structure and arrangement of amino acids which in turn produce the change of genetic equilibrium in dna chains and damage which promote lysis and death of cells on bacterium. the capability di�erences of ethyl acetate or methanol extract of a. azollae from leaves of a. microphylla and a. pinnata in inhibiting the growth of x. oryzae bacterium and p. oryzae fungus is shown in table 1. tabel 1 showed capability e�ect of a. azolae extract from leaves of a. microphylla and a. pinnata on activitities of x. orizae bacterium and p. oryzae fungus. there was signi�cant di�erent between inhibitory zone diameter of bacterial activity by a. azollae extract from leaves of a. microphylla and a. pinnata using the same solvent, either ethyl acetate or methanol. however, there was no signi�cant di�erent between inhibitory zone diameter of p. oryzae fungus activity by a. azollae extract from leaves of a. microphylla and a. pinnata using the same solvent, either ethyl acetate or methanol. tabel 2 showed test results of capability di�erences of a. azollae extract from leaves of a. microphylla and a. pinnata using di�erent solvents toward x. oryzae bacterium and p. oryzae fungus activities. there was signi�cant di�erent between inhibitory zone diameter toward x.oryzae bacterium and p.oryzae © 2018 the authors. page 184 of 188 gofar et. al. science and technology indonesia, 3 (2018) 183-188 figure 1. development of growth inhibitory zone for x. oryzae bacterium or p. oryzae fungus on agar media table 1. capability di�erence of a. azolae extract from a. microphylla and a. pinnata leaves with the same solvent extraction source of a. azollae solvent inhibitory zone diameter (mm) t-calculated t-table 0.05 on activity of x.oryzae bacterium azolla microphylla ethyl acetate 13 3.45* 2.13 azolla pinnata ethyl acetate 15 azolla microphylla methanol 10 2.59* 2.13azolla pinnata methanol 11.5 on activity of p. oryzae fungus azolla microphylla ethyl acetate 16.25 046tn 2.78 azolla pinnata ethyl acetate 15.58 azolla microphylla methanol 22.25 235tn 2.78azolla pinnata methanol 21.33 © 2018 the authors. page 185 of 188 gofar et. al. science and technology indonesia, 3 (2018) 183-188 figure 2. chemical structures for three compounds within a. azollae extracted from a. pinnata and a. microphylla leaves fungus activities due to treatment of a. azollae extract from leaves of a. microphylla and a. pinnata using di�erent solvent. table 2 showed that four a. azollae extracts had capability in inhibiting the growth of bacterium and fungus. this in accordance to the study results by nabakishore et al. (2015) which showed that extract from a. azollae can inhibit the growth of staphylococcus aureus. a. azollae extract with methanol solvent had lower antibacterial activity than that of using ethyl acetate solvent. this in accordance to the study results by moshi and moshi and mbwambo (2005) which showed that semi polar extract (ethyl acetate) can inhibit e. coli and b. anthracic bacteria with higher inhibitory diameter than that of polar extract (methanol). on the other hand, antifungal activity from extract with methanol solvent was higher than that of using ethyl acetate solvent. methanol that has high polarity is capable to dissolve most of compounds having antifungal property. solvent with low polarity such as ethyl acetate draws antifungal active extract in less quantity than that of ethanol and methanol mixture or methanol alone (ismail et al., 2004). 3.2 the compounds available in a. azolae extract factors which cause di�erences in pathogen inhibitory power are variation and concentration of secondary metabolites contains within extract and the produced fraction. table 3 showed compounds available in a. azolae extract which life within leaves of a. pinnata and a. mycrophylla using ethyl acetate and methanol solvents. widiana (2012) had reported that one of factors that a�ect antimicrobia in inhibiting microbia growth is concentration of antimicrobial substance. the higher the concentration of extract containing antibacteria, the faster the killing process of pathogen. microorganisms have di�erent tenacity to antimicrobia. the higher the number of microbial cells, the longer the treatment time required to kill all microbia. table 3 showed that dominant compounds within a. azollae extract with probability higher than 60 % and area of more than 10 % are consisted of phytol, hexadecanoic acid and 2-(tertbutyl)-4,6-dimethyl phenol. figure 2 showed that chemical structures for three compounds in table 3. in accordance to the published papers by rossana et al. (2006); salman and m.m (2016); swain et al. (2017), the above compounds (hexadecanoat acid, phytol, and phenol) had antimcrobial activity. further research is needed to determine the possibility of compounds that contains in a. azollae extract can be applied as biocide. 4. conclusions ethyl acetate or methanol extract of a. azollae which symbiosis with a. pinnata or a. microphylla was capable to inhibit the growth of x. oryzae bacterium and p. oryzae fungus. the dominant compounds containing in extract of a. azollae with probability higher than 60 % and area of more than 10 % are consisted of phytol, hexadecanoat acid and 2-(tert-butyl)-4,6-dimethyl phenol. 5. acknowledgement this research is part of profession grant research with title of application of functional microbia for food and organic feed which was funded through pnpb unsri for �scal year of 2018. references abraham, g., r. yadav, , and g. kaushik (2015). antimicrobial activity and identi�cation of potential antimicrobial compounds from aquatic pteridophyte, azolla microphylla kaulf. indian journal of experimental biology, 53(4); 232– 235 blahova, l., o. adamovsky, l. kubala, l. svihalkovd, r. zounkova, and l. blaha (2013). the isolation and characterization of lipopolysaccharides from microcystis aeruginosa, a prominent toxic water bloom forming cyanobacteria. toxicon, 76; 187–196 gunawan, i. (2009). potential of bitter melon fruit (momordica charantia l.) as antibacterium for salmonella typhimurium. faculty of teacher training and education, mahasaraswati university, denpasar ismail, a., z. marjan, and c. foong (2004). total antioxidant activity and phenolic content in selected vegetables. food chemistry, 87(4); 581–586 juliantina, f. (2008). the bene�t of red sirih (piper crocatum) as antibacterial agent to gram positif and gram negative bacteria. journal of indonesian medical and health, 1(1); 12– 20 moshi, m. and z. mbwambo (2005). some pharmacological properties of extracts of terminalia sericea roots. journal of ethnopharmacology, 97(1); 43–47 muniappan, k., p. mahalingam, and m. therasammal (2016). studies on molecular identi�cation of anabaena cyanobionts of azolla species. iosr journal of pharmacy and biological sciences (iosr-jpbs), 11((6); 53–56 renuka, n., a. guldhe, r. prasanna, p. singh, and f. bux (2018). microalgae as multi-functional options in modern agriculture: current trends, prospects and challenges. biotechnology advances, 36(4); 1255–1273 rossana, a., m. valdirene, f. ana, and m. candvania (2006). e�ect of proteins from the red seaweed hypneamusciformis © 2018 the authors. page 186 of 188 gofar et. al. science and technology indonesia, 3 (2018) 183-188 table 2. test of capability di�erences of a. azolae extraction from a. microphylla and a. pinnata leaves on activity of x. oryzae bacterium source of a. azollae extraction solvent inhibitory zone diameter (mm) t-calculated t-table 0.05 on activity of x.oryzae bacterium azolla microphylla ethyl acetate 13 4.23* 2.13 azolla microphylla methanol 10 azolla pinnata ethyl acetate 15 5.12* 2.13 azolla pinnata methanol 11.5 on activity of p. oryzae fungus azolla microphylla ethyl acetate 16.25 5.39* 2.78 azolla microphylla methanol 22.25 azolla pinnata ethyl acetate 15.58 5.76* 2.78 azolla pinnata methanol 21.33 table 3. probability, area and retention time of compound formed from a. azollae extracted from a. pinnata and a. microphylla leaves extraction sources compound formed probability (%) area (%) retention time (minutes) a. pinnata with ethyl acetate solvent phytol 74.09 15.88 19.56 hexadecanoic acid 68.27 16.01 18.74 a.microphylla with ethyl acetate solvent phytol 73.68 11.89 19.55 hexadecanoic acid 77.57 15.29 18.26 a. pinnata with methanol solvent 2-(tert-butyl)-4,6dimethyl phenol 95.81 17.05 22.1 hexadecanoic acid 76.23 12.67 18.25 a. microphylla with methanol solvent 2-(tert-butyl)-4,6dimethyl phenol 69.69 10.62 19.55 hexadecanoic acid 60.22 14.84 18.5 © 2018 the authors. page 187 of 188 gofar et. al. science and technology indonesia, 3 (2018) 183-188 (wulfen) lamouroux on the growth of human pathogen yeasts. brazilian of biology and technology, 49; 915–921 salman, j. and w. m.m (2016). activity of cynophyta algal extracts(anabaena azolla) against some species of fungi in local habitats. mesopotemia environmental journal, 3(1); 1–9 swain, s. s., s. k. paidesetty, and r. n. padhy (2017). antibacterial, antifungal and antimycobacterial compounds from cyanobacteria. biomedicine & pharmacotherapy, 90; 760–776 widiana, r. (2012). konsentrasi hambat minimum (khm) ekstrak daun teh (camellia sinensis l.) pada escherichia coli dan salmonella sp. jurnal pelangi, 4(2) © 2018 the authors. page 188 of 188 introduction experimental section extraction of anabaena azollae preparation of bacteria and fungi preparation of test media test of antibacterial and antifungal activities results and discussion test of antibacterial and antifungal activities the compounds available in a. azolae extract conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 3, july 2021 research paper heterogeneous catalytic conversion of citronellal into isopulegol and menthol: literature review amri yahya1, dwiarso rubiyanto1, is fatimah1* 1chemistry department, universitas islam indonesia, kampus terpadu uii, jl. kaliurang km 14, sleman, yogyakarta, indonesia, 55584 *corresponding author: isfatimah@uii.ac.id abstractthe conversion of citronellal into isopulegol is a key route in the production of a number of important chemicals. in the perspectiveof green conversion, the use of a heterogeneous catalyst is superior due to its ease in separation and reusability, so it facilitatesa highly economical conversion. in this review, we examine the use of some transition metals in cyclization reactions, which aresuitable for citronellal conversion into isopulegol, and consider the potential progress in clay-based catalysts. the structure of claywhich potentially provides the porosity by modification and supporting active metal is proposed to be the low-cost catalyst for theconversion. as other mechanism by porous materials-supported metal, the porosity of clay support contributes to conduct thesurface adsorption mechanism and the broensted acid supply, meanwhile the metal acts as active site for cyclization, and in theone-pot conversion into menthol, as both cyclization and hydrogenation. keywordscitronellal, isopulegol, menthol, catalysis process received: 7 february 2021, accepted: 14 june 2021 https://doi.org/10.26554/sti.2021.6.3.166-180 1. introduction along with the increasing demand for valuable chemicals in drug, food, and therapeutics applications, new strategies are developing for exploring raw materials derived from natural products, including essential oil derivative products (sharma et al., 2019). in the pharmaceutical industry, the search continues for new bioactive compounds derivatives from essential oil products. one of the secondary metabolites that plays a role is citronellal. citronellal has the potential to be used as a raw material for natural medicine and anticancer drugs (de sousa, 2015; lenardão et al., 2007). citronellal is known to be cheap, readily available, and a very versatile starting material for some organic syntheses, including the asymmetric synthesis of chiral compounds used for producing aroma products such as pheromones, perfumes, and essences (da silva et al., 2004; jung et al., 2012; yadav and lande, 2006). some processes for citronellal conversion play important roles for such platforms, including the strategic steps of extraction, characterization, racemic separation, and catalytic conversion. in addition to its direct use in therapeutics, citronellal is used in conversion reactions to obtain its important derivatives (jung et al., 2012). the isomerization of citronellal into isopulegol. the reduction into citronellol, and the direct and indirect conversion into menthol are valuable reactions in industry. for example, considering the world’s large consumption of menthol in avors for food and scents for toiletries, it would seem that menthol will remain in high demand. in the perspective of sustainability and increasing process eciency, the optimization of citronellal extraction and conversion, including catalytic conversion, with intensied procedures is considered a crucial point (knirsch et al., 2010). this review discusses the facts about, potential developments in, and optimization of citronellal extraction and conversion. as the main route in menthol production, catalytic conversion of citronellal into isopulegol and menthol is highlighted. numerous papers have reported using heterogeneous catalysts for the single conversion of citronellal to isopulegol and the one-pot conversion into menthol (adilina et al., 2015). the combined transition metal and solid supports were functionalized within the conversion mechanism. 2. citronella oil: source and extraction method citronellal is a tradename of 3,7-dimethyl-6-octenal (structure is presented in figure 1). citronellal is a monoterpene, predominantly formed by the secondary metabolism of plants, which is usually derived as an essential oil through distillation and extraction. citronellal, along with other terpenes such as citral, geranial, linalool, and citronellol, is typically isolated from more than 30 plants that produce essential oils (lenardão https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.3.166-180&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.3.166-180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 figure 1. conversion of citronellal et al., 2007). table 1 presents some methods for citronella oil extraction. the predicted annual production of citronella oil is around 2300 metric tons, and derived from many sources such as cymbopogon nardus, cymbopogon citronella, and cymbopogon winterianus (hamzah et al., 2013; salea et al., 2018). these plants are easily cultivated with no specic requirements, increasing the ease with which citronella oil can be produced. generally, the citronellal is present together with other components such as citral, neral, and terpenes. two types of citronella oil are known commercially: ceylon citronella oil, obtained from cymbopogon nardus (inferior type), and java type citronella oil obtained from cymbopogon winterianus (superior type). the ceylon chemotype consists of geraniol (18–20%), limonene (9–11%), methyl isoeugenol (7–11%), citronellol (6–8%), and citronellal (5–15%). the java chemotype consists of citronellal (32–45%), geraniol (11–13%), geranyl acetate (3–8%), and limonene (1–4%) (salea et al., 2018). dierent methods of distillation have been reported, such as extractive distillation, hydrodistillation (hd), steam distillation, and soxhlet extraction, along with their process intensication strategies. hydrodistillation, considered to be the most traditional method, has manyintensication procedures, forexample, ohmic-assisted hydrodistillation (oahd), which is the combination of ohmic heating and hydrodistillation (gavahian et al., 2018). oahd has been reported as an eective method to enhance extraction performance by faster heating compared to other methods. heat inside the materials is generated and the temperature is raised faster in oahd than in conventional heating methods (gavahian et al., 2018). this experiment reported by gavahian et al., 2018 revealed an increase in yield of valuable compounds from cymbopogon leaves, including a 3.6% higher yield of citronella oil compared to conventional distillation. another similar enhancement of hydrodistillation is microwave-assisted hydrodistillation (mahd). the eective molecular heating within the essential oil extraction by mahd reduced the extraction time by 67% when compared to conventional distillation (milone et al., 2000). the use of mahd for figure 2. synthesis of menthol from citronellal (plößer et al., 2016) citronellal extraction from cymbopogon citratus produced higher yields and faster extraction times compared to conventional distillation: mahd gave a yield of 0.35% v/w for a 90-minute extraction time, while conventional distillation gave a yield of 0.15% v/wfora360-minute extraction time (tran et al., 2019). the intensication process of extraction can be performed with supercritical carbon dioxide, microwave irradiation, and sono-hydrodistillation (hamzah et al., 2013; solanki et al., 2018). various optimum conditions involve parameters such as temperature, pressureandrawmaterial loading. thesignicant increase in yield is due to the increase in density and solvency power, and it depends on operating parameters and the solvent. for example, the supercritical carbon dioxide extraction of citronella grass by compressed propane exhibited an increased kinetic constant and equilibrium yield (guedes et al., 2018). compressed propane showed a higher equilibrium yield and kinetic constant than supercritical co2 under similar conditions (40◦c and 6-9 mpa). however, supercritical co2 is a non-toxic and lipophilic alternative solvent with applicable critical temperature and pressure in industrial practice. the addition of ethanol to the solvents increased both equilibrium and kinetic properties even more, because the co-solvent interacts with the polar fraction, playing a complementary role along with the non-polar propane or co2. it is important to mention that the best results were obtained for the runs using a compressed propane solvent at 60◦c and 2 mpa and supercritical co2 (solvent) with ethanol (co-solvent), with an ethanol-to-raw-material mass ratio of 1:1. 3. citronellal conversion into isopulegol and menthol as shown in figure 2, citronellal can be converted into isopulegol, neoiso-isopulegol, citronellol, iso-isopulegol, neoisopulegol, and menthol. the conversion of citronellal into isopulegol is a pathway in the production of menthol, which is widely utilized in the pharmaceutical, soap, and toothpaste industries raut and karuppayil (2014). isopulegol has been reported as a good antioxidant and anti-inammatory (ramos et al., 2020), antihyperlipidemic (kalaivani and sankaranarayanan, 2019), analgesic (kalaivani and sankaranarayanan, 2019), and antitumor agent © 2021 the authors. page 167 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 table 1. some methods for citronella oil extraction source extraction method remark reference cymbopogon ohmic-heated hydrothe maximum amount of (hamzah et al., 2013) nardus distillation, hydro-distillation, extracted oil yield by ohmic and steam distillation heated hydro-distillation was 7.64 ml/kwh, by hydro-distillation was 3.87 ml/kwh, and by steam distillation methods was 1.69 ml/kwh, respectivel cymbopogon supercritical co2 the highest essential oil yield (wu et al., 2019) citronella l extraction (sfe) was predicted at extraction time 120 min, extraction pressure 25 mpa, extraction temperature 35◦c, and co2 ow 18 l/h for the sfe processing cymbopogon manual extraction and average percent yield in (wany et al., 2013) winterianus hydro-distillation the manual extraction and jowitt hydro-distillation procedure was 0.8 and 1% respectively, which was better as compared to steam distilled oil (0.7%) cymbopogon sono the optimum yield of oil was (solanki et al., 2018) winterianus hydrodistillation obtained as 4.118% (w/w) at 21 jowitt min extraction time, and 5 g solid loading taiwanese hydrodistrillation (hd) hd and oahd gave similar yield, (gavahian et al., 2018) citronella and ohmic-assisted but oahd saved 46% and 79% grass hydrodistillation (oahd) of the process time and energy, respectively. cymbopogon microwave-assisted mahd produced higher yield and (moradi et al., 2018) citratus hydrodistillation (mahd) faster time (0.35% v/w, 90 min) compared to conventional distillation (0.15% v/w, 360 min) citronella supercritical co2 the supercritical carbon dioxide (guedes et al., 2018) grass extraction extraction of citronella grass by compressed propane exhibited the increased kinetic constant and equilibrium yield cymbopogon supercritical co2 high selectivity was obtained at (silva et al., 2011)nardus extraction 353.15 k and 18.0 mpa, with a more pure essential oil cymbopogon supercritical co2 the highest citronella oil yield (3.206%) (salea et al., 2018)winterianus extraction was achieved at a factor combination of 15 mpa, 50 â°c and 180 min © 2021 the authors. page 168 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 table 2. mechanism of intramolecular cyclization reactions in various catalysts catalyst compound mechanism target compound conversion (%) reference pbu3 n-allylic intramolecular 𝛼-amino nitril (zheng et al., 2016)cyclization cu(ii) (1,4 phenylene)intramolecular benzodiimidazole99 (mesias-salazar et al., 2020) bisguanidines cyclization diylidenes cu(i) (1,4 phenylene)intramolecular 1-aryl-1h-benzotriazole 97 (liu et al., 2010) bisguanidines cyclization au(iii) 𝛼-pyrroles intramolecular pyrrolopyridinones and 68 (li and lin, 2015) cyclization pyrroloazepinones fe(ii) alkynes and intramolecular 1,3-oxathiane derivative 98 (sonehara et al., 2017) thiosalicylic acid cyclization rh(iii) isoquinolone intramolecular indolizidine 65-77 (xu et al., 2012) anulation pt(ii) o-isopropyl-substi intramolecular indenes (wang et al., 2014) tuted aryl alkynes cyclization cs(iii) 2-bromoindoles intramolecular 2-(gem-bromovinyl)-n(li et al., 2013) cyclization methylsulfonyl-anilines rh(iii) arylnitrones intramolecular indolines (liu et al., 2016) cyclization ti(iv) isatins and 5cyclization spiro[3,3’-oxindoleoxazoline] >99 (badillo et al., 2011) methoxy oxazole zr(ii) citronellal intramolecular isopulegol (tobisch, 2006) cyclization zn(ii) citronellal intramolecular isopulegol 94 (imachi et al., 2007) cyclization ru(iii) citronellal cyclization and menthol 80 (azkaar et al., 2019) hydrogenation pt(ii) citronelal cyclization and menthol 85 (azkaar et al., 2019) hydrogenation nis citronelal cyclization and menthol 100 (cortés et al., 2011) hydrogenation (jaafari et al., 2012). isopulegol is also the intermediate for the synthesis of the anti-inuenza compound octahydro-2hchromenes ilyina et al., 2021 and bioactive 2h-chromene alcohols as an antiviral agent (laluc et al., 2020). exclusively, isopulegol, especially (–)-isopulegol, is the starting compound in the production of menthol, which is a compound in high demand throughout the world (coman et al., 2009; plößer et al., 2014). menthol is of prime importance in avoring and pharmaceutical applications, as it elicits cooling and “fresh” sensations. menthol is a chiral compound that can occur as eight possible stereoisomers: (±)-menthol, (±)-neomenthol, (±)-isomenthol and (±)-neoisomenthol. of these, (–)-menthol is the product of interest. at the industrial level, menthol production is performed by the takasago process, which involves citronellal isomerization on an aqueous znbr2 catalyst (brunner, 2020; nicolaou et al., 2000). the conversion of citronellal into isopulegol consists of acid-catalyzed cyclization, and the conversion of isopulegol into menthol includes hydrogenation (figure 2). instead of enzymatic conversion (bastian et al., 2017), isomerization by a chemical catalyzed process, which takes on the role of acid catalysis, is chosen due to the eectiveness of the isomerization mechanism (shah et al., 2018). in terms of energy eciency, selectivity, and repeatability in the industrial scale, these conversions require eective catalytic processes and catalysts. in previous research and industry alike, citronellal isomerization and cyclization took place with a variety of homogeneous catalysts, but the catalysts often created disposal problems and were dicult to separate and recover (guidotti et al., 2000; vetere et al., 2002). using the green chemistry perspective, the replacement of homogeneous catalysts with heterogeneous catalysts, in which the phase of the catalyst and reactants dier in form, is a viable alternative. the mechanism of heterogeneous catalysis consists of the surface reaction, which reduces the activation energy of the reaction, as schematically represented in figure 3. the capability of heterogeneous catalysis to conduct adsorption of the reactants is the main point for the mechanism, and as it happens, the surface interaction among the adsorbed reactants is the crucial step for nally producing and releasing the products. the transition metals and their combination with solid supports are widely used, adapted with the characteristics of the reaction. as the citronellal conversion into isopulegol involves the acid catalysis mechanism, the transition metals such © 2021 the authors. page 169 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 figure 3. general mechanism of surface reaction in heterogeneous catalysis as ruthenium (ru), pt, zr, and ir were reported to be eective due to the availability of the lewis acid sites. the availability of the d-orbital of the transition metal acts as a lewis acid, which is capable of forming a bond with a 𝜋-electron of the double bonds of the reactant (citronellal). in separating this way, the conversion of isopulegol into menthol is through a hydrogenation mechanism, which in particular involves the capability of the catalyst to adsorb hydrogen (h2). some metals such as ni, pt and au were reported to have excellent activity for this mechanism (azkaar et al., 2019; plößer et al., 2014). the combination of lewis acidity from transition metals and the solid support consisting of broensted acidity and a high surface area gave an excellent improvement in yield and eectivity of the reaction. the solid supports provide not only stability in sites for reactant adsorption, but also, especially for the porous materials, an advantage in the catalyst stability and reusability. in addition, heterogeneous catalysts allow for regeneration and reusability, and some specic heterogeneous catalysts can provide direction for increasing the selectivity of the structure of certain products and the properties of the catalyst (coman et al., 2009). to our knowledge, the review on heterogeneous catalytic conversion of citronellal into isopulegol and menthol is not yet presented. considering the importance of isopulegol as intermediate for many compounds, and menthol in various applications, the aim of this review is to discuss potential heterogeneous catalysts in green conversion of citronellal to isopulegol and menthol. 4. citronellal conversion into isopulegol citronellal conversion into isopulegol possesses a strategic pathway, one route of which leads to the production of menthol, consisting of two processes: citronellal cyclization and hydrogenation. in addition to preventing unwanted hydrogenation of citronellal, dimerization and defunctionalization (forming p-menthenes and p-menthanes), the challenge of using heterogeneous catalysts lies in the formation of diastereoisomers, namely isopulegol, iso-isopulegol, neo-isopulegol, and neoisoisopulegol, as shown in figure 4 (plößer et al., 2016). although in industrial applications the mechanism of the citronellal cyclization reaction is still under debate, one proposed mechanism of the cyclization reaction occurs through protonation of the citronellal carbonyl group, which takes place after a stable carbocation is formed by intramolecular rearfigure 4. citronellal cyclization gives four diastereoisomers (vandichel et al., 2013) rangement, and ends with the deprotonation that produces isopulegol (makiarvela, 2004). the takasago process, in which (–)-menthol is produced by the hydrogenation of (–)-isopulegol obtained from (+)-citronell al through acid catalyzed cyclization, is an important reaction in pharmaceutical industries (cortés et al., 2011). the mechanism includes the ene-cyclization of (+)citronellal to (–)-isopulegol over aqueous znbr2 as a homogeneous catalyst, which causes a large amount of waste due to its nonregenerability. in order to make the process commercially attractive, synthesis of isopulegol with high stereoselectivity for the isomer (–)-isopulegol is important. many studies highlighted that the selectivity is closely related to lewis acidity (shah et al., 2018; milone et al., 2000; shieh et al., 2003). with this background, most methods of the synthesis of heterogeneous catalysts were focused on activity, selectivity and stability, mainly by anchoring or immobilizing acid sites on stable inorganic materials. such porous mediaas silica-alumina and silica-based materials were reported to be good supports (shieh et al., 2003). combined experimental and theoretical studies reveal that the catalytic mechanisms and characteristics play a role in evaluating the catalyst performance and the selectivity of lewis acids toward the desired stereoisomers (sekerová et al., 2019). some of the lewis acid catalysts used are zn, zr, ti and a ni-based catalyst in supported form (chuah et al., 2001; fatimah et al., 2008; guidotti et al., 2000; jimeno et al., 2013). the result is that a lewis acid catalyst becomes the main factor that contributes to the selectivity and catalytic activity of the cyclization reaction (vandichel et al., 2013). a lewis acid can act as an electron pair acceptor, as znbr2, zncl2, and zni2 can act as catalysts for citronellal cyclization (nisyak et al., 2017). the mechanism of citronellal cyclization is shown in figure 4. one type of lewis acid catalyst is the zirconium-based catalyst. the results of research by chuah et al., 2001 showed that zirconium hydroxide and zirconium phosphate catalysts also have activity and selectivity in the cyclization reaction of citronellal to isopulegol. the presence of lewis and bronsted acid catalyst sites is very important in the citronellal cyclization reaction, as depicted in the reaction mechanism proposed in figure 5 (álvarez-rodríguez et al., 2012; fatimah et al., 2014; ravasio et al., 2000; sudiyarmanto et al., 2017). the mechanism begins with the formation of a citronellal coordination bond to a lewis acid through free electrons of carbonyl o atoms and 𝜋 electrons of citronellal alkenes to zr © 2021 the authors. page 170 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 figure 5. mechanism of citronellal cyclization (tursiloadi et al., 2015) atoms, followed by protonation of the bronsted acid (–zr-oh) sites against citronellal carbonyl o atoms (chuah et al., 2001). in line with the previous results, the conversion of citronellal to isopulegol was successfully conducted through a cyclization mechanism with a znbr2/𝛽-zeolite catalyst (balu et al., 2010). the result is that the znbr2/𝛽-zeolite catalyst provides better activity than the 𝛽-zeolite catalyst alone, where forznbr2/𝛽-zeolite the conversion value of citronellal to isopulegol is 100%, with a selectivity to isopulegol compounds of 75.28% at 120◦c and a reaction time of 60 minutes. by a similarmechanism,znbr2/sio2 catalyzedcitronellaloil conversion gave a selectivity to isopulegol of 94.35%, and a conversion of 96.44% (nuryanti et al., 2019). the mechanism of the cyclization reaction involves the formation of a ring compound from the chain by the formation of new bonds. the cyclization reaction is an intramolecular reaction where the reaction occurs in the molecule itself. the factors that inuence the relationship between structure and reactivity intramolecularly include: induction, resonance, steric eects and hydrogen bonding. the intramolecular cyclization mechanisms in various metal catalysts are presented in table 2. it is seen that the presented reaction conversions are quite high (68–100%), which further conrms that the conversion is related to the eective interaction between the metal catalyst and the 𝜋-bonds of the organic molecule (li and lin, 2015). based on the study of density functional theory (dft), the transition state is coming from the linking between the active sites of the metal catalyst and the 𝜋-bonds. the bonding results in the potential energy surface near the stationary point and involves the activation of c=c bonds (double or triple bonds). the possible charge distribution among the resonance structures of molecules will lead to electron-rich properties of the internal alkyne carbon, which is thus more nucleophilic than the carbonyl carbon. the increasing energy facilitates the 1,2-migration of the internal alkyne carbon from the pyrrole’s 𝛼to 𝛽-carbon. the shifting energy also accelerates the interaction with hydrogen in the subsequent hydrogenation step (li and lin, 2015). table 2 shows some transition metals in the cyclization mechanism, especially in the regiospecic organic synthesis. the presence of the active site provides transformation and indicates a highly convergent route to a wide variety of carbocyclic and heterocyclic structures. the pbu3 catalyst acts as a lewis base to strengthen the nucleophilicity of the active reaction site (zheng et al., 2016). in addition, the cyclization reaction can be carried out with lewis and bronsted acid catalysts. lewis acidity plays a role in providing coordination bonds for unsaturated metal ions, whereas bronsted acidity plays an important role not only as an activating agent, but also in controlling the diastereoselectivity of reactions through hydrogen bonding interactions (vetere et al., 2002). from the perspective of time eciency and minimizing waste, the one-pot conversion of citronellal into menthol is a better approach (cortés et al., 2011; makiarvela et al., 2005). bifunctional catalysts and the superacid solid catalysts act properly for both mechanisms. one-pot reactions catalyzed by pt−, ru−, and ni−based catalysts were reported (cortés et al., 2011). similar to other organic reaction mechanisms with transition metal catalysts, the supporting materials inuence either the dispersion and stabilityof the active metal or the mass transfer of the reactant feed for conducting surface reactions. table 3 lists the activity of some porous material-supported metal catalysts in the citronellal conversion. the interaction between the active metal and the support plays a role in controlling the surface reactivity, and furthermore, the conversion and selectivity. for example, when producing menthol on an mcm-41 support, the reactivity and selectivity of the active metals rank in the following order: ni > pd > ru > ir (makiarvela et al., 2005). the ratio of bronsted to lewis surface acidity governs the possible side reactions. this is also identied by the use of ni-supported material on clay minerals (fatimah et al., 2015; fatimah et al., 2016). from table 3, it can be seen that although in general the higher the specic surface area of the catalyst, the higher the conversion, the catalytic conversion and selectivity in cyclization and hydrogenation is not only inuenced by the specic surface area of the supports, but also by their interaction with the supported metal. acidity of the supports provides the surface acidityforsucientlypromoting the cyclization step, while the presence of supported metal enhances the catalyst-reactant adsorption surface interaction upon formation of isopulegol, as well as the hydrogen transfer in hydrogenation (imachi et al., 2007; balu et al., 2010). the dominant silica content in the solid supports tends to promote bronsted acid, while the presence of al gives a combination of bronsted and lewis acidity. in addition, for the hydrogenation step, the study from nie et al., 2006 showed an increasing ni loading from the ni/bea © 2021 the authors. page 171 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 table 3. comparison on activities of some metal-supported porous materials in citronellal conversion catalyst metal surface surface acidity conversion selectivity selectivity referencecontent area (%) to isopulegol to menthol (%) (m2/g) (%) (%) znbr2/c8-hms 2.6 1200 94 86 (imachi et al., 2007) ni/mcm-41 15 659 96 8 74 (nie et al., 2006) ni/natural zeolite 5 29 50 50 0 (adilina et al., 2015) ru/h-mcm-41 10 522 96.4 2.2 46.6 (vajglová et al., 2020) pd/ga-sba-15 1.92 799 65 mmol pyridine/g >90 15 75 (balu et al., 2010) pt/al-mcm-41 2.02 905 199 mmol pyridine/g 95 15 60 (balu et al., 2010) cu/al-mcm-41 1.85 752 210 mmol pyridine/g 90 8 87 (balu et al., 2010) zr/pillared montmorillonite 5 97.5 1.05 mmol butylamine/g 89.8 98.5 (fatimah et al., 2016) ru(bpy)/saponite 1.89 229.35 98.12 95.02 2.58 (fatimah et al., 2015) catalysts that leads to faster hydrogenation and selectivity to produce menthol in a one-pot conversion. particularly, the hydrogenationratewas insignicantly inuencedbythe increasing particle size, for example, in the ru-deposited material on mcm-41 (vajglová et al., 2020), and pt–ga-mcm-41 (balu et al., 2010). the nanoparticles formed from active metals demonstrated a highly stable catalytic activity, as represented by better reusability (balu et al., 2010; fatimah et al., 2019). heterogeneous catalysts suitable for the cyclization reaction of citronellal-enes must have strong lewis acids and weak bronsted acids (chuah et al., 2001). the fast reaction rate of ene reactions in (+)-citronellal cyclization with a sulfate zirconium catalyst aects stereoselectivity. the result is a maximum stereoselectivity of 61%. however, high stereoselectivity (72%) was obtained from a zirconium hydrate catalyst. a zro2 acid catalyst, which has a low surface area, is also active in cyclization. in addition, a high ene reaction rate can also be obtained when using a sio2-al2o3 mixed catalyst with a maximum stereoselectivity of 72%. one of the factors determining the activity of the zro2 and al2o3 catalysts is the dierence in their surface acidity type. zro2 exhibits both bronsted and lewis acid sites, while the acidity of al2o3 comes from the lewis acid only (makiarvela, 2004). figure 6. the reaction mechanism of citronellal cyclization to isopulegol with zirconium hydroxide catalyst (chuah et al., 2001) other factors of the reaction system, such as the ow and batch systems, showed dierent results. the use of the extractivesynthesismethodhasamajor inuenceonphysicochemical properties, especially on the level of bronsted acidity, metal dispersion, and metal distribution in the material. in a batch reactor, ru and pt catalysts each support the acidity independently. this catalyst owsystem does not depend on the acidity of the catalyst or the size of the metal particles, but it does depends on the reaction kinetics, especially the mass transfer. this is evidenced by the stereoselectivity of menthol of 73% (azkaar et al., 2019). 5. clay-based heterogeneous catalysts clay minerals contain silica-alumina frameworks characterized as a layered structure with exchangeable cations that potentially can be replaced with metal or metal oxide. the modication of clay can be conducted based on the exchange of alkali or earth alkali (na+, k+, mg2+, ca2+) cations with other metal cations, giving increasing porosity caused by an expansion of the interlayer distance (banković et al., 2012; barakan and aghazadeh, 2019). cations located in the interlayer space can be exchanged with organic and organometallic cations in solution or in solid conditions (belver et al., 2012; wang et al., 2016). natively, clay minerals containing bronsted acid and lewis acid sites refer to the interlayer charges and the silica content within the structures. as the cation exchange is conducted with polyoxometal cations of transition metals, the formation of lewis acid sites can be achieved instead of the enhancement of chemical interactions, such as hydrogen bonds, ion-dipole interactions, coordination bonds, and transfer forces or van der waals forces. previous studies have reported that tetraalkylammonium compounds can be easily introduced into the interlayer space, causing changes in pore structure and shifting of the interlayer distance (mao et al., 2009; nagendrappa, 2011). however, this thermal material is not stable at temperatures above 250°c. incorporation of metal oxides as pillars increases bronsted and lewis acidity. in addition, this material can be used in redox or cycloaddition reactions as well as catalytic activity due to its high specic surface area (cecilia et al., 2018). according to baloyi et al., 2018, the development of catalysts, with a focus on low cost, stability, reusability and an environmentally friendly aspect, and catalysts such as pillared clays, will lead to the discovery of eective solids as heterogeneous catalysts. in silica-aluminamaterials, clay-based catalysts exhibit ahighsurfacearea, andtheycanbemodiedandreused (chmielarz et al., 2018; kooli et al., 2016). in previous studies, gonzález et al., 2017 reported that montmorillonite had been pillared by al137+ polycations, using concentrated solutions and clay mineral dispersions. the reaction is assisted by microwave radiation, producing a new © 2021 the authors. page 172 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 intercalation solid, and leading to an al pillared solid after calcination at 500◦c. the solids obtained show structural characteristics comparable to those of al-pilc prepared from the classical method (manos et al., 2001; pinto et al., 2012). several modication schemes can be applied to identify a more active catalyst for the homogeneous distribution of metal or metal oxide catalysts in the clay structure. as an eort to preserve the specic surface area along with surface acidity, modiedclaywithaporousstructurewasalsoattempted, oneof these being in the form of a porous clay heterostructure (pch) (kalmakhanova et al., 2019; liu et al., 2007). modication showed that the formation of metal oxides in the interlayer space of the smectite clay structure provides stability, and more importantly, maintains surface acidity in certain acid catalytic mechanisms (cecilia et al., 2018; panda, 2018; radwan et al., 2009). the results of the research by chmielarz et al., 2018 reported that the bet surface area (sbet) was determined for calcined ti-pilc and ti-pch. ti-pilc calcination at 550°c produced samples with the highest surface area of 212 m2/g. at higher temperatures, partial collapse of the ti-pilc pillar structure is possible. the ti-pch calcination at 600°c produced a material with a surface area of 573 m2/g, which is much higher than ti-pilc. in the study of kooli et al., 2017, smectite polarized with various numbers of al species was reported and characterized, and the further use of this precursor was successful in the synthesis of al-pch materials. as a result, a greater specic surface area value was achieved and varied from 740 to 850 m2/g with the acid site. the al content in the pillared clay and the pch derivatives inuence the catalytic data due to the dierent strengths of the acid sites and textures. high surface acidity and surface area are the main factors aecting the increase in catalytic activity. in addition, the advantagesofusingpch,especially inmaintainingsurfaceacidity in many catalytic mechanisms, are mainly attributed to pch (zhouetal.,2013). thecombinationofmetaloxidesandpch is also expected to provide mutually benecial relationships for several desirable properties in the reaction, including catalyst activity and selectivity, referring to the presence of metals as the specicity of the active site (cecilia et al., 2018; chmielarz et al., 2018; kooli et al., 2017). surfactants are another determining factor in pch synthesis. the preparation of the h+-titanosilicate/dodecylamine (dda)/tetraethylortho-silicate (teos) intercalation compo und is rapidly hydrolyzed in water to form h+-titanosilicate pillared siloxane and calcined for 5 hours at 500◦c to produce a mesoporous h+-titanosilicate. the results obtained show a basal distance of 4.16–4.32 nm, a uniform pore size of 2.8–3.4 nm, and a large surface area of 535–618 m2/g. these results suggest that the dda molecule plays a decisive role in pore formation, as it acts as a base catalyst and as a micelle-like template during the hydrolysis of teos and contributes to the formation of solid silica pillars (park et al., 2009). therefore, the schematic of pch formation is shown in figure 7. figure 7. schematic representation of pch formation (rubiyanto et al., 2019) figure 8. schematic representation of citronellal conversion by clay-supported metal the pillared clay can also act as a solid support for other metals or metal oxides, for example, tio2 dispersed in silicapillaredmontmorillonite (tio2/sio2-montmorillonite). previousworkreportedthat theuseofatio2/sio2-montmorillonite catalyst played a signicant role in increasing the total reaction conversion from 87.80% in the use of sio2-montmorillonite and from 85.38% using natural montmorillonite to 95.53% (fatimah et al., 2008). the increase in total conversion and selectivity to isopulegol was related to the lewis acidity of tio2/sio2-montmorillonite and the increase in the specic surface area of the material. however, it is possible that the specic surface acidity plays a greater role than the physicochemical character of the materials in this range. this means that the tio2 dispersion on the sio2-montmorillonite catalyst does not have a signicant role in increasing the reaction rate. changes in physicochemical properties of catalysts by the presence of titanium dispersion play a role in directing the mechanism so that it plays a signicant role in the selectivity and catalytic activity. figure 8 represents the mechanism of citronellal conversion using clay-supported metal/metal oxide. theverysimple inorganicmaterial,montmorillonite,which is a natural acid clay, can eectively promote the synthesis of nitrogen-containing octahydroacridine, with 92% yield in one hour and at room temperature, ranging from aniline and cit© 2021 the authors. page 173 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 ronellal, as well as the main components of several essential oils. the use of a solid acid catalyst gives a high selectivity to isopulegol compounds. therefore, the use of solid acid catalysts can minimize waste and shows high potential for sustainability (zaccheria et al., 2018). the synthesis of zr-montmorillonite in acetonitrile is used inthecitronellalcyclizationreaction. thepresenceandstrength of lewis acid catalyst zr-montmorillonite plays a role in producing isopulegol 98% with stereoselectivity to (–)-isopulegol 90%. as some lewis acids are used that are stronger than ti4+/zr4+, such as al2o3, sio2-tio2 and sio2-zro2, the stereoselectivity with respect to the (–)-isopulegol are 70, 62, and 62%, respectively. the type of lewis acid carried on mesoporous materials, znbr2/sio2, can produce (–)-isopulegol with a maximum stereoselectivity of 86% (makiarvela, 2004). guidotti et al., 2000 suggested that the conversion of citronellal to isopulegol epoxide using a mesoporous titanium silicate catalyst (ti-mcm-41) in one step at the same time resulted in 68% yield. the cyclization process of citronellal to isopulegol takes place in a toluene solvent for 6 hours, and then tertbutylhydroxyperoxide (tbhp) and acetonitrile are added to convert isopulegol to isopulegol epoxide for 18 hours at 76% and selectivity 90%. a catalyst consisting of nickel dispersed in zeolite (ni/zab) was also reported to be eective for the conversion of citronellal oil to isopulegol from lemon grass oil, which reached a total conversion of 100% and a selectivity of 57% (tursiloadi et al., 2015). the signicant role of specic surface area was summarized from the signicant increasing citronellal conversion and selectivity toward isopulegol over zn-dispersed-in-clay, via the formation of a porous clay heterostructure (zn/pch), accordingto(rubiyantoetal.,2019). thephysicochemicalproperties increase in line with the increase in catalytic activity and selectivity in the conversion of citronellal to isopulegol, compared to zn/pillared clay (zn/pch). zn/pch showed a 98.9% conversion rate for the 3-hour reaction and 100% selectivity for isopulegol production, and showed good reusability. surface acidity enhancement was also reported for a combination of bimetals: nickel and zirconium in the form of nickel immobilized zirconia pillared saponite (ni-zr/sap). zr-pillared saponite (zr/sap) was prepared by microwaveassisted pillarization, and it was employed as the solid support of nickel by the impregnation method. the physicochemical characterization identication showed that zirconia was successfully distributed as pillars, and nickel was dispersed in the pillared material. both modications increased the specic surface area, pore volume and surface acidity as a result of the formation of pillars and homogeneous particle distribution. compared to saponite and zr/sap, the ni-zr/sap composite demonstrated a signicant improvement in citronellal conversion and selectivity towards isopulegol. the presence of nickel plays a role in the one-pot conversion of isopulegol into menthol over a catalytic hydrogen transfer reaction. as nickel has specialization for hydrogenation mechanisms, ni-zr/sap produced menthol in a signicant selectivity (13%) (fatimah et al., 2016; fatimah et al., 2015). it was reported that the selectivity in producing menthol was inuenced by the reaction method, forwhich themicrowave-assistedhydrogenationshowedhigher conversion and selectivity compared to the conventional reux method, but for both methods, isomenthone as another hydrogenation product was identied. the increasing quantity and distribution of surface acidity can be achieved by dispersion in a clay support via pillarization. zirconium-pillared montmorillonite (zr/mmt) demonstrated the increased surface acidity that was in line with the increased citronellal conversion into isopulegol, according to fatimah et al., 2014. moreover, the surface acidity enhancement was achieved by sulfation into the form of sulfated-zr/mmt (s-zr/mmt). the contribution of pillarization through increasing specic surface area by the higher basal spacing d001 of the structure, together with the formation of zro2 pillars, were the factors identied for the catalytic activity. in addition, by the anchored sulphate functional groups on the surfaces, the super-acidity of the surface was created, reected as the highest activity of 98.52% citronellal conversion obtained by s-zr/mmt. in a dierent form, the dispersed active metal catalyst of tris(bipyridine) ruthenium (ii) into a saponite clay support (ru(bpy)3/sap) for the bifunctional conversion was also reported. the (ru(bpy)3/sap) exhibited activity in citronellal and citral conversions in catalytic hydrogen transfer under the microwave irradiation method. the hydrophobicity of the complex provides the possibility of acidity transfer as demonstrated by the activity in a non-solvent reaction system. the anchored metal complex in the support is remarkably maintained for 5 uses in its recycling activity (fatimah et al., 2019). considering the role of surface acidity on the catalyst, hydrophobicity, and maintenance of catalyst performance in terms of reusability, the chosen heteropoly acid (hpa) catalysts in clay supports is hypothesized to give more eective catalytic mechanisms. the majority of catalytic applications of hpa are related to the stable and stronger acidity coming from the available keggin hpas heteropoly anions of the formula [xm12o40]n, where x is the heteroatom (such as p 5+ and si4+) and m is the addendum atom (such as mo6+ and w6+). tungsten (w) is a transition metal and has various catalytic applications in the form of tungsten sulde, tungstic acid, polyoxotungstates (hpw) and polyoxometallics (pom). the advantages of tungsten, especially in its heterogeneous form, are itshighbronstedacidity, redoxability, thermalstability, and hydrophobicity (nagendrappa, 2011; telalović et al., 2010; zhou et al., 2013). hpws possess stronger acidity than conventional solid acid catalysts such as zeolites, acidic metal oxides, and mineral acids. theacidityofconcentratedaqueousandnon-aqueoussolutions of hpwis higher than that of h2so4 and hclo4 by about 1.5 or0.3 units of the hammett acidity function. the acid strength ofkegginhpwsdecreases in thefollowingorder: h3pw12o40 > h4siw12o40 > h3pmo12o40 > h4simo12o40 (alsalme et al., 2010). the superacidity characteristics of hpws al© 2021 the authors. page 174 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 low them to catalyze esterication activity of oleic acid with methanolat roomtemperatureandtodisplayahigheresterication activity compared to amberlyst 35w resin (alsalme et al., 2010; nogueira et al., 2020). similarly, the hpw exhibited a high activity of 1-propanol and 1,1-diacetates from a variety of aldehydes at room temperature (heravi et al., 2006). the conclusions from many studies on hpw catalysis have demonstrated the usefulness of hpw, being more eective than ordinary protonic acids. emphasis is placed on the optimization of hpw as a reusable catalyst with high performance to achieve the economic and technical advantages in applications, and one of various alternative methods is the immobilization of hpa onto porous material. the studyon immobilization of 12-tungstophosphoric acid (hpw) on the catalytic activity of h3pw12o40/mesoporous acid activated bentonite (aab) was carried out. the results showed that the 2-propanol transformation increased substantially with the conversion, and the reaction selectivity also increased with increasing hpw concentration. in addition, the proposed catalyst increases the oxidation of 2-propanol to acetone and suppresses the dehydration of propanol to acidcatalyzed propylene. the catalytic activity increases the formation of acetone and decreases the activityof propene formation, which indicates that a catalyst with a high hpw concentration can function as an ecient catalyst for oxidation reactions (rožić et al., 2011). immobilization of hpw and pot into supports such as polymers, silica, alumina, zeolites, and carbon materials not only increases the stability of the pot supported through covalent bonding, but also increases the spread of the pot active site into the support. at present, although tungsten based heterogeneous catalysts are used in industry with high eciency for some reactions, regeneration of pom-based catalysts is generally dicult. therefore, to encourage the use of w-based heteropoly acid catalysts, it is very important to develop catalytic systems that can be regenerated eciently through catalyst heterogenization (enferadi-kerenkan et al., 2018). silica supported h3pw12o40 (pw), which has high hydrophobicity, and which is the strongest heteropoly acid in the keggin series, is an ecient, environmentally friendly heterogeneous catalyst for the liquid-phase isomerization of a-pinene and longifolene into their more valuable isomers–camphene and isolongifolene (da silva rocha et al., 2009). the environment friendly benets of the catalyst can be derived from its ease of separation from the reaction system without neutralization, and it may be easily reused (robles-dutenhefner et al., 2001). according to cortés et al., 2011, an h3pw12o40/sio2 catalyst was used to convert (+)-citronellal to (–)-isopulegol and (+)-neo-isopulegol as the main products with almost 100% conversion, with a total selectivity between 95 and 100%, and 80% are selective against (–)-isopulegol. the catalyst can be used repeatedly without decreasing activity. while the pdh3pw12o40/sio2 catalyst is an ecient heterogeneous bifunctional catalyst forconversion in one process from (+)-citronellal to menthol with aconversion result of up to 92%, and 85% stereoselectivity for the desired product (menthol) (da silva rocha et al., 2007). meso/macroporous h3pw12o40/ sio2 nanocomposites with high specic surface area were prepared using cationic surfactants and monodispersed polystyrene (ps) as dual templates. the results of x-ray photoemission spectroscopic (xps) measurements showed a high dispersity of keggin-type heteropoly acids (hpa) on the silica matrix. there is an optimum value for the use of cationic surfactants and the right calcination temperature of the h3pw12o40/sio2 meso/macroporous catalyst which leads to a very high specic surface area of 1,457.7 m2/g at a calcination temperature of 450°c (yue et al., 2020). in addition, several materials containing tungsten oxide (wo3) were prepared and deposited on sio2 by the sol-gel method and the wet impregnation method. the tungsten oxide weight varies (1, 10, 25 and 40 wt%), namely w10, w25, and w40. the wo3-sio2 catalytic activity of these materials was tested in the intramolecular citronellal prins cyclization reaction. the reaction conditions (temperature 70–90°c, amount of catalyst 1–10% catalyst density) had an eect on citronellal conversion and selectivity in producing isopulegol. the best results (90% isopulegol, 97% selectivity of isopulegol formation, 24 hours) were obtained using the imp w25 catalyst (10 wt%, 50°c). it is possible to reuse the w25 catalyst twice without losing signicant activity. the available materials indicate a suitable catalyst for citronellal cyclization (vrbková et al., 2020). in a study by braga et al., 2012, it was reported that a catalyst based on 12-tungstophosphoric acid supported on mesoporous mcm-41 (2–40 wt%) was prepared and tested in citronellal cyclization. the characterization of the ingredients conrmed the keggin anion treatment. these materials give rise to acidity that is related to the presence of bronsted and hydrogen bond sites. the increase in hpw load is directly proportional to the number of bronsted sites in the material. all the catalysts that were actively prepared in the citronellal cyclization formed the main stereoisomer (–)-isopulegol, but kinetic studies showed that 20% hpw/mcm-41 had the best performance with a conversion of about 96% and a selectivity of 65% foran hourreaction. this catalyst was reused four times with a low deactivation rate, keeping the selectivity almost the same. thus, the successful application of hpw supported on mcm-41 for this acid-catalyzed cyclization is demonstrated, and detailed information on the stability of the catalyst as well as the kinetics of the reaction is provided. 6. future perspective thecombinationofsurfaceacidityandporosityofsupportwith a metal catalyst plays a role in preserving heterogeneous acid catalysts in the citronellal conversion. from the perspective of green chemistry, some considerations are concluded. the onepotcitronellal conversion intomenthol ispreferrablecompared to two-step reactions, therefore the capability of catalysts for both cyclization and hydrogenation mechanisms is an important issue. the reusability of the catalyst that accommodates © 2021 the authors. page 175 of 180 yahya et. al. science and technology indonesia, 6 (2021) 166-180 its use in several cycles will contribute to minimizing waste and achieving a more economical process. the high-selective product, especially for a specied isomer is determined by the use of specic transition metal. the chemical and thermal stability of the catalyst 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of catalysts. organic & biomolecular chemistry, 14(11); 3130–3141 zhou, c. h., h. zhao, d. s. tong, l. m. wu, and w. h. yu (2013). recent advances in catalytic conversion of glycerol. catalysis reviews, 55(4); 369–453 © 2021 the authors. page 180 of 180 introduction citronella oil: source and extraction method citronellal conversion into isopulegol and menthol citronellal conversion into isopulegol clay-based heterogeneous catalysts future perspective acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper biogenic silica extracted from salacca leaf ash for salicylic acid adsorption is fatimah1*, faiha ulfiyani zaenuri1, lolita narulita doewandono1, amri yahya1, putwi widya citradewi1, suresh sagadevan2, won-chun oh3 1chemistry department, universitas islam indonesia, yogyakarta 55584, indonesia2nanotechnology & catalysis research center, university of malaya, kuala lumpur 50603, malaysia3department of advanced materials science and engineering, hanseo university, seosan-si, chungnam 356–706, south korea *corresponding author: isfatimah@uii.ac.id abstractthe extraction of biogenic silica from salacca leaf ash and its utilization as an adsorbent for salicylic acid has been successfullyconducted. the caustic extraction by refluxing the ash in naoh followed by slow titration using acid produced the silica gel. thesintering of the dried gel was varied at 300, 400, and 500°c to evaluate its physicochemical character for adsorption purposes.instrumental analysis of x-ray diffraction, scanning electron microscopy, gas sorption analysis, and fourier transform infraredspectroscopy (ftir) were employed. the kinetics of salicylic acid adsorption was investigated in a batch adsorption system andshowed the fitness of the adsorption with a pseudo-second-order kinetics. the isotherm studies revealed that salicylic acid adsorptionobeyed the langmuir model. at varied sintering temperatures, the highest adsorption capacity and affinity were achieved at atemperature of 500°c, due to the increasing specific surface area. the maximum adsorption capacity of 36.7 mg/g is comparablewith other work, but at less cost and synthesis process. the varied ph for adsorption is a suggestion that the neutral ph is the mostfeasible compared to the acidic and basic conditions. keywordsadsorption, biogenic silica, salicylic acid received: 29 june 2021, accepted: 18 september 2021 https://doi.org/10.26554/sti.2021.6.4.296-302 1. introduction the use of pharmaceuticals has signicantly increased in recent decades and later due to the current covid-19 pandemic. many drugs and pharmaceutically active compounds (pacs) areproduced inanextraordinarilysignicantamount. asaconsequence, pharmaceuticalwaste frompharmacyindustrial euent is also increased. besides, as a wastewaterconstituent, pacs are released during manufacturing and by disposal of unused or expired drugs. due to their bioactivities, the removal and handlingof manypacs must be appropriatelydesigned to minimize environmental contamination. in the form of wastewater, standard technologies used for chemicals-containing water remediation are used forpacs treatment. technologies based on advanced oxidation processes (aop), adsorption, and electrochemical oxidation are popular treatment methods (choi and shin, 2020; rakishev et al., 2021). the utilized low-cost materials, such as activated carbon, silica, and silica-alumina-based materials, have been explored to enhance the eectiveness of the pac adsorption process. high adsorptive capability, high ecacy, and good selectivity for removing a particular pharmaceutical compound are signicant features for selecting substances to remove pacs from the environment. salicylic acid (sa, c7h6o3) is a critical compound in pharmaceutical industries that is widely used for some other pharmaceutical compounds, such as acetylsalicylic acid (asa, c9h8o4) and atenolol (atl, c14h22n2o3). it is estimated that 40,000 tons of sa are consumed annually, and a high percentage of sa waste is released annually. the lack of specic sa treatment in wastewater management must cause adverse eects on the aquatic environment and biodiversity. moderate to high toxic eects are caused by environmental sa exposure to aquatic organisms, including oxidative stress and toxicity (freitas et al., 2020; gómez-oliván et al., 2014; nunes, 2019). sa is a common and widely used analgesic, antipyretic, and anti-inammatory drug, with an estimated annual consumption of 50–120 billion pills. exploring adsorption preparation for saadsorption will be critical in sustainable pharmaceutical industries (choi and shin, 2020). in many studies, the use of some sa adsorbents, such as natural zeolite (clinoptilolite), clays (bentonite and kaolin), activated carbon, and other polymeric resins (rakić et al., 2013; otero et al., 2004), is reported. silica and its building blocks, https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.296-302&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.296-302 fatimah et. al. science and technology indonesia, 6 (2021) 296-302 such as mcm-41, have also been reported to have high sa adsorption ecacy. the sa adsorption using silica-based materials is not only proposed for water remediation, but it is also used as preconcentration and drug loading in slow-release drug preparation. as part of the exploration of new and renewable materials from the perspective of green chemistry, the use of biogenic silica for this purpose was proposed to improve economic benets. the high potency of salacca leaf ash as a silica source was reported in previous works. the leavesare anagriculturalwaste produced in high amounts (silviana and bayu, 2018). the industrial utilization of salacca leaves as a source of biogenic silicaprovideseconomicvalueforthe industrialandagricultural sectors. based on this background, this research was aimed to use biogenic silica extraction from the ash of salacca leaves for sa adsorption. the potential content of silica in salacca leaf ash (sla) was revealed in previous investigations, but a more detailed study reporting its use as an sa adsorbent was not registered yet. therefore, biogenic silica extraction for sa adsorption, considering the extraction method for creating specic physicochemical characteristics as an adsorbent, was performed in this study. as an adopted extraction method from the standard method of biogenic silica extraction from other sources, this study was focused on the eect of the silica sintering process on its physicochemical characteristics and sa adsorption capability. 2. experimental section 2.1 materials salacca leaves were obtained from an agricultural area in the sleman district, yogyakarta, indonesia. chemicals used to extract silica from the salacca leaves consisted of naoh (97%), hcl (30%), sa (99%), and ammonium phosphate (99%). such substances were purchased from merck-millipore (germany) for pro analyst quality. 2.2 method the sla was obtained by pre-treatment, which consisted of cleaning them with water and then drying them in an oven at 60°c. later, the cleaned and dried leaves were incinerated in a mue furnace at 500°c under atmospheric conditions for 2 h. silica extraction was performed by reuxing 10 g of sla with 100 ml of 1 m naoh solution for 1 h. the result was ltered, and the ltrate was adjusted to ph 7.4 by dropping hcl 1 m until a white gel was produced. the precipitate was then kept in a hot air oven at 80°c overnight before sintering at varying temperatures: 300, 400, and 500°c. the samples were encoded as sio2-300, sio2-400, and sio2-500, respectively. the physicochemical characterization of the materials was performed using x-ray diraction (xrd), a gas sorption analyzer, a fourier transform infrared (ftir) spectrophotometry, and scanning electron microscope-energy dispersive x-ray spectrophotometry (sem-eds). a bruker d2 phase 2nd gen x-ray diractometer was employed in the analysis. a ni-ltered cu k𝛼 ray (_ = 1.54056 å) was used as a radiation source, and the measurements were carried out from 2\ = 10° to 80° at a rate of 0.4°/min. for the gas sorption analysis, a nova 1200 instrument was employed. for each analysis, the samples were degassed at 90ºc for 4 h before analysis. /a perkin-elmer ftir spectrophotometer was used in the analysis, and a phenom x instrument was used in the sem-eds analysis. the schematic representation of the silica extraction method is shown in figure 1. figure 1. schemtic representation of the method for biogenic silica extraction 2.3 adsorption experiment the sa adsorption experiments were conducted in a batch system using a bench horizontal shaker at 600 rpm. the sa analysis was performed on a uv-visible spectrophotometric analysis based on a standard curve. 3. results and discussion 3.1 material characterization figure 2. xrd pattern of derived sio2 the extracted silica at varying sintering temperatures was detectedthroughxrdmeasurementwiththereectionsshown in figure 2. a broad peak at a 2\ value of about 22° was exhibited by the xrd patterns in all samples. the broadness of these exhibited peaks are a conrmation that the synthesized biogenic nano silica samples were naturally amorphous © 2021 the authors. page 297 of 302 fatimah et. al. science and technology indonesia, 6 (2021) 296-302 and were tted with the jcpds data le no: jcpds 46-1045 (chun et al., 2020; fatimah et al., 2019; jaafari et al., 2020). figure 3. sem prole of derived sio2 samples ahigherpeakintensityandtheremovalofsomeotherpeaks reecting the impurities in the sio2-300 sample were caused bythe sintering. however, the sio2 content was not inuenced by the sintering temperature in the edx analysis, suggesting that the impurities corresponded to silicious materials. the increasing intensity and the broad peak shift at the lower angle were attributed to the increasing pore size homogeneity caused by h2o removal and dehydration at increasing temperatures. a similar eect was observed in silica extraction from rice husk ash and the characteristics of silica forms (alyosef et al., 2013; prasad and pandey, 2012). the determined sio2 content was around 98.7–98.8% wt. the removal of the exhibited minor peaksanddehydrationat thehighertemperaturewasconrmed by the surface morphology change, as shown in figure 3. more homogeneous particle sizes and a more opening surface were found for sio2-500. the surface morphology proles of the samples are in agreement with the surface prole data obtained by gas sorption analysis. table 1. surface parameters and sio2 content of materials parameter sio2-300 sio2-400 sio2-500 specic surface area 58.9 89.7 92.9(m2/g) pore radius (å) 10.9 12.2 11.8 pore volume (cc/g) 5.26 x10−3 23.1 x10−3 25.6 x10−3 sio2 content (% wt) 98.7 98.7 98.8 the sintering temperature eect on the surface was also identied from the change of specic surface area, and pore distribution, shown in figure 4. the calculated parameters are shown in table 1. the specic surface area of 58.9 m2/g was demonstrated by the prepared sio2. after the sintering process, it was increased to 89.7 m2/g and 92.9 m2/g at 300°c and 500°c, respectively. the increased specic surface area is consistent with the adsorption-desorption prole figure 4 and the pore size distribution figure 4, reecting the improvement inadsorptioncapabilityatall thep/p° ranges. themicroporous domination, which is characteristic of silica and nano silica extracted from biogenic sources, was implied by the isotherm pattern and pore distribution plots. figure 4. adsorption-desorption isotherm of sio2 samples (a), pore distribution curve of sio2 samples (b) the comparison of silica content and the specic surface area from various silica sources are shown in table 2. in other sources in which a high specic surface area (more than 100 m2/g) was exhibited, such as oat and rice husks, the specic surface area of sio2 obtained in this research was relatively lower (more than 99% wt) with high specic surface area (more than 100 m2/g), but the silica content is relatively high (98.7% wt). the ftir spectra comparison is shown in figure 5 shows. there was no signicant dierence among the materials. the -oh absorptions were identied at a wavenumber of around 3388.9–3394.1 cm−1, and the lower wavenumber (3388.9 cm−1) corresponded to sio2-300. the band was unidentied at a higher calcination temperature, indicating the reduced amount of -oh functional group on the surface caused by the heating and dehydration process. the absorption bands at 1633–1638 cm−1 were representations of the asymmetric stretchingvibrationssi-o-si stretchingvibration, followingthe si-o symmetric stretching vibration identied at a wavenumber of around 1387 cm−1. other absorption bands around 430–460 cm−1 are indications of si-o bending vibrations. © 2021 the authors. page 298 of 302 fatimah et. al. science and technology indonesia, 6 (2021) 296-302 table 2. comparison of sio2 specic surface area and content obtained from various sources source silica content specic surface reference(%wt) area (m2/g) rice husk 97.7 313 (alyosef et al., 2013) sugarcane baggase 87.6 15 (alyosef et al., 2013) oat husk 99.1 248 (maseko et al., 2021) 91.6 301 (maseko et al., 2021) ground nut shell nd 0.89 (peerzada and chidambaram, 2020) oat husk 94.1–94.3 124–129 (mattos et al., 2016) horsetail 98.2 393 (mattos et al., 2016) bamboo leaves ash 99.1 428 (rangaraj and venkatachalam, 2017) salacca leaves ash 98.7 58.9 this work figure 5. ftir spectra of materials 3.2 adsorption of sa the sa adsorption kinetics were evaluated by referring to the pseudo-rst-order and pseudo-second-order by the following equations 1– 2 : ln(qe − qt) = lnqe − kt (1) t qt = 1 k2q2e + t qe (2) where, qt (mg/g) is the amount of adsorbed metal ions at the time of t, qe (mg/g) is adsorption capacity, k (min−1) is the rst-orderrate constant, and k2 (g/mgmin) is the second-order rate constant of adsorption (min−1) (lee et al., 2018; zou et al., 2018). sa adsorption kinetics are shown by the curve in figure 6. insignicant adsorption capabilities were exhibited by the sio2-400 and sio2-500 with the varied sintering temperature. nonetheless, such numbers were still higher than those for sio2-300. the higher r2 values for the pseudo-second-order kinetics model for all adsorbents are suggestions for the second-order figure 6. kinetics of sa adsorption on sio2 samples [initial sa concentration = 20 mg/l, temperature = 25°c, ph = 7] tness. the kinetics order represented the dependency of the adsorption mechanism concerning both the sa concentration and the available adsorption sites. sa adsorption was also obtained using polymeric and activated carbon in a similar kinetics study (câmara and neto, 2008). given the chemical sa structure, which contains the hydroxyl functional groups and the aromatic ring, hydrogen bonding and electrostatic interaction are the main mechanisms besides the possible molecular sieving mechanism. given the silica surface interaction with some other aromatic compounds, the net negative charge of the aromatic ring is electrostatically bound with the oxygen on the silica surface. meanwhile, the hydrogen atom interacts with the surface via hydrogen bonding (sadhu et al., 2014; yuan et al., 2019). the schematic representation of the adsorption mechanism is shown in figure 6. the adsorption isotherm was performed by modeling the adsorption data using the langmuir and freundlich models to studythe interactionbetweentheadsorbateandadsorbent. the freundlich and langmuir model equations are represented in the following equations 3–4: © 2021 the authors. page 299 of 302 fatimah et. al. science and technology indonesia, 6 (2021) 296-302 table 3. the calculated langmuir and fruendlich isotherm parameters adsorbent langmuir freundlich qm (mg/g) kl (l/mg) rl r 2 kf (l/g) 1/n r 2 sio2-300 26.58 2.11 0.93 0.997 1.32 0.28 0.931 sio2-400 26.51 1.86 0.93 0.997 1.33 0.29 0.916 sio2-500 34.91 8.21 0.8 0.981 1.49 0.39 0.945 qe = kfc 1/n e (3) qe = qmklce 1 + klce (4) where qe (mg/g) is the equilibrium adsorption capacity of the adsorbent, ce (mg/l) is the concentration of adsorbate in equilibrium, qm (mg/g) is the maximum adsorptive capacity of the adsorbent, kf is the freundlich constant related to the adsorption-desorption equilibrium of adsorption capacity, n is the freundlich constant related to the adsorption intensity, and kl (l/mg) is the langmuir constant related to the adsorption energy (dada et al., 2012). the equilibrium parameter from the langmuir isotherm, rl, is represented as follows equation 5 : rl = 1 1 + klqm (5) figure 7. linear langmuir model plot of sa adsorption by sio2 samples the calculated parameters are shown in table 3. from the values, it was observed that both models applied well for sa adsorption in all sio2 samples. however, the langmuir model was better based on the nearness to the unity of the r2 values. this nding is also shown in figure 7, where the tness of adsorption data with the langmuir model was implied. a typical surface diusion control of the adsorption by a homogeneous surface was demonstrated by the tness of the langmuir model (câmara and neto, 2008). the role of chemisorption on the silica surface was validated by the 1/n values from the freundlich isotherm that was laid at 1/n < 1, and by the langmuir model, the rl values ranged from 0 < rl < 1 (0.80–0.94) for all adsorbents. in previous similar works, it was stated that the rl values = 0, 0 < rl < 1, rl = 1, and rl > 1 are indicative of irreversible, favorable, linear, and unfavorable adsorption, respectively. the sa adsorption from all the samples in this work was favorable (yagub et al., 2014). table 4. comparison of sa adsorption capacity using various adsorbents adsorbent adsorption referencecapacity (mg/g) zeolite 8.97 (rakić et al., 2013) zeolite 2.3 (cabrera-lafaurie et al., 2014) bentonite 34.5 (rakishev et al., 2021) activated carbon 4.2 (rakishev et al., 2021) non-imprinted 63.5 (xu et al., 2021) polymer (nip) hexadecyltrimethy 42 (choi and shin, 2020)lammonium-modied montmorillonite molecularly imprinted 30.42 (rahangdale et al., 2016) chitosan graphene 63.66 (lee et al., 2018) molecularly imprinted 30.3 (rahangdale et al., 2016) polymer si-500 36.7 this work from the varied sintering temperature, the sio2-500 was suggested by all parameters from both isotherms to have the highest anity for sa adsorption. the adsorption anity was in linewiththespecicsurfaceareadata, indicatingthatahigher sintering temperature produced a higher specic surface area. based on the adsorption capability data and the comparison with other adsorbents presented in table 4, the sa adsorption © 2021 the authors. page 300 of 302 fatimah et. al. science and technology indonesia, 6 (2021) 296-302 by the biogenic silica extracted in this research was comparable to that obtained from bentonite and was even higher than that obtained from zeolite. with a capacity of 36.7 mg/g, the sio2-500 sample give higher value compared to molecularly imprinted polymer and molecularly imprinted chitosan, even though it is still lower compared to other adsorbents. it is important to be noted that the synthesis method in this work is by the lower cost. 3.3 eect of ph figure 8. eect of ph on sa adsorption capacity by the materials the study of the eect of ph on adsorption capability is of critical importance for the application purpose. the varying ph of 4, 7, and 9 on the sa adsorbed percentage is shown in figure 8. there was optimum adsorption at the neutral (ph = 7) from these values, which was identied by the highest sa adsorption percentage for all sio2 samples. the lower adsorption capacity at a low ph (ph = 4) is attributed to the protonic condition of the silica surface. therefore, there was a repulsive force on the sa surface. contrarily, the negative charge of the surface was led by the basic condition (ph = 10), according to equation 6, as follows: sioh + oh– > sio– + h2o (6) repulsive force may occur due to the hydroxyl group in sa (mustafa et al., 2003). the adsorption mechanism is suggested to be intensely dependent on the surface charge by the results. this nding is characteristic of adsorption, with no other mechanism, such as covalent, ligan-metal ion, or 𝜋-𝜋 interaction. 4. conclusions in this study, biogenic silica was successfully extracted from salacca leaf ash, and the silica samples were shown to be eective adsorbents for salicylic acid from an aqueous solution. the increasing specic surface area and the increasing temperature were reected by the varying sintering temperatures, which aected the increasing adsorption capacity. the homogeneous surface of silica was exhibited, as suggested by the tness of the adsorption kinetics to the langmuir isotherm model. the resultsof this researchrepresentedthatsalacca 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6192–6205 yagub, m., t. sen, s. afroze, and h. ang (2014). dye and its removal from aqueous solution by adsorption: a review. adv colloid interfac 209: 172–184 yuan, n., h. cai, t. liu, q. huang, and x. zhang (2019). adsorptive removal of methylene blue from aqueous solution using coal y ash-derived mesoporous silica material. adsorption science & technology, 37(3-4); 333–348 zou, c., j. liang, w. jiang, y. guan, and y. zhang (2018). adsorption behavior of magnetic bentonite for removing hg (ii) from aqueous solutions. rsc advances, 8(48); 27587– 27595 © 2021 the authors. page 302 of 302 introduction experimental section materials method adsorption experiment results and discussion material characterization adsorption of sa effect of ph conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 4, october 2018 research paper characterization and optimization of capryol-90, polysorbate-80, and peg-400 proportion in mefenamic acid self nanoemulsifying drug delivery system (snedds) with simplex-lattice-design mardiyanto1*, najma annuria fithri1, martina tandri1 1department of pharmacy faculty of mathematics and natural science sriwijaya university *corresponding author: mardiyantounsri@gmail.com abstract mefenamic acid as pain relief drug belongs to the biopharmaceutics classification system (bcs) class ii which is practically insoluble in water causing extremely low dissolution in gastrointestinal tract. the selfnanoemulsifying drug delivery system (snedds) is a new innovation pharmaceutical dosage form that has effectively known to increase solubilization of hydrophobic drug in polar solvent. in this study the capryol-90 was selected as oil phase in snedds as it showed maximal solubility of mefenamic acid (20 mg/ml). combination of polysorbate-80 and peg-400 as a generally regarded as safe (gras) excipient were used as surfactant and co-surfactant in snedds due to its high hlb property that can increase mefenamic acid solubility in water. the ternary phase diagram of capryol-90, polysorbate-80, and peg-400 was constructed in advance to obtain the component concentration of spontaneous nanoemulsion region. model simplex-lattice-design cooperated in design-expert® was used to define snedds mefenamic acid formula. optimized mefenamic acid snedds formula consisted of 20% capryol-90, 31.62% polysorbate-80, and 48.38% peg-400. characterization study of optimized mefenamic acid snedds formula showed improvement of drug content (102.820 ± 4.950)%, emulsification time (421.015 ± 1.290) second, and viscosity (0.927 ± 0.017) mm2/s 30°c. one way anova statistical analysis result of optimal formula snedds (105.210 ± 4.425)% of drug content, commercial generic caplet (0.917 ± 0.094)%, and mefenamic acid powder capsule (10.446 ± 0,333)% gave significant value (sig*) below than 0.05. optimal formula proved that snedds can significantly increase mefenamic acid dissolution of ph 7.4 (ileum fluid). the optimal formula of mefenamic acid snedds successfully formed an uniformity droplet size (pdi 0.18) with mean size 241.9 nm and the surface charge has a value of -16.5 mv respectively. keywords mefenamic acid, snedds, capryol-90, polysorbate-80, peg-400 received: 1 september 2018, accepted: 30 september 2018 https://doi.org/10.26554/sti.2018.3.4.164-172 1. introduction mefenamic acid as antiin�ammatory non steroid (ains) drug is used for analgesic to relief headache, toothache, dysmenorrhea, rheumatoid arthritis, osteoarthritis, muscle pain, traumatic and post operation (mudalip et al., 2013). mefenamic acid already known asthe most traded drug in middle-income countries and in high-income countries. this achievement shows the level of its consumption occurring in the community (mcgettigan and henry, 2013). high oral dosage of commercial mefenamic acid (500 mg) can increase the probability of side e�ect such as cardiovascular thrombosis, stroke, congestive heart failure, udem, ulceration, bleeding, and gastrointestinal perforation. this concern caused by the low solubility of mefenamic acid in instestinal �uid (bcs class ii), therefore it has poor bioavailability and absorption. based on its properties, fda (2008) recommends the use of mefenamic acid the lowest e�ective dose (mudalip et al., 2013). nanosized particles (± 200 nm) of drug has been shown to improve the absorption of drugs so the usage dose can be reduce without decreasing the e�cacy (mardiyanto, 2013; yoo et al., 2010). the self nano emulsifying drug delivery system (snedds) is one of the nanoparticles dosage form which can increase drug solubility and maximize the absorption in gastrointestinal tract by emulsi�cation mechanism (n.a et al., 2017; sutradhar and amin, 2013). the succeed level of emulsi�cation is quite high because of the spontaneous emulsion forming of oil in water (o/w) only need weak agitation (gursoy and benita, 2004). the snedds composition used in this study are capryol90 as dispersed phase, polysorbate-80 as surfactant, and peghttps://doi.org/10.26554/sti.2018.3.4.164-172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 400 as co-surfactant. the hydrocarbon chain of capryol-90 can dissolve the lipophilic drug better and make it not easily oxidized(anton and vandamme, 2009). the high hlb (hydrophilic lipophilic balance) of polysorbate-80 (15.0) can increase the hydrophilicity, dissolution, and di�usion of mefenamic acid in gastrointestinal tract so that the absorption process can be more e�ective (chen et al., 2018; shahba et al., 2012). peg-400 is used for reducing the amount of polysorbate80 usage to maintain nanoemulsion droplet size does not to be large, hence the paracellular di�usion and dissolution can increase (sriamornsak et al., 2015). software design expert® version 10 (dx®10) is used for minimazing the trial of snedds optimized formula study which has the best droplet size and dissolution. simplex lattice design (sld) is chosen as the appropriate optimization model for 3 component formulation. sld model is very appropriate for this study because it can calculate the response value of experiment total to the e�ect of di�erences in the amount of material on each formula (armstrong, 2006). this study is expected to determine the optimized formula of snedds mefenamic acid that can improve the absorption of mefenamic acid. 2. experimental section 2.1 materials the materials which used in this study were mefenamic acid (dexa medica), capryol (tm 90 type nf) (gattefosse), polysorbate80 (gattefosse), peg-400 (gattefosse), ethanol p.a (merck®), naoh p.a. (merck®), kh2po4 (p�zer®), methanol p.a. (merck®), anhydrous ch3cooh (aps), anhydrous ch3coona (merck®), and aquabidest (ipha laboratories). 2.2 methods 2.3 determination mefenamic acid solubility in capryol90 the solubility test was performed by dissolving mefenamic acid (2.4; 2.6; 3.4; 10; dan 20 mg) in 0.5 ml capryol-90 in a vial. the mixture was then stirred with a magnetic strirrer in 150 rpm for 15 minutes and then sonicated (bath-sonicator covaris s220) for 45 minutes. formation of the precipitate at each mixture was observed to determine the maximum solubility of mefenamic acid in capryol-90 (sriamornsak et al., 2015). 2.4 ternary phase diagram construction capryol-90 (0-100% v/v), peg-400 (0-100% v/v), and polysorbate80 (0-100% v/v) as continues oil phase, surfactan, and cosurfactan were combined into 21 ternary phase. mixture of capryol-90, peg-400, and polysorbate-80 were stirred (ika47) with magnetic stirrer 300 rpm at room temperature for 15 minutes (taha et al., 2004). 2.5 self-emulsi�cation and precipitation ternary phase diagram study self-emulsi�cation of 21 ternary phase was studied by slowly dropping of 80 µl ternary phase solution into 50 ml aquadest in beaker glass (1:625) while stirring on magnetic stirrer 100 rpm. self-emulsi�cation ability of 21 ternary phases were assessed after all components were dispersed homogeneously through the color, clarity, and the presence of globules in emulsion. precipitation parameter, such as clarity, separation phase, and the presence of precipitation or globule were observed after 24 hours self-emulsi�cation study with light observation (craig, 1995). 2.6 ratio component snedds mefenamic acid composition ratio of capryol-90, polysorbate-80, and peg400 was determined using simplex lattice design method software dx®10. the sum of three components was 1 with low value 0 while high value was 1 (table 1). it was replicated 3 times so the selected model was quadratic. there were 3 responses result that was entered in dx®10 to determine optimized formula; drug content, emulsi�cation timefor 13 formulas. table 1. proportion of capryol-90; polysorbate-80; peg-400 level proportion (%) capryol-90 polysorbate-80 peg-400 low 20 20 40 high 40 40 60 2.7 snedds mefenamic acid preparation mefenamic acid snedds (table 2) was prepared by dissolving mefenamic acid in capryol-90 on magnetic stirrer 150 rpm, then it was sonicated for 45 minutes at room temperature. peg-400 was added and the mixture was resonicated for 45 minutes. at the last, polysorbate-80 was added and the mixture using bath sonicator for 10 minutes to obtain the yellowish solution. 2.8 snedds characterization 2.8.1 drug content mefena�c acid snedds of 10 µl was diluted in 5 ml metanol p.a then the absorbance was measured by spectrophotometer (fischer scienti�c evolution-201/220)uv-vis in λmax 285 nm (yadav et al., 2014). the process was replicated in three times. 2.8.2 emulsi�cation time and precipitation emulsi�cation time was observed at room temperature. snedds of 20 µl was diluted in 12.5 ml aquadest with magnetic stirrer 150 rpm until snedds (clear solution or milky without globul of oil) was formed. precipitation using centrifuge (labds 1001sd)parameter; such as clarity and phase stability after 24 hours, was observed under the light (24 hours start from the last stirred) (craig, 1995; pouton, 1997). © 2018 the authors. page 165 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 table 2. formula snedds mefenamic acid formula mef ac (mg) capryol (ml) polysornat80 (ml) peg-400 (ml) run 1 40 20,00 40,00 40,00 run 2 40 30,00 30,00 40,00 run 3 40 40,00 20,00 40,00 run 4 40 23,33 33,33 43,33 run 5 40 20,00 40,00 40,00 run 6 40 20,00 30,00 50,00 run 7 40 30,00 20,00 50,00 run 8 40 23,33 23,33 53,33 run 9 40 20,00 20,00 60,00 run 10 40 20,00 20,00 60,00 run 11 40 40,00 20,00 40,00 run 12 40 26,67 26,67 26,67 run 13 40 33,33 23,33 43,33 2.8.3 formula optimization snedds component of 13 formulas was optimized using sld method in dx®10was based on the result of 3 responses with speci�c criteria arrangement. combination of snedds component that had the highest desirability in solution was chosen as optimized formula. 2.8.4 study response snedds mefenamic acid response test point was re-studied to 3 batches of the snedds optimized formula (table 2) along with in vitro dissolution study, diameter measurement, pdi, and zeta potential of snedds globules. drug content measurement of the �nal physical stability sample was evaluated furthermore. 2.8.5 in vitro dissolution dissolution study using dissolution equipment (pharmatest ptsw-d62) of snedds, capsule, and generic caplet of mefenamic acid were studied in triplo. transparent hard-capsule of number 0 (0.82 ml) was �lled with 0.6 ml snedds of optimized formula while capsule number 0 (1,2 ml ≈ 600 mg) was �lled with 500 mg pure mefenamic acid. capsule contain snedds, pure mefenamic acid, and generic caplet were put into 500 ml bu�ered sif ph 7.4 at 37 ± 3°c with rotation speed 100 rpm for 60 minutes. aliquot (5 ml) was taken in minutes of 0; 5;10; 15; 20; 25; 30; 35; 40; 50 and 60. caplet and capsule pure drug aliquot was �ltered using whatmann �lter 0.22 µm. aliquot absorbance was measured with spectrophotometer uv-vis in λmax 285 nm (sriamornsak et al., 2015). 2.8.6 diameter, pdi, and zeta potensial snedds globules snedds mefenamic acid 500 µl was dropped into 5 ml aquabidest (emulsion 1:10) on a magnnetic stirrer 150 rpm, then stirred for 1 hour. emulsion of 5 ml was poured into microcuvette of particles size analyzer (horiba-sz100) to measure the size, pdi, and zeta potential snedds droplet (mardiyanto, 2013). 2.9 statistic analysis 2.9.1 optimized formula di�erences bipolysorbate result study of drug content, and emulsi�cation time of snedds optimized formula and dx®10 prediction was analyzed using one sample t-test method in minitab 17 statistical® software. analysis result was indicated to be signi�cantly di�erent if p-value< 0.05. 2.9.2 in vitro dissolution study % release and de60 di�erences bipolysorbate snedds capsule, pure drug capsule, and generic caplet was analyzed using one-way anova method in software spss®20. comparison post hoc result of each group can be seen from tukey dan lsd report. analysis result wasindicated to be signi�cantly di�erent if sig value <0.05. 3. results and discussion 3.1 determination of mefenamic acid solubility in capryol90 the maximum solubility of mefenamic acid in oil phase (capryol90), surfactant (polysorbate-80), and co-surfactant (peg-400) were used as the basis for determination the amount of mefenamic acid that can be added in the snedds formula. the phase plays important role to maintain active drugs and remain in dissolved state in emulsion, therefore it was important to know the solubility of mefenamic acid in capryol-90 (sriamornsak et al., 2015). based on the former study result, capryol-90 was the best oil phase to dissolve mefenamic acid (20 mg/ml) compared with clove oil (9.95 mg/ml) (based on study conducted by sriamornsak et al. (2015). it was caused by the natural surfactant properties of capryol-90 medium chain that can dissolve more hydrophobic substances (constantinides, 1995; karim et al., 1994). © 2018 the authors. page 166 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 3.2 selection of snedds mefenamic acid component selection of oil phase, surfactant, and co-surfactant become critical point to increase the active drug solubility and drug loading in self emulsifying dosage form. selected components were preferable having maximum solubility.miscibility towards all components that contained in the dosage form was to produce a stable formula. capryol-90 was chosen as oil phase because it had solubility ± 2 times than clove oil. amphiphilic nature of hydroxy group capryol-90 had natural surfactant characteristic. this bene�t can reduce the amount of surfactant used so it also can minimize the toxicity risk as result of high concentration use of surfactant (jaiswal et al., 2014). besides that, clove oil can irritate the mucus membrane, so capryol-90 �nally was chosen (sriamornsak et al., 2015). another bene�t of using capryol-90 as oil phase is its biodegradable properties and ability to form nanoemulsion. polysorbate80 is chosen as surfactant because it has high hlb (15.0) so it can dissolve mefenamic acid e�ciently. polysorbate-80 is safe for human consumption because its non-ionic characteristic has low toxicity. besides that, hidrophilic characteristic of polysorbate-80 is very appropriate with watery condition of gastric and intestine that had much hydrophilic �uid (sriamornsak et al., 2015). although polysorbate-80 (31.94 mg/ml) has lower solubility than polysorbate-20 (36.96 mg/ml) (sriamornsak et al., 2015) but polysorbate-80 is more selected than polysorbate-20 according to the result study of lornoxicam snedds shows that the need of smix (surfactant and cosurfactant) toform capryol-90 into emulsion is reduced by the use of polysorbate-80 as surfactant than polysorbate-20. this result showed that the ability of polysorbate-80 to form capryol-90 into emulsion state was greater than polysorbate20. combination of polysorbate-80-capryol-90, polysorbate80-transcutol and polysorbate-80-peg-400 is categorized as gras (generally regarded as safe) (fda ll wl 1349) (jaiswal et al., 2014). the reason to choose peg-400 (29.79 mg/ml) than transcutol® hp (38.76 mg/ml) (sriamornsak et al., 2015) was based on snedds hydrochlortiazid study by yadav et al. (2014) that showed the necessary amount of surfactant to expand the nanoemulsion region in smix of peg-400 and polysorbate-80 was less than using smix transcutol and polysorbate-80. using polysor-bate 80 in high concentration can make the size of globul bigger, therefore peg-400 was chosen as co-surfactant snedds. based on this data, capryol90, polysorbate-80, and peg-400 were chosen as component snedds mefenamic acid to be studied furthermore. 3.3 determination nanoemulsion and ternary phase diagram of mefenamic acid snedds proportion of capryol-90, polysorbate-80, and peg-400 that able to form spontaneous nanoemulsion was determined by preparationof 21 combination of ternary phase diagram. ability of forming nanoemulsion spontaneously was assessed after aquadest was added drop by drop into ternary phase solution. this assessment was designed like that because emulsion will only be formed if one of the emulsion phases had dispersed into small droplet form. nanoemulsion of ternary phase has just formed spontaneously (blue and green circle) in figure 1 if minimal proportion of polysorbate-80 is 20%. the increase proportion of polysorbate-80 and peg-400 can make the emulsion more clear or transparent because of the adsorption surfactant and co-surfactant on oil and water surface reduce the tension surface energy and cohesion force in emulsion system so emulsion became more stable (sriamornsak et al., 2015). snedds solution become clear because nanoemulsion globul was < 100 nm, meanwhile the turbid snedds was formed because the globule size is > 10 µm (porter et al., 2007). the increase of capryol-90 proportion caused oil globules can not be dispersed but coalesced on the surface. this was happened because hlb polysorbate-80 and peg-400 didn’t comply with the hlb requirement. as the result, polar and non polar group of polysorbate-80 and peg-400 as capryol90 and aquadest as illustrated in figure 3, the joint was not available enough. this a�ects the stability of dispersion system and then the unstable emulsion was formed (azeem et al., 2009). component proportion that form nanoemulsion region in 13 snedds formulas determination (table 2) was rearranged in order to comply the total component of optimized sld model into 100% so the software showed the combination proportion of nanoemulsion component which then will be studied. precipitation was observed to investigate the risk of precipitation of capryol-90 after dispersed in water (mohsin et al., 2009). precipitation of capryol-90 a�ects the reduction of the absorbed mefenamic acid amount. 21 ternary phase stability show that at least there is 80% ternary phase component in dissolve state during 24 hours (shahba et al., 2012). 3.4 visual observation of snedds mefenamic acid formulas snedds of 13 and optimized formula produced slightly viscous yellow transparent solution without precipitation with slightly coconut odor (figure 2). the yellow color of snedds became intense with increasing the amount of polysorbate-80 because polysorbate-80 had concentrated yellow color (rowe et al., 2009). 3.5 drug content measurement drug content was measured to know the mefenamic acid concentration in snedds. this data was used to determine the usage dose (tzafriri et al., 2012). methanol was chosen as snedds solvent in drug content measurement because methanol was known as universal solvent that had ability to extract whole mefenamic acid that covered inside globul (cole, 2003). results of snedds drug content had good precision because their rsd (table 3) > 7.3 % so % drug content 13 formulas can be continued at dx®10 analysis (aoac intenational, 2012). result of % drug content snedds mefenamic acid (table 3) showed that run 13 (93.04 %) has the highest % drug © 2018 the authors. page 167 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 figure 1. diagram of ternary phase capryol90, polysornate80 and peg400 figure 2. the image of snedds mefenamic acid content while run 12 (79.80 %) was the lowest and did not meet the requirement because exceeded the minimum ich limit (2005) (80 120%). this causes the therapeutic did not to be achieved thepain relief e�ect (abraham et al., 2013). the snedds component was thought to play role in in�uencing the drug content, therefore the analysis of the e�ect of snedds components on drug content using dx®10 was discussed further. special quartic was chosen by dx as analytical model because p-value lack of �t of this model was most unsigni�cant (0.3120 > 0.10). the combination of a2bc, ab, abc2 had signi�cant e�ect on % drug content because the factor had pvalue < 0.05. the in�uence of a2bc > ab >abc2 because the relationship bipolysorbate p-value and the factor e�ect was opposite, so lower p-value make the greater factor e�ect. dx®10 analysis formed 3 equations which express the in�uence of each component to % drug content (stat-ease, 2016). y = 88,09 a + 83,98 b + 86,5 c 26 ab + 3,34 ac + 18,38 bc + 879,82 a2 bc – 194,16 ab2 c – 511,45 abc2 description: y = % drug content a = capryol-90 proportion b = polysorbate-80 proportion c = peg-400 proportion florentia (2013) reported that positive coe�cient a2bc value give synergic e�ect, while the negative ab dan abc2 value showed antagonist e�ect to the response. more double combination of capryol-90 (a2bc) can increase % drug content because hydrophobic property of capryol-90 causes mefenamic acid easier to dissolve. ab and abc2 factors decrease % drug content because the non-polar carbon chain of polysorbate80 and peg-400 caused capryol-90 to break their bond with mefenamic acid, hence the solubility of mefenamic acid is decreased. 3.6 emulsi�cation time and precipitation observation self-emulsi�cation ability become the main point in snedds evaluation because bioavailability and oral absorption e�ciency of practically insoluble drug can be increased by self-emulsi�cation process that generate �ne dispersion and micellar to avoid drug precipitation and recrystallization (pouton, 1997). the formula indicated to have good self-nanoemulsi�cation ability if emulsion components (capryol-90, polysorbate-80, and peg400) can completely disperse in short time when mixed with aqueous phase with a little help from low agitationof peristaltic activity (porter et al., 2007; parmar et al., 2011). © 2018 the authors. page 168 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 figure 3. the formation of snedds mefenamic acid globul during self-nanoemulsi�cation 3.7 observation of physical stability physical stability was carried out to determine the maximum storage duration which can lead to the separation of emulsion (creaming or cracking) phases. the test results show if snedds mefenamic acid had good stability because for 3 cycles heating cooling does not show phase separation, viscosity change and snedds color. this proves the statement of (hintzen et al., 2014) and (weerapol et al., 2014) if the snedds dosage form has good physicochemical stability. this was because the mefenamic acid dissolving well in the snedds component has improved the stability of the preparation (parmar et al., 2011). capryol-90 which has maximum solubility to mefenamic acid and the use of polysorbate-80 30-60% (w/w) can dissolve more mefenamic acid so can minimize the mefenamic acid precipitation. peg-400 as co-surfactant according to jaiswal et al. (2014) can dissolve hydrophilic surfaces and drugs in the oil phase so can help maintain snedds stability. 3.8 response of the snedds mefenamic acid optimum formula run 6 of formulas were selected as representatives of 13 formulas because they have snedds component proportions that resemble the proportion of the optimum formula. the drug content response of the optimum formula was di�erent enough while the viscosity, emulsi�cation time, ph snedds (5.5) depends on capryol-90, polysorbate-80, and peg400 compositions so that the di�erence in measurement results of the optimum formula and formula was not much di�erent. the physical stability of optimum formula snedds was physically stable because it did not show separating emulsion phase or the deposition of mefenamic acid during the 3 heating cooling cycles test. however, the result of stability test determination showed that there was degradation of mefenamic acid from 8.2 ppm to 7.0 ppm. mefenamic acid degradation is estimated to occur due to increasing temperature extremely in the heating cooling process. (martin and bustamante, 1993) describes if the rate of degradation reaction can increase 2-3 times every 10°c temperature increase due to increased kinetic energy of the molecule resulting in the decomposition of the molecular complex of mefenamic acid. 3.9 statistical analysis of drug content, and emulsi�cation time of optimum formula snedds precision of 3 responses test method has suitable precision because rsd (4,819%) <7.3%. the test results of the di�erence of one sample t-test with α 0.05 indicate if the drug content, emulsi�cation time, and viscosity of predicted value dx®10 di�ered signi�cantly (p-value <0.05 on the experimental results (table 4). this di�erence was expected to occur because the dx®10 program did not relevant to the e�ects of variations in test conditions (such as environmental conditions, testing tools, human error) in predicting response (stat-ease, 2016). 3.10 in vitro dissolution dissolution tests were performed to determine the process of release of mefenamic acid from snedds dosage form, generic caplets, and pure mefenamic acid capsules. dissolution becomes the most important characteristic in testing the mefenamic acid snedds response because the faster the dissolution is, the more likely it is to minimize the elimination caused by the �rst pass e�ect. this may increase the amount of absorbed mefenamic acid so that the analgesic e�ects of mefenamic acid can be felt only by the low dose of mefenamic acid. the rapid increase in the release of cumulative mefenamic acid of snedds in minute-5 (figure 4) occurred due to the rapid formation of spontaneous nanoemulsion which increased the solubility of mefenamic acid in water. © 2018 the authors. page 169 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 table 3. response test result of 13 formulas snedds mefenamic acid formula average rsd average rsddrug content emulsi�cation time (%) ± sd (second) ±sd run 1 85.01 ± 0.87 3.137 165.58 ± 0,72 0.434 run 2 79.80 ± 0.59 1.018 900 ± 0 0 run 3 86.84 ± 2.72 3.364 900 ± 0 0 run 4 82.29 ± 2.48 4.944 900 ± 0 0 run 5 83.08 ± 0.06 0.742 166.52 ± 1,35 0.81 run 6 90.10 ± 0.70 5.509 457.51 ± 3,64 0.795 run 7 88.39 ± 2.91 2.964 900 ± 0 0 run 8 83.06 ± 3.45 4.154 900± 0 0 run 9 87.49 ± 2.94 0.076 720.35 ± 2,40 0.333 run 10 85.65 ± 4.72 3.296 732.75 ± 0,25 0.034 run 11 89.46 ± 4.42 3.01 900 ± 0 0 run 12 89.04 ± 1.04 1.169 900 ± 0 0 run 13 93.04 ± 2.76 0.773 900 ± 0 0 explanation: run 5, 10 and 11 is replicate formula of run 1, 9, and 3 table 4. the results of the statistical analysis of predictive value of dx®10 of formula snedds evaluation dx®10 experiment p-valueprediction (n=3) ± sd drug content (%) 89,512 102,820 ± 4,950 0,043 emulsi�cation time (second) 428,933 421,015 ± 1,290 0,009 viscosity (mm2/s 30ºc) 0,868 0,927 ± 0,017 0,026 figure 4. the dissolution pro�le of snedds mefenamic acid the result of anova% release of mefenamic acid and de60 from snedds, caplet, and pure capsule showed signi�cant dissolution (sig. <0.05). post hoc lsd and tukey in the minute-10 (when% release 100%) and the minute-60 (�nal stage of dissolution) showed if%release bipolysorbate dosage form also di�erent signi�cantly (sig. <0.05). the de60 snedds value was greater than pure capsules and commercial generic caplets because the % release snedds has been able to reach 109% at the minute-10. the anova results and the dissolution graph (figure 4) show that snedds able to improve the mefenamic acid dissolution signi�cantly. kinetics of mefenamic acid release from snedds, caplet, or pure capsule follows order 0 so that the rate of release of mefenamic acid was not a�ected by concentration but by the solubility of mefenamic acid to dissolution media (martin and bustamante, 1993). this was because the di�culty in dissolving mefenamic acid in the sif medium (0.01 mg/ml) became strength the stagnant di�usion layer to eliminate the sink conditions during the test. the kh value of the higuchi kinetics model ≥ 1 illustrates the release of mefenamic acid from snedds, generic capsules and caplets also undergoing di�usion processes (gursoy and benita, 2004). the mefenamic acid nanoemulsion formation increases solubility in the sif so that snedds could narrow the distance of the stagnant di�usion layer thus accelerating the dissolution of mefenamic acid. the super-case-ii transport (n> 1) model was in�uential if the release of mefenamic acid was done by reducing the polymer chains in the snedds (capryol-90, polysorbate-80 and peg-400) preparations and caplets (costa and lobo, 2001; lawrence and rees, 2012). dissolved mefenamic acid in either a non-polar solvent (capryol-90) after passing through a stagnant di�usion layer could immediately reduced the bond to the capryol-90 polymer followed by the breaking of the polysorbate-80 and peg-400 polymers to form the sif emulsion so that there became a reduction of the polymer chain, polysorbate-80, and peg-400 from micro to nano-size. the value of pure mefenamic acid capsule (0.1798) illus© 2018 the authors. page 170 of 172 mardiyanto et. al. science and technology indonesia, 3 (2018) 164-172 figure 5. physical properties of snedds mefenamic acid trates if the release of mefenamic acid only follow fick di�usion process (costa and lobo, 2001). this was because the pure capsule preparations were not added to the polymer so that the release only relied on the transfer of mefenamic acid through the homogeneous membrane which was strongly in�uenced by the sink conditions (martin and bustamante, 1993). 3.11 diameter analysis, pdi, and potential zeta of snedds droplet measurement of diameter of droplets on psa aims to determine the size of nanoemulsion droplets when in the digestive tract �uid. average diameter of the established snedds droplets was 241.9 nm with good size uniformity (pdi (18%) <20%) (figure 5). snedds zeta potential in -16.5 mv indicates if nanoemulsion dispersion tends to have slow coagulated and �occulated (martin et al., 1995). this was because a potential zeta value of ± 25 mv has been able to form a stable nanoparticle through the mechanism of forming a protective layer around the droplet from the pull of bonding together the dispersing medium to avoid the uni�cation of snedds droplet. the negative droplet surface snedds droplets was due to the negative electron oxygen (o) atom in the mefenamic acid group, polysorbate-80, peg-400 created an electron cloud on the emulsion molecule. 4. conclusions the proportion of capryol-90, polysorbate-80, and peg-400forming nanoemulsion regions of snedds mefenamic acid were 20-40%, 20-40%, and 40-60%, respectively. the proportion of capryol-90, polysorbate-80, and peg-400 in optimal formula of snedds mefenamic acid was (20; 31.62; 48.38)%. an optimal formula snedds showed the drug contentof (105.210 ± 4.425)%, the commercial generic caplet (0.917 ± 0.094)%, and mefenamic acid powder capsule (10.446 ± 0.333)%. an optimal formula revealed that the snedds could signi�cantly increase mefenamic acid dissolution of ph 7.4 (ileum �uid). the physical properties of mefenamic acid snedds successfully formed an uniformity droplet size (pdi 0.18) with mean size 241.9 nm and the surface charge had a value of -16.5 mv respectively. 5. acknowledgement authors would like to express their gratitude towards sriwijaya university pnbp kompetitif research grant 2018 that made this research possible, as well as indonesia islamic university (uii) yogyakarta and ltsit lampung university for all the help provided to complete this research. references anton, n. and t. f. vandamme (2009). the universality of low-energy nano-emulsi�cation. international journal of pharmaceutics, 377(1-2); 142–147 armstrong, n. a. 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balakrishnan, r. baskaran, s.-k. yoon, h.-g. choi, c. s. yong, b. k. yoo, and k. han (2010). novel self-nanoemulsifying drug delivery system for enhanced solubility and dissolution of lutein. archives of pharmacal research, 33(3); 417–426 © 2018 the authors. page 172 of 172 introduction experimental section materials methods determination mefenamic acid solubility in capryol-90 ternary phase diagram construction self-emulsification and precipitation ternary phase diagram study ratio component snedds mefenamic acid snedds mefenamic acid preparation snedds characterization drug content emulsification time and precipitation formula optimization study response snedds mefenamic acid in vitro dissolution diameter, pdi, and zeta potensial snedds globules statistic analysis optimized formula in vitro dissolution study results and discussion determination of mefenamic acid solubility in capryol-90 selection of snedds mefenamic acid component determination nanoemulsion and ternary phase diagram of mefenamic acid snedds visual observation of snedds mefenamic acid drug content measurement emulsification time and precipitation observation observation of physical stability response of the snedds mefenamic acid optimum formula statistical analysis of drug content, and emulsification time of optimum formula snedds in vitro dissolution diameter analysis, pdi, and potential zeta of snedds droplet conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper effect of plasticizer and concentration on characteristics of bioplastic based on cellulose acetate from kapok (ceiba pentandra) fiber rahmatullah1*, rizka wulandari putri1, muhammad rendana1, untung waluyo1, tedi andrianto1 1chemical engineering department, faculty of engineering, university of sriwijaya, palembang 30862, indonesia *corresponding author: rahmatullah@ft.unsri.ac.id abstract synthetic plastics made from petroleum material have been widely used in all industrial sectors. they bring some environmental problems. semi-synthetic plastics or biodegradable plastics which are made from natural polymers such as cellulose can solve this problem. biodegradable plastics can fulfill the needs of society because they can be decomposed easily into the environment. previous research of bioplastic production with kapok fiber as raw material only used glycerol as a plasticizer without the analysis of the characteristics of the bioplastic. in this study, variations of the plasticizer with sorbitol were carried out as well as physical and chemical analysis on the characterization of bioplastic products. this research used laboratory experimental methods through several processes: kapok fiber isolation, cellulose acetate production, purification, and manufacture of bioplastics. the characteristics of bioplastics were analyzed using some parameters such as density, tensile strength, elongation, young’s modulus, water absorption, biodegradability, compound group analysis using fourier-transform infrared spectrometer (ftir), and bioplastic morphology analysis by using scanning electron microscopy (sem). this study aimed to determine the effect of plasticizer and concentration on the bioplastics characteristics that was divided into several different concentrations of glycerol and sorbitol plasticizers (20%, 30%, and 40%). the fabrication of composite bioplastics used the cellulose acetate from kapok fiber, starch, and types of plasticizer (glycerol, and sorbitol). the results of the study showed that the addition of different plasticizers, such as glycerol and sorbitol gave distinct effects on the bioplastics product characteristics. the optimum concentration of glycerol addition affected the bioplastic characteristics with the best results were 40% concentration generate density of 0.836 g/ml, tensile strength of 0.818 mpa, water absorption value of 22.23%, and degradation plastic mass about 39.7%. the addition of sorbitol also affected the bioplastic characteristics, where the best results were 40% concentration produced bioplastic density of 0.941 g/ml, percent elongation at 3.94%, young’s modulus of 0.726 mpa, and degradation mass of 32.05%. the morphology of bioplastic showed high homogeneity at concentrations of 40% glycerol and 30% sorbitol. keywords bioplastic, gliserol, kapok fiber, celulosae asetate, sorbitol received: 10 september 2021, accepted: 12 december 2021 https://doi.org/10.26554/sti.2022.7.1.73-83 1. introduction human activities depend on plastic materials in their entire life. they use plastics for packaging in shopping, household furniture, medical devices, and other daily needs. the plastics are thrown away at the garbage places and most of them are non-degradable materials which then cause environmental and human health problems. in 2006, the ministry of environment and forestry reported that indonesia country contributes around 9.85 billion pieces of plastic bags every year, which are released from over 90 thousand modern retail outlets. plastic wastes generally need from 20 to 500 years for the decomposition process (ratnawati, 2020). it causes the garbage piles in indonesia that leads to disruption of environmental sustainability. in addition, jambeck et al. (2015) explained that indonesia is one of the second-largest contributors to plastic waste in the world with 3.2 million tons of plastic waste. around 12.7 million tons of plastic wastes have been dumped into the ocean by 192 coastal countries including indonesia. these issues motivate many researchers to �nd out the solution to plastic waste problems through alternative plastics with environmentally friendly characteristic. bioplastic production is one of the solutions to reduce the problem of environmental pollution. these bioplastics can be developed by natural polymers like cellulose. cellulose is one of the natural resources that potentially developed as a https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.73-83&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.73-83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 biopolymer due to its abundant presence, renewable sources, and easily decomposed. several plants are based on cellulosic sources for making bioplastics such as corn cobs, banana peels, sweet potato peels, and other plants. one of the natural �bers that are potentially used as bioplastics raw material is kapok (ceiba pentandra) �ber. kapok grows easily in indonesia, especially in tropical areas, such as on java island (mardiyati et al., 2018). indonesia is one of the largest cotton-producing countries in the world, accounting for 58,693 tons or 62.69% of the world’s total production. the production of cottonwood plantations in east java in 2015 achieved at 170 tons from manufactory farms, 1544 tons from the large private farms, and 25,288 tons for all regions in east java (of east java province, 2018). in previous studies, haryono et al. (2019) converted kapok (c.pentandra) seeds oil into biodiesel, while leaf extract of kapok (c.pentandra) was used to treat internal heat (febrila, 2019). kapok (c.pentandra) could also be used as activated charcoal for adsorbent (wahyuni et al., 2017), a mixture of rice husk briquettes (lestari, 2015), microcrystalline cellulose (mardiyati et al., 2018), composite reinforcement (purnawati et al., 2018), raw material for furfural production (andaka, 2016), and paper fabrication (kathomdani, 2018). several studies observed the use of cellulose as bioplastics raw material. andahera et al. (2019) analyzed the e�ect of adding the type and concentration of plasticizers on the quality of cellulose-based bioplastics from oil palm empty fruit bunches. pratiwi et al. (2016) produced cellulose from rice straw waste (oryza sativa) as the raw material of bioplastics. tamiogy et al. (2019) analyzed the cellulose production from betel nut peel waste as �ller of bioplastics with glycerol variations. rahmatullah et al. (2020) produced cellulose acetatebased bioplastics from kapok �ber by varied reaction time and glycerol concentration to determine the cellulose acetate yield and also bioplastics characteristics. however, studies that have analyzed the biodegradable plastic of cellulose acetate based on kapok �ber were still very limited. kapok �ber has the potential to be the raw material of cellulose acetate for bioplastic production due to the content of cellulose about 35%-64% (chaiarrekij et al., 2012). this work was conducted to study the e�ect of the type and concentration of plasticizers on the characteristics of bioplastic. in this study, the characteristics of bioplastic products were tested in physical and chemical analysis. in general, the added plasticizers, sorbitol, and glycerol gave di�erent e�ects on the bioplastic product, where the best results were obtained by adding sorbitol with a density value and degradation time that met the indonesian nasional standard. it can be concluded that cellulose from kapok �ber has the potential to be used as a material in bioplastic production. 2. experimental section 2.1 materials and methods this research is a modi�cation of andahera et al. (2019) and rahmatullah et al. (2020) in previous works. the process of cellulose-based bioplastics production from kapok �bers consisted of four stages: the cellulose isolation process, cellulose acetate synthesis, cellulose acetate puri�cation, and the bioplastic manufacturing process. the synthesis of bioplastics in this research used kapok �ber (original), starch (tapioca �our) (by pt melati putra jaya), aqua dest (by technical), alkaline water ph 8 (by local), glycerol (by merck), sorbitol (by technical), sodium hydroxide (naoh) (by merck), glacial acetic acid (ch3cooh (by merck), acetic anhydride ((ch3co)2o) (by merck), sulfuric acid (h2so4) (by merck). the characterization of bioplastics using ftir analysis using nicolet is10 ft-ir spectrometer, the sem analysis using sem edx tescan vega3. 2.1.1 kapok fiber cellulose insulation temperature of 100oc until constant weight. the dried kapok �ber was deligni�ed with 12% sodium hydroxide (naoh) solution (3.4 m) for 3 hours at a temperature of 75oc. the deligni�ed kapok �ber is �ltered and washed with distilled water until the acidity was neutral then bleached with 3.5% sodium hypochlorite (naocl) solution and mixed with aqua dest (1:1) at 75oc for 10 minutes. the bleached kapok �ber was washed thoroughly with distilled water until the acidity was neutral. neutralized kapok �ber was dried in an oven at 100oc until a constant weight. 2.1.2 synthesis of cellulose acetate kapok fiber the process of synthesizing cellulose acetate from kapok �ber was carried out in several stages. total 10 grams of kapok �ber cellulose was put into a three-neck �ask, then added 50 ml of glacial acetic acid (ch3cooh), and 0.5 ml of sulfuric acid. afterward, it was stirred evenly for 3 minutes, covered the �ask with aluminum foil, and left for 1 hour. after 1 hour, 50 ml of anhydrous acetic acid ((ch3co)2o) was added and followed by the addition of 20 ml of glacial acetic acid. then it was heated for 30 minutes at a temperature of 50oc. the mixture was cooled down at room temperature. added 50 ml of 70% glacial acetic acid (7.1 m) and 0.14 ml (3 drops) of sulfuric acid then reacted for 3 hours at 50oc. after the reaction was complete, the mixture was allowed to cool down until the temperature was lowered and then proceed with the puri�cation process. 2.1.3 puri�cation of cellulose acetate the synthesized cellulose acetate solution was put into a 1000 ml beaker, slowly added 25 ml of distilled water while kept stirring. total 500 ml of distilled water was added and stirred until homogenous state. the cellulose acetate solution was left until it became a solid phase mixed with a solvent. the cellulose acetate solution was �ltered using a buchner vacuum funnel with distilled water in addition to obtaining cellulose acetate solids. then, the cellulose acetate solid was washed and �ltered using a buchner vacuum funnel repeatedly until neutral. neutralized cellulose acetate was dried in an oven at a temperature of 100oc to a constant weight and pulverized. © 2022 the authors. page 74 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 2.1.4 bioplastic manufacturing total 1.5 grams of starch was dissolved in 9 ml of distilled water and heated for 15 minutes at 70oc while stirring continuously until gelatin was formed. then 1 gram of cellulose acetate was added and plasticizer, glycerol, and sorbitol were added in di�erent concentrations such as 20%, 30%, and 40%, respectively. the solution was stirred and heated at 50oc for 15 minutes until it appeared thick and clear. the produced bioplastic solution was molded in a petri dish lined with aluminum foil and left at room temperature to dry and form a bioplastic sheet. 2.2 bioplastic characteristic analysis 2.2.1 analysis of bioplastic functional groups the kapok �ber cellulose was analyzed by ftir (fourier transform infrared) machine. the sample was placed into the set holder, then searched for the appropriate spectrum. the result would be obtained a di�ractogram of the relationship between wavenumber and transmittance. the ftir spectra were recorded using a spectrophotometer at room temperature. 2.2.2 bioplastic film surface test the bioplastic �lm test observed the surface of the bioplastic �lm by using the sem (scanning electron microscopy) machine. the sem analysis was operated by following a procedure as the specimen was �xed in size about 12.5 mm then inserted into the chamber. the pumping procedure was started by clicking on the pump button in the vacuum panel then selecting the appropriate detector (se or bse). the accelerating voltage was set in (5 kv, 10 kv, 20 kv, 30 kv) using the combo box in the electron beam panel. by clicking on the hv button in the electron beam panel turns the high voltage on, it was started the heating of the tungsten �lament it was continued by pressing right-click in the sem scanning window to open the menu and selected the minimum magni�cation function. the resolution mode (wide �eld and resolution) was chosen and selected beam intensity (bi 10 recommended). 2.2.3 bioplastic density test the density test was conducted based on the procedure carried out by darni et al. (2017). a total 10 ml measuring cup was �lled with 5 ml of water and the bioplastic sample was put into the measuring cup for 15 minutes. then the new volume of water (v) was recorded and the actual volume of bioplastic was calculated by dividing the �nal volume of water by the initial volume of water. the density (d) of bioplastic was obtained with the equation 1 below: d = m v (1) where d was density (gram/ml), m was mass (gram) and v was volume (ml) 2.2.4 bioplastic tensile strength test the process of testing the tensile strength of cellulose acetatebased bioplastics from the kapok �bers was carried out using the universal testing machine. samples were cut to a size of 2 cm x12 cm. the sample was attached to a tensile tester with 1 �xed handle and 1 movable handle. furthermore, the thickness and initial length of the sample were recorded until the broken sample. the maximum force that splitted sample was �gured on the display device. the cross-sectional area is obtained by multiplying the length with the initial thickness of the sample. the tensile strength was calculated using the formula: f = f a (2) where f was tensile strength (mpa), f was force acting (n), a was a cross-sectional area (mm2) 2.2.5 percent elongation of bioplastic the elongation analysis of cellulose acetate-based bioplastic from kapok �ber produced was carried out by using the universal testing machine. based on the procedure from rifaldi et al. (2017), the percent elongation of bioplastics produced could be calculated by equation 3: elongation(%) = l1 −lo lo x100% (3) where l1 was the �nal length of the test object, lo was the initial length of the test object. 2.2.6 bioplastic young’s modulus test the young’s modulus value was obtained from the tensile strength and the percent elongation values that were generated by equation 4 (rifaldi et al., 2017): e = f y/100 (4) where e was modulus young (kpa), f was tensile strength (kpa) and y was elongation percentage (%) 2.2.7 water resistance test the initial bioplastic sample was weighed and the put into a container containing aquadest. the sample was taken out from the container every 10 seconds and weighed repeatly until obtained a constant �nal sample weight. the water absorbed on the bioplastic sample could be calculated by the following equation 5 (tamiogy et al., 2019). water(%) = w−wo wo x100% (5) where wo was the initial sample weight (g) and w was �nal sample weight (g) © 2022 the authors. page 75 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 figure 1. ftir spectrum of kapok fiber cellulose 2.2.8 bioplastic degradation test the degradation process of cellulose acetate from kapok �ber used the loose soil as decomposer media with an acidity degree around ph 6-7. the degradation test was carried out with two variations. the �rst was conducted by stockpiling in soil for 4 days. the second, it placed bioplastics on the free air as long as they were completely degraded. the bioplastic samples were weighed before the degradation test and reweighed every day until up to 4 days. degradation value was obtained from the percentage of mass degradation of bioplastic which was calculated based on equation 6 below: biodegradation(%) = a1 −a2 a1 x100% (6) where a1 was mass before testing (gram), a2 was mass after testing (gram). 3. results and discussion characteristic results of kapok fiber cellulose the kapok �ber raw material that was processed through deligni�cation and bleaching processes obtained a yield of about 47.5% bleached cellulose. the kapok �ber cellulose was analyzed by using ftir to identify the functional groups. the results of the ftir were shown in figure 1. the results of functional group analysis showed the absorption peak of the o-h group at a wavenumber of 3332.85 cm−1. this result indicated that the bleached kapok �ber contained cellulose. this was supported by rohmawati et al. (2018) which found after the isolation process in the 3349.78 cm−1 area, the cellulose content increased clearly. the isolated kapok �ber cellulose was indicated by the presence of certain cellulose groups, besides, the hydroxyl group, such as the methylene group of the c-h functional group at the absorption wave of 2892.50 cm−1 (pavia et al., 2001). the kapok �ber cellulose result still contained lignin which was indicated by the –oh group at the wave number 1630.61 cm−1. this result was supported by kumar et al. (2014) which found that the indication of lignin in cellulose product was shown by the presence of -oh groups at wavenumbers 1600-1700 cm−1. in addition, c=c groups were observed at wave absorption 2031.89 cm−1 to 2159.24 cm−1. 3.1 characteristics results of kapok fiber cellulose acetate cellulose acetate was produced by synthesizing kapok �ber cellulose with glacial acetic acid and anhydrous acetic acid with figure 2. cellulose acetate ftir spectrum of kapok fiber a sulfuric acid catalyst. the cellulose acetate in the form of a white solid was separated from water into a �ne powder of cellulose acetate. the yield of cellulose acetate obtained 114.6 g. cellulose acetate powder was identi�ed to determine the characteristics of functional groups using the ftir. cellulose acetate ftir test results could be seen in figure 2. the results of the ftir functional group analysis showed the presence of a c=o carbonyl group at a wavenumber of 1737.05 cm−1 and a c-o ester group from an acetyl group at a wavenumber of 1160.73 and 1217.92 cm−1 (figure 2. this phenomenon indicated the formation of cellulose acetate compounds with a sharp peak at wave number 1737.05 cm−1 and the decrease in the intensity of the oh group could be caused by the substitution of the acetyl group. nurhayati and kusumawati (2014) explained the cellulose acetate compound was formed with a sharp peak at a wavenumber of 1755 cm−1 and the oh intensity decreased due to the substitution of the acetyl group. the hydroxyl group in cellulose was sharper than the hydroxyl group in cellulose acetate, which was represented at wave 3435.85 cm−1. the ftir spectrum of cellulose acetate showed the acetylation process did not deteriorate the main structure of cellulose, indicating the presence of a speci�c cellulose c-h group at 2946.75 cm−1, -ogroup 1367.38 cm−1. this result was similar to a study by rohmawati et al. (2018) that found the main structure of cellulose did not decay the acetylation process due to the presence of cellulose groups. 3.2 bioplastic yield bioplastics produced with cellulose acetate base from kapok �bers by the addition of starch as an adhesive additive (1:1.5). bioplastic molding was carried out by glycerol and sorbitol addition as plasticizers with concentrations of 20%, 30%, and 40% respectively. the mass yield from the manufacture of this bioplastic was presented in table 1. 3.3 the e�ect of type and concentration of plasticizer on bioplastic functional groups the bioplastic characteristic test using ftir aimed to identify the functional groups content of bioplastics based on the e�ect of the type and concentration of plasticizers. figure 3 showed the spectrum of cellulose acetate-based bioplastic from kapok �ber with di�erent characteristics according to the concentration of glycerol indicated the presence of o-h groups. the wavenumber of 20% glycerol concentration © 2022 the authors. page 76 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 table 1. bioplastics yield plasticizer concentration bioplastic mass (gram) glycerol 20% 2.77 glycerol 30% 2.9 glycerol 40% 3.15 sorbitol 20% 2.71 sorbitol 30% 2.96 sorbitol 40% 2.78 figure 3. ftir result of bioplastic with added plasticizer: a) 20% glycerol; b) 30% glycerol; and c) 40% glycerol bioplastic was 3286.01 cm−1. bioplastic with 30% glycerol concentration was the sharpest wavenumber with an absorption area of 3284.92 cm−1. the highest wavenumber in bioplastics with the addition of 40% glycerol concentration was 3313.80 cm−1. this hydroxyl group indicated the presence of polymer compounds (lopes et al., 2018). the di�erent concentrations of glycerol plasticizer lead to the di�erent transmittance spectrum due to the addition of glycerol which resulted from hydrogen bonds formation (jannah, 2017). the wavenumber peaks at each concentration of glycerol 20%, 30%, and 40% were 2930.13; 2928.49; and 2937 cm−1, respectively. these results indicated the presence of c-h groups of cellulose acetate. based on the result of pavia et al. (2001), the c-h functional group was a cellulose acetate framework that appeared at wavenumber of 2800-3000 cm−1. the wavenumber of each glycerol concentration of 20%, 30%, and figure 4. ftir result of bioplastic with added plasticizer: a) 20% sorbitol; b) 30% sorbitol; and c) 40% sorbitol 40% were 1646.65, 1640.77, and 1640.07 cm−1, respectively, which indicated the presence of c-c groups of starch. the typical spectrum of starch appeared at a wavenumber of 1649 cm−1 which indicated the presence of c-c bonds (salinas-jasso et al., 2021). ftir analysis was conducted to identify the functional groups and to compare the characteristics di�erences by using a sorbitol plasticizer. figure 4 showed the ftir test results for bioplastics with the addition of the plasticizer sorbitol. figure 4 showed the wave number peaks of cellulose acetatebased bioplastics from kapok �ber. the peak wavenumbers were 3284.44 cm−1, 3285.08 cm−1, 3285.91 cm−1 indicated the presence of hydroxyl (o-h) groups and the presence of hydrocarbons (c=h) at wavenumbers 2927.08 cm−1, 2927.47 cm−1, and 2929.78 cm−1, indicating the compound of cellulose acetate. the hydroxyl group also exhibited the presence of sorbitol compounds. this was related to the result of kinney et al. (2012) which found that sorbitol had an absorption peak at a wavenumber of 3373 cm−1. the wavenumber at 1640 cm−1 indicated the presence of c-c groups of starch in bioplastics. ftir analysis results in table 2 represented that the synthesized bioplastics had similar wavelength values to their constituent raw materials. the addition of glycerol and sorbitol to cellulose acetate from kapok �ber did not denote the formation of new functional groups, however, the physical functional © 2022 the authors. page 77 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 table 2. results of ftir analysis on the main groups of bioplastic samples and the comparison on their constituent components component wavenumber (cm−1) -oh stretch c-h strecth c-h bending c-o acetyl c-o stretch cellulose acetate* 3200-3600 2850-3000 1350-1480 1210-1320 1000-1300 starch** 3388 2929 gliserol** 3286-3379.29 2880-2935 1200-1300 1000-1100 sorbitol** 3257 2937 g40 3313.8 2937 1367.27 1229.29 1021.62 g30 3284.92 2928.49 1366.66 1234.53 1017.34 g20 3286.01 2930.13 1366.52 1234.42 1014.4 s40 3285.91 2929.78 1366.34 1233.97 1000.6 s30 3285.08 2927.47 1366.15 1236.16 s20 3284.44 2927.06 1366.03 1234.71 table 3. comparison of characterization of the bioplastic parameter indonesian national bioplastic from kapok �ber with variation of type and concentration plasticizer standard g20% g30% g40% s20% s30% s40% density (g/ml) 0.941-0.955 0.602 0.753 0.836 0.753 0.836 0,941 tensile strength (mpa) 24.7-302 0.164 0.014 0.818 0.327 0.204 0.286 elongation (%) 21-220 2.63 1.29 2.59 2.63 1.35 3.94 modulus young (mpa) 117-137 0.622 0.111 0.316 0.124 0.151 0.726 water absorption (%) 21.5 37.72 27.61 22.23 37.27 50.39 51.17 mass of degradation >60% 26.11 28.46 39.7 23.78 23.36 32.05 (7 days) (4 days) (4 days) (4 days) (4 days) (4 days) (4 days) biodegradation time 60 days 27 days 27 days 27 days 27 days 27 days 27 days group interactions were shifted in wavenumbers in the oh, ch, and co groups through the spectrum readings. the oh and co stretch groups indicated the hydrophilic groups due to water molecules could cause microorganisms in the environment to enter the bioplastic matrix and lead the bioplastic damage (nahir, 2017). the presence of the c-o functional group indicated that the plastic �lm could be degraded well in the soil and was easy to decompose (siregar, 2009). these phenomenons signi�ed that the process of bioplastic production was a mixing process without any reaction of its constituent materials, this phenomenon caused the bioplastic products to have properties that seem like their constituent components and were easy to decompose. 3.4 the e�ect of type and concentration of plasticizer on bioplastic surface morphology sem analysis on cellulose acetate-based bioplastic from kapok �ber aimed to determine the surface characteristics of the bioplastic �lm and morphological structure of bioplastic. bioplastic surface analysis was carried out by the sem analysis with 2,000× magni�cation. figure 5 represented sem results bioplastics with the addition of glycerol in di�erent concentrations. figure 5 showed that the bioplastic with the addition of 20% glycerol obtained an irregular and rift surface. there was open pores appearance with cracks and holes. the cracks figure 5. sem test results of bioplastic plasticizer glycerol concentration a) 20%, b) 30%, and c) 40% might be caused by the cellulose acetate that was incompletely dissolved with starch in the addition of 20% glycerol solvent. the presence of cavities and cracks in bioplastics indicated the cellulose acetate with glycerol as a plasticizer did not bind to each other due to the small glycerol concentration (tamiogy et al., 2019). the surface of bioplastics with the addition of 30% glycerol seem smoother than the addition of 20% glycerol, but it still had visible lumps of particles on the surface. however, there were no visible pores or cracks on the surface of the bioplastic 30% glycerol. it might be caused by the mixing process of starch, cellulose acetate, and glycerol solvent have been well homogenized. this was supported by the result of © 2022 the authors. page 78 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 figure 6. sem test results of bioplastic plasticizer sorbitol concentrations a) 20%, b) 30%, and c) 40% figure 7. results of bioplastic density on the type and plasticizer concentration variation maneking et al. (2020) that stated the combination of starch, glycerol, water, and acetic acid combination showed the smooth surface morphology without cracks and pores were formed. the addition of 40% glycerol bioplastic surface was slightly smoother than the addition of 20% and 30% glycerol. however, there were still found few visible pores, cracks, and bumps on the surface of the bioplastic. the results of the sem analysis of bioplastics with sorbitol plasticizer were shown in figure 6. figure 6 showed the results of sem analysis from the bioplastic with the addition of 20% sorbitol. the result found the surface of the bioplastic was quite smooth and raggy. it was also had some pores and cracks on the surface of the bioplastic sample. the bioplastic surface with 30% sorbitol had some pores and cracks but less than 20% sorbitol. on the other hand, the addition of 40% sorbitol on bioplastic had a slightly smoother surface with fewer pores than 20% and 30% sorbitol. the tight surface of the bioplastic lead to higher resistance of water absorption (setiawan et al., 2015). 3.5 the e�ect of type and concentration of plasticizer on bioplastic density density analysis aimed to determine the density of the atoms compounds in bioplastic material that interacted with each other. the interaction a�ected the mechanical properties of the material. the denser the bioplastic, the higher its mechanical properties. the relationship between the type and concentration of plasticizer on the bioplastic density was shown in figure 7. the results showed that the increased density was in�ufigure 8. results of bioplastic tensile strength based on the type and plasticizer concentration variation enced by the high concentration of plasticizer added according to each type of plasticizer glycerol and sorbitol. the lowest density was obtained from the glycerol plasticizer with a concentration of 20% (0.602 g/ml). while the highest density value was found in 40% glycerol (0.836 g/ml). similarly, the concentration of 40% sorbitol lead to the highest density value. the type and concentration of plasticizers had a signi�cant e�ect on the density value of the bioplastic products. this was supported by darni et al. (2017) who stated that the higher the density value of a material would lead to the tighter the molecular structure. the bioplastic product had a tight structure, thus it would be more di�cult for water molecules to enter the bioplastic pores. the density value of cellulose acetate-based bioplastic from kapok �ber with a 40% concentration of sorbitol plasticizer was 0.941 g/ml, which was closest to the density of ldpe plastic. the density value of ldpe ranged from 0.941 to 0.955 g/ml (darni et al., 2017). most of the bioplastic density values produced were still low and far from to the density values of ldpe. this was due to the mixing of cellulose acetate, starch, and plasticizers in the manufacture of bioplastics were not homogeneous. based on the result of tamiogy et al. (2019), the �uctuating density value of the bioplastic �lm occurred due to the inhomogeneous mixing between starch and cellulose. 3.6 the e�ect of type and concentration of plasticizer on tensile strength of bioplastics tensile strength analysis was carried out to determine the effect of the type and concentration of plasticizer on the tensile strength of cellulose acetate-based bioplastic from kapok �ber that was shown in figure 8. tensile strength analysis aimed to determine the ability of bioplastics to restrain the weight of the given load until it broke (andahera et al., 2019). the tensile strength values of bioplastics product from each type and concentration of plasticizers variant ranged from 81.75 to 327 kpa. the highest bioplastic tensile strength value was obtained at a 20% concentration of sorbitol plasticizer, which was able to hold a load of 327 kpa. this was consistent with another study by azizaturrohmah (2019) where the maximum tensile strength was obtained at the concentration of 20% sorbitol. the bioplastics with 40% glycerol concentration had the © 2022 the authors. page 79 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 figure 9. the percent elongation of bioplastics on variation of type and plasticizer concentration lowest tensile strength value with the capability to hold a load of 81.75 kpa. the bioplastic tensile strength of the glycerol plasticizer decreased as the concentration was added. based on the result by intan and wan (2011), the higher the concentration of plasticizer leads to the decrease in interaction between bioplastic molecules. it involved the bonds between bioplastic molecules became weak which lead to lower the tensile strength value. the addition of sorbitol as a bioplastic plasticizer resulted in a higher tensile strength value than glycerol plasticizer. riza et al. (2013) also showed a similar result that sago starch bioplastic with sorbitol plasticizer had a higher tensile strength value than glycerol plasticizer. this phenomenon was because glycerol had a smaller molecular weight than sorbitol. glycerol was easier to enter into the polysaccharide bonding spaces, as the increase of number of spaces in bonds and the decrease of intermolecular bonds (ningsih, 2015). according to sitompul and zubaidah (2017), the molecular structure of sorbitol was di�cult to insert into polysaccharide bonds because the molecules of sorbitol were larger than glycerol thus it could stretch the existing bonds. besides, sorbitol had the ability to produce bioplastics with greater tensile strength than glycerol because of sorbitol crystallinity (unsa and paramastri, 2018). 3.7 the e�ect of plasticizer type and concentration on bioplastic elongation percentage the elongation percentages analysis of cellulose acetate-based bioplastic from kapok �ber aimed to determine the percentage of the bioplastic length changes before it was broken o�. figure 9 presented the e�ect of the type and concentration of plasticizer on the percent elongation value. the elongation percentage of the bioplastic products was quite di�erent for each type and concentration of plasticizer. the di�erences were due to the distinct compositions of the bioplastics product. the elongation value ranged from 1.29 to 3.94%. the addition of 20% plasticizer to glycerol and sorbitol showed the same result as the elongation value of about 2.63%. the elongation percentages value decreased at the concentration of 30% plasticizer. the highest percentage of elongation was obtained from the addition of 40% sorbitol about 3.94%. the addition of 30% glycerol obtained the smallest elongation figure 10. young modulus young of bioplastic base on type and plasticizer concentration percentage of about 1.29%. the elongation value of bioplastic with the addition of the plasticizer concentration of 40% increased signi�cantly. this increase occurred because the plasticizer would reduce the intermolecular bonds between amylose and amylopectin with starch or cellulose acetate thus it a�ected the hydrogen bonding of starch molecules with the plasticizer (sanyang et al., 2015). da rosa zavareze et al. (2012) revealed that the elongation percentage of polymeric materials depended on the mobility of the molecular chains of a polymer. 3.8 the e�ect of plasticizer type and concentration on young’s modulus of bioplastics young’s modulus test on cellulose acetate-based bioplastic from kapok �ber aimed to determine the elasticity value of the resulting bioplastic. young’s modulus value was calculated by comparing the tensile strength (tensile strength) to the elongation at a breakpoint (rifaldi et al., 2017). figure 10 showed the results of young’s modulus of bioplastic according to the type and concentration of plasticizers. based on figure 10, the highest value of young’s modulus was obtained in a 30% concentration of sorbitol plasticizer about 151.41 kpa. while the lowest value of young’s modulus was 31.5637 kpa in a 40% glycerol plasticizer. the decrease in the value of young’s modulus was caused by the amount of concentration of plasticizer. the increase of plasticizer concentration leads to the increase of bioplastic elasticity. in contrast, it caused a smaller of young’s modulus value. according to nahwi (2016), glycerol plasticizer was more e�ective because of its ability to reduce internal hydrogen bonds by increasing the empty space between molecules. also, it could be a�ected by the reduction of sti�ness and the increase of the bioplastics �exibility. the empty space would be �lled by a plasticizer that reduced the interaction tension between starch molecules. 3.9 the e�ect of type and concentration of plasticizer on bioplastic water resistance water-resistance test aimed to determine the ability of bioplastics to absorb water. the water absorption capacity of bioplastics was expected to be low to prevent bioplastics defects. figure 11 represented the bioplastic water adsorption percentage according to the type and concentration of the plasticizer. © 2022 the authors. page 80 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 figure 11. the water absorption results on the type and concentration of plasticizer variation figure 11 showed that the higher concentration of glycerol resulted in lower water absorption. this indicated that the higher concentration of glycerol added, the water would be more di�cult to be absorbed and the bioplastic was more resistant to the water. contrarily, the increase of sorbitol concentration would lead to the higher absorption of water. the water absorption value of bioplastic with the addition of sorbitol was signi�cantly above the average water absorption in glycerol bioplastics. the higher absorption capacity a�ected the lower water resistance product. the best water resistance characteristics were obtained in the bioplastics with the concentration of 40% glycerol about 22.23% of water absorbed and 37.37% of water absorption in 20% sorbitol. the results of this study were di�erent from previous studies. a study by tamiogy et al. (2019) found that the water absorption of bioplastic was �uctuating at each concentration of plasticizer. the type and concentration of plasticizers could a�ect the value of the water-resistance of bioplastic where the addition of plasticizers could increase the permeability of the bioplastic product. the low water absorption and the high glycerol concentration were in�uenced by the small glycerol molecule size thus it easily entered the intermolecular bonds. the distance between molecules was wider thus the cellulose acetate and starch could easily enter to �ll the distance between molecules. this phenomenon a�ected the water became di�cult to enter the molecule (azizaturrohmah, 2019). in contrast, the high absorption value occurred in the increase in sorbitol concentration due to the larger sorbitol molecule size. the distance between molecules became closer thus the cellulose acetate and starch was di�cult to �ll the bond distance. the water would be easily absorbed in a bond distance of bioplastics (maghfur, 2015). the bioplastic product was more resistant to water in the addition of glycerol as a plasticizer. it had a good absorption value compared with bioplastics with sorbitol plasticizer. 3.10 the e�ect of plasticizer type and concentration on bioplastic biodegradation the biodegradation analysis of cellulose acetate-based bioplastic from kapok �ber aimed to determine the decomposition time for bioplastics when it was disposed to the environment. figure 12. results of degraded bioplastic mass percentage based on the type and concentration of plasticizer the process of biodegradation analysis was carried out by burying with soil then observing the bioplastic mass degradation percentage from the �rst day to the fourth day. the results of the mass percent of the degraded bioplastics were presented in figure 12. the percentage yield of degraded bioplastic mass increased from the �rst day to the fourth day with a signi�cant increase in high concentrations of plasticizer. the addition of 40% glycerol concentration leads to the highest degradation mass percentage about 39.7%. while there was a �uctuating degradation mass percentage in the addition of sorbitol. the highest percentage of degradation 40% sorbitol was 32.36% of the mass degraded. the mass percent yield of degraded bioplastic was di�erent from a study by andahera et al. (2019) where the largest percentage of degraded mass was obtained with the addition of sorbitol with the smallest concentration around 10%. while the addition of 30% sorbitol had the smallest reduction value of the degraded mass. this di�erence was due to the homogeneity factor in the mixing of sorbitol with cellulose acetate and starch, where the mixing was not homogeneous, the bioplastic would be easily degraded by the soil. the bioplastics biodegradation by buried with soil aimed to determine the time depth for bioplastics completely decomposing in soil. this biodegradation process was checked periodically every day to determine the development physical appearance changes of bioplastics decomposed for seven days. bioplastic on the �rst day was the original form of bioplastic which was still intact and has not been degraded yet by the soil. on the 7th day, the bioplastic have changed its form to become duller and began to be degraded by the soil, and there were some cracks on the bioplastics. another study done by isnaini (2019) showed that in the �rst week, nipa fruticans’ bioplastics were in the form of clear sheets. in the 2nd week, the bioplastic changed color to a dull yellow and has decreased in mass. in the 3rd week there was a decrease in mass and black spots appeared, while at the 4th week there were more black spots on bioplastics. the degradation test with the addition of sorbitol reached the range of 22% 70% in 1 week. bioplastics with the addition of glycerol plasticizer were easier to decompose than bioplastics with sorbitol plasticizer due © 2022 the authors. page 81 of 83 rahmatullah et. al. science and technology indonesia, 7 (2022) 73-83 to the characteristics of glycerol which was more easily bound to water than sorbitol. it a�ected bioplastics to be more easily damaged when they were placed in the soil. moreover, the hydroxyl group (o-h) in glycerol would cause a hydrolysis reaction in bioplastics with water content in the soil that resulted in bioplastics damage (ardiansyah, 2011). meanwhile, bioplastics with sorbitol plasticizer had a longer degradation time due to the larger molecular weight of sorbitol that made stronger intermolecular bonds. the strong intermolecular bonds would be di�cult to damage or decompose the soil (sitompul and zubaidah, 2017). 3.11 comparison of bioplastic products characteristics with indonesian national standard (ins) bioplastics. the bioplastic product had characteristic parameters that should be considered based on the indonesian national standard (ins). table 2 showed the comparison of the characteristics of the bioplastics products with ins bioplastics. based on the results of bioplastics, it could be concluded that only two characteristics were close to the indonesian national standards, namely density and mass of degradation for the addition of 40% concentration of sorbitol with density value about 0.941 (g/ml) and degradation mass about 32.05%. 4. conclusions based on the results of the study, it concluded that the type and concentration of plasticizers namely sorbitol and glycerol gave di�erent e�ects on the characteristics of the bioplastics product. the best result of glycerol addition for the bioplastic characteristics was in 40% concentration for highest wavenumber of oh groups about 3313.80 cm−1, with the smoother and fewer pores, density about 0.836 g/ml, tensile strength about 0.818 mpa, water absorption value around 22.23%, and degradation plastic mass about 39.7%, and the 20% concentration for percent elongation at 2.63% and young’s modulus about 0.662 mpa. the addition of sorbitol also a�ected the bioplastic characteristics, where the best result was found in 40% concentration with the highest wavenumber of oh groups about 3285.91 cm−1, with the smoother and fewer pores, bioplastic density of about 0.94 g/ml, percent elongation at 3.94%, young’s modulus about 0.726 mpa, and degradation mass about 32.05%, and the 20% concentration for tensile strength value about 286.1 kpa and water absorption at 37.27. the best result where the density and mass of degradation were close to the standard which was found in the 40% sorbitol sample with density around 0.94 g/ml and degradation mass around 32.05%. 5. acknowledgement this research was funded by sriwijaya university. therefore, we appreciate for the help and support in this work. we also thank the reviewer colleagues who have given suggestions in this manuscript. references andahera, c., i. sholikhah, d. a. islamiati, and m. d. pus�tasari (2019). e�ect of addition of types and concentrations of plasticizers on the quality of cellulose-based bioplastics from oil palm empty fruit bunches. indonesian journal of pure and applied chemistry, 2(2); 46–54 andaka, g. 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83 introduction experimental section materials and methods kapok fiber cellulose insulation synthesis of cellulose acetate kapok fiber purification of cellulose acetate bioplastic manufacturing bioplastic characteristic analysis analysis of bioplastic functional groups bioplastic film surface test bioplastic density test bioplastic tensile strength test percent elongation of bioplastic bioplastic young's modulus test water resistance test bioplastic degradation test results and discussion characteristics results of kapok fiber cellulose acetate bioplastic yield the effect of type and concentration of plasticizer on bioplastic functional groups the effect of type and concentration of plasticizer on bioplastic surface morphology the effect of type and concentration of plasticizer on bioplastic density the effect of type and concentration of plasticizer on tensile strength of bioplastics the effect of plasticizer type and concentration on bioplastic elongation percentage the effect of plasticizer type and concentration on young's modulus of bioplastics the effect of type and concentration of plasticizer on bioplastic water resistance the effect of plasticizer type and concentration on bioplastic biodegradation comparison of bioplastic products characteristics with indonesian national standard (ins) bioplastics. conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper preparation and application of nickel electroplating on copper (ni/ec) electrode for glucose detection muh. supwatul hakim1, haryoko pangestu1, riyanto1* 1department of chemistry, faculty of mathematics and natural sciences, islamic university of indonesia, yogyakarta, 55584, indonesia *corresponding author: riyanto@uii.ac.id abstractan electrode of the nickel electroplating on copper (ni/ec) has been prepared for a simple and low cost glucose sensor in humanurine detection. the electrode was prepared by using pure copper (99.9%) with electroplating method in niso4 solution. theelectrochemical oxidation of ni/ec electrode was investigated bys using cyclic voltammetry method. material ni/ec identification ofmorphology used scanning electron magnetic (sem) and energy dispersive x-ray (edx). the electrochemical reaction of glucosewas analyzed by the cyclic voltammetry method in some electrolyte solutions. calibration curved was constructed and a linearresponse for glucose concentration at range 0-0.004 m with r2= 0.992, lod and loq was determined 4.85x10−4 m, 1.6x10−3respectively. the proposed electrode might open up a new possibility for the determination of glucose concentration in human urine.its advantages are simple to prepare, low cost analyzing, and excellent results. keywordsglucose, electroplating, human urine received: 19 october 2021, accepted: 16 march 2022 https://doi.org/10.26554/sti.2022.7.2.208-212 1. introduction diabetes is a condition in which blood glucose levels are higher than the normal range of 4.4-6.6 mm (amatatongchai et al., 2017). it is caused by insulin production in the body’s cell decrease. people with a high concentration of glucose are more prone to suer renal, retinal and neural complications (guo et al., 2015). their blood glucose concentration must be controlled several times. diabetes is one of the most serious problems for human society. data who shows indonesia has fourth ranks country with high diabetes mellitus cases and estimated will be increased in 2025 (hakim and riyanto, 2018). therefore, sensitive, selective and accurate detection is very important. somemethodsforthedetectionofglucose inproducts, food and urine sample have been interested. the application of enzyme-based to analysis glucose have been aected by temperature, ph, humidity and toxic chemicals. unlike sensors using an enzyme, the non-enzymatic glucose sensors have advantages such as high stability, rapid response, high selectivity and accurate measurement (xu et al., 2010). some of the electrodes have been developed for glucose analysis like glassy carbon (raziq et al., 2017), gold (xu et al., 2010), nickel sulde (kannan and rout, 2015), cu(wu et al., 2010), pb (cui et al., 2007) and other hybrid materials. a nickel/carboncompositewasusedasanelectrodeforthenonenzymatic glucose sensor (marini et al., 2018). ni nanoparticle electrodes were investigated for the detection of glucose with a nonenzymatic sensor based on the formation of a high valent of ni in high ph conditions (yu et al., 2012). 2. materials and methods 2.1 materials and apparatus glucose, kno3, naoh, koh, niso4, nicl2, h3bo3, and other chemicals reagents were purchased from merck (darmstadt, germany). the electrochemical studies were conducted at room temperature and carried out using cyclic voltammetry pgstat 100 n/250 mv (metrohm autolab). the counter and reference electrodes were made of pt wire and ag/agcl (metrohm switzerland). 2.2 preparation of ni/ec electrode the ni/ec electrode was prepared by the electrodeposition method in nickel ion solution as described by riyanto and roda (2019). briey, the cu metals wire (aldrich chemical) was formulated by length 0.5 cm and wide of 0.1 cm. cu metals wire was immersed in a nickel ion solution with dc voltage. the nickel plating on copper was connected using conductive silver paint to silver cable. the electrode ready to use as a working electrode. the process of electrodeposition https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.208-212&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.208-212 hakim et. al. science and technology indonesia, 7 (2022) 208-212 nickle on copper shown in figure 1. figure 1. schematic of nickel electroplating on copper 2.3 characterisation and glucose detection the morphology of the electrodes was investigated using scanning electron magnetic (sem), while the element was determined by means of energy dispersive spectrometry (eds) to look surface of electrode. glucose detection was performed by the cyclic voltammetry method. the cell electrochemical reaction was shown in figure 2. pt wire used as the counter electrode, ni/ec as the working electrode and ag/agcl as the reference electrode. koh, naoh and kno3 solution were determined for good electrolyte in electrochemical detection of glucose. figure 2. electrochemical cell 3. results and discussion 3.1 characterization of ni/ec the preparation of ni/ec electrode was illustrated as figure 1. ni was deposited on copper by taking electrochemical deposition method. the morphology of these electrode was examined using sem. ni/ec electrode shows smooth morphology (figure 3). figure 3a the morphologyof the ni/ec surface can be seen that there is a layer on the surface of cu metal which is doped with ni metal with a magnication of 5 times (figure 3a) and 5000 times (figure 3b) used sem. figure 3c, can be seen that the results of ni deposited onto cu metal material have been successful with a percent weight (%wa) of ni deposited onto cu of 91.46% of the edx results. more than ni metal has been successfully doped in cu. this metal pile binds cu in a coordinated interaction between ni and cu. figure 3. morphology scanning electron magnetic (sem) of material ni/ec surface with magnication 5 times (a), 5000 times (b) and result of energy dispersive x-ray (edx) from sem data surface electrode ni/ec (c) 3.2 determination of electrolyte and electrocatalytic oxidation of glucose the cvs in koh 0.1 m solution in the absence and presence of glucose are shown in figure 4a. its show the cvs in the absence of glucose from +0.0 to +2.0, there is no increase peak current of cv in the presence of glucose. figure 4b shows a cyclic voltammogram from potential +1,0 v to -1,0 v in kno3 0.1 m solution in the absence and presence of glucose. the cathodic and anodic peak was not conrmed in kno3 solution. the cvs of the ni/ec electrode in alkaline solution in the presence and absence of glucose are presented in (figure 4c). the cyclic voltammogram of ni/ec in 0.1 m naoh solution showed nonsymmetrical wave, between anodic and cathodic peak with potential at about +5.78 v and +3.44 v versus reference electrode. the electrochemical reaction of ni(iii)/(ii) in the alkaline solution may be described as following (zhao et al., 2007). ni + 2oh− − e− −→ nio(oh). or ni(oh)2 + oh− − e− −→ nio(oh) + h2o when ni(0) is oxidized to ni(ii) at a potential smaller than -600 mv, nio and ni(oh)2 are formed (luo et al., 1996). ni + 2oh− − e− −→ nio + h2o ni + 2oh− − e− −→ ni(oh)2 based on previous research, carbohydrates can be oxidized at strong basic (das et al., 2006). as shown in figure 4c, the nickel ion on the electrode’s surface works as a catalyst for the oxidation of glucose. the potential reduction and oxidation peak about 358 mv, 654 mv, respectively. glucose is quickly © 2022 the authors. page 209 of 212 hakim et. al. science and technology indonesia, 7 (2022) 208-212 figure 4. cvs of ni/ec electrode in absense (a) and presence (b) of glucose 0.001 m in (a) koh 0.1 m solution, (b) kno3 0.1 m solution and (c) naoh 0.1 m solution. scan rate 100 mvs−1 oxidized to gluconolactone and increasing anodic peak when the addition of glucose (figure 4c). figure 5. cvs of ni/ec electrodes in naoh 0.1 m at dierent glucose concentrations scan rate of 100 mvs−1 the eect of dierent glucose concentrations on ni/ec was investigated. the results (figure 5) showed that the peak currents were gradually increased by increasing glucose concentrations. as can be seen, glucose may be oxidized in an alkaline solution, and the nickel ion functions as a catalyst in this reaction. the cyclic voltammetry method was used to evaluate the electrocatalytic oxidation of ni/ec electrodes in naoh 0.1 m solution. figure 5 indicates that when glucose was added to the naoh solution, the anodic peak increased and the potential switched to a more positive state, whereas the cathodic peak declined without anyfurtherpotential changes. it indicates that the oxidation of glucose was an irreversible electrochemical process. mechanisms reaction described by (cai et al., 2017; yu et al., 2012) oxidation of glucose in the surface of the electrode (figure 6): figure 6. reaction possible of glucose in surface ni/ec electrode ni(oh)2 + oh− −→ nio(oh) + e− nio(oh) + glucose −→ ni(oh)2 + glucolactone the calibration curves of glucose were obtained by cyclic voltammetry results (figure 7). it shows the calibration curve of glucose with a current peak for the ni/ec electrode. the cv determined for glucose with the dierent concentrations that were linear at range 0-0.004 m. the calibration curve was created with a ni/ec electrode with the correlation (r2) is 0.992 and a linear regression is y= 0.133x+0.000276. the linear regression equation can be used to determine glucose concentration in a sample of human urine. figure 7. the corresponding calibration curve of ni/ec electrode figure 8 shows the cvs of ni/ec electrode with various scan rates in 0.1 m naoh containing 0.001 m of glucose. the results showthat the cathodic and anodic peakcurrent increases linearly with the increasing scan rate in the range of 10-100 mv/s, the r2 of 0.995 and 0.990 for the anodic and cathodic peak. it indicates the electrochemical reaction is controlled on the surface of the electrode. a comparison of the performance of ni/ec with other glucose sensors shown in table 1. it can be noted that all of the them have dierences limit of detection with other modied material. as-prepared ni/ec electrode oered lower detection limit than gold glyconanoparticle. gc/mwcnt/niooh and se-mcm-41 mesoporous have detection limit 4.3x10−3, © 2022 the authors. page 210 of 212 hakim et. al. science and technology indonesia, 7 (2022) 208-212 table 1. comparison of determination glucose with some published work electrode/material method lod (m) reference gold glyconanoparticle colorimetric bioassay 2.01x10−3 (lim et al., 2013) (gc/mwcnt/niooh) cyclic voltammetry 4.3x10−4 (de sá et al., 2014) se-mcm-41 mesoporous composite amperometric 1x10−4 (yusan et al., 2018) ni/ec cyclic voltammetry 4.85x10−4 this work figure 8. cyclic voltammogram of various scan rate (10-100 mvs−1) in 0.001 m glucose table 2. validation method of purpose electrode no. parameters value 1 linierity 0.992 2 lod (m) 4.85x10−4 m 3 loq (m) 1.6x10−3 m 4 precision (%) 3.85 5 recovery (%) 90.2-105.26 1x10−4 respectively. however, theirmethodswerecomplicated and the material used in the fabrication were more expensive. the advantages of the proposed electrode are simple and lowcost preparation. the proposed electrode is suitable for the determination of glucose concentration in the urine sample. table 2 shows the parameters of the validation method in glucose analysis with cyclic voltammetry. this method was very useful and promised for glucose determination in human urine sample. table 3. application for real sample sample glucose added (m) glucose founded (m) recovery (%) 0.0012 a 0.002 0.0031 93.99 0.003 0.0039 90.22 0.0014 b 0.002 0.0035 105.26 0.003 0.0043 95.24 3.3 application for real samples the proposed electrode was used to detect glucose in urine samples from humans. the current peak was measured after 5 mlof human urine samples were added to 5 mlnaoh 0.1 m solution. the recovery of ni/ec electrode was analyzed using spiking method in pure glucose solution containing human urine sample. the results (table 3) show recoveries of the sensorabout 90.2-105.26%, which indicates the electrode great potential to determine glucose concentration in human urine samples. 4. conclusions in summary, ni/ec electrode material has been prepared to investigated for glucose detection. the material ni has been doped by electroplating in cu metal. ni/ec has been successfully and investigation surface by sem-edx. sem data on to surface ni/ec electrode formed layer and edx data showed 91.46% (weight atom) doped in cu metal surface. all detection for glucose with electrochemical reaction. 0.1 m naoh it is good electrolyte for reaction glucose in surface electrode ni/ec to electrochemical reaction. calibration curved was constructed and a linear response for glucose concentration at range 0-0.004 m with r2= 0.992, lod and loq was determined 4.85x10−4 m, 1.6x10−3 respectively. 5. acknowledgment the authors thank to department of chemistry and integrated laboratory islamic university of indonesia for providing facilities during the research and activities. references amatatongchai, m., w. sroysee, s. chairam, and d. nacapricha (2017). amperometric flow injection analysis of glucose using immobilized glucose oxidase on nano-composite carbon nanotubes-platinum nanoparticles carbon paste electrode. talanta, 166; 420–427 cai, h., b. sun, h. chen, x. li, h. suo, and c. zhao (2017). enhanced electrochemical glucose-sensing properties of nio nanospheres modied with indium. journalofmaterials science, 52(19); 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nanoparticles decorated titania nanotube arrays as ecient nonenzymatic glucose sensor. electrochimica acta, 76; 512–517 yusan, s., m. m. rahman, n. mohamad, t. m. arrif, a. z. a. latif, m. a. ma, and w. s. b. wan nik (2018). development of an amperometric glucose biosensor based on the immobilization of glucose oxidase on the se-mcm41 mesoporous composite. journal of analytical methods in chemistry, 2018; 1–8 zhao, c., c. shao, m. li, and k. jiao (2007). flow-injection analysis of glucose without enzyme based on electrocatalytic oxidation of glucose at a nickel electrode. talanta, 71(4); 1769–1773 © 2022 the authors. page 212 of 212 introduction materials and methods materials and apparatus preparation of ni/ec electrode characterisation and glucose detection results and discussion characterization of ni/ec determination of electrolyte and electrocatalytic oxidation of glucose application for real samples conclusions acknowledgment science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2016) 1-7 arti cle http://sciencetechindonesia.com @2016 published under the terms of the cc by nc sa 4.0 license 1 preparation and characterization of calcium oxide from crab shells (portunus pelagicus) and its application in biodiesel synthesis of waste cooking oil, palm and coconut oil m inaria1,*, risfidian m ohadi1 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding authror e-mail : minariaar@gmail.com abstract preparation of calcium oxide from portunus pelagicus through thermal decomposition for 3 hours at various temperature 700°c, 800°c,900°c,1000°c, and 1100°c. the calcium oxidefrom decomposition was carried out and characterized by x-ray diffractometer (xrd), ft-ir spectrophotometer and sem-edx analyses. the result of xrd show decompositio n portunus pelagicus at 1000°c have diffraction pattern agree with the cao diffraction standard with 2θ value 32.4º, 37.5º, 64.3º, and 67,5º. the ft-ir spectrum show vibration of cao at wavenumber 354.9 cm -1. sem-edx data indicated the surface morphology calcium oxide of portunus pelagicus more homogen than portunus pelagicus before decomposition. the decomposition of cao at 1000°c was applied in the syntesis of biodiesel from waste cooking oil, palm oil, and coconut oil. the biodiesel products have dens ity 0.8621, 0.8725, and 0.8688 g/cm 3. viscosity are 5.27, 3.71, and 2.45 mm 2/s(cst). acid values respectively are 0.3069, 0.2423 and 0.2100 mg/koh and iodine numbers 39.48, 36.12 and 9.24 g i2/100g. all characteristi c of biodiesel from waste cooking oil, palm oil, and coconut oil are agree with sni standard. the best biodiesel product derived from coconut oil is agree to the parameter value of biodiesel st andard. keywords: biodiesel. portunus pelagicus. calcium oxide. catalyst. intro duction biodiesel is an alternative of diesel fuel, made from biodegradable sources such as vegetable oils and anim al fats that are biodegradable, non-toxic, have low filtration profiles and environmentally friendly (ma et al., 1999). biodiesel is an alternative fuel used as a renewable energy source and is also a sustainable fuel (boey et al. 2009). sources of raw materials to synthesize biodiesel include, for example, vegetable oils and anim al oils, including cooking oil. one of the ways to create biodiesel is through using triglyceride reaction with alcohol using an alkaline catalys t . (tamba, 2012). the basic catalyst used in the reaction may be a homogeneous or heterogeneous catalyst. homogeny catalys t s such as naoh and koh are commonly used for transesterification reactions. however, heterogeneous catalys t s are more interesting to study because the separation between the product and the catalyst is easy, and the catalyst can be reused so as to reduce production costs (lesbani et al., 2013). in addition, calcium oxide can be produced from bone fish and cow bone, as reported (ceria, 2013) from the research obtained calcium oxide catalyst with the best decomposition results is at temperatures 1000 º c and 1100 º c. then (amriana, 2014) makes cao catalyst from duck eggshell and produces the best decomposition of calcium oxide at a temperature of 900ºc. th e resulting catalyst (amriana, 2014) has been applied in the synthesis of biodiesel from cooking oil through transesterification reaction and yields biodiesel with a yield of 53.57% (% v / v). sueb (2014) produced a calcium oxide catalys t article history received: 21 july 2016 accepted: 30 semptember 2016 doi: 10.26554/sti.2016.1.1.1-7 from quail egg shell with a decomposition temperature of 900 º c, after application in biodiesel synthesis from cooking oil produced a yield of 55.71% (% v / v).based on the research that has been described above, in this study, calcium oxide catalys t from another source, namely the shell crab (portunus pelagicus). the crab shell was prepared and decomposed with various temperature variations. calcium oxide catalyst ob tained was applied in the synthesis of biodiesel from used cooking oil, palm oil and coconut oil. experimental section materials and instrumentation pycnometer, diffractometer xrd, spectrophotometer ftir shim adzu, and sem -edx jed-2300 analysis station brand jeol were used for characterization of material in this research . materials used in the study is crab shells, cooking oil, palm oil and coconut oil, methanol pa, ethanol pa, fenolptalin indicators , anhydrous sodium sulphate, potassium hydroxide, oxalic acid , iodine bromide, distilled water, sodium thiosulfate, phosphoric acid, carbon tetrachloride, reagents wijs, and starch . preliminary sampling and preparation of crab shells the crab shells were taken randomly from several sampling locations in palembang. the stored crab shell was washed and dried in an oven with a temperature of 100 ° c to remove water. dry crab shell was crushed and sieved to pass the size of 100 meshes. a fine shell of a small size of 100 meshes is characterized by x-ray diffraction. the fine shellfish shell of the sieve is ready for the next procedure. minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 2 preparation and characterization of calcium oxide from the shell of the crabs the crab shells that are sieved through a 100 mesh sieve for as much as 100 g were decomposed with furnace under oxygen atmospheric conditions at various temperature variations. the temperature variations used were 700, 800, 900, 1000 and 1100 ° c for 3 hours. after the cold the obtained solids were stored in the desiccator for 24 hours according to nakataniet al. 2009. characterization was done by using x-ray diffraction to see the metal oxide structure formed. the resulting characterizat i o n results are then compared to the standard jcbi calcium oxide data which is the standard for xrd pattern data. characterization of oxide of preparation result the best result of the decomposition process of the crab shell is marked by xrd pattern which is suitable and close to jcpds standard, then the result will be analyzed with ft-ir and sem spectrophotometer. sampling of waste cooking oil (wco), palm oil and coconut oil waste oil is taken from household waste in indralaya. w co obtained is cleaned of im purities by means of filtration and then stored in a container. clean cooking oil will be used in the transesterification process. while palm oil and coconut oil can be directly used. study of transesterification of wco, palm oil and coconut oil with catalytic preparation result into biodiesel the transesterification reaction was carried out using a 500 ml schlenk flask equipped with a pumpkin flap. a total of 100 ml of cooking oil, palm oil and coconut oil each added methanol p.a. as much as 40 ml followed by the addition of cao catalyst of the preparation result of a crab shell of 0.2 g. the reaction was heated at 65 ° c. for 3 hours. the reaction is stopped by putting a container containing ice water. the reaction product was left overnight for several phases followed by separation by addition of 1 ml of h3po4 for the neutralization process. distillate biodiesel products the results of the transesterification reaction are further distilled. warming of the product is performed by heating the mantle at a temperature of 65 ° c to separate the methanol solvent on the mixture and 100 ° c for separation by water. the product evaporates and separates the biodiesel fraction from steam to the condenser. the result of distillation is then measured for its volume qualitatively. determination of density of biodiesel product the density measurements were carried out in a water bath with a temperature of 25oc. aquadest as a standard was incorporated into a pyrometer that has been known to weigh, then weighed again. pycnometer containing the product, was soaked in a temperature-adjusted waterbath for approxim ately 15 minutes. after that the pycnometer is dried off outside the water bath and weighed. the same treatment is done for aquades as a comparison. the same procedure is also carried out for the determination of density on waste cooking oil, palm oil and coconut oil. density= 𝑾𝒑𝒓𝒐𝒅𝒖𝒄𝒕 𝑽𝒑𝒚𝒄𝒏𝒐𝒎𝒆𝒕𝒆𝒓 determination of viscosity test of biodiesel product (astm d-445) the biodiesel sample is inserted into the viscometer and then inserted in the water bath. the upper line of the viscometer is arranged so that the line is 3cm below the water level in the water bath, then covered with rubber and left for 1 hour. next the lid is opened and the sample is allowed to flow. the sample flow tim e is recorded from the first line to the second line in seconds. if the flow tim e is less than 200 seconds, then the determination is repeated using a viscometer with a smaller factor. the same procedure was performed for the determination of density in cooking oil, palm oil and coconut oil. viscosity formula: kv = f x t where : kv = kinematic viscosity f = viscometer factor t = flow tim e of example determination of acid numbers by titration method 5 g of biodiesel samples were weighed and then added with 10 ml ethanol, after stirring the sample to be boiled until boiling, after which it is stirred until completely dissolved. the resulting sample is titrated with pp indicator using a koh titrant to produce a pink color. the same procedure is performed on cooking oil, palm oil and coconut oil prior to transesterificat i o n as a preliminary treatment. the acid number formula: acid numbers = 𝐦𝐋 𝐊𝐎 𝐇 𝐱 𝐍 𝐊𝐎𝐇 𝐱 𝟓𝟔 ,𝟏 𝐒𝐚𝐦𝐩𝐥𝐞 𝐖𝐞𝐢𝐠𝐡𝐭 koh standarization a total of 102 mg of oxalic acid was included in erlenmeyer 250 ml and then added with 25 ml of distilled water. in the mixture is added pp indicator and titrated with koh which will be standardized until it was pink. repeat for three tim es. standard test for iod numbers (sni 04-7182-2006) biodiesel from transesterification reaction weighed as much as 0.5 g and then put into erlenmeyer. then 10 ml of chloroform solution and 25 ml of wijs reagent are added to the erlenmeyer, shaken until all oil is well blended and let stand in a dark room for 30 minutes. 10 ml of 15% ki solution added. the titration was carried out with 0.1 n na2s2o3 solutions and the indicator used was starch 1%, titration to a clear solution. the same procedure is also carried out for the determination of iodine quantities in cooking oil, palm oil and coconut oil. the iodine number is calculated by the formula: iod number = (𝑩−𝑪) 𝟏𝟐,𝟔𝟗 𝒙𝑵 𝑾 information : minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 3 c = volume of sodium tiosulfate solution spent in sample titration (ml) b = volume of sodium tiosulfate solution spent in blank titrations (ml) n = normalities of sodium tiosulfate solution w = the weight of the alkyl ester sample weighed for analysis (g) results and discussion preparation of calcium oxide from the shell of crabs preparation of calcium oxide from crab shell was done by decomposition process in a furnace done at variation of temperature starting from 700 ºc, 800 ºc, 900 ºc, 1000 ºc until 1100ºc, for 3 hours. the cao was derived from caco3 which decomposed due to heating at high temperature, but also to remove organic compounds contained in the crab shell. based on the result of decomposition, physical changes of crab shells powder before and after the decomposition can be seen in figure 1. figure 1. percentage of yield in various temperatures. based on figure 1, the result of each decomposition proces s with temperature variation shows the tendency of the higher heating temperature, the weight of the solid decreases. changes also occur in the color of crab shell powder. shell crab powder is reddish before decomposition, then the color turns grayish at a decomposition temperature of 700 º c and turns white by increasing the decomposition temperature. this happens because of the loss of organic compound s contained in the shell, after the process of decomposition with high temperatures. identification of calcium oxide preparation results of crab shell with xrd analysis the decomposition result of the crab shells was characterized by x-ray diffractometer, this measurement resulted in the diffraction pattern of calcium derived compounds such as cao, ca(oh)2, caco3, as the main compound. the diffractogram pattern of the resultant decomposition of the crab shell was matched with the joint committe powder diffracti o n standard (jcpds) diffraction pattern as a comparator or standard for obtaining pure cao. diffractogram of the standard cao compounds are presented in figure 2. while the diffractogram of cao compounds from the crab shell with various decomposition temperatures are presented in figure 3. based on figure 1 the result of decomposition of crab shells at temperatures of 700 º and 800 º c looks peak produced very far from jcpds standard. due to the decomposition of 700 º c and 800 º c the peaks of caco3 are still many even the peak with the highest intensity was the peak for caco3 region. while the peak for cao only appears with a weak intensity. for decomposition results at temperatures of 900 º c the appearan ce of peaks is in the four areas of cao with a value of 2θ close to the standard although the difference is not so great but the peak intensity produced increases very much. in addition to the peaks for cao that are increasingly close to jcpds standards at this decomposition temperature, the peaks showing the presence of caco3 and ca(oh)2 were decreasing. decomposition results at a temperature of 1000 º c the appearance of the highest intensity cao peak and closer to the jcpds standard diffractogram pattern. but unlike the diffraction patterns generated at the decomposition temperature of 1100 º c, although the peak areas produced at the same diffraction but the intensity are weakened , there is also a peak that states caco3 and ca(oh)2 which at the previous temperature was no longer visible. based on the intensity and value of 2θ obtained on each decomposition result the higher temperature the more caco 3 decomposes and thus more and more cao is formed, at a temperature of 700 º c the appearance of two medium -intensity cao peaks in the 2θ region approaching the jcpds standard ie at 32.1 º and 64.9 º with an intensity of 96 and 65, this indicates the presence of decomposing caco3. whereas at a decomposition temperature of 800 º c, the emerging cao peaks grew, at values of 2θ: 32.2 º, 37.4 º, 64.8 º, 67.5 º with an intensity of 223, 547, 44 and 68, this shows the more decomposed caco3, but it can also be seen by the decreasing of the peaks of caco3 that appears. figure 2. diffractogram for cao compound jcpds standard no. 00-043-1001 minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 4 2θ figure 3. diffractogram s of the crab shells decomposition at various temperatures decomposition results at temperatures of 900 ºc, cao peaks appear increasingly close to cao standards ie at 2θ: 32.3º, 37.5 º, 64.3 º, 67.5 º. however, these areas have sim ilarities with the decomposition at a temperature of 1000 ºc, the peak that appears at 2θ: 32.4 º, 37.5 º, 64.3 º, 67.5 º so as to determine the best between the two seen from the highest peak intensity, from the analysis results obtained the best decompositio n that is at temperature 1000 ºc with intensity 468, 1377, 230, 191. at decomposition temperature 1100 ºc, cao peak becomes weaker that is with intensity at 276, 855 , 122 and 102 at 2θ: 32.2 º, 37.4 º, 64.2 º, 67.4 º. based on the diffraction pattern obtained and matching with the existing jcpds standard then the solids taken with decomposition temperature 1000 ºc as the best decomposition result because the peak of cao on the decomposition at temperature 1000 ºc the highest intensity is 1377. further characterization is done by using spectrosco p y ft-ir in crab shells of decomposition at 1000 ºc and compared with standard cao. the value of 2θ for cao, ca(oh)2, caco3 showed the standard of jcpds is presented in table 1 as a comparison of the compound content in each treatment of temperature variation can be analyzed by observing in detail the diffractio n at 2 as presented in figure 3. the results of xrd diffraction pattern analysis of decomposition approaching cao standard in crab shell were identified using ftir spectrophotometer. characterization by ftir aim s to identify functional groups formed on solids of the preparation. in this research, the result of decomposition of shell crab at 1000 ° c and crab shells that has not been decomposed analyzed by ftir. the ftir spectra of measurement results is presented in figure 4. table 1. 2θ value for cao, ca(oh)2, caco3 standard compounds from jcpds. compound 2θ cao 34.2º 37.3º 58.3º 64.1º 67.3º caco3 29.4º 39.4º 43.2º 47.4º 48.5º ca(oh)2 28.6º 47.1º 50.8º source : (nakatani et al. 2009) figure 4 shows that there were functional groups in the 4004000 cm -1 wave region. this range of wavelengths can be divided into two main regions ie in the range of the wave number 4001000 cm -1 as the area for the identification of inorgani c compounds and the 1000-4000 cm -1 wave number range as the basis of organic compounds to facilitate the observation the absorption of calcium oxide which is the target compound is expected to be observed in the range of 250-400 cm -1 (gonzales et al., 2010). ca-o uptake bands on crab shell sample of decomposition at temperature 1000ºc is seen on 354,9 cm -1 area. the results of the analysis before decomposition also have peaks in the same area but the intensity increases after the decomposition process. the band was reinforced by the appearance of peaks on the wavelength regions 871,82 cm -1, and 956.69 cm -1. figure 4b also shows the vibration of 1049.28 cm 1 which predicted the vibration region for c-o. the o-c-o minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 5 stretching bond of carbonate appears at the peak at 1635,64 cm 1 wave numbers. in figure 4a there was a peak in the vibration region of 3448,72 cm -1 predicted to be the region for o-h, this was reinforced in the spectrum after the decomposition at 1000ºc resulting peak at 3641,6 cm -1 was the specific area for free o-h. the presence of the oh group indicated a peak matching of the sample vibrations analyzed by standard cao. the results of the analysis indicating the presence of oh groups of ca(oh) 2 identify the possibility of water adsorbed on the surface of cao, because cao is very easy to absorb water vapor from the air (grandos et al., 2007) .the data of the waveform of the preparation results shown by ft-ir supports xrd diffractio n pattern data. further identification is done by using sem-edx. identification of calcium oxide results of preliminary shell concrete by sem-edx analysis the best shell decomposition was at 1000 ºc, and for undecomposed solids, calcium oxide analysis is performed by using sem-edx. from the analysis results can be seen clearl y the difference between the two, as presented in figures 5. from figure 5b and d above the changes in the composition of crab shell before and after decomposition can be seen with edx analysis. prior to the decomposition process , the composition of shell crabs comprised of carbon 50.59%, magnesium 5.10%, p2o5 3.41%, cao 34.57%, cuo 3.68% and zno 2.65%. after decomposition at 1000 º c there was a decrease for some carbon components to 29.57%, zno 2.19%. but there was an increase in cao, magnesium, p2o5 and cuo to 49.71%, 6.39% and 8.39%, and 3.75%. this is because after the decomposition process with a high enough temperature, the compounds are decomposed into expected target compounds. synthesis of biodiesel by transesterification of w co, palm oil and coconut with calcium oxide catalyst decomposition result from shell of combination at temperature 1000oc calcium oxide resulting from decomposition process of crab shell at decomposition temperature of 1000 oc which has been characterized furthermore used as base catalyst in biodiesel synthesis through transesterification reaction of cooking oil, palm oil and coconut oil. the biodiesel product obtained from the transesterification reaction is in the upper layer, the top layer is removed and distilled. pure biodiesel produced as much as 40.71% of cooking oil, 58.57% of palm oil, and 67.85% of coconut oil. the biodiesel is then characterized by determination of density, viscosity, acid number and iodine number. characterization of biodiesel by transesterification of wco with calcium oxide catalyst decomposition result of the crab shell at temperature 1000 oc the results of analysis on biodiesel by determination of density, viscosity, acid number and iodine number are presented in table 2. biodiesel product weight test (astm d-1298) density provides information on how the fuel will work in a diesel engine. according to sni 04-7182-2006 density of diesel fuel specifications should be in the range 0.82 to 0.900 g/cm 3. tests were performed on biodiesel products, with an averag e value obtained for cooking oil of 0.8621 g/cm 3, for palm oil 0.8725 g/cm 3, and for coconut oil of 0.8688 g/cm 3. density for each oil prior to transesterification reaction yields 0.8900 g/cm 3 of cooking oil, palm oil 0.8731 g/cm 3, and coconut oil 0.8818 g/cm 3. the density values of biodiesel products obtained are included in the standard range of biodiesel from sni . wave numbers (cm -1) figure 4. ftir spectrum of crab shell (a) and decomposition result at 1000oc (b). viscosity value of biodiesel products (astm d-445) viscosity is defined as fluid resistance to the flow rate of an m m -sized capillary (sartika, 2009). viscosity for each oil as initial measurement before transesterification of cooking oil, palm oil and palm oil respectively 48.2516 mm 2/s(cst), 34.0600 m m 2/s(cst) and 21.6150 mm 2/s(cst). the result of viscosit y measurement on biodiesel product of synthetic from wnt is 5.27 mm 2/s(cst), palm oil 3.71 mm 2/s(cst), and coconut oil 2.45 m m 2/s(cst). based on the standard value for biodiesel at sni 047182-2006, the standard biodiesel standard viscosity value is 2.36.0 mm 2/s (cst). based on the characterization data obtained from the use of the calcium oxide catalyst from the crab shell of the decomposition at a temperature of 1000 º c yields a viscosit y value for biodiesel in accordance with sni assumed standard. acid numbers the result of acid number determination on biodiesel product with titration method got average value from repetition three tim es equal to 0.3069 mg/koh for cooking oil, 0.2423 mg/koh for palm oil and 0.2100 mg/koh for oil coconut . with preliminary measurement results for each oil of 6.8666 mg/koh for cooking oil, 5.6144 mg/koh of palm oil, and 2.6254 mg/koh of coconut oil. as the ratio of the acid value of each oil according to sni standard the maxim um of 0.8 mg/koh. from the data it can be concluded that the biodiesel product produced has the value of acid number in accord an ce with sni 04-7182-2006 standard. minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 6 . figure 5. sem and edx analysis results of crab shells (a), (b) and after it was decomposed at 1000º c (c), (d). table 2. data of biodiesel characterization result of synthetic from cooking oil, palm oil and coconut oil and biodiesel standard ba sed on sni 04-7182-2006. initial oil sample biodiesel product sample oil sample density (g cm -1) viscosity (mm 2/s) acid number (mg/koh) iod number (gi2/100g) density (g cm -1) viscosity (mm 2/s) acid number (mg/koh) iod number (gi2/100g) jelantah oil 0.8900 48.2516 6.8666 51. 66 0.8621 5.27 0.3069 39.48 palm oil 0.8731 34.0600 5.6144 45.92 0.8725 3.71 0.2423 36.12 coconut oil 0.8818 21.6150 2.6254 36.54 0.8688 2.49 0.2100 9.24 biodiesel standard 0.850.89 0.2-6.0 max 0.8 max 115 biodiesel product iod value (aocs cd 1-25) the result of determination of number of iod from biodiesel product got average value from repetition 3 tim es equal to 39,48 g i2/100g for cooking oil, 36.12 g i2/100g for palm oil, and 9.24 g i2/100g for oil coconut. the results of the analysis show that the iodine number of each biodiesel produced by synthesis is in accordance with the standard value of biodiesel set by sni. biodiesel with high iodine content exceeding the standard biodiesel quality standard 115 g i 2/100g will result in polymerization tendency and deposit formation in noozle injectors and piston rings at the tim e of decomposition (soerawidjaja, 2006). the iodine number of each oil prior to transesterification was 51.66 g i2/100g of cooking oil, 45.92 g i2/100g of palm oil and 36.54 g i2/100g of coconut oil. co nclusion the best decomposition temperature of crab shell at 1000 ºc. the results of xrd characterization, ft-ir decomposition of shrim p shells show the presence of cao, and sem-edx analysis shows differences in homogeneity of crab surface shell before and after decomposition. the quality of biodiesel produced from cooking oil, palm oil, and coconut oil meets the sni standard with density (0.8621-0.8725 g/cm 3), viscosit y (2.45-5.27 mm 2/s(cst), acid number (0.1944-0.2842 mg/koh), and iodine number (9.24-39.48 gi2/100g). biodiesel products from cooking oil, palm oil and coconut oil yield percent yield of 40.71%, 58.57%, and 67.85% (% v/v). references agrawal, s., singh b., sharma.y.c. 2011. exoskeleton of mollusk (pila globosa) as a heteregeneous catalyst for synthesis of biodisel using fring oil. industrial & engineering chemistry research.vol 51, 37:11875-11880. amriana, dessy. 2014. preparasi kalsium oksida dari cangkang telur bebek ( anas moscha ) untuk produksi biodiesel dari minyak jelantah. skripsi mahasiswa kim ia fmipa, universeitas sriwijaya minaria et al. / science and technology indonesia 1(1) 2016:1-7 @2016 published under the terms of the cc by nc sa 4.0 license 7 boey, peng-lim ., gaanty, p.m., & shafida, a.h.2009. biodiesel production via transesterifikasi of palm olein using waste mud crab (scylla serrata)shell as a heterogeneous catalyst.bioresource technology, vol 100: 632-6368. ceria, s.o. 2013. preparasi kalsium oksida dari tulang sapi dan tulang ikan sebagai katalis heterogen untuk sintesis biodiesel dari minyak jelantah. skripsi mahasiswa kim ia. universitas sriwijaya gonzales, m., hennandes, e., ascencio, j.a., pacheco, f., & pacheco, s.2010. hidroksiapatite cristal grown on a selulosa matrix using titanium alkokxide as a coupling agen. jurnal of material chemistry. vol.13: 2948-2951 granados, m. l., alonso, d. m., sadaba, i., and ocon, p. 2009. leaching and homogeneous contribution in liquid phase reaction catalysed by solids : the case of triglyceri d es methanolysis using cao. appl. catal. b-environ., 89 (1-2), 265-272. lesbani, a., palita, t., risfidian, m., fahmariyanti . 2013. preparation of calcium oxide from achatina fulica as catalyst for production of biodiesel from waste cooking oil. indo. j. chem, 13 (2), 176 – 180. ma, f., and hanna, m. a. 1999. biodiesel production ; a. review. bioresource technology, vol. 70: 1-115. nakatani, n., takamori, h., takeda, k., & sukugawa, h. 2009. transesterification of soyben oil using combusted oyster shell waste as a catalyst. bioresourse technology, vol.100: 15101513. sartika, d.2009. penentuan persen volume fraksi minyak mentah ( crude petroleum) dengan metode distilasi secara astm d-86 di pt.pertamina ep region sumatera field pangkalan susu . kim ia fmipa usu. medan. soerawidjaja, t.h. 2006. minyak lemak dan produk-produk kimia lain dari kelapa. program studi teknik kim ia. bandung. sueb, abi. 2014. aplikasi kalsium oksida hasil preparasi dari cangkang telur puyuh sebagai katalis dalam sintesis biodiesel dari minyak jelantah. skripsi mahasiswa kim ia fmipa, universitas sriwijaya tamba, p. 2012. studi preparasi katalis oksida logam dari cangkang bekicot (achatina fulica) dan aplikasinya dalam sintesis biodiesel dari minyak jelantah. skripsi mahasiswa kimia fmipa, universitas sriwijaya. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper determining the number of connected vertex labeled graphs of order seven without loops by observing the patterns of formula for lower order graphs with similar property muslim ansori1, wamiliana1*, fadila cahya puri1 1department of mathematics, faculty of mathematics and natural science, universitas lampung, bandar lampung, 35145, indonesia, *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstractgiven n vertices and m edges, m ≥ 1, and for every vertex is given a label, there are lots of graphs that can be obtained. the graphsobtained may be simple or not simple, connected or disconnected. a graph g(v,e) is called simple if g(v,e) not containing loopsnor paralel edges. an edge which has the same end vertex is called a loop, and paralel edges are two or more edges which connectthe same set of vertices. let n(g7,m,t) as the number of connected vertex labeled graphs of order seven with m vertices and t (t is the number edges that connect different pair of vertices). the result shows that n(g7,m,t) = ct c (m−1)t−1 , with c6=6727, c7=30160 , c8=30765, c9=21000, c10=28364, c11=26880, c12=26460, c13=20790, c14=10290, c15= 8022, c16=2940, c17=4417, c18=2835, c19=210, c20= 21, c21=1. keywordsgraph, connected, vertex, labeled, order, loops received: 7 july 2021, accepted: 4 october 2021 https://doi.org/10.26554/sti.2021.6.4.328-336 1. introduction graph theory emerged as a new eld in mathematics in 1736 after leonhard euler gave solution to the konigsberg problem, graph theory was used widely in many real-life applications, especially as problems representation. a graph g (v,e) is a structure which consists of a set v={v1, v2, . . . , vn} of vertices, where v ≠ ∅, and a set of edges e=ei j | i, j ∈ v which connect the vertices of v. usually the vertices are used to represent cities, depots, train stations, airports, etc., while edges are usually used to represent roads, train tracks, ight paths, etc. a number ci j ≥ 0 can be assigned to the edge ei j as a nonformal information which can represent the distance, time, cost, ow, etc. because the exibility of how to draw a graph, where there is no restriction in drawing an edge (can be a straight line, a curve, or other line), graph becomes an interesting structure to cope with, especially to represent the problem for easily visualization. some of graph terminologies that commonly used in application is the concept of tree, where tree is a connected graph without cycle. some applications that use graph theoretical concept as problems representation include applications in biology, chemistry, engineering, computer science, economics, agriculture, and others. forexample, in biology, a leaf labeled tree was used to represent the evolutionary history of a set of taxa which is called as phylogenetic tree (huson and bryant, 2006; brandes and cornelsen, 2009), and mathur and adlakha (2016) used combinedtree torepresentdna, inchemistry/pharmaceutical, gramatica et al. (2014) used graph concept to describe or represent the possible modes of action for any given pharmacological compound; in engineering and computer science, hsu and lin (2009) exposed a lot of graph theoretical concepts including hamiltonian circuits with relation in network design, al etaiwi (2014) in order to generate a complex cipher text used the concepts minimum spanning tree, complete graph and cycle graph, priyadarsini (2015) investigate the use of graph theory concept, extremal and expander graphs in designing some ciphers, while ni et al. (2021) use bipartite and corona graphs to create ciphers; in economics, álvarez and ehnts (2015) used directed graph to represent the dynamic closures of the accounting structure; in agriculture, kawakura and shibasaki (2018) used graph theory concepts to group agricultural workers engaging in manual tasks, kannimuthu et al. (2020) use graph coloring to optimize farmer’s objective, and many more. in 1857 cayley enumerated the isomer of cnh2n+2 using the concept of tree (cayley, 1874), and followed by slomenski (1964) who used graph theory to calculate additive structural https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.328-336&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.328-336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 properties of hydrocarbon. bona (2007) discussed how to enumerate trees and forest. if we are given n vertices and m edges, then lots of graphs can be obtained using that information. the graph obtained may be simple graph which does not contain loop nor parallel edges, or maybe not simple. moreover, the graph obtained also may be connected or disconnected. for connected vertex labeled graph, the number of graph of order ve with maximum number of paralel edges is ve without loopswas investigatedbywamilianaetal. (2019), andthenumber of graph of order six without paralel edges with ten loops maximum also investigated by wamiliana et al. (2020). puri et al. (2021) investigated the number of graphs of order six with maximum thirty edges without loops. for disconnected vertex labeled graph, wamiliana et al. (2016) investigated the number of graph of order ve without paralel edges, amanto et al. (2017) gave the formula for graph of order maximal four, putri et al. (2021) observed and gave formula for the number graphs of order six without loops and may contain maximum twenty parallel edges, while pertiwi et al. (2021) proposed the formula for counting the number graph of order six without loops, especially when the graph obtained only contains maximum seven loops and the number of non loop edges is even. in this study, by observing the patterns of the formula of the number of connected vertex labeled graphs of order ve and order six containing no loops, the formula of graphs of order seven with similar property will be discussed. we organized this paper as follows: section i is introduction that describes about what is graph, some applications of graphs, and some researches related with this study. in section ii observation and investigation will be discussed while result and discussion is provided in section iii, and conclusion in given in section iv. 2. observation and investigation given a graph g(v,e) where n =|v| = 7 and g is connected. because g is connected, then the number of edges m = |e| ≥ 6. every vertex in g is labeled, therefore graphs g1 and g2 in figure 1 are two dierent graphs even though both graphs look similar. figure 1. two dierent graphs that look the same but dierent because of the vertex labeling denote n(gn,m,t) as the number of connected vertex labeled graphs containing no loops of order n, m edges and t, where t is the number of edges that connect dierent pairs of vertices in g. edges that connect the same pair of vertices is counted as one. moreover, isomorphics graphs are counted as one graph. the result on table 1 for n=5 and are obtained from wamiliana et al. (2019), and for n=6 from and puri et al. (2021). from table 1 we know that for n = 5, the maximum number of t is 10, and for n= 6 is 15, and since the graph is connected, then m ≥ 4 for n = 5, and m ≥ 5 for n =6. by observing table 1 we found that there are patterns between those two order graphs. notice that, for every t, the formula only dier on the coecients. let ct is contant with t= 6,7,...,21. by using the patterns on table 1, we predict that the formula fororder seven as ct c (m−1) t−1 . note that for order 7, maximum t is 21. 3. results and discussion given n=7, t and m, the number of graphs of order seven, connected, and vertex labelled are obtained by: pattern construction, grouping the patterns in term of m and t, and then calculate the graphs. starting with t=6, we construct for m ≥ 6. the process continue with t=7 until t=21 (maximum possible t for n=7). table 2 shows some possible patterns for t=n-1. note that we do not put all possible patterns here due to space limitation, for example, for t=n-1 and m= n, the paralel edges maybe connect vertex v1 and v2 or v4 and v5, and so on, and for t=n-1 and m=n+1, that is possible the paralel edges only on one pair of vertices, for example, there are three edges that connect vertex v1 and v2, etc. the number of graphs obtained is given in table 3. by observing the number in every column, table 3 can be rewrite as in table 4. by grouping the graphs by m and t, we notice that every column of table 4 constitute patterns. note that in the table 3 and 4 we are not inputting all the numbers of graph obtained because t is xed in every column and adding more edges only adding more paralel edges on t, and the pattern continues for the next m, for example: for t= 6, m ≥ 6 we only input the number until m= 12 and the pattern is 1, 6, 21, 56, 126, 252, 462 (if adding more m, the pattern becomes 1, 6, 21, 56, 126, 252, 462, 792, 1287, 2002,...). the sequence of numbers that appear in the rst column (t= 6) is 1, 6, 21, 56, 126, 252, 462 and that number is multiplied by 6727. therefore we can claim that the value of c6 in table 3 is 6727. © 2021 the authors. page 329 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 table 1. the formula of the number of connected vertex labeled graph of order n , n = 5, 6 , m edges and t, where t is the number of edges that connect dierent pairs of vertices in graph, and containing no loops t n 5 6 4 n (g5,m,4) = 125 × c (m−1) 3 5 n (g5,m,5) = 222 × c (m−1) 4 n (g6,m,5) = 1296 × c (m−1) 4 6 n (g5,m,6) = 205 × c (m−1) 5 n (g6,m,6) = 1980 × c (m−1) 5 7 n (g5,m,7) = 110 × c (m−1) 6 n (g6,m,7) = 3330 × c (m−1) 6 8 n (g5,m,8) = 45 × c (m−1) 7 n (g6,m,8) = 4620 × c (m−1) 7 9 n (g5,m,9) = 10 × c (m−1) 8 n (g6,m,9) = 6660 × c (m−1) 8 10 n (g5,m,10) = 1 × c (m−1) 9 n (g6,m,10) = 2640 × c (m−1) 9 11 n (g6,m,11) = 1155 × c (m−1) 10 12 n (g6,m,12) = 420 × c (m−1) 11 13 n (g6,m,13) = 150 × c (m−1) 12 14 n (g6,m,14) = 15 × c (m−1) 13 15 n (g6,m,13) = 1 × c (m−1) 14 table 2. some possible patterns for t=n-1 (n=7) table 3. grouping the number of connected vertex labeled graph of order seven without loops by m and t m the number of connected vertex labeled graphs of order seven without loops t 6 7 8 9 10 11 6 6727 7 40362 30160 8 141267 211120 30765 9 376712 844480 246120 21000 10 847602 2533440 1107540 189000 28364 11 1695204 6333600 3691800 945000 283640 26880 12 3107874 13933920 10152450 3465000 1560020 295680 13 27867840 24365880 10395000 6240080 1774080 14 51754560 52792740 27027000 20280260 7687680 15 105585480 63063000 56784728 26906880 16 197972775 135135000 141961820 80720640 17 270270000 324484160 215255040 18 510510000 689528840 522762240 19 1379057680 1176215040 20 2620209592 2483120640 21 4966241280 22 9481006080 © 2021 the authors. page 330 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 m the number of connected vertex labeled graphs of order seven without loops t 12 13 14 15 16 12 26460 13 317520 20790 14 2063880 270270 10290 15 9631440 1891890 144060 8022 16 36117900 9459450 1080450 120330 5460 17 115577280 37837800 5762400 962640 87360 18 327468960 128648520 24490200 5454960 742560 19 842063040 385945560 88164720 24547320 4455360 20 1999899720 1047566520 279188280 93279816 21162960 21 4444221600 2618916300 797680800 310932720 84651840 22 9332865360 6110804700 2093912100 932798160 296281440 23 18665730720 13443770340 5118451800 2565194940 931170240 24 35775983880 28109701620 11772439140 6555498180 2677114440 25 56219403240 25685321760 15733195632 7138971840 26 108114237000 53511087000 35757262800 17847429600 27 107022174000 77474069400 42184833600 28 206399907000 160907682600 94915875600 29 321815365200 204434193600 30 622176372720 423470829600 31 846941659200 32 1640949464700 m the number of connected vertex labeled graphs of order seven without loops t 17 18 19 20 21 17 4417 18 75089 2835 19 675801 51030 210 20 4280073 484785 3990 21 21 21400365 3231900 39900 420 1 22 89881533 16967475 279300 4410 21 23 329565621 74656890 1536150 32340 231 24 1082858469 286184745 7066290 185955 1771 25 3248575407 981204840 28265160 892584 10626 26 9023820575 3066265125 100947000 3719100 53130 27 23461933495 8858099250 328077750 13813800 230230 28 57588382215 23916867975 984233250 46621575 888030 29 134372891835 60879300300 2755853100 145044900 3108105 30 299754912555 147124975725 7265430900 420630210 10015005 31 642331955475 339519174750 18163577250 1147173300 30045015 32 1327486041315 751792458375 43313145750 2963531025 84672315 33 2654972082630 1603823911200 99001476000 7294845600 225792840 34 5153769336870 3307886816850 217803247200 17194993200 573166440 35 6615773633700 462831900300 38975317920 1391975640 36 12864004287750 952889206500 85258507950 3247943160 37 1905778413000 180547428600 7307872110 38 3711252699000 371125269900 15905368710 39 742250539800 33578000610 40 1447388552610 68923264410 41 137846528820 42 269128937220 © 2021 the authors. page 331 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 table 4. another form of table 3 m the number of connected vertex labeled graphs of order seven without loops t 6 7 8 9 10 11 6 1 ×6727 7 6 ×6727 1×30160 8 21×6727 7×30160 1 ×30765 9 56×6727 28×30160 8 ×30765 1×21000 10 126×6727 84×30160 36 ×30765 9 ×21000 1 ×28364 11 252×6727 210×30160 120 ×30765 45 ×21000 10 ×28364 1× 26880 12 462×6727 462×30160 330 ×30765 165 ×21000 55 ×28364 11 × 26880 13 924×30160 792 ×30765 495 ×21000 220 ×28364 66 × 26880 14 1716×30160 1716 ×30765 1287 ×21000 715 ×28364 286 × 26880 15 3432 ×30765 3003×21000 2002 ×28364 1001 × 26880 16 6435×30765 6435×21000 5005×28364 3003× 26880 17 12870×21000 11440×28364 8008× 26880 18 24310×21000 24310×28364 19448× 26880 19 48620×28364 43758× 26880 20 92378×28364 92378× 26880 21 184756× 26880 22 352716× 26880 m the number of connected vertex labeled graphs of order seven without loops t 12 13 14 15 16 12 1×26460 13 12×26460 1×20790 14 78×26460 13×20790 1×10290 15 364×26460 91×20790 14×10290 1×8022 16 1365×26460 455×20790 105×10290 15×8022 1×2940 17 4368×26460 1820×20790 560×10290 120×8022 16×2940 18 12376×26460 6188×20790 2380×10290 680×8022 136×2940 19 31824×26460 18564×20790 8568×10290 3060×8022 816×2940 20 75582×26460 50388×20790 27132×10290 11628×8022 3876×2940 21 167960×26460 125970×20790 77520×10290 38760×8022 15504×2940 22 352716×26460 293930×20790 203490×10290 116280×8022 54264×2940 23 705432×26460 646646×20790 497420×10290 319770×8022 170544×2940 24 1352078×26460 1352078×20790 1144066×10290 817190×8022 490314×2940 25 2704156×20790 2496144×10290 1961256×8022 1307504×2940 26 5200300×20790 5200300×10290 4457400×8022 3268760×2940 27 10400600×10290 9657700×8022 7726160×2940 28 20058300×10290 20058300×8022 17383860×2940 29 40116600×8022 37442160×2940 30 77558760×8022 77558760×2940 31 155117520×2940 32 300540195×2940 result 1: given n = 7, m ≥ 6, t= 6, the number of connected graphs of order seven containing no loops is n (g7,m,6) = 6727 × c (m−1)5 . proof: look at the sequence of numbers above. it can be seen that from the sequence above that the xed dierence occur on the fth level. therefore the polynomial that can represent this sequence is polynomial of order ve: © 2021 the authors. page 332 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 m the number of connected vertex labeled graphs of order seven t 17 18 19 20 21 17 1×4417 18 17×4417 1×2835 19 153×4417 18×2835 1×210 20 969×4417 171×2835 19×210 1×21 21 4845×4417 1140×2835 190×210 20×21 1×1 22 20349×4417 5985×2835 1330×210 210×21 21×1 23 74613×4417 26334×2835 7315×210 1540×21 231×1 24 245157×4417 100947×2835 33649×210 8855×21 1771×1 25 735471×4417 346104×2835 134596×210 42504×21 10626×1 26 2042975×4417 1081575×2835 480700×210 177100×21 53130×1 27 5311735×4417 3124550×2835 1562275×210 657800×21 230230×1 28 13037895×4417 8436285×2835 4686825×210 2220075×21 888030×1 29 30421755×4417 21474180×2835 13123110×210 6906900×21 3108105×1 30 67863915×4417 51895935×2835 34597290×210 20030010×21 10015005×1 31 145422675×4417 119759850×2835 86493225×210 54627300×21 30045015×1 32 300540195×4417 265182525×2835 206253075×210 141120525×21 84672315×1 33 601080390×4417 565722720×2835 471435600×210 347373600×21 225792840×1 34 1166803110×4417 1166803110×2835 1037158320×210 818809200×21 573166440×1 35 2333606220×2835 2203961430×210 1855967520×21 1391975640×1 36 4537567650×2835 4537567650×210 4059928950×21 3247943160×1 37 9075135300×210 8597496600×21 7307872110×1 38 17672631900×210 17672631900×21 15905368710×1 39 35345263800×21 33578000610×1 40 68923264410×21 68923264410×1 41 137846528820×1 42 269128937220×1 p5(m) = a5m5 + a4m4 + a3m3 + a2m2 + a1m + a0 substitute m = 6, 7, 8, 9, 10, 11 to the equation we get the following: 6727 = 7776a5 + 1296a4 + 216a3 + 36a2 + 6a1 + a0 (1) 40362 = 16807a5 +2401a4 +343a3 +49a2 +7a1 + a0 (2) 141267 = 32768a5 +4096a4 +512a3 +64a2 +8a1 +a0 (3) 376712 = 59049a5 +6561a4 +729a3 +81a2 +9a1 +a0 (4) 847602 = 100000a5+10000a4+1000a3+100a2+10a1+a0 (5) 1695204 = 161051a5 + 14641a4 + 1331a3 + 121a2+ 11a1 + a0 (6) solving this system of linear equations we get a5 = 6727 120 , a4 = −100905120 , a3 = 571795 120 , a2 = − 1513575 120 , a1 = 1843198 120 and a0 = −807239120 p5(m) = a5m5 + a4m4 + a3m3 + a2m2 + a1m + a0 = 6727 120 m5 − 100905 120 m4 + 571795 120 m3 − 1513575 120 m2 + 1843198 120 m − 807239 120 = 6727 120 (m5 − 15m4 + 85m3 − 225m2 + 274m − 120) = 6727 120 (m − 1)(m − 2)(m − 3)(m − 4)(m − 5) = 6727 × (m − 1)(m − 2)(m − 3)(m − 4)(m − 5) (5 × 4 × 3 × 2 × 1) = 6727 × c (m−1)5 (7) for t=7, we can see from table 4 that the sequence of numbers is 1, 7, 28, 84, 210, 462, 924, 1716. © 2021 the authors. page 333 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 result 2: given n = 7, m ≥ 6, t= 7, the number of connected graphs of order seven containing no loops is n (g7,m,7) = 30160 × c (m−1)6 . proof: look at the sequence of numbers above. it can be seen that from the sequence above that the xed dierence occur on the sixth level. therefore the polynomial that can represent this sequence is polynomial of order six: p6(m) = a6m6 + a5m5 + a4m4 + a3m3 + a2m2 + a1m + a0 substitute m = 7, 8, 9, 10, 11, 12, 13 to the equation we get the following: 30160 = 117649a6+16807a5+2401a4+343a3+49a2+7a1+a0 (8) 211120 = 262144a6+32768a5+4096a4+512a3+64a2+8a1+a0 (9) 844480 = 531441a6+59049a5+6561a4+729a3+81a2+9a1+a0 (10) 2533440 = 1000000a6 + 100000a5 + 10000a4 + 1000a3+ 100a2 + 10a1 + a0 (11) 6333600 = 1771561a6 + 161051a5 + 14641a4 + 1331a3+ 121a2 + 11a1 + a0 (12) 13933920 = 2985984a6 + 248832a5 + 20736a4 + 1728a3 + 144a2 + 12a1 + a0 (13) 27867840 = 4826809a6 + 371293a5 + 28561a4 + 2197a3 + 169a2 + 13a1 + a0 (14) solving this system of linear equations we get a6 = 30160 720 , a5 = −633360720 , a4 = 5278000 720 , a3 = − 22167600 720 , a2 = 48979840 720 , a1 = −53202240720 and a0 = 21715200 720 therefore p6(m) = a6m6 + a5m5 + a4m4 + a3m3 + a2m2 + a1m + a0 = 30160 720 m6 − 633360/720 720 m5 + 5278000 720 m4 − 22167600 720 m3 + 48979840 720 m2 − 53202240 720 m + 21715200 720 = 30160 720 (m6 − 21m5 + 175m4 − 735m3 + 1624m2 − 1764m + 720) = 30160 720 (m − 1)(m − 2)(m − 3)(m − 4)(m − 5)(m − 6) = 30160 × (m − 1)(m − 2)(m − 3)(m − 4)(m − 5)(m − 6) (6 × 5 × 4 × 3 × 2 × 1) = 30160 × c (m−1)6 (15) doing with similar manner we get the following results: for n=7, m ≥ 8, t =8, n(g7,m,8) = 30765 × c (m−1) 7 for n=7, m ≥ 9, t =9, n(g7,m,9) = 21000 × c (m−1) 8 for n=7, m ≥ 10, t =10, n(g7,m,10) = 28364 × c (m−1) 9 for n=7, m ≥ 11, t =11, n(g7,m,11) = 26880 × c (m−1) 10 for n=7, m ≥ 12, t =12, n(g7,m,12) = 26460 × c (m−1) 11 for n=7, m ≥ 13, t =13, n(g7,m,13) = 20790 × c (m−1) 12 for n=7, m ≥ 14, t =14, n(g7,m,14) = 10290 × c (m−1) 13 for n=7, m ≥ 15, t =15, n(g7,m,15) = 8022 × c (m−1) 14 for n=7, m ≥ 16, t =16, n(g7,m,16) = 2940 × c (m−1) 15 for n=7, m ≥ 17, t =17, n(g7,m,17) = 4417 × c (m−1) 16 for n=7, m ≥ 18, t =18, n(g7,m,18) = 2835 × c (m−1) 17 for n=7, m ≥ 19, t =19, n(g7,m,19) = 210 × c (m−1) 18 for n=7, m ≥ 20, t =20, n(g7,m,20) = 21 × c (m−1) 19 for n=7, m ≥ 21, t =21, n(g7,m,21) = 1 × c (m−1) 20 base on these result, we get table 5. from table 5 it can be seen that for every t, the formula consist of c (m−1)t−1 , and the dierence is on ct. © 2021 the authors. page 334 of 336 ansori et. al. science and technology indonesia, 6 (2021) 328-336 table 5. comparison for the number of connected vertex labeled graphs of order five, six, and seven containing no loops t n 5 6 7 4 n(g5,m,4) = 125 × c (m−1) 3 5 n(g5,m,5) = 222 × c (m−1) 4 n(g6,m,5) = 1296 × c (m−1) 4 6 n(g5,m,6) = 205 × c (m−1) 5 n(g6,m,6) = 1980 × c (m−1) 5 n(g7,m,6) = 6727 × c (m−1) 5 7 n(g5,m,7) = 110 × c (m−1) 6 n(g6,m,7) = 3330 × c (m−1) 6 n(g7,m,7) = 30160 × c (m−1) 6 8 n(g5,m,8) = 45 × c (m−1) 7 n(g6,m,8) = 4620 × c (m−1) 7 n(g7,m,8) = 30765 × c (m−1) 7 9 n(g5,m,9) = 10 × c (m−1) 8 n(g6,m,9) = 6660 × c (m−1) 8 n(g7,m,9) = 21000 × c (m−1) 8 10 n(g5,m,10) = 1 × c (m−1) 9 n(g6,m,10) = 2640 × c (m−1) 9 n(g7,m,10) = 28634 × c (m−1) 9 11 n(g6,m,11) = 1155 × c (m−1) 10 n(g7,m,11) = 26880 × c (m−1) 10 12 n(g6,m,12) = 420 × c (m−1) 11 n(g7,m,12) = 26460 × c (m−1) 11 13 n(g6,m,13) = 150 × c (m−1) 12 n(g7,m,13) = 20790 × c (m−1) 12 14 n(g6,m,14) = 15 × c (m−1) 13 n(g7,m,14) = 10290 × c (m−1) 13 15 n(g6,m,13) = 1 × c (m−1) 14 n(g7,m,15) = 8022 × c (m−1) 14 16 n(g7,m,16) = 2940 × c (m−1) 15 17 n(g7,m,17) = 4417 × c (m−1) 16 18 n(g7,m,18) = 2835 × c (m−1) 17 19 n(g7,m,19) = 210 × c (m−1) 18 20 n(g7,m,20) = 21 × c (m−1) 19 21 n(g7,m,21) = 1 × c (m−1) 20 4. conclusions from the discussion above we can conclude that the formula to count the number of connected vertex labeled graph of order seven has a similar pattern with the lower order graph with the similar property. the dierence of the formulas is on the coecient for every t. the result shows that the number of connected vertex labeled graphs of order seven containing no loops is n(g7,m,t)= ct c (m−1) t−1 , with c6=6727, c7= 30160 , c8=30765, c9=21000, c10=28364, 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science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 4, no. 1, january 2019 research paper effect of dilute acid alkaline pretreatment on rice husk composition and hydrodynamic modeling with cfd novia1*, vishnu k pareek2, hermansyah3, asyeni miftahul jannah1 1departement of chemical engineering, faculty of engineering, universitas sriwijaya, indonesia 2western australian school of mines: minerals, energy and chemical engineering, curtin university, australia 3departement of chemical science, mathematics and science faculty, universitas sriwijaya, indonesia *corresponding author: novia@ft.unsri.ac.id abstract the high cellulosic content of rice husk can be utilized as a feedstock for pulp and biofuel. pretreatment is necessary to break the bonds in the complex lignocellulose matrices addressing the cellulose access. this work aims to utilize the rice husk using dilute acid and alkaline pretreatment experimentally and cfd modeling. the study consists of three series of research. the first stage was the dilute acid pretreatment with sulfuric acid concentration of 1% to 5% (v/v) at 85°c for 60 minutes, and alkaline pretreatment with naoh concentration of 1% to 5% (w/v) at 85oc for 30 minutes separately. the second stage used the combination of both pretreatment. moreover the last stage of research was hydrodynamic modeling of pretreatment process by cfd (ansys fluent 16). the experimental results showed that the lowest lignin content after acid pretreatment was about 10.74%. alkaline pretreatment produced the lowest lignin content of 4.35%. the highest cellulose content was 66.75 % for acid-alkaline pretreatment. the lowest content of lignin was about 6.09% for acid-alkaline pretreatment. the lowest performance of alkaline pretreatment on hws (hot water solubility) of about 7.34% can be enhanced to 9.71% by using a combination alkaline-acid. the combined pretreatments result hemicellulose of about 9.59% (alkaline-acid) and 9.27% (acid-alkaline). modeling results showed that the mixing area had the minimum pressure of about -6250 pa which is vortex leading minimum efficiency of mixing. the rice husk flowed upward to the upper level and mixed with reagent in the perfect mixing. keywords alkaline pretreatment, cfd modeling, dilute acid pretreatment, lignin, rice husk received: 17 october 2018, accepted: 12 january 2019 https://doi.org/10.26554/sti.2019.4.1.18-23 1. introduction programs on energy utilization have been sustained by �nding other kinds of renewable energy. several studies relating to the conversion of lignocellulose biomass as a raw material to produce bioethanol have been implemented (chen et al., 2011; hermansyah et al., 2015; karimi et al., 2006; novia et al., 2017; sudiyani et al., 2017; xavier et al., 2010). the conversion of bioethanol is still challenging. the lignin component in lignocellulose biomass must be eliminated in order to enable the digestibility of enzymatic hydrolysis. pretreatment is the most important step to reduce lignin and hemicellulose, to decrease the crystallinity of cellulose, and to improve the materials porosity (karimi et al., 2006). it is needed to change the structure of cellulosic biomass, making the cellulose more porous to enzymes which can alter the polymers of carbohydrate into fermentable sugars (mosier, 2005). after pretreatment, cellulose and hemicellulose are hydrolyzed to monomeric sugars. the pretreatment needs higher cost, so the best pretreatment can reduce the amount of chemicals for hydrolyzed. pretreatment also enhance the glucose yield. unpretreated samples gives lower than 20 %, using the pretreatment main process the glucose yield to about 90% (hamelinck et al., 2005). methods for the pretreatment of lignocellulose biomass to increase the hydrolysis have been studied: steam explosion and alkaline peroxide (cara, 2006; fang et al., 2010; ohgren et al., 2007); alkaline pretreatment (harun et al., 2011; mcintosh and vancov, 2010); and hydrothermal pretreatment (kaparaju and felby, 2010; kumar et al., 2011; thomsen et al., 2008). these technologies use extreme operating conditions of reaction with a greatly capital cost, highly processing fees and large investment risks (li et al., 2009). several pretreatment methods create strong acidic, poisonous materials in the preserved lignocellulose and inhibit mixtures for hydrolysis and following fermentation of ethanol. in addition, alkaline pretreatment was demonstrated to be more suitable on agricultural residues https://doi.org/10.26554/sti.2019.4.1.18-23 novia et. al. science and technology indonesia, 4 (2019) 18-23 than on materials of wood (taherzadeh et al., 2008). it also selectively reduces the lignin portion. pretreatment of alkali apply at lower temperatures and pressures compared to other pretreatment methods (mosier, 2005). the lime pretreatment process uses slurring the lime with water, showering it onto the biomass material and keeping the material for a particular duration, generally from days to weeks (mosier, 2005). ammonia has been usually used in alkali pretreatments; its use produces many environmental problems due to the recovering processes that must also be carried out along with this pretreatment. reducing hemicellulose and lignin content could highly increase enzyme digestibility by enhancing the enzyme accessibility to cellulose. pretreatment with dilute sulfuric acid followed by aqueous ammonia would then be required for the e�ective hydrolysis and lignin separation. with the bene�ts of dilute acid and alkaline method, this work investigated the combination of dilute acid-alkaline pretreatment to eliminate the lignin component in rice husk. pretreatment is a high cost process to allow lignocellulose biomass to be utilized to become an alternative fuels. however it has the possibility to increase the e�ectiveness and decreasing of the fee through more study and advance. hydrodynamic simulation of the alkaline-dilute acid pretreatment was performed using the computational �uid dynamics (cfd) modeling (ansys fluent 16). the fundamental processes that occur in the pretreatment process have been investigated. numerous researches (novia et al., 2007, 2017; cundari, 2016) are being applied to advance the computational methods appropriate for pairing the many crucial characteristics of chemistry and physics in a procedure that is e�ective enough for explaining the pretreatment problems. cfd modeling can o�er a huge scope of information for the design of pretreatment reactor. the use of cfd modeling can therefore decrease the cost of time-consuming experimental research. 2. experimental section 2.1 materials the rice husk samples were obtained from nearby (south sumatera). they were stored in plastic bags at 5oc, after determination of moisture content. the rice husks were collected from the location of inderalaya, south sumatera province, indonesia. then they were air-dried and kept at room temperature. they were crushed and put through a sieve tray (less than 0.8 mm). 2.2 methods 2.2.1 experimental method of dilute acid pretreatment lignocellulose rice husks were pretreated by the following procedure. each dry rice husk, of about 30 g, was fed into a stirred reactor of 500 ml and blended with 150 ml of sulfuric acid (h2so4) with various concentration of 1% to 5% (v/v). the mixture was kept warm in a rotary air bath at a speed of 500 rpm and temperature of 85°c for 30 min. the mixture was inserted in an autoclave at a temperature of 121°c for 30 min. the mixture was then put into 1l of pre-cold acetone and blended carefully. the slurry was separated using centrifuge at a speed of 8000 rpm. after 10 min of time, the �ltrate was gathered. the residue remains was rinsed in 1l of water and separated. the component of lignin before and after dilute-acid pretreatment was analyzed by a standard method of chesson (datta 1981). scanning electron microscope (sem) micrographs of cross section rice husk before and after pretreatment were taken using sem-edx microscope phenom pro x. 2.2.2 experimental method of dilute acid-alkaline pretreatment dilute-acid pretreated samples were followed by alkaline pretreatment to improve the removal percentage of lignin content in the samples 2.2.3 experimental method of alkaline-dilute acid pretreatment alkaline pretreated samples were followed by dilute-acid pretreatment to reduce percentage of lignin content in the samples 2.2.4 modeling of dilute acid-alkaline pretreatment by using cfd the cfd simulations were carried out by the euler-granular multiphase model available in the commercial cfd software (ansys fluent 16.0 documentation 2015). simpli�cation assumption is each phase coincides at every grid in domain in the form of interpenetrating continua. the mass conservation of phase i (i = �uid, solid): ∂ ∂t (ρiεi)+o• (ρiεiui)= ri (1) where, ε f + εs = 1 the conservation of momentum of phase i (i = �uid, k = solid, k , i): ∂ ∂t (ρiεiui)+o•(ρiεiuiui)=−εiop+o•τi+ρiεig−β(ui−uk) (2) the conservation of energy for phase i gives: ∂ ∂t (εi ρihi)+o•(εi ρiuihi)=−εi ∂pi ∂t +τi : oui−oqi+si (3) with, hi = ∑ i εi t∫ tref cpidt (4) for the drag force formulation, we use the syamlal-o’brian model (ansys fluent 16.0 documentation 2015) : β = 3 4 cd εsεg v2r,s ρg ds ( res vr,s ) ��us −ug�� (5) © 2019 the authors. page 19 of 23 novia et. al. science and technology indonesia, 4 (2019) 18-23 the drag coe�cient, cd is given by: cd = ©­­«0.63+ 4.8√ res vr,s ª®®¬ 2 (6) res = ρgds ��us −ug�� µg (7) the terminal velocity correlation for the solid phase: vr,s = 0.5a−0.03res+0.5 √ (0.06res)2 +0.12res(2b− a)+ a2 (8) where, a = ε4.14g (9) b = 0.8ε1.28g f orεg ≤ 0.85 (10) b = 0.8ε2.65g f orεg > 0.85 (11) solid pressure. the solids phase pressure (ps) contains a kinetic term and the particle collisions term. ps = (1+2(1+es)esgo)εs ρsθs = ρsεsθs+2go ρsε 2 s θs(1+es) (12) were θs is the granular temperature, es is the coe�cient of restitution for particle collisions. the radial distribution function, go, is de�ned by: go = [ 1− ( εs εs,max ) 1 3 ]−1 (13) solids shear stress. the solids stress tensor contains bulk and shear viscosities. the solid phase bulk viscosity are expressed as: µb = 4 3 εs ρsdsgo(1+ es)( θs π ) 1 2 (14) the solids phase shear viscosity is given by: µb = 2µs,dil (1+ e)go [ 1+ 4 5 (1+ es)goεs ]2 + 4 5 εs ρsdsgo(1+es)( θs π ) 1 2 (15) the solid phase dilute viscosity is: µs,dil = 5 16 ρsεsls √ 2πθs (16) where is, ls = √ 2 12 ds εs (17) the granular temperature, θs, is calculated by solving the turbulent kinetic energy equation for solid phase: 3 2 ∂ ∂t (ρsεsθs)+o(ρsεsusθs)=ts : ous+o(kθsoθs)−γs (18) the di�usion coe�cient for granular energy kθs is given by: kθs = 2kθs,dil (1+ es)go ( 1+ 6 5 (1+ es)goεs )2 +2ε2s ρsdsgo(1+es)( θs π ) 1 2 (19) where: kθs,dil = 75 64 ρsεsls √ 2πθs (20) the collisional energy dissipation, γs, is calculated by: γs = 3 ( 1− e2s ) ε2s ρsgoθs [ 4 ds ( θs π ) 1 2 −ous ] (21) generally, the mixer is below turbulent �ow conditions. therefore, it is crucial to apply the suitable turbulence model to illustrate the e�ect of turbulent �uctuations of velocities and scalar variables for the basic conservation equations. a k-� model was used to show the turbulent motions in both phases. in the k-� model, the turbulent viscosity is given by: µt,i(t)= ρiεicµ k2i �i (22) the turbulence kinetic energy, k, and its rate of dissipation, � , can be determined from the transport equations: ∂ ∂t (ρiεiki)+o(ρiεikiui)= o ( εi µt σk oki ) +(εigk−εi ρi�i) (23) ∂ ∂t (ρiεi�i)+o(ρiεi�iui)= o ( εi µt σk o�i ) + εi k (c1� εigk−c2� εi ρi�i) (24) 2.2.5 numerical procedure the geometry of pretreatment reactor is shown in figure 1. the numerical calculation used a two-dimensional mesh. the reactor had a diameter of 0.086 m and the height of 0.086 m. to decrease the computational e�ort, and due to the reactor is symmetric, the reactor was split to become a half part. initially, the acid-dilute pretreated samples settled at the reactor bottom to a level above the impeller, then sulfuric acid was injected to the rest of the reactor. the volume fraction of rice husk pretreated in the slurry entered to the reactor of 56 %, with © 2019 the authors. page 20 of 23 novia et. al. science and technology indonesia, 4 (2019) 18-23 figure 1. two-dimensional geometry of pretreatment reactor the average diameter of 60 µm. the operating conditions of reactor were the temperature of 85°c and the pressure of 1 atm. a schematic of the reactor and the initial position of slurry solution are shown in figure 1. within the domain, there are three �uid zones, representing the impeller zone (green colours), the region where the slurry is initially located (blue colours) and the rest of tank where naoh solution is �lled (grey colours). the simulations were started using the initial assumptions similar to the speci�ed volume fractions. the pretretreatment process was simulated for 60 min. a constant time step of 0.01 was used. the simpli�cation assumption is pretreated rice husk entered the reactor in the form of a slurry. 3. results and discussion 3.1 morphological of the rice husk structure figure 2 shows the morphology of the rice husk structure (before pretreatment), b (after alkaline pretreatment), c (after alkaline-acid pretreatment). major morphological changes of the rice husk (�g 2a) converted to �brous clusters (�g 2b) were detected. it was shown by sem that alterations in microstructure occurred. this is due to some lignin being eliminated by alkaline pretreatment. lignin was also removed signi�cantly during the alkaline-acid pretreatment (�g 2c). thus the pretreatment of rice husk made it much more porous to enzymes. cellulose and hemicellulose degradation occurred because of the reduction of lignin content and the alteration of its structural. 3.2 e�ect of the combination of alkaline and acid pretreatment on the rice husk composition 3.3 e�ect of single pretreatment on the lignin content of rice husk lignin is the main problem for the utilization of second generation bioethanol. the lignocellulose wall lets as an inhibitor reducing the accessibility of cellulose to be hydrolysed. the lignin content must be reduced as much as possible to provide a high e�ciency of pretreatment. as shown in fig 3, initially, figure 2. morphology of the rice husk structure before pretreatment (a), after alkaline pretreatment (b), after alkaline-acid pretreatment (c) the lignin content of rice husk was about 21.17%. after acid pretreatment, the lowest lignin content was 10.74%. alkaline pretreatment produced the lowest lignin content of 4.35%. fig 3 also illustrated that the higher concentration of either h2so4 or naoh caused the increasing of lignin degradation. the highest capability of lignin degradation by acid pretreatment was about 38.38 %. meanwhile, the alkaline pretreatment reduced the highest lignin content was about 55.34%. it can be concluded that h2so4 gave minor e�ect on lignin degradation level. on the other hand, naoh lead the major e�ect on the degradation of lignin. alkaline pretreatment broke down the lignin and glycoside bond on polysaccharide, so it can decrease the crystallinity. previous researcher studied the lowest of lignin content is about 3.46 % for solids pretreated at the acid concentration of 2% and 90 minutes of pretreatment time. the lowest performance of alkaline pretreatment on a hws (hot water solubility) of about 7.34% can be enhanced to become 9.71% by using combination alkaline-acid. hws content was about 10.39%. hws content for both pretreatment was higher than acid pretreatment. this is due to h2so4 formed emulsion at acid pretreatment. meanwhile at the combination pretreatment, before h2so4 form more emulsions, naoh bonded with h2so4 each other to become naso4 which is soluble in hot water. fig 4 shows the both pretreatment combination degraded hemicellulose of about 9.59% (alkalineacid) and 9.27% (acid-alkaline). the highest cellulose content was about 66.75 % for acid-alkaline pretreatment. for pretreatment combination, the lowest content of lignin was about 6.09% for acid-alkaline pretreatment. it can be concluded that combination of either alkaline-acid or acid-alkaline had similar capability in increasing hws, the © 2019 the authors. page 21 of 23 novia et. al. science and technology indonesia, 4 (2019) 18-23 figure 3. e�ect of the pretreatment on the lignin content of rice husk degradation of hemicellulose, the enhancing of cellulose and the degradation of lignin. the di�erence of both pretreatment was about ±1%. globally, acid-alkaline pretreatment was better than alkaline-acid pretreatment. 3.4 hydrodynamic analysis of pressure and volume fraction on acid-alkaline pretreatment using cfd (ansys fluent 16) to compare the simulation result and experimental data, this study focuses on hydrodunamics of acid-alkaline pretreatment. figure 5a shows the volume fraction of unpretreated rice husk. after pretreatment, the volume fraction of rice husk and reagent changed due to the mixing process. as illustrated in �g 5c and 5d, the impeller action caused the reagent in lower concentration (the blue color) and mixed with rice husk (red one). furthermore, the rice husk at the lower level �owed to the upper one and mixed with reagent in the perfect mixing. the volume fraction of rice husk reduced because of mixing between rice husk and reagent solution. figure 5b describes the distribution of pressure after pretreatment. the blue color represents hydrostatic pressure normally; the highest pressure is represented by red color. increasing of the pressure caused an enhancing of the higher kinetic energy turbulent which is desired in mixing of the rice husk and the reagent. we can see from the �gure the small amount of blue color above the impeller. this area had a minimum pressure of about -628 pa which is a vortex leading the minimum mixing e�ciency. the highest pressure was about 8570 pa (red color) where the maximal mixing occurred. figure 4. e�ect of di�erent pretreatment on the composition of rice husk 4. conclusions a sem-edx investigation recorded that alterations in microstructure were observed, since a huge fraction of lignin was reduced by alkaline pretreatment. more lignin was also removed in the combined alkaline-acid pretreatment. after acid pretreatment, the lowest lignin content was 10.74%. alkaline pretreatment produced the lowest lignin content of 4.35%. the highest capability of lignin degradation by acid pretreatment was about 38.38 %. meanwhile, alkaline pretreatment reduced the highest lignin content to about 55.34%. the lower performance of alkaline pretreatment on hws (hot water solubility) of about 7.34% can be enhanced to 9.71% using combined alkaline-acid. both pretreatment combinations degraded hemicellulose of about 9.59% (alkaline-acid) and 9.27% (acid-alkaline). the highest cellulose content was about 66.75 % for acid-alkaline pretreatment. the lowest content of lignin was about 6.09% for acid-alkaline pretreatment. it can be concluded that either the alkaline-acid or the acidalkaline combination had similar capability in increasing hws, the degradation of hemicellulose, the enhancing of cellulose and the degradation of lignin. the mixing area had the minimum pressure of about -628 pa which is vortex leading the minimum mixing e�ciency. the highest pressure was about 8570 pa (red color) where the maximal mixing occurred. the rice husk �owed upward to the upper level and mixed with reagent in the perfect mixing. © 2019 the authors. page 22 of 23 novia et. al. science and technology indonesia, 4 (2019) 18-23 figure 5. initial volume fraction of rice husk (a); contour pressure (b); volume fraction of rice husk after pretreatment (c); volume fraction of naoh after pretreatment (d) 5. acknowledgement the authors would like to acknowledge supports from universitas sriwijaya for funding the research project (unggulan kompetitif unsri, no. 1012/un9.3.1/pp2017). references cara, c. e. a. 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(2016). temperature distribution of biodiesel blends combustion in boiler using cfd-fluent. international journal on advanced science, engineering and information technology, 6(1) fang, h., c. zhao, and x.-y. song (2010). optimization of enzymatic hydrolysis of steam-exploded corn stover by two approaches: response surface methodology or using cellulase from mixed cultures of trichoderma reesei rutc30 and aspergillus niger nl02. bioresourcetechnology, 101(11); 4111–4119 hamelinck, c. n., g. van hooijdonk, and a. p. faaij (2005). ethanol from lignocellulosic biomass: techno-economic performance in short-, middleand long-term. biomass and bioenergy, 28(4); 384–410 harun, r., w. jason, t. cherrington, and m. k. danquah (2011). exploring alkaline pre-treatment of microalgal biomass for bioethanol production. applied energy, 88(10); 3464–3467 hermansyah, novia, m. sugiyama, and s. harashima (2015). candida tropicalis isolated from tuak, a north sumateraindonesian traditional beverage, for bioethanol production. microbiology and biotechnology letters, 43(3); 241–248 kaparaju, p. and c. felby (2010). characterization of lignin during oxidative and hydrothermal pre-treatment processes of wheat straw and corn stover. bioresource technology, 101(9); 3175–3181 karimi, k., g. emtiazi, and m. j. taherzadeh (2006). ethanol production from dilute-acid pretreated rice straw by simultaneous sacchari�cation and fermentation with mucor indicus, rhizopus oryzae, and saccharomyces cerevisiae. enzyme and microbial technology, 40(1); 138–144 kumar, s., u. kothari, l. kong, y. lee, and r. b. gupta (2011). hydrothermal pretreatment of switchgrass and corn stover for production of ethanol and carbon microspheres. biomass and bioenergy, 35(2); 956–968 li, h., n.-j. kim, m. jiang, j. w. kang, and h. n. chang (2009). simultaneous sacchari�cation and fermentation of lignocellulosic residues pretreated with phosphoric acid–acetone for bioethanol production. bioresource technology, 100(13); 3245–3251 mcintosh, s. and t. vancov (2010). enhanced enzyme sacchari�cation of sorghum bicolor straw using dilute alkali pretreatment. bioresource technology, 101(17); 6718–6727 mosier, n. (2005). features of promising technologies for pretreatment of lignocellulosic biomass. bioresource technology, 96(6); 673–686 novia, v. pareek, and t. agustina (2017). bioethanol production from sodium hydroxide dilute sulfuric acid pretreatment of rice husk via simultaneous sacchari�cation and fermentation. in in matec web of conferences novia, n., s. ray, , and v. pareek (2007). three-dimensional hydrodynamics and reaction kinetics analysis in fcc riser reactors. chemical product and process modeling, 2(2); 4 ohgren, karin, r. bura, j. saddler, and g. zacchi (2007). e�ect of hemicellulose and lignin removal on enzymatic hydrolysis of steam pretreated corn stover.”. bioresource technology, 98(13); 2503–10 sudiyani, y., j. waluyo, e. triwahyuni, d. burhani, muryanto, p. primandaru, a. p. riandy, and n. sumardi (2017). optimization pretreatment condition of sweet sorghum bagasse for production of second generation bioethanol. in aip conference proceedings. author(s) taherzadeh, m. j, and k. karimi (2008). pretreatment of lignocellulosic wastes to improve ethanol and biogas production: a review. international journal of molecular sciences 9(9):, 9(9); 1621–51 thomsen, m. hedegaard, a. thygesen, and a. b. thomsen (2008). hydrothermal treatment of wheat straw at pilot plant scale using a three-step reactor system aiming at high hemicellulose recovery, high cellulose digestibility and low lignin hydrolysis. bioresource technology, 99(10); 4221–28 xavier, a. m. r. b, m. f. correia, s. r. pereira, and d. v. evtuguin (2010). second-generation bioethanol from eucalypt sulphite spent liquor. bioresource technology, 101(8); 2755–61 © 2019 the authors. page 23 of 23 introduction experimental section materials methods experimental method of dilute acid pretreatment experimental method of dilute acid-alkaline pretreatment experimental method of alkaline-dilute acid pretreatment modeling of dilute acid-alkaline pretreatment by using cfd numerical procedure results and discussion morphological of the rice husk structure effect of the combination of alkaline and acid pretreatment on the rice husk composition effect of single pretreatment on the lignin content of rice husk hydrodynamic analysis of pressure and volume fraction on acid-alkaline pretreatment using cfd (ansys fluent 16) conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper vertical chlorophyll-a concentration profiles observed on the western coast of northern sumatera during the 2017 northeast monsoon iskhaq iskandar1*, qurnia wulan sari2, aan johan wahyudi3, afdal3, wijaya mardiansyah1 1department of physics, faculty of mathematics and natural sciences, sriwijaya university, palembang 30662, indonesia 2department of marine science, faculty of fishery and marine science, padjadjaran university, west java 40600, indonesia 3research center for oceanography, indonesian isntitute of science, jakarta 14430, indonesia *corresponding author: iskhaq@mipa.unsri.ac.id abstract subsurface chlorophyll-a (chl-a) concentration variability on sumatera’s northwestern coast is part of the phytoplankton biomass thatsupportsandenrichestheregion’sfisheriessupplies. duringthe2017northeastmonsoonseasonfrom25th november25to11th december, the ekspedisi widya nusantara (e-win) collected data from 16 stations. the finding demonstrates a rise in subsurface chl-aconcentrationasyougetclosertothecoast. furthermore, thedeepchl-amaximum(dcm)isonlyfoundoffshore, withdepths between 30 to 50 m and chl-a concentrations of 0.07 to 0.25 mg.m−3. surface chl-a concentrations near the coast were found to be high, ranging from 0.2 to 0.25 mg.m−3. keywords deep chlorophyll-a maximum, e-win cruise, modis aqua, surface chlorophyll-a received: 20 september 2021, accepted: 11 december 2021 https://doi.org/10.26554/sti.2022.7.1.36-40 1. introduction located in the tropical indian ocean, the northern sumatera region is subject to the monsoon system. it has been known that the monsoon system can generate upwelling/downwelling process along the coast. monsoon systems are thought to play a signi�cant impact in ocean circulation in this area, according to previous research (sari et al., 2018). the change of ocean circulation as well as nutrient source could a�ect marine food chain and �sheries production. the concentration of chlorophyll-a (chl-a) has been proposed as the best proxy for phytoplankton biomass, making it valuable for the study of primary production (huot et al., 2007). it should be noted that this study was conducted for the subtropical water with warm temperature. the photosynthetic parameters and thus primary productivity depend on the environmental variables. the primary productivity response may di�er depending on the geography. surface chl-a, for example, accounts for around 51% of the entire variance in integrated primary output in the argentine seas (lutz et al., 2010; segura et al., 2013). the modis satellite data in northern sumatera were used to examine the geographical and temporal variations of the surface chl-a (sari et al., 2018). the results demonstrate that in northern sumatera during the peak of boreal fall (boreal summer), the surface chl-a is high (low). furthermore, the monsoon system and associated atmosphere-ocean interactions in the tropical paci�c, namely the el niño-southern oscillation (enso), and in the tropical indian ocean, namely the indian ocean dipole (iod), have a signi�cant impact on the abundance of surface chl-a (sari et al., 2018; siswanto et al., 2015). chl-a maximum is not usually found at the sea surface, but it can also be found deeper than the euphotic zone’s bottom. the chl-a maximum cannot be measured using satellite remote sensing in this circumstance. moreover, seasonal and annual variations of surface chl-a represent unique spatial patterns on a global scale, according to satellite ocean color studies. on regional scales, satellite ocean color studies indicated a strong annual cycle of surface chl-a in the southeastern tropical indian ocean and northern sumatera, resembling subtropical or temperate regions (susanto et al., 2006; siswanto et al., 2017; iskandar et al., 2009; amri et al., 2014; sari et al., 2018). in this paper, we used vertically observed chl-a concentration from the e-win cruise during early of the 2017 northeast monsoon season in the western coast of northern sumatera region. the goal of this research is to look at the vertical patterns of chl-a concentration along the cruise track in sumatera’s northern portion. the rest of the paper is laid out as follows. the study area, data, and techniques are all described in section https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.36-40&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.36-40 iskandar et. al. science and technology indonesia, 7 (2022) 36-40 2. in section 3, we describe and discuss the study’s primary �ndings. the study’s result is presented in the �nal part. 2. experimental section 2.1 materials the research area is located between 12°n 3°s and 90°e 102°e on the western coast of northern part of sumatera (figure 1). the e-win cruise was conducted from 25 november to 11 december 2017 using the rv. baruna jaya viii of the indonesian institute of sciences. the cruise started from the station e1 near sabang, aceh to the station e16 in the eastern simeuleu island (figure 1). the cruise tracks are indicated by red line, while the conductivity-temperature-depth (ctd) observation stations are indicated by yellow �lled-stars. figure 1. the transect of the e-win expedition during the northeast monsoon of 2017 is shown by the red line, and the ctd stations are indicated by the yellow filled-circle. 2.2 methods chl-a concentrations were sampled at 16 locations along northern sumatera’s western coast. with a rosette sampler from niskin bottles installed on a sea-bird electronics conductivitytemperature-depth (ctd) type sbe-911 plus, discrete seawater samples were taken from 6 �xed depths (5, 50, 75, 100, 150, and 300 m) at each station. measurements of nutrient concentrations (phosphate, nitrate, and silicate) were carried out using the hach spectrophotometer (suzuki et al., 1995). the �uorometric approach was used to measure phytoplankton chl-a concentrations, as recommended by u.s. environmental protection agency (1983). under a vacuum pump with a pressure less than 30 cmhg, 0.1-1.0 liter of water was �ltered using the whatman cnm porous �lter with a 0.45 m and 25 mm diameter. before being examined, the membrane �lters were stored in a cooler (with temperatures below 4°c) for roughly 20 hours after being wrapped in aluminum foil (u.s. environmental protection agency , 1983). after �ltration, the samples were extracted using a 90 percent acetone extraction solution (cochlan and hendorn, 2012; holm-hansen et al., 1965) and centrifuged for 30 minutes at 4,000 rpm to separate the �lter from the chl-a-containing solution (cochlan and hendorn, 2012; holm-hansen et al., 1965). the vertical pro�les of �uorescence are then obtained by reading the �uorescent liquid using the au-10 turner trilogy fluorometer. the concentration of phytoplankton chl-a is de�ned as, chl-a(`g/l) = ((y −b)/m)(v/v ) (1) where y is a �uorescence value, b is the y axis value that intersects the curve calibration, m is a slope of the regression line on the standard curve (calibration), v is a volume of the extract (after addition of acetone 90%) (ml), and v is the volume of �ltered sample (ml). using ctd dataset, the mixed layer depth (mld) was calculated as a depth where the density increases by 0.125 kg.m−3 from that of the reference point (10 m deep) zeng and wang (2017) as shown in table 1. table 1. calculated mixed layer depth using density criterion station mld (m) e017-01 31 e017-02 20 e017-03 21 e017-04 15 e017-05 20 e017-06 25 e017-07 14 e017-08 50 e017-09 25 e017-10 22 e017-11 31 e017-12 18 e017-13 23 e017-14 24 e017-15 12 e017-16 19 e017-17 31 the in situ data is also compared to the surface chl-a concentration remotely-sensed by the moderate resolution imaging spectroradiometer (modis) aboard the aqua satellite between 25th november and 18th december 2017. the nasa goddard distributed active archive center provided the satellite data, which had a horizontal resolution of 4 km (https://modi s.gsfc.nasa.gov/). 3. results and discussion 3.1 vetical pro�les of chlorphyll-a concentrations and fluorescences based on the distance of stations to the coast, the water characteristics of the western coast of northern sumatera can be clustered into two regions (figure 1), namely the o�shore and the coastal waters. the vertical pro�les of chl-a along the western coast of northern sumatera, along with the vertical pro�les © 2022 the authors. page 37 of 40 iskandar et. al. science and technology indonesia, 7 (2022) 36-40 of the observed �uorescene, were used to identify each observation station in the present study. the �uorescene can be employed as an indicator of chl-a concentration, according to the method proposed in early study (sauzède et al., 2015; zhao et al., 2019). the water characteristic with deep chl-a maximum (dcm) and high surface chl-a (hsc) pro�le data was used to characterize the chl-a visual analysis (lavigne et al., 2015). vertical chl-a pro�les are often described using the dcm and hsc forms (lavigne et al., 2015). they are characterized by the relative position of mld and are referred to as "strati�ed" and "mixed," respectively. the hsc standard shape was generated for pro�les with a continuous decrease in chl-a from surface to depth (approximately 100 m), such as those seen during phytoplankton blooms (chiswell, 2011). pro�les with relatively high values in the mixed layer and a �uoresence peak directly below the mld are represnted by the dcm form. table 1 shows that the mld in the study area was usually between 14 and 50 m. the deepest mld is at station e017-08, with a depth of 50 m, while the shallowest mld is at station e017-17, with a depth of 14 m. figure 2. vertical pro�les of (a, d) chl-a concentration, (b, e) fluorescence, and (c, f) turbidity. the classi�cation is based on avertical chl-a concentration pro�le, with the upper panel representing stations with high surface chl-a (hsc), and the lower panel representing the stations with deep chl-a maximum (dcm) figure 2 depicts chl-a concentration, �uorescence, and turbidity pro�les in northern sumatera waters from the surface to 300 m depth. figures 2a and 2d show that the observed pro�les of chl-a concentration are remarkably comparable to the pro�les of �uorescence (figures 2b and 2e). with the exception of station e017-05, where no chl-a was identi�ed in the surface water, the surface chl-a concentration in northern sumatera waters was about 0.051 to 0.21 mg.m−3 (figures 2a and 2d). this indicates that the northern sumatera waters are oligotrophic waters. the high and low concentration of chl-a is closely related to the supply of nutrients originating from the land through the rivers discharge into these areas. the surface chl-a concentration was found more at the stations located close to the land than that at the stations located toward the sea. the highest concentration of surface chl-a was found at station e017-13, which lies between the sumatera and simelue island with a value of 0.21 mg.m−3. in the east of simelue island, we found turbid waters caused by the presence of suspended particles and high levels of sludge which were carried from the land and rivers around the island. meanwhile, the lowest concentration of surface chl-a was observed at stations e01703 and e017-07. this is presumably because the location of those stations were heading towards the open sea resulting in little input of nutrients from the land which causes less surface chlorophyll content. it was con�rmed by figure 2 that the stations located near the coast are having high surface chl-a concentration, while those located o�shore tend to have deep chl-a maximum. moreover, the coastal water is also characterized by high turbid water (figure 2c). it is worth noting that the land gives a lot of input into the waters. as a result, waters near the land become fertile water which will ultimately be bene�cial for phytoplankton to carry out photosynthetic activity. previous study has suggested that river runo� signi�cantly a�ect the content of nutrients (phosphate, nitrate and silicate) in the ocean (zhang et al., 2020). in addition, it can inferred aslo from figures 2 that high chl-a concentrations are found at the stations located around the estuary (stations e017-11 and e017-17). the degree of acidity (ph) and nitrate play vital roles in the aquatic environment’s health. ph �uctuations have an impact on chemical processes and biological organisms in the water as well as the toxicity of a chemical compound in water. the ph of water has a signi�cant impact on its metabolic activities, for example, if the ph is too low, nitri�cation will cease (le et al., 2019). while nitrate is a key component of primary productivity, it is also consumed by phytoplankton and is required for photosynthesis (li et al., 2010). figure 3. same as figure 2 except for vertical pro�les of (a, d) phosphate, (b, e) nitrate, and (c, f) silicate. phosphate, nitrate, and silicate vertical pro�les are shown in © 2022 the authors. page 38 of 40 iskandar et. al. science and technology indonesia, 7 (2022) 36-40 figure 3. phosphate has a vertical pro�le that ranges from 0.01 mg.m−3 at the surface to 0.063 mg.m−3 at 300 m depth (figures 3a, d), while nitrate has a vertical pro�le that ranges from 0 near the surface to 0.49 mg.m−3 at 300 m depth (figures 3a, d) (figures 3b, e). silicate has a vertical pro�le ranging from 0.05 mg.m−3 near the surface to 0.57 mg.m−3 at 300 m underground (figures 3c, f). there was no discernible di�erence in the vertical pro�les of phosphate, nitrate, and silicate between the stations along the coast and those o�shore, according to our �ndings. 3.2 the weekly satellite surface chl-a distributions we showed the distribution of surface chl-a before, during, and after sampling in this study. due to cloud cover, satellite image quality was poor from 25th november to 2nd december 2017. the satellite measurement nicely recorded the surface chl-a concentration during the sample (december 3–10, 2017) and after the sampling (december 11–18, 2017) (figure 4). the concentration of surface chl-a near the coast (0.3 – 1 mg.m−3) is clearly higher than in the o�shore area (0.10 – 0.2 mg.m−3), which is consistent with our in-situ observation. figure 4. weekly composite of surface chl-a derived from modis during a) 25 november-03 december 2017, b) 03-10 december 2017 and, c) 10-18 december 2017. 4. conclusions based on in-situ observations obtained during the e-win cruise from 25th november to 11th december 2017, this study analyzed the vertical pro�le of chl-a concentration in northwestern sumatera. discrete seawater samples were taken at depths ranging from 5 to 300 m. note that while the hach spectrophotometer was used to assess nutrient concentrations (phosphate, nitrate, and silicate), the �uorometric technique was used to detect phytoplankton chl-a concentrations. the results reveal geographical di�erences in vertical chl-a concentrations, with high surface chl-a concentrations found near the shoreline and dcm detected o�shore. station e01713, located between sumatera and simelue island, had the highest surface chl-a concentration of 0.21 mg.m−3. the lowest surface chl-a concentrations, on the other hand, were found at open-sea stations e03 and e017-07. furthermore, the staellite pictures con�rmed that chl-a concentrations in the coastal zone range from 0.30 to 1 mg.m−3, which is higher than the 0.10 to 0.2 mg.m−3 seen o�shore. the vertical pro�les of phosphate, nitrate, and silicate showed no substantial regional variation. 5. acknowledgement the authors thank to the indonesian institutes of sciences (lipi) through ewin cruise 2017. this study is supported by the ministry of education, culture, research and technology, indonesia through the penelitian dasar unggulan perguruan tinggi (pdupt) 2021 (contract number: 150/e4.1/ak.04.p t/2021). the third author (ajw) is supported by the lipijsps joint research grant (jpjsbp120198201) entitled indian ocean variability and its impact on climate and ecosystems of the maritime continent (2019–2022). references amri, k., a. priatna, and s. suprapto (2014). oceanographic characteristics and abundance of phytoplankton in the waters of the sunda strait in the east monsoon. bawal widya riset perikanan tangkap, 6(1); 11–20 chiswell, s. m. (2011). annual cycles and spring blooms in phytoplankton: don’t abandon sverdrup completely. marine ecology progress series, 443; 39–50 cochlan, w. and j. hendorn (2012). water quality methods. tiburon: romberg tiburon center for environmental studies, san fransisco state university; 317. holm-hansen, o., c. j. lorenzen, r. w. holmes, and j. d. strickland (1965). fluorometric determination of chlorophyll. journal of marine science, 30(1); 3–15 huot, y., m. babin, f. bruyant, c. grob, m. twardowski, and h. claustre (2007). does chlorophyll a provide the best index of phytoplankton biomass for primary productivity studies biogeosciences discussions, 4(2); 707–745 iskandar, i., s. rao, and t. tozuka (2009). chlorophyll-a bloom along the southern coasts of java and sumatra during © 2022 the authors. page 39 of 40 iskandar et. al. science and technology indonesia, 7 (2022) 36-40 2006. international journal of remote sensing, 30(3); 663– 671 lavigne, h., f. d’ortenzio, m. ribera d’alcalà, h. claustre, r. sauzède, and m. gacic (2015). on the vertical distribution of the chlorophyll a concentration in the mediterranean sea: a basin-scale and seasonal approach. biogeosciences, 12(16); 5021–5039 le, t. t. h., j. fettig, and g. meon (2019). kinetics and simulation of nitri�cation at various ph values of a polluted river in the tropics. ecohydrology & hydrobiology, 19(1); 54–65 li, w. k., m. r. lewis, and w. g. harrison (2010). multiscalarity of the nutrient–chlorophyll relationship in coastal phytoplankton. estuaries and coasts, 33(2); 440–447 lutz, v. a., v. segura, a. i. dogliotti, d. a. gagliardini, a. a. bianchi, and c. f. balestrini (2010). primary production in the argentine sea during spring estimated by �eld and satellite models. journal of plankton research, 32(2); 181– 195 kumar, s. p, m. nuncio, j. narvekar, (2004). are eddies nature’s trigger to enhance biological productivity in the bay of bengal geophysical research letters, 31(7); 1-8 sari, q. w., p. a. utari, d. 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and x.-q. luo (2020). spatiotemporal dissolved silicate variation, sources, and behavior in the eutrophic zhanjiang bay, china. water, 12(12); 3586 zhao, c., j. maerz, r. hofmeister, r. röttgers, k. wirtz, r. riethmüller, and c. schrum (2019). characterizing the vertical distribution of chlorophyll a in the german bight. continental shelf research, 175; 127–146 © 2022 the authors. page 40 of 40 introduction experimental section materials methods results and discussion vetical profiles of chlorphyll-a concentrations and fluorescences the weekly satellite surface chl-a distributions conclusions acknowledgement research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 92-95 © 2017 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 10 september 2017; revised 26 september 2017; accepted 26 september 2017 http://doi.org/10.26554/sti.2017.2.4.92-95 hepatoprotective effect of ethanol extract of matoa leaves (pometia pinnata) against paracetamol-induced liver disease in rats yosua maranatha sihotang1*, eka windiasfira1, hendro david ginola barus1, herlina1, rennie puspa novita1. 1department of pharmacy, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail: yosuamaranatha59@gmail.com. abstract the hepatoprotective effects of matoa leaves were evaluated by paracetamol-induced injury in rat’s hepatocytes. the ethanolic extract of matoa leaves (eeml) at doses of 200, 300, 500 mg/kg, po and silymarin at dose of 100 mg/kg, po were given for seven days. silymarin was given as the reference drug. hepatoprotective effect was studied by measuring the level of ast, alt, alp and total protein in serum. in vivo, oral treatment with eeml at dose of 500 mg/kg significantly reduced ast, alt, alp in serum whereas total protein was not significantly reduce in each groups. these results indicate that the hepatoprotective action of eeml is likely related to its potent antioxidative activity. neutralizing reactive oxygen species enhancing the activity of original natural hepatic-antioxidant enzymes may be the main mechanisms of eeml against paracetamol-induced injury. keywords: matoa leaves (pometia pinnata), paracetamol, silymarin, hepatoprotection 1. introduction liver is the vital organ that has major roles in metabolism, detoxification and elimination of toxic substances and liver disease is still a major health problem (adewusi and afolayan, 2010). free radicals are the major risk factor which lead to liver disease (valko, et al., 2007). paracetamol is a safe and effective analgesic and antipyretic drug. however, an overdose can cause hepatotoxicity in experimental animals and humans. paracetamol hepatotoxicity is the most frequent cause of acute liver failure of any etiology in the western world (larson et al., 2005; larson, 2007). paracetamol toxicity is due to the formation of n-acetyl p-benzoquinone imine (napqi) when a part of it is metabolized by cytochrome p450. napqi is a reactive metabolite of paracetamol, detoxified by glutathione (gsh) resulting in extensive hepatic gsh depletion. an overdose of paracetamol causes increasing amount of napqi and reacts with protein sulfhydryl groups, causing the covalent adduction of cellular proteins and causes oxidative stress and glutathione (gsh) depletion (knight et al., 2001). synthetic drugs used in the treatment of liver diseases are inadequate and sometimes can have serious side effects (prakash, et al., 2008). so, we attempted to evaluate alternative medicines as hepatoprotector from medicinal plants. one of the most popular models to evaluate the hepatoprotective potential of natural products is paracetamol-induced liver injury (jaeschke, et al., 2013). matoa leaves (pometia pinnata) contains antioxidant. previous study by suedee et al, 2013 succeed to isolate epicatechin, kaempferol-3-o-rhamnoside, quercetin-3-o-rhamnoside, glycolipid, 1-o-palmitoyl-3-o-[a-galactopyranosyl(1→6)-β-galactopyranosyl]-sn-glycerol, steroid glycosides, stigmasterol-3-o-glucoside and triterpenoid saponin pentacyclic, 3-o-α-arabinofuranosyl-(1→3)-[α-rhamnopyranosyl(1→2)]-α-arabinopyranosyl hederagenin from matoa leaves extract. a potential of hepatoprotective property underlying matoa leaves may be attributed to the antioxidative constituents (akachi, et al., 2010). the bioactive compounds that are responsible for relieving oxidative stress are usually indistinctly ascribed to polyphenols and flavonoids compounds (li, et al., 2015). hence an attempt has been made to assess the hepatoprotective role of matoa leaves. 2. experimental section 2.1. chemicals paracetamol (acetaminophen), hepa-q® capsule (silymarin), and standard assay kits of aspartate transaminase (ast), alanine transaminase (alt), alkaline phosphatase (alp), bilirubin and total protein was obtained from health laboratory in palembang. all other reagents were analytical grade. 2.2. plant materials the matoa leaves were collected from indralaya, ogan ilir dissihotang et al. 2017 / science & technology indonesia 2 (4) 2017: 92-95 93 trict south sumatra, indonesia. the sample was determined in herbarium departement of biology, faculty of mathematics and natural science andalas university. sample was thoroughly washed with tap water, sorted while wet, cut dried at 50°c for 5 days, and grinded into powder (purwidyaningrum, et al., 2017). 2.3. preparation of extract sample was extracted by maceration with 96% ethanol . 1 kg of crude extract was maceration with 1.5 l of 96% ethanol for 3 days at room temperature on a shake. done triplicate. the filtrate was collected, and then evaporated using a rotary vacuum evaporator at 45°c under reduced pressure and speed of 40 rpm to give a viscous extract and then freeze dried to give a dried extract. the extract was called eeml (sihotang, et al., 2016). 2.4. phytochemical screening phytochemical screening was carried out by standard procedures, as described by harborne (1998) and bargah (2015). the color intensity or the precipitate formation was used as analytical responses to these tests. 2.5. test for alkaloids about 3 ml of extract was stirred with 3 ml of 1% hcl on steam bath. 1 ml of mixture was taken separately in two test tubes. few drops of dragendorff’s reagent were added in one tube and occurrence of orange red precipitated was taken as positive. two the second tube mayer’s reagent was added and appearance of buff colored precipitate was taken as positive test for presence of alkaloids. 2.6. test for flavonoids to 1 ml of extract, 1ml of 10% lead acetate solution was added. the formation of a yellow precipitate was taken as a positive test for presence of flavonoids. 2.7. test for tannins about 2 ml of the extract was stirred with 2ml of distilled water and few drops of ferric chloride (fecl3) solution were added. formation of green precipitate was indication of presence of tannins. 2.8. test for saponins about 5 ml of extract was shaken vigorously with 5 ml of distilled water in a test tube and warmed. the formation of stable foam was taken as an indication of the presence of saponins. 2.8. test for terpenoids about 2 ml of the organic extract was dissolved in 2ml of chcl3 and evaporated to dryness. 2 ml of conc. h2so4 was then added and heated for about 2 minutes. development of a grayish color indicates the presence of terpenoids. 2.9. test for steroids liebermann burchard test: development of a greenish color when 2 ml of the organic extract was dissolved in 2 ml of chloroform and treated with concentrated sulphuric acid and acetic acid indicates the presence of steroids. 2.10. experimental animals albino adult wister male rats (150–200 g) were used for this study. animals were divided into six groups (n = 6/group) as follows: group i: normal control rats received na cmc 1% b/v 5 ml/kg b.w. orally for 7 days. group ii: rats received paracetamol 3 g/ kg b.w orally for 2 days. group iii: rats received the standard drug silymarin 100 mg/kg b.w. orally for 7 days. group iv: rats received sample eeml 200 mg/kg b.w. orally for 7 days. group v: rats received sample eeml 300 mg/kg b.w. orally for 7 days. group vi: rats received sample eeml 500 mg/kg b.w. orally for 7 days. all the animals in the groups iii–vi were pre-treated with eeml from 1st day to 5th day with concurrent administration of paracetamol on 6th and 7th day. during the period of eeml, the rats were maintained under normal diet and water ad libitum. after 2 days of respective drug treatments, animals were anaesthetized using diethyl ether inhalation jar. blood was collected through retro-orbital plexus under mild ether anesthesia (prakash, et al., 2008). 2.11. determination of key liver biochemical markers liver biochemical markers such as alt, ast, alp, and total protein have been evaluated in the serum. blood was obtained from all animals by puncturing the retro-orbital plexus. blood samples were allowed to clot for 45 min at room temperature. serum was separated by centrifugation at 2.5 x g at 30°c for 15 min and assayed for ast, alt, alp, and total protein as shown in table 2. (rajasekaran and periyasamy, 2012; abirami, et al., 2015). 2.12. statistical analysis all data were expressed as mean±standard deviation. statistical analysis was performed using one-way analysis of variance followed by post hoc tukey. significant differences were set at values <0.05. 3. result and discussion the results of phytochemical screening of matoa leaves (pometia pinnata) is presented in table 1. the etanol extract of matoa leaves (pometia pinnata) contains flavonoids., saponins., tannins., and triterpenoid/ steroid. phenolic and flavonoid compounds of plant extracts are recognized as active substances responsible for the antioxidant activity due to their free radical scavenging effects (li yin, et al., 2014). the result of determination of key liver biochemical markers are shown in table 2. the effects of the oral treatment of eeml on the serum ast, alt, alp, and total protein levels of table 1.the result of phytochemical screening no screening simplex eeml 1 alkaloids 2 flavonoids + + 3 saponins + + 4 tannins + + 5 triterpenoid/ steroid + + sihotang et al. 2017 / science & technology indonesia 2 (4) 2017: 92-95 94 hepatic-damaged rats are shown in table 2. the serum ast, alt, and alp levels of the paracetamol group were elevated, whereas the total protein of this group were not reduced, thus indicating that liver cell damage was significantly induced. the enhancement of eeml doses significantly attenuated the paracetamol-induced elevation of the ast, alt, and alp levels. these data suggest that eeml reduced the paracetamol-induced hepatic damage. paracetamol (acetaminophen) is widely consumed as an antipyretic drug that is safe in therapeutic doses but can cause fatal hepatic damage in human and animal at higher toxic doses. bioactivation of paracetamol by hepatic cytochrome p-450 leads to formation of a highly reactive and toxic metabolite n-acetyl-p-benzoquinone imine (napqi). napqi is normally detoxified by conjugation with reduced glutathione (gsh) to form mercapturic acid which is excreted in urine (abirami,, et al., 2015). toxic overdose of paracetamol depletes hepatic gsh content so that free napqi binds covalently to cellular mitochondrial proteins and results in massive necrosis and apoptosis of hepatocytes (chen,, et al., 2009., bhattacharyya, et al., 2013). an obvious sign of hepatic injury is the leaking of cellular enzymes such as alt, ast and alp into plasma. alt is more specific to the liver, and it is a better parameter for analyzing hepatic injury. high levels of ast indicate the cellular leakage as well as loss of functional ability of cell membrane in liver. serum alp is also related with liver cell damage. high concentration of alp cause serious hepatic damage in paracetamol treated rats (darbar, et al., 2011). the mechanism of hepatoprotection by eeml is due to their antioxidant potential. this suggests that eedm can reduce ros that may lessen the oxidative damage to the hepatocytes and improve the activities of the liver antioxidant enzymes, thus protecting the liver from paracetamol induced damage (valko, et al., 2007). also, the possible mechanism could be by the stimulation of hepatic regeneration through an improved synthesis of protein or accelerated detoxification and excretion. (akachi, et al., 2010). 4. conclusion oral treatment with eeml at dose of 500 mg/kg significantly reduced ast, alt, alp in serum whereas total protein was not significantly reduce. these results indicate that the hepatoprotective action of eeml is likely related to its potent antioxidative activity. it can be concluded in our study that etanol extract of matoa leaves (pometia pinnata) may have a protective effect against paracetamol induced hepatotoxicity in rats. acknowledgement we thank sriwijaya university for support of this research through “saintek” 2017 with contract number 0568/un9/pp/2017. references abirami, a., nagarani, g., siddhuraju, p. (2015). hepatoprotective effect of leaf extracts from citrus hystrix and c. maxima against paracetamol induced liver injury in rats. food science and human wellness, 4, 35-41. adewusi, e.a., afolayan, a.j. 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(2003). role of lipid peroxidation as a mechanism of liver injury after acetaminophen overdose in mice. toxicol. sci, 76, 229–236. [pubmed: 12944590]. larson, a.m. (2007). acetaminophen hepatotoxicity. clin. liver dis, 11, 525–548. [pubmed: 17723918]. larson, a.m., polson, j., fontana, r.j., davern, t.j., lalani, e., hynan, l.s., reisch, j.s., schiodt, f.v., ostapowicz, g., shakil, a.o., lee, w.m. (2005). acetaminophen-induced acute liver failure: results of a united states multicenter, prospective study. hepatology, 42, 1364–1372. [pubmed: 16317692]. li, s., tan, h.y., wang, n., zhang, z.j., lao, l., wong, c.w., table 2. effects of eeml on liver biochemical parameters groups (n=5) treatments liver biochemical parameters alt ast alp protein total (u/l) (u/l) (u/l) (u/l) i normal control 70.44 ± 5.634* 88.96 ± 8.657* 121.53 ± 23.353* 7.10 ± 0.827 ii paracetamol (pct) 136.88 ± 20.234 167.66 ± 39.047 198.42 ± 16.257 7.38 ± 0.376 iii silymarin + pct 88.30 ± 11.264* 104.98 ± 7.661* 128.82 ± 13.223* 7.02 ± 0.626 iv eeml 200mg/kgbb + pct 118.72 ± 10.011 229.42 ± 9.263* 211.10 ± 50.104 7.22 ± 0.228 v eeml 300mg/kgbb + pct 111.16 ± 7.717* 203.26 ± 31.446 141.17 ± 45.637 7.6 ± 0.374 vi eeml 500mg/kgbb + pct 95.86 ± 3.519* 106.08 ± 5.506* 131.18 ± 27.379* 7.08 ± 0.178 values are expressed as mean ± s.d (n=5). normal group and experimental groups were compared with paracetamol group: *p<0.05. there were values were significantly different (p< 0.05). sihotang et al. 2017 / science & technology indonesia 2 (4) 2017: 92-95 95 and feng, y. (2015). the role of oxidative stress and antioxidants in liver diseases. int. j. mol. sci, 16, 26087–26124. doi:10.3390. prakash, t., fadadu, s.d., sharma, u.r., surendra, v., goli, d., stamina, p., and kotresha, d. (2008). hepatoprotective activity of leaves of rhododendron arboreum in ccl4 induced hepatotoxicity in rats. journal of medicinal plants research, 2(11), 315-320. purwidyaningrum, i., sukandar, e.y., and fidrianny, i. (2017). antihypertensive activity of extract and fractions of matoa (pometia pinnata j. r & g forts) leaves. asian j pharm clin res, 10(3), 323-328. rajasekaran, a., and periyasamy, m. (2012). hepatoprotective effect of ethanolic extract of trichosanthes lobataon paracetamol-induced liver toxicity in rats. chinese medicine, 12(7), 1-6. sihotang, y., silalahi, j., and anjelisa, p. (2016). cardioprotective effect of ethylacetate extract of zanthoxylum acanthopodium dc. against doxorubicin-induced cardiotoxicity in rats. international journal of pharmtech research, 9(4), 249-253. suedee a, tewtrakul s, panichayupakaranant p. (2013). antihiv-1 integrase compound from pometia pinnata leaves. pharm biol, 51 (10), 1256-1261. valko, m., leibfritz, d., moncol, j., cronin, m., mazur, m.,telser, j., et al. (2007). free radicals and antioxidants in normal physiological functions and human disease. int. j. biochem. cell biol, 39, 44–84. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper preparation and evaluation of antihypercholesterolemic activity of atorvastatin calcium-maleic acid co-amorphous solids yudi wicaksono1*, shofiatul izzah al amaliyah1, finas rahmayanti1, viddy agustian rosidi1, lina winarti1, dwi setyawan2 1drug modification research group, faculty of pharmacy, university of jember, jember, 68121, indonesia2faculty of pharmacy, airlangga university, surabaya, 60286, indonesia *corresponding author: yudi.farmasi@unej.ac.id abstractatorvastatin calcium is a statin drug used for antihypercholesterolemic. the oral bioavailability of atorvastatin calcium is relatively lowbecause it is poorly soluble in water. the low oral bioavailability of the drug causes a decrease in its therapeutic effectiveness. thisstudy aimed to increase the solubility of atorvastatin calcium through the formation of co-amorphous solids and evaluate its activityas antihypercholesterolemic. atorvastatin calcium was prepared into co-amorphous solids with a maleic acid coformer using the spraydrying method. solids characterization was carried out using powder x-ray diffraction (pxrd), differential scanning calorimetry(dsc), fourier transforms infra red (ftir), and scanning electronic microscopy (sem). the solubility test was carried out using theshaking method, while the evaluation of antihypercholesterolemic was carried out in vivo in experimental animals. the results of theanalysis of diffractograms, thermograms, ftir spectra, and micrograph images showed that the atorvastatin calcium-maleic acidsolids prepared by spray drying were a co-amorphous solid. the atorvastatin calcium-maleic acid co-amorphous solids had a greatersolubility in water (p<0.05) when compared to pure atorvastatin calcium. however, the in vivo antihypercholesterolemic activityresults in experimental animals showed that the cholesterol-lowering activity of the atorvastatin calcium-maleic acid co-amorphoussolids was not significantly different (p>0.05) with pure atorvastatin calcium. this phenomenon is thought to be because atorvastatincalcium from co-amorphous solids in solution is more present as a charged fraction, affecting the permeability and absorptionprocess. keywordsatorvastatin calcium, antihypercholesterolemic, co-amorphous solid, maleic acid received: 3 december 2021, accepted: 16 march 2022 https://doi.org/10.26554/sti.2022.7.2.202-207 1. introduction atorvastatin calcium is a statin drug that is clinically used to lower blood cholesterol levels (sharma and mehta, 2019). atorvastatin calcium inhibits 3-hydroxy-3-methyl-glutarylcoenzyme a (hmg-coa) reductase, an enzyme that plays an important role in the production of cholesterol in the body (shaker, 2018; prihapsara, 2020). atorvastatin calcium shows very high permeability, but its solubility in water is very low, so its oral bioavailability is only 12-14% (kwon et al., 2019; prihapsara, 2020). this can lead to a decrease in its therapeutic eectiveness (trivedi et al., 2020). therefore, the solubility of atorvastatin calcium needs to be improved in order to increase its bioavailability and therapeutic eectiveness. the formation of co-amorphous solids is one method that has been proven to be used to increase the solubility of poorly soluble drugs (renuka et al., 2017; wicaksono et al., 2021). co-amorphous solids are a multicomponent amorphous solid system formed from drug and coformer molecules with small molecular weights (chavan et al., 2016). co-amorphous solids can increase the solubility of poorly soluble drugs because their molecular arrangement in solids is in a high internal energy phase so that the dissolution barrierenergy is lower (karagianni et al., 2018). another advantage of co-amorphous solids is the increase in physical stability due to intermolecular interactions between the drug and coformers molecules that can prevent molecularmobilizationsothat therecrystallizationprocessdoes not occur (chavan et al., 2016). therefore, co-amorphous solids are very promising as a solid form of poorly soluble drugs. onemethodforpreparingco-amorphoussolids is thespray drying technique. spray drying is often used for the formation of co-amorphous solids because it is easy to carry out, and the process is fast. co-amorphous solids resulting from spray drying are spherical particles (karagianni et al., 2018; wicaksono https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.202-207&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.202-207 wicaksono et. al. science and technology indonesia, 7 (2022) 202-207 et al., 2021). the spray drying technique is able to regulate the size distribution and morphologyof the expected solid particles by controlling the composition of the feed solution and drying speed. an additional advantage of the spray drying technique is that it is continuous manufacturing and easily scaling up (shi et al., 2019). the spray drying method has been successful in preparing atorvastatin calcium co-amorphous solids with maleic acid coformers. the atorvastatin calcium-maleic acid co-amorphous solid results from the spray drying method showed higher solubility than pure atorvastatin calcium (wicaksono et al., 2021). however, evaluation of the antihypercholesterolemic activity of atorvastatin calcium co-amorphous solid has not been carried out until now. in fact, this information is needed for the formulationofco-amorphoussolids intopharmaceuticalpreparations. therefore, a study was conducted on the preparation of atorvastatin calcium-maleic acid co-amorphous solids by spraydrying technique and followed byevaluation of its activity as an antihypercholesterolemic. the feed solution in the spray drying process was prepared with methanol because it dissolves atorvastatin calcium and maleic acid very well. in addition, methanol is relatively easy to remove from solid products, so it is often used for the preparation of pharmaceutical solids (ainuroq et al., 2018; ashwini et al., 2021; labib and nasr, 2021). 2. experimental section 2.1 materials pharmaceutical grade atorvastatin calcium was obtained from pt dexa medica (palembang, indonesia), while maleic acid and cmc-na (synthetic grade) were purchased from merck kgaa (darmstadt, germany). analytical grade methanol was purchased from pt. smart lab (tangerang, indonesia). wistar rats (male, 3-4 months old, bodyweight 100-300 grams) for experimental animals were obtained from the faculty of dentistry, university of jember. the research protocol on experimental animals was approved by the ethics committee of the faculty of dentistry, university of jember (letter number: 1056/un25.8/kepk/dl/2020). 2.2 methods 2.2.1 preparation of atorvastatin calcium–maleic acid coamorphous solids the co-amorphous solid of atorvastatin calcium was formed by using maleic acid as the coformer with a molar ratio of 1:1. the solids were dissolved in methanol to obtain a solution with a concentration of 5% (w/v). the solution was then dried using a spray dryer (lab plant sd-basic spray dryer) with a feed speed of 5 ml/min and air pressure of 6 scales. the inlet and outlet temperatures of the spray dryer were set at 60 and 55°c, respectively. the results of the dry powder were collected for further testing (wicaksono et al., 2021). 2.2.2 characterization of atorvastatin calcium–maleic a cid co-amorphous solids pxrd characterization of the atorvastatin calcium-maleic acid co-amorphous solids was carried out using a philip xpert instrument with a cuk𝛼 radiation source (_ = 1.5402 a°) whose voltage and current were set at 40 kv and 30 ma. the analysis was performed at an angle of 2\ at 5-50° with a scanning speed of 10°/min. dsc characterization of co-amorphous solids was carried out using a thermo plus dsc 8230 instrument in a temperature range of 30-200°c. the dsc instrument was run at a heating rate of 10°c/min and a dry airow of 50 ml/min. ftir analysis of co-amorphous solids was performed with a bruker alpha spectrophotometer. the ftir scanning was carried out with a resolution of 4 cm−1 in the wavenumber range of 4,000-600 cm−1. sem characterization of co-amorphous solids was carried out using a hitachi tm3000 instrument equipped with a hitachi e-1045 ion sputter. the sem instrument was set at a voltage and current of 15 kv and 12 ma, respectively, while the observations were carried out at the appropriate magnication. 2.2.3 solubility test solubility test was carried out by shaking method with approximately 25 mg of powder put into a 100 ml erlenmeyer glass, and then 10 ml of distilled water was added. the erlenmeyer glass was shaken with an orbital shaker at 175 rpm for 8 hours at 25°c. the obtained ltrate was ltered using a 0.45 `m cellulose nitrate membrane, and the atorvastatin calcium content was determined by utilizing a uv-vis spectrophotometer. 2.2.4 preparation and treatment of experimental animals the experimental animals were placed in clean cages and acclimatized for a week. the animals were randomly divided into four groups (n=3), namely group i (normal), ii (negative control), iii (pure atorvastatin calcium), and iv (atorvastatin calcium-maleic acid). the total cholesterol level of the experimental animals was measured (day 0), and then for 14 day, they were given normal feed (group i) and feeding with highcholesterol feed (groups ii, iii, and iv). the high-cholesterol feed was made of quail egg yolk at a dose of 10 ml/kg bw and 0.1% propylthiouracil solution, and the administration was done using oral gavage. the total cholesterol level of the experimental animals was measured again (day 15), and then they were given treatment for seven day (group i = normal feed, group ii = 0.5% cmc-na, group ii = pure atorvastatin calcium 1.8 mg/kg bw, and group iv = atorvastatin calcium-maleic acid co-amorphous solids 1.8 mg/kg bw). at the end of the treatment (day 22), the total cholesterol level of the experimental animals was measured again (djamil et al., 2020; kurniawan and audita, 2021). 2.2.5 measurement of total cholesterol levels of experimental animals the tip of the animal’s tail was cut o, and 10 microns of blood were collected in a tube. blood was placed at 25°c for 10 min © 2022 the authors. page 203 of 207 wicaksono et. al. science and technology indonesia, 7 (2022) 202-207 and then centrifuged at 4,000 rpm for 15 min. blood serum (5 ml) was added with 500 mlof cholesterol reagent (cholesterol oxidase-peroxidaseaminoantipyrinephenol/chod-pap) and then incubated at 25°c for 5 minutes. serum samples and standardsolutionswere thenmeasuredforabsorptionwithbiolyzer 100tm at a wavelength of 546 nm, and total cholesterol levels were calculated. the percentage decrease in total cholesterol levels is calculated bythe equation (initial cholesterol levels-end cholesterol levels)/initial cholesterol levels x 100% (wahjuningsih et al., 2018). 2.2.6 data analysis the data obtained were statistically analyzed by testing for normality using the shapiro-wilk test. if the data were normally distributed (p>0.05), the analysis was carried out with a signicance test using one-way anova and post-hoc lsd. if the data were not normally distributed, the analysis was carried out by the kruskal-wallis nonparametric test. the data is considered to have a signicant dierence if the p-value <0.05. 3. results and discussion 3.1 results of atorvastatin calcium-maleic acid solids the feed solution of atorvastatin calcium-maleic acid for the spray drying process was prepared in a 1:1 molar ratio. the amounts of atorvastatin calcium and maleic acid used were 4.56 and 0.44 grams (total weight 5 grams), respectively, and were dissolved in 100 ml of methanol to obtain a solution with a total concentration of 5% (w/v). the powder yield obtained after the spray drying feed solution was 1.2 grams or about 24% (w/w) of the amount of initial solid material. 3.2 characteristics of atorvastatin calcium-maleic acid solids the diractogram of the pxrd characterization is exhibited in figure 1. pure atorvastatin calcium has diraction peaks with relatively low intensity (≤ 1,000 units) at 7.36 and 18.79°, while maleic acid has many diraction peaks with high intensity (2,000-10,000 units) at 27.9, 32.1, 37.9, and 38.1°. the diractograms indicated that the starting material of pure atorvastatincalciumisanamorphoussolid, whilemaleicacid iscrystalline solid (lemsi et al., 2017; lee et al., 2017). the pxrd diractogram of atorvastatin calcium–maleic acid did not show adiractionpeak, indicatingthat thesoliddidnothaveacertain pattern, so it was an amorphous solid. single-phase amorphous solid systems consisting of two or more small molecules are referred to as co-amorphous solids (chavan et al., 2016; karagianni et al., 2018; wairkar and gaud, 2019; wicaksono et al., 2021). the dsc thermogram of pure atorvastatin calcium, maleic acid, and atorvastatin calcium-maleic acid is shown in figure 2. the thermogram curve of pure atorvastatin calcium has shown no sharp endothermic peak but has shown a glass transition temperature (tg) at166.1°c.maleicacidhasadsccurvewith asharp endothermic peakat 142.4°c (δh = 269.71 j/g), where the sharp endothermic peak indicates the melting peak of a figure 1. pxrd difractogram of (a) pure atorvastatin calcium, (b) maleic acid, and (c) atorvastatin calcium-maleic acid co-amorphous solids figure 2. dsc thermogram of (a) pure atorvastatin calcium, (b) maleic acid, and (c) atorvastatin calcium-maleic acid co-amorphous solids material. from the results of this dsc test, it can be concluded that pure atorvastatin calcium is an amorphous solid because it has no melting point but has a glass transition temperature, while the maleic acid coformer is a crystalline solid because it has a melting temperature (lemsi et al., 2017; lee et al., 2017). the conclusion of the dsc test about the type of the two solids is in agreement with the conclusion of the pxrd test. onthedsctest, theatorvastatincalcium-maleicacidsolids showed a thermogram curve with a tg at 160.9°c. the results of the dsc test indicated that the atorvastatin calcium and maleic acid molecules in the atorvastatin calcium-maleic acid solidhadformedco-amorphoussolids, namelyasolid thatdoes not have the long-range order of molecular packing (chavan et al., 2016). co-amorphous solids have higher internal energy than crystalline solids, so when heated, they do not show a melting point. co-amorphous solids show the presence of a glass transition temperature (tg) which is generally located between the melting point or the glass transition temperature © 2022 the authors. page 204 of 207 wicaksono et. al. science and technology indonesia, 7 (2022) 202-207 (tg) of its constituent components (shi et al., 2019). the dsc test in this study reached the same conclusion as the pxrd test, namely that the atorvastatin calcium-maleic acid solid is a co-amorphous solid. figure 3. ftir spektra of (a) pure atorvastatin calcium, (b) maleic acid, and (c) atorvastatin calcium-maleic acid co-amorphous solids the ftir spectra of pure atorvastatin calcium, maleic acid, and atorvastatin calcium-maleic acid are shown in figure 3. pure atorvastatin calcium spectra have absorption peaks at 3369 cm−1 (n-h strain), 3053 cm−1 (-oh stretching), 1658 cm−1 (c=ostretching), and1229cm−1 (c-nstretching). maleic acid has ftir spectra showing absorption peaks at 3057 cm−1 (-oh stretching) and 1703 cm−1 (c=o carboxylic acid stretching) (samsodien et al., 2017; wicaksono et al., 2019; wicaksono et al., 2021). the ftir spectra of atorvastatin calciummaleic acid showed absorption peaks as the constituent materials with a shift in wavenumber compared to the starting material. the absorption peak of atorvastatin calcium at 3369 cm−1 and 1658 cm−1 shift to 3392 cm−1 and 1651 cm−1, respectively. similarly, at the absorption peak of maleic acid, shifts occur at 3057 cm−1 and 1703 cm−1 to 2967 cm−1 and 1711 cm−1. the shifts in the ftir spectra of atorvastatin calcium-maleic acid indicated intermolecular interactions between the molecules. therefore, it can be concluded that the atorvastatin calcium and maleic acid molecules in the atorvastatin calcium-maleic acid solid are not a physical mixture but have formed a co-amorphous solid phase (karagianni et al., 2018). sem micrographs of pure atorvastatin calcium, maleic acid, and atorvastatin calcium-maleic acid co-amorphous solids are shown in figure 4. particles of pure atorvastatin calcium have needle shapes of varying sizes, whereas particles of maleic acid have an irregular shape. the atorvastatin calcium-maleic acid co-amorphous solids have spherical particles with hollowlooking surfaces. sem observations have shown that the atorvastatin calcium-maleic acid co-amorphous solids have a dierent shapeandsurface topographywith its individualconstituent figure 4. sem images of (a) pure atorvastatin calcium (15 kv, x5000), (b) maleic acid (15 kv, x500), and (c) atorvastatin calcium-maleic acid co-amorphous solids (15 kv, x2000) components, indicating the formation of a new solid phase (karagianni et al., 2018; wairkar and gaud, 2019). based on the results of characterization using pxrd, dsc, ftir, and sem, it can be concluded that the atorvastatin calcium-maleic acid solids prepared by spray drying are a co-amorphous solid. 3.3 solubility pure atorvastatin calcium and atorvastatin calcium-maleic acid co-amorphous solids in the solubility test showed the solubility in distilled water was 236.96±15.64 and 293.26 ± 17.11 mg/l, respectively. the formation of co-amorphous solids of atorvastatin calcium and maleic acid increased the solubility of atorvastatin calcium signicantly (p<0.05) compared to the solubility of pure atorvastatin calcium. co-amorphous solids have high solubility because thermodynamically, the solid is in a high energy state, causing the dissolution barrier energy to be lower. co-amorphous solids do not require energy for crystal lattice rearrangement during the dissolution process (chavan et al., 2016; karagianni et al., 2018; wicaksono et al., 2021). 3.4 antihypercholesterolemic activity antihypercholesterolemic activity test of atorvastatin calciummaleic acid co-amorphous solid was carried out in vivo in experimental animals. assessment of antihypercholesterolemic activity was carried out based on a decrease in total cholesterol levels in the blood of experimental animals before and after sample treatment (kurniawan and audita, 2021). total cholesterol levels on day 15 (after induction) in groups i, ii, iii, and iv were 91.54 ± 12.38, 68.46 ± 15.61, 107.44 ± 2.61, and 92.57 ± 15.56 mg/dl (table 1). these results indicate that the induction treatment in experimental animals for 15 day showed a signicant increase in total cholesterol levels (p<0.05) in the pure calcium atorvastatin group, while in the othergroup, it did not show a signicant increase (p>0.05). © 2022 the authors. page 205 of 207 wicaksono et. al. science and technology indonesia, 7 (2022) 202-207 table 1. total cholesterol level of experimental animals (n = 3) groups total cholesterol level after (mg/dl) decrease (%)0 day 15 day 22 day i 80.51 ± 20.44 91.54 ± 12.38 72.93 ± 7.58 19.75 ± 9.14 ii 62.60 ± 13.50 68.46 ± 15.61 57.14 ± 21.27 18.55 ± 16.23 iii 81.51 ± 19.05 107.44 ± 2.61 63.33 ± 13.79* 40.83 ± 14.39 iv 83.05 ± 10.85 92.57 ± 15.56 68.46 ± 7.05* 25.36 ± 6.53 description: i = normal control, ii = negative control, iii = pure atorvastatin calcium, iv = atorvastatin calcium-maleic acid co-amorphous solids. *: sample treatment signicantly reduced total cholesterol levels (p<0.05) the total cholesterol levels of groups i, ii, iii, and iv after sample treatment (day 22) were 72.93 ± 7.58; 57.14 ± 21.27; 63.33 ± 13.79, and 68.46 ± 7.05 mg/dl, respectively. total cholesterol levels in groups i and ii did not show a signicant dierence (p>0.05), which indicated that the sample treatment procedure had no eect on total cholesterol levels in experimental animals. the treatment of samples in group iii and group iv showed a signicant reduction in total cholesterol levels (p<0.05) in experimental animals. this indicated that the treatment of samples containing atorvastatin calcium has a lowering eect on total cholesterol levels in experimental animals. atorvastatin calcium works as an antihypercholesterolemic through the mechanism of inhibition of 3-hydroxy-3-methylglutaryl-coenzyme a (hmg-coa) reductase so that the synthesis of cholesterol in liver cell membranes and extrahepatic tissues becomes lower (shaker, 2018; sharma and mehta, 2019). in this study, based on total cholesterol levels before (day 15) and after treatment (day 22), the percentage decrease in total cholesterol levels due to treatment can be determined. the percentage reduction in total cholesterol levels in groups iii and ivwere 40.83 ± 14.39 and 25.36 ± 6.53%, respectively. total cholesterol levels in group iii showed a greater percentage of total cholesterol reduction than group iv, but statistical analysis using the anova test showed that the percentage reduction in total cholesterol levels was not signicantly dierent (p>0.05). the results of the solubility test showed that the atorvastatin calcium-maleic acid co-amorphous solid had a higher solubility than pure calcium atorvastatin. however, the results of the antihypercholesterolemic activity test showed that there was no signicant dierence in the percentage reduction in total cholesterol levels in groups iii and iv (p>0.05). data on the in vitro solubility of drugs, especially for drugs that are dicult to dissolve in water, cannot fully correlate with activity in vivo (brake et al., 2017). the in vivo activity of a drug is also inuenced by physiological factors such as transit time and stability in the gastrointestinal tract (dressman and reppas, 2000). the permeability properties also aect the absorption process and in vivo activity of a drug. dissolved drug molecules that are charged generally have lower permeability so that their absorption and in vivo activity decrease (sugita et al., 2021). in this study, the increase in solubility of the atorvastatin calcium-maleic acid co-amorphous solid was not directly proportional to its cholesterol-lowering activity. this phenomenon is thought to be due to the dissolved atorvastatin calcium molecules from the atorvastatin calcium-maleic acid co-amorphous solid forming a charged fraction due to the presence of maleic acid molecules. the formation of the charged fraction causes a decrease in the permeability of atorvastatin calcium molecules so that it aects the absorption process and activity in lowering cholesterol levels (sugita et al., 2021). 4. conclusions the results showed that atorvastatin calcium with maleic acid coformer using spray drying method produced co-amorphous solids. the solubility of the atorvastatin calcium-maleic acid co-amorphous solid was signicantly increased (p<0.05) compared to the solubility of pure calcium atorvastatin. however, the antihypercholesterolemic activity in experimental animals was not directly proportional to the results of the solubility test. the total cholesterol level of the experimental animal group treated with atorvastatin calcium-maleic acid co-amorphous solids was not signicantly dierent (p>0.05) compared to the group treated with pure calcium atorvastatin. these results are thought to be because atorvastatin calcium from co-amorphous solids in solution forms a charged fraction that aects the permeability properties and absorption process. 5. acknowledgement the author would like to thank the rector of the university of jember for the nancial support through the idb research grant 2020 (rector’s decree number 11153/un25/lt/2020 and contract letter number 2595/un25.3.1/lt/2020). references ainuroq, a., r.mauludin, d.mudhakir, ands.n.soewandhi (2018). anovel desloratadine benzoic acid co-amorphous solid: preparation, characterization, and stability evaluation. pharmaceutics, 10(3); 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232–239 wairkar, s. and r. gaud (2019). development and characterization of microstructured, spray dried co-amorphous mixture of antidiabetic agents stabilized by silicate. aaps pharmscitech, 20(3); 1–10 wicaksono, y., v. a. rosidi, s. y. saragih, l. s. fauziah, and d. setyawan (2021). preparation of spray dried coamorphoussolids toimprovethesolubilityanddissolutionrate of atorvastatin calcium. jurnal teknologi, 83(2); 77–83 wicaksono, y., d. setyawan, and t. a. siswoyo (2019). preparation and characterization of a novel cocrystal of atorvastatin calcium with succinic acid coformer. indonesian journal of chemistry, 19(3); 660–667 © 2022 the authors. page 207 of 207 introduction experimental section materials methods preparation of atorvastatin calcium–maleic acid co-amorphous solids characterization of atorvastatin calcium–maleic a cid co-amorphous solids solubility test preparation and treatment of experimental animals measurement of total cholesterol levels of experimental animals data analysis results and discussion results of atorvastatin calcium-maleic acid solids characteristics of atorvastatin calcium-maleic acidsolids solubility antihypercholesterolemic activity conclusions acknowledgement research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 105 109 © 2017 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 2 september 2017; revised 22 september 2017; accepted 25 september 2017 http://doi.org/10.26554/sti.2017.2.4.105-109 bamboo distribution in musi rawas district south sumatera province elyani ami1, laila hanum2, zulkifli dahlan2* 1department of environmental management, graduate school sriwijaya university, jl. padang selasa, n0. 524, bukit besar, palembang, indonesia 2department of biology, faculty of mathematic and natural science, sriwijya university, jl. palembang-prabumulih, km. 32, ogan ilir, south sumatera *corespending autor email: zulkifli.dahlan@gmail.com abstract indonesia is estimated to have 157 species of bamboo which is more than 10% of the world’s bamboo species. almost 50% of bamboo growth in indonesia is endemic bamboo and more than 50% of bamboo species life in indonesia have been utilized by the society conventionally. further, the bamboo utilization is still having high potential to be developed by increasing the industrial development. this research aimed to investigate the diversity of the bamboo species in south sumatera, particularly in musi rawas district. the result showed that in musi rawas district of south sumatera province there are 10 species of bamboo located at 11 locations in protected forest area of 883.60 ha and production forest area of 177,976.26 ha. the large number of bamboo potentials viewed from various aspects and the many types of bamboo scattered in this district can be a supporting data in doing bamboo conservation efforts, especially in musi rawas district of south sumatra province. keyword: bamboo, distribution, mura, maps 1. introduction bamboo is one of non-timber forest products that grow in secondary forests, open forests, and even in primary forest. bamboo also one of indonesian economic plant that mainly growth in people garden and villages. this plant commonly utilized intensively by the society, both in the villages and in the city, for their daily necessary. however, it was not utilized optimally in order to increase the foreign exchange. indonesia estimated has 157 type of bamboo species and it is 10% of the world bamboo species. the type of bamboo in the world is estimated to consist of 1250-1350 species. among the types of bamboo grown in indonesia, 50% of them are endemic bamboo and more than 50% of them have been exploited by the society and are highly potential to be developed. bamboo has many functions in may field such as industry, agriculture, and food. for example, bambusa vulgaris var vulgaris has been widely used for furniture, chostick, and pulp (berlian and rahayu, 1995). in dietary field, the bamboo shoots from some species i.e. bambusa blumeana, bambusa vulgaris var.striata, bambusa vilgaris,dendrocalamus asper, gigantochloa hassakarliana, gigantochloa nigrociliata, schizostachyum brachycladum, schizostachyum lima, schizostachyum silicatum, schizostachyum zollingeri, have been utilized as vegetables (arinasa, 2004). in the health field, bamboo has widely utilized for medical purpose. in this case, the root of the bamboo from the gigantochloa apus species has been used for kidney stone disease, gastric pains, hypertension, liver, kidney disease. while it stem could be used to facilitate the labor process, treat wounds, and heatiness (sujarwo et al.2010). in the construction field, since ancient times, some types of bamboo species such as gigantochloa pseudoarundinacea dan gigantochloa robusta have been applied as construction material and building accessories (sulastiningsih dan santoso, 2012). ecologically, the bamboo root will be able to maintain the hydrological system as water and soil binder so it can be used as a plant of conservation (hartono, 2011). according to the forest service of south sumatra (2015), the potential for non-timber forest products in south sumatra is speeded in various location i.e. 7.953 tons in natural reserves, 24.179 tons in national park, 6 tons in natural park, 16.454 tons in protected forest, 8.597 tons in production forest, 40.159 tons in production forest, and 4.054 tons in conservation production forest. recently, the research concerning in bamboo distribution in south sumatra has been done by some researchers. wardana et al. (2008) has reviewed the distribution and potential of bamboo ecology in bukit-jambul protected forest gunung patah pagaralam province of south sumatra province. nuraetin et al. (2014) has carried out an inventory and identification of bamboo species in the pagar alam bamboo forest area of south sumatra province. in this work, the large number of bamboo potentials and distribution in south sumatera was studied by various aspects particularly bamboo species from musi rawas district. the result of this investigation is hoped could be fulfilled the lack of the bamami et al. 2017 / science & technology indonesia 2 (4) 2017: 105 109 106 boo distribution in south sumatera. so it can be a supporting data in bamboo conservation efforts, especially in south sumatra. due to the lack of comprehensive data on the distribution of bamboo, in south sumatra especially in musi rawas district (mura), with forest area of mura (hl: 883,60 ha; hp: 177,976,26 ha) 2. experimental section 2.1. materials and instrumentation some tools and instrument used in this study were stationery, gps (global positioning system), hygrometer thermometer, soil tester, digital camera, machete, newsprint, large plastic sack, plant scissors, cloth shears, transparent plastic bags (40 x 60 cm), raffia rope, anti-thorn gloves, cardboard, cull box, hekter, ruler. the materials used in this work were bamboo samples and alcohol 70%. 2.2. sampling method sample collection was done by purposive sampling method. bamboo sample was collected according to the literature study from forestry service in 2015. the data from forestry department informed that there are five districts with largest forest area in south sumatera i.e. ogan komering ilir (oki) district (forest: 96,505.57 ha; production forest: 643,838.45 ha), musi rawas district (protected forest: 883,60 ha; production forest: 177,976,26 ha), musi banyuasin district (protected forest: 16.300,99 ha; conservation forest: 56,039.12 ha; production forest: 400,545.99 ha), ogan komering ulu selatan (okus) district (protected fores: 127.966,39 ha; production forest: 17,844.57 ha), and lahat district (protected forest: 48.312,30 ha; hp: 28,546,74 ha). in this research, the sample was collected mainly from the protected forest of musi rawas district. 2.3. procedure 2.3.1.observation observation is an early activity where researchers walk with the leader of local society or local people who know about bamboo and its growth location. the local society encountered when the observation conducted, as well as some peoples who knew about existence of the bamboo have been chosen as the respondents for the experimental data source. 2.3.2. interview the interview with the local society has been carried out with the chosen respondent in the observation step. the interview was conducted based on the question that constructed in structured way. some aspect that included in the questionnaire are the local name of the bamboo, indonesian name, the species name of the bamboo, the growth place, the benefit and utilization of the bamboo by local society. the result of the interview was concluded and summarized and re-read to the responder to check and ensure the truth. here is some question that given to the responder during the interview. 1. what type of the bamboo that exist in their area? 2. what is the local name of bamboo that exist in their area? 3. what is the bamboo utilized for? 4. is the bamboo existed in their area intentionally planted or has 5. been existed long time ago? 6. are there any communities or local society that cultivate bamboo? 7. is there a bamboo production site? if any where it was? 2.3.3. samples collection samples collection have been done by exploration method. the sample that collected was the bamboo shoots, stems, leaves, and reed. each sample labeled with hanging label then spaying with the alcohol 70% and stored in closed plastic bag and the samples ready for the identification. 2.3.4. the assessment of the environmental factor in the research location the assessment of environmental factors in research location was conducted by recording some environmental factors including air temperature, air humidity, soil moisture, soil ph and altitude. 2.3.5. samples identification the obtained bamboo samples then identified based on the taxonomy books such as k.m wong (1995), dransfield & widjaja (1995), widjaja (2001) and bamboo journals. each sample is documented in the form of a photograph. 2.3.6. sample description the result of the sample analysis and identification toward the characteristics and properties then converted into a complete description of each bamboo type. each part of the bamboo sample collected were described including bamboo shoots, roots, stems, and leaves, general properties to special properties such as the stature of bamboo shoots, roots, stems, and leaves. 2.3.7. data analysis the bamboo data obtained through the exploration is grouped, then the data of distribution and morphology are analyzed presented descriptively and tabulated with description of each type and photograph. 3. results and discussion distribution of bamboo plants in the district of musi rawas, sukaraya village, suku tengah rakitan ulu district, was grown over protected forest area cogong hill. the following figure is a map of exploration results of bamboo plant distribution in musi rawas district. figure 1 shows bamboo spots on the map of the cogong hill figure 1. the maps of bamboo location in cogong hill musi rawas district figure 1. the maps of bamboo location in cogong hill musi rawas district ami et al. 2017 / science & technology indonesia 2 (4) 2017: 105 109 107 forest area, where each type of bamboo is represented by a single map location icon. the description of each bamboo distribution is presented in table 2. the complete result of the bamboo species identification in cogong hill musi rawas district tabulated in table 1. the result that summarized in the table 1 clearly described that the distribution of the bamboo in musi rawas district, particularly in sukaraya village, suku tengah rakitan ulu subdistrict was dominated by ten bamboo species i.e. dapuk bamboo (bamboo glaucescens (steud), ampel bamboo (bambusa vulgaris (steud) widjaja), seruas bamboo (bambusa multiplex (lour) raeusch), aur polos bamboo (bambusa vulgaris var vulgaris schrad. ex wendl), aur thorns bamboo (bambusa blumeana j.a. & j.h. schultes ), kijang bamboo (bambusa vulgaris var striata schrader ex wendland) mayan bamboo (gigantochloa robusta kurs), black bamboo (gigantochloa atroviolacea), and yellow bamboo (schizostachyum brachyladum (kurz) kurz). 4. conclusion distribution of bamboo in the district of musi rawas, sukaraya villages, suku tengah rakitan ulu subdistrict, was dominated by ten species of bamboo namely; bamboo dapuk (bamboo glaucescens (steud) widjaja ), bamboo ampel (bambusa vulgaris (steud) widjaja), bamboo seruas (bambusa multiplex (lour) raeusch), bamboo aur polos (bambusa vulgaris var vulgaris schrad. ex wendl), bamboo aur thorns (bambusa blumeana j.a. & j.h. schultes ), bamboo kijang (bambusa vulgaris var striata schrader ex wendland) bamboo mayan (gigantochloa robusta kurs), black bamboo (gigantochloa atroviolacea), and yellow bamboo (schizostachyum brachyladum (kurz) kurz)). the result was presented in the form of digital map-based (spatial data) technology information displayed in a dynamic geographic information system application so that bamboo location data, photos and other relevant information can be easily understood and utilized. geographic information system application table 1. bamboo plants and environmental factor results in musi rawas district bamboo name latitude environmental factor air temperature humidity ph air soil gigantochloa pseudoarundinace (steud) widjaja -3.155 26.0 91% 30 6 dabuk bamboo 102.903 26.5 bambusa glancescens (willd) sieb -3.156 26.0 91% 30 6102.904 26.5 bambusa vulgaris schard. ex j.c. wenld -3.156 26.0 91% 30 6 ampel bamboo 102.905 26.5 bambusa multiplex (lour) raense -3.154 26.0 91% 30 6 seruas bamboo 102.905 26.5 bambusa vulgaris var vulgaris schrad. ex wendl -3.150 26.0 91% 30 6 102.904 26.5 aur polos bamboo bambusa blumeana j.a. & j.h. schultes -3.150 26.0 91% 30 6 102.904 26.5 aur berduri bamboo bambusa vulgaris var striata schrader ex wendland -3.151 26.0 91% 30 6 kijang besar bamboo 102.899 26.5 bambusa vulgaris var striata schard. ex wendl. -3.150 30.2 31.6 65% 50 5,1 kijang kecil bamboo 102.903 gigantochloa robusta kurs -3.156 30.2 31.6 65% 30 6 mayan bamboo 102.903 gigantochloa atroviolacea widjaja -3.155 30.7 84% 40 5,5 black bamboo 102.906 30.7 bambusa vulgaris var striata -3.155 31.5 76% 40 6 yellow bamboo 102.906 32.2 ami et al. 2017 / science & technology indonesia 2 (4) 2017: 105 109 108 that became the end result of this research was developed with dynamic web-based codegiqnitier programming language with homepage administrator to process input, update and delete data. references arinasa, i. b. k., 2005. keanekaragaman dan pengunaan jenisjenis bambu di desa tigawasa, bali. upt balai konservasi tumtable 2. bamboo picture and 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one part of a hospital that provides initial treatment for patients who suffer from illness andinjury, which can threaten their survival. the importance of integrated care in the ed is one of the keys to successfully treatingpatients at an advanced level. this becomes complex because the ed works in a team consisting of various multi-disciplinarysciences and limited human resources, facilities, and infrastructure. in the city of palembang, 23 hospitals have emergency roomfacilities from 18 sub-districts, by using the topsis (technique for others reference by similarity to ideal solution) method tovary the distance (radius) the optimal location of the emergency department is obtained according to the number of hospitals thathave emergency room facilities, namely ilir timur i district, ilir barat i district, sukarami district, and plaju district. based on theformulation of the p-median model and the completion of the topsis method, the order of districts that have optimal locationsfrom 18 sub-districts that have emergency department facilities in the city of palembang is obtained. keywordsoptimal location, emergency department, p-median problem, topsis method, palembang received: 3 january 2022, accepted: 14 april 2022 https://doi.org/10.26554/sti.2022.7.2.251-256 1. introduction the optimal location problems deal with the nding of the optimal location of the facilities (guzmán et al., 2016), formed the set covering problem (scp) (doungpan, 2020; octarina et al., 2020; zhang and zhang, 2015). in practical situations, it deals with the set of public facilities such as hospitals (sitepu etal.,2019; mohriandhaghshenas,2021),wastebinallocation (puspita et al., 2019), gas stations, and so on (özceylan et al., 2017). some research focused on hospital or emergency unit (ahmadi et al., 2017; priyandari et al., 2011; sadatasl et al., 2016), explain that ed is an emergency place in which a person needs immediate help because if he does not get immediate help, it can threaten his life or save him permanently. in these circumstances, the role of the hospital is very important (chen and yu, 2016; memari et al., 2018). one of the these are hospital’s supporting facilities, namely the emergency room and the availability and the closest location to reduce the risk of death due to the distance of the hospital location that can be reached. most models of scp only deal with the ability to set optimal facility location if the only parameter known would be the distance between facilities and distance between facilities and population (sitepu et al., 2019). some approaches are available to solve scp using exact (sitepu et al., 2019; sitepu et al., 2018), or heuristics methods (yuliza et al., 2021; avrahami and israeli, 2013; octarina et al., 2020; puspita et al., 2019). based on research that has been done previously by sitepu et al. (2018) in optimizing the location of emergency installations at health facilities in palembang city, this study extends the research that has been done by designing models with a criterion of unknown radius (bashiri and fotuhi, 2009), that never described before in dealing with ed di palembang city of the facilities to be fullled by utilizing the topsis method (olugu et al., 2021; sürmeli et al., 2015; surya, 2018; zhang et al., 2020), compared previously described by (sitepu et al., 2019). the topsis method (sürmeli et al., 2015), has an advantage with the ability to nd the optimal alternative where the alternative is closest to the positive ideal solution and farthest from the negative ideal solution. topsis requires an assessment of the performance of each alternative ai on each of the normalized cj criteria. the topsis method is used to nd the min-max value of the radius (amaldi et al., 2013). then, the research is intended to seek the possible new parameter concerning the unknown radius of the population involved closest to the facilities that have never been discussed https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.251-256&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.251-256 sitepu et. al. science and technology indonesia, 7 (2022) 251-256 table 1. list of names of sub-districts and hospitals that have ed sub-districts ed facilities of hospital alang-alang lebar ernaldi bahar psychiatric hospital bukit kecil rsu dr. ak gani public hospital mata public hospital gandus ilir barat i bunda public hospital siti khodijah public hospital bunda noni mother and child hospital siloam sriwijaya public hospital ilir barat ii kertapati rsia kader bangsa mother and child hospital seberang ulu i palembang bari regional public hospital seberang ulu ii muhammadiyah public hospital ilir timur i rsia yk madira mother and child hospital rk charitas public hospital sriwijaya public hospital ilir timur ii trinanda mother and child hospital ilir timur iii kalidoni az-zahra mother and child hospital pusri public hospital kemuning muhammmad hoesin public hospital hermina public hospital plaju pertamina public hospital marissa mother and child hospital sako sematang borang karya asih charitas public hospital sukarami ar-rasyid public hospital myria public hospital jakabaring source : cbs in palembang, year 2019 before in any research dealing with scp of ed in palembang city. lastly, the contribution of the research is to extend the research which involves the new parameter of unknown radius to be considered in solving the optimal location of ed, so enable the population that are closest to the facilities to have direct access immediately. 2. experimental section 2.1 method in this research, the type of data is secondary data from google maps in august 2021, to nd the distance (in km) between hospitals in each sub-district (center of the sub-district) in the city of palembang which has emergency facilities. while the method used is a descriptive model with data collection method approach that is using the document study method. the steps taken in conducting the research are following: (1) describe the data used which is the distance between the center point of the district and the ed location. (2) measure the mileage from each request location to the facility location using the help of google maps. (3) dene the p-median variables and parameters. (4) dene variables and parameters for location set covering problem (lscp), maximal covering location problem (mclp), and p-median. (5) modeling using topsis method. (6) finding a solution from the covering-based model. (7) analyzing the results of the covering-based model. (8) interpret the results obtained. 3. results and discussion based on palembang city health oce in 2018, from 18 subdistricts, there are 23 hospitals that have ed facilities as in cbs (central bureau of statistics) website list. then, assumed that: x̃i = district name, ỹi = hospital name, h̃i = number of hospitals in each district. then it canbeseenfromtable1, thenotationsofeachsubdistrict are for example, alang-alang lebar sub-district (x̃1), bukit kecil sub-district (x̃2), and so on until jakabaring subdistrict (x̃18). then, the notations continue for rsk ernaldi bahar (ỹ1), rsu dr. ak gani (ỹ2), and so on until rsk myria © 2022 the authors. page 252 of 256 sitepu et. al. science and technology indonesia, 7 (2022) 251-256 table 2. distance between request point i to alternative ed location j d ỹ1 ỹ2 ỹ3 ỹ4 ỹ5 ... ỹ23 x̃1 1.7 13 8.6 10 11 ... 8 x̃2 14 3 4.9 2.7 3.2 ... 7.6 x̃3 18 12 14 12 11 ... 17 x̃4 12 3.7 6.5 4.3 3.8 ... 7.2 x̃5 14 3.2 7.1 4.9 6.2 ... 8.3 x̃6 19 12 14 12 11 ... 15 x̃7 13 3.6 3.9 2.4 2.9 ... 5.4 x̃8 12 5.6 3.3 3.4 3.8 ... 4 x̃9 5.9 11 6.2 7.7 8.1 ... 9.7 x̃10 23 4.1 8.9 8 8.5 ... 10 x̃11 17 3.8 8.7 7.8 8.3 ... 13 x̃12 16 5.5 7.7 6.8 7.3 ... 9.1 x̃13 14 6.5 5.1 5.1 5.6 ... 5,4 x̃14 18 8.4 8.9 9 9.4 ... 12 x̃15 22 8.2 13 12 13 ... 14 x̃16 16 9.7 8.3 8.3 8.8 ... 9 x̃17 19 11 10 10 11 ... 18 x̃18 25 8.9 14 13 13 ... 15 source : google maps, taken in august 2021 table 3. determination the notation for alternatives and the weight of the criterion alternative weight h̃1 1 h̃2 2 h̃3 0 h̃4 4 h̃5 0 h̃6 1 h̃7 1 h̃8 1 h̃9 3 h̃10 1 h̃11 0 h̃12 2 h̃13 2 h̃14 2 h̃15 0 h̃16 1 h̃17 2 h̃18 0 (ỹ23). furthermore, for the number of hospitals in each subdistrict will be dened as (h̃i), for example, alang-alang lebar sub-district has 1 hospital (h̃1), bukit kecil sub-district has 2 hospitals (h̃2), and so on until the jakabaring sub-district has 0 hospitals (h̃18) as stated in table 1. table 2 displays the distance between the request point and ed location with a distance unit of kilometers (km), it can be seen in the distance between alang-alang lebar (x̃1) to rsk ernaldi bahar (ỹ1) is 1.7 km, and so on until jakabaring (x̃18), (myria hospital) (ỹ23) is 15 km. to reduce the average distance between the point of request and the point of ed location, the p-median problem model is used, namely: zp-median = max 18∑︁ i=1 32∑︁ j=1 h̃id̃i jx̃i j (1) subject to x̃1,1 + x̃1,2 + x̃1,3 + x̃1,4 + x̃1,5 + · · · + x̃18,23 = 1 (2) ỹ1 + ỹ2 + · · · + ỹ23 = 4 (3) x̃i1 + x̃i2 + x̃i3 + · · · + x̃i21 + x̃i22 + x̃i23 ≤ ỹj (4) based on the p-median model in determining the optimal location of the emergency department with the highest number of emergency installations completed in 4 districts. furthermore, to nd the optimal location of the hospital by using a radius to minimize the total allocation cost that does not depend on the distance between the points, namely: min max 18∑︁ i=1 32∑︁ j=1 h̃id̃i jx̃i j (5) so: min ©­«max ©­« m∑︁ i=1 n∑︁ j=1 (x̃1,1 + x̃1,2 + x̃1,3 + ... + x̃2,1 + x̃2,2 + x̃2,3 + ... + x̃23)d̃i j ª®¬ ª®¬ (6) using the min-max approach to assign service points so that each customer should not travel too far to the service point under consideration to nd the value of min-max using the topsis method. the optimal alternative solution in the topsis method will be the one that is closest to the positive ideal solutionandfarthestawayfromthenegative ideal solution. topsis requires a performance rating of each alternative ai on each normalized cj criterion, the steps of the topsis method: a. determine alternatives and criteria and their weights, where alternatives (x̃i) sub-district, namely alang-alang lebar subdistrict (x1), bukit kecil sub-district (x̃2), and so on until jakabaring sub-district (x̃18). for weight namely the number of each hospital in each sub-district, and for criterion (c) © 2022 the authors. page 253 of 256 sitepu et. al. science and technology indonesia, 7 (2022) 251-256 table 4. determination the normalized decision matrix d c̃1 c̃2 c̃3 ... c̃23 x̃1 0.101025071 0.376677119 0.222016265 ... 0.168778249 x̃2 0.199204365 0.086925489 0.12649764 ... 0.160339337 x̃3 0.256119898 0.347701956 0.361421827 ... 0.35865378 x̃4 0.170746598 0.107208103 0.167802991 ... 0.151900424 x̃5 0.199204365 0.092720522 0.183292498 ... 0.175107434 x̃6 0.270348781 0.347701956 0.361421827 ... 0.175107434 x̃7 0.184975482 0.104310587 0.100681795 ... 0.316459218 ... ... ... ... ... ... x̃8 0.35572208 0.257878951 0.100681795 ... 0.316459218 table 5. weighted normalized matrix d c̃1 c̃2 c̃3 ... c̃23 x̃1 0.101025071 0.376677119 0.222016265 ... 0.236403463 x̃2 0.39840873 0.173850978 0.252995279 ... 0.270175387 x̃3 0 0 0 ... 0 x̃4 0.682986392 0.428832412 0.671211965 ... 0.154385935 x̃5 0 0 0 ... 0 x̃6 0.184975482 0.347701956 0.361421827 ... 0.221929782 x̃7 0.170746598 0.104310587 0.100681795 ... 0.127850853 ... ... ... ... ... ... x̃8 0 0 0 ... 0 where c is the same as the hospital (yi = cj), as stated in table 2. b. create a normalized decision matrix, by doubling each distance (ỹ1)2 on (x̃1) then adding up to (ỹ1)2 on (x̃2) until (ỹ1)2 on (x̃18) then each entry distance (ỹ1) is divided by the result summation above. do the same for (ỹ23) to (x̃18) as explained in table 3. c. create a weighted normalized decision matrix, by multiplying each entry of the decision matrix is normalized with each weight as table 4 explained. d. determine the positive and negative ideal solution matrices, by grouping the values of the normalized decision matrix weighted in each column into two parts, namely positive (for the value of largest) and negative (for the smallest value) as table 5 explained. e. determine the distance between the value of each alternative and the ideal solution matrix positive and the ideal solution matrix is negative. for the positive in a way subtract each column of a positive matrix with entries in row (ỹ1) to (ỹ23), then rooted. while for negative subtract each row (ỹ1) to (ỹ23) to each entry in the negative matrix, as stated in table 6. f. calculates the preference value foreach alternative. with do x̃−1 x̃−1 + x̃ + 1 it up to x̃18. then sort from the most optimal to the least optimal value, so that the most optimal location is table 6. matrix of positive ideal solution and negative ideal solution criteria positive negative c̃1 0.682986392 0 c̃2 0.956390379 0 c̃3 0.671211965 0 c̃4 0.647086749 0 c̃5 0.657677381 0 c̃6 0.796052478 0 c̃7 0.706258955 0 c̃8 1.031308491 0 c̃9 1.206837006 0 c̃10 1.205411197 0 ... ... ... c̃23 0.75950212 0 obtained to the non-optimal location. then we get x̃9 as the most optimal location where (x̃9) ilir timur i district as stated in table 7. from table 8, it can be seen that the largest preference value is located in (x̃9), so (x̃9) as the most optimal location where (x̃9) ilir timur i sub-district, namely rsia yk madira, © 2022 the authors. page 254 of 256 sitepu et. al. science and technology indonesia, 7 (2022) 251-256 table 7. the dierence in values between each hospital option and the positive and negative ideal solution matrix d+ value d− value x̃1 2.953477 x̃1 1.550049 x̃2 3.207706 x̃2 1.364829 x̃3 4.381804 x̃3 0 x̃4 1.765836 x̃4 3.306415 x̃5 4.381804 x̃5 0 x̃6 3.028842 x̃6 1.515281 x̃7 3.892671 x̃7 0.557388 x̃8 3.763845 x̃8 0.667304 x̃9 0.761096 x̃9 4.229952 x̃10 3.686918 x̃10 0.902231 x̃11 4.381804 x̃11 0 x̃12 3.064979 x̃12 1.593795 x̃13 3.321605 x̃13 1.395468 x̃14 2.621008 x̃14 2.171972 x̃15 4.381804 x̃15 0 x̃16 3.386626 x̃16 1.116394 x̃17 1.824748 x̃17 3.008616 x̃18 4.381804 x̃18 0 table 8. preference and rank values for each alternative alternative preference rank x̃1 0.344186 6 x̃2 0.298484 8 x̃3 0 14 x̃4 0.651863 2 x̃5 0 16 x̃6 0.33346 7 x̃7 0.125254 13 x̃8 0.150594 12 x̃9 0.847508 1 x̃10 0.196601 11 x̃11 0 16 x̃12 0.342106 5 x̃13 0.295833 9 x̃14 0.453157 4 x̃15 0 17 x̃16 0.247921 10 x̃17 0.622468 3 x̃18 0 18 rsu rk charitas, and rsu srivijaya. figure 1 explains the locations of the facilities obtained. by applying the topsis method in determining the location of the hospital that has er facilities in the city of palembang, it is obtained that the location of the er in the subdistrict are listed as follows: ilir timur i, ilir barat i, sukarami, plaju, kalidoni, alang-alang lebar, kertapati, bukit kecil, kefigure 1. map of palembang and sub-districts source: palembang government, 2022 muning, sematang borang, ilir timur ii, sebrang ulu ii, sebrang ulu i, gandus, ilir barat ii, ilir timur iii, sako, and jakabaring sub-district. based on figure 1, there are 4 sub-districts have hospitals with the most optimal emergency facilities in the city of palembang, namely ilir timur i sub-district, ilir barat i subdistrict, sukarami sub-district, and plaju sub-district. 4. conclusion based on the research, the optimal location of the hospital that has emergency facilities in the city of palembang is located in the ilir timur i sub-district. the setting up of the location of the facilities enable population closest to the ed to reach the facilities as soon as possible. the reduction the risk of death that often occurs due to the distance from the location of hospitals that have emergency facilities can be achieved. forfurtherresearch, it is suggestedtoalso includesomenew parameters involved in designing the model of scp in ed in palembang to also include the possibility of recent conditions occurring in practical conditions. such as how to reach the facilities, the number of doctors involved in the hospital, or possibilities of transportation means existed. 5. acknowledgement on november23, 2020, dipaof the public service agencyof sriwijaya university 2021, sp dipa-023.17.2.677515 /2021, supported the publishing of this article. on april 28, 2021, the rector’s decree number: 0010/ un9/ sk.lp2m.pt/2021 was issued. references ahmadi, a., javid, p. seyedi, and s. s. syam (2017). a survey of healthcare facility location. computers & operations research, 79; 223–263 © 2022 the authors. page 255 of 256 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(2018). penilaian kinerja dosen menggunakan metode topsis (studi kasus: amik mitra gama). jurnal rekayasa sistem dan teknologi informasi, 2(1); 322–329 (in indonesia) yuliza, e., f. m. puspita, and s. s. supadi (2021). heuristic approach for robust counterpart open capacitated vehicle routing problem with time windows. science and technology indonesia, 6(2); 53–57 zhang, k. and s. zhang (2015). maximizing the service area: a criterion to choose optimal solution in the location of set covering problem. in 23rd international conference on geoinformatics, 1–3 zhang, l., j. zhan, and y. yao (2020). intuitionistic fuzzy topsis method based on cvpifrs models: an application to biomedical problems. information sciences, 517; 315–339 © 2022 the authors. page 256 of 256 introduction experimental section method results and discussion conclusion acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper znal-humic acid composite as adsorbent of cadmium(ii) from aqueous solution jeri rahmadan1, veronika parhusip2, neza rahayu palapa2,4, tarmizi taher3, risfidian mohadi2, aldes lesbani2,4* 1magister programme, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia2graduate school, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30662, indonesia3department of environmental engineering, faculty of mathematics and natural sciences, institut teknologi sumatera, lampung, 35365, indonesia4research center of inorganic materials and complexes, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30139, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstractthe modified znal composites with humic acid (ha/znal composite) were a coprecipitation method used as an adsorbent to removecadmium(ii) in an aqueous solution. the synthesized material was characterized using sem-edx, ftir, and xrd. from the analysisusing xrd, there is a widening peak at an angle of 2\ (24°), ftir analysis there is a new peak at 1000 cm−1 and 1220 cm−1 and semanalysis show that there is a change in surface morphology due to more aggregated particles. the experimental results on ha/znalcomposite followed the pso model, where the cadmium(ii) removal process was chemical adsorption. the adsorption isothermfollows the langmuir model where adsorption occurs in a monolayer and maximum adsorption capacity was obtained 38.76 mg/ghigher than pristine. thermodynamics of the adsorption process of cadmium(ii) in an aqueous solution occurred spontaneouslywhere g < 0 at all temperatures and endothermic properties were tested. the performance of the ha/znal composite showed thatstrong potential as an adsorbent of low cost, high efficiency, easy operation, and good reusability. the cadmium(ii) was absorbed onthe surface of ha/znal composite by surface complexation and chelating interactions, and surface complexation was the main routeof cadmium(ii) removal. in addition, ha/znal composite has excellent treatment efficiency in actual aqueous solution. keywordsldh, humic acid, composite, cadmium(ii), adsorption performance, regeneration received: 24 may 2021, accepted: 18 august 2021 https://doi.org/10.26554/sti.2021.6.4.247-255 1. introduction heavy metal accumulation is a threatening contaminant in waterpollutionbecauseof itshigh toxicity. oneofpollution isone of the most severe water pollution issues worldwide because of the high toxicity and easy accumulation of heavy metals. cadmium(ii) (cd(ii)) is one of the heavy metals that has received widespread attention today because of its high activity and is widely used in typical heavy metal elements (li et al., 2019). there are many ways to remove cd(ii) from aqueous solutions, including adsorption, ion exchange, chemical precipitation, membrane ltration, electrochemical treatment, plant and microbial methods (zhu et al., 2019). however, those methods have limitations. for example, chemical precipitation, such as chemical precipitation, is generally expensive and environmentally unfriendly because of the amounts of chemical reagents for regulating the ph (su et al., 2019). adsorption is popular because it has the advantages of easy operation, high eciency, and reusability (siregar et al., 2021). in addition, the adsorbent has a high potential for water treatment. activated carbon, zeolite, and silica gel are the adsorbents widely used in removing cd through the adsorption process. however, these materials have several disadvantages, are challenging to modify, and their structure tends to be rigid (gu et al., 2019). on the other hand, synthetic materials are easier to modify and exible. this uniqueness makes them interesting to study (yao et al., 2019). ldh is a material that can be easily modied (tichit et al., 2019). ldh is a synthetic anionic clay mineral having the general formula [m2+(1−x)m3+x(oh)2](an−)x/n•mh2o where m2+ and m3+ represent divalent metal cations and trivalent metal cations, respectively (bukhtiyarova, 2019). ldh is a stack of positive layers separated by interlamellar spaces consisting of anions and water molecules (mishra et al., 2018). whereas space within the anions has the role of counterbalancing and exchanging species symbolized by a−n, including nitrate, carbonate, sulfate, organic acid anions, and inorganic anions (sun et al., 2019). furthermore, ldh has a large surface area, good ion exchange capacity, layered structure, easy modication, high exibility, and acid-base properties (mostafa and bakr, 2019). however, ldh has several disadvantages, https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.247-255&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.247-255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 including peeling o during application and not reusing (ruan et al., 2016). so it is necessary to improve the structure of ldh in adsorbent applications by using supporting materials that can increase the layer integrity of ldh (qu et al., 2019). many researchers have modied ldhs as heavy metal adsorbents in aqueous environments and exhibited great adsorption performance. adsorbent fe3o4/mgal-ldh showed a large adsorption capacity as adsorbent of pb and cd metals in an aqueous solution (sun et al., 2019). lyu et al. (2019) reported that pb2+ and cd2+ adsorption using chitosan/mgal composite produced a maximum adsorption capacity of 33.3 mg/g and 140.8 mg/g in an aqueous solution. dye adsorption using cual/biochar composite, with a maximum capacity of 470.96 mg/g (palapa et al., 2020). humic acid (ha) is a natural and multifunctional macromolecular organic compound consisting of a carbon skeleton with a high aromatic character and having a functional group containing mostly oxygen atoms. the humic acid functional groups have dierent abilities as ligands in the formation of complexes with metal cations. extensive sources and low price of ha consider and has been considered as an adsorbent for heavy metals. recently, ha was included as a support material to increase the surface area of the material (shi et al., 2020). moreover, it has a large adsorption capacity and surface area (yang et al., 2019). advanced utilization of humic acid (ha) in a structural improvement of materials was reported in ldh composites. this material is used in removing water contaminants through the adsorption method. the materials that can be used for ldh modication are carbon-based, metal oxides, and synthetic polymer materials that can increase the integrity of the adsorbent to a certain extent and limit applications in wastewater treatment (zhanget al., 2020; normah et al., 2021). while other materials such as natural polymer materials have various sources, wide varieties, and low cost. therefore, the modied ldh material as a metal ion adsorbent has a much greater potential than other supporting materials. as promising adsorbent (basu et al., 2019). shi et al. (2020) wrote that humic acid/mg-al ldh composites as cd2+ metal adsorbent resulted in an adsorption capacity of 155.28 mg/g. znal-ldh was used as a raw material in this paper due to the ability of anionic species to intercalate and there is a large interlayer space (high porosity), the ability of anions to be exchanged between the positively charged layers, and the structural water resistance. however, znal-ldh has a weakness so that it needs to be modied to increase its integrity as an adsorbent (palapa et al., 2021). this paper will modify ldh by being composited with a carbon-based material, namely humic acid. this paper, synthesize ha/znal composite, was proposed and researched. considering the wide range of raw material sources and the sample preparation method, it may be a promising adsorbent with broad application prospects for cd(ii) adsorption. this research aimed to synthesize ha/znal composite explore its adsorption performance. first, i observed the surface properties of ha/znal composite with a series of characterization methods. then, the adsorption capacity of ha/znal composite was studied by batch cd(ii) adsorption experiments. in this paper, to see the performance of ha/znal composite adsorbent in absorbing metal cd(ii) in aqueous solution, it will be discussed and investigated in batch adsorption equipment, by covering various conditions such as the eect of ph, time, concentration, adsorption temperature, regeneration and eectiveness of the adsorbent so that it can be reused. 2. experimental section 2.1 material and instrumentation the synthesis of materials in this study used hcl (by merck), al(no3)3•9h2o (by merck) humic acid (by merck), naoh (by sigma aldrich), zn(no3)2•6h2o (by merck), cdcl2 (by merck), 1,10-phenanthroline monohydrate (by merck), acetate buer (by merck), ethanol (by merck), and acetone (by merck). in this paper, characterization material using xrd the rigaku miniex-6000 diractometer, the ftir analysis using shimadzu ftir prestige-21, and the sem analysis using sem quanta-650 oxford instrument. spectrophotometer uv-visible biobase bk-uv 1800pc was used to measure the concentration of the solution. 2.2 preparation of znal-ldh and ha/znal composite the preparation ha/znal composite was made by developing previous research using the coprecipitation method (shi et al., 2020). the preparation of znal-ldh was carried out by karami et al. (2019). the materials used in this synthesis included 10 ml of 0.75 m zn (no3)2.6h2o and 10 ml of 0.25 m al (no3)3•9h2o (3:1) mixed with vigorous stirring for one hour until homogeneous. then the resulting mixture was added with 1 g of humic acid and then stirred continuously until the solution was homogeneous. then the mixture was adjusted to ph 10 using a 2 m naoh solution slowly until a precipitate was formed in the solution. then the mixture was stored at 65°c for three days. finally, the composite was washed and dried at 40°c. 2.3 batch adsorption experiments and regeneration study in this paper, to determine the adsorption performance of znal-ldh and ha/znal composites various experiments need to be carried out. these included making a solution of 1.634 g cdcl2 with 1000 ml of water to obtain 1000 mg/l as a cd(ii) stock solution. standard solutions are prepared by diluting the cd(ii) stock solution. measurement of the standard curve was carried out by measuring each solution that had been complexed with a 1,10-phenanthroline solution and then measured using a uv-vis spectrophotometer at the maximum wavelength obtained. a batch system carried out the cd(ii) adsorption in aqueous solutions. the cd(ii) adsorption process was carried out by varying the ph of the initial solution from 2 to 9, contact time from 10 to 200 minutes, initial cd(ii) concentrations of 5 mg/l and 10 mg/l. the thermodynamic parameters are determined by concentration variation of (9, 12, 15, and 20) mg/l, 0.02 g of adsorbent, 20 © 2021 the authors. page 248 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 ml of cd(ii), and temperature variations at 30-60◦c. after that, the mixture was centrifuged at a constant stirring speed of 400 rpm then the mixture is ltered. the resulting supernatant was then measured to determine cd(ii) concentration using a uv-visible spectrophotometer after complexing with 1,10-phenanthroline. the process of regenerating uses the adsorption-desorption process repeatedly in 5 cycles. first, as much as 0.02 g of adsorbent was added 20 ml of cd(ii) with a concentration of 10 mg/l, stirred for 2 hours. the adsorbate residue was measured using a uv-vis spectrophotometer, and the adsorbent was dried for desorption using water, sodium hydroxide, hydrochloric acid, acetone, and ethanol. finally, a desorption process was carried out with several solvents to obtain a suitable solvent. in this paper, to determine the adsorption performance of znal-ldh and ha/znal composites various experiments need to be carried out. these included making a solution of 1.634 g cdcl2 with 1000 ml of water to obtain 1000 mg/l as a cd(ii) stock solution. standard solutions are prepared by diluting the cd(ii) stock solution. measurement of the standard curve was carried out by measuring each solution that had been complexed with a 1,10-phenanthroline solution and then measured using a uv-vis spectrophotometer at the maximum wavelength obtained. a batch system carried out the cd(ii) adsorption in aqueous solutions. the cd(ii) adsorption process was carried out by varying the ph of the initial solution from 2 to 9, contact time from 10 to 200 minutes, initial cd(ii) concentrations of 5 mg/l and 10 mg/l. the thermodynamic parameters are determined by concentration variation of (9, 12, 15, and 20) mg/l, 0.02 g of adsorbent, 20 ml of cd(ii), and temperature variations at 30-60◦c. after that, the mixture was centrifuged at a constant stirring speed of 400 rpm then the mixture is ltered. the resulting supernatant was then measured to determine cd(ii) concentration using a uv-visible spectrophotometer after complexing with 1,10-phenanthroline. the process of regenerating uses the adsorption-desorption process repeatedly in 5 cycles. first, as much as 0.02 g of adsorbent was added 20 ml of cd(ii) with a concentration of 10 mg/l, stirred for 2 hours. the adsorbate residue was measured using a uv-vis spectrophotometer, and the adsorbent was dried for desorption using water, sodium hydroxide, hydrochloric acid, acetone, and ethanol. finally, a desorption process was carried out with several solvents to obtain a suitable solvent. 3. results and discussion the structural morphologies of znal-ldh and ha/znal composite were investigated using sem with a particle size of about 10.00 mm, which had been successfully prepared (figure 1a and 1b) ha/znal composite figure had a rougher surface than znal-ldh, overall, and the composite presented a stacked layered structure with a large amount of debris, and this is due to the presence of humic acid. edx image (figure 1c and 1d) of ha/znal composite and the elemental mapping presented shows that the ha/znal composite contains zinc, aluminum, oxygen, carbon, and nitrogen of 13.3%, 6.6%, figure 1. morphologies and compositions of znal-ldh (a,c) and ha/znal composite (b,d) 46.9%, 24.6%, and 5.8% for znal-ldh pristine the content of zinc, aluminum, oxygen, and carbon were 48.3%, 38.2%, 4.9%, and 4.2% respectively. the mapping images show that oxygen, zing, and aluminum have an excellent correlation due to using the same raw material. the carbon distribution is heterogeneous, with more in the upper left and right sides and less in the middle. according to koesnarpadi et al. (2015) the eect of foreign carbon may cause this. nitrogen has a homogeneous distribution and good correlation with other elements, but the overall content was lower. the rough surface and debris may both create new adsorption sites, which increase the adsorption of cd(ii). figure 2. xrd patterns and ftir spectra of znal-ldh (a) humic acid (b) and ha/znal composite (c) the xrd and ftir characterization of znal-ldh, humic acid, and ha/znal composite was shown in figure 2. figure 2a znal-ldh pristine has diraction peaks at 10.29°, 20.07°, 29.59°, 32.12°, 34.02°, 48.06° and 60.16° that can be indexed to the (003), (006), (101), (012), (015), (107) and © 2021 the authors. page 249 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 (110) based on the diraction peaks the formation of the znal material structure is following jcpds 48-1023 le. figure 2b shows that the diraction peaks at 12.36° (001), 20.01° (110), 24.88° (002), and 26.64° (111) are typical peaks of humic acids. according to abate and masini (2005) the diraction peak at 20-26° indicates that the humic acid contains a lot of carbon and oxygen. figure 2c for ha/znal composite all the diraction peaks matched well with those of znal-ldh pristine, in figure 2c the diraction peak around 24° is the characteristic peak of the ha/znal composite material which has an amorphous diraction pattern (shi et al., 2020). this may be related to the addition of modied humic acid. the results of material analysis using ft-ir spectrum are shown in figure 2. the characteristic peaks of humic acid in the composite were detected around the peaks at 1000 cm−1 and 1220 cm−1 indicating c-o and -cooh groups. according to shi et al. (2019) the characteristics of humic acids are characterized by the presence of a carboxyl group (-cooh). the band at 3448.72 cm−1 indicated the o-h region extends from the material layer and water molecules between layers. the peak at 1703 cm−1 indicates a coo-carbonyl group, the peak at 1000 cm−1 indicated the c-c group. the characteristic band of the -oh group in the layer and peak of the h2o bending vibration is 1637.7 cm−1 (deng et al., 2015). the peak at 1500-1800 cm−1 indicates the coogroup. the peak at 2088.8 cm−1 is the c-o vibration (sun et al., 2019). the peak of 1250 cm−1 indicated the c-oh group. the peak at 1117.8 cm−1 corresponds to the –coo– vibration and the c–o strain vibration, respectively (shi et al., 2019). in addition, the bands at 671.3 cm−1 and 558.8 cm−1, located in the 450 cm−1 –750 cm−1 region, all represent al-o and zn-o vibrations. overall this conrms that humic acid has been successfully loaded into ldh. 3.1 eect of solution ph and eect of initial concentration the adsorption process in this paper controls the ph of the solution as the main parameter. because it can aect the surface charge of the adsorbent and the ionization behavior of the solution. the cd(ii) solution with a concentration of 5 mg/l for znal-ldh and 10 mg/l for ha/znal composite where the ph was adjusted with hcl (0.1n) and naoh (0.1n). in figure 3a cd(ii) removal increased signicantly with increasing ph of the initial solution, highest adsorption capacity at ph 6.5 for ldh pristine and ph 6 for composites the removal eciencies can reach up to 68.01% and 90.77% respectively. this may be due to the deprotonation of functional groups in the ha/znal composite through the formation of hydrogen bonds or water bridges, electrostatic interactions or ion exchange, coordination bonds, and chelate ring structures. at low ph, the adsorbed cd(ii) is very small, and a cd(ii)-ha/znal composite complex is formed. this is due to a large number of cd(ii) h+ ions in the system causing the composite to tend to be protonated, which results in strong hydrogen bonds between functional groups in protonated composites, both intermolecular (terdkiatburana et al., 2008). prevent the adsorption of metal ions on figure 3. ph amount of znal and ha/znal composite (a) initial cd(ii) concentration (b) the composite surface due to electrostatic repulsion between equal charges. in this paper, the initial concentration of metal ions plays an important role in adsorbent absorption. the eect of initial concentrations of cd(ii) (9, 12, 15, and 20 mg/l) was tested using znal-ldh and ha/znal composite at ph 6.5 and ph 6. figure 3b the resulting adsorption capacity increased at low concentrations. while the adsorption capacity gradually decreased with increasing cd(ii) concentration. this process indicates that thevacantactivesitesonbothadsorbentsarelled at critical concentrations. however, the equilibrium adsorption capacity continued to increase as the cd(ii) concentration increased. the maximum absorption of cd(ii) using znal pristine is 19.92 mg/g while ha/znal composite is 21.882 mg/g. 3.2 adsorption kinetics and isotherms the eect of adsorption time on cd(ii) adsorption in aqueous solution using znal-ldh and ha/znal composite was through variations in the contact time of the adsorbate with the adsorbent. a total of 0.02 g of the sample was added to an erlenmeyercontaining20 mlof cd(ii) with aconcentration of 5 mg/l for znal-ldh and 10 mg/l for ha/znal composite whose ph value had been adjusted according to the provisions, with time variation 10-200 minutes. the adsorption ability of all concentrations increased with increasing time from 0 to 120 minutes for the ha/znal composite occurred rapidly in the rst stage. while the second stage is slower and tends to equilibrium, this tendency in the early stages, this process occurs because the higher accessibility of the carboxyl group results in many vacant sites for adsorption on the surface of the adsorbent. the optimal equilibrium time was 120 minutes for znal-ldh and 90 minutes for ha/znal composite. adsorption kinetics of cd(ii) onto znal-ldh and ha/ znal composite was investigated using pseudo-rst-order and pseudo-second-order, shown in equations (1) and (2) log (qe-qt) = log qe– k1 2.303t (1) t qt = ( 1 k2qe2 ) + 1 qe t (2) © 2021 the authors. page 250 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 table 1. parameters kinetic for cd(ii) adsorption onto znal-ldh and ha/znal composite kinetics models parameters adsorbent znal-ldh ha/znal composite pfo qeexp (mg/g) 4.148 8.61 qecalc (mg/g) 4.797 7.509 k1 (min−1) 0.021 0.02 r2 0.928 0.979 pso qeexp (mg/g) 4.148 8.61 qecalc (mg/g) 5.359 10.267 k2 (min−1) 0.003 0.002 r2 0.99 0.994 figure 4. time adsorption of cd(ii) by znal-ldh and ha/znal composite where qe (mg/g) and qt (mg/g) are the adsorption capacity of znal-ldh and ha/znal composite for cd(ii) at equilibrium and time t (min), respectively; k1(1/min) and k2 (g/mg.min) are the rate constants of the pseudo-rst-order and pseudo-second-order models, respectively. the results of the two-parameter kinetic model are shown in table 1. both adsorbents provide a larger correlation coefcient (r2) in the pseudo-second-order model compared to the pseudo-rst-order model. from the results obtained, the pseudo second orderkinetics model is more suitable to describe the adsorption of cd(ii) on znal-ldh and ha/znal-ldh composite. according to niu et al. (2011) this proves that the rate-limiting step for znal-ldh and ha/znal composite adsorption of cd(ii) is most likely chemical adsorption. in addition, the resulting qe value for the ldh pristine adsorbent is smaller than the qe value for the composite adsorbent, the adsorption process can involve a series of functional groups on the surface of the composite, including hydroxyl groups, carboxyl groups, etc. these results indicate that composite material exhibits a large adsorbent potential compared to ldh pristine. the isotherm data analysis has shown that the isotherm parameters were calculated using the langmuir isotherm model, formulated in equations (3). the hypothesis of the langmuir figure 5. adsorption isotherm of cd(ii) by using znal-ldh (a) and ha/znal composite (b) adsorption model, the adsorbent has several properties, including uniform adsorption sites, monolayeradsorbent surface, and no lateral interactions between the adsorbed molecules. ce qe = ce qm + 1 qmkl (3) the equilibrium concentration of cd(ii) and equilibrium adsorption capacity of znal-ldh and ha/znal composite materials are respectively ce (mg/l) and qe (mg/g). the maximum adsorption of the langmuir model is qm (mg/g). langmuir’s constant is kl (l/mg). the isotherm ttings parameters are shown in figure 5 and table 2. the maximum adsorption capacity of the ha/znal composite increased signicantly up to 38.76 mg/g at 60°c. the maximum adsorption capacity of ha/znal composite is higher than ldh pristine. thus, the ha/znal composite showed high eectiveness in adsorption. this nding conrms that the composite material improves the absorption performance of heavy metals related to the synergistic eect of humic acid which contains many functional groups such as carboxyl and znal-ldh in the composite because of the surface area of the ha/znal composite is higher than ldh pristine. © 2021 the authors. page 251 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 table 2. parameters and coecient of langmuir isotherms models of cd(ii) adsorption onto znal-ldh and ha/znal composite adsorbent adsorption isotherm t (◦k) adsorption constant qmax kl r2(mg/g) (l/mg) znal-ldh langmuir 303 19.920 0.259 0.989 313 19.305 0.344 0.985 323 19.802 0.353 0.977 333 22.727 0.349 0.997 303 21.882 0.609 0.998 ha/znal 313 20.325 0.842 0.969 composite 323 21.834 0.929 0.964 333 38.760 0.408 1.000 table 3. thermodynamic parameters for the adsorption of cd(ii) onto znal-ldh and ha/znal composite t (◦k) concentration znal-ldh ha/znal composite (mg/l) δh(j/mol) δs (j/mol.k) δg (kj/mol) δh(j/mol) δs (j/mol.k) δg (kj/mol) 303 20 11.724 0.043 -1.377 29.329 0.105 -2.568 313 -1.81 -3.621 323 -2.242 -4.674 333 -2.675 -5.726 3.3 thermodynamic parameter adsorption calculation of thermodynamic parameters using the following van’t ho equation (4) and (5). the value of enthalpy (δh) and entropy (δs) can be calculated as the slope and intercept value of 1/t concerning ln qe/ce as shown in equation (4). ln qe ce = δs r − δh rt (4) figure 6. van’t ho linearity equation for the adsorption of cd(ii) onto znal-ldh (a) and ha/znal composite (b) the value of the gibbs free energy change (δg) is calculated from the enthalpy value (δh) and entropy (δs) is presented in equation (5). δg = δh −tδs (5) table 3 describes the adsorption process that occurs endothermically, where the adsorption process occurs followed by the capture of heat from the environment to the system, this is indicated by the enthalpy value (δh) which is positive. according to rakić et al. (2015) endothermic process, the adsorbate species displaces more than one water molecule to be adsorbed. the value of δh also describes the type of adsorption. the low enthalpy (δh) shows that cd(ii) is adsorbed through a physical interaction process (juleanti et al., 2021). δs positive value indicates an increase in randomness on the surface of the adsorbent with the solution during the adsorption process, this is because of the physical bond between the cd(ii) molecule and the active site of the znal-ldh and ha/znal composite decreases with increasing temperature. δg negative value indicates that the adsorption process occurs spontaneously by the znal-ldh and ha/znal composite. overall it can be concluded that the adsorption of cd(ii) is aected by changes in the temperature of the solution. 3.4 adsorbents performance the most important indicator to evaluating the performance of adsorbent is by carrying out the desorption and reusability process. the adsorbent desorption process was carried out using several eluents for cd(ii) desorption from the znal-ldh and ha/znal composite as shown in figure 7a. the results obtained that the percentage of desorption in acid solution was as high as possible according to the ldh charge to be positive. however, the electrostatic attraction of the cd(ii)-adsorbent molecules and h-bonds weakened. based on pearson’s clas© 2021 the authors. page 252 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 table 4. comparison of cd(ii) absorption using several types of adsorbents adsorbent experimental t/min adsorption capacity refcondition (mg/g) ha/mgal-ldh ph = 5.5 80 155.28 (shi et al., 2020) fe3o4/mg–al–co ph = 9.0 300 45.6–54.7 (shan et al., 2015) mg/alco3–ldh ph = 4.0 60 61.4–70.2 (shan et al., 2015) cqds/znal-ldh ph = 6.0 20 12.6 (rahman et al., 2018) femnmg-ldh ph = 6.5 250 59.99 (zhou et al., 2018) mgo/mgal-ldh ph = 6.5 240 45.05 (huang et al., 2018) kiwi biochar/mgfe-ldh ph = 6.5 120 25.8 (tan et al., 2019) humic acid (ha) ph = 5.0 60 8,8 (abate and masini, 2005) biochar w/ha ph = 7.5 30 167.3 (park et al., 2017) mrsa/znfe-ldh ph = 8.5 240 70.99 (moaty et al., 2017) chitosan/tife-ldh ph = 8.5 60 98 (mahmoud et al., 2017) co-fe ldh nanoparticle ph = 8.0 360 65-94 (moaty et al., 2017) ha/fe-mn-olb ph = 6.0 720 67.11 (guo et al., 2019) znal-ldh ph = 7.0 120 22.72 this study ha/zna composite ph = 6.0 90 38.76 this study sication of hard-soft electrophile, cd(ii) is categorized as a soft electrophile. therefore, increasing the number of deprotonated carboxylic groups with increasing ph, which is a weak nucleophile, will lower adsorption power (liu et al., 2008). in the base condition, the desorption process on the material is also higher due to hydrophobic interactions, and the oh− ions formed so that they have a higher anity for anion exchange to occur. figure 7. desorption of adsorbent (a) and regeneration of adsorbent (b) the results of the regeneration of each adsorbent on the cd(ii) can be seen in figure 7b. as a similar result of increasing surface area properties after the formation of ha/znal composite, thus adsorption of cd(ii) was higher than starting materials. the eect of the number of additives in this experiment follows the general trend, the greater the number of additives, the higher the adsorption eciency. nevertheless, humic acid has a good adsorption eect. this is because humic acid contains many hydrophilic functional groups, such as hydroxyl and carboxylic groups. the presence of this functional group can increase the solubility of humic acid, which increases the ability of humic acid to adsorb. therefore, ha/znal composite has good adsorption eciency due to its large specic surface area. this may be due to the addition of humic acid to create new adsorption sites. according to rosset et al. (2020) the decrease in adsorption capacity in the regeneration process after repeated cycles, is due to the progressive loss of solid crystallinity during the reconstruction process in layered materials and is caused by the incorporation of residual organic species. basedonseveral typesofadsorbents thathaverecentlybeen found to remove cd(ii) in aqueous solutions in recent years and will compare the adsorption capacity with the adsorbents produced in this paper. in table 4 the adsorption capacity of most of the adsorbents for cd(ii) is between 0 and 150 mg/g. the maximum adsorption capacity of pure znal-ldh was 22.72 mg/g, while the maximum adsorption capacity of ha/znal composite was 38.76 mg/g. overall, ha/znal composite materials are very promising to be used as heavy metal removal adsorbents in aqueous solutions. 4. conclusions modicationofznal-ldhusinghumicacidasasupportmaterial to improve structural stability and adsorption performance has been successfully carried out using a simple coprecipitation method to remove cd(ii) in an aqueous solution. the characterization results suggest that ha/znal composite by sem-edx, xrd, and ftir has a stacked layered structure, a large specic surface area, and many carbon-containing functional groups and the morphology of ha/znal composite showed heterogeneity with some aggregates of ldh. the surface area characterization of ha/znal composite increased the surface area increase greater than ldh pristine. from the results obtained, highest adsorption capacity at ph 6.5 for ldh pristine and ph 6 for composite the removal eciencies © 2021 the authors. page 253 of 255 rahmadan et. al. science and technology indonesia, 6 (2021) 247-255 can reach up to 68.01% and 90.77% respectively. the kinetic parameters corresponding to pso dynamics proved that the adsorption process of cd(ii) on ha/znal composite was most likely chemical adsorption. the equilibrium of cd(ii) adsorption using znal pristine was reached at 120 minutes and the equilibrium of the ha/znal composite was reached at 90 minutes. the adsorption isotherm follows the langmuir model where adsorption occurs in a monolayer and maximum adsorption capacity was obtained 38.76 mg/g higher than pristine. thermodynamic analysis showed that the adsorption of cd(ii) on znal-ldh and ha/znal composite was a spontaneous and endothermic process. additionally, cd(ii) was absorbed on the surface of ha/znal composite by surface complexation and chelating interactions, and surface complexation was the main route for cd(ii) removal. the ha/znal composite was high structural stability on the cd(ii) readsorption process until ve cycles process. all results illustrated that the prepared ha/znal composite has an excellent adsorption performance and is promising for a potential application. 5. acknowledgement the research/publication of this article was funded by dipa of public service agency of universitas sriwijaya 2021. sp dipa-023.17.2.677515 /2021, on november 23, 2020. in accordance with the rector’s decree number: 0014/ un9/ sk.lp2m.pt/2021, on mei 25, 2021. references abate, g. and j. c. masini (2005). inuence of ph, ionic strength and humic acid on adsorption of cd (ii) and pb (ii) onto vermiculite. colloids and surfaces a: physicochemical and engineering aspects, 262(3); 33–39 basu, h., s. saha, i. a. mahadevan, m. v. pimple, and r. k. singhal (2019). humic acid coated cellulose derived from rice husk: a novel biosorbent for the removal of ni and cr. journal of water process engineering, 32; 100892 bukhtiyarova, m. 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miricescu et al., 2019). the commonly used nanomaterials such as cellulose are natural polymers that are abundant in nature. cellulose is a polysaccharide used in various applications due to its advantages, such as being non-toxic and renewable, and aordable processing cost (guo et al., 2012). in addition, cellulose is a strong and rigid polymer that has a high potential to be used as a biopolymer reinforcing agent such as polylactic acid (pla) (rahman et al., 2014). fortunately, pla serves as a drug release because it is a biodegradable polymer that in vitro has good biocompatibility and bio-absorbability (dev et al., 2010). moreover, it has an aliphatic polyester structure (guo et al., 2012). the active component of the drug bound to the pla molecule is highly resistant to degradation, thereby improving its eectiveness (kadian, 2018). this led to the synthesis of cellulose–pla, used in the encapsulation of rifampicin. the steps performed during the process included micro pla, cellulose–pla, and microcapsule https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.263-268&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.263-268 yuwono et. al. science and technology indonesia, 7 (2022) 263-268 syntheses using rifampicin drug. furthermore, ftir, sem, and dissolution test analyses as well as psa were conducted. 2. experimental section 2.1 materials the materials utilized comprise pla, hydrochloric acid, and chloroform obtained from merck & co (nj, usa). cellulose was extracted from cassava bagasse through delignication and applied without further treatment. rifampicin was obtained from a local drug store and was used as purchased. 2.2 synthesis of micro pla the synthesis of micro pla was conducted by dissolving 5 g of pla in 50 ml of chloroform. the solution was stirred with a magnetic stirrer for 4 h. furthermore, 50 ml of ethanol was added, and the solution was stirred using a magnetic stirrer (stuart magnetic stirrer, china) for another 4 h. the solution was evaporated with a rotary evaporator (buchi rotary evaporator, switzerland) until only a small amount of solvent was left. subsequently, 25 ml of distilled water was added and evaporated to get rid of the organic solvent. finally, the micro pla obtained was freeze-dried (scanvac-freeze dryers, denmark). 2.3 synthesis of cellulose–pla the synthesis of cellulose–pla was carried out by combining several methods reported in various studies (dev et al., 2010; jeevitha and kanchana, 2014). firstly, 1 g of cellulose was suspended in 50 ml hcl 3.5 m and stirred with a magnetic stirrer for 2 h at 50◦c. secondly, 5 g of pla was dissolved in 50 ml of chloroform and stirred for 4 h. subsequently, 50 ml of ethanol was added to the pla solution, which was further mixed with the initially prepared cellulose suspension. the cellulose–pla mixture was stirred for 4 h at room temperature and then transferred into a separating funnel. the upper layer, which comprises the chloroform, was removed using a bulb pipette, while the remaining cellulose–pla was ltered with a lter paper and then freeze-dried. the sample was analyzed using ftir (agilent carry 630, ca, usa), psa (fritsch, germany), sem (zeiss evo ma10, germany). 2.4 synthesis of microcapsule meanwhile, approximately 0.65 g of cellulose–pla was dissolvedin6mlofchloroform. consequently, rifampicin(0.002 5 and 0.005 g) was added to the solution, followed by the addition of 50 ml polyvinyl alcohol 0.5%. it should be mentioned that the concentration of rifampicin used is much lower than the normally used dose for curing purpose, since the main objective of this study is to study the potential application of cellulose-pla synthesized as delivery agent. the mixture was stirred for 1 h and dispersed in 250 ml of distilled water. finally, the mixture was stirred for another 1h and then ltered. the solid obtained was then dried for 24 h (chang, 1984). 2.5 slow release test the slow-release test was carried out by dissolving 0.2 g of microcapsules into 500 ml of a buer solution (ph 1.2 kcl-hcl buer, andph7.4phosphatebuer) withaphofrelatively1.2 and 7.4. therefore, for every 3 h interval, 5 ml of each solution, with triplicate sampling at ph of 1.2 and 7.4 was collected and diluted with 25 ml of buer solution. the concentration was measured using a uv–vis shimadzu uv-245 spectrophotometer (japan) at a wavelength of 244 nm (derakhshandeh and soleymani, 2010; ciobanu et al., 2013; siqueira et al., 2010). the drug dissolution rate was further measured using the following formula (1) %d = m × fp × v × 11,000,000 w × 100% (1) where exp: % d (percent dissolution), m (concentration), fp (dilution factor), v (volume), w (mass of microcapsules used). 2.6 characterizations theirspectrawererecordedonkbrdiscswithinthewavenumber range of 4000 to 400 cm−1. the particle size distribution of pla and cellulose–pla were determined using the wet dispersion using water as solvent. sem characterization was conducted on gold coated sample to increase the conductivity. 3. results and discussion 3.1 synthesis of micro pla and cellulose–pla besides, during the synthesis of micro pla, mechanical treatment was adopted. conversely, for the cellulose–pla, a combination of mechanical and acid hydrolysis treatments was utilized. micro pla synthesis was carried out using a magnetic stirrer at a constant rotational speed. one advantage of the mechanical treatment is that the surface charge of the nanomaterial is equivalent to that of the raw material (chang, 1984). conversely, acid hydrolysis treatment was conducted using 3.5 m hcl solution. the acidic solution was used to break down the heterocyclic ether bond between the monosaccharide monomers (siqueira et al., 2010; laopaiboon et al., 2010). the ionic strength of the hcl solution decreased the viscosityofcellulose, therebyreducingthesizeof themacromolecules (czechowska-biskup et al., 2007). although, before mixing the pla and cellulose solution, ethanol was added to the pla solution, which acted as an emulsier. it accumulated on the surface of the hcl and chloroform solution, thereby, causing ethanol to be adsorbed in the solution. in addition, ethanol also decreases the surface and interface strains of each solvent. additionally, during the emulsion process, the molecules of cellulose and plawere collided, therebyfreely interacting with each other (tadros, 2013). the collision frequency increased during the stirring process. electromagnetic induction, which generated rotational motion at a constant angular velocity, enhanced the reaction rate of cellulose and pla (szajnar et al., 2014). © 2022 the authors. page 264 of 268 yuwono et. al. science and technology indonesia, 7 (2022) 263-268 3.2 ftir analysis of cellulose-pla ftir analysis was carried out to determine the functional groups of materials synthesized. the ftir spectra are shown infigure1. figure1(a) shows theabsorptionat3446cm−1 due to the presence of oh from cellulose. in addition, the absorption at 2900 and 1429 cm−1 indicates the c-h bond from the cellulose. these results show that pure cellulose was obtained through the delignication process. this was evidenced by the absence of absorption at 1170 and 1082 cm−1. meanwhile, the absorption of the pyranose ring originated from hemicellulose. in addition, the absence of an alkyl aryl ether bond at 1232 cm−1 indicated that no lignin was bound to the cellulose (yang et al., 2007). this was proven by the absence of absorption at 1599 and 1511 cm−1, indicating a phenylpropanoid ring of lignin (adapa et al., 2011). figure 1(b) shows that the carbonyl group pla is evident at 1757 cm−1, ch3 at 2999 cm−1, and c–h at 2949 and 1458 cm−1. the cellulose–pla spectrum is shown in figure 1(c). furthermore, the presence of absorption at 1759 cm−1 indicates the presence of carbonyl derived from pla. in addition, absorption at 3429 cm−1 implies that a hydroxyl group was derived from the cellulose. the presence of a hydroxy group is indicated by the presence of a band at relatively 3446 and 3429 cm−1 and carbonyl at approximately 1757 and 1759 cm−1, thereby conrming the formation of a bond between the cellulose and pla, while retaining theirbasic functional groups. rahman et al. (2014) reported that the shift in wavenumbers was caused by the intermolecular hydrogen bonds between the cellulose and pla. 3.3 psa of cellulose–pla besides being used to detect particle size, psa was also used to determine the eect of mechanical and acid hydrolysis treatments on micro-particle synthesis. the results of the eect of psa on pla and cellulose–pla is shown in figure 2. in accordance with figure 2(a), pla has 3 clusters of particles. the particle sizes in the rst cluster range within 0.36 and 2.86 `m, with a relative percentage of 11.75%. the second cluster overlappedwith the thirdandtheparticle sizes rangingbetween 7.74 and 205`m, with a relative percentage of 87.18%. however, considering the cellulose–pla (figure 2(b)), the result showed that the sample size is much smaller while displaying a slightly narrower distribution. based on the diagram, the particle size of the main cluster in the sample ranges within 8.30 to 37.86`m with a relative percentage of 90.55%. this nding suggests that cellulose and pla were combined to form a more compact material leading to the collapse of overlapping due to the mechanical and hydrolysis treatment during the preparation process. in respect to this, it was proven that a combination of mechanical and acid hydrolysis treatments improved the eectiveness of micro material synthesis. mechanical treatment increased the frequency of polymer collisions in a solvent, thereby accelerating solvation. acid hydrolysis treatment accelerated bonding by protonating polymer bonds. in this study, it is evident that the particle size of the prefigure 1. ftir spectra of (a) cellulose, (b) pla, (c) cellulosepla pared sample is within the micrometer (`m) range and significantly larger than the ndings of the research carried out by kumar et al. (2012), which reported that the preparation of co-ethyl cellulose–pla had particle sizes within the nanometer (nm) range. these signicantly dierent results were most likely realized due to the dissimilarities in the starting materials utilized. 3.4 sem analysis of cellulose-pla sem analysis was carried out to conrm the result of the cellulose–plasynthesis morphologically, shown in figure 3. based on figure 3(a), pla has sheet morphology; this was due to the addition of chloroform. this solvent was diused and adsorbed in the pla 3-dimensional network, thereby breaking thecross-link. toconrmthisnotion, itwasdiscovered that the density between pla sheets was quite high. the chloroform disconnected the intermolecular, both physically and chemically. figure 3(b) shows that the cellulose obtained throughthe delignication process has a rod-like structure. in addition, its intermolecular density was extremely high, indicating that the cellulose possesses a microcrystalline structure. cellulose polymers possess uniform agglomeration due to the intramolecular © 2022 the authors. page 265 of 268 yuwono et. al. science and technology indonesia, 7 (2022) 263-268 figure 2. psa analysis (a) pla, (b) cellulose-pla figure 3. sem analysis (a) pla, (b) cellulose, (c) cellulosepla hydrogen bonds. meanwhile, the cellulose microcrystal was composedofhundredsofagglomerationofcellulosenanobrils with a rod-like structure (rahman et al., 2014). based on figure 3(c), the cellulose bounded into pla particles has a smooth surface. the cellulose suspension process in the hcl was stirred in order to reduce agglomeration by hydrolyzing and breaking the intramolecular hydrogen bonds, thereby causing the inter-particle spacing to become more tenuous than that in figure 3(b). it was also discovered that the density of the pla particles attached to the cellulose was more tenuous than that in figure 3(a) due to the hcl solvent hydrolyzed ether bonds on the pla. the acid solution used was capable of hydrolyzing the long-chain cellulose in the amorphous part, thereby producing a crystalline structure. on the contrary, the crystalline part was resistant to acid attack (khoo et al., 2016). the addition of cellulose caused the pla structure to become more fragile than pure one (sullivan et al., 2015), thereby increasing its dissolution ability in the body. 3.5 dissolution test the dissolution test was carried out using rifampicin to determine the extent of its detachment from the micro material. figure 4. dissolution test of rifampicin concentration (a) 0.3% and (b) 0.6% rifampicin was selected because of its easy accessibility. the dissolution test was carried out at aph of 1.2, which is regarded as a simulation of the stomach and intestinal ph of 7.4, carried out for 15 h. the dissolution test results are shown in figure 4. figure 4(a) shows the percentage dissolution of pla-cellulose-drug 0.3% at a ph of 7.4 and 1.2. the optimum time for drug dissolution at the same ph was 12 h. furthermore, relatively 8.42% and 3.81% of the drugs were dissolved at a ph of 7.4, and 1.2 respectively. in addition, drug dissolution occurred more at a ph of 7.4 than 1.2. the percentage dissolution of pla-cellulose-drug of 0.6%, is shown in figure 4(b). the optimum time fordrug dissolution at a ph of 7.4 was 15 h. in addition, approximately 2.03% of the drugs were dissolved. conversely, the optimum time for drug dissolution at a ph of 1.2 was 12 h. furthermore, approximately 6.69% of the drugs were dissolved. therefore, the drug dissolution occurred more at ph 1.2 than 7.4. an eective microcapsule used for tb treatment is cellulose-pla-drug 0.3%. conversely, several nanomaterial drugs were not degraded in the stomach, they were easily degraded in the lungs. the presence of a nanomaterial improved the eectiveness of the treatment and reduced the tb drug resistance causedbygeneticmutations (shakyaetal.,2012). basedonthe data in figure 4, the optimum dissolution time for rifampicin is 12 h. this is consistent with the studycarried out bysarfaraz et al. (2010) which stated that after 12 h, approximately 69% to 91% of rifampicin was deformed. amirah et al. (2014) reported that the optimum dissolution time for rifampin is 10 h. the dissolution rate on the rst day was aected by several factors, such as diusion through the cellulose–pla channel. in addition, terminal carboxylic acids improved water absorption, thereby accelerating swelling and cellulose–pla degradation © 2022 the authors. page 266 of 268 yuwono et. al. science and technology indonesia, 7 (2022) 263-268 (fonseca et al., 2002). the dissolution rate was also aected by the large surface area of the material (nag et al., 2016). 4. conclusions in this research cellulose-pla was successfully synthesized from cellulose isolated from cassava bagasse and commercial pla.theformationofbondbetweenthe twostartingmaterials was conrmed by ft-ir analysis as indicated by the presence of absorption bands at 3445 and 3429 cm−1 associatied with hydroxyl group and the band at 1757 and 1759cm−1 associated with carbonyl group. psa analysis indicated the reduction of particle size of cellulose-pla compared to those of cellulose and pla, conrming the formation of cellulose-pla microcapsule. the formation of cellulose-pla microcapsule was also conrmed by surface morphology of the samples as seen by sem. the dissolution test carried out two dierent concentrations of ripamcin revealed that the optimum dissolution (8.42%) was achieved with cellulose–pla of 0.3%, dissolution time of 12 h, and ph of 7.4. 5. acknowledgment the authors would like to thankto the institute of research and communityservices, universitas lampungthat provided fund for this project to be undertaken through research program of masterplan for acceleration and expansion of indonesia’s economic development, 2016. the authors would like to thank enago (www.enago.com) for the english language proofread and review. references adapa, p., l. schonenau, t. canam, and t. dumonceaux (2011). quantitative analysis of lignocellulosic components of non-treated and steam exploded barley, canola, oat and wheat straw using fourier transform infrared spectroscopy. journal of agricultural science and technology, 1; 177 amirah, m., a. amirul, and h. wahab (2014). formulation and characterization of rifampicin-loaded p (3hbco-4hb) nanoparticles. international journal of pharmacy and pharmaceutical sciences, 6(4); 140–6 chang, t. m. s. 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(2013). emulsion formation and stability. john wiley & sons world health organization (2016). global tuberculosis report. world health organization yang, h., r. yan, h. chen, d. h. lee, and c. zheng (2007). characteristics of hemicellulose, cellulose and lignin pyrolysis. fuel, 86(12-13); 1781–1788 © 2022 the authors. page 268 of 268 introduction experimental section materials synthesis of micro pla synthesis of cellulose–pla synthesis of microcapsule slow release test characterizations results and discussion synthesis of micro pla and cellulose–pla ftir analysis of cellulose-pla psa of cellulose–pla sem analysis of cellulose-pla dissolution test conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper optimization of antibacterial production of endophytic fungi with various sources of c, n, and ph using the response surface methodology hary widjajanti1*, elisa nurnawati1, muharni1, eca desriana zahwa1 1department of biology, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia *corresponding author e-mail: hary_widjajanti@unsri.ac.id abstract secondary metabolites extract of mcb1 endophytic fungi from gelam (melaleuca cajuputi powell.) leaves have a high potential antibacterialactivityagainstescherichiacoliatcc8739andstaphylococcusaureusatcc6538withflavonoidsandphenolasbioactive compounds. thelowproductionofsecondarymetabolitesextract inthecultivationstageandthehighpotentialantibacterialactivity of bioactive compounds produced by mcb1 endophytic fungi require special treatment for optimizing the secondary metabolites product. this ispossiblyachievedbyoptimizingthecompositionofthecultivationmedia, wherevarioussourcesofcarbon, nitrogen, and ph produce different amounts and classes of secondary metabolites. the objectives of the research are to obtain the optimum interactionbetweensourcesofcarbon,nitrogen, andphfortheproductionofsecondarymetaboliteextractusingresponsesurface methodology (rsm). the results showed that the highest extract (0.250 g) with the composition of sucrose as carbon source, yeast extract as nitrogen source, and ph 6. the optimization of the cultivation medium with composition 4.500 g/l sucrose, 0.480 g/l yeast extract, and ph 6.1 yielded 0.340 g secondary metabolites extract of mcb1 endophytic fungi. the chromatogram profile of the optimized secondary metabolite extract revealed the presence of flavonoids, phenols, terpenoids, and tannins. keywords endophytic fungi, antibacterial compound, response surface methodology (rsm) received: 13 november 2021, accepted: 8 february 2022 https://doi.org/10.26554/sti.2022.7.2.149-157 1. introduction endophytic fungi live in plant tissues at a certain time to form colonies and produce the same bioactive compounds as the host plants, due to the genetic transfer followed by the coevolution process (je�rey et al., 2008). from the result of previous research the mcb1 endophytic fungi of gelam leaves produced secondary metabolites as antibacterial against escherichia coli with a minimum inhibitory concentration (mic) of 100 `g/ml, metabolite extract of 0.250 g, and fungal biomass of 2.340 g (widjajanti et al., 2019). e�orts are required to increase the low production of secondary metabolites at the cultivation stage 0,250 g/l and the potential for the activity of bioactive compounds produced by modifying the cultivation media composition. meanwhile, the di�erences in the composition of the cultivation media lead to di�erent amounts of metabolites and their pro�les. discovering the most optimal conditions in the growth process and the formation of secondary metabolites from isolates is the basis for optimizing cultivation media (goutam et al., 2014), which is achieved by modifying the carbon, nitrogen source, and ph (septiana et al., 2017). carbon source is an important basic nutrient for fungi which is used as the main structure in providing energy for cell growth in metabolic processes. sucrose as a carbon source also greatly a�ects the formation of antimicrobial compounds in endophytic fungi from moringa oleifera plants (arora and kaur, 2019). previous studies used glucose as carbon sources and increased the production of secondary metabolites in the form of beauvericin in fusarium oxysporum (lee et al., 2008) and fusarium rodolens (xu et al., 2009). the highest biosynthesis of �avonoid compounds was found after the use of dextrose as a carbon source in isolates of the fungus aspergillus tamarii (bose et al., 2019). in some cases the growth of the source fungi and the nitrogen concentration greatly a�ect the production of secondary metabolites, it is often carried out several related studies to �nd the best nitrogen source in the formation of secondary metabolites. in this case, the most commonly used nitrogen sources are yeast extract, peptone, and sodium nitrate which are added to fungal nutrition (arora et al., 2012). the optimal growth of fungi in the ph range of 5-8 (gupta et al., 2010). secondary metabolite production in the fungal https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.149-157&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.149-157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 group that fusarium incarnatum produces the most optimum pigment at ph 5 (himalini and razia, 2018), while secondary metabolites were produced at the most optimum in geosmithia pallida (deka and jha, 2018) and fusarium solani at ph 6 merlin et al. (2013). the condition of ph 7 greatly a�ects the formation of antimicrobial compounds in endophytic fungi moringa oleifera (arora and kaur, 2019) while at ph 8 greatly a�ects the formation of naphthoquinones pigments in fusarium verticilioides (boonyapranai et al., 2008). the cultivation media can be optimized using response surface methodology (rsm) to obtain the optimum factors. it also analyzes the secondary metabolite formation response in�uenced by several independent variables to enhance the response examined (qiu et al., 2012). the fungus aspergillus niger ke1 produced the highest lipase enzyme with an optimum nutritional composition that had been analyzed using rsm, namely 2% peptone, 0.100% olive oil, 0.500% glucose and 0.075% mgso4.7h2o (ilmi , 2021). the endophytic fungus dichotomopilus funicola y3 isolated from pigeon pea (cajanus cajan) produced 4.9 times higher vitexin of 78.890 mg/l with the optimum media composition determined by rsm, namely 0.060 g/l l-phenylalanine, 0.21 g/l salicylic acid, and 0.19 g/l cuso4·5h2o (gu et al., 2018). in this study, we will try to optimize the growth medium by experimenting with variations in carbon, nitrogen, and ph sources using rsm in the hope that higher metabolite products will be obtained. acording to bezerra et al. (2008) response surface methodology (rsm) is a combination of mathematical and statistical techniques based on the compatibility of polynomial equations with experimental data that must describe a data set with the aim of predicting statistically. because of its high e�ciency in fermentation, media composition, and process conditions, the rsm method was chosen. furthermore, it can explain the interaction of variables, and its accuracy is high (kiran et al., 2016; palukurty and somalanka, 2016; karthikeyan et al., 2010). rsm can be applied if a response is in�uenced by several variables, the aim is to optimize the interaction of these variables so that the best results are obtained. the objectives of the research to obtain the optimum interaction between sources of carbon, nitrogen, and ph for the production of secondary metabolite extract using response surface methodology (rsm). 2. experimental section 2.1 materials pure culture of mcb1 endophytic fungi from the previous research that isolated from melaleuca cajuputi leaves. 2.2 methods 2.2.1 propagation of endophytic fungi pure culture of mcb1 endophytic fungi were propagated on pda medium in test tubes and petri dish for stock and working cultures. subsequently, it was incubated at room temperature until the fungi grew for aproximately 5-7 days. 2.2.2 selection of carbon, nitrogen sources, and ph potato dextrose broth medium with composition of potato 200 g/l, peptone 0.500 g/l, yeast extract 0.800 g/l, (nh4)2 so4 3 g/l, kh2po4 2 g/l, 0.500 g/l mgso4, 0.010 g/l phenylalanine, and 4% (w/v) carbon source (merlin et al., 2013) used in cultivation. in the selection of carbon sources, the medium was modi�ed by using carbon sources in the form of glucose, dextrose and sucrose. in the selection of nitrogen sources, the medium was modi�ed by using nitrogen sources in the form of peptone, yeast extract, and sodium nitrate. in the selection of ph, the medium was modi�ed by using variation ph 5, 6, 7, and 8. 2.2.3 optimizationofcultivationmediumcompositionwith response surface methodology (rsm) the composition of the cultivation medium is optimized using response surface methodology, and it includes three selected variables: carbon, nitrogen, and ph. the data of the selection from the previous test was used to determine the upper and lower limits of the central composite design (ccd). this is also useful in the rsm method with the design-expert 7.0 from stat-ease (qiu et al., 2012). this stage consisted of 9 fractional factorial points 23 for a factorial design compiling from 3 variables, which is enlarged by 6 starting and 5 center points. the total of all experimental units in this stage was 19 and was optimized using the cultivation medium composition of potato 200 g/l, yeast extract 0.800 g/l, (nh4)2so4 3 g/l, kh2po4 2 g/l, mgso4 0.500 g/l, phenylalanine 0.010 g/l, sources of carbon, nitrogen, and ph determined by central composite design (ccd). 2.2.4 extraction of endophytic fungi secondary metabolite the biomass of endophytic fungi was separated from the optimization medium using �lter paper. the liquid-liquid fractionation (partition) was carried out with ethyl acetate solvent in a ratio of 1:1 and the extract collected was concentrated with a rotary evaporator to obtain the ethyl acetate extract of endophytic fungi. subsequently, the separated biomass was dried using an oven to obtain the dry weight (bhardwaj et al., 2015). 2.2.5 thin layer chromatography (tlc) the optimized extract from mcb1 endophytic fungi was dissolved with ethyl acetate, spotted with a capillary pipette on a tlc plate (tlc, silica gel 60 f254, merck), and eluted in a chamber that contained eluent with a ratio of n-hexane: ethyl acetate 3:2. when the eluent reached the boundary line to form a tlc chromatogram pattern, the plate was removed and the stain formed was viewed using 366 nm uv light. for visualization observations, it was sprayed with 5% h2so4 reagent and heated on a hot plate at a temperature of 80°c. the stains formed were identi�ed through color spots and the rf value (retardation factor) was determined using the formula below (bele and khale, 2011): © 2022 the authors. page 150 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 rf = distance traveled by component distance traveled by solven 2.2.6 data analysis data was analyzed with analysis of variance (anova) at u 0.050. 3. result and discussion 3.1 the carbon source for mcb1 endophytic fungi mcb1 endophytic fungi grew and produced secondary metabolites on all sources of sucrose, dextrose, or glucose. meanwhile, the weight of the ethyl acetate extract and the mass of biomass produced were shown in figure 1. after 30 days of cultivation, the highest extract yielded and biomass weight was 0.250 g and 2.450 g with a carbon source of dextrose and sucrose, respectively. monosaccharides were found to be the most e�ective carbon source for fungal growth. this is also evidenced in a similar study in bose et al. (2019) that, dextrose is a simple type of carbon that can be metabolized by fungi more easily compared to other carbon sources. the metabolism process of monosaccharide-type carbon sources is easily broken down by the fungus isolate used quickly, characterized by the highest fungal biomass weight, this causes the dextrose concentration to decrease in the cultivation media. after the dextrose carbon source is depleted, the fungus regulates the use of other carbon sources in the media to be used for the formation of secondary metabolites in the idiophase. this is explained in stanbury and whitaker (1987) that the limited carbon concentration will induce the formation of secondary metabolites, limited carbon is indicated due to fast metabolism for cell growth. figure 1. fungal biomass and extract weight from carbon source optimization sucrose belongs to the disaccharide group which is broken down into glucose and fructose by enzymes before it is metabolized by fungi. according to mao et al. (2005), this occurs through the use of substrates with a slow metabolism by fungi due to the inability to hydrolyze, characterized by non-optimal cell growth. meanwhile, the formation of secondary metabolites is induced by slow growth due to the depletion of the main carbon source. figure 1 shows the biomass of mcb1 endophytic fungi which is not directly proportional to the secondary metabolites production. the use of sucrose produced a lower weight of biomass than dextrose, however, this is not shown in the production of secondary metabolites. furthermore, high biomass weight did not produce higher secondary metabolite weight because cell growth has no relationship with their formation. according to sanchez et al. (2010), biomass is formed at the cell growth stage which is dominantly synthesized at the exponential phase, while secondary metabolites are at the stationary to the lag phases. 3.2 the nitrogen source for mcb1 endophytic fungi mcb1 endophytic fungi also grew and produced secondary metabolites on all nitrogen sources, namely peptone, yeast extract, and nano3. the weight of the ethyl acetate extract and biomass produced are shown in figure 2. after 30 days of cultivation, the highest extract and biomass weight were 0.390 and 1.360 g with nitrogen sources in form of yeast extract and peptone, respectively. the highest metabolite production was obtained after the use of yeast extract, which did not produce maximum fungal biomass, however, there was high production of biomass from peptone. merlin et al. (2013) stated that the highest secondary metabolites production by the endophytic fungi of fusarium solani was observed after the use of yeast extract. according to septiana and simanjuntak (2017), yeast extract is the best nitrogen source in producing antioxidant compounds by isolates of endophytic fungi from turmeric roots. described by wang et al. (1979), the amino acids found in yeast extract and peptone contain glutamic acid, glutamine, cysteine, methionine, arginine, asparagine, proline, and phenylalanine. besides containing amino acids, yeast extract also contains several minerals such as sodium, chloride, calcium, magnesium, potassium phosphate, and sulfate as elements used in the growth process by fungi. figure 2. optimization of nitrogen source yields fungal biomass and extract weight 3.3 ph range for mcb1 endophytic fungi the mcb1 endophytic fungi were able to grow and produce secondary metabolites at all tested ph values, which include © 2022 the authors. page 151 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 6, 7, and 8. the extract weight of the ethyl acetate and fungi biomass produced with variations in ph are shown in figure 3. after 30 days of cultivation, the highest extract was 0.560 g at ph 6, while the biomass weight was 2.270 g at ph 7. since the most optimum secondary metabolite production was obtained at ph 6, therefore, the fungi produced maximally in acidic ph. it has been previously examined by gazi and kanda (2004) that cell growth and the formation of secondary metabolites in fungi tend to be produced at optimal ph with a range of 5-7. research conducted by merlin et al. (2013) also found that the isolates from the endophytic fungi of fusarium solani formed the highest secondary metabolites at ph 6. figure 3. fungal biomass and extract weight as a result of ph optimization acording to rousk et al. (2009) ph a�ects the growth of fungi, starting from the growth of mycelium or the growth of fruiting bodies. the ph will a�ect the permeability of the fungal membrane, therefore the fungus will be unable to absorb important nutrients when a certain ph is not suitable. acording to arora and chandra (2010) the inhibition of the nutrient uptake process will a�ect the metabolic rate of the fungus. ph also related to the permeability characteristics of the fungal membrane so that it a�ects the uptake and loss of ions in media nutrient for their growth. the e�ect of ph on secondary metabolite production varies greatly depending on the fungus species. the production of quinidine increased considerably in fusarium solani at an initial ph of 6.2, but not in diaporthe sp. at an initial ph of 6.8 (rahmawati et al., 2021). 3.4 results of cultivation medium optimization for mcb1 endophytic fungi in mcb1 endophytic fungi, three factors were used to a�ect the weight of secondary metabolite extract with sucrose as carbon source with a value ranging from 0.360 g/l to 0.680 g/l and yeast extract as nitrogen source with a value between 0.160 g/l to 0.830 g/l, while the ph ranges from 5.1 to 6.8. meanwhile, the range and level of the factors used can be reviewed in table 1. the extract weight of the ethyl acetate and biomass of endophytic fungi optimized using sucrose, yeast extract, and ph are presented in table 2. the 19 treatment points of the design gave a response in form of the mcb1 endophytic fungi extract weight, as presented table 1. the composition of medium optimization for the mcb1 endophytic fungi and the range of factors tested optimization factor range and level -1.680 -1 0 1 1.680 sucrose (g/l) 0.630 2 4 6 7.360 yeast extract (g/l) 0.160 0.300 0.500 0.700 0.830 ph 5.1 5.5 6 6.5 6.8 in table 2. the highest extract weight was obtained in the center point at the 17th standard with the metabolite extract weight of 0.390 g. figure 4. 3d-surface graphics for surface and contour responses the surface of mcb1 endophytic fungi extract. (a) 3d-surface graphics for response surface (b) contour graph for response surface 3.5 response model of mcb1 endophytic fungi the data model was selected based on the response from the weight of the secondary metabolite extract by reading the results of the sequential analysis of the sum of squares in line with the smallest p-value (p>0.050). according to the analysis of the summary statistics and the sequential sum of the square, it was concluded that the appropriate model was selected by the pro© 2022 the authors. page 152 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 table 2. weight of mcb1 endophytic fungi extract from cultivation medium optimization with 3 factors using rsm standard sucrose (x1, g/l) yeast extract (x2, g/l) ph (x3 ) extract weight (y, g) 1 2 0.300 5.5 0.130 2 6 0.300 5.5 0.180 3 2 0.700 5.5 0.090 4 6 0.700 5.5 0.230 5 2 0.300 6.5 0.290 6 6 0.300 6.5 0.270 7 2 0.700 6.5 0.100 8 6 0.700 6.5 0.190 9 0.630 0.500 6 0.110 10 7.360 0.500 6 0.270 11 4 0.160 6 0.160 12 4 0.830 6 0.250 13 4 0.500 5.1 0.180 14 4 0.500 6.8 0.250 15 4 0.500 6 0.280 16 4 0.500 6 0.360 17 4 0.500 6 0.390 18 4 0.500 6 0.340 19 4 0.500 6 0.31 gram. this was conducted to determine the optimum response of the secondary metabolite of the mcb1 endophytic fungi and explain the relationship between the three factors. therefore, the quadratic model in the selection analysis represented the most appropriate model used in this research. 3.6 results of analysis of variance (anova) and interaction between factors on the response of mcb1 endophytic fungi based on the data processing using design expert 11.0.0 and analysis of variance (anova), the yeast extract, ph, and the 2fi model (interaction between 2 factors) have insigni�cant values. as shown in the table, each p-value has 0.551, 0.086, 0.170, 0.394 and 0.067, respectively, where p>0.050. this indicated that the use of nitrogen sources such as yeast extract, variations in ph, and the relationship between the two factors did not a�ect the production of secondary metabolites. according tobaş and boyacı (2007), a signi�cant data model provides accurate data to explain the relationship between the dependent and independent variables in the response surface analysis method. the use of a carbon source in form of sucrose had a signi�cant value of 0.015 where p <0.050, which a�ected the production of secondary metabolite extracts. similarly, the use of sucrose a�ected on the formation of secondary metabolites of mcb1 endophytic fungi. this is because sucrose is a disaccharide that is di�cult to synthesize and is not favored by fungi. therefore, other carbon sources are used until the condition of the �rst preferred source is exhausted, which causes metabolic imbalance and physiological stress. martin and demain (1980) stated that in a medium, a carbon source such as sucrose is used figure 5. results of tlc on secondary metabolite extract of mcb1 endophytic fungi (a) tlc of mcb1 endophytic fungi extracts at 366 nm uv light (b) chromatogram of mcb1 endophytic fungi extract after spraying h2s04 5% longer by fungi and after the preferred source, while the latter is used for the biosynthesis of secondary metabolites. the use of sucrose, yeast extract, and ph is shown in form of contour plots and response surface graphs in figure 4. based on the analysis, there is an increase in the concentration of sucrose from 0.680 g to 4 g and yeast extract from 0.160 to 0.500 g. furthermore, the use of sucrose more than 4 g and yeast extracts more than 0.500 g can reduce the production of secondary metabolites. the optimum concentration to increase the production of metabolites were 4 g of sucrose and 0.500 g of yeast extract. this decrease in production was explained by tudzynski (2014) which stated that some nitrogen and excess © 2022 the authors. page 153 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 table 3. composition formula for medium optimization of mcb1 endophytic fungi isolate sucrose yeast extract ph secondary metabolites desirability level 4.500 g/l 0.480 g/l 6.1 0.340 g 0.853 carbon sources used in the cultivation medium cause inhibition of secondary metabolite formation by the substrate. since these conditions signi�cantly a�ect the speci�c growth process, the cell growth rate becomes constant and there is no physiological imbalance that induces the formation of secondary metabolites leading to inhibition by the substrate. figure 6. the mechanism for the biosynthesis of terpenoids through the mevalonic acid pathway (flynn and schmidt-dannert, 2018) based on the anova yeast extract, ph and the 2fi model (interaction between 2 factors) have nonsigni�cant values. each p-value shown in the table is 0.551, 0.086, 0.170, 0.394 and 0.067 where p>0.050. this indicates that the use factor nitrogen source in the form of yeast extract, variations in ph and the relationship between the two factors did not a�ect the production of secondary metabolites of mcb1 fungal isolate. based on figure 4, as the ph value increases from 5.5 to 6.5, the production of secondary metabolites also increases, and the optimum value is obtained at ph 6. according to arora and chandra (2010), the appropriate ph is among the factors that determine growth, product formation, and enzymes used in metabolic processes. the optimum ph under within the acidity range was able to a�ect the work of the enzymes produced. this showed that fungi can grow optimally and produce secondary metabolites at a ph within the acidic range. 3.7 the formulation for medium optimization of mcb1 endophytic fungi figure 7 provides optimal point solutions for each factor suggested by design expert 11.0.0. meanwhile, the production of secondary metabolites was increased with in�uencing factors, namely sucrose, yeast extract, and ph range using the design expert 11.0.0 program with the speci�ed limits to produce the optimum value. the criteria for optimizing the response to the production of secondary metabolites are adjusted to the limits in table 3. the mathematical model for the secondary metabolite production of mcb1 endophytic fungi obtained in the optimization was y= -8.297 + 0.185x1 + 3.022x2 + 2.443x3 + 0.062x1x2 0.015x1x3 0.350x2x3 – 0.013x12 1.213x22 0.179 x32, where the variables with the most optimum response were sucrose (x1) of 4.500 g/l, yeast extract (x2) of 0.480 g/l and ph (x3) of 6.1. moreover, the estimated response obtained was 0.340 g with a desirability of 0.853, which is approximately 1. according to raissi and farsani (2009), desirability is a value showing the program’s ability to ful�ll the desires based on the criteria set on the �nal product. therefore, the most optimal formula accepted is that with the maximum desirability value in a range of 0 to 1. the desirability value closer to 1 indicates that the program’s ability to produce the desired product is getting more perfect. 3.8 tlc secondary metabolite extract from optimization of mcb1 endophytic fungi thin-layer chromatography was used to examine the optimized secondary metabolite extract (tlc). the fungi produced secondary metabolites from several groups of compounds as the medium composition of the cultivation process changed, including phenols, �avonoids, terpenoids, and tannins (figure 5). the bioactive compounds were identi�ed by examining the color spots formed on the tlc plate. based on figure 5, the secondary metabolite extract of the mcb1 endophytic fungi in tlc obtained yellow phenol compounds and �avonoids with an orange color. according to bungihan and matias (2013), yellow-colored compounds are classi�ed as phenolic, while �avonoids have a brownish-yellow to red color. furthermore, the two other spots observed were blackish-brown spot which was identi�ed as tannins, while purple spots were identi�ed as terpenoid. bioactive compounds from the tannin group form green, brown to black spots, while terpenoid formed pink to purple or violet after being sprayed with 5% h2so4 and heated. © 2022 the authors. page 154 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 figure 7. the mechanism of tannin biosynthesis through the shikimic acid pathway (tohge et al., 2013) based on the results of tlc (figure 5), two new groups of the compound were added, namely terpenoids and tannins were added to the secondary metabolite compounds of the mcb1 endophytic fungi. in widjajanti et al. (2019), the group of compounds produced by mcb1 endophytic fungi was phenolic and �avonoids, due to changes in the composition of the cultivation medium used. in a previous study, cultivation used the pdb medium (200 g of potatoes and 20 g of glucose in 1 l of distilled water). in the optimization, a medium with a more complete composition was used (200 g potato, 4 g sucrose, 0.800 g yeast extract, 3 g (nh4)2so4, 0.500 g mgso4, 0.010 g phenylalanine in 1 l of aquadest). abo-elmagd (2014) also stated that the nutrient source can induce or eliminate a metabolite compound produced by fungi. the terpenoid group is formed due to di�erences in the composition of the carbon source. the formation of acetic acid in cellular processes is in�uenced by carbon metabolism. hence, it was used as a substrate in primary metabolism to produce acetyl coa as the main ingredient in the formation of terpenoid compounds during the biosynthesis of the mevalonic acid pathway (figure 6). according to agusta (2006) and flynn and schmidt-dannert (2018), acetic acid was condensed to produce acetyl coenzyme a, after activation, which is the reaction step of terpenoid biosynthetic. the reaction of acetyl coenzyme a produced isopentenyl pyrophosphate (ipp), which is isomerized into dimethyl allyl pyrophosphate (dmapp) by the isomerase enzyme. moreover, ipp is an active isoprene unit that combined head-to-tail with dmapp, which is the �rst step of isoprene polymerization to produce terpenoids. based on the chromatogram pro�le, blackish-brown spots formed were assumed to be tannin compounds, due to the use of l-phenylalanine in the composition of the medium optimization. meanwhile, the use of l-phenylalanine as a precursor for the formation of tannins is presented in figure 7. according to tohge et al. (2013), the shikimic acid pathway is used in the synthesis of hydrolyzable tannin groups and compounds based on the amino acid phenylalanine. since the amino acid phenylalanine is used in the formation of gallic acid, therefore, the tannins are formed through esteri�ed gallic acid derivatives. from fungus mcb1 isolate tannin support as an antibacterial compound. 4. conclusion the optimization of the cultivation medium with composition 4.500 g/l sucrose, 0.480 g/l yeast extract, and ph 6.1 yielded 0.340 g secondary metabolites extract of mcb1 endophytic fungi. the optimized secondary metabolite extract’s chromatogram pro�le revealed the presence of �avonoids, phenols, terpenoids, and tannins. the chromatogram pro�le of the optimized secondary metabolite extract showed the presence of �avonoids, phenols, terpenoids, and tannins that as an antibacterial. © 2022 the authors. page 155 of 157 widjajanti et. al. science and technology indonesia, 7 (2022) 149-157 5. acknowledgement the dipa of the public service agency of universitas sriwijaya 2021 funded the research and publication of this article. sp dipa-023.17.2.677515/2021, on november 23, 2020. in accordance with the rector’s decree number: 0010/un9/sk.lp2m.pt/2021, on april 28, 2021. references abo-elmagd, h. i. 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(2014). nitrogen regulation of fungal secondary metabolism in fungi. frontiers in microbiology, 5; 656 wang, d. i., c. cooney, a. demain, p. dunhill, a. humprey, and m. lily (1979). fermentation and enzyme technology. london: willey interscience widjajanti, h., n. salni, e. nastiti, and nurnawati (2019). screening endophytic fungi of melaleuca cajuputi powell leaves as an antibacterial sources. in proceeding of the 1st international mipanet conference on science and mathematics (imc-scimath) xu, l. j., y. s. liu, l. g. zhou, and j. y. wu (2009). enhanced beauvericin production with in situ adsorption in mycelial liquid culture of fusariumredolens dzf2. processbiochemistry, 44(10); 1063–1067 © 2022 the authors. page 157 of 157 introduction experimental section materials methods propagation of endophytic fungi selection of carbon, nitrogen sources, and ph optimization of cultivation medium composition with response surface methodology (rsm) extraction of endophytic fungi secondary metabolite thin layer chromatography (tlc) data analysis result and discussion the carbon source for mcb1 endophytic fungi the nitrogen source for mcb1 endophytic fungi ph range for mcb1 endophytic fungi results of cultivation medium optimization for mcb1 endophytic fungi response model of mcb1 endophytic fungi results of analysis of variance (anova) and interaction between factors on the response of mcb1 endophytic fungi the formulation for medium optimization of mcb1 endophytic fungi tlc secondary metabolite extract from optimization of mcb1 endophytic fungi conclusion acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper mg/al-chitosan as a selective adsorbent in the removal of methylene blue from aqueous solutions patimah mega syah bahar nur siregar1, aldes lesbani2, risfidian mohadi3* 1magister programme graduate school of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia2research center of inorganic materials and complexes, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia3graduate school of faculty mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia *corresponding author: risfidian.mohadi@unsri.ac.id abstractthe use of dyes in the textile industry is detrimental to aquatic biota and humans. pollution caused by dye waste can be overcomeby adsorption methods using adsorbents such as ldh. ldh is known as an adsorbent that is often found in the process of removingdye waste, but repeated use is not effective. this can be overcome by the ldh modification process using a supporting material suchas chitosan. modification of ldh can be done using coprecipitation or precipitation simultaneously at ph 10. xrd analysis where thepeaks that appear in mg/al-chitosan are similar to the typical peaks of the constituent materials, namely mg/al and chitosan. this isconfirmed by ftir analysis where the spectrum that appears in mg/al-chitosan is similar to the spectrum in mg/al and chitosan. aswell as bet analysis where there is an increase in the surface area of mg/al after being modified to mg/al-chitosan from 5.845 m2/gto 24.556 m2/g. in this study, the selectivity process for the dye mixture was carried out first with the most selective dye for themg/al-chitosan adsorbent was methylene blue. methylene blue was continued for adsorption processes such as isotherm adsorptionkinetics and adsorption thermodynamics as well as adsorbent regeneration studies. the results showed that at 90 minutes theadsorption reached equilibrium. the adsorption capacity of mg/al increased after modification using chitosan from 84.746 mg/gto 108.696 mg/g. the adsorption process follows the langmuir isotherm type where adsorption occurs chemically (monolayer).regeneration studies show that mg/al-chitosan is an adsorbent that can be used repeatedly with stable adsorption effectivenessuntil the fifth cycle. keywordsadsorption, selectivity, methylene blue, regeneration received: 4 november 2021, accepted: 23 february 2022 https://doi.org/10.26554/sti.2022.7.2.170-178 1. introduction theincreasinguseofdyes invarious industries suchas foodand textiles can cause serious environmental problems. disposal of large volumes of waste into the environment causes adverse eects on aquatic ecosystems and human life. this pollution will reduce the quality of the waters so that the biota living in the aquatic environment will also be threatened. this problem is getting worse because the dye is biologically dicult to decompose, so the polluted dye must be reduced in concentration and removed from the aquatic environment (el-mekkawi et al., 2016). one of the synthetic dyes that are harmful to health is methylene blue. methylene blue (mb) is a basic dye that is relatively cheap compared to other dyes, so it is often used in chemistry, biology, medicine, and the coloring industry (sagita et al., 2021). methylene blue (figure 1) is a cationic dye that is soluble in water. these dyes may cause eye irritation and skin, systemic eects including blood changes. in addition, exposure to methylene blue at certain levels can cause vomiting, nausea, diarrhea, dizziness, excessive sweating, and digestive inammation (wei et al., 2015). figure 1. methylene blue (mb) the negative impact of the use of dyes resulted in dye https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.170-178&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.170-178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 waste being processed rst before being discharged into the environment (kulkarni and kaware, 2014). wastewater treatment aims to eliminate or reduce the content of dissolved and dispersed pollutants in the wastewater solution. one way that can be done to treat wastewater is by adsorption (alagha et al., 2020). adsorption is a physical method that is widely used to treat waste because it is easy, ecient, and can use various types of adsorbents (xu et al., 2021). one of the adsorbents that can be used to absorb dyes is layered double hydroxide (ldh) (zubair et al., 2018). ldh is a material consisting of a positively charged layer of 2-dimensional (2d) brucite. the presence of a network of hydrogen bonds between ldh layers results in the accumulation of layers, resulting in ldh in bulk form which has a 3-dimensional (3d) character. ldh has unique characteristics such as being easy to synthesize, having anions between layers that are easily exchanged, and having a large surface area (xu et al., 2021). ldh also has a positive total charge so it is often used as an adsorbent (benicio et al., 2015). ldh have the general formula: [m2+1-xm3+x(oh)2]x+(an-)x/n.nh2o where m2+ and m3+ are two and three valent metals, n is the mole fraction m3+/(m3++m2+) and a are balancing anions between layers (karami et al., 2019). the coprecipitation method can be used in the ldh synthesis process. the ratio used is 3:1 (m2+:m3+) because ldh is known as a hydrotalcite material. the eectiveness and eciency of the material are the basis for selecting the use of a particular material. besides the abundance of quality products, there is also a large buildup of chemical waste. the need to reuse and recycle materials such as composites is one of the best solutions. ldh has poor structural stability so it is necessary to modify ldh to produce composites. modication of ldh can be done using graphene (vinsiah et al., 2020), humic acid (li et al., 2020a), biochar (huangetal.,2019),hydrochar(jungetal.,2021), andchitosan (siregar et al., 2021a). chitosan is a derivative of chitin with the structure [𝛽(1→4)-2-amine-2-deoxy-d-glucose] (zeng et al., 2015). chitosan is a type of cationic polysaccharide biosorbent (zhang et al., 2020). ldh has a less than optimal ability in the absorption process of cationic species so it is necessary to modify ldh with chitosan. the advantages of chitosan such as having nh2 and oh functional groups that can help increase the absorption of cationic species because there will be interactions between the functional groups in chitosan and functional groups in cationic species such as methylene blue. siregar et al. (2021a) reported thatmg/al-chitosanwasable toadsorbcongo red dye with a maximum capacity of 344.828 mg/g. research conducted bykhalili et al. (2021) reported that mnfe/chitosan showed a non signicant decrease for four consecutive cycles of sunset yellow (sy) dye removal of 94.23%, 85.87%, 79.26%, and 61.98%, respectively. in this study, modication of ldh using chitosan aims to increase the surface area of the material so that the adsorption capacity obtained also increases, that the structure of the material is more stable so that it can be used repeatedly in the process of removing methylene blue dye in water. the synthesized materials were characterized using xrd, ftir, and bet analysis. in this study, the selectivity of a mixture of various dyes was carried out to determine the most selective dyestu. the most selective dyes for each adsorbent will be subjected to adsorption studies including kinetic, isotherms, and thermodynamics, as well as adsorbent regeneration studies. 2. experimental section 2.1 chemicals and instrumentation the materials used in this study were mg(no3)2.6h2o (emsure r), al(no3)3.9h2o (sigma-aldrich), chitosan extract ed from shrimp shells, naoh, distilled water, nitrogen, rhoda mine-b (rh-b), malachite green (mg), and methylene blue (mb). the synthesized material was characterized using xray rigaku miniex-6000, ftir by shimadzu prestige-21, and adsorption–desorption n2 analysis was performed using a quantachrome micromeritics asap surface area and porosity analyzer, as well as adsorption analysis using uv-visible bio-base spectrophotometer bk-uv1800. 2.2 synthesis of mg/al the coprecipitation method with molar ratio (3:1) was used in the synthesis of mg/al-no3 ldh. mg(no3)2.6h2o (19.230 g, 100 ml) and al(no3)3.9h2o (9.378 g, 100 ml) were mixed and the ph was adjusted to 10 using 2 m naoh. the mixture was stirred at 80°c for 17 hours and was used in atmospheric nitrogen conditions to minimize the formation of mg/al-co3 in the synthesis process. after 17 hours, the precipitate was ltered, rinsed, and dried. materials were characterized using xrd, ftir, and bet analysis. 2.3 extraction of chitosan demineralization and deproteination processes were carried out to extract shrimp shells. shrimp shells were crushed and put into a beaker, then 1 m hcl was added in a ratio of 1:10 (w/v). the mixture was stirred at 60°c for 3 hours. after the stirring is complete, the precipitate is ltered and dried. after the demineralization process is complete, it is followed by the deproteination process. the residue from the demineralization process was put into a beaker and 0.1 m naoh was added in a ratio of 1:10 (w/v). the mixture was stirred at 60°c for 1 hour. after 1 hour, the precipitate was ltered and dried in the oven. the chitosan obtained was characterized using xrd, ftir, and bet to prove the success of extracting chitosan from shrimp shells. 2.4 preparation of mg/al-chitosan 60mlofamixtureofmg(no3)2.6h2oandal(no3)3.9h2o solutions were stirred for 1 hour and the ph was adjusted to 10 using naoh. after 1 hour, 3 g of chitosan was added to the mixture. stirring was continued for up to 72 hours at 80°c. after completion, the precipitate was ltered, rinsed, and dried for characterization using xrd, ftir, and bet analysis. © 2022 the authors. page 171 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 2.5 selectivity dyes (rhodamine-b, malachite green, and methylene blue) 20 mg/l of each dye as much as 20 ml was added with 0.02 g of adsorbent. the mixture is stirred according to the predetermined contact variation. after the stirring was completed, the ltrate was measured at 500-700 nm using a uv-visible spectrophotometer. the dye with the largest adsorption capacity is used in the next adsorption process. 2.6 eect of adsorption contact time 100 mg/l methylene blue (20 ml, 0.02 g adsorbent) adjusted the ph according to the optimum ph of methylene blue. the mixture was stirred according to variations in contact time (0, 5, 20, 30, 60, 90, 120, 150, 180, and 200 minutes) and the ltrate was measured using a uv-visible spectrophotometer. 2.7 eect of concentration and temperature variations in the initial concentration of methylene blue and variations in adsorption temperature were carried out to see the eect of isotherm and adsorption thermodynamics. the initial concentration variations (60, 70, 80, 90, and 100 mg/l) were 20 ml and 0.02 g of adsorbent was added. the mixture was stirred for 2 hours and using various temperatures (30, 40, 50, and 60°c). after 2 hours, the ltrate was measured using a uv-visible spectrophotometer at a wavelength of methylene blue (664 nm). 2.8 regeneration of adsorbent the regeneration process was carried out by adsorption of mb dye (100 mg/l, 25 ml) and adding 0.1 g of adsorbent. the solution was stirred and the ltrate was measured using a uv-visible spectrophotometer. the adsorbate bound to the adsorbent will be released by a desorption process using an ultrasonic system, then the adsorbent is dried using an oven. the same treatment was carried out for the next cycle. 3. results and discussion figure 2(a) shows the diraction pattern of mg/al where peaks appear at angles 11.47°(003), 22.86°(006), 34.69°(009), and 61.62°(110), the results obtained are similar to jcpds data no. 22-700. figure 2(b) shows the diraction pattern of chitosan where peaks appear at an angle of 7.93°(003) and 19.35°(002) as reported by mohadi et al. (2022) that the diraction pattern of chitosan appears at an angle of 9.49°(001) and 19.59°(002). peaks that appear at angles 10.83°(003), 19.52°(006), and 60.6°(110) indicates that mg/al-chitosan has a characteristic peak from each of its constituent materials, namely ldh and chitosan. this indicates that the mg/al-chitosan synthesis process was successful (figure 2(c)). figure 3(a) shows the results of the ftir analysis of mg/al which appears at 3500 cm−1 indicatingoh vibrations from water molecules and at 1635 cm−1 stretching vibrations from oh occur. the n-o group from nitrate appears at a wavenumber of 1381 cm−1. the peak that appears at 748 cm−1 indicates the presence of m-o vibrations. figure 3(b) shows the spectrum figure 2. xrd patterns of mg/al (a), chitosan (b), and mg/al-chitosan (c) figure 3. ftir spectra for mg/al (a), chitosan (b), and mg/al-chitosan (c) of chitosan, where the strain vibrations of the nh2 and oh groups occur at 3447 cm−1. spectrums that appeared at 1652 cm−1 and 1566 cm−1 indicated the presence of conh2 and nh2 from chitosan. figure 3(c) shows the results of mg/alchitosan where the spectrum that appears at 1381 cm−1 is the vibration of the nitrate anion from ldh and the spectrum at 3447 cm−1 shows the strain of nh2 and oh groups from chitosan (mohadi et al., 2022). important factors aecting the quality of the adsorbent are surface area, pore volume, and pore size. analysis to determine surface area, pore volume, and pore size can be done using the bet method. bet theory is based on the adsorption process using the principle of adsorption isotherm (langmuir © 2022 the authors. page 172 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 table 1. bet analysis of materials materials surface area pore volume pore size (m2/g) (cm2/g) bjh (nm), bjh mg/al 5.845 0.017 17.057 chitosan 8.558 0.018 16.983 mg/al-chitosan 24.556 0.031 3.169 table 2. kinetic parameter adsorbent initial concentration qeexp pfo pso (mg/l) (mg/g) qecalc (mg/g) r 2 k1 qecalc (mg/g) r 2 k2 mg/al 100.608 40.919 10.044 0.901 0.032 41.322 0.999 0.012 chitosan 100.608 45.421 1.262 0.901 0.023 45.455 0.999 0.057 mg/alchitosan 100.608 46.877 2.757 0.922 0.037 46.948 0.999 0.029 figure 4. bet prole of mg/al (a), chitosan (b), and mg/al-chitosan (c) theory). in the adsorption process, the system that occurs is gassolid. gases are adsorbed (adsorbate) and solids are adsorbents (adsorbent). the pore size of the adsorbent will be determined bythe amount of gas absorbed. based on the results of the bet analysis, the data obtained are as shown in table 1. the surface area of mg/al is 5.845 m2/g, the surface area of chitosan is 8.558 m2/g, and the surface area of mg/al-chitosan has increased to 24.556 m2/g. figure 4 shows the adsorptiondesorption pattern of each adsorbent following type iv where the adsorption isotherm on mesoporous adsorbents with strong and weak anities (siregar et al., 2021b). figure 5 shows the selectivity of a mixture of rhodamine-b (rh-b), malachite green (mg), and methylene blue (mb) dyes. in figure 5, it can be seen that the longer the time used, the more signicant the decrease in absorbance for mb dye. at figure 5. selectivity of rh-b, mg, and mb onto mg/al (a), chitosan (b), and mg/al-chitosan (c) 90-120 minutes it shows that there is an insignicant decrease in mb, this indicates that at 90-120 minutes mb has been in equilibrium. figure 6 shows a graph of the eect of contact time on the adsorption of methylene blue by the adsorbent, where the longer the adsorption contact time, the greater the methylene blue adsorbed. the results showed that each adsorbent optimally adsorbed methylene blue at 90 minutes, but if it is too long it can reduce the absorption rate. the longer the contact time can also lead to desorption, namely the release of dye © 2022 the authors. page 173 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 table 3. isotherm adsorption adsorbent adsorption adsorption 303kisotherm constant mg/al langmuir qmax 84.746 kl 0.017 r2 0.7454 freundlich n 2.05 kf 13.527 r2 0.6056 chitosan langmuir qmax 89.286 kl 0.018 r2 0.9862 freundlich n 1.458 kf 7.525 r2 0.5047 mg/al-chitosan langmuir qmax 108.696 kl 0.36 r2 0.8959 freundlich n 2.181 kf 18.655 r2 0.6207 figure 6. variation of adsorption contact time that has been bound by the adsorbent. bernard and jimoh (2013) showed that after the adsorption reached equilibrium at the optimum contact time, the further addition of contact time between the adsorbent and the adsorbate did not have a signicant eect on the absorption of the dye. the determination of the equilibrium model depends on the value of the correlation coecient (r2). a suitable equilibrium model is an equilibrium model with a value of (r2) that is higher or closer to 1 (seedao et al., 2018; juleanti et al., 2021). the value of the correlation coecient (r2) of the secfigure 7. eect of initial concentration and adsorption temperature of mg/al (a), chitosan (b), and mg/al-chitosan (c) ond order is closer to one (1) than the rst order. if the value of (r2) in pseudo rst order (pfo) is greater and closer to the value of 1 then the adsorption involves a physical reaction and if the value of (r2) in the pseudo second order (pso) is greater and closer to the value of 1 then the adsorption involves © 2022 the authors. page 174 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 table 4. thermodynamic adsorption adsorbent t (k) qe δh δs δg (mg/g) (kj/mol) (j/mol k) (kj/mol) mg/al 303 41.416 16.487 0.061 -1.873 313 43.053 -2.479 323 45.237 -3.085 333 48.208 -3.691 chitosan 303 44.6 12.669 0.05 -2.558 313 45.843 -3.06 323 47.238 -3.563 333 49.36 -4.065 mg/al-chitosan 303 49.572 31.703 0.117 -3.694 313 51.756 -4.862 323 54.211 -6.03 333 56.394 -7.198 table 5. adsorption capacity using several adsorbents adsorbent adsorption referencecapacity (mg/g) chitosan/zeolite composite 24.51 (dehghani et al., 2017) h2so4 cross-linked magnetic 20.41 (rahmi and mustafa, 2019) chitosan nanocomposite beads fe3o4 activated montmorillonite 106.4 (chang et al., 2016) nanocomposite chitosan resin 11.3 (buaphean et al., 2017) chitosan 11.04 (moosa et al., 2016) activated lignin chitosan 36.25 (albadarin et al., 2017) n,o-carboxymethyl chitosan 1.14 (sulizi and mobarak, 2020) ultrasonic surface modied chitin 26.69 (dotto et al., 2015) carbon physical activation 15.553 (khuluk, 2019) dried cactus (dc) 14.045 (sakr et al., 2020) natural cactus (nc) 3.435 (sakr et al., 2020) chitosan/organic rectorite-fe3o4 24.69 (zeng et al., 2015) natural zeolite 21.189 (ngapa and gago, 2021) micro cellulose fibrils 54.9 (kankilic and metin, 2020) rice husk 25 (patil et al., 2017) mg/al 84.746 this work chitosan 89.286 this work mg/al-chitosan 108.696 this work a chemical reaction (wang et al., 2013). the adsorption rate data in table 2 shows that the pso model provides a more presentable model of the adsorption rate, the second-order equation is based on the assumption that adsorption involves a chemical process between the adsorbent and the adsorbate (hamzezadeh et al., 2022). the adsorption isotherm was determined to determine the relationship between the concentration of the adsorbed substance (adsorbate) and the amount absorbed at a constant temperature. there are two types of isotherms commonly used to determine the type of adsorption, namely the langmuir isotherm and the freundlich isotherm (seedao et al., 2018). the determination of the langmuir isotherm is done by making a relationship curve between ce and ce/qe, so that the ce versus ce/qe curve is obtained. while the determination of the freundlich isotherm is done by making a curve of the relationship between log ce and log qe (amtul et al., 2018). figure 7 shows a linearization graph for the adsorption of each adsorbent on methylene blue. this is indicated by the value of the linear regression coecient (r2) on the langmuir © 2022 the authors. page 175 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 isotherm is greater than the freundlich isotherm so that the adsorption pattern that occurs on each adsorbent with methylene blue dye is monolayer with the langmuir isotherm model (zhang et al., 2020). the adsorption capacities of mg/al, chitosan, and mg/al-chitosan were 84.7466 mg/g, 89.286 mg/g, and 108.696 mg/g as shown in table 3. the results showed that mg/al-chitosan was the most eective adsorbent to absorb mb. figure 8. regeneration of mg/al (a), chitosan (b), and mg/al-chitosan (c) figure 9. adsorption mechanism of methylene blue using mg/al-chitosan thermodynamic parameters are needed to provide information related to the direction and changes in internal energy that occur during the adsorption process of methylene blue with the adsorbent including the enthalpy change (δh) (ge and du, 2020), the entropy change (δs) (ali et al., 2020), and the gibbs free energy change (δg) (zhu et al., 2012; mohadi et al., 2022). based on table 4, it can be seen that the energy released during the methylene blue adsorption process is highly dependent on the type of adsorbent interaction. the positive enthalpy parameter value (δh) stated in table 4 indicates that the adsorption process of methylene blue occurs endothermic where the adsorption capacity at the same initial concentration increases with increasing temperature (li et al., 2020b). the small entropy value (δs) indicates that the distribution of methylene blue on the adsorbent surface is very regular with a small entropy value (patil et al., 2017). the value of gibbs free energy (δg) is negative, indicating that the adsorption process of methylene blue takes place spontaneously (wang et al., 2013). the regeneration process of the adsorbent aims to see the ability to reuse the adsorbent which will be used for the readsorption process. regeneration aims to restore the function of the active site of the adsorbent so that it can bind the adsorbate again and there is a rearrangement of the groups of the adsorbent that have been used in the adsorption process. figure 8 shows that mg/al and chitosan decreased drastically from cycles 3-5, while mg/al-chitosan showed an insignicant decrease in adsorption capacity from cycles 1 to 5. this indicates that mg/al-chitosan is an eective adsorbent used repeatedly in the process of removing mb dye from water. theadsorptionmechanismofmethyleneblueusingmg/alchitosan is shown in figure 9. figure 9 shows the presence of functional groups of chitosan in the form of nh2 and oh bonded to methylene blue, thus the dye tends to bind more strongly to the oh group of chitosan, so that the binding of methylene blue on the adsorbent is more dominant in chemical adsorption, which is supported by the data. adsorption isotherm. a comparison of the adsorption capacity of methylene blue using various adsorbents is shown in table 5. table 5 shows that mg/al-chitosan in this study was able to adsorb methylene blue with the largest capacity compared to others, namely 108.696 mg/g. 4. conclusion this study aims to modify the ldh using chitosan, as evidenced by xrd analysis where the peaks that appear in mg/alchitosan are similar to the typical peaks of the constituent materials, namely mg/al and chitosan. this is conrmed by ftir analysis where the spectrum that appears in mg/al-chitosan is similar to the spectrum in mg/al and chitosan. as well as bet analysis where there is an increase in the surface area of mg/al after being modied to mg/al-chitosan from 5.845 m2/g to 24.556 m2/g. in the dye selectivity process, mb tends to be more easily absorbed than rh-b and mg. in this study, the adsorption process followed the langmuir isotherm equation. the thermodynamic data showed that the adsorption process was endothermic, regular, and spontaneous. the regeneration processconrmedthatmg/al-chitosan isaneectiveadsorbent for repeated use in the mb adsorption process. 5. acknowledgement all authors thanks to the laboratory of inorganic materials and complexes of the faculty of mathematics and natural sciences, sriwijaya university for support of this research. © 2022 the authors. page 176 of 178 siregar et. al. science and technology indonesia, 7 (2022) 170-178 references alagha, o., m. s. manzar, m. zubair, i. anil, n. d. mu’azu, and a. qureshi (2020). comparative adsorptive removal of phosphate and nitrate from wastewater using biocharmgal ldh nanocomposites: coexisting anions eect and mechanistic studies. nanomaterials, 10(2); 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46–54 zubair, m., n. jarrah, a. khalid, m. s. manzar, t. s. kazeem, and m. a. al-harthi (2018). starch nife layered double hydroxide composites: ecient removal of methyl orange from aqueous phase. journal of molecular liquids, 249; 254–264 © 2022 the authors. page 178 of 178 introduction experimental section chemicals and instrumentation synthesis of mg/al extraction of chitosan preparation of mg/al-chitosan selectivity dyes (rhodamine-b, malachite green, and methylene blue) effect of adsorption contact time effect of concentration and temperature regeneration of adsorbent results and discussion conclusion acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper enumerate the number of vertices labeled connected graph of order seven containing no parallel edges muslim ansori1, wamiliana1*, fitriani1, yudi antoni1, desiana putri1 1department of mathematics, faculty of mathematics and natural science, universitas lampung, bandarlampung, 35145, indonesia *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstracta graph that is connected g(v,e) is a graph in which there is at least one path connecting every two vertices in g; otherwise, it is calleda disconnected graph. labels or values can be assigned to the vertices or edges of a graph. a vertex-labeled graph is one in whichonly the vertices are labeled, and an edges-labeled graph is one in which only edges are assigned values or labels. if both verticesand edges are labeled, the graph is referred to as total labeling. if given n vertices and m edges, numerous graphs can be made,either connected or disconnected. this study will be discussed the number of disconnected vertices labeled graphs of order sevencontaining no parallel edges and may contain loops. the results show that number of vertices labeled connected graph of order seven with no parallel edges is n(g7,m,g)l= 6,727×cm6 ; while for 7≤g≤ 21, n(g7,m,g)l= kg c(m−(g−6))g−1 , where k7 =30,160, k8 = 30,765, k9=21,000, k10 =28,364, k11= 26,880, k12 =26,460 , k13 = 20,790, k14 =10,290, k15 = 8,022, k16 = 2,940, k17 =4,417, k18 = 2,835, k19 =210, k20 = 21, k21 = 1. keywordsvertex labeled, connected graph, order seven, loops received: 5 april 2022, accepted: 13 july 2022 https://doi.org/10.26554/sti.2022.7.3.392-399 1. introduction without any doubt, one of the most widely used elds of mathematics is graph theory, especially to represent a real-life problem because of the exibility of drawing a graph. the date of birth of graph theory began with the publication of euler’s solution regarding the konigsberg problem in 1736, one of the mathematical elds with specic birth date is graph theory (vasudev, 2006). given a set v={v1, v2, · · · , vn} of vertices/nodes, v≠∅, and a set of edges e={ei j|i,j𝜖v}, a graph g(v,e) is a structure that consists of ordered pair of v and e. in real-life problems, the cities, buildings, airports, and others can be portrayed by vertices, while the roads that connect the cities, the pipes that connect the buildings, the ight paths that connect the airports, and others can be portrayed by edges. in order to represent real-life problems, on the edges, we can assign nonstructural information such as distance, time, ow, cost, and others by setting a non-negative number ci j≥0. there is a lot of application of graph theory in real-life problems, such as in computer science, chemistry, biology, sociology, agriculture, and others. in computer science, the graph structure plays an important role, for example, in designing a database, software engineering, and network system (singh, 2014). the database is used for interconnecting analysis, as a storage system with index-free adjacency, as a tool for graphlike-query, and for other purposes. in network design, graphbased representation makes the problem easier to visualize and provides a more accurate denition. in agriculture, the dynamic closures of the accounting structure are represented by a directed graph (álvarez and ehnts, 2015). the structure of graphs, together with discrete mathematics, are applied in chemistry to model the biological and physical properties of chemical compounds (burch, 2019). the theoretical graph concept also was used by gramatica et al. (2014) to represent or describe the possible modes of action of a given pharmacological compound. in biology, a phylogenetic tree was represented by a leaf-labeled tree (huson and bryant, 2006; brandes and cornelsen, 2009), while mathur and adlakha (2016) represented dna using a combined tree. hsu and lin (2008) presented many graph theoretical concepts in engineering and computer science, and al etaiwi (2014) used the concepts of a complete graph, cycle graph, and minimum spanning tree to generate a complex cipher text. priyadarsini (2015) explored the use of graph theory concepts, expander, and extremal graphs, in the design of some ciphers, whereas ni et al. (2021) created ciphers using corona and bipartite graphs. in agriculture, graph theory concepts were used to https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.392-399&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.392-399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 group agricultural workers performing manual tasks (kawakura and shibasaki, 2018), while the concept of graph coloring to optimize a farmer’s goal was used by kannimuthu et al. (2020). the relationship and unication of graph theory and physicalchemical measures (such as boiling and melting point, covalent and ionic potentials, and electronic density) make molecular topology can describe molecular structure comprehensively. a weighted directed graph, connectivity matrix, and dijkstra’s algorithm were used by holmes et al. (2021) in plasma chemical reaction engineering. the basic structure of a directed graph is mostly used for the visualization of the reactions. moreover, they use gelphi, an open-source graph software for visualization. in 1874, cayley counted the number of hydrocarbon isomers cnh2n+2 (cayley, 1874), and this process is similar to enumerating the number of a binary tree. bona (2007) discussed the method of enumerating trees and forests. redeld and pólya are two other mathematicians that worked independently with graphical enumeration, especially in graph coloring (bogart, 2004), and in graph enumeration, a comprehensive explanation of pólya’s counting theorem is one of the most powerful tools. the number of graphs that can be formed for labeled and unlabeled graphs is dierent if we are given n vertices and m edges. for example, given n= 3 and m= 2, the number of simple connected unlabeled graphs that can be constructed is only one, while if every vertex is assigned labeled, the maximum number of graphs that can be created is three. the higher the order of the graph, the more labeled graph are formed. agnarsson and greenlaw (2006) gave the formula to enumerate graphs. however, no formula for enumerating graphs with special properties such as planarity or connectivity was provided. there are some studies that have been done concerning the enumeration of the vertex-labeled graph with connectivity properties. in 2017, amanto et al. (2017) proposed the formula to count disconnected vertices labeled graphs of order maximal four. for order ve, the number of labeled vertices in connected graphs with no loops and may contain maximal ve parallel edges had been proposed by wamiliana et al. (2019). amanto et al. (2021) studied the relationship between the formula for the number of connected vertex labels with no loops in graphs of order ve and order six. wamiliana et al. (2020) also discussed the number of vertices labeled connected graphs of order six with no parallel edges and a maximum of ten loops, while puri et al. (2021) gave the formula to compute the number of vertices labeled connected graphs of order six without loops, while ansori et al. (2021) proposed the number of vertices labeled connected graphs of order seven with no loops. the article is organized as follows: section i provides information about graphs, graph applications in various elds, and previous research related to this topic. section ii discusses observation and investigation, while section iii discusses results and discussion. section iv contains the conclusion. 2. observation and investigation suppose that we are given the number of vertices n= 7, and the number of edges m. we will construct connected graphs g(v,e) of order n. since the graph must be connected, then m≥6. moreover, every vertex is labeled. let g as the number of non-loop edges, g≥n–1. we start rstly by constructing all basic patterns of connected graphs of order seven. note that the basic patterns contain no loops. the basic pattern starts with m= 6, and with n= 7, m= 6, and constructs all possible patterns. after all possible patterns for m= 6 are already constructed, then we continue with m= 7, and so on until m= 21. when m= 21, only one pattern can be constructed because parallel edges are not allowed. figure 1 shows some examples of patterns for m= 6, figure 2 shows some patterns that are isomorphic with the rst graph in the second row of the graphs in figure 1, and figure 3 shows when m= 21. figure 1. some basic patterns for n= 7 and m= 6 note that all isomorphic graphs will be counted in the pattern. however, we do not need to construct isomorphic graphs. figure 2 shows the patterns of isomorphic graphs of the pattern of the rst graph in the second row of figure 1. figure 2. some patterns are isomorphic with the first graph in the second row in figure 1 figure 3. the basic pattern for n= 7 and m= 21 © 2022 the authors. page 393 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 figure 4. the procedure after constructing the basic pattern, the enumeration step begins. it begins from the rst pattern of n= 7 dan m= 6 by adding one loop so that m= 7, calculating the number of graphs thatareable tobeformed, andthencontinuingwith thispattern by increasing the number of loops (m= 9), and so on. continue with this similar manner until the last pattern. the procedure can be put in the following diagram: 3. results and discussion the rst step, as given in figure 4 is constructing all possible patterns. because there are many patterns obtained and due to limitation of space, here we give some patterns and also the number of all possible graphs formed according to the patterns. the obtained graphs are grouped by m and g, for example, for n=6, m= 6, and g= 6, the patterns are: the results for all patterns are shown in table 1 below: please note that in the table the dash sign (−) means there is impossible to construct the graph, while the empty space on the table means that we are not calculate more because g is xed in each column, adding more edges simply adds more loops, and the constructed graph already constitute a sequence of numbers. the number in each column is able to be written as multiplication of a x number and a sequence of number so that table 2 can be rewritten in table 3 as follow: from table 3 we can see that for every g= 6, 7, · · · , 21, the number of graphs obtained are bigger as m increases, and the number of graphs obtained are multiplication of a x number. for example, for g= 6, the x number is 6,727, and the number of graphs increases follows a certain pattens of sequence which is 1, 7, 28, 84, 210, 462, 924, 1,716, 3,003, 5,005. 1 7 28 84 210 462 924 1716 3003 5005 6 21 56 126 252 462 792 1287 2002 15 35 70 126 210 330 495 715 table 1. the pattern for n= 7, m= 6, and g= 6 the patterns the number of isomorphic graphs c71.c 6 6= 7 7! 2 = 2,520 c71.c 6 3.c 3 2= 420 c71.c 6 2.c 4 3.1= 420 c71.c 6 3.3!= 840 c71.c 6 1.c 5 2.c 3 3= 420 c71.c 6 1.c 5 1.c 4 4= 210 c72.c 5 1.c 4 2.2!= 1,260 c72.c 5 1.c 4 2.c 2 2= 630 total 6,727 © 2022 the authors. page 394 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 table 2. the number of vertices labeled connected graph of order seven containing no parallel edges the number of vertices labeled connected order seven graphs with no parallel edges m g 6 7 8 9 10 11 6 6,727 − − − − − 7 47,089 30,160 − − − − 8 188,356 211,120 30,765 − − − 9 565,068 844,480 215,355 21,000 − − 10 1,412,670 2,533,440 861,420 147,000 28,364 − 11 3,107,874 6,333,600 2,584,260 588,000 198,548 26,880 12 6,215,748 13,933,920 6,460,650 1,764,000 794,192 188,160 13 11,543,532 27,867,840 14,213,430 4,410,000 2,382,576 752,640 14 20,201,181 51,754,560 28,426,860 9,702,000 5,956,440 2,257,920 15 33,668,635 90,570,480 52,792,740 19,404,000 13,104,168 5,644,800 16 − 150,950,800 92,387,295 36,036,000 26,208,336 12,418,560 17 − − 153,978,825 63,063,000 48,672,624 24,837,120 18 − − − 105,105,000 85,177,092 46,126,080 19 − − − − 141,961,820 80,720,640 20 − − − − − 134,534,400 the number of vertices labeled connected order seven graphs with no parallel edges m g 12 13 14 15 16 12 26,460 − − − − 13 185,220 20,790 − − − 14 740,880 145,530 10,290 − − 15 2,222,640 582,120 72,030 8,022 − 16 5,556,600 1,746,360 288,120 56,154 2,940 17 12,224,520 4,365,900 864,360 224,616 20,580 18 24,449,040 9,604,980 2,160,900 673,848 82,320 19 45,405,360 19,209,960 4,753,980 1,684,620 246,960 20 79,459,380 35,675,640 9,507,960 3,706,164 617,400 21 132,432,300 62,432,370 17,657,640 7,412,328 1,358,280 22 − 104,053,950 30,900,870 13,765,752 2,716,560 23 − − 51,501,450 24,090,066 5,045,040 24 − − − 40,150,110 8,828,820 25 − − − − 14,714,700 the number of vertices labeled connected order seven graphs with no parallel edges m g 12 13 14 15 16 17 4,417 − − − − 18 30,919 2,835 − − − 19 123,676 19,845 210 − − 20 371,028 79,380 1,470 21 − 21 927,570 238,140 5,880 147 1 22 2,040,654 595,350 17,640 588 7 23 4,081,308 1,309,770 44,100 1,764 28 24 7,579,572 2,619,540 97,020 4,410 84 25 13,264,251 4,864,860 194,040 97,02 210 26 22,107,085 8,513,505 360,360 19,404 462 27 − 14,189,175 630,630 36,036 924 28 − − 1,051,050 63,063 1,716 29 − − − 105,105 3,003 30 − − − − 5,005 © 2022 the authors. page 395 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 table 3. alternative form of table 2 the number of vertices labeled connected order seven graphs with no parallel edges m g 6 7 8 9 10 11 6 1x6,727 − − − − − 7 7x6,727 1x30,160 − − − − 8 28x6,727 7x30,160 1x30,765 − − − 9 84x6,727 28x30,160 7x30,765 1x21,000 − − 10 210x6,727 84x30,160 28x30,765 7x21,000 1x28,364 − 11 462x6,727 210x30,160 84x30,765 28x21,000 7x28,364 1x26,880 12 924x6,727 462x30,160 210x30,765 84x21,000 28x28,364 7x26,880 13 1,716x6,727 924x30,160 462x30,765 210x21,000 84x28,364 28x26,880 14 3,003x6,727 1,716x30,160 924x30,765 462x21,000 210x28,364 84x26,880 15 5,005x6,727 3,003x30,160 1,716x30,765 924x21,000 462x28,364 210x26,880 16 − 5,005x30,160 3,003x30,765 1,716x21,000 924x28,364 462x26,880 17 − − 5,005x30,765 3,003x21,000 1,716x28,364 924x26,880 18 − − − 5,005x21,000 3,003x28,364 1,716x26,880 19 − − − − 5,005x28,364 3,003x26,880 20 − − − − − 5,005x26,880 the number of vertices labeled connected order seven graphs with no parallel edges m g 12 13 14 15 16 12 1x26,460 − − − − 13 7x26,460 1x20,790 − − − 14 28x26,460 7x20,790 1x10,290 − − 15 84x26,460 28x20,790 7x10,290 1x8022 − 16 210x26,460 84x20,790 18x10,290 7x8,022 1x2,940 17 462x26,460 210x20,790 84x10,290 28x8,022 7x2,940 18 924x26,460 462x20,790 210x10,290 84x8,022 28x2,940 19 1,716x26,460 924x20,790 462x10,290 210x8,022 84x2,940 20 3,003x26,460 1,716x20,790 924x10,290 462x8,022 210x2,940 21 5,005x26,460 3,003x20,790 1,716x10,290 924x8,022 462x2,940 22 − 5,005x20,790 3,003x10,290 1,716x8,022 924x2,940 23 − − 5,005x10,290 3,003x8,022 1,716x2,940 24 − − − 5,005x8,022 3,003x2,940 25 − − − − 5,005x2,940 the number of vertices labeled connected order seven graphs with no parallel edges m g 12 13 14 15 16 17 1x4,417 − − − − 18 7x4,417 1x2,835 − − − 19 28x4,417 7x2,835 1x210 − − 20 84x4,417 28x2,835 7x210 1x21 − 21 210x4,417 84x2,835 28x210 7x21 1x1 22 462x4,417 210x2,835 84x210 28x21 7x1 23 924x4,417 462x2,835 210x210 84x21 28x1 24 1,716x4,417 924x2,835 462x210 210x21 84x1 25 3,003x4,417 1,716x2,835 924x210 462x21 210x1 26 5,005x4,417 3,003x2,835 1,716x210 924x21 462x1 27 − 5,005x2,835 3,003x210 1,716x21 924x1 28 − − 5,005x210 3,003x21 1,716x1 29 − − − 5,005x21 3,003x1 30 − − − − 5,005x1 © 2022 the authors. page 396 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 20 35 56 84 120 165 220 15 21 28 36 45 55 6 7 8 9 10 1 1 1 1 notate n(g7,m,g)l as the number of vertices labeled connectedgraphsofordersevencontainingnoparallel edges (loops are allowable) with the number of edges is m and the number of non loop edges is g. result 1: given m≥6, g= 6, the total number of vertices labeled connected graphs of order seven with no parallel edges is n(g7,m,g)l= 6,727×cm6 proof: consider the above sequence of numbers. that sequence of numbers is able to be represented by polynomial of order six because the xed q5m = 𝛼6m 6 + 𝛼5m5 + 𝛼4m4 + 𝛼3m3 + 𝛼2m2 + 𝛼1m + 𝛼0 the following system of equations is obtained by substituting m= 6, 7, 8, 9, 10, 11, 12 to q5(m). 6, 727 = 46, 656𝛼6 + 7, 776𝛼5 + 1, 296𝛼4 + 216𝛼3 + 36𝛼2 + 6𝛼1 + 𝛼0 (1) 47, 089 = 117, 649𝛼6 + 16, 807𝛼5 + 2, 401𝛼4 + 343𝛼3 + 49𝛼2 + 7𝛼1 + 𝛼0 (2) 188, 356 = 262, 144𝛼6 + 32, 768𝛼5 + 4, 096𝛼4 + 512𝛼3 + 64𝛼2 + 8𝛼1 + 𝛼0 (3) 565, 068 = 531, 441𝛼6 + 59, 049𝛼5 + 6, 561𝛼4 + 729𝛼3 + 81𝛼2 + 9𝛼1 + 𝛼0 (4) 1, 412, 670 = 1, 000, 000𝛼6 + 100, 000𝛼5 + 10, 000𝛼4 + 1, 000𝛼3 + 100𝛼2 + 10𝛼1 + 𝛼0 (5) 3, 107, 874 = 1, 771, 561𝛼6 + 161, 051𝛼5 + 14, 641𝛼4 + 1, 331𝛼3 + 121𝛼2 + 11𝛼1 + 𝛼0 (6) 6, 215, 748 = 2, 985, 984𝛼6 + 248, 832𝛼5 + 20, 736𝛼4 + 1, 728𝛼3 + 144𝛼2 + 12𝛼1 + 𝛼0 (7) these equations form a system of equations that can be transformed into a matrix ax= b as follow:  46, 656 7, 776 1, 296 216 36 6 1 117, 649 16, 807 2, 401 343 49 7 1 262, 144 32, 768 4, 096 512 64 8 1 531, 441 59, 049 6, 561 729 81 9 1 1, 000, 000 100, 000 10, 000 1, 000 100 10 1 1, 771, 561 161, 051 14, 641 1, 331 121 11 1 2, 985, 984 248, 832 20, 736 1, 728 144 12 1   𝛼6 𝛼5 𝛼4 𝛼3 𝛼2 𝛼1 𝛼0  =  6, 727 47, 089 188, 356 565, 068 1, 412, 670 3, 107, 874 6, 215, 748  by solving this system of equations we get: 𝛼6= 6,727 720 , 𝛼5= −100,905720 , 𝛼4= 57,175 720 , 𝛼3= − 151,575 720 , 𝛼2= 1,843,198 720 , 𝛼1= −807,240720 , 𝛼0= 0. thus q5(m) =𝛼6m6 + 𝛼5m5 + 𝛼4m4 + 𝛼3m3 + 𝛼2m2 + 𝛼1m+𝛼0 = 6, 727 720 m6 − 100, 905 720 m5 + 57, 175 720 m4 − 151, 575 720 m3 + 1, 843, 198 720 m2 − 807, 240 720 m = 6, 727 720 (m6 − 15m5 + 85m4 − 225m3 + 274m2 − 120m) = 6, 727(m − 1) (m − 2) (m − 3) (m − 4) (m − 5) (m − 6)! 6.5.4.3.2.1(m − 6)! =6, 727 × cm6 please note that for every g (every column, the sequence of numbers is the same, except the multiplier). thus, the polynomial related to the sequence of numbers is the same. however, because the multipliers are dierent, it will cause dierent formulas. result 2: given m≥7, g= 7, the total number of vertices labeled connected graphs of order seven with no parallel edges is n(g7,m,g)l= 30,160×c (m−1) 6 proof: the polynomial that represents the sequence is the same which is q5m = 𝛼6m 6 + 𝛼5m5 + 𝛼4m4 + 𝛼3m3 + 𝛼2m2 + 𝛼1m + 𝛼0 however, for m= 7, the numbers of graphs are dierent. the following system of equations is obtained by substituting m= 7, 8, 9, 10, 11, 12, 13 to the equation. 30, 160 = 117, 649𝛼6 + 16, 807𝛼5 + 2, 401𝛼4 + 343𝛼3 + 49𝛼2 + 7𝛼1 + 𝛼0 (8) 211, 120 = 262, 144𝛼6 + 32, 768𝛼5 + 4, 096𝛼4 + 512𝛼3 + 64𝛼2 + 8𝛼1 + 𝛼0 (9) 844, 480 = 531, 441𝛼6 + 59, 049𝛼5 + 6, 561𝛼4 + 729𝛼3 + 81𝛼2 + 9𝛼1 + 𝛼0 (10) 2, 533, 440 = 1, 000, 000𝛼6 + 100, 000𝛼5 + 10, 000𝛼4 + 1, 000𝛼3 + 100𝛼2 + 10𝛼1 + 𝛼0 (11) 6, 333, 600 = 1, 771, 561𝛼6 + 161, 051𝛼5 + 14, 641𝛼4 + 1, 331𝛼3 + 121𝛼2 + 11𝛼1 + 𝛼0 (12) 13, 933, 920 = 2, 985, 984𝛼6 + 248, 832𝛼5 + 20, 736𝛼4 + 1, 728𝛼3 + 144𝛼2 + 12𝛼1 + 𝛼0 (13) 27, 867, 840 = 4, 826, 809𝛼6 + 371, 293𝛼5 + 28, 561𝛼4 + 2, 197𝛼3 + 169𝛼2 + 13𝛼1 + 𝛼0 (14) these equations form a system of equations that can be transformed into a matrix ax= b as follow: 117, 649 16, 80 2401 343 49 7 1 262, 144 32, 768 4096 512 64 8 1 531, 441 59, 049 6561 729 81 9 1 1, 000, 000 100, 000 10, 000 1000 100 10 1 1, 771, 561 161, 051 14, 641 1331 121 11 1 2, 985, 984 248, 832 20, 736 1728 144 12 1 4, 826, 809 371, 293 28, 561 2197 169 13 1   𝛼6 𝛼5 𝛼4 𝛼3 𝛼2 𝛼1 𝛼0  =  30, 160 211, 120 844, 480 2, 533, 440 6, 333, 600 13, 933, 920 27, 867, 840  by solving this system of equations we get: 𝛼6= 30,160 720 , 𝛼5= −633,360720 , 𝛼4= 5,278,000 720 , 𝛼3= − 22,167,600 720 , 𝛼2= 48,979,840 720 , 𝛼1= −53,202,240720 , and 𝛼0= 21,715,200 720 . thus q5(m) =𝛼6m6 + 𝛼5m5 + 𝛼4m4 + 𝛼3m3 + 𝛼2m2 + 𝛼1m+𝛼0 = 30, 160 720 m6 − 633, 360 720 m5 + 5, 278, 000 720 m4 − 22, 167, 600 720 m3 + 48, 979, 840 720 m2 − 53, 202, 240 720 m + 21, 715, 200 720 = 30, 160 720 (m6 − 21m5 + 175m4 − 735m3 + 624m2 − 1764m + 720) = 30, 160 720 (m − 1) (m − 2) (m − 3) (m − 4) (m − 5) (m − 6) = 30, 160(m − 1) (m − 2) (m − 3) (m − 4) (m − 5) (m − 6) (m − 7)! 6.5.4.3.2.1(m − 7)! =30, 160 × c (m−1)6 the following results are obtained by doing the similar manner: for m≥8, g=8, is n(g7,m,g)l = 30,765×c (m−2) 7 for m≥9, g=9, is n(g7,m,g)l = 21,000×c (m−3) 8 for m≥10, g=10, is n(g7,m,g)l = 28,364×c (m−4) 9 for m≥11, g=11, is n(g7,m,g)l = 26,880×c (m−5) 10 for m≥12, g=12, is n(g7,m,g)l = 26,460×c (m−6) 11 for m≥13, g=13, is n(g7,m,g)l = 20,790×c (m−7) 12 for m≥14, g=14, is n(g7,m,g)l = 10,290×c (m−8) 13 © 2022 the authors. page 397 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 for m≥15, g=15, is n(g7,m,g)l = 8,022×c (m−9) 14 for m≥16, g=16, is n(g7,m,g)l = 2,940×c (m−10) 15 for m≥17, g=17, is n(g7,m,g)l = 4,417×c (m−11) 16 for m≥18, g=18, is n(g7,m,g)l = 2,835×c (m−12) 17 for m≥19, g=19, is n(g7,m,g)l = 210×c (m−13) 18 for m≥20, g=20, is n(g7,m,g)l = 21×c (m−14) 19 for m≥21, g=21, is n(g7,m,g)l = c (m−15) 20 note that themultiplierforg=6is thesameas themultiplier of t= 6 in ansori et al. (2021), as well as g=7 with t= 7, and so on until g=21 with t=21. however, the formulas are dierent because in ansori et al. (2021) the formula are for connected vertex labeled graph without loops while in this study is for connected vertices labeled graph without parallel edges. for example, for g=8, n(g7,m,g)l = 30,765×c (m−2) 7 , while in ansori et al. (2021), for t= 8, n(g7,m,8) = 30,765×c (m−1) 7 . 4. conclusions based on the above reasoning, we may conclude that the number of vertices in a labeled connected graph of order seven with no parallel edges is n(g7,m,g)l= 6,727×cm6 for g= 6, while for 7≤g≤ 21, n(g7,m,g)l= kg c (m−(g−6)) g−1 , where k7 =30,160, k8 = 30,765, k9 =21,000, k10 =28,364, k11= 26,880, k12 =26,460 , k13 = 20,790, k14 =10,290, k15 = 8,022, k16 = 2,940, k17 =4,417, k18 = 2,835, k19 = 210, k20 = 21, k21 = 1. 5. acknowledgment the research center universitas lampung funded this study under postgraduate research grant project no. 815/un26. 21/pn/2022, and the authors gratefully acknowledge the funding. references agnarsson, g.andr.greenlaw(2006). graphtheory: modeling, applications, and algorithms. prentice-hall, inc. al etaiwi, w. m. 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(2006). graph theory with applications. new age © 2022 the authors. page 398 of 399 ansori et. al. science and technology indonesia, 7 (2022) 392-399 international wamiliana, w., a. amanto, m. usman, m. ansori, and f. c. puri (2020). enumerating the number of connected vertices labeled graph of ordersixwith maximum ten loops and containing no parallel edges. science and technology indonesia, 5(4); 131–135 wamiliana, w., a. nuryaman, a. sutrisno, and n. prayoga (2019). determining the number of connected vertices labelled graph of order five with maximum number of parallel edges is five and containing no loops. journal of physics: conference series, 1338; 012043 © 2022 the authors. page 399 of 399 introduction observation and investigation results and discussion conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper the diameter and maximum link of the minimum routing cost spanning tree problem reni permata sari1,2, wamiliana3*, akmal junaidi4, wiwin susanty5 1postgraduate program, faculty of mathematics and natural sciences, universitas lampung, 35145, indonesia2faculty of science and technology, universitas nahdatul ulama, lampung, 34192, indonesia3department of mathematics, faculty of mathematics and natural sciences, universitas lampung, lampung, 35145, indonesia4department of computer science, faculty of mathematics and natural sciences, universitas lampung, lampung, 35145, indonesia5faculty of computer sciences, universitas bandar lampung, lampung, 35142, indonesia *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstractthe minimum routing cost spanning tree (mrcst) is a spanning tree that minimizes the sum of pairwise distances between itsvertices given a weighted graph. in this study, we use campos algorithm with slight modifications on the coefficient of spanningpotential. those algorithms were implemented on a random table problem data of complete graphs of order 10 to 100 in incrementsof 10. the goal is to find the diameter (the largest shortest path distance) and the maximum link (the maximum number of edgesconnecting two vertices) in the spanning tree solution of mrcst. the result shows that a slight modification of the spanning potentialcoefficients gives better solutions. keywordsdiameter, cost routing, campos algorithm, spanning potential, maximum link received: 12 july 2022, accepted: 11 october 2022 https://doi.org/10.26554/sti.2022.7.4.481-485 1. introduction one of the mathematical elds with specic birth dates is graph theory (vasudev, 2006). graph theory is a mathematical discipline that is used to represent discrete objects and the connections between these objects. a vertex can represent an object, while an edge can represent the relationship between objects. the graph theory concept was rst initiated by leonard euler in 1736 when he gave a solution to the konigsberg bridge problem in kaliningrad, russia. in the city of konigsberg, there is the pregel river which splits the city into four separate landmasses, and there are seven bridges that connect the landmasses as shown below: figure 1. illustration of konigsberg problem source: https://www.britannica.com/science/konigsbergbridge-problem the issue is that the people want to start from one of the landmasses, cross each bridge precisely once, and then return to the beginning. by representing the landmasses as nodes (vertices) and bridges as lines (edges), euler stated that this was impossible because the number of bridges connecting each landmass was odd. this problem is only possible if the number of bridges connecting each land is even. later, this model using vertices and edges representing lands and bridges became the background for the emergence of the current concept of graph theory. there is a rapid development of graph theory after the solution given by euler because of its exibility so that graph theory can be used to represent daily life problems. there are numerous applications of graph theory. for instance, in network-design problems such as transportation, power supply, water resource management, communication, and many others. in network design problems, some theoretical graph concepts are frequently used, such as shortest path (sp), minimum spanning tree (mst), and others. among the most popular concepts in graph theory is mst which is commonly used as a backbone in network design problems and has been extensively studied. kruskal (1956) introduced kruskal’s algorithms, and prim (1957) introduced prim’s algorithm to solve mst. those two algorithms are used extensively and are very famous. however, the rst algorithm https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.481-485&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.481-485 sari et. al. science and technology indonesia, 7 (2022) 481-485 to solve the mst was proposed by borŭvka (1926) when he solved the problem of constructing moravia’s power network in the czech republic. some fast algorithms have been proposed to solve mst due to its unique structure and application in numerous network design issues. the mst problem is commonly encountered in applications for network design where other graph parameters like distance, degree, diameter, ow, connectivity, and others must be satised. a distance constraint on commodity ow, for example, could represent the maximum delivery distance in a transportation network. the degree constrained minimum spanning tree (dcmst) is the problem of determining an mst whilst having to satisfy the degree restriction on each vertex. if, in addition to the degree constraint, there are additional constraints, namely the period, then the problem becomes a multi-stage network installation problem ormulti-period degree-constrained minimum spanning tree (mpdcmst) problem. in dcmst, all vertices can be connected without period restriction, while in mpdcmst there is a period restriction in connecting the vertices. the period restriction occurs because of some reasons, such as weather conditions, fund limitations, and so on. this problem was investigated by kawatra (2002) for implementation in a digraph, while wamiliana et al. (2015b); wamiliana et al. (2015a); wamiliana et al. (2020) implemented it in an undirected graph. given a connected weighted graph, the routing cost of the spanning tree is dened as the sum of the total path lengths of all pairs of vertices in the spanning tree of that graph. the mrcst aims to nd the lowest routing cost of the spanning tree. themrcstisalsoknownastheshortestaveragedistancespanning tree and in an unweighted graph is called the minimum wiener index. even though not as famous as traveling salesman problems where many researchers have been involved in that topic, some researchers have already investigated the mrcst problem, includingwu(2002); wolfandmerz(2010); chenetal. (2013); tan and due (2013); lin et al. (2006) and sattari and didehvar (2013). since the mrcst is an np-hard problem, then heuristic algorithms are investigated more, for example, singh (2008) and tan (2012b). singh and sundar (2011) investigated a bee colony algorithm, and hieu et al. (2011) proposed an ant colony algorithm. genetic algorithm for solving the mrcst problem has been investigated by tan (2012a); julstrom(2001) andjulstrom(2005). julstrom(2005) alsocoded the tree using blob code and showed that representing the tree using blob code in genetic algorithms performed better than coding the tree as an edge-set which was proposed by raidl and julstrom (2003). sattari and didehvar (2015) proposed a grasp with a metaheuristic path-relinking algorithm to solve mrcst. fischetti et al. (2002) showed that aside from network design, trees with low routing costs have found useful applications in biological computation, where they are applicable for nding good genomic sequence alignments. a heuristic that is based on the recognition of a network core around which it is possible to construct a solution was proposed by masone et al. (2019). in this study, we will discuss campos’s algorithm for mrcst because campos’s algorithm usually was used as a comparison for developed algorithms in the literature. in the next section, we will discuss the mrcst. 2. the problem given an undirected weighted connected graph g(v,e), v denotes the set of vertices. v= v1, v2, v3, · · · , vn, v≠∅, and e denote the collection of edges that connect the vertices in v, e={euv|(vu,vv)∈v}, and for each edge euv there is a corresponding weight cuv≥0, a minimum routing cost tree (mrct) t represents a spanning tree in such a way that for all spanning trees t that can be computed from g, cr(t*)= min ( ∑n u=1 ∑n v=1 ct(u,v), u≠v), where ct(u,v) is the cost of vertex u and vertex v,t* is thespanningtreewhose theminimalcost routingamong other spanning trees in g campos and ricardo (2008). cr(t) is the total cost of the shortest path for every pair of vertices in t where the shortest path is counted twice for every pair of vertices, once from vertex u to v, and once from v to u (routing). note that vertex u and v may be connected by a path, not by an edge. by dening d(u,v) as the distance of every pair (u,v) vertices in g, an mrcst can be described as a problem of determining the minimum total distance d(u,v) for each pair of vertices (u,v) in spanning tree t of g so that cr(t*)= ( ∑n u=1 ∑n v=1duv, u≠v), where t* is the spanning tree in g which produce the smallest total distance for each pair of vertices. in mrcst both d(u,v) and d(v,u) are take into account. to illustrate the problem, suppose that we are given a spanning tree of an undirected connected weighted graph as in figure 2. figure 2. spanning tree t to nd the total distance in a graph in figure 2, we calculate the distance for every pair of vertices in that spanning tree. let d(u,v) as the distance of vertex u and v, then d(v1,v2)= 7, d(v1,v3)= 27, d(v1, v4)= 22, d(v1,v5)= 20, d(v1,v6)= 15, d(v1,v7)= 4, d(v2,v3)= 20, d(v2,v4)= 15, d(v2,v5)= 13, d(v2,v6)= 8, d(v2,v7)= 3,d(v3,v4)=19,d(v3,v5)=17,d(v3,v6)=12,d(v3,v7)=23,d(v4,v5) =2,d(v4,v6)=7,d(v4,v7)=18,d(v5,v6)=5,d(v5,v7)=16,d(v6,v7)= 11. © 2022 the authors. page 482 of 485 sari et. al. science and technology indonesia, 7 (2022) 481-485 since in mrcst both d(u,v) and d(v,u) are under consideration, then the value of mrcst of the graph in example 1 is 2×(7+27+22+20+15+4+20+15+13+8+3+19+17+12+23+2+7+ 18+5+16+11)= 2×284= 568 a graph’s diameter is dened as the largest shortest path distance in the graph. it is, in other words, diameter is the maximum value of overall pairs, which denotes the shortest path distance from avertex to anothervertex. amaximal link is the numberof the maximal numberof edges that connect apair of vertices in a graph. for example, in figure 2, the diameter of that spanning tree t is 27 which is the distance between vertex v1 and v3, while the maximal link of that spanning tree is 5 which is the number of edges that connect vertex v1 and v4. for other pairs of vertices in that tree, the number of edges connecting them is less than 5. note that in a weighted spanning tree the diameter and the link of a spanning tree may not be the same, however, in an unweighted graph the diameter and the link are similar which is the maximal number of edges that connect a pair of vertices in the graph. 3. campos’ algorithm campos’algorithm begins bychoosing an initial vertexwith the criteria that the vertex has the largest spanning potential which is dened as: spv= c1 dv+c2 dv sv +c3 1 mv , where dv is the degree of vertex v, sv is the sum of the weight edges that incidence to v, and mv is the maximum weight of incidence edges, and c1, c2, and c3 are coecients. suppose v is the vertex with the largest spanning potential, then calculate wv, all the weight of incidence edges to v, pdv as the degree of the candidate parent vertex in t, psv as the sum of the adjacent edge weights of the candidate parent vertex in t, cfv as cost estimation for the path between vertex v and f in t. next, calculate parameters: wdv, jspv, sdv and swv as follow: wdv= c4 wv+c5 cfv (set c4= c5= 1), jspv: sdv+ sdv swv , sdv=dv+ pdv and swv=sv+psv. next step is make list l = {wv, dv, sv, pv, pdv, psv, cfv, wdv, jspv}, and put in v to l. l= {v, wv, dv, sv, pv, pdv, psv, cfv, wdv, jspv}. choose the highest value of wdv and jspv. if there is no value of wdv and jspv, remove all wv, dv, sv, pv, pdv, psv, cfv, wdv which relate to v and choose another vertex adjacent to v, and calculate again the parameter and continue the process as before. if wdv and jspv have values, then put v as the initial vertex and the smallest adjacent edge to v put into t. remove all parameters related to the current chosen edge and vertex. next, choose the smallest edge incidence with vertices in t and check if the addition of that edge in t constitutes a cycle. if yes, remove that edge, and choose the next smallest. if not, check if the spanning tree has already been obtained (|t| = n-1). if yes, stop, spanning tree t is obtained, otherwise, put in the chosen edge in l and repeat the process. 4. result and discusssion we run campos’s algorithm and slight modications on the coecient of spanning potential of campos’ algorithm on the data set problems which are complete weighted graphs of order 10 to 100 in increments of 10. the edge weights are integers generated at random from a uniform distribution (1, 1000), and 30 random problems are generated for each order. the algorithm is implemented using three dierent coecients of spanning potential. based on the simulation, we nd that the value of mrcst is smaller if the value of c2 is between 0.8 and 0.89. if the value of c2 is smaller than 0.8 or bigger than 0.89, the value of mrcst is bigger than the value of c2 recommended by campos and ricardo (2008) which is 0.6. based on implementation we get the following result: figure 3. spanning tree of n=10 for problem dat.10 using c1 = 0.2, c2 = 0.6 and c3= 0.2, and the value of mrcst is 22,745, with maximal link 6 and diameter 1034 figure 4. spanning tree of n=10 for problem dat.10 using c1= 0.1, c2= 0.8 and c3= 0.1, and the value of mrcst is 21,642, with maximal link 5 and diameter 1087 the coecient of c1= 0.2, c2= 0.6, and c3= 0.2 are suggested as the best coecients by campos and ricardo (2008), c1= 0.01, c2= 0.8, c3= 0.1 and c1= 0.1, c2= 0.89, and c3= 0.2 are two combinations of coecients to determine the value of spanning potential. from the simulation, we found that those two combinations are the best. from the result, we found that the highest number of edges connecting a pair of vertices is the same for all three variations. the smallest number occurs © 2022 the authors. page 483 of 485 sari et. al. science and technology indonesia, 7 (2022) 481-485 table 1. the results of implementation on complete graphs with order 10 to 100 in increments of 10 c1=0.2, c2= 0.6, c3= 0.2 c1= 0.02, c2= 0.89, c3= 0.1 c1= 0.1, c2= 0.8, c3= 0.1 n the average value of mrct the max link the largest diameter the average of the largest diameter the average value of mrct the max link the largest diameter the average of the largest diameter the average value of mrct the max link the largest diameter the average of the largest diameter 10 15,228.7 8 1429 770.8 15,179.3 8 1429 771.27 15,179.3 8 1429 771.27 20 44,262.4 12 799 551.1 44,119.13 11 799 542.2 44,119.13 11 799 542.2 30 75,626.03 14 573 429.5 75,581.5 14 573 429.5 75,581.5 14 573 429.5 40 113,285.2 17 478 354.97 113,285.2 17 478 354.97 113,285.2 17 478 354.97 50 167,045.8 16 427 318.133 166,982.1 16 427 319.23 166,982.07 16 427 319.23 60 200,377.4 21 364 274.67 200,381.4 21 364 275.2 200,381.4 21 364 275.2 70 241,589.7 17 332 243.3 239,946 17 332 242.5 239,946 17 332 242.5 80 292,620.7 20 299 221.37 293,996.5 20 299 220.8 293,996.53 20 299 220.8 90 336,946.3 20 293 198.8 336,731.2 20 293 198.8 336,731.2 20 293 293 100 395,334.4 20 261 191.9 394,547.6 20 261 191.9 394,547.57 20 261 191.9 figure 5. spanning tree of n=20 for problem dat.3 using c1= 0.2, c2= 0.6 and c3= 0.2, and the value of mrcst is 43,066, with maximal link 12 and diameter 653 figure 6. spanning tree of n=20 for problem dat.3 using c1= 0.1, c2= 0.8 and c3= 0.1, and the value of mrcst is 38,798, with maximal link 10 and diameter 392 in order 10 with the maximum number of edges connecting two vertices in the solution (spanning tree) being 8, while the highest number of edges occurs in order 21. note that in the table we present the average value for mrct (the value of mrct for 30 problems in every order and taking the average) and the average value of the average of the largest diameter. the largest diameter recorded in table 1 is the largest diameter of the 30 problems in every graph order, and it is also similar to a maximal link which is taken from the maximal link of the 30 problems in every graph order. figure 3 to figure 6 above shows the visualization of examples of the solutions for vertex orders 10 and 20. due to the space limitation, the visualization for higher-order graphs is not given. figure 3 and figure 4 are the two spanning trees obtained by implementing campos’ algorithm with dierent combinations of values of coecients spanning potential on a graph of order 10. with c1= 0.2, c2= 0.6, and c3= 0.2 in figure 3, the graph shows that the maximal link is 6 and diameter is 1034 and mrcst value is 22,745, while with c1= 0.1, c2= 0.8, c3= 0.1 in figure 4 the graph shows that the maximal link is 5 and diameter is 1087 and mrcst value is 21,642. figures 5 and 6 show the result of implementation on order 20. with c1= 0.2, c2= 0.6, and c3= 0.2 the graph shows that the maximal link is 12 and diameter is 653 and mrcst value is 43,066, while with c1= 0.1, c2= 0.8, c3= 0.1 the graph shows that the maximal link is 10, diameter is 392 and mrcst value is 38,798. moreover, the diameter (the largest shortest path distance) does not always occur in the maximal link. in figure 3 for example, the maximal link is 6 which is the path that connects vertices 5–6–0–3–4–8–2 with a distance of 978, while the diameter is 1034 which is the path that connects vertices 2–8–4–3–7. 5. conclusion we can conclude from the preceding discussion that implemented on a complete weighted connected graph, the edges that form the diameter of the spanning tree may not be the same in the maximal links. moreover, the combination of the coecients of the spanning potential (c2= 0.8 or c2= 0.89) performed slightly better than the value of the coecient suggested by campos and ricardo (2008). from the results, we found that the highest number of edges connecting a pair of vertices is the same for all three variations. the smallest number occurs in order 10 with the maximum number of edges connecting two vertices in the spanning tree being 8, while the highest number of edges occurs in order 60 which is 21. 6. acknowledgment this studywas funded bythe directorate of highereducation under the scheme graduate student research grant project no. 2147/un26. 21/pn/2022, and the authors gratefully acknowledge the funding. © 2022 the authors. page 484 of 485 sari et. al. science and technology indonesia, 7 (2022) 481-485 references borŭvka, o. 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(2002). apolynomial time approximation scheme forthetwo-sourceminimumroutingcostspanningtrees. journal of algorithms, 44(2); 359–378 © 2022 the authors. page 485 of 485 introduction the problem campos' algorithm result and discusssion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 2, april 2018 research paper correlation among education, knowledge, and economics of mother toward antipyretic drug usage for toddler in kangkung village, east oku, south sumatra 2017 rennie puspa novita1*, atika akbari2, nikita surya dharma1, endang putria sukma1 1 1department of pharmacy, faculty of mathematic and natural science, sriwijaya university, jl. palembang-prabumulih, km. 32, ogan ilir, south sumatra, indonesia 2 departement of medical, faculty of medical, sriwijaya university, jl. palembang-prabumulih, km. 32, ogan ilir, south sumatra, indonesia *corresponding author: renniepuspa87@gmail.com abstract fever is a symptom mostly happen with all diseases which condition shows elevated body temperature above normal (38 ◦c) that are common among toddler. handling fever using antipyretics should be considered related to the rationale of its use. rationality aspect which include indication accuracy, precision of medicine, patient accuracy, dosage accuracy and precision of administration, and as well as alert to side effects. handling fever in toddlers is very dependent on the role of parents especially mother. different maternal education, knowledge, and economics will result in the rationale of the use of different antipyretic drugs. this study aimed to investigate whether there is relation among education, knowledge, and economics of mother toward antipyretic drug usage for toddler in kangkung village okut sumsel 2017 by using cross sectional design. the sample was collected using simple random sampling to get 47 samples which fulfilled the inclusion criteria. the data were collected by interview based on questionnaire and analyzed by chi-square test using spss version 23.0. the data presented descriptively showed most of the respondents were highly educated (66%), high knowledge (61.7%), and low economic level (93.6%) and the rational use of antipyretic for toddler were 100% for appropriate drug indication, precision of medicine, patient appropriateness, and alert for side effects, as well as 31.9% dosage precision and mode of administration. the result of chi-square test showed that the p value for education level (p > 0.05) and economic level (p > 0.05) had no significant correlation, meanwhile the knowledge level (p < 0.05) showed significant different to the rational use of antipyretic for toddler. it can be concluded that the knowledge toward of mother affect the rational use of antipyretic for toddler in kangkung village okut regency sumsel 2017. keywords level of education, level of knowledge, level of economic, antipyretic for toddler, rational treatment received: 13 november 2017, accepted: 20 march 2018 https://doi.org/10.26554/sti.2018.3.2.89-93 1. introduction according to kania (2007), 10-30% of patients visiting the doctor’s practice or pediatric intensive care unit were fever patients. therefore, fever in children is the most often complained of by parents. fever is an increase in body temperature from the normal range associated with increasing the set point temperature in the hypothalamus (dinarello and gelfand, 2005). the normal body temperature is 37 ◦c (98.6 °f) and it is generally accepted that rectal temperature ≤ 38 ◦c (100 °f) can be said to be feverish. fever usually occurs in response to infection or in�ammation due to tissue injury or disease. there are also other possible causes of fever, including drugs, toxins, cancer, heat exposure, injury or brain abnormalities, and endocrine system diseases (hormonal or glandular) (davis, 2012). antipyretic is a drug that can lower body temperature, from high body temperature to normal temperature. the antipyretic drugs that can be used are paracetamol, ibuprofen, and asetosal (harahap, 2015). paracetamol is an analgesic-antipyretic drug that is often given to children and is very safe when used at a dose of 50 to 100 mg in one dose, but if the doses are too high it will cause liver damage. the new study found, paracetamol is the leading cause of liver failure in children in australia and new zealand. the researchers identi�ed 54 cases of liver failure in two child hospitals between 2002 and 2012, 14 of these cases were associated with a paracetamol overdose on doses over 4 g daily, and 12 of them were children under the age of �ve. while the number of childhood cases of liver damage is still low, the researchers urged a review of the practice safety in the use of paracetamol (apparovoo, 2012). treatment can be said true, if treatment is done rationally. https://doi.org/10.26554/sti.2018.3.2.89-93 novita et. al. science and technology indonesia, 3 (2018) 89-93 rational aspect which include indication accuracy, precision of medicine, patient accuracy, dosage accuracy and precision of administration, and as well as alert to side e�ects. according to notoadmodjo (2007) all activities of organisms or living things are called behaviors, thus rational treatment is a behavior of the o�cers concerned in medicine, in this case the mother. factors that in�uence behavior are predisposing factors (age, educational level, economy, knowledge), enabling factors (facilities and infrastructure), and reinforcing factors (in�uences from the environment). 2. experimental section 2.1 population the population of this study is all mothers who have children under 5 years who had a fever and using antipyretic drugs in the village kangkung oku east south sumatera. 2.2 sample the number of samples is taken by simple random by using the formula (notoadmodjo, 2007). n = n 1+n(d)2 (1) n = 54 1+54(0.0502) = 47 (2) where n is the large of the population, n is sample size, and d is the desired con�dence level of precision 0.05. based on the calculation with the above formula, the number of samples required for this study was 47 mothers. 2.3 inclusion and exclusion criteria 2.3.1 inclusion criteria 1. living in kangkung village 2. can communicate well 3. have children under 5 years who have had fever and use antipyretic drugs 4. willing to be a respondent 2.3.2 exclusion criteria 1. do not live in kangkung village 2. unable to communicate well or have a mental disorder 3. have a child under 5 years who had a fever, but did not use antipyretic drugs 4. not willing to be a respondent 2.4 operational de�nition 2.4.1 dependent variables the antipyretics use of toddlers rationally. • de�nition : drugs that are meet 5 criteria • measuring tool : questionnaire • measures: interview • measuring scale : ordinal • measurement results : 1. rational if 5 criteria was ful�lled 2. it is irrational if one is not met 2.4.2 independent variables education • de�nition: the last education mother in kangkung village oku timur south sumatera year 2017 • measuring tool : questionnaire • measures : interview • measuring scale : ordinal • measurement results: 1. low (if education ≤ junior high school) 2. high (if education > junior high school) knowledge • de�nition: mother’s knowledge of ripe antipiretik toddler usage rationally • measuring tool : questionnaire • measures : interview • measuring scale : ordinal • measurement results : 1. knowledge low less from 70% 2. high knowledge of more than 70% economics • de�nition : earnings are obtained per month • measuring tool : questionnaire • measures : interview • measuring scale : ordinal • measurement results : 1. low (if ≤ rp 2.206.000) 2. high (if > rp 2.206.000) 2.5 data collection 2.5.1 primary data primary data is data obtained from the distribution of questionnaires to the mothers in kangkung village okut district south sumatra in 2017 includes education, knowledge, and the mother’s economy on the use of antipiretik toddler drugs rationally. 2.5.2 secondary data secondary data is supporting data taken from books, journals, and website theoretically about the usage of antipiretik toddler in a rational and variable (education, knowledge, and economy). 2.6 data analysis the data has been processed, then analyzed using spss® (statistical package for the social sciences) version 23.0. data analysis conducted, among others, as follows: 2.6.1 univariate analysis the analysis was conducted to determine the frequency distribution of each independent variable (education, knowledge, and economy) and dependent variable (rational antipyretic toddler usage), and to explain or describe the characteristics of each of the variables studied. © 2018 the authors. page 90 of 93 novita et. al. science and technology indonesia, 3 (2018) 89-93 table 1. characteristic of respondents independent percentage frequency total variable low high education 16 (34%) 31 (66%) 47 respondents knowledge 18 (38,3%) 29 (61,7) 47 respondents economics 44 (93,6) 3 (6,4%) 47 respondents 2.6.2 bivariate analysis the analysis was conducted to determine the correlation between independent variables (knowledge, education, and economy) and dependent variable (random antipyretic drug usage) using chi-square test with contingency table 2 x 2 on computerized system and signi�cance level at α 0.05 if there is a relation between independent variable and dependent variable and if p value > α value (0,05), then there is no relation between independent variable and dependent variable (notoadmodjo, 2007). 3. results and discussion 3.1 characteristics of education, knowledge, and economics of respondents the result of the characteristic of education, knowledge, and economic of the respondent of this research is presented in the table ??. 3.2 analysis of rationalization of antipyretic toddler drug use indication accuracy, precision of medicine, patient accuracy, dosage accuracy and precision of administration, alert to side e�ects indication accuracy is the accuracy of antipyretic use on the basis of established diagnosis. the diagnosis in this study was obtained from respondents who had previously received diagnosis information from the village midwife. the overall conclusion of the analysis of the rationale of the use of antipyretic drugs for children under �ve in kangkung village consisted of 100% indication accuracy (t1), 100% precision of medicine (t2), patient accuracy (t3) (t4) of 31.9% dosage accuracy and precision of administration, and alert to side e�ects (w) of 100% can be seen in figure 1. the results showed that as many as 15 respondents (31,9%) who in this case is the mother is appropriate in providing pharmacological treatment by giving the drug in accordance with the dose, and e�ective for children. however, more than half of respondents were 32 respondents (68,1%) who did not know how to dose the right drug for children. the inaccuracy occurs because the dose of the drug is given less than the standard dose or the usual dosage. if the given dose is less than or exceed the standard dose, then it is said to be inaccurate dose. if the dose given is less than the standard dose, then the e�ect of therapy will be longer achieved, so the treatment process will take a long time. however, if excessive doses are given, especially for drugs with a narrow range of therapies, it is very risky for toxic e�ects depkes (2006). according to gunawan (2007), excessive paracetamol administration will cause hepatotoxic and analgesic nephropathy. 3.3 analysis of maternal education, knowledge and economics of antipyretic drug usage for toddler 3.3.1 correlation maternal education with antipyretic drugs rationally chi-square test results show that the expected frequency value is eligible, that is, none of the cells have expected frequencies less than 5, and a minimum expectation value of 5.11. the probability value obtained is 0,085 which means p value > α value (0,05), so it can be concluded that there is no signi�cant correlation between educational level toward antipyretic drug usage rationally in kangkung village. this case is not in accordance with the theory notoadmodjo (2003) which states that the higher level of education a person, the higher the level of knowledge. that is, if the level of higher education then it should be higher the level of rational treatment. however, in this study the high or low level of education of mothers in the village of kangkung, does not a�ect the pattern of antipyretic toddler usage. 3.3.2 correlation maternal knowledge with antipyretic drugs rationally chi-square test results show that none of the cells have an expected value of less than 5 with a minimum expectation grade of 5.74. the resulting probability value is 0.006 which means p value < value α (0.05), so it can be concluded that there is a signi�cant relationship between the level of knowledge on the rational use of antipyretic drug under �ve in the village kangkung. based on the percentage of questionnaires about the level of knowledge of mothers in the village of kangkung, the majority of respondents did not know the characteristics of fever correctly. respondents did not know the child’s normal body temperature, so it tends to give antipyretics at <38 ◦c. this case is in accordance with research conducted by hermawati (2012) who get 30% of parents do not know the normal body temperature, so wrong in terms of use of antipyretics. notoadmodjo (2003) states that the level of education is one of the factors that a�ect knowledge. a person who is more educated, will have a wider knowledge than someone with a lower level of education. the results showed that mothers in kangkung village had higher knowledge level than low knowledge level. however, when viewed in terms of age, all respondents are relatively young with age under 35 years, it also a�ects their knowledge of rational treatment. in accordance with the theory of wawan and dewi (2010) which states that factors that can also a�ect the level of knowledge is age, environmental and socio-cultural. the increasing age of a person then the knowledge is also increasing. therefore, because of the young age, more than half of respondents are as many as 32 respondents are not rational in the use of antipiretik toddlers in the village of kangkung. based on the prevalence ratio value seen from the for © 2018 the authors. page 91 of 93 novita et. al. science and technology indonesia, 3 (2018) 89-93 figure 1. analysis of the rationale of the use of antipyretic drugs for children under �ve in kangkung village cohort section value. the resulting value of 0.115, which means that the high level of knowledge of mothers will tend to use the antipiretik toddler drug rationally 0.115 times greater than the mother who has a low level of knowledge. the 95% con�dence interval range (<1), so the maternal knowledge level factor can be summed up as a factor in�uencing the rational use of antipyretic drugs. 3.3.3 correlation mother’s economy with antipyretic drug rationally the result of chi-square test of correlation mother’s economy to rational antipyretic drug usage showed that there are 2 cells or there are 50% cells that have a frequency of less than 5 and a minimum expectation frequency of 0.96. the value of the probability is 0.487 which means p value > α value (0,05), so it can be concluded that there is no signi�cant relationship between economic level to antypiretic toddler usage. based on the survey that has been done, the majority of people in the village of kangkung have a low economic level. only 3 out of 47 respondents who have high economic levels and one of them is still not rational in the use of antipyretic drugs under �ve. in this study, the results obtained are not in accordance with the theory of the depkes (2000) which states that the role of economic status in health is very in�uential on one’s health and tends to have a fear of the cost of health, care and delivery. therefore, the economic status of the mother is very in�uential on the quality of children’s health, where if the mother’s economic status is high then it will tend to do a rational treatment without thinking about cost. the case will occur if the treatment is a doctor’s treatment with prescription which will dispensed by pharmacy. a person with a high economic level, will get drugs with prescription, but if the low level of economy likely only get as necessary (not according to recipe), so it can be said to a�ect the rational treatment. however, in tihis research, all villagers went to the village midwife, so the cost incurred would be in accordance with the economic level of the community in the village of kangkung with the priority of rational treatment. therefore, there is no relationship between maternal economic level with the use of antipyretic drug under �ve in kangkung village. 4. conclusions there is no signi�cant correlation between maternal education and maternal economics with rational antipyretic drug. high or low level of mother education or mother knowledge does not a�ect of antipyretic toddler usage rationally. the health service provided in kangkung village has been adjusted to the economic condition of the community, so that both the high economic community or low will get the same treatment. but, there is a signi�cant correlation between mother’s knowledge with rational antipyretic drug usage in kangkung village, east oku district, south sumatra in 2017. mothers who have a high level of knowledge will tend to use the antipyretic toddler drug rationally 0.115 times greater than the mother who has a low level of knowledge. 5. acknowledgement authors would like to express their gratitude toward sriwijaya university pnbp sateks research grant that made this research possible. references apparovoo, p., 2012. penggunaan parasetamol oleh pelajar sma. universitas sumatera utara. davis, a. t., 2012. dasar biologis dan klinik penyakit infeksidasar biologis dan klinik penyakit infeksi. universitas gajah mada press. © 2018 the authors. page 92 of 93 novita et. al. science and technology indonesia, 3 (2018) 89-93 depkes, 2000. paradigma baru pelayanan kesehatan indonesia. depkes ri. depkes, 2006. penggunaan obat rasional. depkes ri. dinarello, c. a., gelfand, j. a., 2005. fever and hyperthermia :harrison’s principles of internal medicine, 16th edition. the mcgraw-hill company. gunawan, s. g., 2007. farmakologi dan terapi. fakultas kedokteran universitas indonesia. harahap, n. a., 2015. tingkat pengetahuan pasien dan rasionalitas swamedikasi di tiga apotek kota panyabungan. universitas sumatera utara. hermawati, d., 2012. pengaruh edukasi terhadap tingkat pengetahuan dan rasionalitas penggunaan obat swamedikasi pengunjung di dua apotek kecamatan cimanggis depok. universitas indonesia. kania, n., 2007. kejang pada anak. sarana panca karya nusa. notoadmodjo, s., 2003. pendidikan dan perilaku kesehatan. pt rineka cipta. notoadmodjo, s., 2007. promosi kesehatan dan ilmu perilakupromosi kesehatan dan ilmu perilaku. pt rineka cipta. wawan, a., dewi, m., 2010. teori dan pengukuran pengetahuan, sikap, dan perilaku manusia. nuha medika. © 2018 the authors. page 93 of 93 introduction experimental section population sample inclusion and exclusion criteria inclusion criteria exclusion criteria operational definition dependent variables independent variables data collection primary data secondary data data analysis univariate analysis bivariate analysis results and discussion characteristics of education, knowledge, and economics of respondents analysis of rationalization of antipyretic toddler drug use indication accuracy, precision of medicine, patient accuracy, dosage accuracy and precision of administration, alert to side effects analysis of maternal education, knowledge and economics of antipyretic drug usage for toddler correlation maternal education with antipyretic drugs rationally correlation maternal knowledge with antipyretic drugs rationally correlation mother’s economy with antipyretic drug rationally conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper dynamic modeling and forecasting data energy used and carbon dioxide (co2) edwin russel1,5, wamiliana2*, nairobi3, warsono2, mustofa usman2, jamal i. daoud4 1department of management, faculty of economics & business, universitas lampung, 35145, indonesia2department of mathematics, faculty of mathematics and sciences, universitas lampung, 35145, indonesia3department of development economics, faculty of economics & business, universitas lampung, 35145, indonesia4department of science in engineering, kulliyyah of engineering, international islamic university malaysia, 50728, malaysia5doctoral student, department of mathematics, faculty of mathematics and sciences, universitas lampung, 35145, indonesia *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstractthe model of vector autoregressive (var) with cointegration is able to be modified by vector error correction model (vecm). becauseof its simpilicity and less restrictions the vecm is applied in many studies. the correlation among variables of multivariate time seriesalso can be explained by vecm model, which can explain the effect of a variable or set of variables on others using granger causality,impulse response function (irf), and forecasting. in this study, the relationship of energy used and co2 will be discussed. thedata used here were collected over the year 1971 to 2018. based on the comparison of some criteria: akaike information criterioncorrected (aicc), hannan-quin information criterion (hqc), akaike information criterion (aic) and schwarz bayesian criterion(sbc) for some var(p) model with p= 1,2,3,4,5, the best model with smallest values of aicc, hqc, aic and sbc is at lag 2 (p= 2). thenthe best model found is vecm (2) and further analysis such as granger causality, irf, and forecasting will be based on this model. keywordscarbon dioxide (co2), energy used, cointegration, var model, vecm model received: 5 january 2022, accepted: 2 april 2022 https://doi.org/10.26554/sti.2022.7.2.228-237 1. introduction currently, studies on the phenomenon of global warming caused by the use of fossil fuels, energy used, the use of electricity consumption, and the increment of the steel industry have been conducted by many scientists (anjana and kandpal, 1997; sakamoto and tonooka, 2000; di lorenzo et al., 2013; aye and edoja, 2017; balsalobre et al., 2018; mahmood et al., 2019; wasti and zaidi, 2020; munir et al., 2020). developed countries have sought to reduce the amount of co2 emissions (known as one of the representative greenhouse gases) (un unced, 1992; un unced, 1996; mahmood et al., 2019). developed countries that use a lot of fossil fuels, use more electricity to produce co2 emissions, for example, japan contributed about 5% of world co2 emissions in 1990 (oecd, 2005). since the era of the industrial revolution began in the early 19th century, the growth in the use of fuels (fossil), the discovery and increasing of electricity consumption, and the increase in the steel industry have caused substantial climate change and global warming. co2 emissions to the atmosphere have caused an increase in the greenhouse eect and caused the surface temperature of the earth to increase (epa, 2017). therefore, industrialization growth, intensive use of fossil fuels, and electricity use have damaged the environment and stimulated global warming (dong et al., 2018; al araby, 2019). carbon dioxide (co2) is considered to be one of the most dominant causes of increasing global warming and climate change (ipcc, 2014; al araby, 2019; hasnisah et al., 2019). increasing energy use and concerns about global warming and climate change, have encouraged many developed countries and companies to apply strategies in order to cut energy use and increase clean energy production (benedetti et al., 2017; faizah, 2018). economic growth in many developed countries is closely related to increasing co2 emissions (mirza and kanwal, 2017; charfeddine, 2017; hanif, 2018). increased co2 emissions are positively correlated with energy consumption, the use of fossil fuels and electricity, which causes an increase in pollution. thus, manydeveloped countries have targeted using renewable energy sources to reduce co2 emissions in an eort to reduce pollution (balogh and jámbor, 2017; ito, 2017; balsalobre et al., 2018). abolhosseini et al. (2014) have investigated the eect of renewable energy on reducing the emission of co2. the studies about the correlation between the emission of co2 and the use of electricity have been conducted by many https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.228-237&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.228-237 russel et. al. science and technology indonesia, 7 (2022) 228-237 scientists, including (tamba et al., 2017; bah and azam, 2017; akpan and akpan, 2012). the var or vecm model for modeling energy and economics have been used by many researchers because of too many problems concerning energy, climate change, co2 and renewable energy (forero, 2019; warsono et al., 2019a, warsono et al., 2019b; wang et al., 2018; ito, 2017). the used of vecm modeling to nd the correlation between food price index and crude oil price had been investigated by aynur (2013). yu et al. (2006) investigated the correlation between the price of vegetable oil and higher crude oil using causality approach and cointegration. the correlation and forecasting between index’s prices coal of two coal companies using var model was discussed by warsono et al. (2019a). in order to analyze macroeconomic data, sims (1980) introduced var model. in economy and nance, var model plays an important role (kirchgässner et al., 2012; hamilton, 1994). var model are natural tool for forecasting (lütkepohl, 2013). vector error correction model (vecm) will be used by modifying var model if the data has cointegration. if the variables have a common stochastic’s trend, then theyare called cointegrated (engle and granger, 1987; granger, 1981). the var model is not convenient to be used if cointegration occurs in the variables. in this case specic parameterizations will be considered, and vecm is the commonly used model to elaborate the cointegration among the variables. there are a lot of researchs that have been done concerning the eect on forecasting by cointegration (lütkepohl, 2005; campiche et al., 2007; yu et al., 2008; hunter et al., 2017). the comparison the forecasts generated from an estimated vecm model by assuming that the cointegrating rank and the lag order are known, with those from an estimated vector autoregressive (var) model in levels with the correct lag was investigatedbyengleandyoo(1987). theresult is thatvecm model is better than var model, because vecm allows us to explain the correlation of the long-run and the short-run of nonstationary variables. the aim of this research is to explain the patterns of the relationship between carbon dioxide (co2) and energy used using vecm approach in an indonesian case. studies on modeling the correlation between co2 and energy used using multivariate time series data by means of vecm modeling are relatively rare. therefore, this study is an attempt to ll this gap by analyzing the data energy used and carbon dioxide (co2) using vecm approach. 2. the method in this study, the method to analyze the data energy used and carbon dioxide (co2) is a vecm model, with the following steps: rst, the assumptions stationary data will be checked; second, the optimal lag will be determined for the vector autoregression (var) model using the aicc, hqc, aic, and bsc criterion information; third, after the optimal lag has been obtained, the cointegration test will be carried out by using the johansen test; fourth, after obtaining rank cointegration, the vecm model is built. based on the best vecm model obtained, the analysis of irf, granger causality and forecasting is carried out (hamilton, 1994; lütkepohl, 2005; tsay, 2014; wei, 2019). 2.1 dynamic modeling in studying time series data, we often face with many variables, yit, where i= 1, 2, ..., p and the data are taken in a sequence of time, t. let yt= [y1t, y2t, ..., ypt]’, where yit is the ith component variable at time t and it is a random variable for each i and t (wei, 2019). because most of standard method of statistical theory on random samples are not applicable, so dierent methods are needed (tsay, 2014; wei, 2019). in decision making, we need to get accurate prediction of those variables, and it require understanding the relationships among those variables. it is assuming that the data is stationar. by checking the plot of the data we know the stationary of the data. if the data are uctuating around certain number then it is stationary, if not then the data are nonstationary. besides, we also can use augmented dickey-fuller (adf) test. autocorrelation function (acf) graph also can be used. the adf-test with lag-p, is dened as: δyt = 𝛼 + 𝜙yt−1 + p−1∑︁ i=1 𝜙i ∗ δyt−i + ut (1) δyt= yt-yt−1 and ut is white noise. ho: 𝜙= 0 is the null hypothesis, and ha: 𝜙<0 is the alternative hypothesis, 𝛼= 0.05 is level of signicance. if 𝜏<-2.57, then it rejects ho, or if the p value<0.05 (tsay, 2005; brockwell and davis, 2002). the test statistic is adf 𝜏 = 𝜙 se(𝜙) (2) 2.2 cointegration granger(1983) whorst statedthetermcointegration. granger (1983) has investigated of how the relationship between cointegration and modeling with error correction. this study has attracted much attention in econometric, nancial and in various elds of science involving multivariate time series data that has a cointegration between variables (johansen, 1995; engle and granger, 1987). over the past 25 years, this approach has contributed a lot to various scientic studies, for example in the elds of nance, business, and environment. cointegration is the key concepts of in econometrics and modern time series analysis. thedevelopmentofmethodof inferential andestimation is given by johansen (1988). in general, yt is nonstationary with order d, i(d) process, if (1-b)dyt= zt , where zt is stationary and invertable (mittnik et al., 2007; tsay, 2005, tsay, 2014). if there is a cointegration, then the rank of the cointegration should be tested (tsay, 2005; tsay, 2014), and to test the rank © 2022 the authors. page 229 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 of cointegration we can use trace test and test of maximum eigenvalues. for trace test, the null hypothesis: there are at most r positive eigenvalues, and the test: tr(r) = −t k∑︁ i=r+1 ln(1 − _̂ i) (3) the test for maximum eigen value: the null hypothesis: there are r positive eigen values, and the test statistics: _max(r, r + 1) = −t ln(1 − _̂ i) (4) _̂ i=estimateofeigenvalue,t=totalnumberofobservations, and k= total number of endogeneous variables. 2.3 vector autoregressive in the modeling with vector autoregressive (var) models means that the future values of the process are weighted sum of present and past values with some noises (mittnik et al., 2007). tsay (2014) and wei (2019) stated that this model is used comprehensively in business, nancial and econometric studies because: (1) the model is easy to estimate; (2) the var model have been investigated expansively in the literature (warsono et al., 2019a, warsono et al., 2019b; wei, 2006; lütkepohl, 2005; lütkepohl,2013), and(3) vectorautoregressionmodels in multivariate analysis are like multivariate linear regression. the k-dimensional var process with order p, var(p) is: yt = `0 + φ1yt−1 + ..... + φpyp + ut (5) or φp(b)yt = `0 + ut (6) where ut is k-dimensional vector white noise process with mean vector 0kxl and variance covariance matrix ∑ , vwn(0,∑ ), φp(b) = i − φ1b − ... − φpbp. (7) if the roots of |𝛾pi-𝛾p−1φ1...-φp|= 0 are all lie inside the unit circle, then var model is invertible and it will be stationary. 2.4 vector error correction model a modied var model which has cointegration among the variables. if r≤k is the rank of cointegration, p is the lag of endogeneous variable, the general form of vecm(p) is: δyt = πyt−1 + p−1∑︁ i=1 γiδyt−i + ut (8) some advantages of vecm(p) model’s applications: (1) the multicollinearity is reduced, (2) all information about long-run impacts is summarized in the level matrix (denoted by π), (3) the easier of the interpretation of estimates, and (4) vecm model is easier to interprete (juselius, 2006). the criteria of information aic, sbc, are used to nd the best model of vecm(p). 2.5 normality test to check the normality of residual, the jarque-bera (jb) test is used. besides, the residuals plot’s performance will be considered. the jb test is: jb = n − k 6 [ s2 + (k-3)2 4 ] (9) where: n = number of samples s = expected skewness = 1 n ∑n i=1(yi − ȳ) 3 ( 1n ∑n i=1(yi − ȳ)2)3/2 (10) k = expected excess kurtosis = 1 n ∑n i=1(yi − ȳ) 4 ( 1n ∑n i=1(yi − ȳ)2)2 (11) k = the number of independent variables jarque-bera test has x2 distribution (jarque and bera, 1987). 2.6 test for granger causality many researchers have argued concerning the meaning and nature of causality, and the important role of casuality in the study economic (sampson, 2001). consider a var(p) model (wei, 2019). φp(b)yt = \0 + ut (12) the vector yt is partitioned into two components, yt=��y ′it,y ′2t��’, then the equation (12) can be written as:[ φ11(b) φ12(b) φ21(b) φ22(b) ] [ y1t y2t ] = [ \1 \2 ] + [ u1t u2t ] (13) if the value of φ12(b)= 0, then equation (13) can be written as follows: φ12(b)y1t = \1 + u1t φ22(b)y2t = \2 + φ21(b)y1t + u2t (14) the interpretation is as follows: the future values of y2t are impacted by its own past and the past of y1t. the future values of y1t are impacted by its own past. this idea is called as the granger causality, because it is rst introduced by granger (1969). © 2022 the authors. page 230 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 2.7 impulse response function consider the var model as follows (hamilton, 1994): yt = ` + `t + ψ1ut−1 + ψ2ut−2 + ..... the interpretation of matrix ψs is as follows: 𝜕yt+s 𝜕y′t = ψs. if the value of ut is changed by 𝛿1, at the same time ut−1 is changed by 𝛿2, ..., and the ut−n is changed by 𝛿n, so that the combined impact to the value of vector yt+s is as follows: δyt+s = 𝜕yt+s 𝜕y1t 𝛿1 + 𝜕yt+s 𝜕y2t 𝛿2 + ... + 𝜕yt+s 𝜕ynt 𝛿n = ψs𝛿 (15) where 𝛿=(𝛿1, 𝛿2, ..., 𝛿n)’andthegraphof therow i, column j element of ψs 𝜕yi,t+s 𝜕y jt as a function of s is called impulse response function. 3. results and discussion to analysis the data energy used and co2, the sas program is used (sas/ets 13.2, 2014). the assumption of stationarity will be checked by: (1) evaluate the behavior of the plot of data, (2) acf plot of data, and (3) augmented dickey fuller test. the data used in this research are the use of energy (enr) and carbone dioxide (co2) emission. the plot of the data is shown in figure 1. figure 1. plot of energy used (enr) and co2 emission table 1. unit roots test oradftest forenergyused and co2 variable type lags rho p-value tau p-value energy (enr) zero mean 2 0.8776 0.8835 3.30 0.9996 single mean 2 -0.0717 0.9497 -0.12 0.9401 trend 2 -8.2149 0.5260 -1.90 0.6384 co2 zero mean 2 1.4082 0.9545 2.80 0.9983 single mean 2 0.5399 0.9752 0.49 0.9843 trend 2 -9.9202 0.3909 -1.82 0.6779 figure 2. trend and correlation analyisis of energy used (enr) figure 3. trend and correlation analysis of co2 from figure 1, we can see that energy used and co2 emission, the trend are increase and uctuative. figure 2 and 3 the plot of autocorrelation function (acf) for energy and co2 the autocorrelations are decrease veryslowly. from table 1, adf test for energy (enr) and co2 the tau-test for single mean at lag 2 not signicant with p-values= 0.9401 and 0.9843, respectively. these means that energy used and co2 are non-stationary. to attain the stationary data, the dierencing method is used. figure 4. trend and correlation analyisis of energy used after dierencing, d=1 from figures 4 and 5 of data enr and co2 after differencing with d= 1, the data are uctuated around certain © 2022 the authors. page 231 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 figure 5. trend and correlation analyisis of co2 after dierencing, d=1 table 2. adf unit roots test of energy (enr) and co2 after dierencing, d=1 variable type lags rho p-value tau p-value energy (enr) zero mean 2 -51.8104 <0.0001 -3.42 0.0011 single mean 2 -1962.80 0.0001 -4.57 0.0007 trend 2 320.6803 0.9999 -4.66 0.0030 co2 zero mean 2 -14.7087 0.0050 -2.33 0.0205 single mean 2 -98.1031 0.0003 -4.50 0.0008 trend 2 -98.1986 <0.0001 -4.43 0.0055 number, the data are stationary. the adf test for data enr and co2 the tau-test= -4.57 with p-value= 0.0007, tau-test= -4.57 with p-value= 0.0008, respectively. thus, after the rst dierencing, the data enr and co2 are stationary. 3.1 test for lag optimum by using criteria aic, sbc, hqc and aicc, we nd the best var model from endogeneous variables that are enr and co2, where the results are as follows: table 3. criteria to select of lag var model for all endogeneous variables var(p) lag order selection criteria criteria var(1) var(2) var(3) var(4) var(5) aicc -10.9638 -11.2889* -11.0036 -10.7606 -10.5612 hqc -10.8947 -11.2045* -10.9383 -10.7620 -10.6956 aic -10.9857 -11.3567* -11.1520 -11.0375 -11.0329 sbc -10.7375 -10.9387* -10.5609 -10.2697 -10.0848 from table 3, at lag 2, the smallest information criteria (*) of aicc, aic, and hqc occur. thus, the test of cointegration is conducted at lag 2. 3.2 test for cointegration table 4 is the result of cointegration testing with the null hypothesis: rank= r, no cointegration with the alternative: rank>r, there is cointegration. from table 4 we can conclude that the test results are that rank>r= 1, or rank r= 2. based on these results, the vecm model with cointegration rank= 2 will be used. 3.3 the estimation of parameters vecm(2) model based on the above analysis, we have chosen the model for energy used (enr) and co2 data is vecm(2) with the cointegration rank= 2 as the best model. table 5 is the estimate parameter of (𝛽), the long-run parameter beta estimate. table 6 give an estimate parameter (𝛼), adjustment coecient alpha estimates, and table 7 give the estimate parameter π= 𝛼*𝛽 ’. the estimate parameters of vecm(2) is: δyt = πyt−1 + γ1δyt−1 + yt (16) δ [ yt ] = [ −0.7393 0.0355 4.5149 −1.6776 ] yt−1+[ −0.1151 −0.0130 −3.1509 0.6297 ] δyt−1 + [ yt1 yt2 ] (17) figure 6. prediction error normality for energy (enr) figure 7. prediction error normality for co2 3.4 normality of residual table 9 is the result of testing with the null hypothesis: the residuals are not correlated. the results for models ar(1), ar(1,2), ar(1,2,3) and ar(1,2,3,4), the null hypothesis was not rejected. so the residuals are not correlated. table 10 is the result of the normality distribution test for residual enr and co2 data, the results show that the jb test for both enr and co2 data is rejected with p-value<0.0001. so the residuals are not normally distributed. however, if we look at the results © 2022 the authors. page 232 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 table 4. cointegration rank test using trace statistics h0:rank= r h1:rank>r eigenvalue trace p-value drift in ecm drift in process 0 0 0.6653 67.5644 <0.0001 constant linear 1 1 0.4250 22.6894 <0.0001 table 5. the long-run parameter beta estimate (𝛽) when rank= 2 variable 1 2 enr(3) -3.04277 15.87431 co2 1.00000 1.00000 table 6. adjustment coecient alpha (𝛼) estimates when rank= 2 variable 1 2 enr(3) 0.06894 -0.03336 co2 -1.64649 -0.03118 of figures 6 and 7, it shows that the residual distribution for the enr and co2 data is not far enough from the normal distribution. table 10 also shows that the arch eect where the results conclude that there is no arch eect with p-values for enr and co2 data are 0.4890 and 0.8696, respectively. 3.5 test for stability model table 11 is the result of the analysis of the root ar characteristic polynomial and it is found that all modulus<1. so the vecm(2) model has high stability. 3.6 test for the fitness of model model vecm(2) given in (17) can be written as follows: δyt1 = −0.7393yt1−1 + 0.0355yt2−1 − 0.1151yt1−1− 0.0130yt2−1 + yt1 (18) δyt2 =4.5142yt1−1 − 1.6776yt2−1 − 3.1509yt1−1+ 0.6297yt2−1 + yt2 (19) the vecm(2) model in equation (17) if described in the form of two univariate models with dependent variables enr and co2 (model (18) and model (19)), respectively. table 12 is a test of signicance for models (18) and (19) and both models are signicant with p-values of 0.0001 and <0.0001. the r-square for enr is 0.4258, this means that 42.58% the variance of enr is explained by the model (18) and the rsquare forco2 is0.7115. thismeans that71.15%thevariance of co2 is explained by the model (19). table 7. the estimate parameter π= 𝛼*𝛽 ’ variable enr(3) co2 enr(3) -0.73932 0.03558 co2 4.51488 -1.67767 table 8. model parameter estimates equation parameter estimate standard error t value pvalue variable d_enr ar1_1_1 -0.73932 0.20510 enr(t-1) ar1_1_2 0.03558 0.03844 co2(t-1) ar2_1_1 -0.11508 0.15586 -0.74 0.4650 d_enr(t-1) ar2_1_2 -0.01300 0.02941 -0.44 0.6611 d_co2(t-1) d_co2 ar1_2_1 4.51488 1.02976 enr(t-1) ar1_2_2 -1.67767 0.19301 co2(t-1) ar2_2_1 -3.15094 0.78252 -4.03 0.0003 d_enr(t-1) ar2_2_2 0.62977 0.14766 4.26 0.0001 d_co2(t-1) 3.7 analysis granger-causality one of a key question about var model or vecm model is how useful some variables are for forecasting others, and this question usually addressed when we study about the relationship and forecasting among economic variables (hamilton, 1994). the null hypothesis of the granger causality test is that group 1 is induced only by itself and not by group 2 (sas/ets 13.2, 2014). figure 8. impulse response function for shock in variabel energy (enr) table13showsthat theenrasgroup1andco2 asgroup 2 (test 1). the result with chi-square test=1.09 with p-value is 0.5808>0.05, thus we can conclude that there is no evidence to reject the null hypothesis. therefore, enr is induced by itself and not by co2. this means that past information on co2 does not aect current energy used (enr). from the test © 2022 the authors. page 233 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 table 9. univariate model ar diagnostics variable ar1 ar2 ar3 ar4 f value p-value f value p-value f value p-value f value p-value enr 1.17 0.2861 2.19 0.1264 2.48 0.0777 1.70 0.1745 co2 0.35 0.5594 0.21 0.8077 0.15 0.9316 0.41 0.8031 table 10. univariate model white noise diagnostics variable durbin watson normality arch chi-square p-value f value p-value enr 2.02723 21.81 <0.0001 0.49 0.4890 co2 2.12368 93.22 <0.0001 0.03 0.8696 table 11. test for stability model index real imaginary modulus radian degree 1 0.54588 0.00000 0.5459 0.0000 0.0000 2 -0.07088 0.82042 0.8235 1.6570 94.9380 3 -0.07088 -0.82042 0.8235 -1.6570 -94.9380 4 -0.30641 0.00000 0.3064 3.1416 180.0000 results for test 2 shows that the co2 as group 1 and enr as group 2, the results show where chi-square test= 21.78 with p-value is <0.0001, the null hypothesis is rejected. therefore, co2 is inuenced not only by past information from itself (co2), but also by information of the past of energy used (enr). so, there is granger causal of enr to co2. figure 9. impulse response function for shock in variabel co2 3.8 impulse response function (irf) figure 8 is the graph of impulse response function if there is a shock 1 standard deviation in enr and its eect to the variable enr and co2. if there is a shock of one standard deviation inenr, this causes theenrgives responsepositively for the rst four years and after that the eect getting smaller and smaller. the response of enr itself from the rst year table 12. test for signicant of the model variable r-square standard deviation f value p-value enr 0.4258 0.02513 9.14 0.0001 co2 0.7115 0.12619 30.42 <0.0001 to the fourth year are: 0.1456, 0.1671, 0.1329, and 0.0738, respectively. if there is a shock of one standard deviation in enr, this causes the co2 gives response uctuatively from the rst year up to the twelf year, in the rst and second year the response are positive, the three and fourth year the response are negative, in the fth and sixth year the response are positive. in the seventh and eight year the responses are negative. after the tenth year the impact are getting smaller toward to the equilibrium condition. the response of co2 from the rst year to the eight years are: 1.3639, 3.2842, -0.3296, -1.3446, 0.7917, 1.0298, -0.5649, and -0.5514, respectively. figure 10. model and forecasts for enr figure 9 is the graph of impulse response function if there is a shock 1 standard deviation in co2 and its impact to the variables energy (enr) and itself co2. shock of one standard deviation in causes the enr gives a response uctuatively, but only has small impact. in the rst and second year the response is positive, in the third year to the fourth year the response is negative. for energy (enr) the response from the rst year to the third year are: 0.0226, 0.0152, and -0.0093. after the fourth year the response getting smaller tend to the zero poin (equilibrium point). shock of one standard deviation in co2, causes the co2 itself gives a response uctuatively. in the rst © 2022 the authors. page 234 of 237 russel et. al. science and technology indonesia, 7 (2022) 228-237 table 13. test for granger-causality test group variable null hypotheses (h0) chi-square p-value conclusion 1 group 1. variables: enr group 2. variables: co2 h01 : enr is aected by itself and not by co2 1.09 0.5808 do not reject h0 2 group 1. variables: co2 group 2. variables: enr h02 : co2 is aected by itself and not by enr 21.78 <0.0001 reject h0 year to the second year the responses are negative, in the third and fourth year the response is positive, in the fth and sixth year the response is negative. the response of co2 from the rst year to the eight years are: -0.0479, -0.5967, 0.1506, 0.4038, -0.1488, -0.2467, 0.1391, and 0.1494. table 14. forecasting for the next sixth periods of energy (enr) and co2 variable obs forecast standard error 95% condence limits enr3 45 0.87741 0.02513 0.82815 0.92667 46 0.88757 0.03827 0.81255 0.96258 47 0.89682 0.05068 0.79750 0.99614 48 0.89405 0.06241 0.77173 1.01636 49 0.89052 0.07319 0.74707 1.03397 50 0.89437 0.08252 0.73264 1.05610 co2 45 2.27649 0.12619 2.02917 2.52381 46 2.39082 0.17699 2.04393 2.73772 47 2.09083 0.21615 1.66718 2.51449 48 2.07781 0.24947 1.58886 2.56676 49 2.29274 0.28385 1.73640 2.84909 50 2.27709 0.31352 1.66259 2.89158 figure 11. model and forecasts for co2 3.9 forecasting in forecasting data for energy used (enr) and co2, we used model given in equation (18) and (19), the models are significant with p-values 0.0001 and <0.0001 and with r-squares 0.4258 and 0.7115. these univariate models will be used for forecasting. figures 10 and 11 showthat the univariate models (18) and (19) t very well with the enr and co2 data where the observation values are very closed to their predictive values. so, the models used are very reliable and sound good. the forecasting for the next six years, the values are not to much variation, but the condence interval of forecasting are bigger as the period longer (table 14). 4. conclusions this research has investigated and examined the correlation between energy used (enr) and co2 emission. there is cointegration correlation between energy used and co2 emission with the rank=2. by using smallest criteria of information of aicc, hqc, aic and hqc, the best model is var(p) with lag p=2. by cointegration test and smallest criteria of information the best model is vecm(p) with lag p=2. from the granger causality it was found that there is unidirection eect namely there is causal eect of energy used to co2 emission. from impulse response function analysis shows that if there is shock of one standard deviation of energy used, the impact on energyused itself is small, but the impact on co2 emission is uctuated and relatively long periode of time to attain the stability condition. if there is shock of one standard deviation of co2 emission, the impact on energy used is small, but the impact on co2 emission itself is uctuate and relatively long periode of time to attain the stability condition. the forecasting result for the next six period by using model vecm(2) the energy used showed ther trend is increase, while the emission uctuate. 5. acknowledgment the authors would like to thank universitas lampung for partially nancial support for this study. references abolhosseini, s., a. heshmati, and j. 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(2019). multivariate time series analysis and applications. john wiley & sons yu, t. h. e., d. a. bessler, and s. w. fuller (2006). cointegration and causality analysis of world vegetable oil and crude oil prices. american agricultural economics association annual meeting, long beach, ca, july 23-26 yu, w., g. ju’e, and x. youmin (2008). study on the dynamic relationship between economic growth and china energy based on cointegration analysis and impulse response function. chinapopulation, resources andenvironment, 18(4); 56–61 © 2022 the authors. page 237 of 237 introduction the method dynamic modeling cointegration vector autoregressive vector error correction model normality test test for granger causality impulse response function results and discussion test for lag optimum test for cointegration the estimation of parameters vecm(2) model normality of residual test for stability model test for the fitness of model analysis granger-causality impulse response function (irf) forecasting conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper catalytic oxidative desulfurization of dibenzothiophene by composites based ni/al-oxide nur ahmad1, alfan wijaya2, amri2, erni salasia fitri2, fitri suryani arsyad3, risfidian mohadi1,2, aldes lesbani1,2* 1graduate school of mathematics and natural sciences, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia2research center of inorganic materials and coordination complexes, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia3department of physics, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstractin the present study, composite layer double hydroxide-metal oxide (ni/al-tio2 and ni/al-zno) was successfully prepared andused as catalyst of oxidative desulfurization of dibenzothiophene. characterization of catalyst was used xrd, ftir, and sem-eds.the structure of ni/al-ldh, tio2, and zno in composite ni/al-tio2 and ni/al-zno was consistent, which also indicated that thepreparation of composite did not change the form of precursors. ftir spectra of ni/al-tio2 and ni/al-zno absorption band at 3398,1639, 1339, 832, 731, and 682 cm−1. the catalysts have an irregular structure, tio2 and zno adhere to the surface of ni/al-ldh.the percent mass of ti and zn on the composite at 29.3% and 18.2%, respectively. the acidity of ni/al-ldh increased after beingcomposited with tio2 and zno. the optimum reaction time, dosage catalyst, and temperature were 30 min, 0.25 g, and 50°c,respectively, and n-hexane as a solvent. the percentage conversion of dibenzothiophene on ni/al-ldh, tio2, zno, ni/al-tio2, andni/al-zno were 99.44%, 91.92%, 95.36%, 99.88%, and 99.90%, respectively. the catalysts are heterogeneous system and theadvantage is that can be used for reusability. after 3 times catalytic reactions, the conversion of dibenzothiophene still retains morethan 80%, even ni/al-tio2 and ni/al-zno composites still 97.79% and 98.99%, respectively. keywordsdesulfurization, dibenzothiophene, layered double hydroxide, composite received: 11 april 2022, accepted: 15 july 2022 https://doi.org/10.26554/sti.2022.7.3.385-391 1. introduction fuel oil is an energy source that has a vital role in the global economy (zeng et al., 2017). the fuel is oil from exploration on the earth, known as petroleum. although the availability of petroleum continues to run low, its supply is still sucient for the needs of human life on earth. however, the intensive use of petroleum, especially in transportation, causes gas emissions to be produced, namely sox (mahmoudi et al., 2021). sox signicantly contributes to air pollution, acid rain, and damage to the gas emission section of vehicles (abedini et al., 2021; kang et al., 2018; mousavi-kamazani et al., 2020). the specications issued by japan and european commission show that the sulfur content in the oil is constantly changing and revising due to the eects caused when the sulfur content is found in large quantities in fuel oil. in 2005, the sulfur content in fuel oil allowed in europe was 10 ppm (ren et al., 2016). the same thing happened in america, which revised the permissible sulfur content in fuel oil to 15 ppm in 2006 (bazyari et al., 2016). the current trend shows that the sulfur content in fuel oil is a maximum of 10 ppm (luna et al., 2022). sulfur compounds in fuel oil are organosulfur such as dibenzothiophene(dbt) andderivatives (mujahidetal.,2020; ye et al., 2020). the chemical structure of dibenzothiophene is shown in figure 1. figure 1. chemical structure of dibenzothiophene reducing sulfur content in dibenzothiophene is known as the desulfurization process using the catalytic principle of oxidation. the success of the desulfurization process is highly dependent on the catalyst used, considering the process applied in catalytic oxidation. malani et al. (2021) used microorganisms in the desulfurization process known as biodesulfurization. however, this method has diculties in controlling the use https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.385-391&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.385-391 ahmad et. al. science and technology indonesia, 7 (2022) 385-391 of microorganisms and in the treatment of microorganisms, so chemical methods with the principle of catalytic oxidation continue to be developed until now. several desulfurization technologies for dibenzothiophene compounds have been carried out such as photocatalytic desulfurization (mgidlana et al., 2021), adsorptive desulfurization (subhan et al., 2019), and oxidative desulfurization (ods) (li et al., 2020). in addition, in petroleum which is explored together with gas containing sulfur, the desulfurization process is carried out using a separator column and the extractive desulfurization process (eds) (rezaee et al., 2021). until now, the desulfurization process is still beingresearched to nd eective materials to convert sulfur by chemical processes, especially with the principle of catalytic oxidation reactions using synthesized catalysts. catalysts have been reported for desulfurization of dbt, including montmorillonite (kang et al., 2018), fe promoted ni/co-mo/al2o3 (muhammad et al., 2018), silica (teimouri et al., 2018), and layered double hydroxide (masoumi and hosseini, 2020; wu et al., 2018). the potential catalyst to be used is layered double hydroxide (ldh). ldh can be made easily, with low cost, and has a high-eciency level (taher et al., 2021). ldh is derived from the mineral clay brucite, whose general formula is mg(oh)2. in the catalytic process, ldh has been used for water remediation (karim et al., 2022), n-heptane hydroconversion (zhu et al., 2019), and biodiesel production (gabriel et al., 2021). ldh is interested in catalysis due to its large surface area and homogeneous distribution of various essential components (zhu et al., 2019). the disadvantage of ldh is easily exfoliated, so the reusability of ldh is less attractive. therefore, ldh is composited with metal oxide. ldh is easily made into composites with metal oxides by calcining at high temperatures to remove organic pollutants (dang et al., 2021). in the experiment part, ni/al-tio2 and ni/al-zno were prepared as catalysts and dbt was the sulfur compound. characterization of catalysts used xrd, ftir, and sem-eds to know the successful preparation of the catalysts. the process of optimizing the oxidative desulfurization of dbt was carried out with variations in time, uv-vis spectrum, the dosage of catalyst, temperature, solvent (n-pentane, n-hexane, and n-heptane), acidity test, heterogeneous test, and reusability. 2. experimental section 2.1 chemicals and instrumentation dibenzothiophene (dbt) was obtained from sigma-aldrich and directly used as received. other chemicals such as hydrogenperoxide(h2o2), acetonitrile (ch3cn),pyridine(c5h5n), n-pentane (c5h12), n-hexane (c6h14), n-heptane (c7h16), nickel (ii) nitrate hexahydrate (ni(no3)2.6h2o), aluminum nitratenonahydrate (al(no3)2.9h2o),sodiumcarbonate (na2 co3), and sodium hydroxide (naoh), titanium(iv) oxide (tio2), and zinc(ii) oxide (zno) were also directly used without further purication. water was supplied from the research center of inorganic materials and complexes fmipa universitas sriwijaya after several cycles of water purication using puriter. instrumentation such as x-ray diractometer (xrd) type rigaku miniex-6000, emc-18pc-uv spectrophotometer, fourier transfer infra-red (ftir) type shimadzu prestige-21, and scanning electron microscope energy dispersive spectrometer (sem-eds) quanta 650. 2.2 synthesis and preparation of catalyst and characterization synthesis of ni/al-ldh was conducted according to lesbani et al. (2021) as follows: 0.75 m (ni(no3)2.6h2o) and 0.25 m (al(no3)2.9h2o) dissolved in 100 ml of distilled water, stirred for 2 h. then slowly added the mixture of naoh and na2co3 (ratio 2:1) to ph 10. the mixture was stirred for 17 h at 70°c, then ltered and dried. preparation ni/al-oxide was conducted 0.75 m (ni(no3) 2.6h2o) and 0.25 m (al(no3)2.9h2o) dissolved in 100 ml distilled water, stirred for 2 h. then slowly added the mixture of naoh and na2co3 (ratio 2:1) to ph 10. the mixture was stirred for 17 h at 70°c then added tio2/zno (ratio 1:1), shakenfor3h. themixturewasadded150ml0.37mnaoh, shaken for 17 h at 70°c, ltered, dried, and then calcinated at 300°c for 7 h. 2.3 oxidative desulfurization of dibenzothiophene dibenzothiophene with the concentration of 500 ppm was prepared in n-hexane and transferred to a two-pronged catalytic reaction ask. the ask is connected to a condenser to prevent evaporation of n-hexane. 0.25 g catalysts (ni/al-oxide) followed byadding1 mlof 30% hydrogen peroxide. the reaction was observed per 10 minutes time interval through extraction with acetonitrile followed by measuring using a uv-visible spectrophotometer at 235 nm. the percentage conversion of dbt followed the equation: %conversion of dbt = (c0,dbt − cf,dbt) c0,dbt × 100 where, c0,dbt and cf,dbt are the initial and nal concentrations of dbt, respectively. the process of optimizing the oxidative desulfurization of dbt was carried out with variations in time (10-60 min), uv-vis spectrum (220-250 nm), the dosage of catalyst (0.05-1 g), temperature (30-50°c), solvent (n-pentane, n-hexane, and n-heptane), acidity test, heterogeneous test, and reusability. reusability of catalyst is carried out by centrifugation of the reaction mixture after 1 h to recover the ni/al-oxide catalyst. the catalyst was washed with n-hexane several times, dried, and reused in the desulfurization of dbt. 3. results and discussion xrd powder diraction of ni/al-ldh, tio2, zno, ni/altio2, and ni/al-zno is shown in figure 2. xrd peaks of ni/al-ldh were analyzed from the jcpds no. 15-0087 (chen et al., 2022). ni/al-ldh peaks were detected at 2\= 11.48°(003), 23.30°(002), 35.03°(311), and 61.40°(013) (see © 2022 the authors. page 386 of 391 ahmad et. al. science and technology indonesia, 7 (2022) 385-391 figure 2a). the diraction peaks at 2\= 11.48°(003) and 61.40°(013) indicate crystal planes of ni/al-ldh (xie et al., 2021). figure2bshowndiractionoftio2 at2\=25.59°(101), 37.09°(004),48.16°(200),54.03°(211),55.26°(105), and62.29° (204). figure 2c shown diraction of zno at 2\= 31.75°(100), 34.41°(002),36.24°(101),47.52°(002),56.56°(110), and62.84° (103). tio2 and zno followed jcpds no. 73-1764 and 36-1451, respectively (basnet et al., 2019). the structure of ni/al-ldh, tio2, and zno in composite ni/al-tio2 and ni/al-zno was consistent, which also indicated that the preparation of composite did not change the form of precursors (see figures 2d and 2e). figure 2. xrd powder diraction of ni/al-ldh (a), tio2 (b), zno (c), ni/al-tio2 (d), and ni/al-zno (e) ftir spectra of ni/al-tio2 and ni/al-zno absorption band at 3398, 1639, 1339, 832, 731, and 682 cm−1 (see figures 3d and 3e). an absorption band at 3398 cm−1 was the o-h stretching vibrations in the hydroxyl layer (normah et al., 2021; palapa et al., 2021). 1639 and 1339 cm−1 as h-o-h and no3− stretching from ni/al-ldh (lv et al., 2022). the peaks at 832, 731, and 682 cm−1 can be assigned metal oxide in ni/al-ldh, tio2, and zno (intachai et al., 2021). table 1. eds of catalysts element ni/al-ldh (%wt) ni/al-tio2 (%wt) ni/al-zno (%wt) ni 33.9 20.7 15.6 al 5.2 3.1 13.9 ti 29.3 zn 18.2 o 43.2 34.8 27.2 figure 4 shows the sem image and eds of ni/al-ldh, ni/al-tio2, and ni/al-zno. sem image investigated the morphology of catalysts at 2500 times magnication. the catalysts have an irregular structure, tio2 and zno adhere figure 3. ftir spectrum of ni/al ldh (a), tio2 (b), zno (c), ni/al-tio2 (d), and ni/al-zno (e) to the surface of ni/al-ldh. eds analysis in table 1 shows the ni, al, ti, zn, and o atom percentages. ti and zn atoms appearaftercomposited intoni/al-tio2 andni/al-zno.the percent mass of ti and zn at 29.3% and 18.2%, respectively. thus, preparation of ni/al-tio2 and ni/al-zno has been a success. figure 4. sem image and eds of ni/al-ldh (a), ni/altio2 (b), and ni/al-zno (c) the acidity test was carried out using the gravimetric method with pyridine as the adsorbate base. pyridine has a large size causing bonding to occur only on the surface. the results of the determination of the acid site for each catalyst are shown in table 2. ni/al-ldh increased after being composited with tio2 and zno. the acidity of ni/al-ldh, tio2, zno, ni/altio2, and ni/al-zno were 0.148, 0.298, 0.782, 0.714, 0.184 © 2022 the authors. page 387 of 391 ahmad et. al. science and technology indonesia, 7 (2022) 385-391 mmol/gram, respectively. the increase in the acidity of ni/alldh, because it has been reduced, will lack electrons so that it has a higher ability to absorb pyridine. acid sites of catalysts are polyacid to convert dbt into dbt-sulfone (trisunaryanti et al., 2021). table 2. acidity of catalyst catalyst acidity (mmol/g) ni/al-ldh 0.148 tio2 0.298 zno 0.782 ni/al-tio2 0.714 ni/al-zno 0.184 figure 5. prole of desulfurization by time over composite catalysts the catalytic oxidative desulfurization of dbt is strongly inuenced by time. the eect of the desulfurization time of dbt is displayed in figure 5. the catalytic data showed a long reaction time was directly proportional to the high %conversion of dbt (muhammad et al., 2018). the optimum reaction time was 30 min and the percentage conversion of dbt on ni/al-ldh, tio2, zno, ni/al-tio2, and ni/al-zno were 99.44%, 91.92%, 95.36%, 99.88%, and 99.90%, respectively. the composite increases the ability of the catalyst in the desulfurization of dbt. in this study, ni/al-zno is better than ni/al-tio2 in conversion of dbt. the dbt that appeared in the acetonitrile phase was rapidly oxidized and converted to dbt-sulfone after extraction. uv-vis spectrum of oxidative desulfurization dibenzothiophene by composite catalysts is shown in figure 6. uv-vis spectrum used wavelength 220-250 nm. the absorbance of dbtat 235 nm decreased with increasing desulfurization time. the decrease in absorbance gradually indicates the concentration of dbt is decreasing. at 30 min, %conversion of dbt figure 6. uv-vis spectrum of oxidative desulfurization dibenzothiophene by composite catalysts >90% with the most signicant reduction indicated by ni/alzno catalyst. the eect of the dosage of catalyst is presented in figure 7. generally, a higher catalyst dosage will provide more opportunities for interaction between the active site of the catalyst and the dbt (ye et al., 2020). however, in contrast to this study, the optimum dosage for all catalysts was 0.25 g. a higher catalyst dosage will increase the active site of the catalyst while competing with oxidant molecules (subhan et al., 2019). therefore, increasing the catalyst dosage can reduce the %conversion of dbt. percentage of desulfurization order of dbt: ni/al-zno > ni/al-tio2 > ni/al-ldh > zno > tio2. figure 7. eect of catalyst dosage on desulfurization of dibenzothiophene figure 8 shows the eect of temperature catalytic oxidative desulfurization of dbt. the catalytic data shows that high temperature is directly proportional to the high %conversion of dbt. desulfurization of dbt using h2o2 is better at high temperatures by converting dbt to dbt-sulfone (fraile et al., 2016; lesbani et al., 2015). desulfurization of dbt at 50°c is better than at 30°c and 40°c. percentage of desulfurization © 2022 the authors. page 388 of 391 ahmad et. al. science and technology indonesia, 7 (2022) 385-391 orderof dbt: ni/al-zno > ni/al-tio2 > ni/al-ldh > zno > tio2. the fuel oil is operated at 60-70°c to overcome dierent oxidant dissociation energies. therefore, this study is superior because the temperature is lower with the same eciency. the eect of solvent was carried out to determine the best solvent in the oxidative desulfurization of dbt. n-pentane, n-hexane, and n-heptane were used as dbt solvents. the solvent eect shows that n-hexane is better at desulfurizing dbt than n-pentane and n-heptane. the results are compiled in figure 9 showing the desulfurization of dbton ni/al-zno > ni/al-tio2 > ni/al-ldh > zno > tio2. figure 8. eect of various temperatures on desulfurization of dibenzothiophene using composite catalysts figure 9. eect of solvent on desulfurization of dibenzothiophene by composite catalysts figure 10 shows the heterogeneous test of catalyst. heterogeneous test the catalyst to determine whether the catalyst is homogeneous or heterogeneous. homogeneous catalysts are soluble in the reactants/products of the reaction, while heterogeneous catalysts are insoluble. the heterogeneous test was carried out by desulfurization of dbt at 50°c for 10 min, the catalyst and dbt solution were separated. dbt solution continued with desulfurization process for 20-30 min. the unchanged dbt concentration indicates that ni/al-ldh, tio2, zno, ni/al-tio2, and ni/al-zno are truly heterogeneous system. the advantage of heterogeneous catalysts is that can be used for reusability (vallés-garcía et al., 2020). figure 10. heterogeneous test of catalyst reusability of catalysts is very inuential for the industry to save operating costs (song et al., 2021). reusability is suitable for ni/al-ldh, tio2, zno, ni/al-tio2, and ni/al-zno catalysts because they are heterogeneous. figure 11 shows the good reusability of catalyst. after 3 times catalytic reactions, the conversion of dbt still retains more than 80%, even ni/altio2 and ni/al-zno composites still 97.79% and 98.99%, respectively. ftir analysis was carried out to investigate changes in the structure of the catalyst after the reusability process. the new peak appearing at 1200 cm−1 is sulfone. figure 12 shows that the ftir ni/al-tio2 has undergone structural changes, while ni/al-zno is stable in reusability process. figure 11. reusability of catalyst © 2022 the authors. page 389 of 391 ahmad et. al. science and technology indonesia, 7 (2022) 385-391 figure 12. ftir spectrum of composites ni/al-tio2 (a), ni/al-zno (b) before and after desulfurization of third cycle 4. conclusions in the present study, composite layer double hydroxide-metal oxide (ni/al-tio2 and ni/al-zno) was successfully prepared and used as catalyst of oxidative desulfurization of dibenzothiophene. the acidity of ni/al-ldh increased after being composited with tio2 and zno. the optimum reaction time, dosage catalyst, and temperature were 30 min, 0.25 g, and 50°c, respectively, and n-hexane as a solvent. the percentage conversion of dibenzothiophene on ni/al-ldh, tio2, zno, ni/al-tio2, and ni/al-zno were 99.44%, 91.92%, 95.36%, 99.88%, and 99.90%, respectively. the catalysts are heterogeneous system and the advantage is that can be used for reusability. after 3 times catalytic reactions, the conversion of dibenzothiophene still retains more than 80%, even ni/al-tio2 and ni/al-zno composites still 97.79% and 98.99%, respectively. 5. acknowledgement authors thank universitas sriwijaya for funding this research through dipa of public service agency of universitas sriwijaya, hibah profesi sip dipa-023.17.2.677515/2022 on december 12, 2021 in accordance with the rector degree number 0111/un9.3.1/sk/2022 on april 28, 2022. we acknowledge research center of inorganic materials and complexes fmipa universitas sriwijaya for instrumental analysis and fruitful discussion. references abedini, f., s. allahyari, and n. rahemi (2021). oxidative desulfurization of dibenzothiophene and simultaneous adsorption of products on biobr-c3n4/mcm-41 visiblelight-driven core–shell nano photocatalyst. applied surface science, 569; 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121758 ye, j., j. wen, d. zhao, p. zhang, a. li, l. zhang, h. zhang, and m. wu (2020). macroporous 3d carbon-nitrogen (cn) conned moox catalyst for enhanced oxidative desulfurization of dibenzothiophene. chinese chemical letters, 31(10); 2819–2824 zeng, x., x. xiao, y. li, j. chen, and h. wang (2017). deep desulfurization of liquid fuels with molecular oxygen through graphene photocatalytic oxidation. applied catalysis b: environmental, 209; 98–109 zhu, x., c. chen, q. wang, y. shi, d. o’hare, and n. cai (2019). roles for k2co3 doping on elevated temperature co2 adsorption of potassium promoted layered double oxides. chemical engineering journal, 366; 181–191 © 2022 the authors. page 391 of 391 introduction experimental section chemicals and instrumentation synthesis and preparation of catalyst and characterization oxidative desulfurization of dibenzothiophene results and discussion conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper hydrochar and humic acid as template of znal layered double hydroxide for adsorption of phenol muhammad badaruddin1, nur ahmad2, erni salasia fitri3, aldes lesbani2,4, risfidian mohadi1,4* 1magister programme graduate school of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia2graduate school of mathematics and natural sciences, faculty of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia3magister programme in environment management, sriwijaya university, palembang, south sumatera, 30139, indonesia4research center of inorganic materials and coordination complexes, faculty of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia *corresponding author: risfidian.mohadi@unsri.ac.id abstractthe adsorbents potential znal-ldh, znal-hydrochar, and znal-humic acid were prepared using the coprecipitation method. theadsorbents were characterization by xrd, ftir, and bet analysis. xrd peaks of znal-ldh at 10.29°, 20.07°, 29.59°, 32.12°, 34.02°,48.06°, and 60.16°. the ftir absorption peak was observed at 3400-3500 cm−1, 1600-1700 cm−1, 1381 cm−1, 1000 cm−1,500-700 cm−1. all adsorbents exhibited n2 adsorption-desorption isotherms type iv classified as a mesoporous structure (poresize= 2-50 nm). the surface areas of composites were higher than ldh and following order: znal-hydrochar > znal-humic acid >znal-ldh. the kinetic parameter showed the pseudo-second-order kinetics model. the maximum adsorption capacity of znal-ldh,znal-hydrochar, and znal-humic acid were 48.077 mg/g, 90.090 mg/g, 94.340 mg/g, respectively; with freundlich isothermmodel. reusability after 5 times of znal-ldh, znal-hydrochar, and znal-humic acid in the range 49.81-0.890%, 95.92-9.84%, and70.02-5.72%, respectively. the adsorbent can be used up to 3 times. keywordshydrochar, humic acid, ldh, adsorption, phenol, regeneration received: 21 july 2022, accepted: 8 october 2022 https://doi.org/10.26554/sti.2022.7.4.492-499 1. introduction water is a basic human need to carry out activities. drinking water used must meet physical, chemical, and biological requirements. recently, rivers as water sources have been polluted by various kinds of waste, ranging from household and industrial to domestic waste (selvanathan et al., 2017). the waste is not handled correctly, so the water becomes polluted (chaari et al., 2020). one of the most dangerous wastes for the aquatic environment is phenol waste. several industries that have the potential to produce phenol waste include the petroleum rening, textile, gas, pharmaceutical, and petrochemical industries, coal processing, pharmaceuticals, polymer resins, pesticides, and household industries that produce liquid phenol waste (desmiarti et al., 2019; zhang et al., 2021). phenol is a dangerous organic compound with a high level of toxicity, which can cause harm to humans and biota (de la luz-asunción et al., 2015; dehbi et al., 2020; dehmani et al., 2021; girish and ramachandra murty, 2014) and accumulates in the environment. the limit of phenol concentration is 1.0 mg/l in water (xie et al., 2020). thus, developing an eective treatment to removal of phenol is necessary before being discharged to environment. various methods have been proposed for phenol wastewater treatment, including oxidation, membrane separation, biodegradation, ion exchange, and adsorption (tshemese et al., 2021). adsorption is one technique for removal of phenol because it is fast, cost-eective, easy handling, regeneration, high selectivity, and high eciency(badhai et al., 2020; ho and adnan, 2021). one of the materials used forwater treatment in the adsorption process is layered double hydroxide (ldh). this material has become a material that has been widely developed because of its uniqueness and good absorption. its application in water treatment as an adsorbent has excellent potential due to its low cost, exchangeable anionic features, and large surface area (bouteraa et al., 2020; zubair et al., 2021). according to vithanage et al. (2020), ldh is adsorbent in water treatment applications to remove organic, inorganic species, dyestus, and toxic metal contaminants. rathee et al. (2019) reported thatldh,whichwasappliedasanadsorbent, had limitations in https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.492-499&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.492-499 badaruddin et. al. science and technology indonesia, 7 (2022) 492-499 the regeneration process. therefore, the double-layerhydroxyl needs to be modied with a carbon-based support material to form a composite. layered double hydroxide nial, znal, and mgal composited with carbon-based materials such as chitosan were eectively to remove congo red, and the ability of the composite to be used repeatedly was stable until the seventh cycle in the regeneration process (siregar et al., 2021). based on the literature, it can be concluded that carbon-based supporting materials to form composites, such as hydrochar and humic acid, are suitable for use in layered double hydroxide. according to zubair et al. (2021), layered double hydroxide modied with carbon-based support material showed signicant results, namely an increase in physicochemical characteristics such as surface area, structural stability, functional groups, and the resulting adsorption characteristics. in this study, the synthesis of znal-ldh using the coprecipitation method and the preparation of znal composites with hydrochar and humic acid were carried out. the synthesized and prepared materials were characterized using x-ray diraction (xrd), fourier transform infra-red (ftir), and brunauer emmet teller (bet). furthermore, the material will beappliedasanadsorbent toadsorbphenolbystudyingvarious parameters including ph, contact time, temperatures, initial concentration, and regeneration. 2. experimental section 2.1 chemicals and instrumentation the chemicals were used, including zinc nitrate hexahydrate (zn(no3)2.6h2o),aluminumnitratenonahydrate (al(no3)3. 9h2o), sodium carbonate (na2co3), humic acid, hydrochar, hydrogenchloride (hcl), distilledwater(h2o),sodiumhydroxide(naoh),phenol (c6h5oh),4-aminoantipyrine(c11h13n3 o), potassium hexacyanoferrate(iii) (k3[fe(cn)6]), and acetate buer solution (ch3coona) ph 10. instrumentation was used in this study, including x-ray diraction (xrd), brunauer emmet teller (bet), and fourier transform infrared (ftir). 2.2 synthesis of znal-ldh znal-ldh synthesis was carried out with 100 ml zn(no3)2. 6h2o 0.75 m mixed with 100 ml al(no3)3.9h2o 0.25 m, then dripped into 50 ml naoh 2 m solution (mohadi et al., 2022). the mixture was adjusted to ph 10, then stirred for 20 h at 353 k. after stirring, the precipitate was ltered and rinsed using distilled water to remove impurities. the precipitate was dried using an oven. 2.3 preparation of znal-hidrochar and znal-humic acid znalcompositeswerepreparedusingthecoprecipitationmethod with constant ph. a total of 15 ml of 0.75 m zn solution and 15 ml of 0.25 m al solution were mixed, and the ph was adjusted to ph 10. the mixture was stirred for 1 h until homogeneous, and a gel was formed, then 3 g of humic acid/hydrochar was added. the solution was kept at 353 k for 3 days. the precipitate from the preparation was ltered and dried using an oven. 2.4 adsorption of phenol phenol is a colorless solution, so it must be complexed before being measured using a uv-vis spectrophotometer (xie et al., 2020). 1 ml of phenol solution was put in a beaker, then 0.1 ml of 4-aminoantipyrine 2% was added, 0.1 ml of potassium hexacyanoferrate (iii) 8%, 1 ml of ph 10 buer solution, and 3 ml of distilled water were added. then homogenized and allowed to stand for 5 min. the maximum wavelength of phenol after complexing is 510 nm. 2.5 eect of ph adsorbent (0.05 g) was put into a 100 ml beaker lled with 50 ml of phenol solution, each at a concentration of 20 mg/l with a variation of ph 2-11 with stirring for 2 h. 2.6 eect of contact time adsorbent (0.05 g) was added to 50 ml of 20 mg/l phenol solution, then stirred with variations contact time (0-180 min). the adsorbent was separated from the phenol solution. 2.7 eect of initial concentration and temperatures adsorbent (0.05 g) was added 50 ml of phenol solution with various initial concentrations (10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l and 50 mg/l and various temperatures (303 k, 313 k, 323 k, and 333 k). the solution was stirred for 2 h. 2.8 reusability of adsorbents the adsorption process for phenol is carried out before being used repeatedly as an adsorbent. after that, the desorption of phenol solution using an ultrasonic device. the regeneration process is carried out by adding 50 mg/l of 50 ml phenol solution to adsorbent that has gone through the desorption process. 3. result and discusssion figure 1. xrd diractogram of adsorbents © 2022 the authors. page 493 of 499 badaruddin et. al. science and technology indonesia, 7 (2022) 492-499 xrd patterns of znal-ldh, znal-hydrochar, and znalhumic acid is displayed in figure 1. znal-ldh peaks at 10.29°, 20.07°, 29.59°, 32.12°, 34.02°, 48.06°, and 60.16° were indexed to (003), (006), (101), (012), (015), (107), and (110) corresponding to jcpds no 05-0669 (elhalil et al., 2017). the peaks at 10.29° and 60.16° indicated the anion in the interlayer of layered double hydroxide. after znal-ldh was composited with hydrochar and humic acid, the peak at 20.3° indicated the humic acid, while the diraction peaks of hydrochar at peaks 18.0°. the characteristic peaks of the constituents znal-ldh, hydrochar, and humic acid indicated that the preparation of the composite has been successful. figure 2. ftir spectra of adsorbents figure 2 shows the ftir spectra of znal-ldh, znalhydrochar, and znal-humic acid. the absorption peak was observed at 3400-3500 cm−1 assigned to o-h vibration from water in ldh (li et al., 2020). the peak at 1600-1700 cm−1 indicated vibration of -oh and carbonyl (coo) (rashid et al., 2017). the peak at 1381 cm−1 corresponds to n-o from nitrate (palapa et al., 2021). the new peak around 1000 cm−1 at znal-hydrochar and znal-humic acid indicated c-o stretching from hydrocharand humic acid (lu et al., 2019; shao et al., 2022). the peak at 500-700 cm−1 assigns to metal-oxide in ldh (ahmad et al., 2022b). textural properties of znal-ldh, znal-hydrochar, and znal-humic acid give in figure 3. all adsorbents exhibited n2 adsorption-desorption isotherms type iv classied as a mesoporous structure (pore size = 2-50 nm) (cao et al., 2022). in line with the data in table 1, the pore size of adsorbent is 4-27 nm. the surface areas of composites were higher than ldh and were in the following order: znal-hydrochar > znal-humic acid > znal-ldh. the pore volume of znalhydrochar was higher than znal-humic acid and znal-ldh. thus, the surface area is directly proportional to the pore volume. the eect of ph in adsorption phenol was displayed in figure 4. ph is one of the key parameters in adsorption. ph figure 3. n2 adsorption-desorption isotherms figure 4. eect of ph optimum of znal-ldh, znal-hydrochar, and znal-humic acid was at ph 4, 2, and 2, respectively. under acidic conditions, phenol adsorption is better because the phenol molecules do not dissociate, thereby reducing electrostatic repulsion and hydrogenbondingbeing theprimaryinteraction (asnaouietal., 2022). kinetic parameters adsorption of phenol is shown in figure 5. the pseudo-rst-order (pfo) and pseudo-second-order (pso) kinetic models were determined through the highest linear regression value. based on table 2, znal-ldh, znalhydrochar, and znal-humic acid followed the pso kinetics model (r2 closer to 1). pso model assumes that the active site of the adsorbent is available more than the possible bond between the adsorbent and the adsorbate that occurs (de farias et al., 2022). determination isotherm model seen the linear regression value (r2) which is closer to 1. znal-ldh, znal-hydrochar, and znal-humic acid tend to follow the freundlich isotherm model because the r2 value is closer to 1 compared to the © 2022 the authors. page 494 of 499 badaruddin et. al. science and technology indonesia, 7 (2022) 492-499 figure 5. eect of contact time table 1. bet analysis of adsorbents adsorbents surface area pore size pore volume (m2/g) (nm), bjh (cm3/g), bjh znal-ldh 1.968 27.687 0.006 znal-hydrochar 29.874 24.420 0.042 znal-humic acid 16.425 4.811 0.039 table 2. kinetics parameters the adsorption process kinetic parameters adsorbents parameter znal-ldh znalhydrochar znal-humic acid pfo qeexp (mg/g) 46.845 52.228 48.627 qecalc (mg/g) 48.228 44.627 41.295 k1 (min−1) 0.033 0.034 0.034 r2 0.965 0.989 0.969 pso qeexp (mg/g) 46.845 52.228 48.627 qecalc (mg/g) 56.644 59.524 56.497 k2 (min−1) 0.001 0.001 0.001 r2 0.993 0.993 0.986 © 2022 the authors. page 495 of 499 badaruddin et. al. science and technology indonesia, 7 (2022) 492-499 table 3. isotherm parameters the adsorption process adsorbents langmuir freundlich t (k) qmax kl r2 n kf r2 znal-ldh 303 20.492 0.167 0.974 5.149 15.765 0.994 313 48.077 0.063 0.844 1.866 5.338 0.847 323 43.487 0.140 0.930 2.482 9.643 0.822 333 42.553 0.332 0.984 3.221 15.191 0.855 znal-hydrochar 303 27.027 0.019 0.961 1.989 6.703 0.947 313 85.470 0.012 0.956 1.164 2.078 0.957 323 75.188 0.038 0.7984 1.473 4.248 0.954 333 90.090 0.071 0.8516 1.900 7.579 0.943 znal-humic acid 303 26.882 0.078 0.969 3.837 12.552 0.989 313 44.444 0.053 0.944 1.678 4.281 0.975 323 64.935 0.049 0.900 1.616 5.018 0.962 333 94.340 0.077 0.911 1.987 8.468 0.968 table 4. several adsorbents to adsorption of phenol adsorbent qmax (mg/g) references lignite 6.216 (liu et al., 2021) tea waste biomass 7.62 (gupta and balomajumder, 2015) mag-ctab-kh550 56.13 (ge et al., 2018) bentonite 23.64 (ahmadi and igwegbe, 2018) fe-biochar 39.23 (dong et al., 2021) zncl2-bfac 17.02 (sathya priya and sureshkumar, 2020) claried sludge from basic oxygen furnace 1.052 (mandal and das, 2019) 𝛼-fe2o3 21.93 (dehmani and abouarnadasse, 2020) activated carbon 75.81 (da silva et al., 2022) znal-ldh 48.077 this study znal-hydrochar 90.090 this study znal-humic acid 94.340 this study table 5. adsorption thermodynamic parameter adsorbents δh (kj/mol) δs (j/k.mol) δg (kj/mol) r2 303 k 313 k 323 k 333 k znal-ldh 51.180 0.171 -0.586 -2.294 -4.003 -5.711 0.985 znal-hydrochar 33.152 0.110 -0.224 -1.326 -2.427 -3.529 0.993 znal-humic acid 33.821 0.133 -0.488 -1.620 -2.752 -3.885 0.988 © 2022 the authors. page 496 of 499 badaruddin et. al. science and technology indonesia, 7 (2022) 492-499 langmuir isotherm model (see table 3). freundlich isotherm assumes that the adsorption process is physisorption and occurs in multilayers (jain et al., 2022). the maximum adsorption capacity of znal-ldh, znal-hydrochar, and znal-humic acid were 48.077 mg/g, 90.090 mg/g, 94.340 mg/g, respectively. the comparison of adsorption capacity with other adsorbents can be seen in table 4. the thermodynamic parameters determined in the adsorption includeenthalpy(δh),entropy(δs),andgibbs freeenergy (δg) as presented in table 5. the enthalpy (δh) is positive in the range of 31-51 kj/mol, this indicates that the reaction that occurs is endothermic (dehmani et al., 2020). the entropy (δs) is positive in the range of 0.110 0.171 j/mol.k, this indicates that the degree of disorder is small during the adsorption process (zhang et al., 2022). the gibbs free energy (δg) is negative, indicating that adsorption of phenol is spontaneous (ahmad et al., 2022a). figure 6. reusability of adsorbents reusabilityofadsorbent is therepeateduseof theadsorbent byremovingtheadsorbatefromtheadsorbent (quetal.,2022). based on figure 6, reusability after 5 times of znal-ldh, znal-hydrochar, and znal-humic acid in the range 49.810.890%, 95.92-9.84%, and 70.02-5.72%, respectively. the percentageofreusabilitydecreaseswith thefrequentadsorption process. the adsorbent can be used up to 3 times. 4. conclusion in summary, znal-ldh, znal-hydrochar, and znal-humic acid were successfully prepared. the adsorbents 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(2022). hydroxyl-functionalized hypercrosslinked polymers with ultrafast adsorption rate as an ecient adsorbent for phenol removal. microporous and mesoporous materials, 336; 111836 zubair, m., i. ihsanullah, h. a. aziz, m. a. ahmad, and m. a. al-harthi (2021). sustainable wastewater treatment by biochar/layered double hydroxide composites: progress, challenges, and outlook. bioresource technology, 319; 124128 © 2022 the authors. page 499 of 499 introduction experimental section chemicals and instrumentation synthesis of znal-ldh preparation of znal-hidrochar and znal-humic acid adsorption of phenol effect of ph effect of contact time effect of initial concentration and temperatures reusability of adsorbents result and discusssion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper pattern recognition using multiclass support vector machine method with local binary pattern as feature extraction nursyiva irsalinda1*, sugiyarto surono1*, indah dwi ratna sary1 1department of mathematics, ahmad dahlan university, yogyakarta, 55191, indonesia *corresponding author: nursyiva.irsalinda@math.uad.ac.id, sugiyarto@math.uad.ac.id abstractpattern recognition is a scientific discipline usually used to classify objects into a number of categories or classes through a featureextraction method applied to recognize an object accurately. meanwhile, local binary pattern (lbp) is a texture analysis methodwhich uses statistical and structural models for feature extraction. moreover, a support vector machine (svm) method is normallyused to solve non-linear problems in high dimensions to obtain an optimal solution by finding the best hyperplane through themaximizing of the margin between two data classes. pattern recognition in paintings using machine learning has never been done inany research. meanwhile it is very important in the future to be able to serve as a verification system for novelty works of art at thestage of filing for intellectual property rights. therefore, this study aimed to apply pattern recognition with lbp feature extractionmethod and multiclass svm classification method to classify the flow of several classes of painting works including expressionism,fauvism, naturalism, realism, and romanticism. the best evaluation results using this method were obtained in the training andtesting data combination of 90:10 with an accuracy rate of 83%. therefore, it can be concluded that machine learning in patternrecognition of painting works can be applied. keywordspattern recognition, local binary pattern, support vector machine, multiclass svm received: 19 january 2022, accepted: 23 april 2022 https://doi.org/10.26554/sti.2022.7.3.269-274 1. introduction technological developments have made data become one of the important components in every human activity. these data can be numeric, categorical, text, images, and others but the most widely used form in recent times is the images which are usually processed to produce a good identication process. meanwhile, an important method usually used in solving problems in image processing is pattern recognition which is a scientic discipline designed to classify objects into a number of categories or classes (theodoridis, 2009). moreover, the numerical pattern recognition which is a statistical approach involves using multidimensional data vector as input where each component is called a feature. the numerical pattern recognition observed to be increasingly used in decision-making processes. furthermore, a pattern recognition process through feature extraction method such as the local binary pattern method is needed to recognize an object accurately. local binary pattern (lbp) is a texture analysis method which uses statistical and structural models for feature extraction (amat et al., 2017; nugraha et al., 2019). it works by applying a threshold to the surrounding pixels based on the pixels being observed (galshetwar et al., 2017; sharma et al., 2020) and also reported to be widely used in applications involving image texture capture and classication (kaewchote et al., 2018; prashanth et al., 2020). some of its advantages includes being xed to changes in light intensity from the same object and accuracy in recognizing an object (susanto et al., 2018). moreover, it can also be implemented easily and fairly quickly for feature extraction using low computational processes (amat et al., 2017). classication is one of the supervised learning methods in data mining. it is usually used to nd a model or function of a data set by grouping it into classes such that the data objects determined in each class label indicates they have the same characteristics or similar pattern (cervantes et al., 2020). the grouping process involves dividing the data into predetermined classes and assigning the classes according to the similarity in characteristics and the patterns in the words (styawati and mustofa, 2019). support vector machine (svm) was introduced by vapnik in 1995 is a method widely used in classifying supervised learning (ay et al., 2019; komarudin et al., 2020; wang and zhao, https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.269-274&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.269-274 irsalinda et. al. science and technology indonesia, 7 (2022) 269-274 2020; yin and yin, 2016). svm is formulated to solve nonlinear problems in high dimensions to obtain optimal solutions (li et al., 2020; liu et al., 2017; pramudita and musdholifah, 2020; styawati and mustofa, 2019; tang et al., 2019). this methodnds thebesthyperplanebymaximizingthemarginbetween two classes of data (komarudin et al., 2020). meanwhile, the margin is dened as the distance between the hyperplane and the support vector which is the closest data from the class to the hyperplane. it is important to note that svm uses a trick kernel function to calculate data with non-linear problems in order to obtain classication results with a good level of accuracy. however, it is sensitive to noise and outliers and also reported is less ecient in obtaining complex models for large-scale data sets (cervantes et al., 2020). meanwhile, some of its benets include the ability to minimize errors and higher accuracy when compared with other classications methods (utami et al., 2021). pattern recognition and svm classication methods have been widely used in previous studies. for example, dias aziz pramudita and aina musdholifah added a parameter optimization process known as the gravitational search algorithm (gsa) to improve the accuracy of the svm method in the thyroid nodule classication process (pramudita and musdholifah, 2020). l. jerlin rubini and eswaran perumal also used the fruit fly optimization algorithm (ffoa) to select the best features in medical data which were later processed using the multiclass svm method for classication (jerlin rubini and perumal, 2020). moreover, diya wang and yixi zhao predicted the feelings of investors towards stock market news using the svm method in order to make decisions with a high level of accuracy (wang and zhao, 2020). study about svm also developed to enhance age invariant face recognition performance based on gender classication (nayak and indiramma, 2021) while mayur succeeded in showing that cnn-ecoc produced higher accuracy than ordinary cnn classication (bora et al., 2020). another research found a higher accuracy of performance for multiclass svm method when compared with svm method (alita et al., 2020). from the studies related to pattern recognition that have been described. there has been no research on the multiclass svm method that uses lbp as its feature extraction. by looking at the advantages of lbp and in order to nd a method with better results, the researchers combined the multiclass svm method with lbp to classify pattern recognition. the case study adopted in this research is the classication of paintings into ve classes, namely expressionism, fauvism, naturalism, realism, and romanticism. this case study was appointed because pattern recognition in paintings using machine learning has never been done in any research. meanwhile it is very important in the future to be able to serve as a verication system for novelty works of art at the stage of ling for intellectual property rights. this present study, therefore, uses the multiclass support vector machine (msvm) method to classify pattern recognition using the lbp method for feature extraction. the aim was to determine the eectiveness of applying these methods in classifying the ow in a painting. 2. materials and methods 2.1 pattern recognition patternrecognition isadisciplineusuallyusedtoclassifyobjects intoanumberofcategoriesorclasses (theodoridis,2009). the object can be an image, a signal waveform, or any type of measurement that needs to be classied. this means pattern recognition is an important part of a system for decision-making purposes. 2.2 local binary pattern method the local binarypattern method was rst introduced bytimo ojala in 1994 as a texture analysis method which uses statistical and structural models (ojala et al., 2000). it also has the ability to compare the gray values of the surrounding pixels (abbas et al., 2019; agbele et al., 2019; ali et al., 2017; kwabena et al., 2020; muqeet and holambe, 2019; vidya and chandra, 2019). the basic lbp operator was congured using 8 pixels around a center pixel and the threshold of the nth surrounding pixel was through the gray value of the center pixel and the thresholding function. the binary code generated by this lbp was, therefore, used to represent the features of the center pixel ic. lbp(xc, yc) = n−1∑︁ n=0 s(in − ic)2n (1) s(x) = { 1, x ≥ 0 0, x < 0 (2) where xc = pixel width yc = pixel height s(x) = threshold function which is dened by (2) in = ambient pixels from the center ic = center pixel lbp is easy to implement, has lower computational level, does not require a long time for feature extraction (shiyam, 2019), xed to changes in light intensity from the same object, and accurate in recognizing an object (gonzalez, 2009). 2.3 support vector machine method support vector machine (svm) is one of the methods usually used classifying supervised learning and reported to be rst introduced by vapnik in 1995 (ay et al., 2019; komarudin et al., 2020; wang and zhao, 2020; yin and yin, 2016) to solve non-linear problems at high dimensions (abbas et al., 2019; battineni et al., 2019) in order to obtain an optimal solution. the method nds the best hyperplane by maximizing the margin between two data classes. meanwhile, a hyperplane is dened as a line or eld separating the data between dierent classes while margin is the distance between the hyperplane and the support vector which acts as the closest data from the class to the hyperplane. © 2022 the authors. page 270 of 274 irsalinda et. al. science and technology indonesia, 7 (2022) 269-274 for example, the training data set d is dn = (x1, y1), (x2, y2), ..., (xn, yn), where d= b{(xi , yi)}ni=1, xi ∈ r d is the training data set while x1 is the input data and y1 ∈ (+1,-1) is a class label with an output value of +1 (positive) or -1 (negative). the main concept used in assigning the separator to a linear separable is the dot product between two vectors which is dened as wtx= σiwixi. where, w is the weighting vector and b is the bias. moreover, the separating hyperplane was used to divide the space into two classes as indicated in the following relationship. h(x) = wtxi + b + 0 (3) meanwhile, the separator function for the two classes is as follows wtxi + b ≥ +1 for yi = +1 and wtxi + b ≤ −1 for yi = −1 where, |b|| |w| | is the perpendicular distance of the dividing plane from the center of the coordinates and ||w|| is the euclidean distance (euclidean norm) from w. moreover, the quadratic programming (qp) problem was thestepusedindeterminingtheminimumpointbyconsidering the equation constraints. min w,b 1 2 ||w||2 (4) with constraint function yi (wxi + b) − 1 ≥ 0, i = 1, 2, ..., m itisalsopossible toresolvetheoptimizationproblemthrough the use of the lagrange multiplier as indicated in the following equation: l = 1 2 ||w||2 − n∑︁ i=1 𝛼i (yi ((wxi + b) − 1)) (5) where, 𝛼i is the lagrange multiplier which is zero or positive (𝛼i ≥ 0). the problem was, therefore, optimized by minimizing l to w and b and maximizing 𝛼i. the equation was later modied as follows with due consideration for the nature of the optimal point l= 0: condition 1 𝜕lp 𝜕w = 0 → w = n∑︁ i=1 𝛼iyixi (6) condition 1 𝜕lp 𝜕b = 0 → w = n∑︁ i=1 𝛼iyi = 0 (7) the substitution of w changed the equation into a lagrange duality max ld = n∑︁ i=1 𝛼i − 1 2 ∑︁ i, j 𝛼i𝛼 jyiyjxi · xj (8) condition 1 n∑︁ i=1 𝛼iyi = 0 condition 2 𝛼i ≥ 0, i = 1, 2, ..., n 2.4 kernel the support vector machine learning process to determine the support vectors depends on the dot product of the data in the feature space i.e. φi(xi) ·φi(xj). it is, therefore, possible to replace this dot product calculations with trick kernel functions k(xi ,xj) which implicitly dene the transformation and formulated as follows: k(xi , xj) = φi (xi) · φ(xj) (9) one of the trick kernel functions commonly used in the general classication of support vector machines is radial basis function (rbf) which is presented as follows. k(xi , xj) = exp ( − ||xi − xj ||2 2𝜎2 ) (10) previous studies have alreadyshown that the radial basis function (rbf) kernel has a better accuracy rate than other kernels (caraka et al., 2017). therefore, it was applied in this research for classication using the multiclass support vector machine method. 2.5 multiclass svm the support vector machine (svm) method was rst introduced by vapink only to classify data into two classes. subsequent research has, however, been conducted to increase its ability to classify data for more than two classes. moreover, there are two approaches to solve svm problems for multiclass and the rst includes the combination of all data in an optimization problem while the second involves building a multiclass classier or several binary svms. the rst approach requires solving a more complex and computationally high optimization problem and this limits its development. meanwhile, the second such as "one-against-all" approach is usually used to implement multiclass svm. this one-against-all (oaa) method is usually used to determine the k binary svm models where k is the number of classes (chamasemani and singh, 2011; kumar and gopal, 2011). it also tests p l with all data from the class with label +1 and those from other classes with label -1. an example of a classication problem with ve classes and ve binary svms is presented on table 1. © 2022 the authors. page 271 of 274 irsalinda et. al. science and technology indonesia, 7 (2022) 269-274 table 1. oaa method yi= 1 yi= -1 hypothesis class 1 not class 1 f1(x)= (w1)x+b1 class 2 not class 2 f2(x)= (w2)x+b2 class 3 not class 3 f3(x)= (w3)x+b3 class 4 not class 4 f4(x)= (w4)x+b4 class 5 not class 5 f5(x)= (w5)x+b5 3. results and discussion this research used painting works data including expressionism, fauvism, naturalism, realism, and romanticism. a total of 420 images on ow of painting were obtained and these include 70 for expressionism, 100 for fauvism, 80 for naturalism, 70 for realism, and 100 for romanticism. these image data were later divided into training and testing samples at dierent combinations including 90:10, 75:25, 50:50, and 25:75. table 2. lbp value data value 0 1 2 3 4 5 . . . 255 image 1 833 117 99 79 126 49 . . . 937 image 2 676 86 272 85 86 12 . . . 807 image 3 754 110 96 76 95 42 . . . 920 ... ... ... ... ... ... ... . . . ... image 420 393 67 226 110 57 14 . . . 603 figure 1. prediction results and the actual data 3.1 result of feature extraction method lbp each of the images was resized and converted to a grayscale in the lbp to determine the pixel values at each point. these values were made into threshold and their binary values encoded to produce lbp values for all pixel points in the image. the nal result of the feature extraction is presented on a histogram and one image was discovered to have 256 values based on the frequency of occurrence from 0 to 255. these outputs are also indicated in the on table 2. the data from the lbp extraction process were used as the input for the classication conducted through the multiclass support vectormachine (msvm) using the radial basis function (rbf) kernel. the results of the prediction against the actual data for each of the proportions are, therefore, shown in the following graphic images: figure 1 shows the 90:10 combination produced predictions which are almost the same as the actual data. moreover, the classication results for each training and testing data combination were evaluated using a confusion matrix to determine the deviations in the prediction process and the ndings are presented as follows. figure 2. (a) confusion matrix generated by 90:10 partitioned data. (b) confusion matrix generated by 75:25 partitioned data. (c) confusion matrix generated by 50:50 partitioned data. (d) confusion matrix generated by 25:75 partitioned data figure 2 shows the correct prediction results are located in the diagonal part of the table. moreover, the performance of the msvm classication model was determined based on precision, recall, and accuracy as indicated in figure 3: figure 3. evaluation model on each data partition © 2022 the authors. page 272 of 274 irsalinda et. al. science and technology indonesia, 7 (2022) 269-274 figure 3 illustrates the evaluation classication that has been produced by the combination of the lbp method with msvm to classify the data of works of art in the form of painting. from the four partition combination experiments that is 90:10, 75:25, 50:50 and 25:75 the accuracy, precision and recall values are obtained as shown in figure 3. from the bar charts, it can be seen clearly that the data partition is 90:10 more has the highest value in terms of accuracy, precision and recall. while the 25:75 data partition has the lowest model evaluation value among the others. 4. conclusions data analysis and discussion showed that pattern recognition through local binary pattern feature extraction and multiclass support vector machine were used to classify works of art into ve classes which include expressionism, fauvism, naturalism, realism, and romanticism. it was discovered that the classication made by combining training and testing data at 90:10 had an accuracy rate of 83%, 75:25 had 81%, 50:50 had 81%, and 25:75 had 51%. therefore, the best evaluation of pattern recognition classication in this data case using multiclass support vector machine with local binary pattern as feature extraction were obtained through training and testing data combined at 90:10. based on the results of the study, it was concluded that the pattern recognition process using the local binary pattern method for feature extraction and the multiclass support vector machine method can be used to classify works of art into ve classes, namely expressionism, fauvism, naturalism, realism, and romanticism. therefore, this study needs to be further developed by adding more types of paintings to be used as a novelty verication system for works of art at the stage of ling intellectual property rights. 5. acknowledgment the author thanks to research and community service institute of ahmad dahlan university who give nancial support through ocial research scheme funding. references abbas, a. k., n. a. al-haideri, and a. a. bashikh (2019). implementing articial neural networks and support vector machines to predict lost circulation. egyptian journal of petroleum, 28(4); 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science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper investigation of the physical properties and droplet combustion analysis of biofuel from mixed vegetable oil and clove oil adhes gamayel1*, mohamad zaenudin1, m. n. mohammed2, eddy yusuf3 1department of mechanical engineering, faculty of engineering and computer science, jakarta global university, depok, west java, 16412, indonesia2mechanical engineering department, college of engineering, gulf university, sanad, 26489, the kingdom of bahrain3department of pharmacy, faculty of pharmacy, jakarta global university, depok, west java, 16412, indonesia *corresponding author: adhes@jgu.ac.id abstractthe study of vegetable oil used as fuel in conventional engines leads to problems like the low volatility and high viscosity. thisresearch aims to evaluate the droplet combustion characteristics that correlated with the density, viscosity, and the flash point of thebiofuel from mixed vegetable oil with clove oil. biofuels used in research are jatropha oil (cjo), kapok oil (kso), coconut oil (cco),and all biofuel mixed with clove oil in 5% basis volume. fuel properties that tested both biofuel and fuel mixture using the astmmethod are density (astm d1298), viscosity (astm d445), the flash point (astm d93). the droplet combustion experiment usedsuspended droplets placed in the junction of the k-type thermocouple and the ni-cr wire (as the coil heater) to heat the droplet untilthe combustion occurred. the result indicates that adding 5% clove oil in biofuel creates higher density, the viscosity decreasesuntil 10%, and the flash point decrease to 30%. droplet combustion results that adding 5% clove oil creating a more completecombustion process in cco than kso and cjo. higher viscosity in kso and cjo leads to eugenol and terpene (clove oil compound)trapping in the fuel droplet. due to eugenol and terpene having great volatility, they are evaporating rapidly leading to secondaryatomization and micro-explosion phenomena. keywordsbiofuel, vegetable oil, clove oil, micro-explosion, combustion received: 21 july 2022, accepted: 12 october 2022 https://doi.org/10.26554/sti.2022.7.4.500-507 1. introduction the issue of global warming and climate change continues to strengthen cause the demand for substitute fuel has increased. many researchers have been conducted studies to substitute diesel fuel with vegetable oils because of their advantages such as non-toxic and biodegradable (che hamzah et al., 2020). however, the demerit of vegetable oils for feasibility as diesel fuels are high viscosity and low volatility. high viscosity leads to poor fuel atomization and has a signicant eect on spray characteristics. subsequently, the rate of evaporation of fuel has been decreased and creates inecient mixing of oil with air that contributes to incomplete combustion and leads to carbon deposit formation on the crown piston, ring, and injector. misre, ignition delay, and poor cold engine start-up are the eect of a combination of high viscosity and low volatility of vegetable oils. to reduce the demerit of vegetable oil, they can be mixed with oil that has low viscosity and high volatility (al-abdullah et al., 2015). essential oil is a natural volatile oil that renewable resource and it is mostly used as additives in the pharmaceutical and cosmetic industries. it can be extracted from leaves, roots, buds, and petals using distillation (gad et al., 2021). the main compound of essential oil is aromatics which involves single or multiple rings which are planar and have a periodic order of a p orbitals having 4n+2𝜋 electrons, and each atom involved in the fragrant ring includes a p orbital (fu and turn, 2018). nowadays, the researcher is studying essential oil as blended fuel due to the equivalences in properties to conventional fuel. pine oil has some prominent fuel-related properties, such as lower viscosity, ash point, and boiling point than those of pure diesel (huang et al., 2019; vallinayagam et al., 2013). another essential oil, turpentine oil, could be implemented as additional fuel for implementation in diesel engine refers at many studies haveresulted inmuch-improvedperformancewhenturpentine oil has been used for up to 30% (jeevanantham et al., 2020). eucalyptus, tea tree oil, and orange have comparable values in basic fuel properties and higher surface tension than diesel fuel (rahman et al., 2019). the addition of clove oil which acts as an antioxidant to b20 has decreased viscosity, density, ash https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.500-507&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.500-507 gamayel et. al. science and technology indonesia, 7 (2022) 500-507 point, and caloric value and meet the astm standard for cold ow properties (jeyakumar and narayanasamy, 2019). to analyze combustion characteristics based on fuel components and properties, droplet combustion is a simple method thathavemodestutilization,andanattractiveanalysis (gamayel et al., 2020). the disruptive burn in multicomponent fuel droplets has been compared with the steady burn in monocomponent fuel (hoxie et al., 2014). many researchers have studied the single droplet combustion of vegetable oil in recent years. the jatropha oil change at various diameters of droplet, but it does not change the ignition temperature at various oil temperatures (wardana, 2010). ignition characteristics and burning behaviors from butanol in the range of 25-75% mixed with soybean oil were analyzed as a result of the microexplosion case in most violent at mixed butanol in 40% (hoxie et al., 2014). in an extended experiment, butanol, pentanol, and soybean oil were blended in the binary-ternary form and then examined as single droplet combustion (coughlin and hoxie, 2017). based on the previous study, a single droplet experiment and multicomponent analysis using essential oil as an addition to vegetable oil are rare. the correlation of molecule geometry and the motion of the molecule with properties and the combustion need to be observed. subsequently, an explanation of the ame geometry during micro-explosion needs to be studied. hence, this experiment aims to study the performance of mixed vegetable oil with clove oil in terms of basic fuel properties and single droplet combustion. 2. experimental section 2.1 materials vegetable oil used in this experiment was crude oil, namely jatropha oil (cjo), kapok seed oil (kso), and coconut oil (cco). clove oil was mixed with each vegetable oil in 5% basis volume with initial namely, cjo95c5, kso95c5, and cco95c5. the observation in basic fuel properties and droplet combustion between vegetable oil and its blend. they were prepared using the splash blending method and kept at room temperature for several days to observe any phase separation in the fuel blend. table 1. the chemical compound of clove oil compound % eugenol 63.74 cis-caryophyllene (c15h24) 26.32 caryophyllene 6.31 a-humulene 3.53 the chemical compound of clove oil taken from our previous study gamayel et al. (2020), shown in table 1 eugenol has the biggest compound with 63.74% in clove oil. eugenol has a structure consisting of aromatics and hydroxyl groups (-oh). phenol is one classication of eugenol where the primaryantioxidant which has a function to convert radical energy to become stable. an aromatics structure is a bulky structure composed of ring benzene. it leads to the density of aromatic compounds higher than diesel fuel and biofuel. aromatic promotes the adiabatic ame temperature (han, 2013). hydroxyl groups are atoms with electronegative and donors in hydrogen bond (lapuerta et al., 2015). a-humulene, cis-caryophyllene, and caryophyllene are classied as sesquiterpenes with volatile compounds, a strong odor, and an antioxidant. thevegetableoilcompositionfromtheliteratureandshown in table 2. according to fatty acid composition, both cjo and kso are unsaturated fatty acids, due to the high percentage of oleic acid and linoleic acid which have double carbon chains and bulky structures of the molecule. meanwhile, cco is a saturated fatty acid due to the highest compound is lauric acid which builds with 12-carbon atom a single chain. 2.2 methods 2.2.1 fuel physical properties density is an important quality indicator for automotive, marine, and aviation fuels. this number aects handling, storage, and combustion. density is expressed in units of grams per liter, dene as the relationship between the mass and volume of a liquid (atabani et al., 2013). it was found to relatively increase in density with the increase of unsaturation degree of vegetable oil (altaie et al., 2015). viscosity is an indication of a uid ability to owand it’s related to the cohesion forces among the molecule (conceição et al., 2005). it has a signicant eect on spray characteristics and takes a long time to mix with air. the measurement used leybold didactic viscometerapparatus with the standard of astm d445. this method determines of kinematic viscosity of a liquid both transparent or opaque. the ash point indicates the presence of a highly volatile and ammabilityproperties of fuel (atabani et al., 2013). the ash point also denes as a temperature that shows the rst ignition above the liquid of fuel (keshavarz and ghanbarzadeh, 2011). the measurement method used astm d93 with the closed cup ash point tester from leybold didactic. these test methods cover the determination of the ash point of petroleum products, but this standard also can use for vegetable oil in similar diesel engine implementation 2.2.2 droplet combustion the experimental setup was similar to the previous study by gamayel et al. (2020) were used the transformer, ni-cr wire, k-type thermocouple, syringe, data acquisition system, and camera. the hamilton microliter syringe was used to create a droplet in the volume range 0.5∼1 microliter. the use of syringes is dierent from the previous studydue to the dierent syringe materials leading to an easier practical handling of the droplet in junction thermocouple. digital single-lens reex camera at 25 fps (canon eos 4000d) used to record the ame evolution. the disruptive light has created the capture of ame shape and the color degradation of ame is unclear. besides that, the micro-explosion phenomena that describe in ’ame in ame’ can’t be captured. the disruptive light in ame © 2022 the authors. page 501 of 507 gamayel et. al. science and technology indonesia, 7 (2022) 500-507 table 2. fatty acid percentage fatty acid composition number of c cco (nakpong and wootthikanokkhan, 2010) kso (wirawan et al., 2014) cjo (meher et al., 2013) caprylic acid (c8:0) 3.35 0.009 capric acid (c10:0) 3.21 0.072 lauric acid (c12:0) 32.72 0.071 myristic acid (c14:0) 18.38 1.22 0-0.1 palmitic acid (c16:0) 13.13 2.4 14.1-15.3 stearic acid (c18:0) 3.6 3.7-9.8 oleic acid (c18:1) 12.88 20.15 34.3-45.8 linoleic acid (c18:2) 4.35 53.78 29-44.2 linolenic acid (c18:3) n.d 1.30 0-0.03 % unsaturation 17.23 73.93 63.3-90 duringtherecordwouldbeminimizedwithsetuptheexposure value (ev) in 1600. the result of the video recording is to be converted to image in jpeg format using "free video to jpg converter" to know the detail of the evolution of ame. the thermocouple was plugged into the dataq acquisition system to measure the droplet combustion temperature. this installation was connected to the computer to display the result in excel form. the experiments were performed in normal gravity and shown schematically in figure 1. a microliter syringe creates a droplet and takes it to suspend in the junction of the thermocouple. thus, the nickel coil heater and video recording are turned on together to ensure data take at the same time with the thermocouple. when ame-o occurs, all measurement takes a stop. figure 1. droplet combustion experimental set-up 3. result and discusssion 3.1 fuel physical properties the result of density according to figure 2; for cjo, kso, cco, namely 0.921 gr/ml, 0.917 gr/ml, 0.913 gr/ml, then add clove oil become slightlyhigh at 0.93 gr/ml, 0.926 gr/ml, 0.923 gr/ml. the previous experiments result the density of cjo, kso, cco, namely 0.901-0.940 gr/ml (no, 2011), 0.923 gr/ml (vedharaj et al., 2013), 0.920 gr/ml (chinnammaetal.,2015). thefuel injectionprocessdependsonthe densitydue to the estimation in its volume (sajjadi et al., 2016). cco has a lowerdensity than cjo and kso. molecularweight and structure are the factors that aect density. vegetable oil has a molecular weight of 600-900 g/mol (misra and murthy, 2010) due to triglycerides and their fatty acid. based on table 2, fatty acids with double bonds in each vegetable oil are cjo±80%, kso±70%, and cco±18%. it can be stated that density increases in vegetable oil with a high percentage of unsaturated fatty acid. the aromatic structure that compounds clove oil consists of one aromatic ring and a few sides of the alkyl chain. the aromatic ring that arranged in a dense and rigid was inuenced a high density of clove oil. the result shows that blending with clove oil at 5% makes all the density of vegetable oil increase. cjo95c5 is the highest density due to the unsaturated fatty acid percentage until 80%. since the density of vegetable oil and its blend higher than diesel fuel (0.840 gr/ml), the use of fuel blends in diesel fueling systems would require modication of the equipment designed to work with a lighter fuel (laza and bereczky, 2011). figure 2. the density of vegetable oil and their mixture figure3 illustrates theeectsofmixedcloveoil at5%onthe viscosity of vegetable oil. cjo and kso are a higher viscosity than cco due to the percentage of oleic acid in cjo and kso higher than in cco. oleic acid is an unsaturated fatty acid with a single double bond. the presence of a single double © 2022 the authors. page 502 of 507 gamayel et. al. science and technology indonesia, 7 (2022) 500-507 figure 3. the viscosity of vegetable oil and their mixture bond leads to increase viscosity, whereas two or three double bonds caused a decrease in viscosity (demirbas, 2008). it gave rise to stronger intermolecular interaction between the 𝜋 electron of the double bond because a spatial geometry of the cis conguration of the one double bond of oleic still allowed a close packing between a molecule (romuli et al., 2019). the stronger intermolecular interaction causes the motion of the molecule to become inactive and viscosity is become increase. in this experiment, cco is the most viscous oil due to more percentage of lauric acid, which has a weak van der waals interactions and does not have strong orbital. basedonfigure3,viscositydecreasedto10%whenblended with clove oil 5%. viscosity in 24.33 mm2/s2 reached by cco mixed with clove oil 5% marked as lower viscosity than kso and cjo. meanwhile, the viscosity of clove oil is 4.1 mm2/s (mbarawa,2010) betweentherangeofdiesel fuelviscosity(2.25.3 mm2/s). it can be stated that all of these vegetable oils and their blend can’t directly use in the engine due to the viscosity number not being in the range of diesel fuel. it requires fuel modication like preheating or transesterication to biodiesel. figure 4. the illustration motion of molecule (a) vegetable oil, (b) add clove oil vegetable oils are non-polar molecules with a low degree of electronegativity. the intermolecular bond in vegetable oils is the london dispersion force with the instantaneous dipole and the aected dipole. the london dispersion force causes the molecule to move even if only for a moment. adding clove oil makes the motion of the triglycerides becomes active. clove oil is moderately polar due to eugenol and terpene being a major compound that has a hydroxyl group (-oh) and aromatic structure. the dipole generated by eugenol that its polarity induced by the hydroxyl group (-oh). the electron has active motion around the aromatic ring which is called delocalized. the repulsive and attractive force created byelectron motion between aromatics and triglyceride. the force leads to molecule oscillation between them. a detailed illustration of the molecule’s motion can be seen in figure 4. with more oscillation of molecules on the fuel blend, viscosity would be lower or the fuel mixture more viscous. the ash point of vegetable oil depends on molecular weight, long-chainhydrocarbon, andthedegreeofdoublebond fatty acid (carareto et al., 2012; keshavarz and ghanbarzadeh, 2011). the previous paper reported that the molecular weight of vegetable oil is 20% higher than diesel fuel and causes low volatility (misra and murthy, 2010; no, 2011). vegetable oil has a strong london dispersion force caused by its large molecular weight and bulky structure. that makes vegetable oil need more energy to vaporize and dicult to ignite when exposed to a ame. figure 5. the flash point of vegetable oil and its blend figure 5 shows that the ash point of kso is the highest. other literature blin et al. (2013) was stated that the higher percentage of the single double bond composition in the vegetable oil led to a higher ash point. more energy is needed to break this interaction and release the molecule which is in the liquid to vapor phase to form a combustible mixture in air. it produces higher temperature in the liquid where the temperature is the main factoron the ash observed. the mixture at 5% clove oil on vegetable oil can depress the ash point until 30%. all vegetable oils that add 5% clove oil has the ash point in the range of 182-188◦c. it means that the blended fuel with clove oil increases the volatility and consumes lower energy than usual to obtain the same evaporation amount. the aromatic structure and hydroxyl group in clove oil are the main factor to depress the ash point in vegetable oil. the presence of aromatic structure and hydroxyl group makes molecular interaction of triglyceride weaker than usual and causes oscillation of triglyceride more active. as a result, the fuel blend needs lower energies to be vaporized into the vapor phase. at the © 2022 the authors. page 503 of 507 gamayel et. al. science and technology indonesia, 7 (2022) 500-507 ash point, the concentration of vapor on a fuel surface is equal to the lower explosive limit (lel) of the vegetable oil-clove oil, vapor-air mixture. 3.1.1 droplet combustion figure 6. the sequence of droplet combustion in vegetable oil and its blend figure 6 exhibit the ame evolution with the sequence in each frame is 0.04 second with the result that cco and cco95c5 get a more complete combustion process than kso and cjo. the ovoid ame denes as a ame with the similar shape of an egg and has around in tip ame. it explains perfect combustion in the sequence of ame. it’s exhibits that the ovoid ame occurs more frequently in cco than in kso and cjo. the ovoid ame that occurs in cco was captured in 10 frames, cco95c5 in 11 frames, kso and cjo in the range of a 6-8 frame. generally, the geometry of ame gets dierences from the rst ignition, micro-explosion, and ame extinction in cco, kso, cjo, and its blend. the bulge geometry of ame and rapid change becomes like a spike is the mark of the initial micro-explosion (wardana, 2010). in cco, the geometry of ame is like an ovoid from the start ignition until 0.4 seconds and then the bulge geometry and spike ame height take place. the ovoid ame geometry takes place in cco95c5 more than in cco. it takes time in 0.48 second before the bulge geometry and spike ame starts. the ovoid ame geometry in cco and its blend has a long duration time due to the presence of lauric acid which contain up to 30% in triglyceride that led to stable combustion. in cco, the change of oil in liquid phase to vapor phase, namely lauric acid, unsaturated fatty acid, and glycerol. lauric acid is a carbon chain without a double bond with the advantages such as creating a combustion process perfectly and being easier to evaporate than fatty acid with a double bond. in cco95c5, the fuel component that has been evaporated namely eugenol, terpene lauric acid, unsaturated fatty acid, and glycerol. figure 6 exhibits the micro-explosion in cjo, kso, and its blend occur earlier than cco. the unsaturated fatty acid contains in cjo and kso until 70% leads to viscosity higher than cco and its blend. vegetable oil with high viscosity causes eugenol and terpene trapping in the droplet. the rapid evaporation of eugenol and terpene lead to micro-explosion inside the droplet and form secondary atomization outside the droplet. the presence of eugenol, terpene, and the double bond in kso and cjo aect the geometry of ame. micro-explosion in kso and cjo take place due to the saturated and unsaturated fatty acid having dierences in volatility. figure 7. flame geometry at micro-explosion (a) cco, (b) cco95c5, (c) kso, (d) kso95c5, (e) cjo, (f) cjo95c5 figure 7 exhibit the ame geometry at micro-explosion phenomenaineachvegetableoilanditsblend. micro-explosion exhibits the ame geometry of kso95c5 and cjo95c5 have disruptive burning due to trapped molecules in droplets like eugenol and terpene. they have great volatility that creates them to come out of the droplet and initiate more microexplosion. theevaporationphasecreates thegrowthofbubbles inside the droplet. it leads to an internal pressure increase and the droplet sheet becomes thinner (rao et al., 2017). due to the pressure, the bubble comes out from the droplet and form secondary atomization, resulting in a substantial decrease in droplet size and an increase in burning rates (coughlin and hoxie, 2017). the small size of the bubble that ejected outside thedropletwaseasier toburnthanthemaindropletandformed a spherical ame. at that moment occur the ame-in-ame phenomena, which was illustrated in figure 8. figure 8. the sequence of coming out bubbles creates micro-explosion and flame-in-flame the thermocouple signal is given from the droplet that was ignited on the k-type thermocouple shown in figures 9 and 10. heating, evaporation, and burning are the step of the droplet combustion process. when the coil heater ignited, heat transfer takes place from coil to droplet until reached around 400◦c to 500◦c. at this temperature, evaporation and droplet © 2022 the authors. page 504 of 507 gamayel et. al. science and technology indonesia, 7 (2022) 500-507 figure 9. the droplet combustion result of vegetable oil ignition occurs at the same time. the dierences in volatility at each compound led to evaporation occurring in more than one step. the burning process is identied as increasing steeper temperature from ignition temperature until peak temperature, then continuing to burn out temperature. based on figure 9, cco has a lower ignition delay than cjo and kso due to their chemical composition such as lauric acid in apercentage of 47%. ccoisalsocalledsaturatedoilbecauseof thepresenceof lauric acid and stearic acid. more sequential ch2 (methylene) groups in the fatty compound cause the ignition delay to become short and the cetane number becomes high. on the opposite, long ignition delay times with low cetane numbers and subsequent poorer combustion have been associated with more highly unsaturated components. the peak temperature in figure 10 shows that kso and cjo are higher than cco. the presence of a double bond in their composition caused more energy to abstract hydrogen bonds until complete combustion. more energy is identied as more combustion temperature in the droplet. kso and cjo are bulkier than cco because they have rigid molecules. this rigid molecule led to evaporation and burning diculties at low temperature. cjo has the highest peak temperatures due to its density of cjo is the highest. besides that, cjo has unsaturated fatty acid composition more than cco. in the range of temperature 400-500◦c, evaporation and droplet ignition occurat the same time. figure 11 describes the presence of clove oil that aects droplet ignition temperature. the ignition delay time of dierent fuels varied greatly, which was mainly related to the ash point of the fuel (meng et al., 2020). the volatility of clove oil created evaporation time to become concise and ignition occurred at a lower temperature. the previous study mixed the coconut oil with clove oil in 10% basis volume and have the lowest ignition temperature if compare with the present study. it means that more percentage of clove oil in the fuel blend can decrease the ignition temperature and get a lower ignition delay time. figure 10. the droplet combustion result of vegetable oil blended with clove oil 5% figure 11. the ignition temperature of vegetable oil and its blend 4. conclusion the density of vegetable oil mixed with clove oil is slightly higherthanpurevegetableoil. cjo,kso,cco,namely0.921 gr/ml, 0.917 gr/ml, 0.913 gr/ml, then add clove oils become slightly high at 0.93 gr/ml, 0.926 gr/ml, 0.923 gr/ml. it’s due to the cumulative large molecular weight and the bulk structure of vegetable oil with the dense and rigid molecules of clove oil. as the density of the fuel blend is higher, fuel consumption will increase. the viscosity of vegetable oil mixed with clove oil is lower than pure vegetable oil. viscosity cjo, kso, and cco namely decrease from 37.17 to 33 mm2/s, 37.83 to 35.24 mm2/s, 30.1 to 24.43 mm2/s. the energy input in the molecule creates rotation and vibration movement that causes the viscosity to decrease. the ash point of vegetable oil mixed with clove oil lower than pure vegetable oil. their mixture can decrease the ash point to 35%. it’s due to the volatility of clove oil creating short evaporation time in the fuel blend. droplet combustion of vegetable oil blended with clove oil gets a shorter ignition delay time than pure vegetable oil. the presence of clove oil can reduce the ignition delay time by 5%. it’s due to the volatility of clove oil that can reduce the evaporation time and trigger the ignition. in vegetable oil © 2022 the authors. 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(2010). combustion characteristics of jatropha oil droplet at various oil temperatures. fuel, 89(3); 659– 664 wirawan, i., i. wardana, r. soenoko, and s. wahyudi (2014). premixed combustion of kapok (ceiba pentandra) seed oil on perforated burner. international journal of renewable energy development, 3(2); 91–97 © 2022 the authors. page 507 of 507 introduction experimental section materials methods fuel physical properties droplet combustion result and discusssion fuel physical properties droplet combustion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper waste collection vehicle routing problem with time windows for route optimization of garbage transport vehicles evi yuliza1*, bambang suprihatin1, putra bahtera jaya bangun1, fitri maya puspita1, indrawati1, sisca octarina1 1department of mathematics, universitas sriwijaya, ogan ilir, 30662, indonesia *corresponding author: eviyuliza@mipa.unsri.ac.id abstractthe waste collection vehicle routing problem with time windows is an optimization problem on the route of the waste transportvehicle which aims to determine the route of the vehicle by considering the travel time and windows. garbage transport vehiclestransport garbage in several work areas. this affects the optimal time and distance. the working hours of the garbage collectors aredivided into two parts. the first working hours are 07.00 11.00 west indonesian time (wit) and 16.00-20.00 wit. the cleaningstaff has a break of 5 hours. this study aims to optimize the route of waste transportation vehicles in the problem of transportingwaste so as to minimize travel time and distance. waste collection vehicle routing problem with time windows on determining theroute of a garbage transport vehicle which is simulated on the problem of transporting garbage in the city of palembang. the wastecollection vehicle routing problem with the time windows model is solved with an exact approach using lingo software. the resultsof this study indicate that the proposed optimization model provides optimization of the route of the garbage transport vehicle, thetotal travel time, and break time of the cleaning staff. keywordswaste, transportation, vehicle routing problem, travel time, break time received: 9 october 2022, accepted: 23 december 2022 https://doi.org/10.26554/sti.2023.8.1.66-70 1. introduction the problem of vehicle routes in optimization can be discussed in the vehicle routing problem (vrp). dantzig ramser introduced the truck dispatching problem in 1959 which minimized the distance traveled from trucks with homogeneous characteristics so that they could serve oil demand from a number of gas stations (ibrahim et al., 2019; izar et al., 2016; jepsen and pisinger, 2011; mamat et al., 2016). furthermore, clarke and wright in 1964 generalized this problem in the field of logistics and transportation, hereinafter known as the vrp (braekers et al., 2016; lahyani et al., 2015). vrp problems have been widely researched and developed in various fields, such as logistics, transportation, economics, and communications (gounaris et al., 2013) . classical vrp aims to determine vehicle routes starting from the depot, ending at the depot for vehicles with the same capacity so that each customer is visited once and each vehicle only has one route (atefi et al., 2018; borcinova, 2017; izar et al., 2016; nazari et al., 2018). vrp has been widely studied related to optimization problems that aim to identify efficient and optimal vehicle routes for distance or travel costs (assaf and saleh, 2017; azad and hasin, 2019; munari et al., 2019). vrp can be related to the problem of garbage collection routes (wahyukaton and rochaeni, 2019; yuliza et al., 2020; yuliza et al., 2021). service for each customer must be started in corresponding time intervals called time windows. the time window can be interpreted as the time interval between departure time and arrival time (desaulniers et al., 2014; el-sherbeny, 2010). the problem of waste collection is a problem faced by an area, especially urban areas lu et al., 2015. in this paper, we study a variant of the vehicle routing problem (vrp) as a waste collection vehicle routing problem with time windows. rossit et al. (2021) proposed a simulated annealing algorithm to overcome the route of garbage collection vehicles based on mixed integer programming and metaheuristic methods, large neighborhood search, and genetic algorithms. the waste collection vehicle route problem is modeled with a scheduling strategy and an environmentally friendly solution is sought (korcyl et al., 2019; lu et al., 2015). zhou et al. (2022) proposed a model to optimize the solid waste collection and transport routes that have become an issue in china. markovic et al. (2019) solve the problem of transporting waste in urban areas with a metaheuristic approach based on the waste collection vehicle routing problem on stochastic demand and travel time. https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.66-70&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.66-70 yuliza et. al. science and technology indonesia, 8 (2023) 66-70 perea et al. (2016) analyzed the problem of transporting waste by considering different types of waste based on heuristics. bee algorithm was applied to overcome capacitated vehicle routing problem (cvrp) issues which aim to provide a suggested solution regarding the waste hauling route for the upcoming itf sunter project. based on the cvrp, the capacity of the waste transported will not exceed the capacity of the waste transport vehicles (natalia et al., 2021) . this study will discuss the optimization model of the waste collection vehicle routing problem with time windows on the waste transportation route in the city of palembang by considering the rest time parameter. this study aims to optimize the route of waste transportation in the city of palembang against time windows. more specifically, looking for the optimal route that minimizes the total distance traveled by waste transport vehicles. the problem from this research will be modeled as a waste collection vehicle routing problem with time windows. the mixed integer programming formulation of the waste collection vehicle routing problem with time windows was solved using the branch and bound method using lingo software (hartono et al., 2018; puspita et al., 2018; yuliza et al., 2020). the model will be implemented on the problem of waste transportation routes in the ilir barat i district i, palembang city. an efficient procedure is designed to solve the waste collection route problem in the waste collection vehicle routing problem model so as to minimize the distance and travel time. the city of palembang has a department of environment and hygiene (deh) which oversees and is responsible for the environment and cleanliness in the city of palembang. each deh officer is responsible for one work area. the officers are assigned to one particular area and serve several temporary disposal sites (tds) to final disposal sites (fds) by using waste transport vehicles such as containers, dump trucks, or arm rolls. the process of transporting waste is divided into two periods. the first working hours are from 07.00-11.00 west indonesian time (wit) and 16.00-20.00 wit. there are a break 5 hours for the officers. this study will also discuss the break time of the officers. the free 5 hours between the working hours of the first session and the second session can be used by officers to rest. garbage transport vehicles will pick up waste from several tds and take it to the fds. garbage transport routes are carried out randomly so that the time and distance traveled are not optimal. 2. experimental section 2.1 materials data on waste transportation routes were obtained from deh. the problem of transporting waste can be viewed as a weighted directed graph. the set of all tds and fds can be expressed as nodes and the journey from tds i to tds j can be expressed as arc, written g= (v,a) where g= 1,2,· · · ,n and v=(i,j)|i= 1,2,· · · ,n, and j= 1,2,· · · ,n. some assumptions in this study are as follows: vehicle capacity some assumptions the average speed of garbage transporting vehicles is 40 km/hour, traffic jams are ignored, traffic lights are ignored, engine damage is neglected, the distance from tds i to tds j is considered the same or the matrix is symmetrical, service time about 5 minutes and the capacity of the garbage vehicle is assumed to be 8 tons. 2.2 methods the waste collection vehicle routing problem with the time windows model is formulated which is implemented on the waste transportation route problem. this model is solved by the branch and bound method with the help of lingo software. the procedure of this research is shown in figure 1. figure 1. illustration of research flow 3. result and discussion the mathematical model of the waste collection vehicle routing problem with time windows is formulated as follows: min z = ∑︁ (i, j)𝜖a di jxi j (1)∑︁ j𝜖v xi j = 1, for i𝜖v (2)∑︁ j𝜖v xji = 1, for i𝜖v (3) qi ≤ yi ≤ q, for i𝜖v (4) yi − yj + qj ≤ q(1 − xi j), for (i,j) 𝜖a (5) © 2023 the authors. page 67 of 70 yuliza et. al. science and technology indonesia, 8 (2023) 66-70 ∑︁ ( j,i)𝜖a, j≠i xji − ∑︁ (i, j)𝜖a,i≠j xi j =  −1, for = 0 1, for = d 0, the others (6) ai ≤ ti ≤ bi , for i𝜖v (7) ti − tj + (bi + ti j − aj)xi j ≤ bi − aj , for (i,j) 𝜖a (8)∑︁ ( j,i)𝜖a yi j = 1, for i𝜖v (9) yi j ≤ ii j , for (i,j) 𝜖a (10) xi j𝜖 {0, 1}, for (i,j) 𝜖a (11) yi j𝜖 {0, 1}, for (i,j) 𝜖a (12) the journey from tds i to tds j is denoted by xi j. the generation transported at the tds to i and the generated transported at the tds to j are denoted by yi and yj. departure time from tds to i and travel time from tds to j are denoted by ti and tj. the officer’s rest time from tds i to tds j is denoted by yi j. the distance from tds i to tds j is denoted by di j.the departure time of vehicles when transporting waste at tds to i is denoted by ai.the arrival time of vehicles when transporting waste to tds j is denoted by bj. garbage load at tds to i is denoted by qi. vehicle capacity is denoted by q.the travel time from tds i to tds j is denoted by ti j. the definitions of each variable and parameter are given in table 1. table 1. variable and parameter for the waste collection vehicle routing problem with time windows variable parameter xi j di j yi ai yj bj ti qi ti ti j yi j q the waste collection vehicle routing problem with the time window model is implemented on the problem of waste transportation routes in ilir barat i district, palembang city. the solution of the waste collection vehicle routing problem with time window model is solved by lingo software. the solver of lingo is the branch and bound method. the calculation results are as in table 3. the calculation results of the waste collection vehicle routing problem with the time window model produce a minimum total distance of 264.05 km and a total travel time of 6.6 hours (assumption that the average speed of garbage transporting vehicles is 40 km/hour). in the first session, the working hours of officers are 4 hours and in the second session, the working hours of officers are 2.6 hours. the total working hours of the first session and the second session are 8 hours so the officer has a waiting time of 84 minutes. this shows that the waste table 2. data on transportation type and amount of tds in ilir barat i district district vehicle code transportation type amount of tds district 1 20 container 1 district 2 27 dump truck 7 district 3 28 container 2 district 4 29 dump truck 5 district 5 30 dump truck 6 district 6 31 amroll 4 district 7 32 dump truck 7 district 8 33 dump truck 3 district 9 34 dump truck 7 table 3. solution of the waste collection vehicle routing problem model with time window vehicle code minimize distance (km) transport route 20 0.95 a1-a2 27 21.01 a1-t-b6-b5-b7-b2-b3-b4-t 28 31.4 a1-t-c2-c1 29 26.57 a1-t-d4-d2-d5-d3-t 30 40 a1-t-e6-e2-e4-e3-e5-t 31 34.5 a1-t-f3-f2-t 32 19.68 a1-g3-g2-g5-g4-t-g7-g6-t 33 43.8 a1-t-h3-h2-t 34 46.14 a1-i6-i4-t-i2-i5-i3-t where node a1: 1st tds and node t: fds, the others: another tds collection vehicle route using the waste collection vehicle routing problem with the time window model produces an optimal total distance and travel time. 4. conclusion the waste collection vehicle routing problem with the time window model can be implemented on the waste transportation route problem. this model observed to time windows and officer rest periods. solution of the waste collection vehicle routing problem with time window model obtained optimal mileage and travel time. 5. acknowledgment the research of this article was funded by dipa of public service agency of universitas sriwijaya 2022. sp dipa023.17.2.677515/2022 on december 13, 2021. in accordance with the rector’s decree number : 0109/un9.3.1/sk/ 2022, on april 28, 2022. © 2023 the authors. page 68 of 70 yuliza et. al. science and technology indonesia, 8 (2023) 66-70 references assaf, r. and y. saleh (2017). vehicle-routing optimization for municipal solid waste 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11498 © 2023 the authors. page 70 of 70 introduction experimental section materials methods result and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper the risk cluster in type 2 diabetes mellitus based on risk parameters using fuzzy c-means algorithm marhamah1, sugiyarto surono2*, endang darmawan1 1department of pharmacology and clinical pharmacy, faculty of pharmacy, ahmad dahlan university, yogyakarta, 55164, indonesia2department of mathematics, faculty of applied science and technology, ahmad dahlan university, yogyakarta, 55191, indonesia *corresponding author: sugiyarto@math.uad.ac.id abstractthe prevalence of type 2 diabetes mellitus increases every year. in the long term, type 2 diabetes mellitus can lead to complicationsof other diseases. this study aimed to analyze the risk cluster for type 2 diabetes mellitus based on risk parameters using the fuzzyc-means algorithm. the benefit of analyzing the risk cluster as an initial screening to prevent the occurrence of type 2 diabetesmellitus. this study used 905 subjects’ data consisting of 562 males and 343 females. after the data preprocessing, the optimalnumber of clusters was determined using a fuzzy c-means algorithm process. subsequently, the pearson correlation test wasconducted to determine the correlation between the risk parameters of type 2 diabetes mellitus and the cluster results. the studyresulted in 2 risk clusters, subjects in cluster 1 were older than 60 years (34.1%), had a family history of type 2 diabetes mellitus(62.7%), had hypertension (55.4%), routinely took medicines (73.5%), undertook physical activity for less than half an hour (40.5%),and had a high blood pressure level (53.5%). the pearson correlation test found that age, regular medication use, hypertension andblood pressure level all seem to have significant correlations with cluster outcomes. the risk cluster of type 2 diabetes mellitus wasseparated into two clusters using fuzzy c-means algorithm, namely the high-risk cluster and the low-risk cluster. keywordstype 2 diabetes mellitus, cluster analysis, fuzzy c-means algorithm, pearson correlation received: 10 august 2022, accepted: 10 november 2022 https://doi.org/10.26554/sti.2023.8.1.17-24 1. introduction diabetes mellitus is a chronic condition that occurs due to increase blood glucose levels, resulting from insucient production of insulin hormones or insulin that does not work optimally due to damage to pancreatic beta cells (sarría-santamera et al., 2020). the risk factors are lack of physical activity, family history of diabetes mellitus, certain racial/ethnic groups, gestational diabetes history, hypertension history, high density lipoprotein (hdl) 150 mg/dl, smoking, prediabetes history, cardiovascular disease history, and age >45 years without the previously mentioned risk factors (association, 2021). the symptoms include polyuria, polyphagia, polydipsia, and unexplained weight loss (virani et al., 2021). type 2 diabetes mellitus has been identied as the world’s leading cause of mortality (pham et al., 2020). in 2019, the international diabetes federation estimated that 463 million adults aged 20-79 years had diabetes, and this number was predicted to reach 578.4 million and 700.2 million in 2030 and 2045 worldwide, respectively (saeedi et al., 2019). type 2 diabetes mellitus could cause complications such as heart attack, stroke, neuropathy, nephropathy, retinopathy, and kidney failure (mezil, 2021). early screening for the risk of type 2 diabetes mellitus should be conducted to prevent the disease. previous studies had predicted the risk of type 2 diabetes mellitus using classication techniques (logistic regression, k-nearest neighbor, support vector machine, decision tree classication, and random forest classication) (tigga and garg, 2020). this study used a dierent approach-cluster analysis-to identify the type 2 diabetes mellitus risk group. the ability of cluster analysis to categorize substantial amounts of data and a variety of variables was one of its benets (muslimatin, 2011). cluster analysis divides similar objects into a group and diers from others based on distance measures (madhulatha, 2012). one of the methods in cluster analysis was the fuzzy c-means algorithm, a clustering method in which the level of data presented was determined by the degree of membership introduced, the membership value allows it to be between 0 and 1 (ramya, 2018). fuzzy c-means clustering have been used to predict the level of diabetes mellitus, so that it can assist medical perhttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.17-24&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.17-24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 figure 1. flow chart of methods sonnel in determining the right treatment therapy for patients (jamuna, 2020). kunwar et al. (2019) used fuzzy c-means method to assist clinical decision-making regarding kidney failure which showed there were 7 clusters. the existence of this grouping is an eort to prevent early kidney failure so that timely treatment can be given and reduce the risk of death. subsequently, sanakal and jayakumari (2014) performed a diabetes mellitus prognosis by comparing fuzzy c-means algorithm with support vector machine (svm), showing the fuzzy c-means algorithm accuracy of 94.3%, but was 59.5% for svm. lomo et al. (2021) used fuzzy c-means clustering to identify patients with type 2 diabetes mellitus, based on demographic factors, blood glucose levels, the patient’s surviving condition, and medication. it revealed that there were three clusters, each representing a patient’s condition that helped individuals with type 2 diabetes mellitus live longer. therefore, this study aimed to perform a risk cluster analysis of type 2 diabetes mellitus by identifying the characteristics of the risk parameters using the fuzzy c-means algorithm. compared to earlier studies, more and dierent variables were used in this cluster analysis study to assess the risk of type 2 diabetes mellitus. some variables were used to test the risk of type 2 diabetes mellitus, as used by the association (2021). 2. experimental section 2.1 materials this study used secondary data obtained from kaggle datasets of diabetes owned by tigga with 952 subjects aged >18 years old, female and male (tigga and garg, 2020). they were asked to answer a questionnaire containing questions about theirhealth, lifestyle, andfamilybackground, as shownintable 1 (tigga and garg, 2020). after the blank data were removed, 905 subjects were obtained, consisting of 562 males and 343 females. 2.2 methods the data were analyzed using the python program with the followed stages (see figure 1) : 1. read data the data is read used pandas library in python. 2. data preprocessing a. data conversion from categorical to numerical data in the categorical form should rst be converted into numerical form. the categorical data contained in the parameters of age, gender, family history of diabetes, hypertension, physical activity, smoking, alcohol configure 2. flow chart of research subject selection sumption, regularly taking medication, consumption of fast food, stress, blood pressure level, gestational diabetes history, and frequency of urination. b. blank data elimination blank data were excluded from this study, yielding 905 nal results (see figure 2). c. data normalization datanormalizationwasconductedusingz-score tomake each parameterhad adistribution in the same range. the data normalization formula is as follows (gökhan et al., 2019): z = (x − `) 𝜎 (1) where: x = observed value ` = average 𝜎 = standard deviation z = z-score (raw value) d. the determination of the optimal number of clusters the elbow method was used to analyze and determine theoptimaldataset cluster. itbeganbyplotting thevalues resulting from the function of the number of clusters and marking them at the elbow of the curve. subsequently, the curve provided information about the number of clusters used. for example, when the value of the rst and second gave the angle on the graph or the value that had decreased the most, the number can be used (kurniawan et al., 2020). 3. data clustering using the fuzzy c-means algorithm. 4. analyzing the results of clusters to determine the characteristics or distribution of each parameter from each obtained cluster. 5. doing a correlation test on the cluster results to measure thecorrelationbetweentheparametersused inthecluster and the cluster results. the interpretation of pearson correlation coecient is shown in table 2 (hinkle et al., 2003). © 2023 the authors. page 18 of 24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 table 1. risk parameters of type 2 diabetes mellitus of the subjects (tigga and garg, 2020) parameters category age < 40 years 40-49 years 50-59 years >60 years gender male female family history yes/no hypertension yes/no physical activity none less than half an hour more than half an hour one hour or more smoking yes/no alcohol consumption yes/no routinely taking drugs yes/no fast food consumption occasionally often very often always stress not at all sometimes very often always blood pressure level low/normal/high gestational diabetes history yes/no urination frequency not much/quite often body mass index (bmi) numeric (15-45 kg/m2) sleep time numeric (4-11 hours) deep sleep numeric (0-11 hours) pregnancies numeric (0-4) table 2. the interpretation of pearson correlation coecient (hinkle et al., 2003) size of correlation interpretation .90 to 1.00 (-.90 to -1.00) very high positive (negative) correlation .70 to .90 (-.70 to -.90) high positive (negative) correlation .50 to .70 (-.50 to -.70) moderate positive (negative) correlation .30 to .50 (-.30 to -.50) low positive (negative) correlation .00 to .30 (.00 to -.30) negligible correlation © 2023 the authors. page 19 of 24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 figure 3. the results of the cluster of subjects at risk of type 2 diabetes mellitus using the fuzzy cmeans algorithm (cluster 1 is depicted in blue and cluster 2 is depicted in red) 3. result and discussion 3.1 strand geometry the risk parameters of the subject in this study are described in table 1. figure 3 shows the data distribution plot of risk cluster results, cluster 1 is depicted in blue and cluster 2 is depicted in red. the optimal number of risk clusters of type 2 diabetes mellitus obtained was 2 clusters. cluster 1 consisted of 370 subjects, while cluster 2 consisted of 535 subjects. the risk cluster results using the fuzzy c-means method can be seen in table 3 and table 4. cluster 1 was dominated by subjects with 34.1% aged > 60 years, with a family history of type 2 diabetes mellitus (62.7%), who have hypertension (55.4%), who regularly take drugs (73.5%), who did physical activity for less than half an hour (40.5%), and who have a high blood pressure level (53.5%). in addition, cluster 1 predominantly consisted of subjects with an average body mass index (bmi) of 27.84 kg/m2 and the average sleep time was 6.75 hours. cluster 2 was dominated by subjects under the age of 40 (77.0%), who did not have a family history of type 2 diabetes mellitus (62.4%), had no history of hypertension (97.2%), did not frequently take medicines (90.5%), did more than half an hour of physical activity (31.0%), and had a normal blood pressure level category (92.7%). furthermore, the average sleep time was 7.09 hours and the bmi was 23.9 kg/m2. the pearson correlation test showed the highest correlation value with the clusterresults on the age parameter (-0.67), regularly taking medication (-0.66), hypertension (-0.60), and blood pressure level (-0.59). ourstudyshowed that cluster1 had asignicant probability of acquiring diabetes mellitus, because many of the subjects in this cluster had diabetes mellitus risk parameters. the risk parameters were being aged >60 years, having a family history of diabetes, having hypertension, taking medication regularly, doing physical activity for less than half an hour, having high blood pressure levels, having an average bmi of 27.84 kg/m2, and sleeping less than 6.75 hours. in this study, subjects aged more than 60 years old were in the cluster with a high-risk of developing diabetes mellitus based on fuzzy c-means clustering. these results are consistent with previous studies which reported that the prevalence of diabetes mellitus increased at 5564 years of age and decreased after passing this range. therefore, aged people were at high risk of developing diabetes mellitus (association, 2021). asiimwe et al. (2020) showed that the age group of 61–65 years was strongly inuenced by diabetes mellitus. the metaanalysis results also showed an increase in the likelihood of diabetes mellitus at age 40 years compared with those aged <40 years (asamoah-boaheng et al., 2019). aging can increase the occurrence of chronic inammation. in addition, there is an increase in the concentration of free fatty acids in the blood due to impaired lipid metabolism in the elderly. this can lead to insulin resistance (ismail et al., 2021). in several studies, a family history of diabetes mellitus has beenlinkedtoanincreasedriskofdevelopingtype2diabetes. a cross sectional study conducted by zhang et al. (2015) showed that there was a signicant increase in the prevalence of diabetes mellitus in study participants who had two generations of rst-degree relatives with diabetes with a history of diabetes by 32.7%, then only one generation of rst-degree relatives with a history of diabetes by 20.1% and no rst-degree relatives with diabetes at 8.4%. the rst-degree relatives of diabetes mainly had 𝛽-cell dysfunction, and that the higher the family history risk category, the more severe the 𝛽-cell dysfunction. gopalakrishnan and geetha (2017) reported that almost 68.8% of patients with diabetes mellitus had a family history of diabetes in which mothers with diabetes had a greater inuence than fathers with diabetes. the meta-analysis conducted by asamoah-boaheng et al. (2019) showed that a family history of diabetes mellitus had a signicant relationship with the occurrence of diabetes mellitus in a person. based on hypertension parameters, cluster 1 was dominated by subjects with a history of hypertension. study showed that the prevalence of hypertension in patients with type 2 diabetes mellitus is 59.5% higher in the 50-60-years age group (akalu and belsti, 2020). wei et al. (2011) reported a signicant relationship between the incidence of type 2 diabetes mellitus and hypertension compared to normal blood pressure in white. the study by kim et al. (2015) showed that diabetes mellitus was higher in initial subjects with pre-hypertension and hypertension than those with normal blood pressure and subjects who had normal blood pressure at the beginning of the examination later. after eight years, prehypertension or hypertension was at a signicantly higher risk of developing diabetes mellitus in subjects compared to those with controlled blood pressure. wangetal. (2018) reportedthatmoderate levelsofphysical activity (30 minutes/3 days) had a signicant relationship with the occurrence of type 2 diabetes mellitus. the study by sim© 2023 the authors. page 20 of 24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 table 3. the results of the cluster of subjects at risk of type 2 diabetes mellitus using the fuzzy cmeans algorithm based on categorical parameters parameters cluster results pearson correlation (r)cluster 1 cluster 2 total n = 370 % n = 535 % n = 952 age <40 years 50 13.5 412 77.0 462 -0.67 40-49 years 70 18.9 83 15.5 153 50-59 years 124 33.5 24 4.5 148 >60 years 126 34.1 16 3.0 142 gender male 207 55.9 355 66.4 562 0.11 female 163 44.1 180 33.6 343 family history yes 232 62.7 201 37.6 433 0.25 no 138 37 334 62.4 472 hypertension yes 205 55.4 15 2.8 220 -0.60 no 165 44.6 520 97.2 685 physical activity none 67 18.1 62 11.6 129 0.15 less than half an hour 150 40.5 167 31.2 317 more than half an hour 85 23.0 166 31.0 251 one hour or more 65 18.4 140 26.2 208 smoking yes 40 10.8 66 12.3 106 0.023 no 330 89.2 469 87.7 799 alcohol consumption yes 99 26.8 88 16.4 187 -0.13 no 271 73.2 447 83.6 718 routinely taking drugs yes 272 73.5 51 9.5 323 -0.66 no 98 26.5 484 90.5 582 fast food consumption occasionally 290 78.4 343 64.1 633 0.1 often 44 11.9 132 24.7 176 very often 20 5.4 32 6.0 52 always 16 4.3 28 5.2 44 stress not at all 39 10.5 92 17.2 131 -0.34 sometimes 168 45.4 362 67.7 530 very often 20 23.0 73 13.6 158 always 78 21.1 8 1.5 86 blood pressure level low 0 0 27 5.0 27 -0.59 normal 172 46.5 496 92.7 668 high 198 53.5 12 2.2 210 gestational diabetes history yes 10 2.7 4 0.7 14 -0.078 no 360 97.3 531 99.3 891 urination frequency not much 208 56.2 434 81.1 642 -0.27 quite often 162 43.8 101 18.9 263 © 2023 the authors. page 21 of 24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 table 4. the results of the cluster of subjects at risk of type 2 diabetes mellitus using the fuzzy cmeans algorithm based on numeric parameters parameters cluster 1 (n=370) (mean) cluster 2 (n=535) (mean) total subject (n=905) pearson correlation (r) bmi (kg/m2) 27.8 23.9 905 -0.37 sleep time (hours) 6.75 7.09 905 0.13 deep sleep (hours) 5.05 5.88 905 0.22 pregnancies 0.60 0.23 905 -0.19 bolon et al. (2020) showed that individuals with less physical activity were more likely to suer from type 2 diabetes mellitus than very active individuals. suppose a person’s physical activity was lacking; an imbalance in the amount of energy in the body occurred since the energy consumed was greater than the amount expended. the energy that entered the body and went unused was stored mainly as adipose tissue, triggering insulin resistance, causing type 2 diabetes mellitus. furthermore, lack of physical activity coupled with the consumption of carbohydrates, proteins, and fats were obesity factors that resulted in an increase in free fatty acids. therefore, it reduced the translocation of glucose transporters to the membrane plasma and causes insulin resistance. so, subjects with less physical activity were more at high-risk of developing type 2 diabetes mellitus. in this study, subjects taking medicine regularly were categorized as having a higher risk of developing diabetes mellitus. diabetes mellitus was sometimes associated with comsumption some drugs. some drugs could increase the occurrence of type 2 diabetes mellitus associated with reduced insulin production, reduced insulin sensitivity, or the occurrence of both conditions. one example of a drug-associated with the risk of diabetes mellitus was glucocorticoids, with a mechanism that could reduce insulin production and sensitivity (repaske, 2016). based on the results of a study involving subjects with autoimmune diseases, the overall risk of developing diabetes afterone yearwas 0.9% when glucocorticoids were not received. in contrast, the risk increased to 2.1% for prednisolone <5 mg (daily dose) when glucocorticoids were administered and 5.0% for prednisone 25 mg (daily dose) (wu et al., 2020). furthermore, the thiazide drug class could also increase the risk by reducing insulin production (repaske, 2016). there was an increase in fasting blood glucose in hypertensive patients given thiazide diuretics compared to those that did not receive thiazide diuretics. however, with low doses of thiazide diuretics (25 mg/day) given thiazide diuretics (hydrochlorothiazide or chlorthalidone), there were smaller changes in fasting blood glucose compared with higher doses in hypertensive patients zhang and zhao (2016) another study showed that taking antibiotics within 90 days had a higher risk of developing diabetes mellitus than those who did not use them. the use of ve or more classes of antibiotics was also at higher risk than those using only one class of antibiotics (park et al., 2021). patients are expected to discontinue the medication when diabetes mellitus is associated with the consumption of drugs (repaske, 2016). the subjects with a high blood pressure level in this study were included in the high-risk of diabetes mellitus. the results of a prospective study showed that the systolic blood pressure level in the standard, prehypertension, mild hypertension and moderate/severe hypertension groups had a risk of 19%, 30%, 31%, and 49% of having diabetes mellitus during the follow-up period without being inuenced by risk factors such as bmi and others (stahl et al., 2012). the higher average bmi indicates having a higher risk of developing diabetes mellitus. pinidiyapathirage et al. (2013) reported that a high bmi is associated with an increase in fasting plasma glucose levels. the study by liyanage (2018) showed a signicant relationship between bmi and diabetes mellitus. the majority (51%) of study participants who were overweight experienced diabetes mellitus, followed by 29.40% of normal weight and 7.80% of underweight. according to tang et al. (2021) the risk ratio for diabetes mellitus was 2.13 times for bmi 22.5<25.0 kg/m2, 2.14 times for bmi 25.0<27.5 kg/m2, 3.17 times for bmi 27.5<30.0 kg/m2, and 3.14 times for bmi ≥30,0 kg/m2. cluster 1 has a higher risk of developing type 2 diabetes mellitus on sleep time and deep sleep parameters. the metaanalysis results showed that the risk of type 2 diabetes was low at 7-8 hours of sleep per day. sleep durations shorter and longer than usual were associated with a signicantly increased risk of type 2 diabetes mellitus. a decrease in one hour was associated with 9%, and an increase of one hour was associated with a 14% increase in the risk of type 2 diabetes mellitus (shan et al., 2015). furthermore, lack of sleep also aect leptin and ghrelin hormones. the hormone leptin helps provide a feeling of fullness, while ghrelin helps increase appetite. insucient sleepdurationdecreases leptinhormoneand increases ghrelin. furthermore, lack of sleep can reduce peptide tyrosine-tyrosine and glucagon like peptide-1 hormones that help suppress hunger; hence, these changes increase appetite, cause obesity, and interfere with blood glucose control (sakamoto et al., 2018). we found that the diabetes mellitus risk parameters correlated with the obtained risk cluster were age, regularly taking medication, hypertension, and blood pressure. the obtained pearson correlation coecients between the risk parameters and the risk clusters are categorized as moderate correlation (hinkle et al., 2003). © 2023 the authors. page 22 of 24 marhamah et. al. science and technology indonesia, 8 (2023) 17-24 according to steyn et al. (2004) the risk parameters of type 2 diabetes mellitus are divided into 2, namely modiable and non-modiable risk parameters. we can start prevention as earlyas possible to reduce the modiable risk parameters of the occurrence or development of type 2 diabetes mellitus, such as changing lifestyle (uusitupa et al., 2019). these eorts include regular physical activity such as brisk walking for 30 minutes, which when done ve times a week will help increase insulin sensitivity in the body (association, 2021; steyn et al., 2004). thenmaintainanidealbodyweightbymanagingmealportions and eating foods that have balanced nutrition, namely fruits, vegetables, and whole grains that can make you full longer, accompanied by physical activity, because obesity can increase the risk of type 2 diabetes mellitus (uusitupa et al., 2019). another eort is to lead a healthy lifestyle by not smoking and not consuming alcohol because both will reduce insulin sensitivity. too little or too much sleep is also not good because it can increase the risk of type 2 diabetes mellitus, so sucient sleep duration is needed, which is 7-8 hours per day and is also benecial in improving concentration, memory, and mood. in addition, as an eort to prevent and detect the risk of diabetes mellitus, it can also be done bycontrolling blood glucose, blood pressure, and lipid prole at the nearest health care facility (association, 2021). this study had some limitations. first, the data used was secondary data obtained from kaggle. as a result, some subjects’ data were incomplete, and they were eventually dropped from the study. second, we could not conrm more detailed information from the subject, for example, the risk parameter, which stated that the subject regularly consumes drugs. we did not know the type and amount of drugs consumed by the subjects. 4. conclusion the fuzzy c-means clustering algorithm was used to cluster the results of 905 subjects, yielding clusters 1 (high risk cluster) and 2 (low risk cluster). cluster 1 was more likely to acquire diabetesmellitusdueto thepresenceofmoreprevalentdiabetes risk parameters. subjects who have risk parameters that are included in the high-risk cluster need to be aware and alert to prevent the occurrence of type 2 diabetes mellitus. further research is needed to determine whether changing the risk parameters of type 2 diabetes mellitus through lifestyle changes can reduce the risk of developing type 2 diabetes mellitus. 5. acknowledgment the authors are grateful to the faculty of pharmacy and computational math lab department of mathematics fast uad for their support. references akalu, y. and y. belsti (2020). hypertension and its associated factors among type 2 diabetes mellitus patients at debre tabor general hospital, northwest ethiopia. diabetes, metabolic syndrome and obesity: targets and therapy, 13; 1621 asamoah-boaheng, m., o. sarfo-kantanka, a. b. tuour, b. eghan, and j. c. mbanya (2019). prevalence and risk factors for diabetes mellitus among adults in ghana: a systematic review and meta-analysis. international health, 11(2); 83–92 asiimwe, d., g. o. mauti, and r. kiconco (2020). prevalence and riskfactors associated with type 2 diabetes in elderly patients aged 45-80 years at kanungu district. journal of diabetes research, 2020; 1–5 association, a. d. 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873–879 wu, j., s. l. mackie, and m. pujades-rodriguez (2020). glucocorticoid dose dependent risk of type 2 diabetes in six immune-mediated inammatory diseases: a populationbased cohort analysis. bmj open diabetes research and care, 8(1); 001220 zhang, j., z. yang, j. xiao, x. xing, j. lu, j. weng, w. jia, l. ji, z. shan, and j. liu (2015). association between family history risk categories and prevalence of diabetes in chinese population. plos one, 10(2); e0117044 zhang, x. and q. zhao (2016). association of thiazide-type diuretics with glycemic changes in hypertensive patients: a systematic review and meta-analysis of randomized controlledclinicaltrials. thejournalofclinicalhypertension, 18(4); 342–351 © 2023 the authors. page 24 of 24 introduction experimental section materials methods result and discussion strand geometry conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 4, october 2021 research paper analysis of information service pricing scheme model based on customer self-selection indrawati1, fitri maya puspita1*, resmadona1, evi yuliza1, oki dwipurwani1, sisca octarina1 1mathematics department, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30662, indonesia *corresponding author: fitrimayapuspita@unsri.ac.id abstractthis study attempts to analyze pricing schemes with monitoring cost and marginal cost for perfect substitute and quasi-linear utilityfunctions for achieving internet service provider (isp) in gaining benefit. two types of customers analyzed, namely customers whoare heterogeneous (both high-end and low-end) as well as heterogeneous customers (high-demand and low-demand) based onflat-fee, usage-based, and two-part tariff are the three types of pricing methods employed. the results show that usage-basedpricing schemes gain maximum profit optimal for heterogeneous customers (high-end and low-end), while for heterogeneouscustomers (high-demand and low-demand) type of pricing scheme two-part tariff obtains maximum profit optimal. the results ofthis study are more directed to the lemma of the perfect substitute utility function which compares the lemma of heterogeneouscustomers. this model was solved using lingo 13.0 software and isp to get maximum profit. keywordsutility function, perfect substitute, marginal cost, monitoring cost, pricing schemes, heterogeneous customers received: 25 july 2021, accepted: 14 october 2021 https://doi.org/10.26554/sti.2021.6.4.337-343 1. introduction internet is a tool for technology that can be used to reach the information needs of its customers. internet service providers or isps try to share the best capacity to internet users and to achieve the highest revenue (indrawati et al., 2015). bundling is a strategy carried out by combining two or more specic products into a sales package (gu et al., 2011; kopczewski et al., 2018; yassine et al., 2018; ye et al., 2017). the utility function sitepu et al. (2016) is usually related to the satisfaction level that users receive compensation for the use of information services, especially those related to maximizing prots in achieving certain goals and namely as a = i(m1, m2, . . . , mn̂) which means that m1, m2, . . . , mn̂ contribute user utility (kuo and liao, 2007; merayo et al., 2017) indicating goal-satisfaction. further research on current internet pricing schemes has involved other utility functions that are often used such as the original cobb-douglas utility function (puspita et al., 2020b; sitepu et al., 2017b), quasi-linear, perfect substitute (sitepu et al., 2017a), and bandwidth function (guan et al., 2008; indrawati et al., 2015; zu-xin et al., 2009; moriya et al., 2005) utilized in three types of information service pricing systems, namely at-fee, usage-based and two-part tari (gizelis and vergados, 2010; puspita et al., 2020a; puspita et al., 2021) both analytically and as minlp (mixed integer nonlinear programming) (barrios and cruz, 2017; giraldo, 2017) with the help of lingo (cunningham and schrage, 2004; schrage, 2009) application software. the perfect substituteutilityfunctionwasone importantutilityfunction to be selected to measure the satisfaction of the customers due to its linearity. the utility function is measurements of customer satisfaction indirectly (hitt and chen, 2005). so far, past research focus on the pricing of information pricing schemes have been conducted (indrawati et al., 2014; sitepu et al., 2017b; sitepu et al., 2017a; wu and banker, 2010) and also with the added parameters such as marginal dan monitoring costs. however, this research only focus on the pricing for information services without considering customer self-selection (rabbani et al., 2017). customer self-selection is based on packages or schemes (varadarajan, 2020) to be oered to various customers (rabbani et al., 2017). in this recent situation, customer self-selection through products or servicesoered iscriticalandneeds tobedeveloped, so it causes a gap that has to be explored more. the research needs to be critically explained in detail to show the relationship between the pricing scheme of information service and the ability of customers to select its service (zhou et al., 2020). then, our contribution will be exploring new formulations through lemmas to show which pricing methods provide the https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.4.337-343&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.4.337-343 indrawati et. al. science and technology indonesia, 6 (2021) 337-343 most eective models that can be adopted by customers based on his/her preferences (li et al., 2013). the customers can choose theschemes, due to itsheterogeneity(caiati etal.,2020; kopczewski et al., 2018; zhang et al., 2018). 2. method in this study, the customer self-model that the model was designed to have the eligibility of a customer to choose his/her preference pricing schemes tted with his/her needs and budget, was compiled and validated using a local data server with a perfect substitute utility function, then the optimal results could be compared. the steps are listed as follows: 1. modeling a pricing structure for the information services based on a quasi-linear utility function with at-fee, usage-based, and two-part tari pricing types for heterogeneous customer problems. a) for service pricing schemes on at-fee, b) for service pricing schemes on usage-based, c) for service pricing schemes on two-part tari 2. applying the scheme for optimal pricing based on data on the local server in the form of trac data. processing this data from a local server in the form of trac data on the lpse application, concerning with tool equipment available for the institution. 3. validating a quasi-linear utility function for diverse customer types based on three types of pricing schemes: at-fee, usage-based, and two-part tari, with the addition of marginal expenses and monitoring costs. 4. comparingthepricingschememodelsobtainedfromthe analysis in step 3 to obtain the optimal pricing scheme for each type of customer, namely high-end and lowend and high-demand and low-demand heterogeneous customers. 5. make conclusions and get the best information service pricing solutions. 3. results and discussion 3.1 perfect substitute utility functions for high-end and low-end customers in this instance, the perfect substitute utility function with the form a(m, n) = xm + yn. suppose there are high-end customers ( j = 1) and low-end customers ( j = 2) where 𝛼1 + 𝛼2 = 1 customer problem optimization: max m , n , o op = xm+yn−rmm−rnn−ro−(m+n)k (1) with constraints: m ≤ m̄o (2) n ≤ n̄o (3) xm + yn − rmm − rnn − ro − (m + n)k ≤ 0 (4) o = 0 or 1 (5) where rm is isp’ xed price in peak hour, rn is isp’ xed price in o peak hour, o is the customer decision to join the schemes or not, k is marginal and monitoring cost, m is the largest amount of data consumed during peak hours, measured in kilobytes and n is the maximum level of usage in kilobytes during o-peak hours. service provider problem optimization: max r, rm , rn ∑︁ j (rmm∗ + rnn∗ + ro∗) (6) where (m∗, n∗, o∗) = argmax xm +yn −rmm −rnn −ro− (m + n)k subject to equation (2)-(5). where r is customer fees for joining the service. the objective function (6) is used to maximize user overload according to the price set by the service provider. this model does not consider the initial cost for customers to join. but through this model can consider the long-term relationship between providers services and customers but does not charge for the short term or a certain period of time. o=0 or 1 is determined by the costumer, where if the customer chooses not to join the program then will be 0 so that m ≤ m̄o and m ≤ m̄o will be worth 0. meanwhile, if the customer chooses to join the program, then o will be worth. the value of m and n can not exceed the limit of m̄ and n̄. for usage-based and two-part tari pricing schemes: customer problem optimization: max m , n , o op = xm+yn−rmm−rnn−ro−(k+l)m−(k+l)n (7) subject to equation (2)-(3), and (5), also xm +yn −rmm −rnn −ro− (k+l)m − (k+l)n ≥ 0 (8) service provider problem optimization: max r, rm , rn ∑︁ j (rmm∗ + rnn∗ + ro∗) (9) where (m∗, n∗, o∗) = argmax xm +yn −rmm −rnn −ro− (k + l)m − (k + l)n subject to equation (2), (3), (5), and (8). case 1: flat-fee pricing scheme for heterogeneous customers (high-end and low-end) based on a perfect substitute utility function with marginal costs and monitoring costs maxr𝛼1(ro∗1) + 𝛼2(ro ∗ 2) = 𝛼1(x2m̄ + y2n̄ − (m + n)k) + 𝛼2 (x2m̄ + y2n̄ − (m + n)k) = (𝛼1 + 𝛼2)(x2m̄ + y2n̄− (m + n)k) © 2021 the authors. page 338 of 343 indrawati et. al. science and technology indonesia, 6 (2021) 337-343 the maximum benets for the service provider will be (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (m + n)k); where m is the number of highend customers and n is the numberof low-end customers. this analysis is summed up in lemma 1. lemma 1: if the isp uses a at-fee pricing scheme, the price charged to customers will be x2m̄ + y2n̄ − (m + n)k and the maximum prot earned is (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (m + n)k). case 2: a usage-based pricing is method based on a perfect substitute utility function for heterogeneous users (high-end and low-end) with marginal costs and monitoring costs. if the isp chooses to use a usage-based pricing scheme, then it is set to rm > 0, rn > 0, and r = 0, so that the optimization of customer problems becomes: max mj , nj , oj op =xjmj + yjnj − rmmj − rnnj − r(0) − (k + l) mj − (k + l)nj max mj , nj , oj op = xjmj+yjnj−rmmj−rnnj−(k+l)mj−(k+l)nj optimization of high-end heterogeneous customer problems: to maximize equation (6), a dierentiation is made to the lowend heterogeneous customer optimization problem as follows. to maximize the equation, a dierentiation is made to m1 and n1; under the conditions of 𝜕op 𝜕m1 = 0 and 𝜕op 𝜕n1 = 0 ↔ 𝜕(x1m1 + y1n1 − rmm1 − rnn1 − (k + l)m1 − (k + l)n1) 𝜕m1 = 0 ↔ x1(k + l) = rm and ↔ 𝜕(x1m1 + y1n1 − rmm1 − rnn1 − (k + l)m1 − (k + l)n1) 𝜕n1 = 0 ↔ y1(k + l) = rm service provider problem optimization becomes: max r, rm, rn 𝛼1(rmm∗1 + rnn ∗ 1) + 𝛼2(rmm ∗ 2 + rnn ∗ 2) = max rm, rn 𝛼1((x1 − (k + l))m∗1 + (y1 − (k + l))n ∗ 1) +𝛼2((x2 − (k + l))m∗2 + (y2 − (k + l))n ∗ 2) = max rm, rn 𝛼1(x1m∗1 + y1n ∗ 1 − (k + l)m ∗ 1 − (k + l)n ∗ 1) +𝛼1(x2m∗2 + y2n ∗ 2 − (k + l)m ∗ 2 − (k + l)n ∗ 2) in order to maximize the optimization equation for the producer problem, the isp must minimize the value of rm and rn. since m1, m2, n1, and n2 are constrained, m∗1 , m ∗ 2 , n ∗ 1, and n∗2 cannot exceed m̄ and n̄.to nd the maximum cost, analysis during peak hours has been done. this analysis is applied to problems during peak and o-peak hours. specically, rm and rn will be rm = x2 − (k + l) and rn = y2 − (k + l) with the maximum prot obtained is: (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (k + l)m̄ − (k + l)n̄). based on this case, the following lemma 2 is obtained. lemma 2: if isp utilizes the usage-based pricing scheme, the optimal prices will be rm = x2 − (k + l) and rn = y2 − (k + l) with the maximum prot gained is (𝛼1 + 𝛼2)(x2m̄ +y2n̄ − (k + l)m̄ − (k + l)n̄). case 3: two-part tari pricing scheme for heterogeneous customers (high-end and low-end) based on a perfect substitute utility function with marginal costs and monitoring costs. if isp chooses to select a two-part tari scheme then it will be set rm > 0, rn > 0, and r > 0. then, rm will be obtained that ranges between x1 − (k + l) and x2 − (k + l) or x2 − (k + l) ≤ rm ≤ x1 − (k + l) and so does rn. the best price for rm should be between x1 and x2. when the prices are within this interval thenthehigh-endcustomerdemandswillbexedatm̄ andlowend customer demands will be proportional to a price decrease. meaning, rm and rn will be rm = x2 − (k+ l), rn = y2 − (k+ l), and r = 0. assume that x1 < 𝛼1+𝛼2 𝛼1 x2 and y1 < 𝛼1+𝛼2 𝛼1 y2. then, the isp problem will be: max px , py 𝛼1(rmm∗1 + rnn ∗ 1 + ro ∗ 1) + 𝛼2(rmm ∗ 2 + rnn ∗ 2 + ro ∗ 2) 𝛼1((x2 − (k + l))m∗1 + (y2 − (k + l))n ∗ + 0) +𝛼2((x2 − (k + l))m∗2 + (y2 − (k + l))n ∗ + 0) 𝛼1(x2m∗ − (k + l)m∗ + y2n∗ − (k + l)n∗) +𝛼2(x2m∗ − (k + l)m∗ + y2n∗ − (k + l)n∗) = (𝛼1 + 𝛼2)(x2m∗ + y2n∗ − (k + l)m∗ − (k + l)n∗) the maximum prot will be (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (k + l)m̄ − (k + l)n̄) then, this analysis is to be summarized in lemma 3. lemma 3: if isp uses a two-part tari scheme, the optimal price will berm = x2−(k+l), pn = y2−(k+l), andr=0 with the maximum prot of (𝛼1 +𝛼2)(x2m̄ +y2n̄ − (k+l)m̄ − (k+l)n̄). 3.2 perfect substitute utility function for high-demand and low-demand heterogeneous customers with a maximum degree of usage, it is assumed that there are two sorts of customers: high-demand customers (type 1) and low-demand customers (type 2) m̄1, and n̄1 for (type 1) and m̄2 and n̄2 for (type 2) where m̄1>m̄2 and n̄1>n̄2. suppose there are m high-demand customers and n low-demand customers with x1 = x2 = x and y1 = y2 = y. then, determination of the maximum prot on each pricingscheme used bythe isp. case 4: flat-fee pricing scheme for heterogeneous customers (high-demand and low-demand) based on a perfect substitute utility function with marginal costs and monitoring costs. if using a at-fee pricing scheme, it is determined that rm = 0, rn = 0, and r > 0. this means that if customers © 2021 the authors. page 339 of 343 indrawati et. al. science and technology indonesia, 6 (2021) 337-343 choose to join the given program, then the maximum level of satisfaction is obtained by choosing the level of consumption with the maximum level of satisfaction obtained will be m1 = m̄1, n1 = n̄1, or m2 = m̄2, n2 = n̄2xm̄1 + yn̄1 − (m̄1 + n̄1)k or xm2 + yn̄2 − (m̄2 + n̄2)k. so, isp cannot charge more than xm̄1 + yn̄1 − (m̄1 + m̄1)k to every high-demand customer and every low-demand customer am̄2 + bn̄2 − (m̄2 + n̄2)k. by using a at-fee pricing scheme, isps cannot distinguish pricing between high-demand customers and low-demand customers, so isps must choose to charge a fee of xm̄1 +yn̄1 − (m̄1 +n̄1)k and only high-demand customers can use the service or charge a fee of xm̄2+yn̄2−(m̄2+n̄2)k where high-demand customers and low-demand customers can join the given program. if it is assumed that 𝛼1[xm̄1 +yn̄1 − (m̄1 +n̄1)k] < (𝛼1 + 𝛼2)[xm̄2 + yn̄2−(m̄2+n̄2)k], thenthebestprice thatcanbechargedbythe isp is xm̄2 + yn̄2 − (xm̄2 + yn̄2)k for high-demand customers and low-demand customers. so, the maximum prot that the isp obtained is: (𝛼1 + 𝛼2)(xm̄2 + yn̄2 − (m̄2 + n̄2)k) based on the analysis, the following lemma 4 is obtained. lemma 4: if the isp uses a at-fee pricing scheme, the fee paid becomes p = xm̄2 +yn̄2 − (m̄2 +bn̄2)k and the maximum prot obtained is: (𝛼1 + 𝛼2[xm̄2 + yn̄2 − (m̄2 + n̄2)k] case 5: based on a perfect substitute utility function, a usagebased pricing method for heterogeneous customers (high-demand and low-demand) is proposed with marginal costs and monitoring costs. if the isp chooses to use a usage-based pricing scheme, then it is determined that rm > 0, rn > 0, and r = 0. for optimization of the high-demand/low-demand customer problem results in: max m , n , o op = xmj+ynj−rmmj−rnnj−(k+l)mj−(k+l)nj optimization of high-demand heterogeneous customer problems: to optimize equation (7), dierentiate toward m1 and n1; with conditions as following. 𝜕op 𝜕m1 = 0 and 𝜕op 𝜕n1 = 0 ↔ 𝜕(xm1 + yn1 − rmm1 − rnn1 − (k + l)m1 − (k + l)n1) 𝜕m1 = 0 ↔ x(k + l) = rm and ↔ 𝜕(xm1 + yn1 − rmm1 − rnn1 − (k + l)m1 − (k + l)n1) 𝜕n1 = 0 ↔ y(k + l) = rn low-demand heterogeneous customer problem optimization: in order to optimize equation (7), a dierentiation is made to m2 and n2; with conditions 𝜕op 𝜕m2 = 0 and 𝜕op 𝜕n2 = 0 ↔ 𝜕(xm2 + yn2 − rmm2 − rnn2 − (k + l)m2 − (k + 2)n2) 𝜕m2 = 0 ↔ x(k + l) = rm and ↔ 𝜕(xm2 + yn2 − rmm2 − rnn2 − (k + l)m2 − (k + 2)n2) 𝜕n2 = 0 ↔ y(k + l) = rn then, the service provider problem can be derived as follows: max p , px, py 𝛼1(rmm∗1 + rnn ∗ 1) + 𝛼2(rmm ∗ 2 + rnn ∗ 2) = 𝛼1(xm∗1 + yn ∗ 1 − (k + l)m ∗ 1 − (k + l)n ∗ 1) + 𝛼2(xm ∗ 2 + yn ∗ 2 − (k + l)m∗2 − (k + l)n ∗ 2) if m1, m2, m1, and m2 are limited, then m∗1 , m ∗ 2 , n ∗ 1, and n∗2 will be m̄1, m̄2, n̄1, and n̄2. then, rm, and ry will be rm = x − (k + l), and rn = y − (k + l) with the maximum prot of 𝛼1(xm̄1 + yn̄1 − (k + l)m̄1 − (k + l)n̄1) + 𝛼2(xm̄2 + ym̄2 − (k + l)m̄2 − (k + l)n̄2). this analysis is concluded in the following lemma. lemma 5: if the isp uses a usage-based pricing scheme, the optimal price is rm = x − (k + l), and rn = b − (k + l) with the maximum prot obtained is: 𝛼1(xm̄1 + yn̄1 − (k + l)m̄1 − (k + l)n̄1) + 𝛼2(xm̄2 + yn̄2 − (k + l)m̄2 − (k + l)n̄2) case 6: two-part tari pricing scheme for heterogeneous customers (high-demand and low-demand) based on a perfect substitute utility function with marginal costs and monitoring costs. if the isp chooses to use a two-part tari pricing scheme, it will be determined that rm > 0, rn > 0, and r > 0. for the optimization process on the optimization of the problem of high-demand customers and low-demand customers, then xm̄j + yn̄j − rmm̄j − rnn̄j − r(1) − (k + l)m̄j − (k + l)n̄j ≥ 0 ↔ xm̄j + yn̄j − (x − (k + l))m̄j − (y − (k + l))n̄j − r − (k + l) m̄j − (k + l)n̄j ≥ 0 ↔ xn̄j + yn̄j − xm̄j + (k + l)m̄j − yn̄j + (k + l)n̄j − r − (k + l) m̄j − (k + l)n̄j ≥ 0 ↔ −r ≥ 0 ↔ r ≤ 0 because p cannot be negative or r < 0, then r = 0. © 2021 the authors. page 340 of 343 indrawati et. al. science and technology indonesia, 6 (2021) 337-343 table 1. recapitulation of pricing schemes for dierent customer types customer type pricing scheme prot heterogeneous: high-end flat fee (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (m̄ + n̄)k & low-end usage-based (𝛼1 + 𝛼2)(x2m̄ + y2n̄ − (k + l)m̄ − (k + l)n̄)two-part tari heterogeneous: high-demand flat fee (𝛼1 + 𝛼2)(xm̄2 + yn̄2 − (m̄2 + n̄2)k usage-based 𝛼1(xm̄1 + yn̄1 − (k + l)m̄1 − (k + l)n̄1)+ & low-demand two-part tari 𝛼2(xm̄2 + yn̄2 − (k + l)m̄2 − (k + l)n̄2) therefore, the service provider problem will be max r, rm, rn 𝛼1(rmm∗1 + rnm ∗ 1 + r) + 𝛼2(rmm ∗ 2 + rnn ∗ 2 + r) = max r, rm, rn 𝛼1((x − (k + l))m∗1 + (y − (k + l))n ∗ 1 + r) +𝛼2((x − (k + l))m∗2 + (y − (k + l))n ∗ 2 + r) = max r, rm, rn 𝛼1(xm∗1 + yn ∗ 1 − (k + l)m ∗ 1 − (k + l)n ∗ 1) +𝛼2(xm∗2 + yn ∗ 2 − (k + l)m ∗ 2 − (k + l)n ∗ 2) if m1, m2, n1 and n2 are constrained, then m∗1 , m ∗ 2 , n ∗ 1 and n∗2 will be m̄1, m̄2, n̄1 and n̄2. in other words, rm = x − (k + l), rn = y − (k + l), and r = 0 with the maximum prot obtained is: 𝛼1(xm∗1 + yn ∗ 1 − (k + l)m ∗ 1 − (k + l)n ∗ 1) + 𝛼2(xm ∗ 2 + yn ∗ 2 − (k + l)m∗2 − (k + l)n ∗ 2) so, the following lemma is summarized. lemma 6 : if the isp uses a two-part tari pricing scheme, the optimal price is rm = x − (k + l), rn = y − (k + l), and r = 0 with the maximum prot obtained is: 𝛼1(xm∗1 + yn ∗ 1 − (k + l)m ∗ 1 − (k + l)n ∗ 1) + 𝛼2(xm ∗ 2 + yn ∗ 2 − (k + l)m∗2 − (k + l)n ∗ 2) table1displays themaximumprotgainedforeachscheme. by setting the parameter values assigned for each parameter as stated in table 2, the values for each prot can be determined. the value of m̄ and n̄ is collected from the average demand of bandwidth consumption of lpse trac data from a local server in one of the institutions in palembang for one month at the beginning of march 2021. the data is not used to build the model, but the data is for the validation model only. the data value is used to show or to validate the value obtained from the formulation for each lemma. table 2 depicts the values. where m̄1 = m̄ is the largest amount of data consumed during peak hours, measured in kilobytes. m̄2 without obtaining data is the maximum consumption rate during peak hours x̄1, so m̄1>m̄2. table 2. the values of m̄ and n̄ from lpse trac data notation ipse m̄1 or m̄ (kilobyte) 0.00185874 m̄2 (kilobyte) 0.061958 n̄1 or n̄(kilobyte) 0.00181696 n̄2 (kilobyte) 0.060565 n̄1 or n̄ is the maximum level of usage in kilobytes during o-peak hours. n̄2 is the greatest rate of consumption during o-peak hours, excluding data retrieval ȳ1 , so n̄1>n̄2. based on table 3, the maximum prot obtained is in the at-fee pricingscheme, which is equal to (𝛼1+𝛼2 )(0.00185874 x2 + (0.00181696)y2 − 0.0036757k) for high-end and lowend heterogeneous customers. meanwhile, for high-demand and low-demand heterogeneous customers, the maximum prot is by utilizing usage-based and two-part tari schemes, that are 𝛼1(0.061958x + 0.060565y − 0.128525k(k + l)) + 𝛼2(0.061958x + 0.060565y − 0.128525k(k + l)) 4. conclusions this paper focuses on how to design a model based on customer self-selection on deciding which pricing scheme suit for heterogeneous customers. the data of the local server of lpse is used to show the validation of the model that can be solved. based on the results of the analysis and discussion, it can be concluded as follows. the best pricing scheme for heterogeneous customers (high-end and low-end) is found using a at fee pricing scheme, while pricing strategies for heterogeneous customer (high-demand and low-demand) is obtained using a pricing scheme based on the perfect substitute utility function. the most optimal was usage-based with the customers can be satised by selecting the schemes on his/her preferences. for further research, the concept of bundling strategy is likely to be considered in the schemes due to its advantages more customers to choose the service. © 2021 the authors. page 341 of 343 indrawati et. al. science and technology indonesia, 6 (2021) 337-343 table 3. recapitulation of pricing schemes for dierent customer types customer type pricing scheme prot heterogeneous: high-end flat fee (𝛼1+𝛼2 )(0.00185874x2 + (0.00181696)y2 − 0.0036757k) & low-end usage-based (𝛼1+𝛼2 )(0.00185874x2 + (0.00181696)y2 − 0.0036757(k + l))two-part tari heterogeneous: high-demand flat fee (𝛼1 + 𝛼2)(0.061958x + 0.060565y − 0.128525k) usage-based 𝛼1(0.061958x + 0.060565y − 0.128525k(k + l))+ & low-demand two-part tari 𝛼2(0.061958x + 0.060565y − 0.128525k(k + l)) 5. acknowledgement on november 23, 2020, dipa of the public 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selection: from a chinese air consumer perspective. research in transportation business and management, 37; 100486 zu-xin, l., w. wan-liang, and x.-m. cheng (2009). optimal bandwidth scheduling for resource-constrained networks. acta automatica sinica, 35(4); 443–448 © 2021 the authors. page 343 of 343 introduction method results and discussion perfect substitute utility functions for high-end and low-end customers perfect substitute utility function for high-demand and low-demand heterogeneous customers conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 6, no. 3, july 2021 research paper chemical characterization of secondary metabolite from the endophytic fungus trichordema reecei isolated from the twig of syzygium aqueum ummi h. habisukan1,2, elfita3*, hary widjajanti4, arum setiawan4 1universitas islam negeri raden fatah palembang, south sumatra, indonesia2graduate school of sciences, faculty of mathematics and natural sciences, university of sriwijaya,. jl. padang selasa no. 524, palembang 30139, south sumatra, indonesia3department of chemistry, faculty of mathematics and natural sciences, university of sriwijaya, jl. palembang prabumulih, indralaya, south sumatra, 30662 indonesia4department of biology, faculty of mathematics and natural sciences, university of sriwijaya, jl. palembang prabumulih, indralaya, south sumatra, 30662 indonesia *corresponding author: elfita69@gmail.com abstractendophyticfungiaremicroorganismsthatliveinplants,withoutnegativeeffectsandaremutuallyrelatedtohostingplants. explorationof bioactive compounds from endophytic fungi is easier and cheaper because they do not require a large area, a short growingtime, and uncomplicated mixed compounds. endophytic fungi are new and patent base secondary metabolites but they are notextensively characterized and investigated for the exploration of raw materials for drugs. the purpose of this study was to obtainantioxidant secondary metabolites from endophytic fungi that live in the syzygium aqueum medicinal plant. in this study, endophyticfungi were isolated from s. aqueum twigs and molecular identification. the secondary metabolites were isolated by chromatographicmethod and chemical structure identified by spectroscopy. antioxidant activity was evaluated by method 1,1diphenyl-2-picrylhydrazyl (dpph). phylogenetic analysis showed the endophytic fungi of s. aqueum twig have a high similarity with the trichordemareecei twig 19msr.b2.3. the secondary metabolites from the ethyl acetate extract of the liquid culture of the fungus were identifiedas (4-hydroxy-3-(4-hydroxyphenyl)-5-oxotetrahydrofuran-2-yl) methyl acetate with ic50= 75.13 `g/ml. the secondary metabolitescan be developed into starting molecules for potential antioxidant agents. keywordsendophytic fungus, trichordema reecei, syzygium aqueum, secondary metabolite, antioxidant activity received: 6 march 2021, accepted: 12 june 2021 https://doi.org/10.26554/sti.2021.6.3.137-143 1. introduction the endophytic fungi are microorganisms to colonize the host plant tissue (leaves, fruit, seeds, stems, and roots) without negative eects and having a mutuallybenecial relationship. plants have the function of protecting and providing nutrients for endophytic fungi. in turn, endophytic fungi will produce bioactive compounds that help the host plants improve nutritional status for growth, resistance to herbivores and diseases, and physical stress tolerance (specian et al., 2012; mbilu et al., 2018; el-hawary et al., 2020). endophytic fungi are the basis of many promising natural products with varied chemical structures, higher biodiversity, and attractive bioactivity. a few researchers focused on nding secondary metabolites from endophytic fungi because they have been identied as a storehouse of bioactive secondary metabolites such as antibiotics, antiviral, antiprotozoal, anti-diabetic antiparasitic, anticancer, antioxidant, and immunosuppressant compounds that can be used in the agricultural, pharmaceutical and food industries. these compounds are alkaloids, terpenoids, steroids, isocoumarin derivatives, lactones, quinones, avonoids, phenols, indole derivatives, lignins, tannins, anthraquinones, xanthones, phenylpropanoids, phenolic acids, and peptides (khan et al., 2019; manganyi and ateba, 2020). natural products based on endophytic fungi are considered as one of the most relevant sources of discovery and molecular diversity for new drugs. several studies show up to 51% of the bioactive metabolites produced from endophytic fungi have an unknown chemical structure. they can produce metabolites similar to those produced by the plant itself or new compounds produced by plants. this group of microbes represents a great potential in biotechnology for the discovery of new drugs (cruz et al., 2020; el-hawary et al., 2020). syzygium aqueum, known as water guava, is native to indonesia and malaysia. the parts of this plant are used for traditional medicine, such as drugs for gastrointestinal disorders, bleeding, diabetes, inammation, hypertension, antivirus, and analgesics. the use of this plant for medicine cannot be separated from https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2021.6.3.137-143&amp;domain=pdf https://doi.org/10.26554/sti.2021.6.3.137-143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 its phytochemical composition including avonoids, avonoid glycosides, chromone glycosides, terpenoids, steroids, tannins, phenols, phenyl glycosides, and acylphloroglucinol derivatives these compounds have activities as antioxidants, antidiabetic, anticancer, toxicity, antiviral, antibacterial, antifungal, antiinammatory and anthelmintic which functions in traditional medicine. this s. aqueum plant is rich in bioactive compounds, so it is a potential host to obtain endophytic fungi that produce bioactive compounds (aung et al., 2020; palanisamy et al., 2011; sobeh et al., 2018; osman et al., 2009). literature studies show that there are many bioactive components in this plant, but no research has been found on the isolation of endophytic fungi and their pure compounds from s. aqueum twigs. therefore, this paper describes the isolation and identication of endophytic fungi from the twigs of s. aqueum, followed by the isolation, identication, and evaluation of the antioxidant activity of these secondary metabolites. in this study, it is known whether the secondary metabolites of this endophytic fungus have the potential to be developed as a source of antioxidants. 2. experimental section 2.1 materials the chemicals used such as ethanol 70%, distilled h2o, sodium hypochlorite (naocl) (merck), growth medium for fungi: pda and pdb (merck), silica gel for gravity column (merck), tlc silica gel 60 f254 from merck (art.5554), dpph (sigmaaldrich), and organic solvents (merck). 2.2 plant material collection the twig of s. aqueum was collected from indralaya, ogan ilir regency, south sumatra, indonesia. plant identication was conducted at the biosystematics laboratory, biology, fmipa sriwijaya university, with herbarium id 237064. 2.3 isolation of endophytic fungal isolation of endophytic isolates followed the procedure by mbilu et al., 2018; habisukan et al., 2021 with a few modications. s. aqueum twig is washed under running water to remove impurities. the surface of the twigs was sterilized by immersing the plant material in 75% ethanol for 2 minutes followed by 4% naocl for 1 minute and then rinsed twice using sterile distilled water. the plant material is allowed to dry on sterile lter paper and then cut to size 2 × 0.5 cm. furthermore, three pieces were placed on a petri dish containing pda (200 g potato, 20 g dextrose, and 15 g agar in 1000 ml of h2o, supplemented with 100 mg/l of chloramphenicol). colonypuricationwasdonebyfurthersubculturing the fungal colonies in pda until pure isolates were acquired. 2.4 identication of endophytic fungal identication of endophytic isolates followed the procedure by yohandini et al., 2015 which is molecularly by comparing the similarity of sample sequences with a web-based database known as blast (basic local alignment search tool). 2.5 cultivation of endophytic fungal pure isolates of endophytic fungi were cultured at 6 asks containing 200 ml of pdb medium (consisting of 20 g dextrose monohydrate, 200 g potatoes, and 1 l (water). six mycelia agar plugs (5 × 5 mm2) were inoculated into each erlenmeyer and then incubated at room temperature under static conditions for four weeks. after the incubation was complete, the media was ltered and extracted three times using ethyl acetate. ethyl acetate extract was evaporated with a rotary evaporator until a concentrated extract (6.4 g) and stored in a glass bottle (gustianingtyas et al., 2020; elta et al., 2019). 2.6 antioxidant activity test by dpph method antioxidant activity test of ethyl acetate viscous extract using the dpph method following the procedure by budiono et al, 2019 with modication. the sample concentrations were prepared with variations of 200, 100, 50, 25, 12.5, 6.25, 0.0 `g/ml, and gallic acid as a positive control. the percentage of dpph absorption inhibition with the following formula: % inhibition = control absorbance sample absorbance control absorbance ×100% 2.7 isolation and identication of secondary metabolite the crude extracts were separated using column chromatography (stationary phase: silica gel) and eluted with a graded eluent (n-hexane: ethyl acetate: methanol). eluate droplets were collected every 10 ml in the vials and monitored by tlc analysis to group the vials into subfractions. the subfraction was identied as having secondarymetabolites, then puried by column chromatography until a pure compound was obtained. the structure was identied by nmr 1d and 2d (budiono et al., 2019). 3. results and discussion 3.1 isolation of endophytic fungal s. aqueum twig has isolated ef labeled with b11. the molecular identication yields sequence assembly 577 bp endophytic fungus b11 is as follows: ctcccaaaccccaatgtgaacgttaccaatctgttg cctcggcgggattctctgccccgggcgcgtcgcag ccccggatcccatggcgcccgccggaggaccaactc aaactcttttttctctccgtcgcggcttccgtcgcg gctctgttttacctttgctctgagcctttctcggcg accctagcgggcgtctcgaaaatgaatcaaaacttt caacaacggatctcttggttctggcatcgatgaaga acgcagcgaaatgcgataagtaatgtgaattgcaga attcagtgaatcatcgaatctttgaacgcacattgc gcccgccagtattctggcgggcatgcctgtccgag cgtcatttcaaccctcgaacccctccggggggtcg gcgttggggatcggcccctcaccgggccgcccccg aaatacagtggcggtctcgccgcagcctctcctgc gcagtagtttgcacactcgcaccgggagcgcggcg cggccacagccgtaaaacaccccaaactctgaaatg ttgacctcggatcaggtaggaatacccgctgaactt © 2021 the authors. page 138 of 143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 figure 1. phylogenetic tree of the endophytic fungal b11 aagcata. the strain b11 has the accession number mw52 7423. the endophytic fungal b11 had the highest homology with trichordemareecei twig 19msr.b2.3. phylogenetic analysis follows the method described shown in figure 1. 3.2 isolation and identication of secondary metabolite separation of concentrated etoac extracts 3.2 g (silica gel: 70-230 mesh; 50 g) obtained subfraction b (0.9 g) with a purple stain on tlc analysis. purication was done by column chromatography (silica gel 70-230 mesh; 20 g) with eluent n-hexane etoac (7:3 → 0:10) yielded two fractions (b1– b2). the b2 fraction (426 mg) was puried again by column chromatography until compound 1 (244 mg) was obtained. figure 2 shows the 1h-nmr spectrum of the isolated compound 1. the special characteristic of the para-substituted aromatic ring in compound 1 can be identied in the h-nmr spectrum by the presence of a double pair of aromatic proton signals at 𝛿h 7.74 and 8.20 ppm each of which has a value of j= 8.5 hz with two integration. another characteristic that can be identied from the c-nmr spectrum is the presence of a high-intensity carbon signal at 𝛿c 128.3 and 123.9 ppm for two carbons in the same chemical shift respectively. hmqc spectrum analysis showed that the two high-intensity carbons bind to aromatic protons equivalent at 𝛿h 7.74 and 8.20 ppm respectively. a methyl acetate-substituted cyclic lactone ringside group was identied by the presence of two carbonyl ester figure 2. the 1h-nmr spectra of compound 1 signals at 𝛿c 164.7 and 170.9 ppm respectively and a singlet signal at 𝛿h 2.00 ppm with triple integration for the methyl proton. two multiplet proton signals at 𝛿h 4.35 and 4.24 ppm are the methylene groups of the methyl ester which are strengthened by dept 135 and hmqc spectrum, which are bound to 𝛿c 63.9 ppm. the position of the phenol hydroxyl group was determined based on the 13c-nmr spectrum analysis. oxyaryl carbon at 𝛿c 150.6 ppm while the other hydroxyl groups in the lactone ring were identied as bound to carbon 𝛿c 67.4 ppm. 1h and 13c nmr spectrum shows that the basic structure of compound 1 is a para-substituted aromatic ring of which the hydroxyl group and ester. in acetone, the number of hydroxyl groups can be seen from the proton signal that is not bound to carbon. the hmqc spectrum (figure 3) shows the presence of seven single-bonded 1h-13c correlations, two correlations for aromatic rings and ve correlations for ester substituents. there are two uncorrelated protons 1h-13c one bond identied as aromatic hydroxy protons (𝛿h 7.68 ppm) and aliphatic hydroxyl protons (𝛿h 5.48 ppm). the hmbc spectrum in figure 4 shows that the ester group substituent is a pentacyclic lactone ring. methine carbon at 𝛿c 67.4 ppm (c-4’) binds a hydroxyl group that correlates 1h-13c three bonds with signal c-3’ and a methine proton which correlates two bonds with carbonyl carbon (c-5’). methine carbon at 𝛿c 71.2 ppm (c-2’) binds a methyl ester group is indicated by the 1h-13c correlation of two methylene proton bonds with c-2’ and the triple bond correlation with c-3’ and c carbonyl methyl ester. the cosy spectrum in figure 5 shows the aromatic protons at 𝛿h 7.74 ppm 1h-1h correlated three bonds with aro© 2021 the authors. page 139 of 143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 figure 3. the 13c-nmr (a) dept 135 (b), hmqc (d) spectra of compound 1 and hmqc correlation (d) matic protons at 𝛿h 8.20 ppm and correlated long distances with four bonds with methine protons at 𝛿h 4.45 ppm. furthermore, it was identied the correlation of 1h-1h three methine proton bonds at 𝛿h 4.45 ppm with methine protons at 5.26 ppm. this shows the two equivalent aromatic protons are in the ortho position. these results support the proposed structure that compound 1 is a para-substituted benzene ring that is directly attached to the lactone substituent methine carbon. compound 1 was identied as (4-hydroxy3(4-hydroxyphenyl)-5-oxotetra hydrofuran-2yl) methyl acetate. the molecular structure with the numbering of carbon atoms and the chemical shift placement of the carbon and protons is shown in figure 5. based on a literature study, compound 1 has a dierent phenyls structure with phenyls of s. aqueum and other syzygium spp. this shows that compound 1 is produced by endophytic fungi and the host does not have the gene to promote the compound. there is no genetic evolution between fungal genes and host genes in promoting their secondary metabolites. the trichodermaspp inhabiting healthytissues of host plants asendophytic fungi (eltaetal.,2014). endophytic fungi from trichoderma family can can produce a broad variety of bioactive compounds. ding et al., 2019 isolated an antibacterial compound derived from isocumarin, chromone derivatives, and lichexanthone from the endophytic fungus trichoderma harzianum isolated from the leaves of ficus elastic. harwoko et al., 2019 reported antifungal and cytotoxic compounds, namely dithiodiketopiperazines produced by the endophytic fungi trichoderma harzianum isolated from zingiber ocinale figure 4. the hmbc spectra (a) and hmbc correlation (b) of compound 1 figure 5. the cosy spectra (a) and cosy correlation (b) of compound 1 © 2021 the authors. page 140 of 143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 table 1. the nmr data of compound 1 no. c 𝛿c ppm 𝛿h ppm (σh. multiplicity. j (hz)) hmbc cosy 1 148.2 2 128.3 7.74 (1h, d, 8.5) 71.2; 128.3; 148.2 8.20; 4.45 3 123.9 8.20 (1h, d, 8.5) 123.9; 148.2; 150.6 7.74 4 150.6 5 123.9 8.20 (1h, d, 8.5) 123.9; 148.2; 150.6 7.74 6 128.3 7.74 (1h, d, 8.5) 71.2; 128.3; 148.2 8.20 2’ 71.2 5.26 (1h, m) 128.3; (150.6k) 4.45 3’ 55.1 4.45 (1h, d, m) 63.9 5.26 4’ 67.4 6.35 (1h, d, 1) 164.7 5’ 164.7 1” 170.9 2” 20.7 2.00 (3h, s) 170.9 3” 63.9 4.35 (1h, m) 55.1; 71.2; 170.9 4.24 (1h, m) 55.1; 71.2; 170.9 4’-oh 5.48 (1h, d, 4.5) 55.1 4-oh 7.68 (1h, br) figure 6. compound 1 as (4-hydroxy-3-(4-hydroxyphenyl)-5oxotetrahydrofuran-2-yl)methyl acetate (palanisamyet al., 2011)). besides that, taxol compounds from trichoderma sp. isolated from taxus chinensis (liu et al., 2009). five sesquiterpene compounds from trichoderma sp. from the stem of paeonia delavayi (wu et al., 2011), trichodermin compounds (4b-acetoxy-12, 13-epoxytrichothec-9-ene) from t. koningiopsis vm115 isolated from vinca plants have antifungal activity (leylaie and zafari, 2018). this trichodermin compound is also produced by the endophytic compound trichodermabrevicompactum isolated from alliumsativum (shentu et al., 2014). compound 1 has not been found in the endophytic fungus trichoderma sp. so that it can complete the chemical prole of the genus. compound 1 has moderate antioxidant activitywith a value of ic50 = 75.13 `g/ml, while gallic acid as a standard antioxidant has a value of ic50 = 11.45 µg / ml. however, higher antioxidant activity can be obtained by semisynthesis of compound 1 to produce phenyl similar to gallic acid. the oh group in the aromatic ring of compound 1 is ortho-directing figure 7. phenyls of s. aqueum and other emph syzygium spp (aung et al., 2020) figure 8. estimates semisynthesis reaction of compounds 1 to produce a new compound which is more active with the standard like structure antioxidant gallic acid © 2021 the authors. page 141 of 143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 so that the electrophilic reaction of nitration (2 mol hno3 / h2so4) is followed by reduction of the nitro group (fe/hcl) will produce two amine groups on both ortho sides of the hydroxyl group. the next step is the transformation of the amine functional group by reaction with cold nitrous acid (hono) in hcl solution to yield aryldiazonium chlorides (arn2+ci). displacement by -oh may be prepared from diazonium salts by reaction with hot aqueous acid. this series of reactions is estimated to produce the compound (4-hydroxy-5-oxo-3(3,4,5trihydroxyphenyl) tetrahydrofuran-2-yl) methyl acetate (figure 8) (fessenden and fessenden, 1982). 4. conclusions secondary metabolites isolated from t. reecei dierent from the secondary metabolites produced by its host. moreover, these secondary metabolites have never been found in the endophytic fungus trichoderma family. the antioxidant activity of this compound is classied as moderate, but the production process is easier and cheaper so that it can be turned into star molecules through asemisynthetic process to produce potential antioxidant compounds. 5. acknowledgement thisresearchwasfundedbydaftarisianpelaksanaananggaran (dipa) universitas sriwijaya, through unggulan profesi grants 2020, number 0009/un9/sk.lp2m.pt/2020, september 28, 2020. references aung, e. e., a. n. kristanti, n. s. aminah, y. takaya, and r. ramadhan (2020). plant description, phytochemical constituents and bioactivities of syzygium genus: a review. a review de gruyter open chemistry, 18(1); 1256–1281 budiono, b., e. elta, m. muharni, h. yohandini, and h. widjajanti (2019). antioxidant activity of syzygium samarangense l. and their endophytic fungi. molekul, 14(1); 48–55 cruz, j. s., c. a. da silva, and l. hamerski (2020). natural products from endophytic fungi associated with rubiaceae species. journal of fungi, 6(3); 128 ding, z., t. tao, l. wang, y. zhao, h. huang, d. zhang, m. liu, z. wang, and j. han (2019). bioprospecting of novel and bioactive metabolites from endophytic fungi isolated from rubber tree ficus elastica leaves. journal of microbiology and biotechnology, 29(5); 731–738 el-hawary, s. s., a. s. moawad, h. s. bahr, u. r. abdelmohsen, and r. mohammed (2020). natural product diversity from the endophytic fungi of the genus aspergillus. royal society of chemistry advances, 10(37); 22058–22079 elta, munawar, muharni, and m. a. sudrajat (2014). identication of new lactone derivatives isolated from trichoderma sp., an endophytic fungus of brotowali (tinasporacrispa). hayati journal of biosciences, 21(1); 15–20 elta, e., j.e.larasati, andh.widjajanti (2019). antibacterial activityofcordylinefruticosa leafextractsanditsendophytic fungi extracts. biodiversitas journal of biological 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248–254 sobeh, m., m. f. mahmoud, g. petruk, s. rezq, m. l. ashour, © 2021 the authors. page 142 of 143 habisukan et. al. science and technology indonesia, 6 (2021) 137-143 f. s. youssef, a. m. el-shazly, d. m. monti, a. b. abdelnaim, and m. wink (2018). syzygiumaqueum: apolyphenolrich leaf extract exhibits antioxidant, hepatoprotective, painkilling and anti-inammatory activities in animal models. frontiers in pharmacology, 9(566); 1–14 specian, v., m. h. sarragiotto, j. a. pamphile, and e. clemente (2012). chemical characterization of bioactive compounds from the endophytic fungus diaporthe helianthi isolated from luehea divaricata. brazilian journal of microbiology, 43(3); 1174–1182 wu, s.-h., l.-x. zhao, y.-w. chen, r. huang, c.-p. miao, and j. wang (2011). sesquiterpenoids from the endophytic fungus trichoderma sp. pr-35 of paeonia delavayi. chemistry and biodiversity, 8(9); 1717–1723 yohandini, h., julinar, and muharni (2015). isolation and phylogeneticanalysisof thermophilecommunitywithintanjung sakti hot spring, south sumatera, indonesia. hayati journal of biosciences, 22(3); 143–148 © 2021 the authors. page 143 of 143 introduction experimental section materials plant material collection isolation of endophytic fungal identification of endophytic fungal cultivation of endophytic fungal antioxidant activity test by dpph method isolation and identification of secondary metabolite results and discussion isolation of endophytic fungal isolation and identification of secondary metabolite conclusions acknowledgement subject index vol. 2 no.4 october 2017 b bamboo biomonitoring c capryol-90 citric acid solution congo red d distribution e edible film environmental conditions f furosemide h heavy metal hepatoprotection m maps matoa leaves (pometia pinnata) microalgae modification starch mura o odonata p paracetamol peg-400 pineapple extract polysorbate-80 procion red propylene oxide s silymarin snedds spirulina sp u uwi starch (dioscorea alata l) title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper study of anthocyanin extraction from red banana (musa sapientum l. var rubra) waste and characteristics of light effects yessy rosalina1,3, endang warsiki2*, annas miftah fauzi2, illah sailah2 1agroindustrial technology study program, graduate school of ipb university, bogor, 16680, indonesia2department of agroindustrial technology, faculty of agriculture technology, ipb university, bogor, 16680, indonesia3department of agroindustrial technology, faculty of agriculture, university of bengkulu, bengkulu, 38371, indonesia *corresponding author: endangwarsiki@ipb.ac.id abstractanthocyanins are compounds responsible for plants’ blue, purple, violet, magenta, red, and orange colours. anthocyanins are foundin tropical fruits. generally, anthocyanins are found in the peel tissues of plants. the increasing interest in anthocyanins, especially inthe field of food and health, supports the development of anthocyanin exploration research. one of the uses of anthocyanins thatare widely developed today is the addition of anthocyanins as indicators in smart packaging. for application on the packaging, inaddition to extraction techniques, it is also necessary to assess the characteristics of anthocyanins in the environment. this studyaims to examine the anthocyanin potential of red banana waste and the effect of light on anthocyanin stability. the anthocyaninsobserved are the result of anthocyanin extraction from the red banana peel and bracts using the maceration method. the solventused is water acidified with citric acid. the study results showed that the total anthocyanin content in red banana bracts extractwas higher than in extract from red banana peel. a concentrated extract from the bracts of a red banana contains 114.26 `g/g fwof total anthocyanins. in comparison, the concentrated extract of red banana peel contains 110.27 `g/g fw of total anthocyanins.identification of concentrated extracts of red banana peel and flower through ftir test, maximum wavelength test with uv-vis anddiscolouration test showed that the extract contains anthocyanin compounds. irradiation with a 25-watt bulb lamp, uv lamp andsunlight on concentrated extracts of the red banana peel and bracts showed degraded anthocyanin content. the results of this studyshow that the peel and flower of red bananas have the potential to be developed as a source of anthocyanins. keywordsred banana (musa sapientum l. var rubra), red banana peel, characteristics received: 23 august 2022, accepted: 29 october 2022 https://doi.org/10.26554/sti.2022.7.4.522-529 1. introduction anthocyanins are compounds belonging to the avonoid group. the colour and stability of anthocyanin pigments are inuenced by ph, oxygen, light, temperature, ascorbic acid, copigmentation, metal ions and structures (horbowicz et al., 2008; khoo et al., 2017; yang et al., 2015). the stability of anthocyanins is also inuenced by the b ring on the anthocyanin structure and the presence of hydroxyl or methoxyl groups (castañeda-ovando et al., 2009). the stability of the thermal properties of anthocyanins is inuenced by ph and temperature. the colour of anthocyanins will be stable at a lower ph. in addition to ph, anthocyanin discolouration also occurs as the temperature increases during storage (wu et al., 2018). interest in anthocyanins is increasing, both in the eld of food and health (martín et al., 2017; pina, 2014; santosbuelga et al., 2014). in the food industry, anthocyanins are no longer just a source of natural food colouring, but anthocyanins are starting to be widely applied as indicators of products in packaging. the development of technology demands a better packaging function. packaging no longer serves as a protector of the product, but also as a means of communication between producers and consumers. anthocyanins are compounds that have good performance in the development of active packaging. this is because anthocyanins contain potent antioxidants and have the potential to be antimicrobials. the addition of anthocyanins to the active packaging is perfect for ph-sensitive products. several research results show that anthocyanins are successfully used as indicators on the packaging. using chitosanpurple potato not only improves the physical properties of the lm produced but also has antioxidant properties. so, it is very suitable for product packaging that is easily oxidized https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.522-529&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.522-529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 (li et al., 2019). intelligent ph-sensor indicators based on nanocellulose bacteria and anthocyanins from black carrots show discolouration as the freshness of sh llets decreases (moradi et al., 2019). the use of anthocyanins from blueberry waste, red cabbage extract and aqueous hibiscus extract has been successfullyused as a ph indicator in smart packaging and intelligent food packaging (andretta et al., 2019; jiang et al., 2020; peralta et al., 2019). with the growing use of anthocyanins in the non-food industry, it is necessary to study potential anthocyanin sources. anthocyaninsareabundant intropical fruits (khooetal.,2017). some sources of anthocyanins that are commonly found in indonesia include purple sweet potatoes contain 2.57±0.86 mg/g total anthocyanin (arisanti et al., 2020), dragon fruit containing 104.58 mg/kg total anthocyanin (kwartiningsih et al., 2016), rosella owers contain 9.43 mg/g total anthocyanin (lestari et al., 2019), red spinach contain 93.03 mg/g total anthocyanin (narayanan et al., 2018) and and banana bracts contain 57.49 mg/100g total anthocyanin (begum and deka, 2017). according to martín et al. (2017) anthocyanins are abundantly contained in the fruit’s peel. research sujithra and manikkandan (2019) shows that banana leaves and other banana plant waste have the potential to be used as a source of anthocyanins and natural dyes. the study’s results fu et al. (2018) red banana peel contains six times more anthocyanins than yellow banana peel, which is 154.57 `g/g fw. red bananas have a proportion of fruit esh of 59.05±9.01 and fruit peels of 40.95± 9.01. the proportion of fruit skin is large enough that it has the potential to be used as a raw material in phytochemical processing. the red banana plant has the latin name musa acuminata colla red/musa acuminta colla red dacca (lim, 2012). this plant has the synonym musasapientum l. var rubra (kasrina and zulaikha, 2013). in indonesia, red bananas have several names, including pisang merah, pisang udang, and pisang kidang. red banana plants are identied through the red colour on petioles and bones of leaves, tree trunks and owers are red. unripe red banana fruits will be dark red and will turn into a red-orange colour by the time the fruit ripens. the fruit’s esh is milky white with a sweet taste when the fruit is ripe. therefore, it is necessary to begin to develop the use of anthocyanins from the waste of the red banana plant. the use of waste in the non-food industry will be more protable because it will not interfere with food sources. the purpose of the study was to examine the anthocyanin potential of red banana waste and the eect of light on anthocyanin stability. the anthocyanins observed result from anthocyanin extraction from the peel and bracts of a red banana. 2. experimental section 2.1 materials the materials used in this study were fresh peel and bracts of red banana (musa sapientum l. var rubra) taken from a farmer’s farm in bengkulu tengah regency, bengkulu province, indonesia, distilled water, kcl, ch3co2na.3h2o, hcl, citric acid and naoh. the tools used are a ph meter, glassware, uv-vis (thermo scientic genesys 150), ftir (alpha ft-ir spectrometer) and blender. 2.2 methods 2.2.1 physical and physico-chemical characterization of red banana fruit physical characterization is carried out by measuring the fruits of red bananas using callipers. the physicochemical characterization of red banana fruit is carried out through proximate tests of red banana fruit using the aoac method. 2.2.2 anthocyanin extraction anthocyanin extraction of red banana peel and bracts used a modication method (rosalina et al., 2022). fresh ingredients weighing 200 grams are mashed using a blender. extraction is carried out by mixing 200 gram of fresh material in 400 ml of water solvent. the solvent is acidied by adding 16 grams of citric acid. the extraction process is carried out by the maceration method for 36 hours. next, the solution is ltered using lter paper to remove coarse particles. the ltering process is continued by using a vacuum lter with whatman lter paper (no.01) to remove ne particles that are still dissolved. then it was centrifuged using a centrifuge at 3000 rpm for 15 minutes. the extract purication process is carried out using a vacuum rotary evaporator at a temperature of 50◦c. 2.2.3 identication of anthocyanin compounds identication of anthocyanin compounds in concentrated extracts of redbananapeel and bracts was carriedout using: ftir test, uv-vis test and colour change test using hcl solvents 2 m and naoh 2 m method harboone (1997) cited in lestario et al. (2014). 2.2.4 total anthocyanins measurement of the total anthocyanin content was calculated using the spectrophotometer method based on the ph dierence. this method was adopted by (giusti et al., 1999; giusti and wrolstad, 2001). red banana peel and bracts extract is diluted in a ph buer of 1.0 and a buer of 4.5. determine the dilution factor of the diluted extract at a ph buer of 1.0. the exact dilution factor of the sample is obtained maximum absorbance at a wavelength of 510 nm. furthermore, the absorbance of the solution at wavelengths of 510 nm and 700 nm was measured, using a uv-vis spectrophotometer. the absorbance value is calculated using equation 1. a = [(a510 − a700)ph 1.0 − (a510 − a700)ph 4.5] (1) information: a = absorbance value the total anthocyanin content is calculated using equation 2. total anthocyanins (mg/l) = (a × df × mw × 1000) y × l (2) © 2022 the authors. page 523 of 529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 information: a = absorbance value; df= dilution factor; mw= molecular weight (c12h21clo11. 449.2 g/mol); y= koef. molar absorpivity (26,900 l/mol.cm); l= width of the cuvet (1 cm). 2.2.5 light inuence test taken 3 ml of diluted anthocyanin extract. then the sample is illuminated with a light derived from a uv lamp, a 25watt incandescent lamp and sunlight. absorbance is measured every 6 hours and observed for 2 days. absorption is measured at a wavelength of 510 nm. 3. result and discussion 3.1 physical and physico-chemical characterization of red banana fruit the raw materials used in this study were fresh red banana peels and bracts. bananas are harvested when the fruit is ripe on the tree. when harvested, the skin colour of red bananas is still purple, slightly green at the base of the fruit. the bananas are ripened until the bananas are ripe, which is indicated by the colour of the skin turning red orange (figure 1). figure 1. red banana plant a) tree b) unripe fruit and ripe fruit c) banana flower bud the number of fruits is 12-15 pieces on each comb. the amount of hands of red banana are relatively less than other kind of banana. generally, it has 4-6 hands of banana. red bananas have a proportion of fruit esh of 59.05±9.01 and fruit peels of 40.95±9.01. the proportion of fruit peel is large enough that it has the potential to be studied as a raw material in phytochemical processing (kibria et al., 2019). proximate analysis is used to see the chemical content of the fruit. dierences in the degree of maturity of bananas aect the chemical content of the esh and peel of the fruit. the carbohydrate content shows signicant dierences in banana kepok from various levels of maturity (nurhalimah et al., 2019). research on the tongka banana fruit peel shows that the ripe peel has a higher protein, fat, and carbohydrate content than raw tongka banana peel (wakano et al., 2020). dierences in maturity levels also aect the anthocyanin content. research aurelia et al. (2021) shows that the more mature the peel of the coee fruit used, the more anthocyanin content also increases. the same results were also obtained in the studymoradinezhad et al. (2018) the anthocyanin content of barberry fruit increased as the maturity index of the fruit increased. a proximate analysis of red banana fruit is presented in table 1. table 1. characteristics of unripe banana fruit musa sapientum l. var rubra physical characteristics weight 226.520±16 g long 15.750±0.64 cm diameter 4.125±0.25 cm thick 4.750±0.50 cm physico-chemical characteristics moisture content (%) 3.58 ash content (%) 3.00 total protein (%) 1.23 total carbohydrates (%) 90.47 total fat (%) 0.48 fibre (%) 1.24 3.2 identication of anthocyanin compounds anthocyanins are water-soluble colour pigments. anthocyanin stability is inuenced by ph, light, temperature, and anthocyanin pigment structure. the presence of hydroxyl and methoxyl groups, as well as the presence of rings, also aect the stability of anthocyanins (khoo et al., 2017). the anthocyanin structure consists of three carbon atoms bonded by oxygen atoms to link the benzene ring (figure 2). figure 2. structure anthocyanin (castañeda-ovando et al., 2009) 3.2.1 ftir test the results of spectrum analysis using ftir are shown in figure 3 and table 2. ftir analysis aims to identify the content of compounds in the extract based on functional groups. according to swer et al. (2018), the characteristic anthocyanin compounds on the ftir spectra are characterized by the presence of functional groups o-h, c=o, c=c and c-o-c. the © 2022 the authors. page 524 of 529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 emergence of peak c=o vibration absorption on ftir spectra shows the characteristic anthocyanins (adu et al.). the functional group characteristics in the concentrated extract of the red banana are carried out at a wave number of 4000–600 cm−1 (figure 3). the concentrated extract of red banana shows o-h strain vibration in the absorption range of wave number 3596-3201 cm−1. the c=c group is observed in the absorption of wave numbers 1682–1502 cm−1. wave number absorption in the range of 1756–1691 cm−1 indicates the presence of the c=o group. c-o and c-h groups were identied in the absorption of wave numbers 1305-1059 cm−1 and 2963-2857 cm−1. the peak of absorption showing the c=o vibration typical of anthocyanins is detected at a wave number of 1732 cm−1 (table 2). figure 3. spectra ir extract concentrated (ftir analysis) the identicationof theo-h,c=o,c=candc-o-cfunctional groups on the ftir spectra shows that the concentrated extract of the red banana peel and bracts contains anthocyanin compounds. table 2. characteristics of anthocyanin absorption in ftir spectra absorption literature* functional area clusters 3351 3200–3600 o-h 1635 1500–1600 c=c aromatic 1732 1690–1760 c=o 1206 1050–1300 c–o alcohol *source: (skoog et al., 2018) 3.2.2 uv-vis test anthocyanins belong to the avonoid compound group, with the typical spectrum of band ii being in the range of 230-295 nm and a band i in the range of 300-560 nm. anthocyanin uv absorption is in the range of 270-280 nm (band ii) and 465-560 nm (a band i) (neldawati et al., 2013). the results of the uv-vis spectrophotometer analysis of the red banana peel and ower extract are presented in figure 4. figure 4 shows that the maximum wavelength of red banana peel and bract extract is 510 nm. these results show that the maximum wavelength of the extract corresponds to the characteristics of anthocyanins. it can be stated that the extract of red banana peel contains anthocyanin compounds. figure 4. maximum wavelength of concentrated extract of red banana peel and bracts 3.2.3 colour change test the colour change test is is to determine whether there is anthocyanin compounds in the concentrated extract of the red banana peel and bracts. the colour test was carried out using hcl 2 m and naoh 2 m compounds. concentrated extracts that experienced a steady red change if added hcl 2 m and the colour became green-blue when dripped with naoh 2 m showed that the extract contained anthocyanins (sani et al., 2018; meganingtyas and alauhdin, 2021; lestario et al., 2014; surianti et al., 2019). discolouration in anthocyanin extracts is associated with the acidic and alkaline conditions of the solution. the discolouration test on the concentrated extract of the red banana peel and bracts is presented in table 3. observational data showed that the colour of the concentrated extract of red banana peel and bracts changed after adding hcl and naoh. these results show that concentrated extracts contain anthocyanin compounds. based on the identication of anthocyanins in the concentratedextractof redbananapeel throughtheftirtest, uv-vis test, and extract discolouration test, it can be concluded that the extract contains anthocyanin compounds. 3.3 total anthocyanin content according to castañeda-ovando et al. (2009) the use of methanol solvents in the extraction of anthocyanins is more toxic. so, the use of anthocyanins in the food and pharmaceutical industries is limited. research tensiska and natalia (2006) shows that the use of acidied water as a solvent can extract anthocyanins with the highest value compared to using ethanol and ethyl acetate solvents in the anthocyanin extraction of arben fruit. the use of water as a solvent can be considered in green extraction. © 2022 the authors. page 525 of 529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 table 3. colour change test treatment change anthocyanins* the extract was heated at a temperatureof100◦cwith hcl 2 m±5 min the red colour does not fade + furthermore, the extract is dripped with naoh 2 m the red colour becomes bluishgreen which is land-fading + visible spectrum _max 505-535 nm _max 510nm *+: appropriate changes occur extraction using a water solvent acidied with citric acid on the red banana peel yielded a total anthocyanin of 110.27 `g/g fw. this result was slightly lower than the total anthocyanins of red banana peel in the study fu et al. (2018) using methanol solvent, which was 154.57 `g/g fw. this result show that the use of water acidied with citric acid was the potential to be applied to the anthocyanin extract of red banana peel. this was because the total anthocyanin is only a little bit dierent for the same type of banana though it used dierent solvent. the total anthocyanins extracted from red banana bracts using water as solvent were 114.26 `g/g fw. this result is lower than previous studies that used ethanol and methanol as solvents. total anthocyanins from the extraction of banana bracts (musa paradisiaca) were obtained by 321.4 `g/g fw (sujithra and manikkandan, 2019). anthocyanin extraction from banana bracts (musa abb) was processed with total anthocyanins of 569.8 `g/g fw (begum and deka, 2017), and research lestario et al. (2014) resulted in a total anthocyanin of 332 `g/g fw from the extraction of banana ower bracts (musaparadisiacal). this is due to the dierence in the polarity properties of the solvent and the type of banana used, thus affecting the total anthocyanins extracted (kitdamrongsont et al., 2008). the results of this study show that red banana fruit waste, namely red banana peel and bracts, has the potential to be a source of anthocyanins. red banana peel has a proportion of 40.95% per red banana. according to pazmiño-durán et al. (2001), during the harvest season, as much as 300 kg/ha of banana bract is disposed of as waste. the use of water as a solvent produces anthocyanins that are safe for food applications. the results of the study obtained that the total anthocyanin content in red banana bracts was higher than extract from red banana peel. table 4 shows the anthocyanin content of the peel and the bracts of the banana. this dierence is due to dierences in thecolourdensityof theextract in thepeelextract and red banana bracts. this can be seen from the absorbance value of the anthocyanin extract of the red bananabracts, which is higher than the peel red banana extract (figure 4). according to simmonds (1954), the colour of the banana bracts is related to variations in anthocyanin. table 4. total anthocyanin content in concentrated extract of red banana peel and bracts source anthocyanin total peel red banana 110.27 `g/g fw bracts red banana 114.26 `g/g fw 3.4 light eects the environment greatly aects the stability of anthocyanins. one of the factors that aect the stability of anthocyanins is light. the results showed that the rate of anthocyanin degradation from the peel and bracts of the red banana experienced a faster decrease when illuminated by light from a uv lamp compared to the light of a 25-watt bulb lamp. this result is in line with previous research, and here uv light is the main factor in the degradation of anthocyanins due to the presence of light (bąkowska et al., 2003; mohammadi et al., 2022). this shows that anthocyanins will degrade more quickly at higher ambient temperatures. based on observations, the ambient temperature illuminated by uv lamps is 36◦c, while the environment illuminated by 25-watt bulb lamps has an average temperature of 33◦c. the degradation of anthocyanins due to the presence of light followed the rst-order reaction model (figures 5, 6, and 7). the eect of light on anthocyanin degradation has been widely studied. storage of the anthocyanin extract of c. hirsutus fruit in light conditions drains faster than storage in dark conditions (rakkimuthu et al., 2016). research boo et al. (2012) showed that the anthocyanin degradation rate reached 30% when the anthocyanin extract was exposed to sunlight for only six hours. the degraded rosella anthocyanin extract showed a signicant colour change (wu et al., 2018). research mohammadi et al. (2022) shows that anthocyanin degradation depends on the numberof methoxyl groups orhydroxyl groups in. the highest anthocyanin degradation occurred in delphinidin 3-o-glucoside. delphinidin contains more hydroxyl groups. the number of dominant hydroxyl groups causes the colour to tend to be unstable. anthocyanin irradiation causes anthocyanin to be degraded. according to bąkowska et al. (2003) irradiation of anthocyanins in direct sunlight causes the highest rate of anthocyanin degradation. energy from light can trigger photochemical reactions (photooxidation) so that anthocyanins are degraded (nurtiana, 2019). the photochemical mechanism of anthocyanins due to light is due to the opening of carbon ring number 2 which will result in the formation of colourless compounds such as chalcone (hendry, 1996). this can be seen from the decrease in the absorbance value of the anthocyanin extract. the decrease in the absorbance value of the extract indicated the degradation process of anthocyanins. the degradation of colour in anthocyanins is caused by a change in red potassium avylium to colourless alkaline © 2022 the authors. page 526 of 529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 carbinol and ends up becoming colourless chalcone (markakis, 1982). visually, the degradation of anthocyanins can be seen from the reduction of the red colour in the extract to a light colour or fading. if there is an oxidizing agent, the colour of the extract will turn brown. in the anthocyanin structure, light has two dierent eects, namely increasing the rate of thermal degradation and triggering product formation through excited avylium (furtado et al., 1993). according to markaris et al. (1957), the initial stage of anthocyanin degradation is the opening of the pyrylium ring and the formation of chalcones. furthermore, the ring will be lost along with the formation of coumarin glycoside derivatives (patras et al., 2010). figure 5. the degradation rate of red banana peel anthocyanin extract figure 6. the degradation rate of red banana bracts anthocyanin extract the rate of degradation of anthocyanins in the peel and bracts of the red banana is higher if given direct sunlight. these results show that anthocyanins in the peel extract and bracts of the red banana are greatly aected by their stability in the presence of light in the environment. these results are in line with research (bakhshayeshi et al., 2006; mohammadi et al., 2022; rakkimuthu et al., 2016). figure 7. the degradation rate of anthocyanin anthocyanin in red banana peel and bracts in sunlight 4. conclusion extracts of red banana peel and bracts using water solvents acidied with citric acid are proven to contain anthocyanin compounds. the total anthocyanins in the concentrated extracts of the peel and bracts of the red banana were 110.27 `g/g fw and 114.26 `g/g fw, respectively. these results show that the peel and bracts of a red banana have the potential to be a source of anthocyanins. light aects the stability of anthocyanins. this is shown by the rate of anthocyanin degradation, which shows a downward trend. 5. acknowledgment the authors would like to thank the ministry of education and culture, research and technology which has funded this research through the doctoral dissertation research grant and lppmipbuniversitywhichhas facilitatedthe implementation of the research. references adu, r. e. y., g. gelyaman, and m. kabosu (). pemanfaatan ekstrak antosianin dari limbah kulit bawang merah (allium cepa) sebagai zat pemeka (sensitizer) pada dye sensitized solar cell (dssc). alchemy jurnal penelitian kimia, 18(1); 103–111 (in indonesia) andretta, r., c. l. luchese, i. c. tessaro, and j. c. spada (2019). development and characterization of ph-indicator films based on cassava starch and blueberry residue by thermocompression. food hydrocolloids, 93; 317–324 arisanti, c. i. s., c. b. a. c. sukawati, i. g. n. j. a. prasetia, and i. m. a. g. wirasuta (2020). stability of anthocyanins encapsulated from purple sweet potato extract aected by maltodextrin concentration. macromolecular symposia, 391; 1900127 aurelia, s. w., l. s. abirrania, and t. a. hariyadi (2021). penentuan tingkat kematangan biji kopi berdasarkan kandungan antosianin ditinjau dari daa dan warna kulit © 2022 the authors. page 527 of 529 rosalina et. al. science and technology indonesia, 7 (2022) 522-529 buah kopi. prosiding industrial research workshop and national seminar, 12; 140–144 (in indonesia) bakhshayeshi, m., m. khayami, r. heidari, and r. jamei (2006). the eects of light, storage temperature, ph and variety on stability of anthocyanin pigments in four malus varieties. pakistan journal of biological sciences, 9(3); 428–433 bąkowska, a., a. z. kucharska, and j. oszmiański (2003). the eects of heating, uv irradiation, and storage on stability of the anthocyanin–polyphenol copigment complex. food chemistry, 81(3); 349–355 begum, y. and s. deka (2017). stability of spray-dried microencapsulated anthocyanins extracted from culinary banana bract. international journal of food properties, 20(12); 3135–3148 boo, h. o., s. j. hwang, c. s. bae, s. h. park, b. g. heo, and s. gorinstein (2012). extraction and characterization of some natural plant pigments. industrial crops and products, 40; 129–135 castañeda-ovando, a., m. de lourdes pacheco-hernández, m. e. páez-hernández, j. a. rodríguez, and c. a. galánvidal (2009). chemical studies of anthocyanins: a review. food chemistry, 113(4); 859–871 fu, x., s. cheng, y. liao, b. huang, b. du, w. zeng, y. jiang, x. duan, and z. yang (2018). comparative analysis of pigments in red and yellow banana fruit. food chemistry, 239; 1009–1018 furtado, p., p. figueiredo, h. c. das neves, and f. pina (1993). photochemical and thermal degradation of anthocyanidins. journal of photochemistry and photobiology a: chemistry, 75(2); 113–118 giusti, m. m., l. e. rodríguez-saona, and r. e. wrolstad (1999). molarabsorptivityand colorcharacteristics of acylated and non-acylated pelargonidin-based anthocyanins. journal of agricultural and food chemistry, 47(11); 4631– 4637 giusti, m. m. and r. e. wrolstad (2001). characterization and measurement of anthocyanins by uv-visible spectroscopy. current protocols in food analytical chemistry, (1); f1–2 hendry, g. 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25–31 (in indonesia) wakano, d., d. e. sahertian, and t. telussa (2020). analisis nilai proksimat kulit buah pisang tongka langit (musa troglodytarum l.) pada beberapa tingkat kematangan buah. agritekno: jurnal teknologi pertanian, 9(2); 58–63 (in indonesia) wu, h. y., k. m. yang, and p. y. chiang (2018). roselle anthocyanins: antioxidant properties and stability to heat and ph. molecules, 23(6); 1357 yang, y., x. yuan, y. xu, and z. yu (2015). purication of anthocyanins from extracts of red raspberry using macroporous resin. international journal of food properties, 18(5); 1046–1058 © 2022 the authors. page 529 of 529 introduction experimental section materials methods physical and physico-chemical characterization of red banana fruit anthocyanin extraction identification of anthocyanin compounds total anthocyanins light influence test result and discussion physical and physico-chemical characterization of red banana fruit identification of anthocyanin compounds ftir test uv-vis test colour change test total anthocyanin content light effects conclusion acknowledgment research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 89-91 © 2017 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 18 august 2017; revised 5 september 2017; accepted 26 september 2017 http://doi.org/10.26554/sti.2017.2.4.89-91 removal lead (pb) and mercury (hg) from juaro fish (pangasius polyuranodon) using citric acid from pineapple extract (ananas comosus) as chelating agent pra dian mariadi1, rosnita sebayang1 1faculty of health science, musi charitas catholic university, palembang, indonesia corresponding author e-mail : pradian_dian@yahoo.co.id abstract an assessment of dietary risk of heavy metals exposure to human is important since it is the main of exposure. the aim of study to measure the contamination of lead and mercury in juaro fish meat and the effort to reduce contaminations using citric acid from pineapple extract as a chelating agent. samples was soaked and boiled in citric acid extract at concentration 50%, 75 %, 100 % for, 15 min, 30 min, 45 min at 25 oc, 50 oc and 100 oc. the concentration of lead and mercury in juaro fish lower than the maximum acceptable lever for pb and hg respectively (1 mg/kg for pb, 0.5 mg/kg for hg). the result indicated that after soaking and boiling in citric acid solution form pineapple extract at concentration 100 % for 45 min at 100 0c reducing heavy metals pb from 0.02 mg.kg-1 to 0.003 mg.kg-1 and hg from 0.011 mg.kg-1 to lower than 0.0001 mg.kg-1. the increasing of soaking time and boiling temperature, the levels of pb and hg in juaro fish tissue will decreasing. keywords: citric acid solution, pineapple extract, heavy metal 1. introduction heavy metals are the most important and basic pollutants because of their bioaccumulation and high toxicity even at very low dosage and cause serious dangers to ecological system as well as human health (tadjuradi, 2016). with the rapid growth of population and industrialization in the world, the frequency of accidently heavy metal pollution in soil, food and aquatic ecosystems boosted fast in recent years. due to its non-biodegradation and non decomposing characters. heavy metals ion can be accumulated through food chain and absorbed by human being. pollutions in the aquatic ecosystems has received much concern, due to the abundance, toxicity, persistence, ubiquity and non-degradability in the ecosystems and subsequent bio-accumulation of heavy metals (liu et al, 2016). heavy metals in polluted habitats may accumulate especially in fish tissue which in turn may enter into human food chain and eventually lead health risk (ahmed et al, 2015). eddy et al (2012) had reported the aquatic ecosystems in musi river contaminated by heavy metals such as lead and mercury. juaro fish (pangasius polyuranodon) is one of aquatic species which is thought to have high lead and mercury accumulations due to predatory fish. mercury is one the most hazardous heavy metal contaminants. the environment pollution by mercury originates from two source-natural and anthropogenic. coal burning, waste combustion, mining, sewage sludge, deposition, hg wood impreqnation and industrial practices are the main anthropogenic sources. (alloway, 1995). long term exposure to mercury compounds from food and water can lead to toxic effects on brain, cardiovascular, pulmonary, urinary, gastrointestinal and neurology system (kim et al, 2016; turaga et al, 2014). lead causes severe health risks such as fatigue, irritability, myalgia, coma, kidney, liver and brain damage, seizures encephalopathy nervous system dysfunction, disturbance of immune system and development of cancer (sander et al, 2009; goldstein et al, 1992). the technologies used for reduce contaminations in food using chelating agent. citric acid has potential as chelating agent to remove toxic metals (jiang et al, 2017; aderhold et al, 2017; shakour et al, 2014). pineapple (ananas comosus) is one of the fruits that have high concentrations of citric acid. citric acid includes a chelating agent which is a stabilizer at food processing. citric acid binds the heavy metals in the form of complex bond and can reduce side effects of heavy metals in food (hikmawati and lilis, 2016). interaction of citric acid with heavy metals can be enhanced by soaking (ulfa et al, 2014) and boiling process at high temperature (sari et al, 2014). the aim of the experimentations was to evaluate the metal mobilization induced by citric acid from pineapple extract when samples were soaking and boiled until 45 minute. 2. experimental section 2.1. experimental site the experiment was performed in food and beverage analysis laboratory, faculty of health science, musi charitas catholic university, mariadi et al. 2017 / science & technology indonesia 2 (4) 2017: 89-91 90 palembang, indonesia. the instrument was used a water-bath, hotplate magnetic stirrer and glassware instrument. 2.2. sample preparations juaro fish was purchased from traditional market in palembang, south sumatera, indonesia. samples of juaro fish was washed and separated their shells and meat. meat of juaro fish was soaked in a extract of citric acid at 50 %, 75 %, 100 % for 15 min, 30 min, 45 min at 25 oc, 50 oc, 100 oc. 2.3. heavy metals analysis the heavy metals such as pb and hg at juaro fish meat were analyzed by atomic absorption spectrophotometer (aas) shimadzu aa 7000 in industrial research and standardization laboratory palembang and absorption spectrophotometer (aas) shimadzu aa 2800 in environmental health and disease control laboratory palembang. sample (5 g) were dissolved in 25 ml h2so4(p), 20 ml hno3(p), 20 ml hno3-hclo4(1:1) then analyzed using aas. for mercury analysis, mercury vaporizer unit (hvu) was added to aas. 2.4. statistical analysis the normality value of multiple groups were analyzed by oneway analysis of variance (anova) with p < 0.05 was classified as statistically significant. 3. result and discussion 3.1. pb content in juaro fish (pangasius polyuranodon) heavy metals contamination has risen and become one of the most dangerous pollutants of environment pollution. continuously lead metal is released into the environment both naturally and human activities. the bioaccumulation of pb in food should be reduced by using chelating agent. citric acid as a chelating agent with vary concentration from pineapple extract, soaking time and boiled temperature was used to reduce the level pb in juaro fish. the level of pb studied were successfully reduced by citric acid and are presented in fig 1. the obtanined results from aas showed that pb content in juaro fish before soaking and boiled treatment was 0.02 mg.kg-1. the value shows that the pb levels in juaro fish under the permissible limit. based on indonesia national standard the permissible limits of pb content was 1 mg.kg-1. fish are considered as an important food source of macronutrients (carbohydrates, protein, fatty acids, vitamin and polyunsaturated fatty acids) and micro nutrients (copper, zinc, iron, selenium) for human health (arulkumar et al, 2017). bioaccumulation of lead and high toxicity even at very low dosage can cause serious dangers to human health (tajarudin et al, 2016). lead (pb) in juaro fish successfully remove above 80 % after soaked and boiled with 100 % pineapple extract for 45 min at 100 oc. citric acid was effective for the removal lead ions which is likely due to its c=c bond (jiang et al, 2017). removal effect of toxic metals among organic acids more effective at acidic condition. (pitsari et al, 2016) citric acid has large pka (pka = 3,15) provide anions to complex with metals (doors, 2005). the statistical analysis showed that each treatment was significantly different and suggest that the higher boiled temperature and longer period of treatment time at any concentration of citric acid can increase the removal of pb out from juaro fish. 3.2. hg content in juaro fish (pangasius polyuranodon) citric acid with varying concentration of pineapple extract, soaking time and boiling temperature was used to level of hg in juaro fish. the levels of hg studied were successfully reduced by citric acid presented in fig 2. the hg level in juaro fish from aas instrument before soaking dan boiling treatment was 0.011 mg.kg-1. the value shows that the hg levels in juaro fish under the permissible limit. although below the permissible limit, contamination of hg must be concern due to bioaccumulation, neurotoxicity and carcinogenicity (jomova, 2010). heavy metals especially mercury has contaminated aquatic system (malvandi, 2017), seafood species (morgano et al, 2013), croaker fish (musa et al, 2016), horseshoe crab (bakker et al, 2017) and fish (arulkumar et al, 2017). the mercury accumulated in body upon the consumption of contaminated fish. the adverse effect of hg are associated with development abnormalities children (parashor, 2013). mercury in juaro fish successfully removed above 80 % after soaked and boiled with 100 % pineapple extract for 45 min at 100 oc. the statistically analysis showed that each treatment was significantly different and suggest that higher boiled temperature and longer period of treatment at any concentration of citric acid can increase removal of hg out from juaro fish. it was indicates that an higher temperature related to increase the offered energy to separate the chemical bond of mercury metals in the materials and longer period of treatment time will give enough time for chelating agent to chelate with the heavy metals and extracted out from the juaro fish (azele et al, 2014; gzar et al,2014) 4. conclusion citric acid was able to chelate the lead and mercury metals in juaro fish. the increasing of boiled temperature and longer period of treatment at any concentration of citric acid from pineapple figure 1. reduction of lead (pb) in juaro fish 0 0,005 0,01 0,015 0,02 0 15 30 45 pb le ve l ( m g/ kg ) soaking time (min) 50oc, 50 % 100oc, 50% 25oc, 75 % 50oc, 75 % 100oc, 75 % 25oc,100% 50oc, 100 % 100oc, 100% 25oc, 50 % 0 0,0002 0,0004 0,0006 0,0008 0,001 0,0012 0 15 30 45 h g le ve l ( m g/ kg ) soaking time (min) 25oc, 50 % 50oc, 50 % 100oc, 50% 25oc, 75 % 50oc, 75 % 100oc, 75 % 100oc, 100% 0 0,005 0,01 0,015 0,02 0 15 30 45 p b le ve l ( m g /k g) soaking time (min) 50oc, 50 % 100oc, 50% 25oc, 75 % 50oc, 75 % 100oc, 75 % 25oc,100% 50oc, 100 % 100oc, 100% 25oc, 50 % 0 0,0002 0,0004 0,0006 0,0008 0,001 0,0012 0 15 30 45 h g le ve l ( m g/ k g) soaking time (min) 25oc, 50 % 50oc, 50 % 100oc, 50% 25oc, 75 % 50oc, 75 % 100oc, 75 % 100oc, 100% figure 2. reduction of hg in juaro fish mariadi et al. 2017 / science & technology indonesia 2 (4) 2017: 89-91 91 extract can increase of removal heavy metals (pb and hg) in juaro fish. the highest decreasing of pb and h level up to 80 % when samples were boiled in pineapple extract for 45 min at 100 oc. based on statistical data, the sig value of pb and hg 0.000 and 0.04, respectively. which showed the variation of pineapple exctract have an effect on the decrease of pb and hg. acknowledgement the authors are very thankful and appreciates to indonesian directorate general of higher education (dikti) for the financial support granted based on research of beginner lecturer. references aderholt, m: vogilien, d.l: kother, m., greipson, s. 2017. phytoextraction of contaminated urban soils by panicum virgantum l enhanced with applications of a plant growth regulator (bap) and citric acid. chemosphere 175(2017) 85-96. alloway, b.j.,1995. heavy metals in soils. balckie academic and professional. 4-15 ahmed, m.k., shaheen, n., islam, m.s., habibullahal-mamum m., islam, s., mohiduzaman, m., bhattacharjee, l., 2015. dietary intake of trace elements from highly consumed cultured fish (labeo rohita, pangasius and oreochromis mossambicus) and human health risk implications in bangladesh. chemosphere 128, 284-292. arulkumar, a., paramasivan, s., rajaram., r. 2017. toxic heavy metals in commercially important food fishes collected from palkbay southeast india. marine pollution bulletin 3. http:// dx.doi.org/10.106/j.marpolbul.2017.03.045 azelee, i.w., ismail, r., ali, r., bakat,w.a. 2014. chelation technique for the removals of heavy metals (as, pb, cd and ni) from green mussel (perna veridis). indian jurnal of geo-marine sciences 43(3). 372-376 bakker, a.k., dutton, j., sclafani, m., santangelo, n. 2017. accumulation of nonessential trace elements (ag, as, cd, cr, hg and pb) in atlantic horseshoe crab (limulus polyphemus) early life stages. science of total environment 596-597 (2017) 69-78. doors, s., 2005. organic acids. in: davidson, p.m., sofos, j.n., branen, a.l. 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e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper a simulation study on the simulated annealing algorithm in estimating the parameters of generalized gamma distribution amani idris a. sayed1,2* and sabri shamsul rijal muhammad1 1school of mathematical sciences, university sains malaysia, pulau pinang, 11800, malaysia 2department of mathematics, jazan university, jazan, 45142, saudi arabia *corresponding author e-mail: amani.sayed1983@yahoo.com abstract thisstudyproposedahybridcomputationalmodelbyincorporatingsimulatedannealingalgorithm(sa) inthemaximumlikelihood in estimation the parameters of generalized gamma distribution (ggd). the purpose is to improve the searching capacity of maximum likelihood estimator for generalized gamma distribution (ggd). a simulated annealing algorithm (sa) is one of the global search heuristics computational approach inspired by the metallurgical process, in which metal is rapidly heated to a high temperature, then cooled slowly until it reaches the lowest-energy state, increasing its strength and making it easier to work with. it has been applied in approximating global optimization in a large search space for various optimization problems. this study employs a simulated annealing algorithm (sa) to improve the global search capacity of maximum likelihood methods (mle) in estimating the parameters of the generalized gamma distribution (ggd). the generalized gamma distribution (ggd) constitutes an extensive family that contains nearly all of the most commonly used distributions including the exponential, weibull, and lognormal distribution. the performances of the proposed estimation method are computed based on their biases and mean square errors through a simulation study. the study reveals that the simulated annealing algorithm (sa) performs better than the classical estimators in estimating the parameters of generalized gamma distribution (ggd). keywords simulated annealing algorithm, generalized gamma distribution, parameters estimation methods, log-likelihood function. received: 28 october 2021, accepted: 08 january 2022 https://doi.org/10.26554/sti.2022.7.1.84-90 1. introduction the gamma distribution (gd) is one of the most important statistical distributions for its widely used in many �elds of data modelling and forecasting of various phenomena. it is useful in handling large scales of data due to its �exibility to be transformed to other distributions such as exponential and normal distributions. the important features of the generalized gamma distribution (ggd) made it useful in various areas of research which include business, engineering and other lifetime analysis (lawless, 2003; tang and cheong, 2004; eric et al., 2020). the probability density function of the gamma distribution is given as. fxk (x, u, \) = { 1 γ(u) [ 1 \ ]u xu−1e x \ , x > 0 0, otherwise (1) where a and q are the shape and scale parameters of the gamma distribution model respectively. we employ a generalized gamma distribution (ggd) in this work, which was established by amoroso (1925). the gamma distribution is among the most widely statistical distribution employed in modelling a di�erent kind of lifetime data set with application in modelling di�erent phenomena characterized with monotone failure rates. it requires a little measure of parameters for learning. the �rst generalization of the gamma distribution can be found in amoroso (1925), which analyzed and applied a ggd to �tting the income rates based on the ggd with four parameters has been studied by johnson et al. (1995). the study on the four gamma distribution was later reduced to the ggd according to stacy (1962) by setting the location parameter to zero. mudholkar and srivastava (1993) used the exponentiated method to derive the gamma distribution model for data anlysis. stacy (1962) developed the generalized version of the gamma distribution based three-parameters. agarwal and al-saleh (2001) modelled the distribution of hazard rates using the gamma distribution model. similar distribution was emplyed by balakrishnan and peng (2006) in creating a generalized version of gamma distribution to modelling frailty https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.84-90&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.84-90 sayed and muhammad science and technology indonesia, 7 (2022) 84-90 data. another sort of ggd suggested by nadarajah and gupta (2007) was used to �t drought data. another generalization of distribution by stacys used an exponentiated approach to ggd model and used it to lifetime and survival analysis (ortega et al., 2012). a study by chen et al. (2017) employed a generalized version of the gamma distribution (ggd) with three parameters in modelling the �ood frequency data analysis. zhao et al. (2018) employed the three-parameter ggd model in calculating the statistical characteristics of high-resolution sar pictures. similarly, mead et al. (2018) propose the modi�ed version of ggd to evaluate greater �exibility and appropriateess in representing data from a practical standpoint, and they derived a variety of identities and properties of this distribution, which include explicit representations for lifetime expression. researchers in the �elds of statistical distribution have tried a variety of methods in estimating the parameters of the ggd. this include, moment method (khodabina and ahmadabadib, 2010), quantile methods (nagatsuka and balakrishnan, 2012), modi�ed moment methods (dey et al., 2021), evolutionary algorithm (yonar and yapici, 2020), maximum likelihood (hirose, 1995), bayesian approach (khodabina and ahmadabadib, 2010; pradhan and kundu, 2011). however, because parameters involve leading to the same density function, it is di�cult and challenging face by researchers in estimating the parameters of the generalized version of the gamma distribution using methods like moment methods and maximum likelihood. the likelihood equations must be solved simultaneously in the maximum likelihood technique. to explore other approach in estimating the parameter of the generalized version of the gamma distribution, conventional methods were developed. it also showcases the incapability of the conventional/traditional method such as moment method and maximum likelihood estimator to estimate the parameters of the proposed ggd distribution. however, the results are unappealing due to their intricacy of the traditional method. as a result, it appears that estimating the parameters of the ggd is quite challenging and not straightforward. there is the need to incorporating other search approach such as heuristics method to overcome such challenges and limitation associated with the conventional methods. in this study, a stochastic computational methods based on the simulated annealing algorithm (sa) has been incorporated to reduce the complexity involve in the searching for the optimal parameters of the generalized version of the gamma distribution model. in this study, a simulation study has been carried out according to the proposed model. the remainder of this paper is organized as follows: the simulated annealing algorithm and generalize gamma distribution and its parameters have been presented in section 2. a simulated annealing algorithm for optimization of gamma distribution parameters is studied in section 3. the experimental results and with discussion have been presented in section 4. conclusions and recommendation the of the study in section 5. 2. simulated annealing algorithm the simulated annealing algorithm (sa) aims to generate new solutions using a random process through a series of probability distributions. this random operation does not necessarily improve the objective function, but even so, it may be accepted (franzin and stützle, 2019). the algorithm was originally used as an optimization process in metallurgical engineering to achieve the minimum energy by gradually reducing the atomic motion that reduces the uniformity of lattice defects, thereby reducing the metal temperature (du and swamy, 2016). the simulated annealing algorithm (sa) cannot be a�ected by any restraint at any local minimum and has an indulgent acceptance of any changes that arise in the objective function, thus its e�ciency makes it useful in many �elds, including �nance and the mathematical and statistical sciences (crama and schyns, 2003; orús et al., 2019; abubakar and sabri, 2021b; abubakar and sabri, 2021a). the acceptance probability in the sa algorithm can be written as, p = e −(δz) h (2) where δz denote the increase in the objective function and h represent the controlling parameter. some studies including (abbasi et al., 2006) and (bertsimas and tsitsiklis, 1993), presented the most general form of the simulated annealing algorithm (sa) which can be written in the following steps: i. start with initial solutions x=x0. ii. generate a random chance of the solutions x. iii. evaluate the objective function at the randomly generated solutions. iv. setting an initial controlling parameter h=h0 and an approach to reduce it as the process goes. the general form of the sa algorithm, which has been explained above, works toward minimizing the control parameter h, in adjusting the procedure which can be implemented in other problems. the purpose is to explore the feasibility of simulated annealing algorithm (sa) in estimating the parameters of proposed model in relation to conventional method. and to �nd out how the estimated parameters will maximize the log-likelihood function. to maximize the log-likelihood function, the controlling parameter h in the algorithm must be maximized too, so the objective function should be multiplied by (-1) according to (sabri and sarsour, 2019). the determination of the control parameter and generating initial and neighbouring solutions based on the sa procedure should be carefully observed. also, the data sample should be big enough to obtain an accurate result. the performance of the simulated annealing algorithm (sa) has been assessed according to mean absolute error (mae) based on the simulated data set for di�erent sample size. the e�ectiveness of mean absolute error (mae) has been demonstrated in several studies, including (peng and yao, 2003; franses, 2016; frías-paredes et al., 2018; sayed and sabri, 2022). the following section presents © 2022 the authors. page 85 of 90 sayed and muhammad science and technology indonesia, 7 (2022) 84-90 the generalised gamma distribution along with its parameters and statistical properties. 2.1 generalize gamma distribution and its parameters the most common pdf form of the generalized version of the gamma distribution (ggd) can be written as, f (t; u, v , c) = v γ(u)c ( t c )u v−1 e−( t c) u (3) where u>0 and v>0 are the shape parameters, c>0 is the scale parameter and γ(u) is the gamma function that de�nes as, γ(u) = ∞∫ 0 xu−1e−xdx (4) because such a distribution is associated with convergent di�culties of the mle, some reparameterization with the parameters was used to alleviate these di�culties as follow, ` = ln(c) + 1 v ln ( 1 _2 ) (5) f = 1 v √ u (6) _ = 1 √ u (7) where -∞< ` <∞, f > 0, 0 < _. based on this reparameterization and the values of the parameters, the ggd can include special cases of some distributions such as the gamma distribution (gd), the exponential distribution (ed), weibull distribution (wd), and the lognormal distribution (ld) as shown in figure 1. in this case, a continuous random variable xk taking a non-negative real value is said to follow the gamma distribution for k-years period. xk distributed using two parameters gamma distribution u and \ with mean=u\ and variance=u\2. then, k=2,...,4, we impose a new growth rate, w by letting xk=(1+w)k−1x1 . because the growth rate w is associated with the scale of the data, this results from the development of the gamma distribution to become a generalized gamma distribution as follows, fxk (x , u, (1+w) k−1 \) =  1 γ(u) [ 1 (1+w)k−1\ ]u xu−1e x (1+w)k−1\ , x > 0 0, otherwise (8) figure 1. generalized gamma distribution based on the di�erent parameters with the parameters u and (1 + w)k−1\ and having the mean=u(1+ w)k−1\ and variance=u [ (1+ w)k−1\ ]2 . estimating the parameters along with the growth parameter w of equation (8) using the method of the moment is not an easy task because it’s di�cult to construct the values of them from the mean and variance equations unless we �x the value of one of them and solve for the other two. from equation (8), the likelihood function (l) of xk is l(u, (1+ w)k1\ |xk) =− ln [γ(uk)] − uk ln((1+ w)k−1\k) + ln(xuk−1k ) − xk (1+ w)k−1\k (9) and, the log-likelihood function is then be simpli�ed as, l(u, (1+ w)k1\ |xk) =− k∗∑ k−1 ln [γ(uk)] − k∗∑ k=1 uk ln((1+ w)k−1\k) + k∗∑ k=1 ln(xuk−1 k ) − k∗∑ k−1 xk (1+ w)k−1\k (10) it is observed by various studies include (abbasi et al., 2006) and abubakar and sabri (2021b) that the maximum likelihood approach used to estimate the three parameters of our generalized gamma model is a di�cult process, this is because is hard to get a straightforward di�erentiation of the resulting log-likelihood function in equation (10). therefore, it is mathematically challenging in searching for the optimal parameters of the generalized gamma distribution simultaneously from equation (10) as di�erentiating the log-likelihood function towards u couldn’t be derived directly. therefore, it is easier to incorporate with another useful method such as the simulated annealing algorithm (sa) to search for the gamma distribution parameters, which works with the log-likelihood function as an objective function and aims to maximize it. the sa procedure © 2022 the authors. page 86 of 90 sayed and muhammad science and technology indonesia, 7 (2022) 84-90 use in estimating the parameters of the generalized gamma distribution has been presented in the following section. 3. simulated annealing algorithm for gamma parameters estimation in this work, a simulated annealing algorithm is used to estimate the parameters of the generalized gamma distribution and detect how close the estimated parameters are to the true ones. furthermore, we observe how the estimated parameters are going to maximize the log-likelihood function. this procedure involves some steps, as it is shown in figure 2. figure 2. block diagram of the proposed framework step1: variables designing start with generating the data sample randomly by simulation method using microsoft excel. from equation (1) the cumulative density function of x when k=1 is, fx1(x ∗) = x∗∫ 0 1 γ(u) ( 1 \ )u xu−1e− x \ dx = gamma(u, \ , x∗) (11) if the value of fx1(x ∗)=p, then we �nd x as, gamma(u, \ , x∗) = p → x∗ = gamma−1(u, \ , p) (12) in excel, the value of p is computed as the function of p=randa(). the cumulative density function of x when k>1 is, fxk (x ∗) = x∗∫ 0 1 γ(u) [ 1 (1+ w)k−1\ ]u xu−1e − x (1+w)k−1\ dx (13) and gamma(u, (1+ w)k−1\ , x∗) = p (14) thus, x∗ = gamma−1(u, (1+ w)k−1\ , p) (15) so, in microsoft excel x∗ is generated and distributed using cdf of the gamma distribution to calculate the log-likelihood function in the following few steps: 1. generate p using the function =rand(). 2. select initial values for u, \ , w. 3. generate x∗ using the inverse gamma function gamma−1 (u,(1+ w)k−1\ , p). 4. find the cumulative gamma distribution fx1(x ∗) using the initial parameters. 5. find the inverse log of fx1(x ∗) and calculate the loglikelihood function. 6. estimate a set of 100 gamma parameters of u, \ , w using the simulated annealing method. 7. find the cumulative gamma distribution fx1(x ∗) using the mean of the 100 estimated parameters. 8. find the inverse log of fx1(x ∗) and calculate the loglikelihood function. step 2: simulated annealing optimization as mentioned earlier, it is only helpful to incorporate a useful method such as simulated annealing to estimate gamma parameters that maximize the log-likelihood function. the process of sa requires advanced programming, hence, in this study, matlab coding is used to estimate 100 values of the gamma parameters. the sa algorithm is explained as follows: 1. get a big enough sample of data x∗. 2. determine the objective function f = (l, x∗) where l is the maximum likelihood. 3. select controlling parameters for the sa, for example, ho, h, a, b such that: while h > ho, h = ah. 4. select lower and upper bounds of random variables lb = [., ., .] , ub = [., ., .]. 5. generate random values a, b, and c within the lower and upper bounds. 6. compute the likelihood function l at random values. 7. generate neighbour values a1, b1, and c1 within the lower and upper bounds. 8. compute the likelihood function l1 at the neighbour values. 9. if l1 > l, then l1 = l, and a = a1, b = b1, c = c1. 10. else generate a random value rn(0,1). 11. if e− (l1−l) h >r then a = a1, b = b1, c = c1. 12. print 100 sets of a, b, and c which are û,\̂, and ŵ respectively. 4. experiment result and discussion in this study, 4 sets with di�erent samples sizes of 50, 100, 200, and 500 were generated using microsoft excel for the values of k=2,3,4,5 accordingly. the cdf of the gamma distribution with three initial parameters (u=4, \=0.3, w=-0.05) was distributed across all data sets generated. then the sa algorithm was used to further estimate 100 sets of the gamma parameters for each data sample size. the performance of the © 2022 the authors. page 87 of 90 sayed and muhammad science and technology indonesia, 7 (2022) 84-90 sa algorithm was evaluated using the mean absolute error (mae) of the estimated parameters û,\̂, and ŵ for each sample size as follows, 1 3 ( |û − u | + |\̂ − \ | + |ŵ − w | ) (16) the cdf of gamma distribution was calculated for each sample size with the initial parameters and the mean of the estimated parameters to see how close the distributions will be for the di�erent data sets. finally, the inverse of the maximum likelihood is calculated based on the initial parameters, then the average of the estimated parameters for each sample size to observe on how the means of our estimated parameters sets will maximize the maximum likelihood. figure 3. box plots of the mae for each sample size sample 50, 100, 200 and 500 figure 4. cdf of the ggd for 50 sample sizes table 1. estimated parameters of the ggd via sa sample size (n) mean of the estimate likelihood at the initial estimate likelihood at the mean 500 4, 0.31, -0.052 504.7 524.27 200 4.2, 0.29, -0.051 194.03 202.09 100 4.2, 0.27, -0.052 93.25 125.57 50 4.1, 0.33, -0.051 45.65 55.79 according to box plots in figure 3, the larger the sample size, the closer the average absolute error of the estimated parameters to zero. the sample of size 50 has a larger spread figure 5. cdf of the ggd for 100 sample sizes figure 6. cdf of the ggd for 200 sample sizes while the spread of the data gets smaller when the size of the data sample gets larger, which means that the 100 sets of estimated parameters û, \̂, and ŵ fall closer to the initial parameters the larger the data sample gets, which stresses the e�ciency of the algorithm. figures 4 to 7, displayed the cdf of the ggd function based on the data set generated using both the initial parameters and the mean of the estimated parameters for each sample size. it can be observed that the estimated parameters of the generalized gamma distribution are getting closer to the true parameters as the sample size increases. table 1 reports the mean of the estimate, the likelihood value of the mean and the initial estimate. it is seen that the gamma accuracy of the estimated parameters is getting closer to the true parameters when the sample size becomes large. moreover, the figure 7. cdf of the ggd for 500 sample sizes © 2022 the authors. page 88 of 90 sayed and muhammad science and technology indonesia, 7 (2022) 84-90 mean estimated parameters using the sa algorithm maximize the likelihood function optimally. when it comes to parameter estimation for a generalized gamma distribution (ggd), the classical method produces a lot of inaccuracies. although the amount of inaccuracies in sa is low, the o�ered settings are occasionally surprising and unrealistic. this reveals that the simulated annealing algorithm can work optimally with maximum likelihood in estimating the parameters of the generalized gamma distribution model. 5. conclusion the goal of this study was to explore a simple approach to �t a generalized gamma distribution (ggd) using simulated data, not to propose a new theoretical estimation of the parameters of the generalized gamma distribution. this study shows the e�ciency of using the simulated annealing algorithm based on to estimate the parameters of the generalized gamma distribution for a randomly generated data sample based on the simulation method explained above. the results presented in the tables and �gures demonstrated that the parameters of generalized gamma distribution can be optimally estimated using a simulated annealing algorithm incorporated in the maximum likelihood method and the ability to simplify the use of such a generalized distribution to model important phenomena that other distributions cannot. implementing the simulated annealing algorithm on other distributions from the same family will be our future direction. the study presented in this paper can also contribute to modelling di�erent real-life data set such as internal rate of return and option pricing in the �nancial market, wind speed and reliability problems in reliability engineering. 6. acknowledgement i would like to thank jazan university, saudi arabia for sponsorship opportunity given to me to pursue phd at the universiti sains malaysia. i am thankful to my family for their uncounted support and encouraged during my study period. also, i would like to thank my supervisor who gave me a lot of support and suggestions, and i would 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(1962). a generalization of the gamma distribution. the annals of mathematical statistics, 33(3); 1187–1192 tang, l. c. and w. t. cheong (2004). cumulative conformance count chart with sequentially updated parameters. institute of industrial engineers transactions, 36(9); 841–853 yonar, a. ş. and n. p. yapici (2020). a novel di�erential evolution algorithm approach for estimating the parameters of gamma distribution: an application to the failure stresses of single carbon fibres. hacettepe journal of mathematics and statistics; 1–22 zhao, w., j. li, x. yang, q. peng, and j. wang (2018). innovative cfar detector with e�ective parameter estimation method for generalised gamma distribution and iterative sliding window strategy. iet image processing, 12(1); 60– 69 © 2022 the authors. page 90 of 90 introduction simulated annealing algorithm generalize gamma distribution and its parameters simulated annealing algorithm for gamma parameters estimation experiment result and discussion conclusion acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper the effects of reactive oxygen and nitrogen species (rons) produced by surface dielectric barrier discharge (sdbd) non-thermal plasma with treatment time and distance variations to kill escherichia coli renaldo apriandi kasa1*, unggul pundjung juswono2, dionysius j. d. h. santjojo2 1master of physics study program, universitas brawijaya, malang, 65145, indonesia2departement of physic, universitas brawijaya, malang, 65145, indonesia *corresponding author: randi−kasa@student.ub.ac.id abstractresearch on the inactivation of escherichiacoli causing diarrheal disease using non-thermal plasma sdbd has been carried out. sdbdis a new technique for non-thermal plasma generation with several advantages: low power generation, comprehensive treatmentarea coverage, and reducing the potential effects of burning and drying tissue. this study aimed to analyze the effect of treatmenttime variations, namely 0 as control, 60, 75, 90, 105, and 120 seconds and treatment distance variations of 3, 6, 9, 12, and 15 mmof non-thermal plasma treatment of sdbd on e. coli. the results of the non-thermal plasma sdbd treatment with variations intime and distance showed that the longer the treatment time, the more bacterial cells died. colony counts decreased to 4.33 x 107cfu/ml compared to the control, 409 x 107 cfu/ml, with a treatment time variation of 120 seconds, yielding the best treatmentresults. at the same time, the results of the treatment for variations in the non-thermal plasma distance of sdbd showed that thesmaller the treatment distance, the greater the bacterial death rate, with the best treatment results at a 3 mm treatment interval,with colony counts of 8 x 107 cfu/ml, compared to 409 x 107 cfu/ml in control. based on these results, sdbd non-thermalplasma treatment can be used to inactivate or kill bacteria with effectiveness in killing bacteria depending on the length of treatmenttime and the distance of treatment. keywordsnon-thermal plasma, sdbd, e. coli, rons, treatment time, treatment distance received: 18 september 2022, accepted: 13 desember 2022 https://doi.org/10.26554/sti.2023.8.1.45-51 1. introduction infectious diseases are one of signicant health problems in almost all developing countries, including indonesia. one of the most common infectious diseases is diarrhea. according to ragil and dyah (2017), diarrhea is one of the leading causes of illness and death in almost all geographic areas, and all age groups can be aected. in indonesia, diarrheal disease is a potential endemic disease of extraordinary events (klb), and it is frequently fatal. according to kemenkes ri (2018), the number of suerers of diarrheal disease based on the results of the diagnosis by health workers was 6.8%, while based on the symptoms experienced, 8%. the number of patients with diarrheal diseases classied according to age found that the age group of 1 to 4 years had the highest number of suerers, namely 11.5%. in addition, the age group of 75 years and over has a relatively high number of suerers, namely 7.2% (prabhakara, 2010). microorganisms that generally cause disease are called pathogens. pathogens include bacteria, protozoa, viruses, prions, fungi, and worms. these pathogens can cause various symptoms and diseases, including diarrhea (levy et al., 2018). pathogens that cause diarrheal disease can come from viruses, for example, rotavirus (40-60%), escherichia coli (2030%), shigella sp. (1-2%), and the parasite entamoeba histolytica (ragil and dyah, 2017). several conventional sterilization techniques have been developed to inactivate disease-causing microorganisms, such as sterilization using dry heat (oven), moist heat (autoclaving), and chemicals such as glutaraldehyde and the use of gamma irradiation (moisan et al., 2001; morent and de geyter, 2011; park et al., 2003). this conventional technique that has been used has several disadvantages, such as high processing temperatures, long sterilization times, and the use of toxic chemicals, resulting in changes to the material during sterilization, and this technique is quite expensive to use (moisan et al., 2001; morent and de geyter, 2011). based on the limitations of conventional methods, it is necessary to have a new and alternative https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.45-51&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.45-51 kasa et. al. science and technology indonesia, 8 (2023) 45-51 sterilization method, namely pretreatment with non-thermal plasma (plasma sterilization) (hati et al., 2012). plasma is the fourth matter after solids, liquids, and gases. plasma is dened as an ionized gas of free particles (putra et al., 2021; scholtz et al., 2021; šimončicová et al., 2019). based on the temperature, plasma is divided into thermal plasma and non-thermal plasma (morent and de geyter, 2011). cold or non-thermal plasma is produced by applying an electric or electromagnetic eld to a gas. plasma contains excited states of molecules and atoms, cations and anions, free radicals, electrons, uv radiation, ozone, superoxide, hydroxyl radicals, singleoxygen, atomicoxygen, nitrogenoxides, ornitrogen dioxide (puligundla and mok, 2017; zheng et al., 2016). these species exhibit antimicrobial activity against various microorganisms, including bacteria, yeasts, and even bacterial and fungal spores (lópez et al., 2019). surface dielectric barrier discharge is a new technique for non-thermal plasma generation with several advantages: low powergeneration, comprehensive treatment area coverage, and reducing the potential eects of burning and drying tissue. several non-thermal plasma sterilization techniques have been carried out, but further research is needed to optimize nonthermal plasma techniques. therefore, this study aimed to analyze the eect of treatment time and distance of non-thermal sdbd plasma treatment on e. coli. 2. experimental section 2.1 materials the non-thermal plasma system used in this study is a surface dielectric barrier discharge. the non-thermal plasma of the surface dielectric barrier discharge is generated using a 20 v dc voltage source which is then transformed into a high voltage source to create the plasma. the scheme used in this study is shown in figure 1. the plasma non-thermal discharge surface dielectric barrier uses two copper electrodes. a dielectric separates two copper electrodes. the two electrodes are connected to a voltage source, with one electrode connected to the ground and the other connected to a high-voltage source. the sample used in this study was e. coli obtained from the microbiology laboratory, faculty of medicine, brawijaya university. in addition, some materials, namelynutrient agar (na), are used as media for bacterial growth and sterile physiological nacl for dilution. 2.2 methods 2.2.1 e. coli sample preparation and sdbd non-thermal plasma treatment e. coli isolates that had been incubated for 24 hours were diluted with serial dilutions up to 10−6 with one loop of bacterial isolates homogenized with 9 ml of sterile physiological nacl (10−1 dilution).1 ml of the 10−1 dilution of bacterial suspension was homogenized with 9 ml of sterile physiological nacl (10−2 dilution). this step was carried out until a dilution of 10−6. the results of the dilution were then treated using nonthermal plasma with the surface dielectric barrier discharge figure 1. schematic of sdbd non-thermal plasma with variations in treatment time (0 as control, 60, 75, 90, 105, 120 seconds) and treatment distance (3 mm, 6 mm, 9 mm, 12 mm, 15 mm). the results of the treatment were then spidered using a triangular rod. after that, it was incubated at 37°c for 24 hours by placing the petri dish in an inverted position. the next step was to count the number of colonies in each treatment. each experiment was repeated three times. 2.2.2 optical emission spectroscopy optical emission spectroscopy (oes) was used to characterize reactive plasma species and to analyze plasma composition, which can explain the relationship or mechanism between reactive spaces formed in plasma and the ability to inactivate bacteria (wiegand et al., 2014). the optical emission spectrum was measured using aurora 4000 at a wavelength of 200 to 900 nm with an integration time of 5000 ms and 3 repetitions of the spectrum capture and then averaged to obtain the optical emission spectrum from the plasma. the emission spectrumobtainedwas thenanalyzedqualitativelytodetermine the chemical species at each wavelength peak. the results of identifying the wavelength peaks were then analyzed using the national institute of standards and technology atomic spectrum database and previous journal publications to identify chemically active species (sarangapani et al., 2016). 2.2.3 data analysis the data obtained were based on the eect of treatment time (0, 60, 75, 90, 105, 120 seconds) and treatment distance (3, 6, 9, 12, 15 mm) on the number of bacteria, tabulated and analyzed using anova using spss software. 26. if p-value < 0.05 h0 was accepted, then the length of treatment time and treatment distance aect the number of bacteria. 3. result and discussion 3.1 optical emission spectroscopy of sdbd non-thermal plasma an optical emission spectrum (oes) can measure and analyze reactive species produced by non-thermal plasma. the spectrum results obtained can be analyzed for reactive species by looking at the spectrum peaks. in the following section, fig© 2023 the authors. page 46 of 51 kasa et. al. science and technology indonesia, 8 (2023) 45-51 figure 2. oes spectrum of sdbd non-thermal plasma with treatment time variation and treatment distance variation ure 2 depicts the spectrum obtained from a surface discharge dielectric barrier non-thermal plasma. spectrum results were obtained using oes for each variation of treatment time and distance. the time variation is taken every 60 seconds, 90 seconds, and 120 seconds, while the distance variation is taken every 3 mm. 6mm, and 9mm. the spectrum results with time variations show the increasing intensity with longer treatment time. in contrast, for variations in the distance, the intensity will be smaller if the distance from the plasma source is further away. the resulting spectrum was measured using oes at a wavelength of 200 to 900 nm from the plasma source. the intensity emitted from the plasma source is recorded at each wavelength. in the formation of plasma, various chemical species are in an excited state. the chemical species produced in the gas phase were observed using oes during plasma release (sarangapani et al., 2016). in the uv region, the emission spectrum shows that n2 and n2+ excitation species’ emission shows dierent peaks. a small peaks of oh appear at wavelengths 296,1 nm (adhikari et al., 2021; dhungana et al., 2020; hosseini et al., 2018; naz et al., 2021; sarangapani et al., 2016). the low intensity of singlet oxygen is at a wavelength of 777.5 nm (sarangapani et al., 2016). at the same time, the n2 second positive system (sps) has a prominent peak at a wavelength of 313-390 nm, n2 rst negative system (fns) at a wavelength of 390-450 nm (akter et al., 2020; misra et al., 2015). from the reactive species produced in the gas phase plasma, long-lived or short-lived reactive species such as hydrogen peroxide (h2o2) and ozone (o3) are formed as long-lived reactive species, and short-lived reactive species such as hydroxyl radicals (•oh), singlet oxygen (1o2), superoxide anion (o2−), atomic oxygen (o), nitrite oxide (no), and peroxynitrite (onoo−), all of these reactive species exhibit antimicrobial activity (xu et al., 2018). 3.2 eect of treatment time and distance of sbdb nonthermal plasma teatment on the number of colonies non-thermal plasma can decontaminate bacteria. the mechanism and level of decontamination capability vary depending on the length of treatment time, the distance of treatment, the amount of voltage used, and the source of the gas used. all play a role in how eective non-thermal plasma is at decontaminating bacteria (amalda et al., 2020). in research on bacterial inactivation using sdbd non-thermal plasma treatment, variations in treatment time and treatment distances were used. for the treatment time, variations in treatment time were used, namely 60 s, 75 s, 90 s, 105 s, and 120 s. various treatment distances were also used, namely 3 mm, 6 mm, 9 mm, 12 mm, and 15 mm. from the results of the treatment obtained, it can be seen in table 1 and table 2 that non-thermal plasma inuences bacterial inactivation for variations in treatment time and variations in treatment distance. the longer the treatment time, the more bacteria are inactivated, or the number of inactivated bacteria is directly proportional to the length of treatment time. the eect of treatment time on colony number can be seen in figure 3. meanwhile, treatment results with distance variations and sbdb non-thermal plasma still aect the inactivation of bacteria. the smaller the distance of treatment used for treatment, the more bacteria will die, or the ability of the bacteria to live will be smaller. the eect of treatment distance on the number of colonies can be seen in figure 5. the results of the treatment showed that the treatment time of 120 seconds had a better ability to inactivate or kill bacteria than other treatments. the number of bacteria that grewafterbeing treated for120 seconds was an average of 4.3 x 107 cfu/ml. this number was much lower than the number of bacteria that grew without non-thermal plasma treatment, whichwas409x107 cfu/ml.while fortheshorter treatment time, the number of colonies that grew more and more was 105 s, 90 s, 75s, and 60 s, with the average number of colonies growing was 11 x 107 cfu/ml, 13 x 107 cfu/ml, 46.33 x 107 cfu/ml, 56 x 107 cfu/ml. pictures of the number of colonies before (control) and after treatment with treatment time variations can be seen in figure 4. meanwhile, from the results of the variation in treatment distance, 3 mm has a more extraordinary ability to inactivate bacteria than other treatment distances. the number of bacteria that grew after being treated at 3 mm averaged 8 x 107 cfu/ml. this number is much decreased compared to the number of bacteria that grow when the treatment is carried out at a longer distance. at the furthest distance carried out in this study, which was 15 mm, the number of colonies growing on average was 253 x 107 cfu/ml. at the same time, the number of bacterial colonies in the control treatment was 409 x 107 cfu/ml. images of colony count before (control) and after treatment with treatment distance variations can be seen in figure 6. © 2023 the authors. page 47 of 51 kasa et. al. science and technology indonesia, 8 (2023) 45-51 table 1. number of colonies before (control) and after the treatment with treatment time variations (p < 0.05) time (second) distance (mm) number of colonies (x 107 cfu/ml) treatment i treatment ii treatment iii control 410 418 399 60 3 54 46 68 75 3 60 43 36 90 3 13 15 11 105 3 7 3 23 120 3 4 3 6 figure 3. graph of the number of colonies before (control) and after treatment with treatment time variations (60 s, 75 s, 90 s, 105 s, 120 s) (r2 = 0.98188) the treatment of time variation and distance variation shows that there is an eect of non-thermal plasma treatment of sdbd. this eect is due to the reactive species formed during plasma generation. the rons formed to have an important role in the inactivation of bacteria. rons can disrupt the bonding of microbial cell structures with lipid peroxidation, damaging the rons membrane as reactive free radicals (no, •oh, and superoxide) or strong oxidizing agents (h2o2 and o3) can penetrate microorganisms. furtherchemical reactions can occur in the cytoplasm that can oxidize cellular proteins or microbial dna (klämp et al., 2012). one of the molecules that are the main agent of bacterial inactivation is no (nitrogen oxide). no can destroy cells by dimerizing thymine bases on dna strands, disrupting dna replication (amalda et al., 2020; tian et al., 2010). besides no, the reactive species formed during plasma formation is h2o2 which has the potential to cause oxidative damage. besidesbeingable tocauseoxidativedamage,h2o2 alsofunctions as a more potent hydroxyl radical (•oh) precursor. the •oh radical is a reactive oxygen species with excellent reactive abilfigure 4. picture of the number of colonies before (control) and after treatment with treatment time variations © 2023 the authors. page 48 of 51 kasa et. al. science and technology indonesia, 8 (2023) 45-51 table 2. number of colonies before (control) and after the treatment with treatment distance variations (p < 0.05) time (second) distance (mm) number of colonies (x 107 cfu/ml) treatment i treatment ii treatment iii control 410 418 399 120 3 10 6 8 120 6 12 13 14 120 9 49 70 85 120 12 137 109 224 120 15 284 242 233 figure 5. graph of the number of colonies before (control) and after treatment with treatment distance variations (3 mm, 6 mm, 9 mm, 12 mm, 15 mm) (r2 = 0.99727) ity and can produce oxidative damage to cell components (pai etal.,2018). the•ohradical is a strongoxidant thatcancause a decrease in atp, thereby causing low energy in cells. the •oh radical can also break the phosphodiester bond of dna molecules, which causes dna fragmentation, and can become lipids in cell membranes, resulting in cells being unable to replicate or causing cell death (feng and wang, 2020). in addition, another strong oxidizing agent plays a role in the inactivation of bacteria, namely ozone (o3). ozone has a considerable oxidation potential, which can damage cell walls and bacterial cytoplasmic membranes, increasing membrane permeability. as a result, there is a decrease in surface tension which results in cell leakage. furthermore, ozone and other reactive species easily enter the cell and damage bacterial nucleic acids, damaging the pyramidal rings and breaking the bonds between the pyramidal rings and the sugar groups in nucleic acids. this nucleic acid damage will result in cell death (kristanti and dessy, 2012). the concentration of reactive species formed during nonthermal plasma treatment signicantly aects the sterilization figure 6. picture of the number of colonies before (control) and after treatment with treatment distance variations © 2023 the authors. page 49 of 51 kasa et. al. science and technology indonesia, 8 (2023) 45-51 ecacy. the longer the treatment time, the more reactive the plasma species contains and the more eective it is in killing bacteria. similarly, the variation in treatment distance showed a relationship between the ability of bacteria to survive and the number of reactive species produced during plasma treatment. the results of the oes spectrum in figure 3. show that the farther the treatment distance, the smaller the intensity of the spectrum, which indicates that the fewer reactive species formed, the lower the ability to kill bacteria. 4. conclusion the results of research that have been carried out on the eect of rons produced by sdbd non-thermal plasma to kill escherichia coli show that the time and distance of treatment aect the numberof colonies that live before and after treatment. for variations in treatment time, the longer the treatment time, the more bacteria are inactivated, or the more bacteria die where the numberof colonies that growwhen treated with a treatment time of 120 s, which is 4.3 x 107 cfu/ml, is much lower than the control, which is 409 x 107 cfu/ml. as for variations in treatment distance, the farther the treatment distance, the more the number of colonies that live, where the number of colonies that grow when treated with 15 mm, namely 253 x 107 cfu/ml, signicantly decreased when treated with 3 mm, namely 8 x 107 cfu/ml. based on these results, further research can be investigated more deeply by looking at the eect of non-thermal plasma treatment on dna, lipids, proteins, and bacterial cell morphology to determine the mechanism of non-thermal plasma treatment that kills bacteria. additionally, several variations of parameters, such as gas source and voltage, can be carried out in order to obtain the most eective non-thermal plasma composition. 5. acknowledgment the author would like to thank lembaga pengelola dana pendidikan (lpdp), which has funded this research, and all parties who 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2667–2672 © 2023 the authors. page 51 of 51 introduction experimental section materials methods e. coli sample preparation and sdbd non-thermal plasma treatment optical emission spectroscopy data analysis result and discussion optical emission spectroscopy of sdbd non-thermal plasma effect of treatment time and distance of sbdb non-thermal plasma teatment on the number of colonies conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper synthesis, characterization of chitosan-zno/cuo nanoparticles film, and its effect as an antibacterial agent of escherichia coli ahmad fatoni1*, agnes rendowati1, lasmaryna sirumapea1, lidya miranti1, siti masitoh2, nurlisa hidayati3 1bhakti pertiwi high school of pharmacy science, palembang, south sumatera, 30128, indonesia2undergraduate school of bhakti pertiwi high school of pharmacy science, palembang, south sumatera, 30128, indonesia3department of chemistry, faculty of mathematic and natural sciences, sriwijaya university, indralaya, ogan ilir, south sumatera, 30862, indonesia *corresponding author: ahfatoni@yahoo.com abstractthe film of chitosanzno/cuo nanoparticles was synthesized. this study were the synthesis and characterization of the chitosan-zno/cuo nanoparticles film and its effect as an antibacterial of escherichia coli. the zno, cuo, and zno/cuo were biosynthesized bybiological method and for the synthesis of the chitosan-zno/cuo nanoparticles film, the casting method was adopted. the productwas analyzed by ftir spectroscopy, x-ray diffraction (xrd), and scanning electron microscope (sem), respectively. the product ofchitosan-zno/cuo nanoparticles film as paper disk and agar disk diffusion method was selected to study an antibacterial agent ofthis product. the zn-o or cu-o group was observed at a peak between 468-675 cm−1 for zno and 503 and 619 cm−1 for cuonanoparticles, respectively. zno, cuo, and zno/cuo nanoparticles are in the crystalline form and it has a crystallite size of 13.21, 13.21,and 11.49 nm respectively. after interacting with chitosan, the metal nanoparticles such as zno, cuo, and zno/cuo nanoparticlescan change the crystalline form of chitosan to be amorphous form. the addition of zno, cuo, and zno/cuo nanoparticles in thechitosan will change the surface morphology of chitosan. chitosan-zno/cuo nanoparticles film can inhibit the growth of escherichia coli bacteria. keywordschitosan-zno/cuo nanoparticles film, characterization, escherichia coli received: 31 october 2022, accepted: 30 may 2023 https://doi.org/10.26554/sti.2023.8.3.373-381 1. introduction the method for synthesis of zno/cuo can be done by chemical (das and srivastava, 2017; goyal et al., 2021; shinde et al., 2022; saravanakkumar et al., 2018; alzahrani, 2018; jayaramudu et al., 2019) and not chemical method such as a biological method (fouda et al., 2020; adeyemi et al., 2022; cao et al., 2021). the major synthesis of metal nanoparticles is divided into three methods: physical, chemical, and biological methods (naveed ul haq et al., 2017) . metal nanoparticles such as cuo and zno nanoparticles can be synthesized by chemical (asamoah et al., 2020) , biological (mohamed, 2020; jan et al., 2021), and physical methods (gondal et al., 2013; al-dahash et al., 2018). bloch et al. (2021) reported that the advantages of the synthesis of metal nanoparticles by the physical, chemical, and biological methods are that toxic chemicals are not used, high product, and easy, respectively. but the disadvantages are the expensive instrumentation, toxic chemicals, and difficulty to control the size of metal nanoparticles in the synthesis of metal nanoparticles by physical, chemical, and biological methods, respectively. on other hand, the researchers have chosen a biological method than a physical and chemical method. a cheap method is a base in the synthesis of metal nanoparticles by biological method (pantidos and horsfall, 2014) . the effect of ph, the concentration of reactant, reaction time, and temperature are a challenge in this method (zhang et al., 2020) . the researchers made a combination between metal oxide nanoparticles 1 and metal oxide nanoparticles 2 such as zno and cuo nanoparticles. this combination aims to increase sensitive biosensors (solanki et al., 2011; goyal et al., 2021), antibacterial (saravanakkumar et al., 2018) , photocatalysts (fouda et al., 2020) , and cytotoxicity properties (cao et al., 2021) . chitosan can be formed in film form. the flexibility of chitosan film is an advantage of chitosan film (estevam et al., 2012) but in the film form, chitosan can’t inhibit the growth of bacterial (foster and butt, 2011) .to increase the character of chitosan film, the researchers are using inorganic metal oxide (zno nanoparticles) to form chitosan-zno nanocomhttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.373-381&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.373-381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 posite film as an antibacterial agent (rahman et al., 2018) and zno/cuo nanoparticles to form chitosan-zno/cuo nanoparticles film for photodegradation and solar irradiation (alzahrani, 2018) . in this study, the first, the zno, cuo, and zno/cuo nanoparticles were biosynthesized by biological method and it is different from previous literature (alzahrani, 2018; jayaramudu et al., 2019). the second, the zno, cuo, and zno/cuo nanoparticles are used as modifier agents for chitosan respectively and all of the products are in the film form. all films are prepared by casting method. the characterization of this film with fourier transforms infrared spectroscopy (ftir), scanning electron microscopy (sem), and x-ray diffraction (xrd). application of all the films is as antibacterial of escherichia coli with the agar diffusion method. 2. experimental section 2.1 materials and instruments chitosan with dd 87% (cv. ocean fresh bandung, west java, indonesia). zinc acetate pentahydrate (merck), copper sulphate pentahydrate (merck), sodium hydroxide (merck), nutrient agar (merck), and acetic acid glacial (merck). we use microorganisms (escherichia coli) from our laboratory, including aquadest. guava seed (psidium guajava l.) leaves from palembang. ftir spectrophotometer (shimadzu prestige-21), scanning electron microscopy ( jeol jsm 6510 la), x-ray diffraction (shimadzu xrd 6000) and uv-vis spectroscopy (genesys 150 thermo scientific). 2.2 ethanolic extract as medium in biosynthesis this medium was prepared by maceration process and followed the procedure from fatimah et al. (2016) with slight modification. a dry leaf guava seed (25 g) was soaked in ethanol 70% (v/v, 250 ml) in a maceration bottle (24 h). after 24 h, the filtrate was separated and collected in a clean bottle and stored a room temperature for the further experiment (filtrate i). the residue was macerated again with 250 ml ethanol 70% (v/v) (24 h). the mixture was filtered, and the filtrate was collected and merged with filtrate i. all filtrate was stored at a room temperature. 2.3 biosynthesis of metal oxide nanoparticles the procedure of biosynthesis was adopted from fouda et al. (2020) with slight modification. the ethanolic extract of guava seed leaves (75 ml) in a beaker glass 250 ml was added by the solution of zinc acetate dihydrate (0.2743 g, 25 ml) and the concentration of zinc acetate pentahydrate was 0.0124 m. this beaker glass was heated on a hot plate at 80°c for 60 minutes with continuous stirring. the 0.1 m of sodium hydroxide solution (10 ml) was added to this beaker glass with continuous stirring (ph 10). the mixture was stored for one night until the precipitation appeared. the filtrate and residue (zno nanoparticles) were separated, and zno nanoparticles were washed with aquadest (15 ml) and absolute ethanol (15 ml). the product of zno nanoparticles was dried in the oven (60°c) until dry. the same procedure was used to biosynthesis of cuo and zno/cuo nanoparticles as seen in table 1. 2.4 synthesis of the film the synthesis of film a was adopted from kalia et al. (2021) with slight modification. chitosan solution in 250 ml of beaker glass (0.1 g of chitosan powder and10 ml of acetic acid solution 1% v/v) was added 0.1 g of zno nanoparticles and shaken by continuously stirring (room temperature, 1 h). a polypropylene petri dish with a diameter of 7.4 cm was filled with the chitosan and zno nanoparticle solution and left to dry at room temperature. figure 1 depicts the synthesis’s organizational design. the same procedure was used to prepare the films b, c, d, and e, which are listed in table 2. figure 1. synthesis chitosan-metal oxide nanoparticles film 2.5 characterization zno, cuo and zno/cuo nanoparticles were analyzed by uv-vis spectrometer to obtain their uv-vis spectra. the wavelengths ranging from 200 to 550 nm were used to this analysis. zno, cuo, zno/cuo nanoparticles, and film ae were characterized by their functional groups with ftir spectrophotometer (the region between 4500 and 500 cm−1). x-ray diffraction is used for physical structure analysis of zno, cuo, and zno/cuo nanoparticles, film a-e, and calculating the crystallite size of zno, cuo, and zno/cuo nanoparticles. the xrd operational conditions refer to previous literature (fatoni et al., 2021) . the surface morphology of chitosan film, films a, b, and d was characterized by sem at 15 kv with various magnifications x 3500 (scale bars = 5 `m) and × 10000 (scale bars = 5 `m). 2.6 the antibacterial procedure of the film chitosan-metal oxide nanoparticles three petri plates were used in this study. the agar disc diffusion method was used for the identification of chitosan-metal © 2023 the authors. page 374 of 381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 table 1. the materials in the biosynthesis of metal oxide nanoparticles the ethanolic extract of guava seed leaves (ml) zinc acetate pentahydrate (g) copper sulphate pentahydrate (g) aquadest (ml) sodium hydroxide solution (m, ml) the name of product 75 0.2743 25 0.1, 10 zno nanoparticles 75 0.9363 25 0.1, 13 cuo nanoparticles 75 0.2743 0.9363 25 0.1, 13 zno/cuo nanoparticles table 2. compares the use of nanoparticles of chitosan, zno, cuo, and zno/cuo in the synthesis of all films film the comparison between chitosan and zno, cuo and zno/cuo nanoparticles chitosan (g) mass (g) of metal oxide nanoparticles a 0.1 0.1 (zno nanoparticles) b 0.1 0.1 (cuo nanoparticles) c 0.1 0.1 (zno/cuo nanoparticles) d 0.1 0.2 (zno/cuo nanoparticles) e 0.2 0.1 (zno/cuo nanoparticles) oxide nanoparticles film as an antibacterial agent and the antibacterial procedure was adopted from fatoni et al. (2022) . the procedure from isnaeni et al. (2020) was used to prepare the inoculum of the bacterial suspension. the film (1 cm × 1 cm) was pasted in the second layer of nutrient agar. the second layer of nutrient agar contained the bacterial suspension. the petri plate was incubated at 37°c for 24 h. the diameter of the inhibition zone was measured after 24 h. 3. results and discussion 3.1 biosynthesis metal oxide nanoparticles the process of biosynthesis of metal oxide nanoparticles was illustrated as seen in figure 2. the materials were used in the biosynthesis of metal oxide nanoparticles such as ethanolic extract of guava seed leaves, zinc acetate dihydrate, copper sulphate pentahydrate, and sodium hydroxide solution. ethanolic extract of guava seed leaves are containing active biomolecules: vitamins, tannin, alkaloids, carbohydrates, steroids, glycosides, and flavonoids (joseph et al., 2016) . the biomolecules were activated at ph 10 and this ph, the biomolecules will increase them as a capping and stabilizing agent because of its ability to change the electrical charges of biomolecules (khalil et al., 2014) . the product of biosynthesis zno, cuo and zno/cuo nanoparticles as seen in figure 3. the product of the film as shown in figure 4. 3.2 uv-vis spectroscopy analysis the optical properties and electronic structure of metal nanoparticles were analyzed by uv–vis spectroscopy such as the absorption peaks (dobrucka et al., 2019) . surface plasmon absorption (spa) causes absorption peaks (rajendrachari et al., 2021) . the biosynthesis of zno, cuo, and zno/cuo nanoparticles figure 2. biosynthesis of metal oxide nanoparticles figure 3. documentation picture of zno, cuo, and zno/cuo nanoparticles in (a), (b), and (c), respectively were analyzed by uv-vis spectroscopy and shown in figure 5. in figure 5, the specific uv absorbance for zno, cuo, and zno/cuo nanoparticles at 250, 272 and 270 wavelengths respectively. the wavelength at 250 nm for zno nanoparticles. this peak is lower than 300 nm and as per the previous literature (dobrucka and długaszewska, 2016) . the peak at 272 nm for cuo nanoparticles is still below the results of © 2023 the authors. page 375 of 381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 table 3. the inhibition zone of all films film the film of: the inhibition zone (mm) petri plate 1 petri plate 2 petri plate 3 average ± sd a chitosan-zno nanoparticles 26.36 25.87 25.93 26.03 ± 0.21 b chitosan-cuo nanoparticles 19.48 19.52 17.63 18.87 ± 0.88 c chitosan-zno/cuo nanoparticles (type a) 22.99 20.69 23.53 22.40 ± 1.23 d chitosan-zno/cuo nanoparticles (type b) 26.25 26.98 27.70 26.97 ± 1.53 e chitosan-zno/cuo nanoparticles (type c) 19.38 18.49 19.38 19.08 ± 0.41 f chitosan figure 4. the photograph of chitosan film (a), chitosan-cuo nanoparticles film (b, film b) and chitosan-zno nanoparticles film (c, film a), chitosan-zno/cuo nanoparticles film (d, film c), chitosan-zno/cuo nanoparticles film (e, film e) and chitosan-zno/cuo nanoparticles film (f, film d) research by bhavyasree and xavier (2020) . there is a transition of electrons from the valence band to the conduction band of cuo even with a weak absorption band. the peak for zno/cuo nanoparticles at 270 nm is a similar peak to the study of asamoah et al. (2020) . in this peak, the transition from the 2p of oxygen to the 4s of cu2+ was observed. figure 5. profile of uv-vis spectra zno, cuo, and zno/cuo nanoparticles 3.3 functional group analysis the ftir spectra of zno, cuo and zno/cuo nanoparticles as seen in figure 6. the interpretation of spectra in figure 6 shows, the band region at 3423-3448 cm−1 can be noted to stretching vibration of o-h and n-h from a secondary metabolite as a bioactive figure 6. ftir spectra of cuo nanoparticles, zno nanoparticles and zno/cuo nanoparticles compound (matinise et al., 2017) . the band at 929-1620 cm−1 is due to c=c, c=n, and c=o (matinise et al., 2017) . the characteristic of metal oxides has an absorption band below 1000 cm−1 because of interatomic vibration (matinise et al., 2017) . the peak at 503 and 619 cm−1 is the stretching vibration of the cu-o (hemalatha and makeswari, 2017; berra et al., 2018; altikatoglu et al., 2017). the zn-o (stretching vibration) shows at 468-675 cm−1 (dobrucka and długaszewska, 2016; jan et al., 2021; mydeen et al., 2020) and a stretching vibration of zn-o/cu-o observed at 497 and 619 cm−1 (fouda et al., 2020) . the ftir spectra of chitosan film, film a and b as displayed in figure 7 and film c, d, and e as seen in figure 8. © 2023 the authors. page 376 of 381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 figure 7. ftir spectrum of chitosan film, chitosan-zno nanoparticles film (film a) and cuo nanoparticles film (film b) figure 8. ftir spectra of film c, d and e chitosan film (figure 7) showed bands at 3448 cm−1, 2920 cm−1, 1656 cm−1, and 1595 cm−1, which were investigated to the o-h/n-h stretching, c-h stretching, amide-i, and amideii groups, respectively (krishnan et al., 2020) . in figure 7 and 8, the ftir spectra of film a-e has a characteristic band between 3273 and 3446 cm−1 and show the overlap of stretching vibration of –nh and –oh groups. all these bands are lower than a band of stretching vibration of –nh and –oh groups chitosan film (3448 cm−1). the peaks at amide-i of chitosanzno nanoparticles film and chitosan-cuo nanoparticles film shifted to lower wavenumber (1656 to 15741614 cm−1). the decrease in wavenumber shows the interaction of –nh, –oh, and amide-i groups of chitosan with zno or cuo through a hydrogen bond (prokhorov et al., 2020) . 3.4 analysis of physical structure the analysis of physical structure of zno, cuo and zno/cuo nanoparticles as seen in figure 9. figure 9. diffractogram of zno nanoparticles, cuo nanoparticles and zno/cuo nanoparticles figure 10. diffractogram of chitosan film, chitosan-zno/cuo nanoparticles film (film c), chitosan-zno/cuo nanoparticles film (film d) and chitosan-zno/cuo nanoparticles film (film e) the peaks observed at 2\ = 13.95°, 16. 42°, 33.5°, and 59.54° (figure 9, zno nanoparticles). these peaks showed a crystalline form for zno nanoparticles (sharmila et al., 2018; kalpana et al., 2018). in figure 9 (cuo nanoparticles), the sharp peak at 2\ ≈ 32.21° is a crystalline form for cuo nanoparticles (murthy et al., 2021) . the diffractogram zno/cuo nanoparticles has peaks at 2\ values of 32.31°, 34.40° and 60.23°. these peaks are the peaks of cuo nanoparticles (murthy et al., 2021) . the difference between diffractogram of cuo nanoparticles and zno/cuo nanoparticles is the presence of zno nanoparticles peaks in diffractogram of zno/cuo nanoparticles. the crystallite size of the biosynthesized zno, cuo, and zno/cuo nanoparticles was calculated by a debye scherrer’s © 2023 the authors. page 377 of 381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 figure 11. surface morphology of chitosan film (a), chitosan-cuo nanoparticles film (b), chitosan-zno nanoparticles film (c) and chitosan-zno/cuo nanoparticles film (d, film d) figure 12. the antibacterial study of film a, b, c, d, e and f (chitosan film as control) formula (chinnathambi and alahmadi, 2021) . d = 0.9._ 𝛽 .cos\ where d, _ , 𝛽 and \ are the crystallite size, the wavelength, the full width at half maximum (fwhm) and bragg’s angle respectively. the crystallite size of the biosynthesized zno, cuo, and zno/cuo nanoparticles were estimated 13.21, 13.21 and 11.49 nm respectively. the physical structure of chitosan film, chitosan-zno/cuo nanoparticles film, chitosan-zno/cuo nanoparticles film, and chitosan-zno/cuo nanoparticles film as seen in figure 10. the xrd pattern of chitosan film (figure 10) shows the peak at 2\ ≈ 14.3° and 20.6°. these peaks are in hydrate crystalline form (prokhorov et al., 2020) . the peaks that appeared in the chitosan-zno/cuo nanoparticles film (film c, figure 10) have 2\ ≈ 12.44°, 15.17°, 24.70° and 64.00°. the xrd pattern of film d (figure 10) shows the peak at 2\ ≈ 24.30°, 31.59°, 37.58°, and 77.10°. film e (figure 10) contained 2\ ≈ 11.00°, 22.70° and 66°. the peak of 2\ chitosan in films c and e was detected at 12.44° and 11.00° respectively. this peak is lower than the peak of film chitosan and showed an increase in the degree of amorphous form because of the interaction between the n-h and o-h groups in chitosan with zno/cuo nanoparticles (prokhorov et al., 2020) . the peak of chitosan in film d was observed at 2\ = 24.30°, sharma et al. (2012) reported that the peak at 2\ = 24° was the amorphous region of the film chitosan. in the film, c, d, and e, the peaks of zno/cuo nanoparticles were observed as reported in previous study (sharmila et al., 2018; logpriya et al., 2018) and showed that chitosan associated with zno and cuo nanoparticles. 3.5 analysis of surface morphology the scanning electron micrographs for chitosan and modified chitosan as seen in figure 11. the sem image of a chitosan film (figure 11(a)) showed that it had a nonporous surface and irregular form depending on the degree of acetylation and molecular weight (lópezmata et al., 2013) . the addition of zno, cuo, and zno/cuo nanoparticles in chitosan caused morphological differences at the surfaces of the film (figure 11(b,c,d)). the interaction of metal oxide nanoparticles can change the chitosan surface (aljuhani et al., 2021) . the surface of chitosan-zno/cuo nanoparticles film is different than chitosan-zno nanoparticles film or chitosan-cuo nanoparticles film because the amount of cu2+ ion is higher than zn2+ ion. 3.6 antibacterial study of all films the antibacterial study of all films was investigated using the agar diffusion method. this method is simple, cheap, can be used to test a high number of microorganisms and antimicrobial as sample and the ease to explain the results of the data obtained (balouiri et al., 2016) . the data can be seen in figure 12. the inhibition zone of all films was calculated and tabulated in table 3. table 3 showed the average zone of inhibition of d > a > c > e > b > f film against escherichia coli bacteria. the presence of zno or cuo nanoparticles in the a-e films can increase the antimicrobial properties of the film. the mechanism of the film a-d is the antimicrobial activity as reported by the previous literature. the existence of pores in the outer cell wall of escherichia coli bacteria can accelerate zno or cuo nanoparticles go into the pores (el fawal et al., 2020) , zno or cuo nanoparticles will release the reactive oxygen species (ros) and zn2+ or cu2+. both of them will attack the negative charge of the bacterial cell wall and its effect, disturbing the synthesis of protein of bacteria (rahman et al., 2018) . dananjaya et al. (2018) as previous researcher concluded that electrostatic attraction can inhibit the growth of bacteria due to the interaction of the positive surface charges of chitosan-metal oxide nanoparticles and the negative charge of the bacterial cell walls. © 2023 the authors. page 378 of 381 fatoni et. al. science and technology indonesia, 8 (2023) 373-381 4. conclusion zno, cuo, and zno/cuo nanoparticles can be biosynthesized successfully and the third of metal oxide nanoparticles were used as material in the synthesis of chitosan-metal oxide nanoparticles film. the ftir spectrum from metal oxide nanoparticles and all films indicated the functional group and structure of metal oxide nanoparticles. xrd pattern of metal oxide nanoparticles and all films indicated the crystalline of metal oxide nanoparticles and amorphous form respectively. the surface morphology of the d film is clear than the chitosan film. the antibacterial activity of d film is higher than a, b, c, and e. 5. acknowledgment we would like to thank stifi bhakti pertiwi for funding this research. thank you to laboratorium fisika terpadu itb for the morphology surface analysis. references adeyemi, j. o., d. c. onwudiwe, and a. o. oyedeji (2022). biogenic synthesis of cuo, zno, and cuo–zno nanoparticles using leaf extracts of dovyalis caffra and their biological properties. molecules, 27(10); 3206 al-dahash, g., w. mubder khilkala, and s. n. abd alwahid (2018). preparation and characterization of zno nanoparticles by laser ablation in naoh aqueous solution. iranian journal of chemistry and chemical engineering, 37(1); 11–16 aljuhani, a., s. m. riyadh, and k. d. khalil (2021). chitosan/cuo nanocomposite films mediated regioselective synthesis of 1, 3, 4-trisubstituted pyrazoles under microwave irradiation. journal of saudi chemical society, 25(8); 101276 altikatoglu, m., a. attar, f. erci, c. m. cristache, i. isildak, et al. 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1–22 solanki, p. r., a. kaushik, v. v. agrawal, and b. d. malhotra (2011). nanostructured metal oxide-based biosensors. npg asia materials, 3(1); 17–24 zhang, d., x.-l. ma, y. gu, h. huang, and g.-w. zhang (2020). green synthesis of metallic nanoparticles and their potential applications to treat cancer. frontiers in chemistry, 8; 799 © 2023 the authors. page 381 of 381 introduction experimental section materials and instruments ethanolic extract as medium in biosynthesis biosynthesis of metal oxide nanoparticles synthesis of the film characterization the antibacterial procedure of the film chitosan-metal oxide nanoparticles results and discussion biosynthesis metal oxide nanoparticles uv-vis spectroscopy analysis functional group analysis analysis of physical structure analysis of surface morphology antibacterial study of all films conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper interlayer modification of west java natural bentonite as hazardous dye rhodamine b adsorption satria jaya priatna1, yusuf mathiinul hakim2, sahrul wibyan3, siti sailah4, risfidian mohadi1,2* 1department of soil science, sriwijaya university, indralaya, 30862, south sumatera, indonesia2graduate school, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia3department of chemistry, faculty of mathematics and natural sciences, sriwijaya university, indralaya, 30862, south sumatera, indonesia4department of physics, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia *corresponding author: risfidian.mohadi@unsri.ac.id abstractthis work reports the modification of west java natural bentonite as an effective adsorbent for rhodamine b dye. the modificationwas finished by sodium intercalation at room temperature to get low-energy preparation. characterization of bentonite-modifiedadsorbent was used sem, xrd, ftir, and bet analysis. the material pore size and surface area were increased by 0.303 nm and178.710 m2/g on na-bentonite. the adsorption mechanism conformed well with the freundlich isotherm model and pseudo-second-order kinetics equations. the adsorption process by thermodynamic analysis was endothermic and advantageous. under theoptimum condition of ph 6 (confirmed by phpzc), initial dye concentration of 125 mg/l, and the adsorbent dosage of 0.09 g for 65minutes, the na-bentonite has a larger adsorption capacity (qm) of 142.86 mg/g, while the different adsorbent dosages of 0.11 g for75 minutes, the adsorption capacity of natural bentonite (qm) reaches 140.85 mg/g. this work provides a method for establishinga low-energy preparation adsorbent of bentonite-based on na-intercalant as a low-cost and valuable adsorbent for waste dyeremoval. keywordsbentonite, intercalation, low temperature, adsorption, rhodamine b received: 3 october 2022, accepted: 23 january 2023 https://doi.org/10.26554/sti.2023.8.2.160-169 1. introduction in recent years, environmental contamination has become a crucial issue due to the massive disposal of industrial waste (asgari et al., 2021; soleimani et al., 2022). massive wastewater disposed of led to contamination in the ecosystem (kamarehie et al., 2020; rahmani et al., 2022). coloring products are widely used in the food, cosmetics, pharmaceuticals, paints, and textiles industries (laysandra et al., 2017) . it was estimated that 7x105 tons of dye waste are produced annually (al tufaily and al qadi, 2016; mohammad et al., 2019). rhodamine b (rhb) is a basic cationic dye with complex structures shown in figure 1. in some cases, long-term exposure to rhb likely triggers temporary skin, and mucous membrane irritation, until the mutagenic effect (laysandra et al., 2017) . several works provide techniques to detach the pollutants such as precipitation, osmotic reverse, flocculation/coagulation, electrodialysis, and adsorption (dotto et al., 2019; giraldo et al., 2022; xie et al., 2022). adsorption becomes the most efficient due to the organics, toxic metals, and dye contaminants binding to the solid adsorbent. those stable contaminants bonded physically or chemically at the adsorbent surface (chai et al., 2020; mohammad et al., 2019). potential low-cost adsorbents that provide adsorption features are zeolites, limestone, silica gel, chitosan, dolomite, activated carbon, and bentonite/clay. nowadays, the layered material of alumina-silicate bentonite has gained popularity as a low-cost adsorbent due to its abundance and high potency to enhance adsorbing capacity. the limitation of natural bentonite due to its rigid structure and the negative charge that is only sensitive to removing cationic dyes have encouraged researchers to modify the bentonite structure (ding et al., 2018) . however, the intercalation of natural bentonite by cationic exchange assisted by calcination to increase the adsorption capacity is favorable (srikacha et al., 2022) . however, the intercalation step may need a longer preparation time of 3 h to 10 days, moreover calcination process of more than 300°c to change the bentonite structure could trigger a collapse of the bentonite structure (bouras et al., 2007; leodopoulos et al., 2015). recently, islam and mostafa https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.160-169&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.160-169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 figure 1. chemical structure of rhb dye (2022) studied the natural sodium bentonite adsorption capacity towards methylene blue by an adsorption capacity of 25.19 mg/g. according to shattar and foo (2022) , activation bentonite assisted by sodium salt under heating of 70°c gives removal of methylene blue with an adsorption capacity of 318.38 mg/g. the intercalation process becomes a challenge in bentonite modification. the rigid characteristics of the bentonite structure block the intercalation of another molecule. sodium intercalation, as the preliminary step, becomes the favorable solution. the opening interlayer process to insert the intercalant need some energy that uses heat and pressure. high energy insertion is the challenge to discover a new method of the intercalating molecule to increase the interlayer bentonite. according to the report of lin et al. (2007) , intercalation via intermolecular force becomes an effective method for inserting molecules in low temperatures to decrease energy consumption. this work aims to intercalate the west java natural bentonite by saturated sodium salt solution under the natural ambiance of low-temperature preparation to get intramolecular force in inserting the intercalant and evaluate its removal capacity on rhb from aqueous solutions. sodium salt was chosen because it is non-toxic to essential substances in the environment and has a high cationic exchange capacity in bentonite surfaces (alexandru, 2011) . the bentonite-modified characterization used sem, xrd, ftir, and bet to analyze physicochemical structural changes. the adsorption mechanism of rhb was carried out with optimization of the operational condition by phpzc, variations in time, the dosage of adsorbent, temperature, and initial concentration. 2. experimental section 2.1 chemicals and instrumentation the natural bentonite was obtained from west java with purification. chemicals in a pure grade, such as sodium chloride (nacl), sodium hydroxide (naoh), silver nitrate (agno3), hydrochloric acid (hcl), and rhodamine b (rhb) dye, were purchased from sigma-aldrich and directly used without purification. instrumentation such as x-ray diffractometer (xrd) type rigaku mini-flex600, fourier transfer infra-red (ftir) type perkin-elmer uatr spectrum two, uv-vis spectrophotometer type orion aquamate 8000, scanning electron microscope energy dispersive spectrometer (sem-eds) type jeol jsm 6510-la, and surface area analyzer using quantachrome asiq-win based on bet method calculation. 2.2 bentonite intercalation the natural bentonite was modified by the cationic exchange methods at room temperature of 25°c: 100 g of natural bentonite dissolved in 333 ml of saturated nacl and stirred for 2 hours. then the mixture was added with distilled water (by two times the mixture volume) and continued stirring for 10 minutes. the bentonite mixture was precipitated and repeatedly added with 333 ml saturated nacl, then mixed for 2 hours. it was washed three times with boiled distilled water, and the precipitate was oven-dried at 200ºc for 12 hours. it is noticed as na-bentonite. 2.3 optimization of operational condition the phpzc (point zero charges) was determined by adding 0.02 g of adsorbent into 20 ml of 0.1 m nacl solution and adjusted to ph of 2, 3, 4, 5, 6, 7, 8, 9, 10 using 0.1 m of naoh and hcl solution. the mixture was stirred for 3 hours, and the final ph of the filtrate was measured using a ph meter to graph the phpzc state. 2.4 adsorption studies the effect of adsorption time was studied by varying the time adsorption at 5, 15, 25, 35, 45, 55, 65, 75, and 85 minutes. the composition of the adsorption process is 0.01 g of adsorbent into 50 ml of 30 mg/l rhb dyes. the effect of adsorbent dosages was studied by variation of adsorbent dosages at 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, and 0.13 g. the effect of temperature and concentration adsorption was conducted on the adsorption of rhb using various temperatures and initial concentrations at 30, 40, 50, 60, and 70°c, with the concentration of rhb 25, 50, 75, 100, and 125 mg/l. 2.5 analysis of mechanism adsorption adsorption kinetics of this experiment conducted by wu et al. (2021) for pseudo-first order and pseudo-second order kinetic models are shown in equation 1 and 2, respectively: ln(qe − qt) = lnqe − tk1 (1) t qt = 1 q2e + t qe (2) where k1 is the rate constant of pseudo-first order (min−1), k2 is the constant rate of pseudo-second order (g.mg−1min−1), t for time, then qe and qt are capacity adsorption at equilibrium © 2023 the authors. page 161 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 and specific time, respectively. the langmuir and freundlich adsorption isotherm were analyzed to know the adsorption isotherm of this experiment according to sahnoun et al. (2018) by the equation, respectively: ce qe = 1 qmaxkl + ce qmax (3) lnqe = lnkf + lnce n (4) where qe is the capacity equilibrium of adsorbent (mg/g), ce is the concentration equilibrium after adsorption (mg/l), qmax is the capacity maximum of adsorption (mg/g), kl is constant of langmuir adsorption (l/mg), then kf and n are constant of freundlich adsorption (l/g). furthermore, the thermodynamic parameters can be analyzed by following equations (dotto et al., 2019) : δg = −rtlnkd (5) δg = δh −tδs (6) lnkd = δs r − δh rt (7) where δg° is the value of free energy gibbs (kj/mol), δh° is the enthalpy change of adsorption (kj/mol), δs° is adsorption entropy change (kj/mol.k), r is the standard gas constant (8.324 kj/mol), t is temperature reaction (k), and kd is the equilibrium constant. 3. result and discussion 3.1 characterization of adsorbents the morphologies of modified bentonite were observed using sem techniques in figure 2 shows a massive quantity of lamellar particles with unshaped aggregated and rough particles attached to the surface area, especially in modified bentonite in figure 2b (mahmoodi, 2015) . aggregate and rough particles may be impurities from zeolite, while according to figure 2a, the flake’s structures are considered montmorillonite(jiang et al., 2021) . according to figure 2b, lamellar structures in nabentonite present numerous small particles attached. those phenomena showed that cation exchange significantly reduced impurities, confirmed by detailed edx data in table 1. the intercalation process affected the removal of the ti substance. the composition and structural changes are reflected by xrd analysis in figure 3. the basal spacing of the bentonitemodified adsorbents is 8.06 nm and corresponds to the d001 peak, the value of 2\ about 20°, noticed as montmorillonite. figure 2. sem image of (a) natural bentonite (b) na-bentonite the sodium-intercalated did not change significantly due to low interaction binding and the size particle of sodium identic to the previous cation in the interlayer. unfortunately, the sodium intercalation has affected the cationic exchange, and it is confirmed from figure 3 that the peak positions of all adsorbents are similar (he et al., 2022) . according to the data of xrd, the crystal size of natural bentonite and na-bentonite are 4.35 nm and 8.06 nm, respectively. modifying bentonite assisted by sodium intercalation between interlayers increases the montmorillonite composition, layer space, and adsorption capacity by providing the cationic exchange field. according to jcpds data no. 24-0495 shows that 2\ at around 20°, 35°, 55°, and 63° are montmorillonite compounds. then, for 2\ at about 26° are quartz compounds, while at 2\ around 28° are compounds composed of al, si, and o (reza et al., 2015) . figure 3. xrd patterns of (a) natural bentonite and (b) na-bentonite bentonite, as layered material, has several functional groups that influence adsorption. the ft-ir spectrums of bentonitemodified are displayed in figure 4. the composition of oh octahedra stretching vibrations at the surface layer is indicated by a peak at 3380 cm−1 . a peak indicates the h-o-h vibrations of the water molecule at 1632 cm−1 . the layer structures of bentonite were confirmed by stretching vibrations of si-o© 2023 the authors. page 162 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 table 1. edx data of bentonite-modified adsorbent element natural bentonite (%w) na-bentonite (%w) o 57.88 54.83 si 22.17 22.86 c 13.02 10.77 al 3.32 4.21 fe 1.34 1.42 mg 0.71 0.69 cu 0.62 1.10 ca 0.27 1.59 k 0.26 0.48 na 0.23 0.84 ti 0.17 table 2. the analysis of bet surface area, pore diameter, and pore volume of the natural bentonite and na-bentonite adsorbent bet surface area (m2/g) pore diameter (nm) pore volume (cm3/g) natural bentonite 61.791 4.678 0.144 na-bentonite 178.710 3.401 0.303 si from the peak at 1028 cm−1 and vibrations of al-o-al from the peak at 791 cm−1 (castellini et al., 2017) . the peak at 518 and 459 cm−1 is ascribed to the cation vibration on the layer structure of bentonite. the difference in peak sharpness affected vibration intensity due to sodium salt intercalant power binding at the surface interlayers, thus giving additional functional groups between interlayers (yang et al., 2022) . the textural characteristics of natural bentonite and the intercalated one were characterized via the n2 adsorptiondesorption method at 77.35 k. detailed result was plotted in the graph of n2 adsorption-desorption isotherm characteristics in figure 5. the isotherm trend from the natural bentonite and na-bentonite behave in the same condition that fits into the type iv according to braunnauer-deming-deming-teller (bdtt) classification (mu’azu et al., 2018) . the overlapping of adsorption-desorption points occurred at the low relative pressure; thus fit with the h3 type of hysteresis loop that initiated at a relative pressure (p/p0) around 0.42. the emerging features are grouped as the characteristic of the mesopore layered material (tong et al., 2018; yurdakal et al., 2019). the precise surface area value calculated using the bet model on natural and na-bentonite is tabulated in table 2. in this case, the specific surface area of bentonite-intercalated na+ was differently higher than the natural one. it assumed that sodium intercalations’ effectivity significantly impacts the active surface of adsorbent-adsorbate interaction in multiple quantities and generates additional mesopores (javed et al., 2018) . despite the decreasing pore diameter, the pore volume was increasing due to the enormous size of intercalate, thus promoting the adsorption process (ain et al., 2020; mohammed and isra’a, 2018). figure 4. ft-ir spectrums of (a) natural bentonite and (b) na-bentonite 3.2 optimization of operational conditions the phpzc of bentonite-based adsorbent was plotted by al maliky et al. (2021) in figure 6, which turned out to be 4.35 for natural bentonite and 5 for na-bentonite provides an acid medium for adsorption of dyes. the role of phpzc is to determine the influence of ph range on the active site of the surface adsorbent. the value of ph > phpzc induces optimum adsorption of cationic dyes due to negative charge increases on adsorbent (kanwal et al., 2022) . rhb has a positive charge in the solvent, then tends to adsorb at a higher ph value than the phpzc condition (ribeiro dos santos et al., 2019) . it is appropriate for the experiment due to the optimum adsorption © 2023 the authors. page 163 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 table 3. adsorption kinetic model model parameter adsorbent adsorbent kinetics adsorption natural bentonite na-bentonite qe (mg/g) 102.49 119.22 pseudo first order k1 0.062 0.058 r2 0.926 0.883 qe (mg/g) 102.49 102.49 pseudo second order k2 0.006 0.007 r2 0.9975 0.9978 table 4. parameter of isotherm adsorption of rhb on the bentonite-modified adsorbent adsorbent isotherm model parameter adsorption temperature (°c) 30 40 50 60 70 langmuir qm 140.85 133.33 138.89 125 123.46 kl 0.023 0.033 0.034 0.057 0.114 natural bentonite r2 0.930 0.913 0.914 0.919 0.809 freundlich n 1.506 1.641 1.647 1.808 2.244 kf 4.827 6.193 6.427 7.984 12.159 r2 0.995 0.991 0.991 0.987 0.946 langmuir qm 142.86 136.99 140.85 138.89 140.85 kl 0.035 0.054 0.063 0.078 0.107 na-bentonite r2 0.972 0.994 0.994 0.991 0.994 freundlich n 1.536 1.648 1.687 1.720 1.783 kf 5.725 7.037 7.628 8.093 8.978 r2 0.993 0.998 0.997 0.996 0.997 of rhb occurring at ph 6 based on preliminary laboratory screening. 3.3 effect of adsorption time the effect of variations in the contact time of bentonite-based adsorbent on rhb is seen in figure 7. figure 7 shows that the equilibrium adsorption time of rhb on natural bentonite reaches 75 minutes, while the equilibrium time on na-bentonite reaches 65 minutes. according to the literature, the calculated data of adsorption was gained using pseudo-first-order (pfo) and pseudo-second-order (pso) kinetic equations (mohadi et al., 2022) . the results of kinetic data adsorption on variation time adsorption are shown in table 3. based on table 3, the kinetic data shows that the linear regression value (r2) of the pseudo-second-order (pso) tends to be closer to 1 value than to the pseudo-first-order (pfo) kinetic model, so it concluded that rhb adsorption in bentonite-based adsorbent follows the pso model kinetics. it suggested that adsorption tends to occur by chemisorption, then the adsorption equilibrium rate is affected by the adsorbent and adsorbate composition (shattar and foo, 2022) . 3.4 effect of adsorbent dosage effect of variation dosages adsorption was prepared under room temperatures, ph = 6, adsorption time of 65 minutes for natural bentonite and 75 minutes for na-bentonite. figure 8 shows the adsorption rate for 30 mg/l rhb with a variation of bentonite-modified adsorbent dosages, where variation dosages were used from 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, and 0.13 g. based on figure 8, the equilibrium of adsorption rate of the natural bentonite and na-bentonite occurred at 0.11 g and 0.09 g, respectively, with insignificant increases at adsorbent dosages of more than 0.11g. the insignificant increase is related to the restricted concentration of dye that can be adsorbed and the agglomeration in bentonite adsorbent (khan et al., 2012) . 3.5 effect of concentration and adsorption temperature according to figure 9, the increases in adsorption temperature will cause a decrease in the adsorbate adsorbed for the rhb dye. otherwise, the concentration increases are affected by rhb adsorbed. data in tables 4 and 5 were used to determine the adsorption isotherm model using the langmuir and freundlich equation based on (sahnoun et al., 2018) . the data of the langmuir and freundlich isotherm calculation are shown in table 4. according to huang et al. (2017) , the langmuir isotherm model ascribed that adsorption occurs by the monolayer conformation on the surface of the adsorbent, thus not having interactions between molecules of adsorbate, while the freundlich © 2023 the authors. page 164 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 table 5. adsorption thermodynamic parameter data on natural bentonite consentration (mg/l) temperature (k) qe (mg/g) δh (kj/mol) δs ( j/k.mol) δg (kj/mol) 303 18.188 -2.218 313 19.233 -2.917 25 323 19.442 18.96 0.070 -3.616 333 20.278 -4.315 343 22.055 -5.014 303 31.568 -1.348 313 32.892 -1.599 50 323 33.380 6.24 0.025 -1.849 333 34.147 -2.099 343 34.983 -2.350 303 45.784 -1.117 313 46.411 -1.259 75 323 47.038 3.19 0.014 -1.401 333 47.874 -1.543 343 48.293 -1.685 303 58.536 -0.877 313 60.487 -1.062 100 323 61.463 4.72 0.018 -1.246 333 62.299 -1.431 343 64.111 -1.616 303 69.861 -0.590 313 71.777 -0.740 125 323 72.823 3.95 0.015 -0.890 333 73.171 -1.039 343 76.133 -1.189 figure 5. n2 adsorption-desorption properties isotherm ascribed that the adsorbent is supported multilayer and heterogeneous adsorption, thus adsorption process occurs by physical. based on table 4, the freundlich isotherm model shows a linear regression value (r2) closer to the value 1 than the langmuir isotherm model for rhb adsorption, indicating figure 6. the phpzc of (a) natural bentonite and (b) na-bentonite that rhb adsorptions are spread heterogeneously (xing et al., 2015) . the dimensions of the exponent 1/n state the favorable interaction between adsorbent-adsorbate. adsorption will be beneficial if n > 1. in this study, the adsorption of rhb is easy due to an n value higher than 1 (annadurai et al., 2000) . furthermore, according to huang et al. (2017) calculation © 2023 the authors. page 165 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 table 6. adsorption thermodynamic parameter data on na-bentonite concentration (mg/l) temperature (k) qe (mg/g) δh (kj/mol) δs ( j/k.mol) δg (kj/mol) 303 18.710 -2.747 313 19.616 -3.131 25 323 19.965 8.88 0.038 -3.515 333 20.174 -3.898 343 20.627 -4.282 303 43.742 -2.094 313 44.648 -2.379 50 323 44.997 6.54 0.028 -2.664 333 45.206 -2.949 343 45.659 -3.234 303 49.861 -1.720 313 50.592 -1.893 75 323 51.428 3.50 0.017 -2.065 333 51.951 -2.237 343 52.474 -2.410 303 61.324 -1.188 313 62.996 -1.328 100 323 63.554 3.06 0.014 -1.468 333 63.972 -1.609 343 64.947 -1.749 303 72.474 -0.822 313 74.216 -0.964 125 323 75.610 3.47 0.014 -1.105 333 76.133 -1.247 343 77.526 -1.388 figure 7. effect of contact time adsorption on (a) natural bentonite and (b) na-bentonite figure 8. effect of adsorbent dosage on (a) natural bentonite and (b) na-bentonite © 2023 the authors. page 166 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 table 7. comparative of adsorption capacity on rhodamine b in different adsorbent bentonite adsorbate adsorption capacity (mg/g) optimum time (minutes) references na-bentonite rhb 142.86 65 this study bentonite-cta-daptms rhb 0.98 5 de morais pinos et al. (2022) 𝛾fe2o3/montmorillonite rhb 45.08 60 fatimah et al. (2022) beta zeolite sio2/al2o3 rhb 27.97 60 cheng et al. (2018) 𝛼-al2o3 rhb 52 30 yen doan et al. (2020) figure 9. effect of temperature and concentration adsorption of rhb on (a) natural bentonite and (b) na-bentonite figure 10. mechanism interaction proposed of rhb adsorption bentonite-modified of thermodynamic parameters can provide data (δg°), (δs°), and (δh°). the detail of the thermodynamic parameter data is shown in tables 4 and 5 . the calculation results for δg° value are negative on each adsorbent; thus, the value decreased with increasing adsorption temperature. a negative value of δg° indicates that the rhb adsorption process is beneficial and spontaneously occurs he et al. (2022) , and the adsorption is better at high temperatures. the δh° value showed a range of 18.96 kj/mol to 3.95 kj/mol was related to the tendency of rhb adsorption to occur by physical adsorption and endothermic based on a positive δh° value, thus supporting the isotherm adsorption analysis. the adsorption mechanism of rhb into bentonite-modified adsorbent visualized in figure 10. physisorption as dominant mechanism take a apart in bentonite negative charge of surface, then the cation exchange of rhb into interlayer bentonite has reduce the sodium ion in the interlayer structure (selvam et al., 2008) . another result is the positive value of δs°, which is related to the irregularity of the particles during adsorption increases due to the adsorbentliquid interaction between the bentonite-based adsorbent and rhb (mahmoodi, 2014) . 4. conclusion in summary, the new route modification of natural bentonite imported from west java of indonesia was completed using cation exchange of sodium salt-intercalant under low room temperature of 25°c to develop efficient and low energy prepared adsorbent to remove rhb dyes in an aqueous solution. the bentonite-modified was characterized by several characterization techniques, indicating the sodium was intercalated on the interlayer bentonite. the adsorption study proved that nabentonite effectively removed the rhb with adsorption capacity (qm) reached 142.86 mg/g for na-bentonite by physisorption and spontaneously endothermic occurred. 5. acknowledgment the research of this article was funded by dipa of public service agency of universitas sriwijaya 2022. sp dipa23.17.2.677515 /2022, on desember 13, 2021. under the rectors decree 0017/un9.3. 1 /sk.lp2m.pt/2022, on juni 15, 2022. references ain, q. u., u. rasheed, m. yaseen, h. zhang, r. he, and z. tong (2020). fabrication of magnetically separable 3-acrylamidopropyltrimethylammonium chloride intercalated bentonite composite for the efficient adsorption of cationic and anionic dyes. applied surface science, 514; 145929 al maliky, e. a., h. a. gzar, and m. g. al azawy (2021). determination of point of zero charge (pzc) of concrete particles adsorbents. iop conference series: materials science and engineering, 1184(1); 012004 al tufaily, m. and z. al qadi (2016). preparation and utilization of corncob activated carbon for dyes removal from aqueous solutions: batch and continuous study. journal of babylon university/engineering sciences, 2(3); 24 © 2023 the authors. page 167 of 169 priatna et. al. science and technology indonesia, 8 (2023) 160-169 alexandru, i. 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(photo) catalyst characterization techniques: adsorption isotherms and bet, sem, ftir, uv–vis, photoluminescence, and electrochemical characterizations. heterogeneous photocatalysis, 4; 87–152 © 2023 the authors. page 169 of 169 introduction experimental section chemicals and instrumentation bentonite intercalation optimization of operational condition adsorption studies analysis of mechanism adsorption result and discussion characterization of adsorbents optimization of operational conditions effect of adsorption time effect of adsorbent dosage effect of concentration and adsorption temperature conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper spatial autoregressive quantile regression with application on open unemployment data ferra yanuar1*, tasya abrari1, izzati rahmi hg1, aidinil zetra2 1department of mathematics and data science, andalas university, 25163, indonesia2department of political sciences, andalas university, 25163, indonesia *corresponding author: ferrayanuar@sci.unand.ac.id abstractthe open unemployment level (oul) is the percentage of the unemployed to the total labor force. one of the provinces withthe highest oul score in indonesia is west java province. if an object of observation is affected by spatial effects, namely spatialdependence and spatial diversity, then the regression model used is the spatial autoregressive (sar) model. quantile regressionminimizes absolute weighted residuals that are not symmetrical. it is perfect for use on data distribution that is not normallydistributed, dense at the ends of the data distribution, or there are outliers. the spatial autoregressive quantile regression (sarqr)is a model that combines spatial autoregressive models with quantile regression. this research used the data regarding our in westjava in 2020 from the central bureau of statistics. this study develops to modeling the open unemployment level in all province inindonesia using modified spatial autoregressive model with the quantile regression approach. this study compares the estimationresults based on sar and sarqr models to obtain an acceptable model. in this study, it was found that the sarqr model isbetter than sar at dealing with the problems of dependency and diversity in spatial data modeling and is not easily affected by thepresence of outlier data. keywordsopen unemployment level (oul), spatial effects, sar, sarqr, the outlier received: 10 january 2023, accepted: 11 april 2023 https://doi.org/10.26554/sti.2023.8.2.321-329 1. introduction unemployment is a phenomenon that occurs in all developing countries, including indonesia. one of the causes of unemployment is the lack of job opportunities that are not balanced by the number of job seekers in an area. this leads to an increase in the number of unemployed. an indicator to measure high unemployment in an area is the open unemployment level (oul). oul is the percentage of unemployed in the total labor force. west java province is one of indonesia’s top three provinces with the highest open unemployment level. the oul situation in west java province in august 2021 was 9.82 percent, down 0.64 percentage points compared to august 2020 (central, 2021) . however, this value is still too high above the national average. it is necessary to identify which factors are significant in reducing oul. factors between regions usually tend to be involved as one factor affecting oul in an area (dai and jin, 2021; weisberg, 2014), known as spatial effects. spatial effects are divided into two parts: spatial dependence and spatial diversity. spatial dependence occurs due to the relationship between regions, while spatial diversity occurs due to the diversity between one region and another. if this happens, the data modeling method used is the spatial autoregressive (sar) regression method (ver hoef et al., 2018) . the existence of outlier data will also affect the modeling method used (yanuar et al., 2023) . influential outlier data cannot be thrown away because it will eliminate important information related to the data (yasin et al., 2020; yasin et al., 2022). modeling for data containing spatial effects and outliers uses the spatial autoregressive quantile regression (sarqr) method (dai and jin, 2021; dai et al., 2020; jin et al., 2016). there has recently been an increase in the research on estimating and testing spatial autoregressive quantile models. jin et al. (2016) explored the quantile regression approach for partially linear spatial autoregressive models with possibly varying coefficients using b-spline. (dai et al., 2022) . dai et al. (2020) investigated fixed effects quantile regression for general spatial panel data models with both individual fixed effects and time effects based on the instrumental variable method. dai and jin (2021) employed the minimum distance quantile regreshttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.321-329&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.321-329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 sion (mdqr) methodology for estimating the sar panel data model with individual fixed effects. zhang et al. (2021a) studied a penalized quantile regression for a spatial panel model with fixed effects. to fill the research gap, this study applied a sarqr model that integlevels the spatial correlations and quantile effects to estimate the effects of regional factors on the open unemployment level in west java province and how they vary with the figure of the open unemployment level. it aims to answer the following questions: how sar and sarqr can produce the acceptable model of open unemployment level?, what are the effects of risk factors of open unemployment level, and how do they vary across the distribution of the open unemployment level?, how does the open unemployment level affect the above effects?. the rest of the study is organized as follows. section 2 describes the available data used in this study. section 3 introduces the sar and sarqr models. section 4 reports the modelling results and discusses the parameter estimations. section 5 summarizes the remarkable findings and gives further directions. 2. experimental section 2.1 materials in this section, the data used in this study is secondary data obtained from the central bureau of statistics for west java province from 1 january to 31 december in 2020 (central, 2021) . west java province consists of 18 regencies and 9 cities. the variable used is the percentage of the population (x1), which is the total population in the district/city divided by the total population of the province multiplied by 100%, the percentage of poor people (x2), the labor force participation level or lfpr (x3), abbreviated gross regional domestic product or grdp (x4) and the percentage of human development index or % hdi (x5) (candraningtyas and santosa, 2022; hapsari and hasmarini, 2022). the response variable is the open unemployment level or oul . 2.2 methods to apply the sar method, several stages of testing are required to ensure that the sar method is suitable for modelling the cases raised. multicollinearity is a condition with a correlation between the independent variables in the regression model. multicollinearity can be detected using the variance inflation factor (vif) value as follows (xu and huang, 2015) : vif1 = 1 1 − r21 (1) with rl 2 is determinant coefficient for predictor variable l, for l = 1,. . . , p. if the vif value is less than 5, multicollinearity does not occur in the regression model (yu et al., 2021) . a spatial weighting matrix is a matrix that describes the relationship of each region. the spatial weighting matrix is denoted by w with size n×n, where n represents the number figure 1. box plot of variables (a) % population (x1), (b) % poor population (x2), (c) lfpr (x3), (d) grdp (x4), (e) % hdi (x5), and (f) oul (y) of observation areas. the spatial weighting matrix is obtained based on the results of standardized contiguity. matrix contiguity has three types of contact, namely rook contiguity (side contact between regions), bishop contiguity (corner contact between regions) and queen contiguity (side touch and corner points between regions). matrix contiguity has a value of 1 if between regions meet the type of contact (dai and jin, 2021; yasin et al., 2020). 2.3 spatial effects spatial effects consist of spatial dependence and spatial diversity. to determine the existence of spatial dependence between regions, a test was carried out with the moran index. moran’s index measures the relationship of observations between an area and other areas close to each other. moran’s index is defined as follows (tribhuwaneswari et al., 2022) : i = n ∑n i=1 ∑n j=1 wi j(yi − ȳ)(yj − ȳ)∑n i=1 ∑n j=1 wi j ∑n j=1(yj − ȳ)2 (2) © 2023 the authors. page 322 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 figure 2. spatial distribution of open unemployment level in west sumatra (in percentage) = ∑n i=1 ∑n j=1 wi j(yi − ȳ)(yj − ȳ) s2 ∑n i=1 ∑n j=1 wi j with i and j are the number of data (n), for i≠j, yi is the response variable for all observations i, ȳ is the mean of y, wi j is element of spatial weighting matrix w, and s2 is sample variance. if i is positive, adjacent areas have similar values, and the data pattern tends to be clustered. if i is negative, it means that adjacent areas have different values, and the data pattern tends to spread out. if i is 0, it means no spatial dependence detected (huang et al., 2010) . the existence of spatial dependence on the dependent variable is also checked in the hypothesis model. the lagrange multiplier test is used to determine spatial dependence, with the general form of the lagrange multiplier as follows (anselin and anselin, 1988) : lmlag = ( u′wy s2 )2 np (3) with np = t + (wx 𝛽)′m(mx 𝛽) s2 , t = trace((w +w ′)w ), m = i − x(x′x)−1x′, s2 = u′u n , u as a remainder. where x is matrix of independent variables of size n ×(k+1) and 𝛽 is factor of the regression coefficient of size (k+1) ×1. if the lm lag> x2𝛼,1, it indicates that there is a spatial dependence on the dependent variable. if a model contains spatial dependence, the modelling is carried out using a spatial autoregressive model (anselin and anselin, 1988) . as for detecting spatial diversity, it can use the breush-pagan (bp) test with the following formula: bp = 1 2 ( f ′x)(x′x)−1(x′ f ) (4) where f is a vector where its elements are û2i �̂� -1 while û1 is observation from the regression estimation result and �̂� is the variance of the residuals, if the bp >x2𝛼,k−1 means that there is spatial variation between observation areas at significant 𝛼. parameter k represent the number of independent variables involves in the model. 2.4 quantile regression the quantile regression method uses the approach of separating the data into certain quantile groups that may have different estimated values (yanuar et al., 2022; yanuar et al., 2019). the linear regression equation model for the quantile 𝜏 is as follows (davino et al., 2013; yanuar and zetra, 2021): y = x 𝛽𝜏 +u , (5) y = vector of dependent variables of size n × 1, x : matrix of independent variables of size n × (k + 1), 𝛽𝜏 : factor of the regression coefficient of quantiles of size(k + 1) × 1depending on the quantile−𝜏 , u : vector of residuals of size n × 1. the parameter estimation using the regression quantile method is obtained by minimizing the sum of the absolute values of the errors with weights 𝜏 for positive errors and (1-𝜏) for negative errors, formulated as follows: arg min𝛽 ∈\ n∑︁ i=1 𝜌𝜏 (yi − xi 𝛽i) with loss function 𝜌𝜏 (u)=[𝜏-i(u<0)]u. where i(.) is the indicator function, its value is one when i(.) is accurate and zero otherwise. while 𝜌𝜏 (u) is the loss function which is defined as follows 𝜌𝜏 (u) = { u𝜏 , i fu > 0 u(𝜏 − 1) otherwise 2.5 spatial autoregressive model (sar) the sar model is a linear model with a spatial correlation of the dependent variables. the sar model is written as follows (anselin and anselin, 1988) : y = _wy + x 𝛽 +u , u ∼ n(0, 𝜎2i) (6) © 2023 the authors. page 323 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 where _ represents spatial autoregressive coefficient, which shows the magnitude of spatial dependence between regions, w denotes spatial weighting matrix of size n×n, and 𝛽 is quantile regression coefficient vector of size (k+1) ×1. parameter estimation of the sar model can be estimated using the maximum likelihood estimation (mle) method by assuming that the residual u is random variable from the normal distribution, n(0,𝜎2). parameter estimation for 𝛽 in the sar model is obtained as follows: 𝛽 = (x′x)−1x′(1−_w )y (7) while the estimation of parameter 𝜎2in the sar model is obtained as follows: �̄� 2 = 1 n ((i − _w )y −y 𝛽)′((i − _w )y − x 𝛽), (8) parameter estimation _ can be obtained using a numerical approach (anselin and anselin, 1988) . figure 3. spatial outliers in the sar model 2.6 spatial autoregressive quantile regression model (sarqr) the sarqr model is a model that combines spatial autoregressive models with quantile regression. the sarqr has the spatial autoregressive coefficient (_ ) and the regression vector ( 𝛽 ), which depend on certain quantile values (𝜏) (mcmillen, 2015; ver hoef et al., 2018). the development of sar modelling on the quantile 𝜏th is specifically defined as follows (lum and gelfand, 2012) : y = _𝜏wy + x 𝛽𝜏 +u. (9) figure 4. spatial outliers test based on sarqr model at 𝜏=0.45. the value of the spatial autoregressive coefficient in the sarqr model shows the magnitude of the spatial dependence between adjacent areas. the ivqr (instrumental variable quantile regression) method is used to estimate parameters in the sarqr model (yu et al., 2021) . the assumptions used in estimating the parameters in sarqr model are as follows (zhang et al., 2021a) : 1. p(ui≤0)=𝜏, for every i=1,2,...,n 2. supn≥1 max1≥i≥n e(ui) ≤ ` < ∞, 3. u ∼ n (0,_ 2i). getting the parameters _𝜏 and 𝛽𝜏 are done by minimizing equation (10) respect to each parameter. argmin e = 𝜌𝜏 ©­«yi − _𝜏 n∑︁ i=j 𝜔i jyj − x′i 𝛽𝜏 − g(xi , zi) ª®¬  (10) where g(xi, zi) is a linear function as instrumental variable quantile regression (ivqr). the steps for estimating the parameters based on ivqr in the sarqr model are as follows (su and yang, 2011; zhang et al., 2021b): 1. set a specific value for _ , and do the quantile regression modeling at 𝜏th quantile, which is defined as ( 𝛽𝜏 (_), �̄�𝜏(_)) = argmin𝛽 𝛾q𝜏 ( 𝛽 , _ , 𝛾) 2. to calculate the estimated value of the ivqr is done by minimizing the vector of the estimated variable instrument �̄�𝜏 (_ ) _̂𝜏 = argmin_ �̂�𝜏 (_)â(�̂�𝜏 (_))′ where â=a+op(1), a is a positive definite matrix. 3. the estimator 𝛽 is obtained in the following way. 𝛽𝜏 = 𝛽𝜏−1_̂𝜏−1 repeat the above steps for each quantile 𝜏. at each quantile 𝜏, different estimating parameters are obtained. © 2023 the authors. page 324 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 3. results and discussion table 1 and figure 1 present respectively the descriptive and box plot of data used in this study. figure 1 informs us that there are outliers on the population percentage (x1), grdp (x4) and oul (y). furthermore, the multicollinearity test among independent variables were carried out to find out whether there was a correlation between each independent variable. the results of the multicollinearity test are presented in table 2. each variable has vif value less than 5, meaning there is no multicollinearity problem between the independent variables. the spatial weighting matrix in this study uses the queen contiguity (side contact and corner points between regions). this study’s spatial units are districts/cities in west java province. the list of regencies/cities in the adjacent west java is presented in table 3. in this section, the empirical data regarding the open unemployment level in 26 regions in west java is employed to construct the oul model. the first step is to estimate the moran’s index coefficient values based on equation (2): i = n ∑n i=1 ∑n j=1 wi j(yi − ȳ)(yj − ȳ)∑n i=1 ∑n j=1 wi j ∑n j=1(yj − ȳ)2 = 0.5528 it is found that i value is positive, which means that adjacent areas have similar values and data patterns tend to be clustered. the next test is to estimate the moran’s index using equation (2) above. it is obtained that value of moran’s index is 4.1451 where it indicated that there is a spatial dependence between regions in west java province. furthermore, the lagrange multiplier test was carried out to determine the spatial dependence on the dependent variable, as written in equation (3). this study found that the lagrange multiplier value is 3.9572, which means that there is a spatial dependence on the dependent variable. additionally, the heteroscedasticity test is also determined in the hypothesis model using the breusch-pagan test. based on the data used in this study, the breusch-pagan’s value in this hypothesis model is 2.9538 (with p-value is 0.061). it indicates that the variances of open unemployment level among regions in east java are the same. the sar model was carried out because there is a spatial effect in the form of spatial dependence on the dependent variable, where the results of the parameter estimation of the sar model can be seen in table 4. based on table 4, it is found that not all independent variables have a significant influence on district/city oul in west java province. the independent variables that have significant effect on oul are the percentage of poor people (x2) and lfpr (x3), indicated by p-value for corresponding predictor are smaller than the significance level 𝛼=0.1. meanwhile, the percentage of the population (x1), grdp (x4) and % hdi (x5) have no a significant effect on oul. the purpose of this regression is to build the best model that can predict the dependent variable (oul), so the spatial autoregression model of oul in west java province obtained from data analysis is: �̂� =0.322wy + 13.041 + 0.143x1 + 0.295x2 − 0.302x3 + 0.005x4 + 0.142x5 based on above equation, it can be explained that: _̂ =0.322, means that the open unemployment level of each province has an effect of 0.322 times the average open unemployment level of each neighboring province. an increase of 1% in the poor population (x2) will increase the open unemployment level by 0.295, where other variables are considered constant. the proposed model also informed us that an increase of 1% in the labor force participation level or lfpr (x3), will decrease the open unemployment level by 0.302, where other variables are considered constant. it is only the significant variables can be interpreted, the non-significant variables give no meaning. spatial effect testing in spatial dependence and spatial diversity was conducted again on the sar model. this is done to check whether the sar model can handle spatial effects properly or not. in terms of spatial diversity, p-value = 0.8863 > 𝛼= 0.05 means that between regions have the same variance. in spatial dependence, p-value = 0.0155 < 𝛼 = 0.05 means that the sar model still contains the effect of spatial dependence on the dependent variable. furthermore, moran’s scatterplot is figured to detect spatial outliers in the sar model, as provided in figure 3. in this figure, it is found that there are five spatial outliers in the sar model, those are observations number 2, 3, 9, 17 and 23, denoted by star. outliers will affect the parameter estimation results and decrease model accuracy. therefore, the oul model obtained based on sar method could not be accepted. sarqr model is then applied to deal with spatial effects and data containing spatial outliers to obtain more acceptable model. sarqr modelling produces a model that may differ in each quantile. sarqr modelling uses the ivqr method as parameter estimation by minimizing the coefficients of the instrument variables for each quantile so that the optimal independent variable parameters and spatial autoregressive coefficients are obtained in the sarqr model. the results of parameter estimation for each quantile are presented in table 5. it can be seen in table 5 that percentage of the population (x1), percentage of poor population (x2), lfpr (x3), and grdp (x4) are significant in selected quantile. the spatial autoregressive coefficients on the sarqr model are varies among quantiles, some are positive, other are negative, and several are close to zero. the sarqr model which has a positive spatial autoregressive coefficient, indicates that the districts/cities in the adjacent west java province have a positive influence on the districts/cities in the west java province in that quantile. the comparison between sar and sarqr models based © 2023 the authors. page 325 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 table 1. descriptive statistics on data variable mean q1 median q3 % population (x1) 3.85 2.13 3.49 5.03 % poor population (x2) 8.40 6.53 8.27 10.39 lfpr (x3) 64.56 61.88 64.09 67.75 grdp (x4) 62.10 22.25 32.25 ipm % hdi (x5) 71.78 67.96 70.74 74.38 oul (y) 10.57 9.75 11.00 12.00 table 2. multicollinearity test results independent variable vif % population (x1) 1.76 % poor population (x2) 2.69 lfpr (x3) 1.08 grdp (x4) 1.69 % hdi (x5) 2.72 table 3. the neighboring regions in west java regions neighboring regions bogor suka bumi. cianjur. purwakarta. karawang. bekasi. sukabumi city. city of depok. and bekasi sukabumi bogor. cianjur. and sukabumi city, cianjur bogor. sukabumi. bandung. arrowroot purwakarta. west bandung cianjur. garut. sumedang. subang. west bandung. bandung. cimahi city garut cianjur. bandung. tasikmalaya. sumedang tasikmalaya garut. ciamis. majalengka. sumedang. tasikmalaya city ciamis tasikmalaya. kuningan. majalengka. tasikmalaya city. banjar kuningan ciamis. cirebon. majalengka cirebon kuningan. majalengka. indramayu. cirebon city majalengka tasikmalaya. ciamis. kuningan. cirebon. sumedang. indramayu sumedang bandung. garut. tasikmalaya. majalengka. indramayu. subang indramayu cirebon. majalengka. sumedang. subang subang bandung. sumedang. indramayu. karawang. purwakarta. west bandung, purwakarta bogor. cianjur. subang. karawang. west bandung karawang bogor. subang. purwakarta. bekasi bekasi bogor. karawang. bekasi city, west bandung, cianjur. bandung. subang. purwakarta. bandung. cimahi bogor city bogor sukabumi city sukabumi bandung city bandung. west bandung. cimahi city cirebon city cirebon bekasi city bogor. bekasi. depok depok city bogor. bekasi cimahi city bandung. west bandung. city of bandung tasikmalaya city tasikmalaya. ciamis banjar city ciamis © 2023 the authors. page 326 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 table 4. model estimation results with the sar model variable estimated mean standard error z-statistics p-value constant 13.0411 9.9793 1.3072 0.1912 % population (x1) 0.1432 0.1342 1.0654 0.2873 % poor population (x2) 0.2951* 0.1564 1.8853 0.0593 lfpr (x3) -0.3022* 0.0763 -3.9491 0.0000 grdp (x4) 0.0052 0.0053 0.8692 0.3850 % hdi (x5) 0.1421 0.0932 1.5332 0.1250 sar coefficient (_ ) 0.3222 0.1701 1.8882 0.0572 * significant at the significant level 𝛼=0.1,z𝛼/2= 1.645 table 5. estimated parameter based on sarqr quantile parameters (𝜏) constants x1 x2 x3 x4 x5 _ 𝜏 0.10 24.666 -0.294 -0.058 -0.363* 0.007 0.073 0.021 0.15 14.345 -0.249 0.164 -0.304* -0.000 0.126 0.023 0.20 14.832 -0.219 0.189 -0.305 -0.001 0.111 0.018* 0.25 -2.342 0.020 0.436 -0.157 0.009 0.139 0.015* 0.30 -2.342 0.019 0.436 -0.157 0.009 0.140 0.015* 0.35 5.601 0.125 0.410 -0.216 0.006 0.092 -0.019 0.40 11.052 0.263 0.389 -0.264 0.002 0.067 -0.001 0.45 14.659 0.197 0.426* -0.336* 0.005 0.104 -0.002* 0.50 14.916 0.147 0.429 -0.348* 0.006 0.119 0.000 0.55 12.145 0.123 0.487 -0.339* 0.006 0.145 -0.005 0.60 9.940 0.375* 0.415 -0.330* -0.001 0.187 0.005 0.65 13.055 0.316* 0.309 -0.288* -0.001 0.131 0.024 0.70 17.709 0.311* 0.269 -0.289* 0.001 0.067 -0.018* 0.75 11.128 0.357* 0.278 -0.233* -0.005 0.093 -0.018 0.80 -0.351 0.391* 0.325 -0.176 -0.009 0.187 -0.003 0.85 -2.357 0.385 0.262 -0.229 -0.016* 0.255 0.018* 0.90 -1.381 0.380 0.238 -0.236 -0.016* 0.252 0.018* 0.95 -1.381 0.380 0.238 -0.236 -0.017* 0.252 0.018* *significant at level 𝛼=0.1 © 2023 the authors. page 327 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 table 6. the comparison between sar and sarqr model. model spatial dependency test spatial diversity test aiclm value p-value bp value p-value sar 5.8601 0.0155 3.1674 0.0751 105.2200 sarqr 𝜏=0.10 0.0549 0.8146 1.8686 0.1716 71.6224 sarqr 𝜏=0.15 0.0052 0.9426 1.4958 0.2213 72.3596 sarqr 𝜏=0.20 0.0066 0.9353 1.5040 0.2146 69.7271 sarqr 𝜏=0.25 2.7343 0.0982 3.0631 0.0801 72.0653 sarqr 𝜏=0.30 3.6432 0.0563 3.0673 0.0799 72.3285 sarqr 𝜏=0.35 2.2484 0.1338 0.7179 0.3968 71.1260 sarqr 𝜏=0.40 3.1256 0.0771 0.5489 0.4588 75.6256 sarqr 𝜏=0.45 3.2947 0.0695 0.7238 0.3949 63.2113 sarqr 𝜏=0.50 2.7432 0.0977 0.8668 0.3518 72.1255 sarqr 𝜏=0.55 2.4893 0.1146 0.9020 0.3423 76.9123 sarqr 𝜏=0.60 2.9768 0.0845 0.7254 0.3944 77.1333 sarqr 𝜏=0.65 0.0300 0.8625 1.4136 0.2345 88.5306 sarqr 𝜏=0.70 2.4576 0.1170 1.3566 0.2411 91.0339 sarqr 𝜏=0.75 2.6164 0.1058 1.1538 0.2827 88.1333 sarqr 𝜏= 0.80 3.8364 0.0502 1.0257 0.3112 69.8960 sarqr 𝜏 = 0.85 1.8343 0.1756 1.0736 0.3001 77.7989 sarqr 𝜏 = 0.90 2.3478 0.1255 0.9457 0.3308 78.8910 sarqr 𝜏 = 0.95 2.3478 0.1255 0.9457 0.3308 78.8910 on the results of spatial dependency tests and spatial diversity test. the criteria for the best model is based on the smallest value of aic (akaike information criteria) (yasin et al., 2020) , provided in table 6. it can be informed in tabel 6 that all p-value for spatial dependency test and spatial diversity test are all more than 0.05. it indicated that in these sarqr model, there is no spatial dependency on the dependent variable for each quantile. in other words, the sarqr model can overcome the problem of spatial dependence on the dependent variable. furthermore, in the inter-regional spatial diversity test, both methods (sar and sarqr) have resulted in the homogenous variance of interregional for each model, indicated by all p-value being higher than 0.05. it means no longer problem with inter-regional spatial diversity. table 6 also informs us that model sarqr at all quantiles has a smaller value of aic than the sar model, with a model at 𝜏=0.45 having the smallest value of aic. the spatial outliers will be detected in this quantile, as the example. figure 4 shows that the sarqr quantile 0.45 model has no spatial outliers, meaning there is no longer an outlier problem in this sarqr model. the proposed model for estimating the open unemployment level is based on this sarqr model at 𝜏=0.45: ŷ = − 0.002wy + 14.659 − 0.197x1 + 0.426x2− 0.336x3 + 0.005x4 + 0.104x5 the proposed model at this 0.45 quantile informs us that: _̂ =0.002, means that the open unemployment level of each province has an effect of 0.002 times the average open unemployment level of each neighboring province. an increase of 1% in the poor population (x2) will increase the open unemployment level by 0.426, where other variables are considered constant. the proposed model also informed us that an increase of 1% in the labor force participation level or lfpr (x3), will decrease the open unemployment level by 0.336, where other variables are considered constant. 4. conclusion the comparison between the sar model and the sarqr model based on the aic value is the sarqr model is good at predicting oul in west java province. the sarqr model is also proven to deal with spatial effect problems such as spatial dependence and spatial diversity and is not easily affected by the presence of outliers. the sarqr model can provide model information for each selected quantile of the response distribution, while the sar model can only estimate the average response model. it is recommended for further research to use other parameter estimation methods such as gml (quasi maximum likelihood), gmm (generalized method of moments), and 2sls (two stage least square). the comparison study among those methods is also important. 5. acknowledgment this research was funded by drpm, the deputy for strengthening research and development of the ministry of research and technology/national research and innovation agency of © 2023 the authors. page 328 of 329 yanuar et. al. science and technology indonesia, 8 (2023) 321-329 indonesia, following contract number t/23/un.16.17/pt.01. 03/pdkn-kesehatan/2022. references anselin, l. and l. anselin (1988). the scope of spatial econometrics. spatial econometrics: methods and models, 3(4); 7–15 candraningtyas, c. p. and a. b. santosa (2022). open unemployment rate modeling in the province of jawa timur in 2019-2021 using data panel regression method: open unemployment rate modeling in the province of jawa timur in 2019-2021 using data panel regression method. jurnal forum analisis statistik (formasi), 2(2); 92–103 central, b. s. 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spatial effects quantile regression spatial autoregressive model (sar) spatial autoregressive quantile regression model (sarqr) results and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper effect of synthesis methods on properties of copper oxide doped titanium dioxide photocatalyst in dye photodegradation of rhodamine b cheng yee leong1, hao lin teh1, man ching chen1, siew ling lee1,2* 1department of chemistry, faculty of science, universiti teknologi malaysia, 81310 johor bahru, malaysia 2centre for sustainable nanomaterials, ibnu sina institute for scientific and industrial research, universiti teknologi malaysia, 81300 johor bahru, malaysia *corresponding author: lsling@utm.my abstract copperoxidemodifiedtitaniumdioxidephotocatalystshavebeenwidelyreportedfortheirexcellentperformanceinthewastewater treatment. however, there is lack of information on the effect of different synthesis methods towards the properties and catalytic activity of the photocatalyst. in this research, a series of copper oxide doped titanium dioxide (cu tio2) photocatalysts were synthesized via three different methods of sonochemical, impregnation and physical mixing. cu tio2 of varied molar ratios of cu dopant to tio2 tr595 (1:99, 2:98, 3:97 and 4:96) were prepared. comparison of physical-chemical properties and photocatalytic activity among the synthesized samples and unmodified tio2 tr595 were made. x-ray diffraction analysis depicted the formation of tio2 rutile phase in all samples. besides, diffuse reflectance uv-visible analysis proved that the synthesized samples were active undervisible lightregion. accordingtothetaucplotandphotoluminescencespectra, thebandgapenergiesandrecombinationrate of electron-hole pairs of cu tio2 samples decreased upon loading of cu. moreover, edx analysis confirmed the existence of ti and cu in all the samples. the photocatalytic efficiencies of the synthesized samples were discovered through photodegradation of rhodamineborganicdye under6hoursofvisible light irradiation. amongst, cu tio2 photocatalystssynthesizedviasonochemical method with molar ratio of 2:98 produced the highest photocatalytic activity of 65% which attributed to the lowest recombination rate of photogenerated charge carriers and availability of large number of reactive oxidative species. keywords copper oxide doped titanium dioxide, photocatalyst, sonochemical, impregnation, physical mixing, rhodamine b received: 16 september 2021, accepted: 3 december 2021 https://doi.org/10.26554/sti.2022.7.1.91-97 1. introduction titanium dioxide (tio2) and its composites have excellent chemical stability and corrosion-resistance ability with favour able mechanical performance. there are three phases in tio2 which are anatase, rutile, and brookite. the activation of tio2 happens under ultraviolet light due to its wide bandgap of 3.2 ev for photoactivity. in other words, tio2 has limited photocatalytic activity under visible light. apart from that, the high electron–hole pairs recombination rate of tio2 has reduced its quantum e�ciency (leong et al., 2021) . as a result, modi�cation of tio2 has been conducted using di�erent metals or metal oxides to broaden its absorption spectra to visible light region (koh et al., 2017; koh et al., 2020; ooi et al., 2020; ooi et al., 2016). properties of tio2 could be improved by doping of cu compounds due to their high conductivity and low toxicity (isa et al., 2020; sabran et al., 2019). more importantly, cu signi�cantly extends the light response of tio2 into the visible region in solar energy area and the existence of cu metal on tio2 could obviously in�uence the particle size as well as oxygen number or intermediate species on tio2 surface (zuas and budiman, 2013) . the suitable amount of the addition of cu dopant was able to cause electron trapping and suppress the electron-hole recombination, thus improving the photocatalytic degradation rates greatly compared with bare tio2 (neena et al., 2018) . besides, cu-doping into/onto tio2 decreased the band gap signi�cantly to increase the photoactivity rate in visible light region. as a result, the absorption capacity for aromatic organic pollutants enhanced drastically after the doping of cu to tio2. various methods have been applied for the synthesis of cu tio2 photocatalysts. sonochemical method could be conducted via an ultrasonic bath or by using a probe type ultrasonic homogenizer to obtain the desired e�ects from ultrasonication including homogenization, extraction, deagglomeration, dispersing, emulsi�cation and disintegration (sahrin et al., 2020) . on the other hand, impregnation method involved procedure https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.91-97&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.91-97 teh et. al. science and technology indonesia, 7 (2022) 91-97 whereby active precursor that contained within a certain volume of solution was contacted with the solid support, which then the mixture was dried to remove the imbibed solvent (deraz, 2018) . the impregnation method was considered a fast and inexpensive approach. more importantly, it allowed determination of con�guration, crystallography and morphology of tio2 �nal products to be controllable in advance (deraz, 2018) . physical mixing method is also known as mechanical mixing method. it is an alternate, simple and cost-e�ective synthesis method that enables formation of composites in better hybrid structures that would having chemical and mechanical advantageous properties for industrial production (megha et al., 2018) . the utilization of this method in cu tio2 photocatalyst synthesis for dye photodegradation aspect is yet to be known. in this work, di�erent synthesis methods of sonochemical, impregnation and physical mixing methods were applied to synthesize cu tio2 photocatalysts. the physicochemical properties and photocatalytic performance of the resulting photocatalysts were examined. the direct comparison would be important to understand the e�ect of the synthesis methods on the properties and photocatalytic performance of these titania-based catalysts. 2. experimental section 2.1 photocatalysts preparation a series of cuo doped tio2 photocatalysts were prepared via sonochemical method. for this purpose, appropriate amount of pure rutile tio2 tr595 powder (≥ 99.0 %) was used as starting precursor. the tio2 precursor was added into a beaker together with the presence of 2.5 ml propylene glycol (merck, ≥ 99.0 %) and 26.5 ml water. after that, the mixture was stirred for 5 minutes. sodium hydroxide (merck, ≥ 99.0 %) was then added dropwise to the mixture until about ph 8-9 of solution was obtained. again, the reaction mixture was stirred for another 5 minutes. next, appropriate amount of copper(ii) nitrate trihydrate (merck, ≥ 99.0 %) was added to the mixture and stirred for 15 minutes. the molar ratio of tio2 to cu dopant was set at 98:2. after that, the ultrasonication process was carried out for a duration of 15 minutes at 91w. eventually, the precipitate was dried in an oven to obtain the cuo doped tio2 powder. meanwhile, a solution of copper precursors was prepared for capillary impregnation method. this was done by dissolving copper(ii) nitrate trihydrate in 50 ml of distilled water. after that, the solution was stirred for 30 minutes at room temperature. subsequently, appropriate amount of pure rutile tio2 tr595 powder was added to the solution. it was noted that the molar ratio of tio2 to cu dopant was �xed at 98:2. the reaction mixture was then stirred for another 2 hours. at last, the sample obtained was dried in an oven. the physical mixing method was conducted with the direct application of copper(ii) nitrate trihydrate and pure rutile tio2 tr595 without any further treatment. the samples were mechanically mixed in a beaker for 2 hours. the molar ratio of tio2 to copper(ii) nitrate trihydrate was set as 98:2. after �nishing the mechanical mixing process using magnetic stirrer, the reaction mixture was dried in an oven. samples of di�erent tio2 to cu molar ratios of 99:1, 97:3 and 96:4 were also prepared via the three methods mentioned above. all the samples prepared were denoted at x cu:tio2, x = molar ratio of cu to tio2. 2.2 characterizations the crystalline phases and crystal structures of the samples were examined with the technique x-ray di�ractometry (xrd). bruker advance d8 was applied with cu kα irradiation (λ = 0.15406 nm, 40 kv, 40 ma) and the samples were scanned in the range 2θ = 2 – 80o with step size 0.05o/s to obtain the xrd patterns. uv-vis spectrometer (perkinelmer lambda 35) equipped with integration sphere (baso4 coated 76 mm) was applied to study the optical properties of the samples. appropriate amount of sample was placed on the sample holder and scanned at wavelength ranged from 200 to 800 nm to collect the spectrum. tauc plot was used to determine the band gap energy of the samples. it was plotted as (αhν)2 against hν, where α was the di�use re�ectance spectra absorbance, h was the planck constant and ν was the frequency of light. photoluminescence spectroscopy ( jasco, fg-8500) with an excitation of 310 nm was used to study the rate of electron-hole recombination of the samples. the morphology of the selected samples was con�rmed with field emission scanning electron microscopy (fesem). field emission scanning electron microscope (hitachi su8020) coupled with edx analyser was utilized to scan the samples in order to produce high quality images and to con�rm the elements present in the selected samples. 2.3 photocatalytic testing photocatalytic testing was conducted by using 50 ml 15 ppm rhodamine b and 0.05 g samples and irradiated under 15 w led light source for 6 hours. prior to reaction, adsorption was carried out to ensure the decreased concentration of rhodamine b was attributed solely to photodegradation. the photocatalytic performance of each synthesized cu tio2 sample was calculated according to the formula below: photodegradation e�ciency(%)= c0 −ct c0 x100% (1) where, c0 = concentration of rhodamine b before reaction (ppm), ct = concentration of rhodamine b after reaction (ppm) 3. results and discussion 3.1 structural properties figure 1 displays the xrd di�raction patterns of cu tio2 samples with varied molar ratios which were synthesized via © 2022 the authors. page 92 of 97 teh et. al. science and technology indonesia, 7 (2022) 91-97 figure 1. xrd patterns of tio2 and synthesized cu tio2 samples (1 to 4 mol% of cu in tio2) via (a) sonochemical method, (b) impregnation method and (c) physical mixing method; r = rutile phase di�erent methods. the xrd patterns were �tting well with the standard data of rutile tio2 which referenced from the joint committee on powder di�raction standard (jcpds card no. 21-1276). this could be due to the small amount of cu dopant in the prepared samples. with the doping of cu to the titania, it was noticed that either strong or weak peaks of the rutile phase still could be identi�ed easily as there were total 11 peaks originated from each cu tio2 synthesized sample. the di�raction peaks at 27.40°, 36.10°, 39.20°, 41.33°, 44.00°, 54.30°, 56.70°, 62.70°, 64.00°, 69.00° and 69.80°, corresponding to (110), (101), (200), (111), (210), (211), (220), (002), (310), (301), and (112) planes respectively, which denoted the tetragonal structure of titania rutile phase (phromma et al., 2020) . deviation of peak position was not observed because the ti4+ substitutional sites were replaced and occupied by cu2+ dopant ions instead of causing distortion of the lattice structure (raguram and rajni, 2019) . furthermore, the ionic radius of cu2+ (0.73 å) was similar to ti4+ ion (0.74 å) which allowed the entry of cu2+ ion to replace ti on tio2 (isa et al., 2020) . the crystallite size of the synthesized cu tio2 samples was calculated using scherrer equation at (1 1 0) plane and the results are listed in table 1. overall, the crystallite size of cu doped samples was smaller than that of tio2. upon modi�cation with addition of cu dopant, the crystallite size of samples decreased to 47.55 nm for cu tio2 with molar ratio 2:98 but slightly increased after more cu doping. the cu doping successfully reduced the crystallite size of tio2 by inhibiting the tio2 crystallite growth. apart from that, the increase in the cu doping ratio enabled the increase in peak intensity which enhanced the crystallinity of doped tio2 tr595. the statefigure 2. dr-uv-vis spectra of tio2 and the synthesized cu tio2 samples via (a) sonochemical method, (b) impregnation method and (c) physical mixing method in the range of 250 – 450 nm ment was in accordance with the slight increase in crystallite size obtained when the concentration ratio of cu dopant increased and surpassed the optimum level (molar ratio 2:98). similar results can be referred from another previous report that mentioned that the crystallite size of the samples increased slightly upon addition of cu (rajamannan et al., 2014) . in short, the smaller crystallite size of tio2 tr595 after doping with cu in optimum level could increase the surface area as well as the number of active sites which in turn enhanced the transfer rate of surface charge carrier in the photocatalytic activity (carrera-lópez and castillo-cervantes, 2012; ooi et al., 2020). 3.2 optical properties the optical absorption characteristics of the synthesized samples were performed by dr-uv-vis analysis. the optical re�ectance spectra of cu tio2 at di�erent molar ratios which © 2022 the authors. page 93 of 97 teh et. al. science and technology indonesia, 7 (2022) 91-97 table 1. crystallite size of tio2 and the synthesized cu tio2 samples methods synthesized sample crystallite size/nm tio2 tr595 53.89 sonochemical 1:99 cu tio2 50.52 2:98 cu tio2 47.55 3:97 cu tio2 50.52 4:96 cu tio2 53.89 impregnation 1:99 cu-tio2 50.52 2:98 cu tio2 47.55 3:97 cu tio2 50.52 4:96 cu tio2 50.52 physical mixing 1:99 cu tio2 53.89 2:98 cu tio2 47.55 3:97 cu tio2 50.52 4:96 cu tio2 50.53 synthesized via di�erent methods are depicted in figure 2 in the range of 250 – 450 nm. based on figure 2, there was a similar absorption peak at 345 nm for all the synthesized cu tio2 samples. generally, the dr-uv-vis spectra of typical tio2 has strong absorption where its peak ranging from 200 400 nm. a broad peak can be observed from range of 550 800 nm except for tio2. the broad absorption peak was due to the presence of cu+ or cu2+ ions which accompanied by the surface plasmon resonance e�ect (gondal et al., 2013) . the optical absorption properties were enhanced after cu doping which caused red shift to happen as the absorption spectra of tio2 were shifted towards longer wavelengths (biru et al., 2021) . this could be explained as the shifting of absorption band towards visible light region after the incorporation of cu into tio2 tr595. the doping of cu slightly decreased the band gap energy of tio2 (2.98 ev) to around 2.94 ev for cu tio2 with molar ratios 1:99, 2:98, 3:97 and 4:96. the results obtained were matched with a previous report that claimed the greater reduction in band gap energy of tio2 with increasing concentration of dopant which caused by the reason of cu-o interaction with covalent characteristic (mathew et al., 2018) . moreover, it can be deduced that the addition of cu dopant caused the reduction of band gap energy from uv light region to visible light region. the visible light absorption can be attributed to the replacement of ti4+ from tio2 lattice by cu 2+/cu+ and caused the formation of mid gap energy levels in the synthesized samples along with formation of oxygen vacancies, hence narrowing the band gap value (bharti et al., 2016) . 3.3 photoluminescence study figure 3 illustrates photoluminescence spectra of the selected samples at the excitation wavelength of 310 nm. the lower intensity of photoluminescence spectrum, the lower density of the recombination centres in a material, leading to low recombination rate of electron-hole pairs. as noticed from figure 3, cu tio2 with molar ratio 2:98 synthesized via sonochemical method has the lowest emission intensity while tio2 tr595 has the highest emission intensity. a reduction of 48.59% in emission intensity was observed in cu tio2 synthesized by sonochemical method as compared with tio2 tr595. this could be due to the improvement of charge separation by ultrasonication through generation of more hydroxyl radicals which thus reducing the electron-hole recombination rate (sivakumar et al., 2010) . a broad peak in spectrum was appeared for each cu tio2 sample which was similar as the peak location discovered in tio2 tr595. the broad peaks were located at the range around 500 to 650 nm with the peaks of cu tio2 were situated at approximately 550 nm. this was due to the occurrence of electrons self-trapping by octahedral shape of tio6 (alotaibi et al., 2020) . the results obtained were similar to another study using di�erent cu-doping concentrations with tio2 to get the photoluminescence emission spectra (alotaibi et al., 2020) . figure 3. photoluminescence spectra of (a) tio2 tr595, (b) 2:98 cu tio2 sonochemical, (c) 2:98 cu tio2 impregnation and (d) 2:98 cu tio2 physical mixing moreover, the addition of cu dopant decreased the photoluminescence intensity e�ciently as compared with pure tio2 tr595. it can be explained as e�ective inhibition of the photogenerated electron to be recombined from conduction band to valance band of tio2 (reda et al., 2020) . since cu2+ ions were well doped into tio2 structure, some undesired cu–cu interactions were acted as luminescent quencher to make the emission intensity to decline (raguram and rajni, 2019) . cu tio2 with molar ratio 2:98 synthesized via sonochemical method has the slowest electron-hole recombination speed which revealed its top e�ectiveness in the highest reduction in photoluminescence peak intensity. 3.4 morphology study figure 4 shows the fesem images of the selected sample of 2:98 cu tio2 synthesized via sonochemical method. as observed in figure 4 (a) and (b), it can be deduced that the © 2022 the authors. page 94 of 97 teh et. al. science and technology indonesia, 7 (2022) 91-97 cu doping did not change the morphology much although the cu2+ ions were incorporated into the tio2 matrix (raguram and rajni, 2019) . the size range of tio2 tr595 was between 130 nm and 250 nm. meanwhile, the size of cu tio2 sample observed from the fesem image was estimated in the range from 120 to 240 nm. figure 4. fesem images of (a) tio2 tr595, (b) 2:98 cu tio2 sonochemical and (c) edx spectrum of 2:98 cu tio2 sonochemical the size variation was possibly caused by the doping of cu into some tio2 surfaces which made the suppression of tio2 by grain boundaries resistivity (biru et al., 2021) . as a result, it was clearly seen that some cu tio2 particles were smaller than those did not covered by cu dopant. based on the edx spectrum in figure 4 (c), there was an obvious strong peak for element ti of cu tio2 with molar ratio 98:2 which located at 4.5 kev as well as some weak peaks witnessed at 0.4 and 5.0 kev. furthermore, the element o was found at peak 0.5 kev while the element cu was noticed peaks approximately at 1.0, 8.0 and 9.0 kev for the respective sample. there was no peak of nitrate found in the spectrum where the nitrate came from the precursor cu(no3) 2.3h2o. besides, there were three signi�cant compositions including 59.5 wt% of ti, 38.8 wt% of o and 1.7 wt% of cu that originated from the quantitative results of elements which made up total 100 wt%. 3.5 photocatalytic testing photodegradation of rhodamine b under visible light irradiation was conducted to evaluate the photocatalytic performance of the synthesized cu tio2 samples. the obtained absorbance at 553 nm was used to calculate the photodegradation e�ciency of the synthesized samples. as depicted in table 2, cu tio2 with molar ratios of 1:99, 2:98, 3:97 and 4:96 have higher photodegradation performances as compared to unmodi�ed tio2 tr595. the lowest photocatalytic activity of tio2 tr595 was due to its large band gap values (2.98 ev) as shown in the dr uv-vis analysis. as a result, the visible light uptake by tio2tr595 particles was very limited, leading to its low photocatalytic activity under visible light irradiation (reda et al., 2020) . therefore, the addition of cu transition metal could enhance the photocatalytic activity of tio2. it can be explained as cu dopant served as a trapping site for photogenerated electrons to increase the electron-hole pairs’ lifetime as well as raised the chance of reactions to produce reactive oxygen species (kerkez and boz, 2014) . in addition, the cu dopant also served as an intermediate level of visible light electron excitation for the electron movement from valence band to conduction band after getting su�cient energy from visible light (biru et al., 2021) . table 2. photodegradation e�ciency of tio2 and the synthesized samples methods samples photodegradation e�ciency (%) tio2 tr595 54 sonochemical 1:99 cu tio2 61 2:98 cu tio2 65 3:97 cu tio2 58 4:96 cu tio2 58 impregnation 1:99 cu tio2 61 2:98 cu tio2 63 3:97 cu tio2 58 4:96 cu tio2 57 physical mixing 1:99 cu tio2 60 2:98 cu tio2 62 3:97 cu tio2 58 4:96 cu tio2 58 noticeably, there was subsequent increase in the photocatalytic activity when the amount of cu dopant increased from 1 to 2 molar ratio in the samples. interestingly, all cu tio2 samples with molar ratio of 2:98 showed the best photocatalytic activity of 65%, 63% and 62% in their series which synthesized via sonochemical, impregnation and physical mixing methods, respectively. this could be attributed to the smaller crystallite size and particle size of these samples as evidenced by the xrd and fesem analyses. it is widely accepted that smaller particle size is crucial for a larger surface area of the sample in order to increase the number of active sites, thus leading to the highest photocatalytic e�ciency. the current �ndings suggested that more reactive oxygen species such as oh radicals would be produced through the sonochemical synthesis method. it is expected that the ultrasonication process has increased e�ciency of charge separation and decreased the speed of electron-hole © 2022 the authors. page 95 of 97 teh et. al. science and technology indonesia, 7 (2022) 91-97 recombination (sivakumar et al., 2010) . when the molar ratio of cu increased above the optimum level (2 mol%), the continuous addition of cu did not bene�cial to the photocatalytic activity of tio2. the excess amount of cu2+ ions were unable to di�use into lattice structure of tio2, but only deposited on the surface area (biru et al., 2021) . this led to the blockage of active sites of tio2 which hindered the penetration of light reaching on tio2 surface (riaz et al., 2014) . the inhibition of photocatalytic activity happened since the number of photogenerated electrons and holes also declined. apart from that, another report stated that when the metal loading kept on increasing, it caused the occurrence of metal particles to agglomerate and hence reduced the photocatalytic performance of the photocatalyst (koh et al., 2017) . thus, the reasons above explained the decrease in photodegradation percentages for cu tio2 of molar ratios 3:97 and 4:96. in short, the modi�cation of cu dopant on tio2 was able to enhance to photocatalytic activity but if only doped with the optimum amount without excess. 4. conclusions cuo doped tio2 photocatalysts of di�erent molar ratios were successfully synthesized via three di�erent methods including sonochemical, impregnation and physical mixing methods. the xrd analysis proved the presence of rutile tio2 in the samples and smaller crystallite size of cu tio2 were obtained due to broadening e�ect after the incorporation of cu into tio2 matrix. reduction of band gap energy with cu dopants were observed under tauc plots, lower recombination of electron hole pairs was discovered under photoluminescence analysis and reduction of particle size of cu tio2 were justi�ed via fesem analysis. the formation of new energy level in cu tio2 allowed these cuo doped tio2 samples to be active in visible region. among all the samples, cu tio2 of molar ratio of 2:98 synthesized via sonochemical method achieved the best photocatalytic performance of 65% photodegradation of rhodamine b under visible light irradiation. it has been demonstrated that the high photodegradation e�ciency was due to the high crystallinity, smaller particle size with larger surface area of the sample, lower band gap energy as well as lower recombination rate of electron-hole pairs. 5. acknowledgement the authors are grateful to the ministry of higher education (mohe), malaysia and universiti teknologi malaysia for the 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26–33 © 2022 the authors. page 97 of 97 introduction experimental section photocatalysts preparation characterizations photocatalytic testing results and discussion structural properties optical properties photoluminescence study morphology study photocatalytic testing conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper okra mucilage extract as a co-surfactant increased the curcumin nanoemulsion stability and encapsulation efficiency el fajriyah auliya putri1, ellya indahyanti1, diah mardiana1, maria lucia a.d lestari2, zubaidah ningsih1* 1department of chemistry, faculty of mathematics and natural science, universitas brawijaya, jawa timur, 65145, indonesia2department of pharmaceuticals science, faculty of pharmacy, universitas airlangga, jawa timur, 60115, indonesia *corresponding author: zubaidah@ub.ac.id abstractcurcumin has various bio-functional properties; however, curcumin poor bioavailability reduces its efficacy. nanoemulsion deliverysystem is an alternative method improving curcumin bioavailability in which surfactant and oil used, play an important role indetermining nanoemulsion properties. several studies on curcumin nanoemulsions apply synthetic surfactants which can be harmfulif they are added excessively. this study aims to use a natural emulsifying agent, namely okra mucilage extract (ome), and determineits effectiveness as co-surfactant. ome is safe to use as an emulsifying agent because it is natural, harmless, safe, biodegradable andeco-friendly. liquid-liquid and microwave extraction methods were used to obtain ome which was further identified using fouriertransfer infrared spectroscopy (ftir). meanwhile, sonication method was used to produce curcumin nano-emulsion (curn). theparticle size and polydispersity index of curcumin nano-emulsion were measured using particle size analyzer (psa) with dynamiclight scattering (dls) technique, while the morphology of the nanoemulsion was observed using a digital imaging microscope andconfocal laser scanning microscope (clsm). the results showed that the addition of 0.0160 g ome at a ratio of 1:5 (ome: tween80) in the preparation of 5 ml of curn was able to reduce the particle size and polydispersity index from 740.80 ± 9.70 nm to289.20 ± 2.23 and 0.340 ± 0.005 to 0.165 ± 0.008 respectively. ome increased the encapsulation efficiency from 77.93 ± 6.59%to 87.17 ± 1.12% which was confirmed by the augmentation of the fluorescence intensity of curcumin from 192.82 to 388.55. theaddition of ome also maintained the stability of the curn up to 14 days of storage at 4°c. keywordscurcumin, okra mucilage extract, nanoemulsion received: 24 january 2023, accepted: 3 july 2023 https://doi.org/10.26554/sti.2023.8.3.509-515 1. introduction turmeric (curcumalongal.) is one of the most common medicinal plants in indonesia. turmeric contains an active compound, curcumin, which has various bio-functional properties to prevent various diseases including diabetes. in addition, curcumin also has biofunctional properties such as anti-tumor, antioxidant, anti-inflammatory and anti-diabetic (den hartogh et al., 2019; gabr et al., 2022; jakubczyk et al., 2020; kunnumakkara et al., 2017). however, curcumin has some disadvantages like poor bio-distribution, metabolism, and bioavailability. based on several clinical trials, it is shown that curcumin is only detected in small amounts or even not being absorbed within cells (dei cas and ghidoni, 2019; md saari et al., 2020). curcumin is a lipophilic active substance and has poor polarity and dissolution rate in water which inhibits the distribution of curcumin to body organs (toden and goel, 2017) . thus, encapsulated curcumin in nanoemulsion system is being developed to increase the efficiency of curcumin as a drug (kumar et al., 2016) . jannah, et al. developed curcumin nanoemulsion with a high encapsulation efficiency up to 81% in the system added with lecithin surfactant (jannah et al., 2021) . it also increased up to 90.56 ± 0.47% in the curcumin nanoemulsion system containing medium chain triglyceride (sari et al., 2015) . nanoemulsions are colloidal systems in the submicron size range that can act as carriers of drug molecules with an average size ranges from 10 to 1000 nm (jaiswal et al., 2015) . nanoemulsions deliver bioactive compound to the target site which requires a stable system during its circulation in the body. the encapsulation and the release of bioactive compounds may be influenced by the type of emulsifiers, structural and compositional properties of the nanoemulsion systems (chuacharoen et al., 2019) . the main composition of nanoemulsion consists of bioactive substances, oil, water and surfactants. the type of https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.509-515&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.509-515 putri et. al. science and technology indonesia, 8 (2023) 509-515 oil and surfactant used are adjusted according to the type of bioactive substance to be encapsulated. furthermore, the composition ratio is also a determining factor for the physiochemical properties and stability of the nanoemulsions (chuacharoen et al., 2019) . pinheiro et al. (2013) compared the use of tween 20, sodium dodecyl sulphate (sds) and dodecyltrimethylammonium bromide (dtab) surfactants in the manufacturing of curcumin nanoemulsions. the results show that different types of surfactants affect the stability and bioavailability of curcumin nanoemulsions in the body system (e.g. digestive and intestinal). several studies of curcumin nanoemulsion highlighted the use of a combination of synthetic and natural surfactants. sari et al. (2015) developed curcumin nanoemulsions stabilized by tween 80 (0.5-2%) and wpc-70 (0-1%), the most stable curcumin nanoemulsion was obtained with 2% tween 80 and 0.5% wpc-70. artiga-artigas et al. (2018) compared the use of three types of surfactants, tween 20, lecithin, and sucrose palmitate. the results showed that curcumin nanoemulsions containing tween 20 showed the highest encapsulation efficiency values. nowadays, natural surfactants or emulsifying agents, which can be obtained from natural ingredients, such as hydrocolloids, have been developed. hydrocolloids are components of longchain polymers (including polysaccharides and proteins) that have gel-forming properties when dispersed in water. hydrocolloids come from plants, animals, microbes, or components that generally contain hydroxyl groups. based on their characteristics, hydrocolloids have been developed into emulsifying, thickening, and stabilizing agents (herawati, 2018; saha and bhattacharya, 2010). okra (abelmoschus esculentus l.) extract, also known as a lady finger or gumbo, produces viscous mucilage in the form of hydrocolloid that contains polysaccharides and protein substances potential to be used as an emulsifier (lousinian et al., 2017; ritzoulis, 2017). natural mucilage such as okra fruit mucilage extract tends to be safe to use as an emulsifying agent because it is natural, harmless, safe, biodegradable, and eco-friendly (zaharuddin et al., 2014) . noorlaila et al. (2015) studied the properties and characteristics of okra mucilage extract which is used as an emulsifier in coconut milk emulsion and showed that okra mucilage extract was a potential emulsifier. in addition, okra mucilage extract was also a potential drug delivery control agent. pal (2020) encapsulated curcumin, thymoquinone, and piperine in a nanoparticle system using okra mucilage extract. the results showed that this system had a promising effect on inhibiting the growth of bacteria and cancer cells (pal, 2020) . apart from being used as an emulsifier, several studies have been conducted to find out the benefits of okra mucilage extract as an anti-bacterial, anti-diabetic, anti-cancer, and antioxidant (alba et al., 2013; dantas et al., 2021; uddin zim et al., 2021). the combination of two active substances, i.e. curcumin and okra mucilage extracts, is expected to give a synergistic effect as a herbal medicine. thus, modifying curcumin nanoemulsion using okra mucilage extract as co-surfactant is expected to increase nanoemulsion stability and bioavailability as well as the anti-diabetic effect of the two active ingredients. this research aims to develop curn system using ome as a co-surfactant in combination with tween 80 at several concentrations. the observed characteristics of curn were morphology, particle size, polydispersity index, encapsulation efficiency and stability. 2. experimental section 2.1 materials and tools materials used in this research are okra fruit, curcumin powder 95% (pharmaceutical grade, health-ingredients, china) which is used without further purification, tween 80 (pharmaceutical grade j0203/20, pt brataco, indonesia), soybean oil (food grade, mamasuka, jinyuone co., ltd, korea), methanol (a1056, pro analysis, smart lab, indonesia), acetone (technical grade), ethanol 96% (technical grade), and distilled water. the tools used in this research are delsatm nano c particle analyzer (beckman coulter, usa), stereo digital camera microscope (olympus bx-51), ultrasonic cleaner brand skymen cleaning equipment (shenzen co ltd 40 khz), confocal laser scanning microscope (cslm) olympus fv1000, magnetic stirers me hei-tec 145 (heidolph instruments gmbh & co.kg, germany), ftir irspirit-t a22415801432 (shimadzu corporation), uv-vis spectrophotometer 1601 220 v (shimadzu corporation), microwave 250w (sharp, indonesia), and imagej software 1.44 version (bethesda, maryland, usa). 2.2 methods 2.2.1 okra mucilage extraction okra fruit was cut into small pieces and the seeds were removed from the fruit. okra fruit was soaked in distilled water at 70°c for 4 hours with a ratio of okra fruit to distilled water of 1:5 followed with heating in microwave (250 w) for 2 minutes. ome was then separated using a filter cloth. following the filtering, ethanol was added (using ratio of ethanol: extract 1:1) to isolate the mucilage which was then stored in the refrigerator for 5 days until a complete isolation was achieved. the precipitation as the result of isolation process was then filtered and rinsed with acetone. the precipitate obtained was dried in the oven at 60°c for 24 hours. the dried precipitate was stored in a desiccator and then characterized using ftir instrument. 2.2.2 curcumin nanoemulsion preparation curn with ome was prepared by mixing the aqueous phase and the oil phase. the aqueous phase was prepared by dissolving ome and tween 80 in distilled water under continuous stirring for 24 hours at a speed of 200 rpm. the amount of ome and tween 80 added were varied (table 1). the oil phase was prepared by mixing 0.0250 g of curcumin with 200 `l of soybean-oil under continuous stirring for 2 hours at a speed of 200 rpm. the aqueous phase was added into the oil phase and then stirred for 15 minutes. vials containing a mixture of the aqueous and oil phase were then sonicated using a sonicator bath with a frequency of 40 khz for one 1 hour. for curn without ome, the procedure applied was identical, © 2023 the authors. page 510 of 515 putri et. al. science and technology indonesia, 8 (2023) 509-515 nonetheless, there was no addition of ome in the aqueous phase. 2.2.3 particle size and polydispersity index measurement the particle size and polydispersity index of curcumin nanoemulsions were analyzed using delsatm nano c particle analyzer based on dynamic light scattering technique. 2.2.4 curcumin nanoemulsion morphology the morphology of the curn were observed using a clsm with a magnification of 400. auto-fluorescence images were obtained using an excitation wavelength of 488 nm and an emission wavelength of 500 nm. curcumin has fluorescence properties; this is due to the presence of two phenol groups which are conjugated with double bonds. based on curcumin’s fluorescence intensity we can predict curcumin concentration (karimi et al., 2020) . 2.2.5 encapsulation efficiency determination concentration of curcumin encapsulated was measured based on the curcumin absorbance using uv-vis spectrophotometer at 420 nm wavelength. sample was diluted followed with centrifugation at 3500 rpm for 45 minutes. then, 5 ml of the filtrate was taken and used for subsequent analysis to determine the amount of free curcumin using the uv-vis method. the remaining filtrate was then diluted with methanol in a ratio of 1:1 and sonicated in a sonicator bath for 5 minutes to break the nanoemulsion system. free curcumin and total curcumin were measured for their absorbance using a uv-vis spectrophotometer. the amount of curcumin is calculated based on the absorbance value. encapsulation efficiency was then determined using the following formula. %ee = total curcumin-free curcumin total curcumin × 100% (1) 2.2.6 stability of curcumin nanoemulsion the morphology of the curn were observed by storing the samples at 4°c for 14 days. the samples were then observed using a digital imaging microscope on day 7 and 14 to see morphological changes caused by destabilization of the nanoemulsions. the photos obtained from the microscope were analyzed using imagej software to predict the average particle size and particle size uniformity based on the calculated standard deviation. 3. results and discussion 3.1 okra mucilage extract the resultant ome was in the form of thin reddish-brown flakes and the yield value was 0.9%. according to lim et al. (2015) , red color indicates the presence of tannin compounds. the ome was then identified using ftir instrument to characterize functional groups. ftir spectra (figure 1) displayed an absorption at a wavelength of 3369 cm−1 which indicated the presence of an o-h group as the main functional group figure 1. ftir spectra of ome from our research of the ome. the o-h group represents the hydrophilic characteristics in the polysaccharide while the moderate peak at 2935 cm−1 indicates the presence of c-h stretch in galactose and rhamnose. a small peak at 1719 cm−1 indicates the presence of c=o stretch which is a constituent of galacturonic acid. then the medium peak of 1409 cm−1 indicates the presence of bending vibration o-h bonds which are constituents of galacturonic acid. peak at 1200-1000 cm−1 indicates the co group contained in the aromatic compounds of galactose, rhamnose, and galacturonic acid. there are also amino acid functional groups identified, indicated by the presence of nh group overlap with o-h at 3369 cm−1 and a c-n stretch group at a sharp peak at 1068 cm−1. the identified functional groups signify that ome was also composed of hydrophilic and hydrophobic amino acids which contributed to the properties of ome as an emulsifying agent (arjunan, 2021; lim et al., 2015). compared to the result of lim et al. (2015) shown in table 2, our results are similar which substantiates that the extraction process yielded the targeted compounds. 3.2 particle size and polydispersity index particle size is one of the important parameters in drug delivery systems. particle size affects the drug dissolution rate where this dissolution rate depends on the surface area of the interface (sandri et al., 2014) . the measurement of nanoemulsion particle size show some changes along with the addition of ome (figure 2). particle size either decreased or increased at a certain concentration of ome. curn-0 has a particle size of 740.80 nm. the addition of ome as a co-surfactant as much as 0.0160 g (curn-1); 0.0250 g (curn-2) and 0.0500 g (curn-3) in the preparation of 5 ml of curn reduced particle size to 289.20 nm; 392.70 nm and 547.80 nm respectively. however, further addition of ome significantly increased the particle size to 1430.5 nm (curn-4) without further augmentation in the curn-5 (1338.1 nm). these results indicated that ome was able to reduce the particle size at a certain con© 2023 the authors. page 511 of 515 putri et. al. science and technology indonesia, 8 (2023) 509-515 table 1. composition of curcumin nanoemulsions sample code curcumin (g) soybean oil (µl) okra mucilage extract (g) tween 80 (g) aquadest (ml) curn-0 0.0250 200 0.0000 0.1000 4.7000 curn-1 (1:5) 0.0250 200 0.0167 0.0835 4.7000 curn-2 (1:3) 0.0250 200 0.0250 0.0750 4.7000 curn-3 (1:1) 0.0250 200 0.0500 0.0500 4.7000 curn-4 (3:1) 0.0250 200 0.0750 0.0250 4.7000 curn-5 (5:1) 0.0250 200 0.0750 0.0167 4.7000 table 2. comparison of the ftir functional groups functional group wavenumber (cm−1) based on the research the result of lim et al. (2015) o-h and n-h 3369 3413.3 c-h stretch 2935 2925.8 c=o stretch 1719 1722.3 o-h bend 1409 1409.9 c-n stretch 1068 1072.3 centration. further addition of ome affected inversely to the particle size; it was enlarged. similar to the particle size, the polydispersity index measurement also exhibited some changes as ome was added in the nanoemulsion system. polydispersity index, with the value varies from 0.1 to 1, describes the degree of uniformity of the particle size distribution. a value of less than 0.1 indicates that the particle has good size uniformity in colloidal suspensions while a value close to 1 signifies that the particle size uniformity decreases (subositi and wahyono, 2019) . all of our samples had polydispersity index values less than 0.5 which indicated that our system have relatively homogenous particle size distribution (evan et al., 2011) . figure 2 shows the changes of polydispersity index in each ome concentration. with no ome addition, the polydispersity index of the nanoemulsion was 0.340. the index went down to 0.165; 0.247; and 0.245 when the nanoemulsions were prepared with 0.0167; 0.0250 and 0.0500 g of ome, a small polydispersity index indicates that the nanoemulsion has better size uniformity. on the contrary, the polydispersity index increased to 0.391 and 0.476 at ome addition of 0.0750 to 0.0835 g, respectively. both indices exceeded that of nanoemulsion without ome addition, which implied the decrease of particle size uniformity. from particle size and polydispersity index measurement, our results confirmed that the effect of ome could be divided into 2 regions. in the first region, ome reduced particle size as well as increased the system uniformity. on the other hand, in second region, ome increased particle size and reduced system uniformity. 3.3 curcumin nanoemulsion morphology observation of the morphology of the curn was carried out using a clsm with a magnification of 400. curcumin was figure 2. particle size and polydispersity index of curn with different mass of ome addition shown as the bright green color in the image (figure 3). based on the 3d visualization, droplets of emulsion in a spherical shape were formed in curn-0 dan curn-1 systems, nonetheless, curcumin was more concentrated inside the droplet of the sample with added ome. the observed intensity in sample without ome as co-surfactant was 192.82 au the intensity of sample with added ome increased to 388.55 au. this signifies that ome enhanced the encapsulation of curcumin in the droplets and affected the morphology of the droplets. 3.4 encapsulation efficiency of curcumin nanoemulsions encapsulation efficiency represents the amount of curcumin trapped in the emulsion system. encapsulation efficiency is an important parameter to consider when evaluating the success of a nanoemulsion in drug delivery system (hudiyanti et al., © 2023 the authors. page 512 of 515 putri et. al. science and technology indonesia, 8 (2023) 509-515 figure 3. the clsm images of curn-0 (above) and curn-1 (below). curn-0 is a curn without the addition of ome and curn-1 is a curn with the addition of ome which has the smallest particle size. the brightness in the images was caused by the auto-fluorescence of curcumin (488 nm excitation). note that the dimension of the droplets was larger for the sake of image clarity. the scale bar is equal to 50 µm 2022) . in this study, the encapsulation efficiency of curn is measured on curn-0 and curn-1 (table 3). table 3 shows that the addition of okra mucilage extract as co-surfactant increases the encapsulation efficiency of curcumin. the use of both tween 80 and ome increased encapsulation efficiency by 10%. this augmentation was confirmed by the increase of curcumin intensity inside the droplets as shown in figure 3 from these results it can be seen that the combination of two types of surfactants could increase the amount of curcumin trapped in the nanoemulsion system (marin et al., 2016) . 3.5 stability of curcumin nanoemulsions in this study, stability observations were made on nanoemulsions stored at 4°c on day 7 and 14 (chuacharoen et al., 2019) . stability is determined from the changes in particle size and its diversity. unstable system shows a drastic change of particle size and uniformity during storage due to particle coalescence to form larger and irregular particle size (zhang and mcclements, 2018) . figure 4 shows the increase of predicted average particle size as a function of storage time both in the system with and without ome. linear regression was applied to determine the slopes of the curves which indicated the rate figure 4. predicted average particle size as a function of storage time of curn-0 and curn-1. curn-0 is a curn without the addition of ome and curn-1 is a curn with the addition of ome which has the smallest particle size figure 5. illustration scheme of curn based on the research results of particle size increase. the higher the value of the slope, the particle size increases faster which signifies the instability of the system. based on the data obtained in figure 4, it can be seen that the slope of curn system without ome was three times higher than that of the system with added ome. this tells us that ome increased system stability. fundamentally, nanoemulsion systems are thermodynamically unstable. this is due to the lower free energy required to separate the oil and water phases when compared to the energy for the emulsification process, thus, nanoemulsion stability can change during certain storage time due to various mechanisms (aswathanarayan and vittal, 2019) . temperature can affect the stability of nanoemulsions by changing the physical properties in the oil and water phases of the emulsion systems. at high temperatures, the viscosity of the nanoemulsions decrease and cause damage to the interface layer and it can cause coalescence (harun et al., 2018; liu et al., 2019). ome had the potential ability to stabilize the drug delivery system, increasing the encapsulation of active compounds in the drug delivery system (harun et al., 2018) . polysaccharides can adsorb at the oil-water interface and reduce the interfacial tension, thus, able to form emulsion droplets that are more stable in protecting the lipophilic active substances (shao et al., 2020) . an illustrative schematic of the nanoemulsion from © 2023 the authors. page 513 of 515 putri et. al. science and technology indonesia, 8 (2023) 509-515 table 3. the encapsulation efficiency of curcumin nanoemulsions sample curcumin (g) okra mucilage extract (g) tween 80 (g) %encapsulation efficiency curn-0 0.0250 0.0000 0.1000 77.93 ± 6.59*% curn-1 0.0250 0.0167 0.0835 87.17 ± 1.12*% *standard deviation value of three data the research results is exhibited in figure 5. in the figure, the hydrophobic group of tween-80 binds to oil and its hydrophilic group binds to water so that it can form a nanoemulsion system that encapsulates curcumin. we believe with the addition of ome, which is adsorbed onto the surface of the oil and water droplets, this ome together with tween-80 might increase and maintain the stability of the nanoemulsion by lowering the oil-water surface tension and increase the viscosity of the nanoemulsion so that it can prevent droplet coalescence. whereas the increasing particle size and decreasing system uniformity could be due to the binding of ome molecules, which are situated at the surface of the droplets, with each other to form a bridge that facilitates the incorporation of particles (flocculation) as shown in the illustration on the right in figure 5. hence, it increased the particle size and made the nanoemulsion unstable (shao et al., 2020) . 4. conclusion ome in our study can reduce the particle size and polydispersity index of curn at certain concentrations. at our best observation, the use of 0.016 g of ome (at ome to tween 80 ratio of 1:5) in the preparation of 5 ml of curn decreased the particle size and polydispersity index of curcumin nanoemulsion from 740.80 to 289.20 nm, and the polydispersity index value from 0.340 to 0.165. the addition of ome increased the fluorescence intensity of trapped curcumin from 192.82 to 388.55 au. this result was confirmed by an increase of encapsulation efficiency from 77.93 ± 6.59 to 87.17 ± 1.12% as observed using uv-vis spectrophotometer. furthermore, ome maintained the stability of the curn for up to 14 days at 4°c. natural emulsifiers, e.g. okra mucilage extract, can be used as an option to reduce the use of synthetic surfactants and to improve the quality of nanoemulsion in drug delivery systems. 5. acknowledgment we gratefully acknowledge the generous support from prof. andrew h.a. clayton, swinburne university of technology australia. references alba, k., c. ritzoulis, n. georgiadis, and v. kontogiorgos (2013). okra extracts as emulsifiers for acidic emulsions. food research international, 54(2); 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(2014). the use of hibiscus esculentus (okra) gum in sustaining the release of propranolol hydrochloride in a solid oral dosage form. biomed research international, 2014 zhang, z. and d. j. mcclements (2018). overview of nanoemulsion properties: stability, rheology, and appearance. nanoemulsions; 21–49 © 2023 the authors. page 515 of 515 introduction experimental section materials and tools methods okra mucilage extraction curcumin nanoemulsion preparation particle size and polydispersity index measurement curcumin nanoemulsion morphology encapsulation efficiency determination stability of curcumin nanoemulsion results and discussion okra mucilage extract particle size and polydispersity index curcumin nanoemulsion morphology encapsulation efficiency of curcumin nanoemulsions stability of curcumin nanoemulsions conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper subclasses of analytic functions with negative coefficients involving q-derivative operator andy liew pik hern1, aini janteng1*, rashidah omar2 1faculty of science and natural resources, universiti malaysia sabah, kota kinabalu, 88400, malaysia2faculty of computer and mathematical sciences, universiti teknologi mara cawangan sabah, kota kinabalu, 88997, malaysia *corresponding author: aini-jg@ums.edu.my abstractlet a denote the class of functions f which are analytic in the open unit disku . the subclass of a consisting of univalent functionsis denoted by m. in this paper, we also consider a subclass of m which is denoted byv , consisting of functions with negativecoefficients. in addition, this paper also studies the q-derivative operator. by combining the ideas, this paper introduced threesubclasses of a with negative coefficients involving q-derivative. furthermore, the coefficient estimates, growth results and extremepoints were obtained for all of these classes. keywordsanalytic, univalent, q-derivative operator received: 15 march 2022, accepted: 23 june 2022 https://doi.org/10.26554/sti.2022.7.3.327-332 1. introduction we denote a as the class of functions which has a maclaurin series expansion of the form f (𝛿) = 𝛿 + ∞∑︁ 𝜏=2 a𝜏 𝛿 𝜏. (1) the function f is analytic in the open unit disku = {𝛿 ∈ ℂ: |𝛿 |<1}. while we use m to represent the subclass of a and it is consisting of univalent functions. in recent times, there are quite a number of researchers have studied dierent subclasses of a whichassociatedwithq-derivative (seebreazandcotîrlă,2021; ibrahim, 2020; jabeen et al., 2022; janteng et al., 2020; khan et al., 2022; karahuseyin et al., 2017; murugusundaramoorthy et al., 2015; najafzadeh, 2021; oshah and darus, 2015; rashid and juma, 2022; shilpa, 2022). from (jackson, 1909; aral et al., 2013), we have the qderivative of a function f ∈ a which given by (1) with 0 < q < 1 as dq( f (𝛿)) = f (q𝛿) − f (𝛿) (q − 1)𝛿 , q ≠ 1, 𝛿 ≠ 0, (2) dq( f (0)) = f ′(0). from (2), we can get dq( f (𝛿)) = 1 + ∞∑︁ 𝜏=2 [𝜏]qa𝜏 𝛿𝜏−1, where [𝜏]q = 1−q𝜏 1−q . as q → 1, [𝜏]q → 𝜏. for a function j(𝛿) = 2𝛿𝜏, dq( j(𝛿)) = dq(2𝛿𝜏) = 2 ( 1 − q𝜏 1 − q ) (𝛿𝜏−1) = 2[𝜏]q𝛿𝜏−1 lim q→1 ( dq( j(𝛿)) ) = lim q→1 ( 2[𝜏]q𝛿𝜏−1 ) = 2𝜏𝛿𝜏−1 = j′(𝛿) where j′ is the ordinary derivative. furthermore, we denotev as a class with negative coecients and a subclass of m, consisting of the following functions f (𝛿) = 𝛿 − ∞∑︁ 𝜏=2 a𝜏 𝛿 𝜏 (3) where a𝜏 ≥ 0. for f ∈ v , there are some signicant researchers for example in (halim et al., 2005), the authors studied the class m∗sv ([ , 𝜗) consistingofstarlikefunctionswithrespect to (w.r.t) symmetric points. besides, there are various studies for example in (al-abbadi and darus, 2010; al shaqsi and darus, https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.327-332&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.327-332 hern et. al. science and technology indonesia, 7 (2022) 327-332 2007; atshan and ghawi, 2012; bucur and breaz, 2020; choo and janteng, 2013; halim et al., 2006; janteng and halim, 2009; najafzadeh and salleh, 2022; oluwayemi et al., 2022; porwal et al., 2022). in this paper, by considering functions f ∈ v and q-derivative operator, we introduce the classes m∗s,qv ([ , 𝜗), m ∗ c,qv ([ , 𝜗) andm∗sc,qv ([ , 𝜗). the coecient estimates, growth results, and extreme points are obtained for these classes. first, we give the denitions for the 3 classes. we note that as q → 1, we obtain the classes which were introduced by (halim et al., 2005). denition 1. a function f ∈ m∗s,qv ([ , 𝜗) if and only if it satises ���� 𝛿dq f (𝛿)f (𝛿) − f (−𝛿) − 1 ���� < 𝜗 ���� [𝛿dq f (𝛿)f (𝛿) − f (−𝛿) + 1 ���� for 0 ≤ [ < 1, 0 < 𝜗 < 1, 0 ≤ 2(1−𝜗)1+[𝜗 < 1 and 𝛿 ∈ u. denition 2. a function f ∈ m∗c,qv ([ , 𝜗) if and only if it satises ����� 𝛿dq f (𝛿)f (𝛿) + f (𝛿) − 1 ����� < 𝜗 ����� [𝛿dq f (𝛿)f (𝛿) + f (𝛿) + 1 ����� for 0 ≤ [ < 1, 0 < 𝜗 < 1, 0 ≤ 2(1−𝜗)1+[𝜗 < 1 and 𝛿 ∈ u. denition 3. a function f ∈ m∗sc,qv ([ , 𝜗) if and only if it satises ����� 𝛿dq f (𝛿)f (𝛿) − f (−𝛿) − 1 ����� < 𝜗 ����� [𝛿dq f (𝛿)f (𝛿) − f (−𝛿) + 1 ����� for 0 ≤ [ < 1, 0 < 𝜗 < 1, 0 ≤ 2(1−𝜗)1+[𝜗 < 1 and 𝛿 ∈ u. 2. results now, we give the properties for the 3 classes. first, we proceed with the coecient estimates for f ∈ m∗s,qv ([ , 𝜗). theorem 1. let f ∈ v . a function f ∈ m∗s,qv ([ , 𝜗) if and only if ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q 𝜗(2 + [) − 1 + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 ≤ 1 (4) for 0 ≤ [ < 1, 0 < 𝜗 < 1 and 0 ≤ 2(1−𝜗)1+[𝜗 < 1. proof. initially, we may prove the ’if’ part rst. we apply the method in (clunie and keogh, 1960). so, we write ��𝛿dq f (𝛿) − ( f (𝛿) − f (−𝛿))�� − 𝜗 ��[𝛿dq f (𝛿) + ( f (𝛿) − f (−𝛿))�� = �����−𝛿 − ∞∑︁ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 𝛿 𝜏 ����� − 𝜗 �����(2 + [)𝛿− ∞∑︁ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏z 𝜏 ����� ≤ ∞∑︁ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏r 𝜏 + r − 𝜗(2 + [)r + ∞∑︁ 𝜏=2 𝜗 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏r 𝜏 < [ ∞∑︁ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 + 1 − 𝜗(2 + [) + ∞∑︁ 𝜏=2 𝜗 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏 ] r = [ ∞∑︁ 𝜏=2 ((1 + [𝜗)[𝜏]q + 𝜗 ( 1 − (−1)𝜏 ) − ( 1 − (−1)𝜏 ) )a𝜏 − (𝜗(2 + [) − 1) ] r by considering inequality (4), we get∑∞ 𝜏=2 ( (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) ) a𝜏 − (𝜗(2 + [) − 1) ≤ 0, and by applying this inequality, we obtain ��𝛿dq f (𝛿) − ( f (𝛿) − f (−𝛿))�� − 𝜗 ��[𝛿dq f (𝛿) + ( f (𝛿) − f (−𝛿))�� = [ ∞∑︁ 𝜏=2 ( (1 + [𝜗)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) ) a𝜏 − (𝜗(2 + [) − 1) ] r ≤ 0 thus, ������ 𝛿dq f (𝛿) f (𝛿)−f (−𝛿) − 1 [𝛿dq f (𝛿) f (𝛿)−f (−𝛿) + 1 ������ < 𝜗 and hence f ∈ m∗s,qv ([ , 𝜗). conversely, let������ 𝛿dq f (𝛿) f (𝛿)−f (−𝛿) − 1 [𝛿dq f (𝛿) f (𝛿)−f (−𝛿) + 1 ������ = ����� −1 − ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 𝛿𝜏−1 (2 + [) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏z𝜏−1 ����� < 𝜗. since we know that the function f is analytic, continuous and non constant inu, then we apply the maximum modulus principle, so we can get © 2022 the authors. page 328 of 332 hern et. al. science and technology indonesia, 7 (2022) 327-332 ����� −1 − ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 𝛿𝜏−1 (2 + [) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏 𝛿𝜏−1 ����� = ��1 + ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 𝛿𝜏−1 ����(2 + 𝛼) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏 𝛿𝜏−1 �� ≤ 1 + ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) |a𝜏 ||𝛿 |𝜏−1 (2 + [) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) |a𝜏 ||𝛿 |𝜏−1 ≤ 1 + ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏r𝜏−1 (2 + [) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏r𝜏−1 = f (r). since f ∈ m∗s,qv ([ , 𝜗) and 0 < r < 1, we obtain 1 + ∑∞ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏r𝜏−1 (2 + [) − ∑∞ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏r𝜏−1 < 𝜗. (5) then, we let r → 1 in (5), we gain 1 + ∞∑︁ 𝜏=2 ( [𝜏]q − (1 − (−1)𝜏) ) a𝜏 ≤ 𝜗 ( (2 + [) − ∞∑︁ 𝜏=2 ( [𝜏]q[ + 1 − (−1)𝜏 ) a𝜏 ) and hence ∑∞ 𝜏=2 ( (1+𝜗[) [𝜏]q 𝜗(2+[)−1 + 𝜗(1−(−1)𝜏)−(1−(−1)𝜏) 𝜗(2+[)−1 ) a𝜏 ≤ 1 as required. this completes the proof of the theorem. corollary 1. if f ∈ m∗s,qv ([ , 𝜗) then a𝜏 ≤ 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) , 𝜏 ≥ 2. proof. from theorem 1, if f ∈ m∗s,qv ([ , 𝜗) then ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 ≤ 1 for 0 ≤ [ < 1, 0 < 𝜗 < 1 and 0 ≤ 2(1−𝜗)1+[𝜗 < 1. since ( (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 ≤ ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 ≤ 1, we obtain that a𝜏 ≤ 𝜗(2+[)−1 (1+𝜗[) [𝜏]q+𝜗(1−(−1)𝜏)−(1−(−1)𝜏) . the proof is completed. next, by applying similar way of methods, we may get the coecient properties for the functions which belongs to m∗c,qv ([ , 𝜗) andm ∗ sc,qv ([ , 𝜗). theresultsareshownintheorem 2 and theorem 3. theorem 2. let f ∈ v . a function f ∈ m∗c,qv ([ , 𝜗) if and only if ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q 𝜗(2 + [) − 1 + 2(𝜗 − 1) 𝜗(2 + [) − 1 ) a𝜏 ≤ 1 for 0 ≤ [ < 1, 0 < 𝜗 < 1 and 0 ≤ 2(1−𝜗)1+[𝜗 < 1. corollary 2. if f ∈ m∗c,qv ([ , 𝜗) then a𝜏 ≤ 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 2(𝜗 − 1) , 𝜏 ≥ 2. theorem 3. let f ∈ v . a function f ∈ m∗sc,qv ([ , 𝜗) if and only if ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q 𝜗(2 + [) − 1 + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 ≤ 1 for 0 ≤ [ < 1, 0 < 𝜗 < 1 and 0 ≤ 2(1−𝜗)1+[𝜗 < 1. corollary 3. if f ∈ m∗s,qv ([ , 𝜗) then a𝜏 ≤ 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) , 𝜏 ≥ 2. after that, we may get the growth property for functions in the class m∗s,qv ([ , 𝜗) in the next part. theorem 4. given that a function f be dened by (4) and belongs to the class m∗s,qv ([ , 𝜗). then for {𝛿 : 0 < |𝛿 | = r < 1}, r − 𝜗(2 + [) − 1 [2]q(1 + 𝜗[) r2 ≤ | f (𝛿)| ≤ r + 𝜗(2 + [) − 1 [2]q(1 + 𝜗[) r2. proof. first, it is obvious that [2]q(1 + 𝜗[) 𝜗(2 + [) − 1 ∞∑︁ 𝜏=2 a𝜏 ≤ ∞∑︁ 𝜏=2 ( (1 + 𝜗[)[𝜏]q 𝜗(2 + [) − 1 + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) a𝜏 and as f ∈ m∗s,qv ([ , 𝜗), we use the inequality in theorem 1 and it gives © 2022 the authors. page 329 of 332 hern et. al. science and technology indonesia, 7 (2022) 327-332 ∞∑︁ 𝜏=2 a𝜏 ≤ 𝜗(2 + [) − 1 [2]q(1 + 𝜗[) . (6) from (4) with |𝛿 | = r (r < 1), we can gain | f (𝛿)| ≤ r + ∞∑︁ 𝜏=2 a𝜏r 𝜏 ≤ r + ∞∑︁ 𝜏=2 a𝜏r 2 and | f (𝛿)| ≥ r − ∞∑︁ 𝜏=2 a𝜏r 𝜏 ≥ r − ∞∑︁ 𝜏=2 a𝜏r 2. lastly, by considering the inequalities (6), we may gain the result of theorem 4. in the next part, we shall gain the growth results for functions that belongs to m∗c,qv ([ , 𝜗) and m ∗ sc,qv ([ , 𝜗) by using a similar method. the results are shown in theorem 5 and theorem 6. theorem 5. given that a function f be dened by (4) and belongs to the class m∗c,qv ([ , 𝜗). then for {z : 0 < |𝛿 |= r < 1}, r − 𝜗(2 + [) − 1( [2]q − 1 ) + 𝜗 ( [2]q[ + 2 ) r2 ≤ | f (𝛿)| ≤ r + 𝜗(2 + [) − 1( [2]q − 1 ) + 𝜗 ( [2]q[ + 2 ) r2. theorem 6. given that a function f be dened by (4) and belongs to the class m∗sc,qv ([ , 𝜗). then for {z : 0 < |𝛿 | = r < 1}, r − 𝜗(2 + [) − 1 [2]q(1 + 𝜗[) r2 ≤ | f (𝛿)| ≤ r + 𝜗(2 + [) − 1 [2]q(1 + 𝜗[) r2. finally, we consider extreme points for these 3 classes. theorem 7. let f1(𝛿) = 𝛿 and f𝜏 (𝛿) =𝛿 − 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝛿 𝜏 , 𝜏 ≥ 2. then f ∈ m∗s,qv ([ , 𝜗) if and only if f (𝛿) = ∞∑︁ 𝜏=1 _𝜏 f𝜏 (𝛿) where _𝜏 ≥ 0 and ∞∑︁ 𝜏=1 _𝜏 = 1. proof. we adopt the technique by (silverman, 1975), we assume that f (𝛿) = ∞∑︁ 𝜏=1 _𝜏 f𝜏 (𝛿) = 𝛿 − ∞∑︁ 𝜏=2 _𝜏 ( 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) ) 𝛿 𝜏. next since ∞∑︁ 𝜏=2 _𝜏 ( 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) ) ( (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 ) = ∞∑︁ 𝜏=2 _𝜏 = 1 − _1 ≤ 1. therefore by theorem 1, f ∈ m∗s,qv ([ , 𝜗). conversely, suppose f ∈ m∗s,qv ([ , 𝜗). since a𝜏 ≤ 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) , 𝜏 ≥ 2, we may set _𝜏 = { (1 + 𝜗[)[𝜏]q + 𝜗 (1 − (−1)𝜏) − (1 − (−1)𝜏) 𝜗(2 + [) − 1 } a𝜏 , 𝜏 ≥ 2 and _1 = 1 − ∞∑︁ 𝜏=2 _𝜏. then ∞∑︁ 𝜏=1 _𝜏 f𝜏 (𝛿) = _1 f1(𝛿) + ∞∑︁ 𝜏=2 _𝜏 f𝜏 (𝛿) = 𝛿 − ∞∑︁ 𝜏=2 _𝜏 𝛿 + ∞∑︁ 𝜏=2 _𝜏 𝛿 − ∞∑︁ 𝜏=2 a𝜏 𝛿 𝜏 = f (𝛿). hence, we complete the proof. by using a similar method, we obtain the extreme points for the other 2 classes. © 2022 the authors. page 330 of 332 hern et. al. science and technology indonesia, 7 (2022) 327-332 theorem 8. let f1(𝛿) = 𝛿 and f𝜏 (𝛿) =𝛿 − 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 2(𝜗 − 1) 𝛿 𝜏 , 𝜏 ≥ 2. then f ∈ m∗c,qv ([ , 𝜗) if and only if f (𝛿) = ∞∑︁ 𝜏=1 _𝜏 f𝜏 (𝛿) where _𝜏 ≥ 0and ∞∑︁ 𝜏=1 _𝜏 = 1. theorem 9. let f1(𝛿) = 𝛿 and f𝜏 (𝛿) =𝛿 − 𝜗(2 + [) − 1 (1 + 𝜗[)[𝜏]q + 𝜗(1 − (−1)𝜏) − (1 − (−1)𝜏) 𝛿 𝜏 , 𝜏 ≥ 2. then f ∈ m∗sc,qv ([ , 𝜗) if and only if f (𝛿) = ∞∑︁ 𝜏=1 _𝜏 f𝜏 (𝛿) where _𝜏 ≥ 0 and ∞∑︁ 𝜏=1 _𝜏 = 1. 3. conclusions in thispaper, we introduced3newsubclassesof awithnegative coecients involving q-derivative and obtained their results for the coecient estimates, growth results and extreme points. 4. acknowledgment wegiveourgratitudetothenancial support (sbk0485-2021) and all the reference papers. references al-abbadi, m. h. and m. darus (2010). on subclass of analytic univalent functions associated with negative coecients. international journal of mathematics and mathematical sciences, 2010; 1–11 al shaqsi, k. and m. darus (2007). on certain subclass of analytic univalent functions with negative coecients. applied mathematical sciences, 1(21-24); 1121–1128 aral, a., v. gupta, and r. p. agarwal (2013). applications of q-calculus in operator theory. springer atshan, w. g. and h. y. ghawi (2012). on a new class of univalent functions with negative coecients. european journal of scientic research, 74(4); 601–608 breaz, d. and l. i. cotîrlă (2021). the study of the new classesofm-foldsymmetricbi-univalentfunctions. mathematics, 10(1); 75 bucur, r. and d. breaz (2020). properties of a new subclass of analytic functions with negative coecients dened by using the q-derivative. applied mathematics and nonlinear sciences, 5(1); 303–308 choo, c. p. and a. janteng (2013). estimate on the second hankel functional for a subclass of close-to-convex functions with respect to symmetric points. internationaljournal of mathematics analysis, 7; 781–788 clunie, j. and f. keogh (1960). on starlike and convex schlicht functions. journal of the london mathematical society, 1(2); 229–233 halim, s., a. janteng, and m. darus (2005). coecient properties forclasses with negative coecients and starlike with respect to other points. in proceeding of the 13th mathematical sciences national symposium, 2; 658–663 halim, s. a., a. janteng, and m. darus (2006). classes with negative coecients and starlike with respect to other points ii. tamkang journal of mathematics, 37(4); 345–354 ibrahim, r. w. 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(1975). univalent functions with negative coecients. proceedings of the american mathematical society, 51(1); 109–116 © 2022 the authors. page 332 of 332 introduction results conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper bi-univalent function classes defined by using an einstein function and a new generalised operator munirah rossdy1,2*, rashidah omar2, shaharuddin cik soh1 1school of mathematical sciences, college of computing, informatics and media, universiti teknologi mara, shah alam, selangor, 40450, malaysia2mathematical sciences studies, college of computing, informatics and media, universiti teknologi mara sabah branch, kota kinabalu campus, kota kinabalu, sabah, 88997, malaysia *corresponding author: munirahrossdy@uitm.edu.my abstractlet a be the class of all analytic and univalent functions f (z) = z+σ∞ k=2 akz k in the open unit disc 𝔻 = {z:|z|<1 }. s then represents the classes of every function in a that is univalent in 𝔻. for every f ∈ s, there is an inverse f −1. a function f ∈ a in 𝔻 is categorised asbi-univalent if f and its inverse g = f −1 are both univalent. motivated by the generalised operator, subordination principle, and thefirst einstein function, we present a new family of bi-univalent analytic functions on the open unit disc of the complex plane. thefunctions contained in the subclasses are used to account for the initial coefficient estimate of |a2|. in this study, we derive the resultsfor the covering theorem, distortion theorem, rotation theorem, growth theorem, and the convexity radius for functions of the class n s,m,k _ ,𝛼 (σ, e) of bi-univalent functions related to an einstein function and a generalised differential operator ds,m,k_ ,𝛼 f (z). we usethe elementary transformations that preserve the class n s,m,k _ ,𝛼 (σ, e) in order to attain the intended results. the required propertiesare then obtained. keywordseinstein function, subordination, distortion theorem, covering theorem, radius of convexity, bi-univalent functions received: 8 november 2022, accepted: 13 february 2023 https://doi.org/10.26554/sti.2023.8.2.195-204 1. introduction for the open unit disc 𝔻 = {z ∈ ℂ:|z|<1 }, we set a as denoting the class of f (z) = z + ∞∑︁ n=2 anz n , for z ∈ 𝔻 (1) analytic functions. s represents the class of all functions in a that are univalent in 𝔻 (for further detail on univalent functions, see duren (2001) ) and satisfy the standard normalisation condition f (0) = f ′(0) 1 = 0. the koebe one-quarter theorem (duren, 2001) demonstrates that each univalent function f ∈ s having a disc with a radius of 14 possesses an inverse function f −1 that can be defined by f −1( f (z)) = z, for z ∈ 𝔻, and f ( f −1(w)) = w, |w| < r0( f ), r0( f ) ≤ 1 4 the function f ∈ s is deemed as bi-univalent if f and f −1 are both univalent in 𝔻. let the class of bi-univalent functions in 𝔻 of the form (1) be denoted by ∑ . moreover, it is easily demonstrated that the series expansion of the inverse function can be written as follows: g(w) = f −1(w) = w − a2w2 + (2a22 − a3)w 3 (2) − (5a32 − 5a2a3 + a4)w 4 + · · · , for w ∈ 𝔻. class ∑ includes functions such as z1−z′ − log(1 − z), and 1 2 log( 1+z 1−z) . nevertheless, the well-known koebe function does not belong to ∑ . other typical instances of functions in s such as z − z 2 2 , and z 1−z2 , do not belong to ∑ . for references to related works on bi-univalent functions, see the revival paper https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.195-204&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.195-204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 by srivastava et al. (2010) , as well as several other studies (ali et al., 2012; oros and cotîrlă, 2022; srivastava et al., 2018). normalised analytic function operators are commonly utilised in the field of geometric function theory (gft), particularly differential and integral operators. a wide range of authors have written numerous articles on a variety of topics, including operators and novel generalisation. the differential operator, which was first introduced in 1975 by ruscheweyh (1975) , was a particularly major breakthrough. differential and integral operators were then presented in a different version by salagean (1983) . from there on, many academics have developed new operators and used them in numerous research topics involving gft. they include rossdy et al. (2022) , wanas (2019) , yunus et al. (2017) , elhaddad and darus (2021) , and frasin (2020) . in this paper, we provide some information regarding the differential operator that is applied to examine our new subclasses. according to rossdy et al. (2022) , the differential operator is defined by: definition 1.1 for f ∈ a, 0 < _ < 1, 0 < 𝛼 < 1, m ∈ ℕ = {1, 2, · · · }, b ∈ ℂ\z−0 , s ∈ ℂ, k ∈ ℕ0 , ds,m,k _ ,𝛼 f (z) =z + ∞∑︁ n=2 ( 1 + b n + b )s (3) [1 + _ (n − 1)(1 − _)m]kanzn we can see that when two functions of the class ∑ are linked in a convex combination, it need not be bi-univalent. even though the two functions of f1(z) = z1−z and f2(z) = z 1+iz are examples of bi-univalent functions, their sum, f1 + f2, is not univalent because its derivative no longer exists at 12 (1 + i). nevertheless, several elementary transformations preserve the class ∑ , as seen below (wei, 2017; sivasubramanian et al., 2014): i. rotation: if f ∈ ∑ , 0 ∈ ℝ, and g(z) = e−i\ f (ei\z), then g ∈ ∑ ; ii. dilation: if f ∈ ∑ , 0 < r < 1, and g(z)= 1r f (rz), then g ∈ ∑ ; iii. conjugation: if f ∈ ∑ and g(z) = f (z), then g ∈ ∑ ; iv. disk automorphism: if f ∈ ∑ , z ∈ 𝔻, and g(z) = f ( z+z 1+zz )− f (z ) (1−|z |2 ) f ′ (z ) , then g ∈ ∑ . v. omitted value transformation: if f ∈ ∑ with f (z) ± w for all z ∈ 𝔻, and g(z)= wf (z)w− f (z) , then g ∈ ∑ . in gft, determining coefficient estimates |an |(n ∈ ℕ) is essential because this allows details of these functions’ geometric properties to be obtained. the evaluation of analytic function coefficients determines the structural characteristics and particulars of gft. for example, in the univalent function set, the second coefficient |a2| implies the covering theorems, growth and distortion bounds. the renowned bieberbach conjecture, as proven by louis de branges (de branges, 1985) , posits that the coefficient inequality as written below is true for each f ∈ s provided by the taylor-maclaurin series expansion (1): |an | ≤ n (n ∈ ℕ\{1}), (4) where ℕ represents the set of all positive integers. lewin in his research lewin (1967) on bi-univalent functions of the class ∑ , discovered the bound |a2| < 1.51. brannan and clunie (1980) in their subsequent work proposed that |a2| ≤ √ 2. additionally, netanyahu (1969) demonstrated that maxf ∈∑ |a2| = 4 3 . in addition to estimating the coefficients for |a2| and |a3|, brannan and taha (1988) proposed the concepts of strongly bi-starlike functions of the order 𝛼 and strongly biconvex functions of the order 𝛼. following the lead of brannan and taha (1988) , other researchers (rossdy et al., 2021; soni et al., 2018; xu et al., 2012) have studied numerous subclasses of ∑ and determined the coefficient bounds for |a2| and |a3|. the geometric theory of bi-univalent functions shows more applications of lewin’s inequality (lewin, 1967) . an important implication is the distortion theorem. this theorem gives nonsharp upper and lower bounds for |f ′(z)| as f ranges over the class ∑ . the idea of subordination is then employed as defined below: definition 1.2 (miller and mocanu, 2000) given that f (z) ≺ g(z), with f being a subordinate to g, and both functions taken to be analytic. this indicates that f (z) = g(w(z)), where w is taken as analytic in 𝔻, which corresponds to |w(z)| < 1 and w(0) = 0. ma (1992) presented the subset of functions s∗(𝜙) = {f ∈ a : zf ′ (z) f (z) ≺ 𝜙(z), 𝜙 ∈ p, z ∈ 𝔻} in 1994, in which the symbol "≺" corresponds to the subordination stated in definition 1.2 above. ma (1992) studied several relevant topics, such as covering, growth, and distortion theorems. then, by inserting certain functions for 𝜙 in s∗(𝜙), we obtain various subclasses of a with distinct geometric analyses, such as those from the work by janowski (1970) , mendiratta et al. (2015) , and cho et al. (2019) . many characteristics of the analytic univalent functions are connected with differential and integral operators, such as coefficient bound, covering theorems, distortion theorems, growth theorems, inclusion properties, and radius of convexity; all of these have been investigated (omar and abdul halim, 2012; zhang et al., 2021; saheb and al-khafaji, 2021; kumar and sahoo, 2021; awasthi, 2017). yet, there has been relatively little research and discovery on the relevant features involving bi-univalent function subclasses. however, much attention has been focused on bi-univalent functions’ initial coefficients (al-ameedee et al., 2020; rossdy et al., 2021; soni et al., 2018). © 2023 the authors. page 196 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 gradshteyn and ryzhik (2014) published a formulation for the bernoulli polynomials in 1980, which has substantial uses in number theory and classical analysis. the bernoulli polynomials are featured in differentiable periodic functions in the integral form of the functions because they are used for polynomial approximation of these functions. the polynomials are used to represent the remainder term of the eulermaclaurin quadrature rule in its composite form as well. the bernoulli polynomials bn(x) are commonly defined (natalini and bernardini, 2003) using the generating function: g(x, t) b text et − 1 = ∞∑︁ n=0 bn(x) n! tn , |t| < 2𝜋, where for each nonnegative integer n, bn(x) are polynomials in x. since n−1∑︁ j=0 ( n j ) bj(x) = nxn−1 , n = 2, 3, · · · , the bernoulli polynomials can be calculated readily via recursion. the initial bernoulli polynomials are b0(x) = 1, b1(x) = x − 12 , b2(x) = x2 − x + 16 , b3(x) + x3 − 32 x 2 + 12 x, · · · moreover, bernoulli numbers bn b bn(0) can be directly generated by setting x = 0 in the bernoulli polynomials. the initial bernoulli numbers are b0(x) = 1, b1(x) = − 12 , b2(x) = 16 , b4(x) = − 130 b2n+1 = 0, ∀n = 1, 2, · · · furthermore, bernoulli numbers bn can be produced using the einstein function e(z): e(z) b z ez − 1 = ∞∑︁ n=0 bn n! zn. the name of einstein function is sometimes applied in mathematics for one of the functions (see (abramowitz and stegun, 1972; weisstein, 2022)): e1(z) b zez−1 , e2(z) b z 2ez (ez−1)2 , e3(x) b log(1 − e−z), e4(x) b zez−1 − log(1 − e −z). both e1 and e2 exhibit these desirable properties. e1 and e2 (convex functions) have a symmetric range along the real axis and starlike range about e1(0) = e2(0) = 1 and ℝ(e1(z)) > 0, ℝ(e2(z)) > 0, ∀z ∈ 𝔻. the series representation is given by e1(z) =1 + ∞∑︁ n=1 bn n! zn e2(z) =1 + ∞∑︁ n=1 (1 − n)bn n! zn , where bn denotes the nth bernoulli number. however, e′1(0) and e ′ 2(0) ≯ 0, therefore we must establish new functions e(z) b e1(z) + z and 𝔼(z) b e2(z) + 12 z. a significant function class will be known as p and p defines the function family 𝜙 that is restricted by the image domain of 𝜙 (𝜙 is a convex function with re (𝜙) > 0 in 𝔻) being symmetric along the real axis and starlike about 𝜙(0) = 1 with 𝜙′(0) > 0. we can now say that e, 𝔼 ∈ p. the following are the series representations: e(z) = 1 + z + ∞∑︁ n=1 bn n! zn , and 𝔼(z) = 1 + 1 2 z + ∞∑︁ n=1 (1 − n)bn n! zn , the contour integral (see (arfken and weber, 1999) ) can be used to define the nth bernoulli number, bn: bn = n! 2𝜋i ∮ z ez − 1 dz zn+1 , where the radius of the contour encircling the origin is less than 2𝜋i. el-qadeem et al. (2022b) presented outcomes relating to the first einstein function e1, while el-qadeem et al. (2022a) worked on the second einstein function e2. © 2023 the authors. page 197 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 definition 1.3 let ∑ indicate the bi-univalent function class in 𝔻. a function f ∈ ∑ is said to be in the class n s,m,k _ ,𝛼 ( ∑ , e) for 0 < _ < 1, 0 < 𝛼 < 1, m ∈ ℕ = {1, 2, · · · }, b ∈ ℂ\z−0 , s ∈ ℂ, k ∈ ℕ0, if the subsequent subordination satisfies: (1 − 𝛽) ds,m,k _ ,𝛼 f (z) z + 𝛽 ( ds,m,k _ ,𝛼 f (z) )′ ≺ e(z), (1 − 𝛽) ds,m,k _ ,𝛼 f (z) w + 𝛽 ( ds,m,k _ ,𝛼 f (w) )′ ≺ e(w), where ds,m,k _ ,𝛼 f (z) and g are denoted by (4) and (3), respectively. definition 1.4 (orloff, 2018) (complex logarithm function) the function log(z) is defined as log(z) = log(|z|) + i arg(z), where log |z| is the usual natural logarithm of a positive real number. inspired by sivasubramanian et al. (2014) , rossdy et al. (2022) , zhang et al. (2021) , saheb and al-khafaji (2021) , and el-qadeem et al. (2022b) , we propose in this paper a subclass of analytic bi-univalent function connected to the first einstein function, e(z). we obtain the covering theorem for bi-univalent functions; the theorem states that each function’s range in the class n s,m,k _ ,𝛼 ( ∑ , e) must encompass a disk with a minimum radius of 14 . we also find the distortion theorem, the growth theorem, and the convexity radius for functions in the class n s,m,k _ ,𝛼 ( ∑ , e). 2. main results 2.1 covering theorem firstly, we discover the covering theorem for the class n s,m,k _ ,𝛼 ( ∑ , e) provided by the following: theorem 2.1.1 the range of each function of the class n s,m,k _ ,𝛼 ( ∑ , e) includes the disk {w ∈ ℂ : |w| < 14 }. proof. a disk automorphism is used to derive the function f from a given function f ∈ n s,m,k _ ,𝛼 ( ∑ , e) and a fixed z ∈ 𝔻 where f(z) = f ( z+z 1+zz ) − f (z) (1 − |z |2) f ′(z) = z + a2(z)z2 + · · · , forz ∈ 𝔻. (5) then, we have f(z) =z +  −6 ( 2a2 ( 1+b 2+b )s [1 + _ (1 − 𝛼)m]k(1 + 𝛽)z+ 2 ( 6a2 ( 1+b 2+b )s [1 + _ (1 − 𝛼)m]k(1 + 𝛽) 2a3 ( 1+b 3+b )s [1 + 2_ (1 − 𝛼)m]k(1 + 2 𝛽)(3z 2 − 1) +12a3 ( 1+b 3+b )s [1 + 2_ (1 − 𝛼)m]k(1 + 2 𝛽)z + 5c21 z −3z 2 + 1 + c21 (5 − 15z 2) + 6c1z + · · · ) −3c1 − 6z ) + · · ·  z2 + · · · , z ∈ 𝔻 by performing a straightforward calculation, we get f(z) = z + [ (1 − 3z 2)(2a2a3 ( 1+b2+b )s[1 + _ (1 − 𝛼)m]k(1 + 2 𝛽) 2 ( a2 ( 1+b 2+b )s [1 + _ (1 − 𝛼)m]k(1 + 𝛽) + 2a3 ( 1+b 3+b )s 5c21 6 − 1 + · · · ) [1 + 2_ (1 − 𝛼)m]k(1 + 2 𝛽)z + 56c 2 1 z − c1 2 − z + · · · ) − z + 1 w ] z2 + · · · , z ∈ 𝔻, is analytic and bi-univalent in 𝔻. then, by incorporating © 2023 the authors. page 198 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 the inequality (4) with [ (1 − 3z 2)(2a2a3 ( 1+b2+b )s[1 + _ (1 − 𝛼)m]k(1 + 2 𝛽) 2 ( a2 ( 1+b 2+b )s [1 + _ (1 − 𝛼)m]k(1 + 𝛽) + 2a3 ( 1+b 3+b )s 5c21 6 − 1 + · · · ) [1 + 2_ (1 − 𝛼)m]k(1 + 2 𝛽)z + 56c 2 1 z − c1 2 − z + · · · ) − z + 1 w ] ≤ 2, we find that |w| ≥ 1 (1−3z 2 ) ( 2a2a3 ( 1+b 2+b ) s [1+_ (1−𝛼)m]k (1+2 𝛽 ) 2 ( a2 ( 1+b 2+b ) s [1+_ (1−𝛼)m]k (1+𝛽 )+2a3 ( 1+b 3+b ) s 5c2 1 6 −1+··· ) [1+2_ (1−𝛼)m]k (1+2 𝛽 )z+ 56 c 2 1 z − c1 2 −z+··· ) in view of brange’s work (de branges, 1985) we find that |a2(z)| ≤ 2, therefore |w| ≥ 1 4 2.2 distortion and rotation theorems the next theorem, which gives a vital estimate, is used to develop the distortion theorem and accompanying findings: theorem 2.2.1 for n s,m,k _ ,𝛼 ( ∑ , e), we have: ����zf ′′(z)f ′(z) − 2r21 − 3r2 ���� ≤ 4r1 − 3r2 , |z| = r < 1. (6) proof. a disk automorphism defined in (5) is used to derive the function f for a given function f ∈ n s,m,k _ ,𝛼 ( ∑ , e) and a fixed z ∈ 𝔻. hence, using the elementary transformation, we get f ∈ n s,m,k _ ,𝛼 ( ∑ , e), and a simple computation gives us a2(z) = (1 − 3|z |2)( f ′′(z)) 2( f ′(z)) − z̄ . (7) moreover, following the lead from brange’s work (de branges, 1985) , we can deduce that |a2(z)| ≤ 2|. as a result, we may get the inequality (6) by using the bound a2(z) in (7) and replacing z with z. after establishing theorem 2.2.1, the following distortion theorem can be shown: theorem 2.2.2 for each f ∈ n s,m,k _ ,𝛼 ( ∑ , e), we have: (1 − √ 3r) 2 √ 3−1 3 (1 + √ 3r) 2 √ 3+1 3 < | f ′(z)| ≤ (1 + √ 3r) 2 √ 3+1 3 (1 − √ 3r) 2 √ 3−1 3 , |z| = r < 1. (8) proof. from inequality (6), we obtain − 4r 1 − 3r2 < zf ′′(z) f ′(z) − 2r2 1 − 3r2 ≤ 4r 1 − 3r2 , |z| = r < 1. (9) by taking the real component of (8), we get 2r2 1 − 3r2 − 4r 1 − 3r2 < re { zf ′′(z) f ′(z) } < 2r2 1 − 3r2 + 4r 1 − 3r2 , |z| = r < 1. (10) since f ′(z)| ≠ 0 and f ′(0) = 1, it is possible to allocate a branch of log f ′(z) that has a single value and which disappears at the origin. as a result of utilising logarithmic differentiation and definition 1.4, we can find that re { zf ′′(z) f ′(z) } =z re { zf ′′(z) f ′(z) } = r 𝜕 𝜕r re{log | f ′(z)|}, z = rei\ . © 2023 the authors. page 199 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 we then employ the above identity in (10) and obtain 2r − 4 1 − 3r2 < 𝜕 𝜕r log | f ′(z)| < 2r + 4 1 − 3r2 , z = rei\ . (11) with \ as a constant, we integrate the inequality (11) from 0 to r with respect to r which yields the following expression: − 2 r∫ 0 r − 2 3r2 − 1 dr < r∫ 0 𝜕 𝜕r log | f ′(rei\)|𝜕r < −2 r∫ 0 r + 2 3r2 − 1 dr. by employing the partial fractions, we obtain − 2 r∫ 0 6 + √ 3 2 √ 3(3r + √ 3) + f rac6 − √ 32 √ 3(3r − √ 3)dr < r∫ 0 𝜕 𝜕r log | f ′(rei\)|𝜕r < −2 r∫ 0 −6 + √ 3 2 √ 3(3r + √ 3) + 6 + √ 3 2 √ 3(3r − √ 3) dr. using the technique of substitution, we get [( 2 √ 3 − 1 3 ) log( √ 3 − 3r) − ( 1 + 2 √ 3 3 ) log( √ 3 + 3r) ]r 0 < log | f ′(rei\)| < [( 2 √ 3 − 1 3 ) log( √ 3 + 3r) − ( 1 + 2 √ 3 3 ) log( √ 3 − 3r) ]r 0 then, by using the logarithmic quotient rule, we have log [ (1 − √ 3r) 2 √ 3−1 3 (1 + √ 3r) 2 √ 3+1 3 ] < log | f ′(rei\)| ≤ [ (1 + √ 3r) 2 √ 3−1 3 (1 − √ 3r) 2 √ 3+1 3 ] (12) finally, we attain (8) by exponentiating (12). as a result, we intend to point out the fact that the upper and lower bounds of the distortion factor | f ′(z)| for the class n s,m,k _ ,𝛼 ( ∑ , e) are obtained by essentially putting into consideration the real component of inequality (6) in theorem 2.2.1. however, by considering the imaginary part, we may get a condition for the rotation factor |arg f ′(z)|. hence, the theorem of rotation is as follows: theorem 2.2.3 for each f ∈ n s,m,k _ ,𝛼 ( ∑ , e), we have: |arg f ′(z)| ≤ 2 √ 3 log [ 1 + √3r 1 − √ 3r ] , |z| = r < 1. proof. from inequality (9), we attain 2r2 1 − 3r2 − 4r 1 − 3r2 < zf ′′(z) f ′(z) ≤ 2r2 1 − 3r2 + 4r 1 − 3r2 , |z| = r < 1. (13) by considering the imaginary component only from (13), we get: −4r 1 − 3r2 < lm zf ′′(z) f ′(z) ≤ 4r 1 − 3r2 , |z| = r < 1. (14) since | f ′(z)| ≠ 0 and f (0) = 1, it is possible to allocate a branch of log f ′(z) that has a single value and which disappears at the origin. thus, by employing the logarithmic differentiation and definition 1.4, we have lm zf ′′(z) f ′(z) = z 2f ′′(z) f ′(z) = r 𝜕 𝜕r arg f ′(z), z = rei\ . as a result of utilising the above inequality in (14), we obtain: −4 1 − 3r2 < 𝜕 𝜕r arg f ′(rei\) ≤ 4 1 − 3r2 , z = rei\ . (15) © 2023 the authors. page 200 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 the desired result is obtained by integrating the inequality (15) from 0 to r with respect to r by keeping \ constant. 2.3 radius of convexity another area where the inequality (6) is related is the radius of convexity. the theorem below estimates the convexity radius for functions in the class n s,m,k _ ,𝛼 ( ∑ , e): theorem 2.3.1 for every positive number, the function f ∈ n s,m,k _ ,𝛼 ( ∑ , e) maps the disk |z| < p into a convex domain such that p < √ 5−2 ≈ 0.23607. proof. based on inequality (6), we may evaluate: �����zf ′′(z)f ′(z) ����� ≤ 2r21 − 3r2 + 4r1 − 3r2 , |z| = r < 1. (16) next, we have a double inequality derived from (16), as represented below: 2r2 − 4r 1 − 3r2 < zf ′′(z) f ′(z) ≤ 2r2 + 4r 1 − 3r2 |z| = r < 1. subsequently, by using a simple computation, we get 1 − r2 − 4r 1 − 3r2 < 1 + zf ′′(z) f ′(z) ≤ 1 − r2 + 4r 1 − 3r2 |z| = r < 1. (17) by taking the real value from (17), we acquire re { 1 + zf ′′(z) f ′(z) } > 1 − r2 − 4r 1 − 3r2 , |z| = r < 1. but 1−r 2 −4r 1−3r2 > 0 for r < √ 5 − 2 ≈ 0.23607, and thence f maps such a disk |z|, r onto a convex domain. accordingly, this demonstrates our result. 2.4 growth theorem the distortion result from theorem 2.2.2 can be used to derive the lower and upper bounds of f ∈ n s,m,k _ ,𝛼 ( ∑ , e). we can subsequently prove the growth theorem as follows: theorem 2.4.1 for each f ∈ n s,m,k _ ,𝛼 ( ∑ , e), we have − √ 3 2 2(2+ √ 3) 3 [ (1 − √ 3r) 2(1+ √ 3) 3 2f1 ( 1 + 2 √ 3 3 , 2 + 2 √ 3 3 ; 5 + 2 √ 3 3 ; 1 − √ 3r 2 ) − 2f1 ( 1 + 2 √ 3 3 , 2 + 2 √ 3 3 ; 5 + 2 √ 3 3 ; 1 2 )] < | f (z)| ≤ 2 ( 2 √ 3−7 3 ) (3 + √ 3) (18) [ (1 − √ 3r) ( 2−2 √ 3 3 ) 2f1 ( 1 − 2 √ 3 3 , 2 − 2 √ 3 3 ; 5 − 2 √ 3 3 ; 1 − √ 3r 2 ) − 2f1 ( 1 − 2 √ 3 3 , 2 − 2 √ 3 3 ; 5 − 2 √ 3 3 ; 1 2 )] , |z| = r < 1. proof. let f ∈ n s,m,k _ ,𝛼 ( ∑ , e) and z = rei\ , where 0 < r < 1. we integrate the inequality from 0 to r with respect to r using theorem 2.2.2, r∫ 0 (1 − √ 3r) 2 √ 3−1 3 (1 + √ 3r) 2 √ 3+1 3 dr < r∫ 0 | f ′(z)|𝜕r ≤ r∫ 0 (1 + √ 3r) 2 √ 3−1 3 (1 − √ 3r) 2 √ 3+1 3 dr. next, we obtain  − √ 3(1 − √ 3r) 2(1+ √ 3) 3 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1− √ 3r 2 ) 2 2(2+ √ 3) 3  r 0 < [ | f (rei\)| ]r 0 ≤ (19) © 2023 the authors. page 201 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204  2 2 3 ( √ 3−2)√3(1 − √ 3r) ( 2−2 √ 3 3 ) 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; √ 3 − 1 1 − √ 3r2 )  r 0 . thus, a simple computation from (19) results in the double inequality (18). the growth and distortion theorems can be used to achieve the following inequality: theorem 2.4.2 for each f ∈ n s,m,k _ ,𝛼 ( ∑ , e), we have r ( (1−3 √ 3r) 2 √ 3−1 3 (1+3 √ 3r) 2 √ 3+1 3 ) − √ 3 2 2(2+ √ 3) 3 [ (1 − √ 3r) 2(1+ √ 3) 3 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1 2 )] < ���zf ′(z)f (z) ��� ≤ r ( (1+3 √ 3r) 2 √ 3−1 3 (1−3 √ 3r) 2 √ 3+1 3 ) 2 ( 2 √ 3−7 3 ) (3+ √ 3) [ (1 − √ 3r) 2(1− √ 3) 3 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1 2 )] , 0 < |z| = r < 1. proof. by utilising theorem 2.4.1 and theorem 2.2.2, we get ( (1−3 √ 3r) 2 √ 3−1 3 (1+3 √ 3r) 2 √ 3+1 3 ) − √ 3 2 2(2+ √ 3) 3 [ (1 − √ 3r) 2(1+ √ 3) 3 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1 2 )] < ��� f ′(z)f (z) ��� ≤ (20)( (1+3 √ 3r) 2 √ 3−1 3 (1−3 √ 3r) 2 √ 3+1 3 ) 2 ( 2 √ 3−7 3 ) (3+ √ 3) [ (1 − √ 3r) 2(1− √ 3) 3 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1 2 )] , |z| = r < 1. hence, from (20), by considering zf ′ (z) f (z) , we obtain r ( (1−3 √ 3r) 2 √ 3−1 3 (1+3 √ 3r) 2 √ 3+1 3 ) − √ 3 2 2(2+ √ 3) 3 [ (1 − √ 3r) 2(1+ √ 3) 3 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1+2 √ 3 3 , 2+2 √ 3 3 ; 5+2 √ 3 3 ; 1 2 )] < ���zf ′(z)f (z) ��� ≤ r ( (1+3 √ 3r) 2 √ 3−1 3 (1−3 √ 3r) 2 √ 3+1 3 ) 2 ( 2 √ 3−7 3 ) (3+ √ 3) [ (1 − √ 3r) 2(1− √ 3) 3 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1− √ 3r 2 ) − 2f1 ( 1−2 √ 3 3 , 2−2 √ 3 3 ; 5−2 √ 3 3 ; 1 2 )] , © 2023 the authors. page 202 of 204 rossdy et. al. science and technology indonesia, 8 (2023) 195-204 |z| = r < 1. therefore, the desired result is achieved. the combination of growth and distortion theorems produces a useful inequality where the starlikeness properties can be determined. 3. conclusion our motivation comes from the aspiration to find numerous novel and useful applications for the new generalised operator ds,m,k _ ,𝛼 f (z) proposed by rossdy et al. 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(2022). einstein functions. mathworld-a wolfram web resource xu, q. h., y. c. gui, and h. m. srivastava (2012). coefficient estimates for a certain subclass of analytic and bi-univalent functions. applied mathematics letters, 25(6); 990–994 yunus, y., a. akbarally, and s. a. halim (2017). strongly starlike functions associated with a new operator. in aip conference proceedings, 1870; 040001 zhang, c., s. khan, a. hussain, n. khan, s. hussain, and n. khan (2021). applications of q-difference symmetric operator in harmonic univalent functions. aims mathematics, 7; 667–680 © 2023 the authors. page 204 of 204 introduction main results covering theorem distortion and rotation theorems radius of convexity growth theorem conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper optimization of liquid smoke from shorea pachyphylla using response surface methodology and its characterization hasan ashari oramahi1, kustiati2, elvi rusmiyanto pancaning wardoyo2* 1faculty of forestry, university of tanjungpura, pontianak, 78124, indonesia2faculty of mathematics and natural science, university of tanjungpura, pontianak, 78124, indonesia *corresponding author: elvirusm1971@gmail.com/ elvi.rusmiyanto@fmipa.untan.ac.id abstractthe present study aims to optimize the processing variables producing liquid smoke from mabang wood (shorea pachyphylla) byusing response surface methodology (rsm). in this investigation, a design of experiment with different combinations of pyrolysistemperature and pyrolysis time on the liquid smoke yield from mabang wood was applied. the response of the optimal yield,temperature, and time of pyrolysis was predicted using a mathematical model. the optimal operating conditions for the process ofyielding 31.31% liquid smoke were identified at the pyrolysis temperature of 440◦c and pyrolysis time of 124 minutes. the effect ofpyrolysis temperature was more significant than the pyrolysis time (p<0.05). the liquid smoke samples were evaluated by a gc-ms.the main chemical compound of the liquid smoke were 1,2-ethanediol (19.26%), fluoromethane (6.69%), formic acid (4.96%),2-propanone (4.17%), acetic acid (18.64%), acetol (4.80%), furfural (9.94%), 2,4-hexadecanoic acid (3.45%), and guaiacol (2.93%). keywordsliquid smoke, optimization, pyrolysis, shorea pachyphylla, temperature received: 4 january 2022, accepted: 14 april 2022 https://doi.org/10.26554/sti.2022.7.2.257-262 1. introduction liquid smoke is a liquid obtained from condensation of gases during the pyrolysis process of wood in the absence of oxygen (lee et al., 2011; grewal et al., 2018). liquid smoke has been widely used for termicidal (adfa et al., 2017), antifungal (oramahi et al., 2018; barbero-lópez et al., 2019), algacidal (zheng et al., 2018), antimicrobial (zhang et al., 2019), and insect repelling activity (rahmat et al., 2014). the controlling of termites fungi using synthetic termicides or insecticides and synthetic fungicides are considered to have negative eect on human health and the environment (preston, 2000; manzoor et al., 2016; bedmutha et al., 2011). their continuous and excessive use causes human health eectious and environmental pollution. the liquid smoke obtained from azadirachta excelsa exhibited insecticidal activities against plutella xylostella l. (sapindal et al., 2018). optimization of the yield production process in liquid smoke is needed so that it can be used as a biopesticide. several researchers have noted the temperature and time of pyrolysis, as well as particle size of wood on the liquid smoke yield (akhtar and amin, 2012; crespo et al., 2017; hasan et al., 2017; oramahi et al., 2020b), and liquid smoke chemical compound (faisal et al., 2018; oramahi and wardoyo, 2019). the temperature of pyrolysis is the main factors in the yield of liquid smoke (akhtar and amin, 2012). the yield of liquid smoke gained from eucommia ulmoides olivers branches was 23.26% at 300-330◦c as the optimal temperature (hou et al., 2018). the highest phenol compound of liquid smoke was 2.0% at 300◦c of pyrolysis temperature, whereas, the highest acetic acid compound was 8% at 380◦c of pyrolysis temperature (faisal et al., 2018). fan et al. (2014) found the optimal liquid smoke yield was 43.62% at temperature of pyrolysis, heating rate, reactor pressure, and holding time were 495.5◦c, 19.4◦c, 5.0 kpa, and 50 min, respectively. the combination factors in pyrolysis process, as well as wood type, provide the maximum liquid smoke yield. the liquid smoke yield from tithonia diversifolia maximum was found at temperature of 536.74◦c, ow rate of 129.55 ml/min, particle size of 0.770 mm, and heating rate of 40 min (bhuyan et al., 2020), meanwhile, the optimal liquid smoke yield attainedfrompalmtrunkwas42.05%at temperatureof456.11◦c (oramahi et al., 2020b). qu et al. (2011) stated that the yield of liquid smoke obtained from rice straw was 43%, whereas those from corn stalk and peanut vine were 51 and 48%, respectively. the response surface methodology (rsm), a response https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.257-262&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.257-262 oramahi et. al. science and technology indonesia, 7 (2022) 257-262 optimization technique with several variabels (montgomery, 2017), has been used successfully to optimize pyrolysis process of liquid smoke or bio oil for pearl millet and sida cordifolia l. (laougé et al., 2020), oil palm trunk (oramahi et al., 2020a), indonesia ‘bengkirai’ wood (shorea laevis ridl) (oramahi et al., 2020a), risk husk (lazzari et al., 2019), and mixtures of waste (pinto et al., 2013). optimization of corncob hydrothermal conversion for yield of liquid smoke was studied by gan and yuan(2013),whofoundtheoptimumconditionoperatingwere gained at temperature, retention time, biomass solid content, and catalyst loadings were 280◦c, 12 min, 21%, and 1.03%, respectively. a previous study stated that particle size of wood, temperature, and time pyrolysis aect the yield of liquid smoke of ‘bengkirai’ wood from indonesia (oramahi et al., 2020b). currently, there is no research on the optimization of liquid smoke yields from mabang wood (shorea pachyphylla). in indonesian mabang wood has been used as a resources in furniture. it produces an enormous waste sawdust. therefore, this research intends to predict optimal liquid smoke yield obtained from mabang wood using the rsm and element analyses of the liquidsmokesamplegainedat theoptimumpyrolysisoperation condition were evaluated by gas chromatografy mass spectrometry (gc-ms) to identied the component of mabang liquid smoke. 2. experimental section 2.1 materials mabang wood used in the study was collected from a sawmill at pontianak. production of liquid smoke was accomplished accordingtotranggonoetal. (1996),darmadjiandtriyudiana (2006), and oramahi et al. (2018). 2.2 experimental design based on the literature (akhtar and amin, 2012; crespo et al., 2017) and our previous study (oramahi et al., 2020b), two critical parameters namely, pyrolysis temperature (x1), and pyrolysis time (x2) was acknowledged as signicant factors that may impact the yield of liquid smoke by pyrolysis. an rsm was used in order to optimize liquid smoke yield from mabang wood. based on rsm design, two-factor, three coded level, and the code level of temperature 400, 425, and 450◦c and time 105, 120, and 135 minutes are demonstrated in table 1. table 1. range and level of independent variables variables symbol coded range and levels -1 0 1 temperature of pyrolysis (◦c) x1 400 425 450 times of pyrolysis (min) x2 105 120 135 the second-order polynomial equation and all interaction terms can be written as follows: y = 𝛽0 + k∑︁ i=1 𝛽ixi + k∑︁ i=1 𝛽iix 2 i + ∑︁ i ∑︁ j 𝛽i jxixj + y (1) where 𝛽0 is the constant regression coecients, whereas 𝛽i, 𝛽ii, 𝛽i j are the coecients of linear, quadratic, as well as eects of interaction, whereas xi, xj are the coded independent variables, and y is the error. 2.3 rsm and statistical analysis all data acquired were analyzed using software package statisticaversion6.0 (statsoft inc.) andsoftwaresasversion 8.2 (sas institute inc.). the regression analysis was accomplish by statistica and sas. the signicance of each term was set on f-test with p-value less than 0.05 (p≤0.05). 2.4 chemical composition characterization of liquid smoke the gc-ms identied of the liquid smoke chemical component was carried out on shimadzu (qp-210s). the conditions gc–ms assay were (a) capillary columns was db-624, 30 mx 0.25 mm; (b) the injection temperature was 250◦c, (c) column temperature program was 60-200◦c. helium was used as carier gas with ow rate of 40.0 ml/min. briey, the injection volume of sample was 1 ml. the temperature maintained at 60-200◦c. the chemical component was analysis by comparing with data from standard library (mun and ku, 2010; oramahi et al., 2018) and calculated by the integrated peak areas. 3. results and discussion 3.1 optimum operating conditions to achieve maximum liquid smoke yield a total of 12 experimental and the combination of independent variable are chosen to maximize the liquid smoke yield (table 2). all data were analyzed using multiple regression to express the model, following the quadratic polynomial equation. the model taken is created on the recommendations agreed by rsm. interaction relationships of operating process on liquid smoke yield (table 3). the indicated that temperature of pyrolysis contributed signicantly eect on mabang liquid smoke yield, while the eect on x2 variable was not signicant. oramahi and rusmiyanto (2021) have investigated that temperature is the most important factor eecting liquid smoke yield. similar result was reported by islam et al. (2005). they satated that the dierence in the percentage of liquid smoke yield is predisposed by the pyrolysis temperature. the results of the pyrolysis of liquid smoke at low temperatures are less than at high temperatures because at low temperatures the combustion of wood is not enough, therefore yielding less liquid smoke product. the maximum liquid smoke yield of 31.31% for mabang wood were obtained at the optimal temperature of 440◦c and © 2022 the authors. page 258 of 262 oramahi et. al. science and technology indonesia, 7 (2022) 257-262 table 2. rsm design for liquid smoke yield obtained from mabang wood run coded variable level the yield of liquid smoke from mabang wood (%) x1 x2 experimental predicted 1 -1 -1 23.50 24.63 2 1 -1 31.50 30.71 3 -1 1 27.00 28.83 4 1 1 31.50 30.63 5 -1 0 29.00 26.83 6 1 0 29.50 31.17 7 0 -1 29.50 29.17 8 0 1 31.00 30.83 9 0 0 33.00 30.50 10 0 0 30.00 30.50 11 0 0 30.00 30.50 12 0 0 28.50 30.50 table 3. resulths of variance analysis and regression coecients for the mabang liquid smoke yield variation sources polynomial coecient error t-value pr>t intercept 30.50 0.88 34.81 <0.000 x1 2.17 0.78 2.77 0.033 x2 0.83 0.78 1.06 0.329 x1*x1 -1.50 1.17 -1.28 0.249 x2*x1 -0.88 0.96 -0.91 0.397 x2*x2 -0.50 1.17 -0.43 0.685 coecient of variation= 6.51%, r2= 0.67 time of 124 minute. the reported maximum liquid smoke of similar result was reported by oramahi et al. (2020b) with the maximum liquid smoke of 30.31% from pyrolysis shorea laevis ridl at the particle size of wood and and temperature pyrolysis were 3.85 mm and 400◦c, respectively. a three-dimensional response surface methodology plot of liquid smoke from mabang versus pyrolysis temperature and pyrolysis time is given in figure 1. the association between variables and responses was illustrated in the response surface representation (3d) and the contour plots (2d) generated by the model for the yield of mabang liquid smoke. an empirical model for the results of mabang liquid smoke was gained as trails and the 3d response surface curve and contour plots (2d) is given in figure 1. the yield of mabang liquid smoke equation consists of a term of second-order, is represented as equation (2). y =30.50 + 2.17x1 + 0.83x2 − 1.50x12− 0.88x1.x2 − 0.50x22 (2) figure 1. contour (a) and response surface plot (b) of mabang liquid smoke yield for pyrolysis temperature (x1) and pyrolysis time (x2) where, y is the estimated mabang liquid smoke yield, x1 is pyrolysis temperature, whereas, x2 is pyrolysis time. the regression analysis was obtained from the equation 2, where the yield of liquid smoke is illustrated as a function of temperature and time of pyrolisis. it reected the accuracy of the model can be assessed by r2. the r2 for mabang liquid smoke is 0.67 this shows that 67.00% of the total variation in the results of mabang liquid smoke comes from the experimental variables studied (table 3). li et al. (2017) show that the experimental values were predicted by a second-order polynomial model. as already mentioned, the linear pyrolysis temperature (x1) had a signicance (p<0.05), which indicates that the temperature of the pyrolysis variable (x1) is the most signicant factor in the liquid smoke yield (p<0.05). 3.2 the chemical compound of liquid smoke from mabang wood identication of compounds in selected of liquid smoke optimal yield for optimal pyrolysis temperature and pyrolysis time was accomplished by gc-ms. the composition of liquid smoke from mabang wood at optimal temperature (400◦c) and the main compounds of liquid smoke identied were 1,2ethanediol (19.26%), uoromethane (6.69%), formic acid (4.96 %), 2-propanone (4.17%), acetic acid (18.64%), acetol (4.80%), furfural (9.94%), 2,4-hexadecanoic acid (3.45%), and guaiacol (2.93%). similarly, suresh et al. (2019) main identied substances in the liquid smoke obtained from softwood mixture was 40-45% such as phenols, aldehyde, and organic acid. they reported that the liquid smoke showed the strongest antifungal activity against trametes versicolor. souza et al. (2012) reported that main compounds observed of the two liquid smoke obtained from eucalyptus sp. and commercial folier fertilizer company were formic acid (4.96%), acetic acid (18.64%), and © 2022 the authors. page 259 of 262 oramahi et. al. science and technology indonesia, 7 (2022) 257-262 table 4. phytochemical compound of mabang liquid smoke identied by gc-ms analysis at the condition of optimum temperature pyrolysis rt phytochemical compound area (%) 2.130 carbamimidic acid 0.13 2.464 acetaldehyde 1.18 2.526 1,2-ethanediol 19.26 2.600 fluoromethane 6.69 2.690 formic acid 4.96 3.474 propionaldehyde 0.28 3.551 2-propanone 4.17 3.708 methyl ketone 0.26 3.881 methyl acetate 1.46 5.567 2,3-butanedione 1.38 5.796 2-butanone 0.68 6.100 formic acid 0.24 6.289 furan 0.41 7.737 acetic acid 18.64 9.472 acetol 4.80 11.846 propanoic acid 1.84 14.212 1-hydroxy-2-butanone 1.62 15.433 propylene oxide 0.76 15.925 butanoic acid 0.24 16.843 2-furanmethanol 1.48 17.142 furfural 9.94 18.828 furfuryl alcohol 0.84 19.307 2-butanone 1.05 20.532 2-cyclopenten-1-one 0.54 20.947 ethanone 0.33 23.543 ethenyl ester 1.63 23.651 2,3-pentanedione 0.98 23.781 5-methylfurfural 2.35 26.866 2,4-hexadienoic acid 3.45 29.382 guaiacol 2.93 33.711 2-methoxy-4-methyl-phenol 1.97 37.083 4-ethyl-2-methoxy-phenol 0.51 40.277 2,6-dimethoxy-phenol 1.86 44.153 1,2,4-trimethoxybenzene 1.10 2,4-hexadienoic acid (3.45%), meanwhile, the phenols compound were guaiacol (2.93%), 2-methoxy-2-methyl phenol (1.97%), and 1,2,4-trimethoxy benzene (1.10%). the chemical composition of liquid smoke from almond shell including phenols and their derivatives (30.13%), organic acids (40.89%), furan derivative (7.43%), and ketone group (15.85%). the abundant compound of organic acid was acetic acid (32.18%), whereas the phenols compound was phenol (5.54%) (li et al., 2017). wang et al. (2018) reported that the main chemical component of liquid smoke prepared by hydrothermolysis of the cotton stalk were acids, phenols, ketone, and furan derivatives. mungkunkamchao et al. (2013) investigated that liquid smoke from eucalyptus were acetic acid (30.39%), propanoic acid (6.08%), phenol (3.75%), 2-methoxyphenol (12.31%), methyl-thiirane (26.96%), 2-furancarboaldehyde (6.39%), and 2-methoxy-4-methyl phenol (6.27%). liquid smoke obtained from coconut shell at nal pyrolysis temperature of 575◦c including phenolic, acid and ketone (gao etal.,2016). rabiuetal. (2019) characterized liquidsmokeobtained from palm kernel shell were phenols, eldehydes, ketones, and esters. liquid smoke of sawdust contains several main chemical compound including: palmitic acid (19,40%), dotriacontane (15,21%), benzenesulfonic acid, 4-hydroxy (10,69%), acetic acid (9,81%), and 1,2-dihydroxyoctadecane (7,96%). lu et al. (2019) reported that main compound of liquid smoke obtained from cunninghamia lanceolate waste were acids, phenols, alcohols, kenones, and esters. gc-ms analysis of the optimized liquid smoke from cotton stalk designated the occurrence of main chemical compounds such as acids, phenols, benzamide, and aromatic compounds (li et al., 2017). aguirre et al. (2020) investigated that the dominant component of liquid smoke obtained from forest pine were acetic acid (3.09%), 1-hydroxi-2-propanone (1.39%), hydroxiacetaldehyde (1.18%), furfural (0.31%), and levoglucosan (0.16%). the quantity dierence of chemical compound of liquid smoke due to the dierent types of raw materials for produce of liquid smoke, proximate anlysis such as cellulose, hemicellulose, lignin, temperature (demiral and ayan, 2011; abnisa et al., 2013) and time pyrolysis (oramahi et al., 2020b). however, for sake of practicality, we concentrating on pyrolysis temperature and time pyrolysis in this study. 4. conclusions the optimum liquid smoke yield study was conducted with dierent pyrolysis temperature and pyrolysis time using rsm. the predicted optimum pyrolysis condition was obtained at pyrolysis temperature of 440◦c and pyrolysis time of 124 min for maximum predicted liquid smoke yield of 31.31%. the abundant chemical compound of the liquid smoke was 1,2ethanediol, uoromethane, formic acid, 2-propanone, acetic acid, acetol, furfural, 2,4-hexadecanoic acid, and guaiacol. the ongoing study and recent information on liquid smoke proposed noteworthy potential for production and application of liquid smoke in agriculture and forestry. 5. acknowledgment the authors is very grateful acknowledge directorate general of higher education of indonesia through research grant (fundamental research) in 2019 and 2020. references abnisa, f., a. arami-niya, w. w. daud, j. sahu, and i. noor (2013). utilization of oil palm tree residues to produce bio-oil and bio-char via pyrolysis. energy conversion and management, 76; 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273–281 © 2022 the authors. page 262 of 262 introduction experimental section materials experimental design rsm and statistical analysis chemical composition characterization of liquid smoke results and discussion optimum operating conditions to achieve maximum liquid smoke yield the chemical compound of liquid smoke from mabang wood conclusions acknowledgment science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2016) 20-24 article http://sciencetechindonesia.com @2016 published under the terms of the cc by nc sa 4.0 license 20 organometallic [fe3o(oocc6h5)6(h2o)3](no3) as intercalant of bentonite hasja paluta utami1,* and donny marihot siburian1 1departement of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail : hasjapaluta8@gmail.com abstract intercalation of organometalic compounds [fe3o(oocc6h5)6(h2o)](no3)∙nh2o on bentonite by weight ratio of bentonite:organometallic (1 : 1); (1 : 2); (1 : 3); and (1 : 4) has been carried out. the intercalation bentonite was characterized using ft-ir spectrophotometer, xrd and xrf anayses. characterization using ft-ir spectrophotometer showed higher intensity of peak wavenumber at 470.6 cm-1 for fe3-o vibration on the ratio (1 : 3). while xrd characterization showed the shift of diffraction angle of 2θ was 5.2° and has bacal spacing of 16.8 ǻ. in the xrf characterization, the intercalation process of organometalic compounds [fe3o(oocc6h5)6(h2o)](no3)∙nh2o on bentonite was occurred optimally with percentage of metal oxide reached 71.75 %. keywords: intercalation, bentonite, organometallic, [fe3o(oocc6h5)6(h2o)](no3)∙nh2o. introduction bentonite is a layered material contain inorganic minerals who can find easily in natural (abderrazek et al, 2016). bentonite are used as adsorbent, catalyst, ion exchange, and various industrial applications (santos et al, 2016). in the application of bentonite as adsorben have some weakness, due to impurities of some minerals that can make the adsorption is not optimal. therefore, to optimize the adsorption process then bentonite should be activated. the procces activation of bentonite is intended to separate the impurities naturally from bentonite. in general, there are two step of activation procces for activation including physically and chemically processes. on physical processes is needed to combution in a high temperature causes water moleculs from crystal and other inorganic constituents, so that two cluster oh who bondered each other, they have to detach one water molecul (scoonheydt et al, 2008), while on chemical processes by using acid mineral such as sulfuric acid is intended to omit the metals that be found in bentonite and banded in ion h+ which is originated from acid. therefore the layer who as an insertion entry will be larger. the modification of bentonite is expected to produce bentonite which can be conducted by insertion of molecules, compounds, and organic/inorganic complexes. the research of layer materials intercalation including bentonite using metal oxides shows distance between layer is a litlle small (yang et al, 2005). thus higher compound with positive charge is needed as intercalant of bentonite. this research was conducted an intercalation process of bentonite using a organometalic compund as insertion. organometalic compound [fe3o(oocc6h5)6(h2o)](no3)∙nh2o have advantage such as high reactivity, high cation size, and also easy to synthesis. in this research, various weight of organometallic compond has been used to know the optimal intercalation process. the ratio of bentonite:organometallic complex was article history submitted: 23 july 2016 accepted: 5 august 2016 doi: 10.26554/sti.2016.1.1.20-24 (1:1); (1:2); (1:3); and (1:4). product of insertion was characterized by spectrofotometer ft-ir, xrd, and xrf analyses in order to know the optimal insertion process. experimental section materials natural bentonite was obtained from jambi province, indonesia. sulfuric acid, iron(iii) nitrate, sodium benzoate, and sodium hydroxide was obtained from merck and directly used after purchased. deionized water was supplied from purite®. preparation of bentonite (ozcan, 2016) the nature bentonite is prepared by physically and chemically proceses. 100 g of natural bentonite was heated using furnace at 400 oc for two hours then the material was kept at room temperature over night. the bentonite then was acidified using sulfuric acid for two hours. bentonite after treatment was characterized using ft-ir spectrophotometer, xrd, and xrf. synthesis of organometalic compunds [fe3o(oocc6h5)6(h2o)](no3)∙nh2o (uchida et al, 2008) synthesis of organometallic compounds was carried out by mixing a 32 g of iron(iii)nitrate that has been dissolved in 100 ml of water. in the solution was added 24 g sodium benzoate and the mixtures were stirred by magnetic stirrer for 15 minutes. the brown orange solution will be formed, filtered, washed by water to obtain [fe3o(oocc6h5)6(h2o)](no3) ∙nh2o. organometallic compound was characterized using ft-ir spectrophotometer. intercalation of bentonite with organometalic compound [fe3o(oocc6h5)6 (h2o)](no3)∙nh2o (gil et al, 2009) bentonite was mixed with 200 ml water to form white suspension (reactan a). organometallic compound as intercalant compound was prepared by adding 100 ml sodium hydroxide (naoh) 1 m into 15 g of organometallic compound (reactan b). reactan a and b was mixed and the mixtures was utami et al. / science and technology indonesia 1(1) 2016:20-24 @2016 published under the terms of the cc by nc sa 4.0 license 21 refluxed with gentle stirring for 24 hours at room temperature under nitrogen gas. the product intercalation of bentonite with organometallic compounds was washed with water and dried at 90 oc. in order to know the optimum intercalation process, the ratio of bentonite:organometallic compound was applied (1 : 1); (1 : 2); (1 : 3); and (1 : 4). the bentonite intercalated organometallic compounds were characterized using ft-ir spectrophotometer, xrd and xrf analysis. results and discussion synthesis and characterization of organometallic compounds [fe3o (oocc6h5)6(h2o)3](no3)∙nh2o synthesis of organometallic compounds [fe3o(oocc6h5)6 (h2o)3](no3)∙nh2o was carried out under air conditions without protection of an inert gas, which has different from almost synthesis of organometallic complexes (szafran et al, 1991). organometallic compounds [fe3o(oocc6h5)6 (h2o)3](no3)∙nh2o has light brown crystals. the organometallic compounds were then characterized using ftir spectrosphotometer aimed to identifying functional groups showed in figure 1. figure 1. ft-ir spectrum of organometallic compounds [fe3o(oocc6h5)6(h2o)3](no3) ∙nh2o table 1. wavenumbers data of organometallic compounds [fe3o(oocc6h5)6(h2o)3] (no3)∙nh2o wavenumber (cm-1) functional groups 3410.1 (o-h) 3070.6  (ar-h) 1419.61612.4  (c-h), (c-o),(cc) 709.8 469.0  (n-o)  (fe-o) figure 1. shows the peaks of functional groups of organometallic compounds appearing at wavenumbers 4004000 cm-1. the main peaks of the organometallic compound appear at the 469 cm-1 for fe-o vibration (hasegawa et al, 2007). at the wavenumber 709.8 cm-1 for the n-o vibration as the counter ion of the benzoate ligand. [fe3o(oocc6h5)6 (h2o)3](no3)∙nh2o has a c-h vibration, the c-o vibration, and the c-h vibration, which appears at the wavenumbers 1419.6 cm-1, 1612.4 cm-1 (lesbani et al, 2008). wavenumber 3070.6 cm-1 is indicated for ar-h bend vibration. the absorption band at 1689.6 cm-1 for o-h vibration indicating the presence of water ligands in organometallic compounds, which has also strongly appeared by vibration at 3410.1 cm-1. the data of wavenumbers of organometallic compounds [fe3o(oocc6h5)6 (h2o)3] (no3)∙nh2o are summarized in table 1. identification of natural bentonite and bentonite intercalated organometallic compounds [fe3o(oocc6h5)6 (h2o)3](no3)∙nh2o using ft-ir spectrophotometer before the intercalation process, natural bentonite was characterized using ft-ir spectrophotometer aimed at identifying functional groups. ft-ir spectra of natural bentonite at figure 2(a) shows vibration of al-oh-al vibration in wavenumber 3626.1 cm-1 and vibration of al-oh-al at wavenumber 910.4 cm-1. the water content that acts as an interlayer molecule on bentonite appears as a strech vibration of h-o-h observed at the wavenumber 3448.7 cm-1 while the ho-h bend vibration appears at 1635.6 cm-1. the absorption at 1033.8 cm-1 indicate the bend vibration of si-o-si (derrick et al, 1999). there are two stages to remove impurities on bentonite i.e. heating at 400oc and acidification using sulfuric acid (h2so4). on bentonite with heating at 400°c causes a change in deformation of the h2o bond, since the existing h2o is released, therefore the bentonite peak becomes widened and expanded so that it eventually collapses at 400°c. the success of this process are characterized by changes in functional groups with the shift in the wavenumbers as seen in figure 2 (b). the absorption bands in figure 2 (b) of the al-oh-al vibration are shifted at 3695.6 cm-1 and quartz minerals are shifted at 694.3 cm-1 wavenumbers. vibration of stretch and bend of h-o-h appear on the same wavenumber in natural bentonite, ie at 3448.7 cm-1 and at 1635.6 cm-1. the stretching and bending vibration of si-o-si are shown in the 1033.8 cm-1 and 532 cm-1 and the al-oh-al bending vibrations remain at the 910.4 cm-1. the second activation process of natural bentonite is acidification using sulfuric acid. acidification using sulfuric acid aims to remove small metals as impurities attached to bentonite. this activation will open interlayer of bentonite. ft-ir spectrum in figure 2 (c) shows the shift of wavenumbers of bentonite after acid activation. the absorption band for al-ohal stretching vibration shifts to wavenumber 3672.4 cm-1. the h-o-h stretching vibration shifts to wavenumber 3425.5 cm-1 and the si-o-si stretching vibration stay at the wavenumber 1041.5 cm-1. the bending vibrations of al-oh-al appearing at 910.4 cm-1 and the h-o-h bending vibrations appear at 1635.6 cm-1. similar to natural bentonite and bentonite heating at 400°c there is no shift in wavenumbers, stretching and bending vibrations of si-o-si stay at wavenumber 532 cm-1. intercalation process of bentonite with organometallic compound was completely conducted by adding water to bentonite which is continued with addition of sodium oxide (naoh). this goal is to build a suspension for easy intercalation process. in the process of intercalation, there is no contact of oxygen form the air, which has protected by introducing n2 gas. the process of intercalation of bentonite with these utami et al. / science and technology indonesia 1(1) 2016:20-24 @2016 published under the terms of the cc by nc sa 4.0 license 22 organometallic compounds is carried out by varying the weight ratio, between the weight of the bentonite and the organometallic weight : (1: 1), (1: 2), (1: 3) and (1: 4). this experiment was carried out in order to know the optimum intercalation process. the results of intercalation of organometallic compounds with the weight ratio of (1: 1), (1: 2), (1: 3) and (1: 4) were characterized using ft-ir spectrophotometer to see functional groups formed as in figure 3. in figure 3 (d), it is seen that the vibration of the fe-o organometallic compound appears at a wavenumber of 462.5 cm-1. the strong of absorption bands for al-oh-al stretch vibrations shifted to 3618.4 cm-1. the o-h stretching vibration widened at 3448.7 cm-1. this indicates the presence of an o-h group on benzoate as well as a benzoate ligand in the form of c-c vibration, c = c vibration, c = o vibration appearing at wavenumbers 1388.7 1635 cm-1. si-o-si stretch vibration at wavenumber 1018.4 cm-1 and al-oh-al bending vibrations that appear on wavenumbers 910.4. stretching and bending vibrations of al-o-si are seen at 524.6 cm-1. figure 2. ft-ir spectrum of a) natural bentonite. b) bentonite with heating at 400 oc c) bentonite with acidification in the result of bentonite intercalation of organometamic compound in figure 3 (e) (1: 2) it is seen that the vibration of fe-o organometallic compound appears at wavenumber 470.6 cm-1. the emergence of absorbing bands for the vibration of the al-oh-al strain shifted at the wavenumber 3618.4 cm-1. the oh vibration widened at 3448.7 cm-1, the vibration of the c-c, the vibration of c = c, the vibration c = o at 1388.7 1635 cm1 and vibration of si-o-si strain at 1033.8 cm-1. al-oh-al buckling vibrations that appear at the 910.4 cm-1. strecthing and bending vibrations of al-o-si are appeared at 532.3 cm-1 in the result of bentonite intercalation of organometallic compound figure 3 (f) (1: 3) it is appeared that the emergence of strong absorption at wavenumber 470,6 cm-1 for vibration of fe-o organometallic compound. the presence of absorbing bands for the oh vibration is widened in the wavenumber 3448.7 cm-1. the vibration of the c-c, the vibration of c = c, the vibration c = o occurs at the wavenumbers 1388.7 – 1635 cm-1, si-o-si at 1033.8 cm-1. al-oh-al buckling vibrations that appear at 910.4 cm-1 wavenumbers, whereas, stretching vibration of al-o-si bends are appeared at 524.6 cm-1. these vibrations are almost similar with vibration in figure 3g. the ft-ir spectra of figure 3 show that the variation in the weight ratio of intercalated bentonite did not differ significantly. in order to know the optimal intercalation process, characterization using xrd was conducted for further analysis. figure 3. ft-ir spectrum of intecalated bentonite, d) 1:1, e) 1:2, f) 1:3, g) 1:4. identification of natural bentonite and bentonite intercalated organometallic compounds [fe3o(oocc6h5)6(h2o)3] (no3)∙nh2o using x-ray diffraction the objectives analysis using xrd is to look at the structural changes that occur in bentonite after intercalation by observing the diffraction angle change (2θ). bentonite is a class of minerals that contain montmorillonite as main fraction. (brindley et al, 1990 ). bentonite shows the observed montmorillonite at 2θ from 3 6o. this is evident from the diffraction angle (2θ) of natural bentonite, bentonite with heating at 400°c and bentonite with acidification using sulfuric acid ie the shifting angle of motnmorillonite diffraction at 4.1o, 3.3o and 4.1o. the existence of diffraction at the 2θ angle of 20o and 26o as shown in figure 4 (a), (b), and (c) indicates the existence of utami et al. / science and technology indonesia 1(1) 2016:20-24 @2016 published under the terms of the cc by nc sa 4.0 license 23 other minerals ie quartz and illite. if bentonite is intercalated by molecules and compounds, there will be xrd diffraction patterns shift of montmorillonite, quartz, and illite (bertella et al,. 2011 ). in figure 4 (d) shows the weight ratio (1: 1), there is a shift in the diffraction angle of 2θ montmoriloite in bentonite of 5.2o with basal spacing of 16.7 ǻ. in comparison (1: 2) presented in figure 4 (e) also seen shift angle diffraction 2θ montmoriloit at 5.3o with basal spacing 16.4 ǻ. in figure 4 (f), the ratio (1: 3) also shows a shift in the angle of diffraction of 2θ montmoriloite at bentonite of 5.2o with basal spasing of 16.8 ǻ. the shift of the diffraction angle 2θ in the ratio of the weight of bentonite to the organometallic compound [fe3o (oocc6h5)6(h2o)3](no3)∙nh2o can be seen in figure 4 (d), (e), (f), and (g). figure 4 diffraction patterns of a) natural bentonite, b) bentonite with heating at 400 oc c) bentonite with acidification d) bentonit:organometallic 1:1, e) 1:2, f) 1:3, and g) 1:4. in the ratio (1: 4) shown in figure 4 (g) it does not have a 2θ montmorillonite diffraction angle shift in bentonite but has a basal spacing of 24 ǻ. this can not be said to be optimal because there is no shift in the diffraction angles of 2θ montmorillonite. the success of bentonite intercalation of organometallic compounds can be seen from the shifting angle of diffraction of 2θ montmorillonite from 3 6°. in figure 4 (g) the entry of organometallic compound is not only in 1 layer, but in other layers as well. therefore, the results of the xrd characterization data can be stated that in the weight ratio of bentonite: organometallic compound (1: 3) is more optimally intercalated. to be able to demonstrate the optimal intercalation results, another process of characterization was conducted using xrf analysis (x-ray fluorescence). identification of natural bentonite and bentonite intercalated organometallic compounds [fe3o(oocc6h5)6(h2o)3] (no3)∙nh2o using x-ray fluorescence sinar-x (xrf) characterization using xrf aims to look at the metal oxide compositions contained in natural bentonite, activated bentonite and intercalated bentonite with organometallic compound in the ratio (1: 1), (1: 2), (1: 3) and (1: 4 ). the results data of xrf analysis is presented in table 3. in table 3 it is seen that natural bentonite is composed of montmorillonite mineral containing silica and alumina which yield percentage amount of al2o3 and sio2 metal oxides of 17% and 43.6%. other measured metal oxides are p2o5 with a percentage of 0.71%, k2o with a percentage of 0.2%. composition of cao with percentage as much as 0.99%, tio2 with percentage 1.87%, v2o5 with percentage 0.11%, cr2o3 with percentage 33.39%, nio with percentage 0.87%, cuo with percentage 0.15% zno with a percentage of 0.09%, re2o7 with 0.11% percentage, and eu2o3 with 0.2%. with the activation of natural bentonite causes the value of metal oxide content decreases. this is in accordance with the activation purpose of removing impurities on bentonite in the form of small metals. activation of the first bentonite by heating at 400oc indicates that some oxides are decreased, as cao decreases its percentage to 0.92%, v2o5 to 0.07%. while other metal oxides have the same percentage as natural bentonite despite the presence of binding metal oxides, such as tio2 to 1.91%, cr2o3 to 0.11%, mn to 0.19%, fe2o3 to 33.57%. this reduction in metal oxide content due to metal oxides on the bentonite is already lost oxide activation due to heating to form other inorganic substances. tabel 2.metal oxide composition using xrf bao: natural bentonite ; b400: physical activation at 400 oc; baa: chemical activation using sulfuric acid; ha1: (1:1); hb2: (1:2); hc3: (1:3); hd4: (1:4). the second activation of natural bentonite by adding sulfuric acid. this causes a decrease in the percentage of metal oxide. the decrease in the percentage of metal oxide on the acidified bentonite is shown in table 2. the decrease of metal oxide is al2o3 to 11%, sio2 to 28.8%, k2o to 0.19%, tio2 to 1.73%, v2o5 to 0.06%, cr2o3 becomes 0.06%, mn to 0.17%, fe2o3 to 29.2%, nio to 0.88%, and cuo to 0.15%. furthermore, to determine the results of intercalation of bentonite with organometallic compound [fe3o(oocc6h5)6(h2o)3](no3) ∙nh2o in the ratio (1: 1), (1: 2), (1: 3) and (1: 4) are performed by observing the oxide content, especially the al2o3 and sio2 metal oxides located on the inseminating montmorillonite layer. then the intercalation compound content of organometallic compound causes the metal oxide of fe2o3 to increase. the result of xrf analysis in table 2 shows that the ratio of weight (1: 2) and (1: 3) has significant decrease of al2o3, al2o3 has a percentage of 8.2%, utami et al. / science and technology indonesia 1(1) 2016:20-24 @2016 published under the terms of the cc by nc sa 4.0 license 24 sio2 has a percentage of 23.9% and an increase of fe2o3 to 63, 89%. however, in the weight ratio (1: 3) the metal oxide decreased al2o3 to 6.2%, sio2 had a percentage of 18.7% and the increase of fe2o3 to 71.75%. therefore, the result of bentonite intercalation of the optimal organometallic compound is shown in the ratio (1: 3) because it contains a lot of fe2o3 composition as well as decreasing the good percentage of each treatment. conclusion bentonite intercalated organometallic compounds [fe3o(oocc6h5)6(h2o)3](no3) showed optimal intercalation process in the weight ratio (1: 3). characterization using xrd showed an diffraction at 5.2 ° having a basal spacing of 16.8 ǻ. further characterization using xrf showed the intercalation (1: 3) has percentage 12.75% of metal oxide. acknowledgement we thank to prof. aldes lesbani for fruitful disscusion related with this research. hpu and dms thanks to integrated research laboratory, graduate school, sriwijaya university for laboratory equipment and support. references abderrazek, k., najoua, f.s. and srasra, e., 2016. synthesis and characterization of [zn–al] ldh: study of the effect of calcination on the photocatalytic activity. applied clay science, 119, 229–235. bertella, f. and pergher, s.b.c., 2015. pillaring of bentonite clay with al and co. microporous and mesoporous materials, 2011, 116–123 brindley, w., and brown, g. 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inorganic chemistry, 51(2), 775–777. yang, r.t., 1999, structual aspects of metal oxide pillared sheet silicates, j. chem. soc. faraday trans zhu, h.,m and vansant,.e.e., 2008. corelation beetween the micropore structure and the adsorption of benzone in plillared clays, separtion technology. amsterdam. 466: 153158. science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2016) 16-19 article http://sciencetechindonesia.com @2016 published under the terms of the cc by nc sa 4.0 license 16 mg/al double layer hydroxides: intercalation with h3[α-pw12o40]•nh2o yulizah hanifah1,* and neza rahayu palapa1 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail : yulizahanifah@gmail.com abstract it has been done the intercalation of polyoxometalate h3[α-pw12o40]•nh2o on mg-al double layer hydroxide by comparison weight ratio of double layer hydroxides : polyoxometalate h3[α-pw12o40]•nh2o, i.e: 1:1, 1:2, 1:3 and 1: 4. the product of intercalated double layer hydroxide was characterized using ft-ir spectrophotometer, xrd, and tg-dta analysis. the spectrophotometer results of ft-ir shown the process of intercalation was not optimum for every weight ratio. characterization using xrd showed the process of intercalation was optimum at a ratio 2:1 that indicated at the area of 11,12o, 22,85o and 34,5o as double layer hydroxide and at the area of 60-63o showed the double layer hydroxide has intercalated with polyoxometalate. the characterization results using tgdta analysis at the comparison 2:1 showed loss of oh in the layer at 170 to 220°c and for the decomposition of polyoxometalate h3[α-pw12o40]•nh2o at 300 to 400°c. keywords: double layer hydroxide, intercalation, polyoxometalate h3[α-pw12o40]·nh2o introduction layered materials or clay of inorganic minerals are found in nature and can also be synthesized in the laboratory (abderrazek et al, 2016). layered material is used as a catalyst, adsorbent, sensor, membrane or ion exchange. as adsorbent, a layered material used for aditive adsorption on vegetable oil (franchi et al, 1991) as well as its application for the control of contamination of metal ions or organic compounds in the environment. the advantages of this double layer hydroxide have a great anion exchange properties and can be exchanged for various other anions (beaudot et al, 2004). the general formula for double layer hydroxide is [m2+(1-x)m3+x(oh)2](an-)x/n•nh2o which in that positive charges are balanced by the interlayer anions such as cl-, no3and co3 (guo et al, 2014). however, the use of these layered materials still has small surface area constraints and narrow layer spacing due to the small exchange ions which are generally alkali and alkaline earth metal ions (goodarzi et al, 2016). double layer hydroxide still needs to be modified to increase its surface area and majority modifications made to this research are through intercalation of layered materials with atoms, molecules and complex compounds using ion exchange methods. the purpose of this intercalation process is expected to produce double layer hydroxide intercalated macro anion that automatically increasing interlayer so it can be used as adsorbent or catalyst. the macro anion is used polyoxometalate keggin type h3[α-pw12o40]·nh2o. the intercalated macro anion of double layer hydroxide causes the loss of the ohanion that located on the layer so it is expected to increase the distance between layers of the double layer hydroxide. article history submitted: 2 june 2016 accepted: 5 august 2016 doi: 10.26554/sti.2016.1.1.16-19 in this research, synthesis and characterization of double layer hydroxide, polyoxometalate h3[α-pw12o40]·nh2o and double layer hydroxide intercalated polyoxometalate h3[αpw12o40]·nh2o has been done. characterization has been conducted using fourier transform infra red (ft-ir), x-ray diffractometer (xrd) and thermo gravimetric-differential thermal analysis (tg-dta). experimental section material and methods double layer hydroxide intercalated with h3[αpw12o40]·nh2o was performed by ion exchanged method. characterization of the synthesized compounds was performed by different techniques such as ftir, x-ray diffractometer (xrd). xrd was performed using shimadzu lab x-type 6000 to determine the surface area before and after intercalated. the tg-dta analysis of double layer hydroxide intercalated polyoxometalate h3[α-pw12o40]·nh2o was evaluated using shimadzu tg / dta 60a analyzer from 20°c to 800 °c. preparation of mg-al ldh and h3[α-pw12o40]·nh2o composite preparation of mg-al ldh mg-al ldh was synthesized by mixing 64.01 g of mg(no3)2.6h2o (2 mol) and 46.64 g of al(no3)3.9h2o (1 mol) were dissolved in 150 ml of aquadest (solution a). 10.00 g of naoh and 26.62 g of naco3 was poured into 150 ml aquadest (solution b). solution a is added to solution b and stirred gradually with the addition of aquadest of 100 ml and a ph adjusted from 9 to 10 to form sediment. the sediment is dried into oven at 80 °c and ready to be characterized using ftir spectroscopy and xrd analysis. preparation of polyoxometalate h3[α-pw12o40]·nh2o composites 125 g of sodium tungstate and 20 g of sodium phosphate were mixed with 187.5 ml of boiling water in 500 ml of a glass hanifah et al. / science and technology indonesia 1(1) 2016:16-19 @2016 published under the terms of the cc by nc sa 4.0 license 17 beaker. 100 ml of hydrochloric acid is added dropwise to the mixture and stirred using a magnetic stirrer. the stirring process is continuous until all the solid dissolve. the phosphotungstate acid will begin to separate when half of the hydrochloric acid is added then the resulting solution becomes clear and cooled. a 75 ml of diethyl ether cold solution was added and then extracted. after extraction process obtained three layers, the solution separated and taken from the bottom layer. the lowest layer was evaporate using a rotary evaporator to obtain white solid that is h3[α-pw12o40]·nh2o. characterization of h3[αpw12o40]·nh2o was performed using ft-ir spectrophotometer and xrd analysis. intercalation of ldh-pom intercalation process of double layer hydroxides by polyoxometalate h3[α-pw12o40]·nh2o by ion exchange method was carried out by preparing 1 g of h3[α-pw12o40]·nh2o (solution a) mixed with 50 ml of distilled water, and 2 g of double layer hydroxide was added with 25 ml naoh 1 m (solution b). solution a and solution b are then mixed rapidly under conditions given n2 gas for 24 hours. then the suspension is cooled and the product is washed with water and dried at room temperature. structural analysis, the thermal stability of the inserted product is carried out using xrd, ftir and tg-dta. results and discussion characterization of ldh-pom mg-al ldh and ldh-pom using comparison 1:1, 1:2, 1:3 and 2:1. the characterization of the ft-ir spectra aims to identify the functional groups formed as shown in figure1. figure 1. ft-ir spectra of (a) double layer hydroxide (b) polyoxometalate h3[α-pw12o40]·nh2o (c) intercalation ldhpom with a rasio 1: 1 (d) 1: 2 (e) 1: 3 (f) 2: 1. the ft-ir spectrum of ldh is presented in figure 1. at 671 and 1381 cm-1 which are indicated nitrate bend and the symmetric stretch of nitrate (handayani, 2013). on the other hand, the characteristic peak of ldh at 601, 408 cm-1 which are al-o and mg-o vibration. figure 1b shows the peaks of the functional group of polyoxometalateh3[α-pw12o40]·nh2o. the characteristic of polyoxometalate is shown at 802, 894, 987 and 1080 cm-1 which are related to the w-oc-w, w-ob-w, w=o, and p-o. figure 1c in comparison ldh-pom (1:1) shows the presence of a vibrational peak at 3479.5 cm-1 which are related to o-h group vibration. the absorption band at 1635.6 cm-1 is indicated buckling of the adsorbed o-h group on interlayer and absorbing bands at 1381 cm-1 showing symmetrical nitrate synthesis yield of double layer hydroxide. the three vertices of this vibration are also shown in the ft-ir spectrum of figure 1d (1:2), 1e (1:3) and 1f (2:1). these three peaks indicate the presence of double layer hydroxide material. the differences presented based on the ft-ir spectrum in figure 1 are shown by the presence of polyoxometalate. figure 1c show a vibration peak for a polyoxometalate at 663 cm-1 which is a vibration of w-oc-w. figure 1d shows the peak vibration of polyoxometalate at 887-810, 987 and 1080 cm-1 which are related to the w-oc-w, w-o, and p-o vibration. in figure 1e at 1018 and 786 cm-1 are related w-oc-w and p-o vibration. whereas in figure 1 f shows the existence of polyoxometalate at 671 cm-1 is w-oc-w vibration. characterization of ldh, polyoxometalate h3[αpw12o40]·nh2o and intercalation result using x-ray difraction polyoxometalate h3[α-pw12o40]·nh2o characterization using xrd. the diffraction is shown in figure 2. figure 2. x-ray diffraction of polyoxometalate h3[αpw12o40]·nh2o figure 2 shows the x-ray diffraction patterns of h3[αpw12o40]·nh2o with the principal regions of 2θ ie 6-10o, 1520o, 22-25o and 35-45o wherein those diffractions are characteristic for crystalline polyoxometalate h3[αpw12o40]·nh2o (zhang et al, 2012). the results of the measurement analysis are known to have the largest peaks appear in regions 7o and 37–45o. the presence of diffraction patterns that appear in the 2θ region below 10o denotes the typical peak of the polyoxometalate mo6 where m is tungsten and has high crystallinity. polyoxometalate h3[αpw12o40]·nh2o are subsequently intercalated into a double layer hydroxide material which aims to increase the distance 2θ (degree) wavenumber (cm-1) t (% ) hanifah et al. / science and technology indonesia 1(1) 2016:16-19 @2016 published under the terms of the cc by nc sa 4.0 license 18 between the double layer hydroxide layers. the double layer hydroxide material and the intercalated double layer hydroxide are presented in figure 3. from the figure3a, double layer hydroxide diffraction was showing the highest peak at 27o-29o which is demonstrated double layer hydroxide material. figure 3b shows the interfraction pattern of double layer hydroxide material intercalated polyoxometalate with the ratio (1: 1) there is the highest diffraction peak that is in the area at 10,8o, 22,4o and 8,9o. figure 3b shows diffraction peak at 10.8°, 22.4o and 34.1° are having relatively high crystallinity (kloprogge et al 1999). according, to wiyantoko (2015), these three diffraction shows the properties of double-layer hydroxide materials, which have layered structures with intensity are 340, 156 and 101. the regions appearing at 60-63o indicate the presence of anions in the interlayer of the layered material. based on this data can be expressed comparison compared to the ratio in (1: 1), (1: 3) and (2: 1). figure 3. diffractogram xrd (a) double layer hydroxide (b) intercalation of double layered hydroxide with polyoxometalate with a rasio of 1: 1 (c) 1: 2 (d) 1: 3 (e) 2: 1. figure 3c shows the different angles of the diffraction form showing the existence of double layer hydroxide material at 2θ = 10.9o. 22.88o and 34.4o and indicating the diffraction of the success of the anions, which is presented in a double layer hydroxide material at 60.4o and 61.7o with a relatively smaller intensity than the diffraction fig (1: 1) and (2: 1). figure 3 d (1:1) is successfully synthesized wherein the polyoxometalate enters the interlayer of the double layer hydroxide material. figure 3e also shows the existence of double layer hydroxide material at 2θ = 11.12o, 22.85o and 34.5o which have greater intensity are 518, 192 and 133 than on comparison (1: 1), (1: 2) and (1: 3). the diffraction shows the success of intercalation process of double layer hydroxide material with polyoxometalate at 2θ=60,4o and 61,7o which has greater intensity than on (1: 1), (1: 2) and (1: 3) are 71 and 72. characterization of ldh and ldh intercalated polyoxometalate h3[α-pw12o40]·nh2o using tg-dta double layer hydroxide obtain was then characterized using tg-dta analysis. the purpose of thermogravimetric analyzer (tga) analysis was used to record changes in sample weight as a function of temperature and differential thermal analyzer (dta) to detect changes in the heat content. the tg-dta analysis of the double layer hydroxide has a thermogram pattern as shown in figure 4. figure 4 shows the double layer hydroxide decomposed with the loss of water molecules at 77-102°c with weight loss about 23% (xie, 2006). from the thermogram could be seen a sharp peak dta at a temperature of 77-102°c. figure 4. termogram of double layer hydroxide material at 300-320°c, which is the decomposition of the oh group of the interlayer material of the double layer hydroxide material with a loss of weight is 15.22% indicated on the red line ie the weight loss. the endothermic peak at 308 °c indicates loss of carbonate (li, et al. 2013). according to yu (2009), dehydroxylation process and loss of mg/al-co3ions at the endothermic peak are seen at temperatures around 220oc. the endothermic peak at 650-750oc indicates a double layer hydroxide material decomposition in the presence of an endothermic peak marked by loss of carbonate ions attached to mg2+ dan al3+ with a weight loss about 22.89% (lin et al, 2001). the intercalation of double layer hydroxide with polyoxometalate h3[α-pw12o40]·nh2o by weight ratio (2: 1) has a thermogram pattern as in figure 5. figure 5. thermogram intercalation result of double hydroxy with polyoxometalate h3[α-pw12o40]·nh2o hanifah et al. / science and technology indonesia 1(1) 2016:16-19 @2016 published under the terms of the cc by nc sa 4.0 license 19 figure 5 shows the presence of three endothermic peaks. the first endothermic peak at a temperature of 20-90 oc is due to the loss of water molecules. at the second endothermic peak at temperatures of 170-220 oc is demonstrated the decomposition marked by the loss of the oh group present in the interlayer (zhang et al, 2012). the third endothermic peak is at a temperature of 300-400 °c which is a decomposition of a polyoxometalate h3[αpw12o40]·nh2o with loss of hydrogen bonds between h3[αpw12o40]·nh2o with hydrogen ions (khozhevnikov, 2012). conclusion intercalation double layer hydroxide with polyoxometalate h3[α-pw12o40]•nh2o in the optimal ratio (2: 1) characterized using ft-ir spectrophotometer has not demonstrated the success of the optimal intercalation process and the characterization using xrd indicates a gallery height of 7.8 ǻ before the process of intercalation to 7.9 ǻ after the intercalation process. further characterization using tg-dta analysis showed oh loss in the layer at temperature 170-220oc while for decomposition of polyoxometalate h3[αpw12o40]•nh2o was at 300-400oc. references abderrazek, k., najouna, f.s., and srasra, e. 2016. synthesis and characterization of [zn-al] ldh: study of the effect of calcination on the 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infrared and raman spectroscopic study of the local structure of mg-, ni-, and cohydrotalcite. journal of solid state chemistry. 146: 506-515. kozhevniov, i.v., 2002. catalysts for fine chemical synthesis catalysis by polyoxometalate. uk: university of liverpool. li, shou., bai, z., and choo, d., 2013. characterization and friction performance of zn/mg/al-co3 double layer hydroxides. applied surface science. 284: 7-12. lin, xu., chang-wen, hu., and en-bu, w. 1997. advance in study of a new class of pillared layered microporous material polyoxometalate type hydrotalcite-like catalysis. journal of natural gas chemistry. 6(2): 155. wiyantoko, b., kurniawati, p., and fatimah. 2015. synthesis and characterization of hydrotalcite at different mg/al molar ratio. procedia chemistry. 17: 21-26. xie, w., reng, hong., chem, l., 2006. calcined mg/al hydrotalcite as solid based catalysis for methanolysis of soybean oil. journal of molecular catalysis. 246: 24-32. yang, s., huang, y., and li yu., 2011. catalytic application of h4siw12o40/sio2 in synthesis of acetals and ketals. advanced materials research, 284-286: 2374-2379. yu, s., shan, r., yang, m and du, b. 2015. highly efficient removal of three red dyes by adsorption onto mg-al-layered double hydroxide. journal of industrial and engineering chemistry. 21: 561-568. zhang, y., su, j., pang, q., and qu, w. 2012. polyoxometalate intercalated mgal double layer hydroxide and its photocatalytic performance. journal of material science and engineering. 2(1):59-63. zhang, s., chen, l., liu, hong., and yang, y. 2012. the design of h3pw12o40/tio2 and ag/h3pw12o40/tio2 filmcoated optical fiber photoreactor for the degradation of aqueous rhodamine b and 4-nitrophenol under simulated sunlight irradiation. journal of chemical engineering. 200: 300-309. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper increasing the solubility and anti-inflammatory activity of curcumin by cocrystallization yudi wicaksono1*, kuni zu’aimah barikah1, amanda della yudatama1, havidhatul maulia1, nuri2, dwi setyawan3 1api and excipient research group, faculty of pharmacy, university of jember, jember, 68121, indonesia2bio-active natural product development research group, faculty of pharmacy, university of jember, jember, 68121, indonesia3faculty of pharmacy, airlangga university, surabaya, 60286, indonesia *corresponding author: yudi.farmasi@unej.ac.id abstractcurcumin (cur) is a polyphenolic compound that exhibits potent anti-inflammatory activity. however, only a tiny amount of cur isabsorbed during oral administration, which is because cur is difficult to dissolve in water. the aim of the research was to increase thesolubility of cur through the cocrystallization technique using isonicotinamide coformer (inic) by solvent evaporation. cocrystalcharacterization was carried out using a powder x-ray diffractometer (pxrd), a differential scanning calorimeter (dsc), a fouriertransform infrared spectrometer (ftir), and a scanning electron microscope (sem). solubility was evaluated using the shakingmethod, while the anti-inflammatory activity test was carried out using the carrageenan-induced mouse leg edema method. theresulting cur-inic (1:1) cocrystal has a diffractogram with new diffraction peaks of 2\ at 15.00, 16.22, and 22.89◦ compared tothe individual diffractograms of cur and inic. in the cocrystal, cur and inic form intermolecular interactions of hydrogen bonds,resulting in a new solid phase with a melting point of 160.1◦c. the solubility of the cur-inic cocrystal in water was 73.1±0.23 `g/ml,which increased 14 times compared to the solubility of initial cur, which was only 5.05±0.07 `g/ml. the cur-inic cocrystalshowed a percentage of edema inhibition in mice (5 hours) 130% more potent than that of initial cur. therefore, cur-inic cocrystalscan be used to improve cur solubility to obtain more excellent anti-inflammatory effects. keywordscurcumin, solubility, anti-inflammatory, cocrystals, isonicotinamide received: 23 january 2023, accepted: 1 july 2023 https://doi.org/10.26554/sti.2023.8.3.501-508 1. introduction curcumin (cur) is a polyphenol compound with various biological activities such as anti-inflammatory, antioxidant, and anti-tumor (sohn et al., 2021) . cur has been shown to have potent anti-inflammatory effects in various inflammatory diseases in clinical trials. the anti-inflammatory effect of cur is considered to be the basis of various pharmacological activities which play an essential role in the treatment of various diseases. therefore, cur is considered one of the natural compounds with tremendous potential in treating diseases (peng et al., 2021) . however, until now, the use of cur as a therapeutic drug is still constrained by pharmacokinetics (sohn et al., 2021; tabanelli et al., 2021; hakim et al., 2021). cur given orally is very little absorbed in the gastrointestinal tract, so its bioavailability to achieve pharmacological effects is less than 1% (suresh and nangia, 2018; peng et al., 2021). one reason for the low absorption of cur in the gastrointestinal tract is that cur is very slightly soluble in water (<8 mg/l) (suresh and nangia, 2018; zhang et al., 2023). the structure of the cur molecule has two aromatic ring systems with omethoxy phenolic groups, connected by seven carbon linkers consisting of an 𝛼, 𝛽 -unsaturated 𝛽 -diketone groups so that it is hydrophobic and difficult to dissolve in water (priyadarsini, 2014; suresh and nangia, 2018). various techniques have been used to increase the solubility of active pharmaceutical ingredients (api), one of which is the formation of multicomponent solids (sohn et al., 2021; sanphui and bolla, 2018; fang et al., 2021). a multicomponent solid is formed from an api and a coformer, resulting in a new solid phase (haneef and chadha, 2017; palanisamy et al., 2019). the api can be prepared into a multicomponent solid with certain coformer so the solubility can increase (haneef and chadha, 2017; chavan and shastri, 2018; wicaksono et al., 2021; anggraini et al., 2022). cocrystallization is an exciting and attractive technique for forming multicomponent solids to increase the solubility of api (karimi-jafari et al., 2018) . cocrystals are multicomponent https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.501-508&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.501-508 wicaksono et. al. science and technology indonesia, 8 (2023) 501-508 solids formed by two or more types of molecules with noncovalent interactions such as hydrogen bonds, van der waals interactions, and 𝜙-𝜙 interactions (haneef and chadha, 2017; sanphui and bolla, 2018; wicaksono et al., 2020). cocrystals can increase the solubility of crystalline api through the mechanism of decreasing crystal lattice energy so that api in crystalline solids is more easily hydrated by water molecules (ozaki et al., 2014; docherty et al., 2015; bergström and larsson, 2018). the increased solubility of api by cocrystallization has thermodynamic advantages because its formation is usually spontaneous, the resulting solid is energetically more stable than its pure form, and the cocrystal structure is separate from the constituent components (maheshwari et al., 2009; fischer et al., 2016; taylor and day, 2018). another critical advantage of cocrystallization is that the api and coformer interact through non-covalent interactions so that they do not change the molecular structure and pharmacological activity of the api (haneef et al., 2021; guo et al., 2021; acebedo-martínez et al., 2022). the aim of this research is to increase the solubility of cur by cocrystallization technique so that cur becomes more easily absorbed in the gastrointestinal tract and has greater bioavailability to achieve therapeutic effects as an anti-inflammatory (suresh and nangia, 2018; gao et al., 2019; chen et al., 2020; peng et al., 2021). the cur molecule has a beta-diketol group and two phenolic groups, which are known to be highly reactive in forming intermolecular interactions of hydrogen bonds (suresh and nangia, 2018; sanphui and bolla, 2018; he et al., 2019). cur and n-acetylcysteine coformer using the supercritical solvent method indicated the cocrystal formation with higher solubility than the initial cur (paulazzi et al., 2022) . cur can also form cocrystals with ascorbic acid coformer by solvent evaporation, where the solubility can also increase significantly compared to the initial cur (pantwalawalkar et al., 2021) . cur cocrystallization was carried out with isonicotinamide (inic) as a coformer by solvent evaporation. inic was chosen as a coformer because structurally, it has amide groups and furan rings, so it has the potential to form short-strong hydrogen bonds with hydroxyl groups on cur molecules (kerr et al., 2015) . in addition, inic is easily soluble in water, so it is likely to increase the solubility of the resulting cocrystal (suresh and nangia, 2018) . 2. experimental section 2.1 chemicals and equipment the chemicals used were cur (tokyo chemical industry co., ltd.), inic (sigma-aldrich®), cmc-na (merck®), carrageenan (sigma-aldrich®), and methanol (pt. smart lab indonesia). the experimental animals used were male balb/c rats (20-30 g) obtained from the faculty of dentistry university of jember. the research equipment used was a powder x-ray diffractometer (pxrd), a differential scanning calorimeter (dsc), a fourier-transform infrared spectrometer (ftir), a scanning electron microscope (sem) equipped with an ion sputter, a uv-vis spectrophotometer, a magnetic stirrer, and an orbit shaker. 2.2 methods 2.2.1 cocrystallization of cur-inic cur and inic in an equimolar ratio (1:1) were put into a beaker (total weight 1 g). 10 ml of methanol was added to the beaker glass, then tightly closed with aluminum foil. the mixture in the beaker glass was then stirred with a magnetic stirrer (thermo fisher sp88857107) at 300 rpm (30◦c) for 30 minutes, and after that, the aluminum foil covering the beaker glass was given small holes. the beaker was gently shaken with an orbital shaker (thermo scientific) at 125 rpm (30◦c) so that the solvent evaporated, leaving the solid. the dry solids were then reduced with a mortar and sieved through an 80-mesh sieve. 2.2.2 characterization with pxrd tests were carried out with a panalytical x’pert pro diffractometer using cuk𝛼1 (_ =1.542 å) as a radiation source. scanning at an angle of 2 𝛽 with a speed of 10◦/min uses a size range of 5-50◦ with a voltage of 40 kv and a current of 30 ma. 2.2.3 characterization with dsc the equipment used was thermo plus evo dsc 8230. the sample (approximately 2 mg) was put into an airtight aluminum pan and closed tightly with a press apparatus. the sample is then placed on the sample board on the dsc. the dsc test was carried out under dry airflow conditions with a temperature range of 30-200◦c and a heating rate of 10◦c/minute. 2.2.4 characterization with ftir ftir spectra were determined using a fourier transform infrared spectrometer (thermo scientific nicolet is10). a sample of about 5 mg was sprinkled evenly on the board from the equipment, and then measurements were taken using a resolution of 4 cm−1 at a wave number of 4000-600 cm−1. 2.2.5 characterization with sem the equipment used is a hitachi tm 3000 with an ion sputter (hitachi e-1045). the sample powder was placed evenly on the sample board, then coated with platinum using an ion sputter for 20 seconds. then the samples were observed using sem at a voltage of 15 kv and a current of 30 ma with the appropriate magnification. 2.2.6 solubility test the solubility test using an excess sample (about 20 mg) was carried out by shaking method. samples were containerized with erlenmeyer, and added 10 ml of distilled water. then the erlenmeyer was tightly closed using aluminum foil and shaken for 24 hours using an orbital shaker (thermo scientific) at 175 rpm (30◦c). the supernatant was filtered (0.45 microns) and diluted with sufficient methanol, and then the cur level was measured using a uv-vis spectrophotometer at _ 425 nm (thermo scientific genesys 20). the solubility test was repeated thrice (hanif et al., 2022) . © 2023 the authors. page 502 of 508 wicaksono et. al. science and technology indonesia, 8 (2023) 501-508 2.2.7 evaluation of anti-inflammatory activity anti-inflammatory activity was evaluated using the mice-carrageenan-induced paw edema method (gupta et al., 2015; ahangar et al., 2019; yimer et al., 2020). the experimental animal treatment procedure was approved by the research ethics committee of the university of jember (no. 1360/un25.8/k epk/dl/2021). male balb/c mice (20-30 g) were grouped into three (6 mice each): the control group (i), the pure cur group (ii), and the cur-inic group (iii) (ma et al., 2019; zhnyakina et al., 2020). mice were acclimatized for seven days by being given water and a standard diet ad libitum under standard conditions. before being treated, the mice fasted for 12 hours (no diet but still given water). treatment was given by gavage, 0.5% cmc-na suspension (0.1 ml/kg bw) to group i (control group), 0.5% cmc na suspension containing cur (dose 200 mg/kg bw) to group ii, and 0.5% cmc na suspension containing cur-inic (dose equivalent to cur of 200 mg/kg bw) to group iii. after administration of the suspension, the thickness of the right hind paw of the mice was measured with a caliper (t0). one hour after administration of the suspension, the right hind paw of the mice (sub-plantar area) was injected with 0.01 ml of 1% carrageenan. furthermore, after 0.5, 1, 2, 3, 4, and 5 hours of 1% carrageenan treatment, the thickness of the right hind paw of the mice has measured again (tt). the changes in the thickness of the paw (δ) were calculated as the difference between the paw thickness after injection (tt) and the paw thickness before injection (t0). the percentage of edema inhibition (5 hours after injection of 1% carrageenan) was calculated by the formula: % edema inhibition = [(δcontrol-δtreatment)/δcontrol] × 100 (gupta et al., 2015) . 2.2.8 statistical analysis statistical analysis was carried out using one-way anova and bonferroni post hoc test on the spss 22.0 software program. differences in data between sample groups were considered significant if the p-value<0.05. 3. results and discussion 3.1 pxrd diffractogram the pxrd diffractograms of cur, inic, and cur-inic are shown in figure 1. the pxrd diffractograms of cur have shown sharp peaks at 7.75, 8.72, 15.72, 17.06, and 20.98◦, indicating similarity to the diffractogram of the cur polymorph form 1, which has a monoclinic crystal structure (sanphui et al., 2011) . inic has shown a diffractogram with sharp peaks at 7.59, 20.60, 25.66, 26.38, and 30.74◦, which indicates agreement with the literature (liu et al., 2021) . the solid cur-inic has a pxrd diffractogram with a new pattern different from the cur and inic diffractograms. new diffraction peaks appear on the cur-inc diffractogram, namely at 15.00, 16.22, and 22.89◦. the presence of new peaks on the cur-inic diffractogram indicates that the solid cur-inic is not a physical mixture of cur and inic but is a new crystalline solid with a different structure resulting from figure 1. pxrd difractogram of (a) cur, (b) inic, and (c) cur-inic the interaction between cur and inic (pantwalawalkar et al., 2021) . 3.2 dsc thermogram the dsc thermograms of cur, inic, and cur-inic are shown in figure 2. the thermogram of cur shows an endothermic peak at 186.1◦c (δh = 119.25 j/g), while the thermogram of inic also shows an endothermic peak at 156.9◦c (δh = 175.24 j/g). the temperatures of the endothermic peaks on the cur and inic thermograms are correlated with melting points that agree with the literature ketkar et al. (2016) and abdelkader et al. (2022) . figure 2. dsc thermogram of (a) cur, (b) inic, and (c) cur-inic on the cur-inic thermogram, two endothermic peaks appear, namely at 149.2◦c (δh = 32.742 j/g) and 160.1◦c (δh = 76.344 j/g). the first endothermic peak (149.2◦c) represents the melting of the eutectic mixture, while the second endothermic peak (160.1◦c) represents the melting of the cur-inic cocrystal (pantwalawalkar et al., 2021) . the cur© 2023 the authors. page 503 of 508 wicaksono et. al. science and technology indonesia, 8 (2023) 501-508 inic cocrystal solid showed melting at temperatures between the melting temperatures of cur and inic, indicating that cur and inic molecules formed intermolecular interactions in cur-inic solids with a different arrangement compared to cur and inic, resulting in a new crystalline solid phase (satapathy et al., 2021) . the molecular arrangement of cur-inic cocrystal solids determines the formation of crystal packing and crystal lattice energy in cur-inic cocrystal solids (kilinkissa et al., 2020; volodin et al., 2019; ejarque et al., 2021). packing and crystal lattice energy affect the melting temperature of the solids, and cocrystals generally have melting temperatures between those of their constituents (qiao et al., 2011; salahinejad et al., 2013; gamidi et al., 2018). the curinic cocrystal exhibits a lower melting point than pure cur solids because the inic molecules in the cocrystal structure are thought to produce a repeating pattern of the crystal lattice with more significant variations in intermolecular forces, thereby lowering the melting point (salahinejad et al., 2013; gamidi et al., 2018). the pattern of the thermogram and melting point of the cur-inic cocrystal shows similarities to the cur-ascorbic acid cocrystal (pantwalawalkar et al., 2021) . 3.3 ftir spectra the ftir spectra of cur, inic, and cur-inic are shown in figure 3. the cur spectra showed an absorption peak at 3500 cm−1, indicating stretching vibrations of o-h phenolic, 1626 cm−1 associated with stretching vibrations of c=c and c=o, 1601 cm−1 associated with c=c stretching vibrations of the aromatic ring, 1505 cm−1 associated with vibrations of c=o, 1262 cm−1 associated with vibrations of aromatic c-o (enol groups), and 1026 cm−1 associated with vibrations of c-o-c group (sharma et al., 2022) . inic has a spectrum with absorption peaks at 3363 and 3177 cm−1, showing stretching vibrations of asymmetric and asymmetric n-h, 1657 cm−1 associated with stretching vibrations of c=o amide, 1621 cm−1 associated with bending vibrations of amide n-h, and 1408 cm−1 is related to the stretching vibrations of c-n amide (ferreira et al., 2022) . in the cur-inic spectra, it appears as a combination of the absorption peaks from the cur and inic spectra. however, there were shifts in wave number values at several absorption peaks compared to the individual absorption peaks of cur and inic. the cur absorption peaks in the cur-inic spectra, which showed a shift, were 3500 to 3507 cm−1, 1262 to 1275 cm−1, and 1026 to 985 cm−1. meanwhile, the absorption peaks of inic in the cur-inic spectra showed a shift, 3363 to 3329 cm−1, 1657 to 1679 cm−1, 1621 to 1626 cm−1, and 1408 to 1413 cm−1. the absorption peaks of cur-inic, which are experiencing a shift, are the absorption peaks of the donor and acceptor groups of hydrogen bonds. the shift of the absorption peaks indicates that in curinic, there has been a hydrogen bonding interaction involving the phenolic o-h, aromatic c-o (enol), and c-o-c groups of the cur molecules with the c=o, n-h, and c-n groups of the inic molecules (pantwalawalkar et al., 2021) . 3.4 sem images sem is useful for analyzing the morphology and surface topography of materials. sem images of cur, inic, and curinic are shown in figure 4. sem images have shown that the shape of the cur particles is a rectangular plate with a smooth surface, while the shape of the inic particles is a rod with a wavy surface. sem images of cur-inic particles have shown a different shape and appearance than cur and inic particles. cur-inic particles have an irregular shape resulting from aggregating a set of particles, and there are no visible traces of cur and inic particles. the aggregates of cur-inic particles form a morphology and surface topography with a hollow structure indicating a larger surface area. the characteristics of particles with a hollow structure generally have more excellent solubility properties than particles with a dense structure (agarwal et al., 2020; kawano et al., 2021). based on the results of the analysis with pxrd, dsc, ftir, and sem, it was concluded that cur and inic, after preparation, formed a new solid phase with a different molecular arrangement compared to the starting material. the cur and inic molecules in the cur-inic solid form a hydrogen bond interaction, resulting in a new crystal structure. the new crystal structure of the cur-inic cocrystal is indicated in the pxrd diffractogram and ftir spectra. the cur-inic cocrystal shows different thermodynamic and physical properties compared to each constituent material, as shown in the analysis results by dsc and sem. 3.5 solubility the nature of solubility in water is a critical parameter that determines the absorption and bioavailability of an api. cur is poorly soluble in water, so it is difficult to absorb by the gastrointestinal tract, causing its bioavailability to be below 1% (suresh and nangia, 2018; peng et al., 2021). the solubility test results showed that cur had a solubility in water of 5.05±0.07 `g/ml, while the cur-inic cocrystal in the water had a solubility of 73.1±0.23 `g/ml. these results indicated that the cocrystallization of cur-inic has increased the solubility of cur about 14 times. the solubility of a crystalline solid is strongly influenced by its crystal structure and packing, which is related to the crystal lattice energy. crystalline solids with lower lattice energy are made up of molecules bonded with weaker energy, and during the dissolution process, water molecules more easily hydrate them (kuleshova et al., 2013; thakuria et al., 2013). cocrystals are formed from molecules of api and coformer that make up the crystal lattice. molecules of api and coformer in cocrystals interact with non-covalent bonds, such as hydrogen bonds, forming new structures and packings with different lattice energies than the starting materials (guo et al., 2018) . based on the results of the diffractogram, the cur used in this study is a cur polymorph form 1 with a monoclinic structure known to have very low water solubility (sanphui © 2023 the authors. page 504 of 508 wicaksono et. al. science and technology indonesia, 8 (2023) 501-508 figure 3. ftir spectra of (a) cur, (b) inic, and (c) cur-inic figure 4. sem images of (a) cur, (b) inic, and (c) cur-inic (15 kv, ×1000) et al., 2011) . sanphui et al. (2011) modified the cur crystal form and produced cur polymorph forms 2 and 3 with an orthorhombic structure with a higher dissolution rate than cur form 1 (monoclinic). cur in the cur-inic cocrystal exhibited a higher solubility than the initial cur, presumably due to lowering the crystal lattice energy of the cur-inic cocrystal. the intermolecular interaction of inic with cur changes the structure and arrangement of the crystal lattice of cur so that the cocrystal solid formed has a lower lattice energy. cocrystals with lower lattice energy become more easily hydrated by water molecules, increasing their solubility and dissolution rate (ozaki et al., 2014; docherty et al., 2015; bergström and larsson, 2018). 3.6 anti-inflammatory activity changes in the paw thickness of mice after being induced with 1% carrageenan are shown in figure 5. changes in paw thickness indicate the occurrence of edema, which correlates with inflammation. in group i (control), changes in paw thickness occurred after 1% carrageenan administration, increased until the 4th hour, and then decreased at the 5th hour. in groups ii (cur group) and iii (cur-inic group), the paw thickness increased until about 1 hour after 1% carrageenan administration. then the paw thickness decreased until the 5th hour. changes in paw thickness of group i (control) at 1 to 5 hours showed a significant difference (p<0.05) compared to changes in paw thickness from the ii and iii groups. the changes in paw thickness show that administration of 1% carrageenan has induced edema in all groups of mice. in ii and iii groups, there was a significant (p<0.05) decrease in edema (at 1 to 5 hours) compared to group i (control) as a result of the administration of cur and cur-inic cocrystals. the decrease in edema has proven that administering cur and cur-inic cocrystals in ii and iii groups has an anti-inflammatory effect in mice. the percentage of edema inhibition at 5 hours showed that in the ii group (cur), there was an inhibition of edema of © 2023 the authors. page 505 of 508 wicaksono et. al. science and technology indonesia, 8 (2023) 501-508 figure 5. changes of the paw thickness of mice of (a) control group, (b) cur group, and (c) cur-inic group 43.90±2.82%, while in the iii group (cur-inic cocrystal), there was an inhibition of edema of 57.32±2.44%. the percentage of edema inhibition indicates that administration of cur in the form of cur-inic cocrystals (equivalent to cur 200 mg/kg bw) had significantly higher inhibition (130%) of edema than administration of initial cur without cocrystallization. the solubility of the cur-inic cocrystal increased significantly (p<0.05) compared to the solubility of the initial cur. the increase in the solubility of the cur-inic cocrystal is thought to cause the amount of dissolved cur in the digestive tract of mice to be greater than that of group ii (cur). the amount of api dissolved in the digestive tract is generally directly proportional to the api absorbed, which has a pharmacological effect (khames, 2017) . thus, it can be estimated that the increased anti-inflammatory activity in group iii (cur-inic cocrystal) compared to group ii (cur) is due to the increased solubility of cur in the cur-inic cocrystal (granata et al., 2017; he et al., 2019). 4. conclusions cocrystallization of cur with inic coformer produces curinic cocrystals, which exhibit novel crystalline solid characteristics. the pxrd diffractogram of the cur-inic cocrystal has a different pattern of diffraction peaks compared to the individual diffractograms of cur and inic. the molecules of the constituent materials in the cur-inic cocrystal form intermolecular interactions of hydrogen bonds which produce a new solid phase with a melting point of 160.1◦c. the cur-inic cocrystal showed a solubility in water of 73.1±0.23 `g/ml. in comparison, the initial cur showed a solubility of only 5.05±0.07 `g/ml, so the cocrystallization of cur with inic coformer could increase the solubility of cur by 14 times. cur-inic cocrystal showed anti-inflammatory activity in mice 130% stronger than initial cur. thus, increasing the solubility of cur through forming cur-inic cocrystals is an opportunity for further development to obtain cur with a more potent anti-inflammatory effect. 5. acknowledgment the researchers express gratitude to the rector of the university of jember for the funds provided through the idb supporting research grant based on the rector decree number: 14970/un25/kp/2022 and assignment agreement number: 4400/un25.3.1/lt/2022. references abdelkader, h., a. a. fatease, z. fathalla, m. e. shoman, h. a. abou-taleb, and m. a. abourehab (2022). design, preparation and evaluation of supramolecular complexes with curcumin for enhanced cytotoxicity in breast cancer cell lines. pharmaceutics, 14(11); 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(asteraceae). journal of inflammation research, 13; 647– 658 zhang, j., y. zhang, h. wang, w. chen, a. lu, h. li, l. kang, and c. wu (2023). solubilisation and enhanced oral absorption of curcumin using a natural non-nutritive sweetener mogroside v. international journal of nanomedicine, 18; 1031–1045 zhnyakina, l., m. tkachenko, y. v. moshchenskii, and i. munina (2020). differential scanning calorimetry study of the ibuprofen–nicotinamide binary disperse system and the anti-inflammatory activity of one of its secondary eutectics. pharmaceutical chemistry journal, 54; 954–958 © 2023 the authors. page 508 of 508 introduction experimental section chemicals and equipment methods cocrystallization of cur-inic characterization with pxrd characterization with dsc characterization with ftir characterization with sem solubility test evaluation of anti-inflammatory activity statistical analysis results and discussion pxrd diffractogram dsc thermogram ftir spectra sem images solubility anti-inflammatory activity conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper improvement of congo red photodegradation performance through zn/al-tio2 and zn/al-zno preparation nova yuliasari1, amri2, risfidian mohadi1,3, elfita1, aldes lesbani1,3* 1graduate school of mathematics and natural sciences, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia2magister program graduate school of mathematics and natural sciences, universitas sriwijaya, palembang, 30139, indonesia3research center of inorganic materials and coordination complexes, faculty of mathematics and natural sciences, universitas sriwijaya, palembang, 30662, indonesia *corresponding author: aldeslesbani@pps.unsri.ac.id abstractlayered double hydroxide (ldh) is an anionic clay material known to be effective as a catalyst for the photodegradation of dyeorganic pollutants. zn/al ldh was synthesized by coprecipitation then impregnated with metal oxides and calcined at 300◦cto form zn/al-tio2 and zn/al-zno as photodegradation catalysts of congo red (cr). the characterization of the catalysts afterpreparation using sem and uv-drs while the catalyst that have been used in 5 regeneration cycles was characterized by xrd andftir. photodegradation of cr was carried out by optimizing ph, catalyst weight, and time radiation. zn/al ldh which was modifiedinto zn/al-tio2 and znal-zno had a better degradation percentage, rate constant, and stability than zn/al ldh pristine structure.zn/al ldh, zn/al-tio2 and zn/al-zno catalyzed cr photodegradation for 120 minutes with percent degradation 68.39%, 81.24%and 71.09%, respectively. keywordszn/al ldh, congo red, zno, tio2, photodegradation received: 20 june 2022, accepted: 13 september 2022 https://doi.org/10.26554/sti.2022.7.4.449-454 1. introduction pollution problems are often associated with global industrial waste. waters polluted by textile dyeing can account for nearly twenty percent of the pollutants (guzmán-vargas et al., 2016). layered double hydroxide (ldh) has been reported by many studies as a photocatalyst for the degradation of organic pollutants including textile dyes (muhammad and garzali, 2019). ldh is the best clay that is semiconducting, has a cation of 2+ valence at the center of an octahedral of 6 hydroxyl groups and forms lamellar. the cations with valence 2+ are partially substituted by cations with valence 3+ resulting in a positive charge on the layer of the cation structure. negatively charged anions can be intercalated between the structure of the cation layer. ldh materials can be prepared by varying the content of cation elements to produce dierent physical and chemical properties as needed (li et al., 2020; contreras-ruiz et al., 2019). zn/al ldh ldh materials have often been used to degrade pollutants owing to their good semiconductor properties as photocatalysts (li et al., 2020). not a few studies on the degradationoforganicpollutantscatalyzedbyzn/alldh.hydrothermal methods have been used in preparing zn/al-based catalysts, including zn/al-c3n4 (gandamalla et al., 2021), zn/al-tio2 (mourid et al., 2020), zn/al-zno (trujillano et al., 2020), znba/al-zno (elhalil et al., 2018), zn/al-tio2 (aoudjit et al., 2019), zn/al-zno (zhang et al., 2016), and zncu/al (kimetal.,2017) asphotocatalysts in thedegradation of organic pollutants, respectively ciprooxacin, sulfamethoxazole, nitrophenol, caeine, dodecyl sulphate, methylene blue, and orange ii dyes. ldh preparation technique by coprecipitation is often done because it is not expensive and simple to synthesize, this technique includes the deposition of two or more metal ions using a precipitating agent (song et al., 2019). studies have been carried out using the coprecipitation method using urea as a precipitate in the preparation of zn/al ldh-based materials, these studies were as follows: znmn/al (morales-mendoza et al., 2015), znni/al (wang et al., 2014a) and zn/al-tio2 (wang et al., 2014b) which were used in the degradation of chlorophenol,orangegandmethyleneblue, respectively,while zn/alce (suárez-quezada et al., 2016) and zn/alla (tzompantzi et al., 2014) were used for phenol degradation. the coprecipitation method using sodium hydroxide precipitate was carried out in the preparation of znni/al (qi et al., 2018) and znco/al (li et al., 2018) as a catalyst for rhodaminehttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.449-454&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.449-454 yuliasari et. al. science and technology indonesia, 7 (2022) 449-454 b degradation, while zncu/al-tio2 (seftel et al., 2015) in phenol degradation. the studies of coprecipitation technique that used calcination temperatures include the preparation of zn/alga calcined 500◦c (amor et al., 2018), zn/al ldh calcined500◦cand900◦c(abderrazeketal.,2016),zn/al-tio2 calcined 500◦c (hadnadjev-kostic et al., 2017), zn/al ldh calcined 800◦c (huo et al., 2013) which were respectively used during the degradation of methylene blue, preparation of zn/alce calcined 450-900◦c (zhu et al., 2016) and zn/altio2 calcined 500◦c (rudic et al., 2014) as catalysts in the degradation of rhodamine-b and the preparation of zn/alga calcined at 550◦c used for phenol degradation (prince et al., 2015). from the studies of ldh-based composites that have been carried out, it appears that not a few have prepared ldhtypemetaloxidesldh-tio2 andldh-znoasphotocatalysts for organic pollutant degradation. ldh composited with tio2 or zno has advantages. ldh is a dispersant for tio2 owing to the surface hydroxyl group, thereby simultaneously generating and enhancing photocatalytic properties (contreras-ruiz et al., 2019). meanwhile, zno is often considered an alternative to tio2 because it can absorb a wider spectrum of energy than tio2 (amor et al., 2018). this study is intended to prepare zn/al-tio2 and zn/al-zno from the basic structure of zn/al ldh which has been synthesized, the catalysts used in the degradation of congo red (cr) dye. the calcination temperature of the composite preparation was used at 300◦c, which was relatively low compared to the calcination temperature of several previous studies. 2. experimental section 2.1 materials and instrumental the starting chemicals used in this study were aluminum nitrate by merck, zinc nitrate by smart-lab, titanium dioxide by merck, zinc oxide by loba chemie, sodium carbonate by merck hydrogen chloride by mallinckrodt labguard, and sodium hydroxide by merck. congo red was measured by uvvis biobase bk-uv1800 pc. characterization of morphology materials was performed by sem quanta-650 oxford instrument, band gap energy provided by uv-drs jasco v-760, diractogram by rigaku xrd miniex-6000, and analysis of functional groups by ftir alpha bruker. 2.2 synthesis of ldh the synthesis of zn/al ldh was adjusted according to the modied procedure of yan et al. (2016) namely by coprecipitation. 50 ml of zinc nitrate and aluminum nitrate each with a mole ratio of zn/al= 3 to form a total concentration of 1 m stirred for 2 hours. to this solution, 0.5 m alkaline and 0.25 m na2co3 were added, each 60 ml for ph 10 conditioning. the mixture was stirred for 10 hours at 80◦c. the precipitate formed was ltered, washed and dried at a temperature of 110◦c, then the precipitate was weighed. 2.3 preparation of composite the zn/al-tio2 photocatalyst was prepared according to the zn/al ldh synthesis procedure. a mixture of zinc nitrate and aluminum nitrate was added with alkaline and na2co3, after being stirred for 10 hours, it was impregnated with tio2 using a weight ratio of ldh/tio2= 1. the best ratio of zn/al to tio2 is 1 (djeda et al., 2020). the mixture was stirred for 3 hours and added 150 ml of 0.37 m base, then stirred again for 10 hours at a temperature of 70◦c. the mixture produced a precipitate and was ltered, washed, and then calcined at a temperature of 300◦c for 7 hours. the zn/al-zno photocatalyst was prepared according to the same process but the oxide used was zinc oxide. 2.4 photodegradation by catalysts prior to the photodegradation process, the catalyst was contacted with a dye model in the form of a solution of 100 mg/l cr as much as 20 ml and shaken in the dark for 60 minutes. variations in photodegradation conditions under uv 352 nm included variations in ph, catalyst weight, and time. the rate constant (k) was determined according to the equation of the integral result of the langmuir hinshelwood formulation, the equation ln (c0/c) = k.t produced the value of k as the slope. c0 was the residual concentration of cr after contact in the dark room. ct was the remainder of the cr constraint after being degraded during a certain time (t). cr was analyzed by uv-vis at 497.8 nm. the ultrasonic desorption process and material stability were studied from a 5-cycle regeneration study. 3. result and discusssion 3.1 eect of photodegradation conditions one of the things that have an eect on the photodegradation of dye is the ph condition of the media. figure 1(a) shows the variation of ph to cr photodegradation. at ph 4, it appears that zn/al ldh produces the lowest c/c0 or the highest cr photodegradation. cr is an anion so it can be more compatible with the positive charge of the photocatalyst under acidic conditions. figure 1(a) also shows zn/al-tio2 has an optimum ph at ph 3 while zn/al-zno is optimum at ph 6. this study found that the optimum ph when using zn/al-zno was higher than using zn/al-tio2, this was found to occur because according to elhalil et al. (2018) under acidic conditions zno is at risk of being decomposed by electron holes h+ and also dissolution into zn2+. variations in the weight of the catalyst used can aect the photodegradation process. the more catalysts used within certain limits will provide optimum conditions. figure 1(b) shows the eect of catalyst weight on cr photodegradation. it can be seen in the gure that the heavier the catalyst used, the better the photodegradation tendency. the decrease in the photodegradation performance of the zn/al-zno catalyst at 0.1 g according to elhalil et al. (2018) and yuliasari et al. (2022b) could be due to light being more dicult to penetrate into the media. © 2022 the authors. page 450 of 454 yuliasari et. al. science and technology indonesia, 7 (2022) 449-454 figure 1. eect of media ph (a) catalyst weight (b) on cr photodegradation the varied time can show the optimum condition of photodegradation. figure 2(a) shows the photodegradation of cr for each catalyst over time. the photodegradation results showed that after zn/al ldh was modied to ldh-metal oxide, it could improve the photodegradation performance. zn/al catalyzed degradation of cr for 120 minutes as much as 68.39%, zn/al-tio2 as much as 81.24%, and zn/al-zno as much as 71.09%. photodegradation progresses better with an increasing rate constant. figure 2(b) shows the rate constant for cr degradation in the presence of catalysts. the rate constant was increased when using a composite catalyst compared to the pristine structure ldh. the rate constants (k) using zn/altio2 and zn/al-zno composites were 0.0158 and 0.0120, respectively, while using zn/al ldh was 0.0083. several rate constants obtained by photodegradation studies of organic pollutants include catalyst zn/al-tio2 with k 0.0060 (contrerasruiz et al., 2019); catalyst zn/alce with k 0.0043 (suárezquezada et al., 2016) and catalyst znmn/al with k 0.0013 (morales-mendoza et al., 2015). figure 2. eect of time (a) rate constants of catalysts (b) on cr photodegradation ldh materials can be modied with metal oxides to form composites that have better structural strength (djeda et al., 2020; yuliasari et al., 2022a). figure 3 shows that ldh-metal oxides, namely zn/al-tio2 and zn/al-zno are better in the reuse of the material up to 5 regeneration photodegradation cycles than zn/al ldh as the pristine structure. figure 3. catalyst regeneration cycle 3.2 characterization of fresh and reuse materials catalyst performance can be explained by surface conditions or surface morphology. the morphological conditions of the fresh catalysts can be seen from the 500 times magnication of sem images in figure 4 shows the surface of catalysts. sem images of zn/al-tio2 appear to be more homogeneous than zn/al-zno. figure 4. sem images of fresh catalysts: zn/al ldh (a) zn/al-tio2 (b) zn/al-zno (c) ldh-based materials are classied as semiconductors if they are known to have band gap energy values below 6. characterization of the band-gap energy of catalysts using uv-drs instruments. as shown in figure 5, the catalysts have band gap energies, namely zn/al-tio2 3.20, zn/al-zno 3.18, and zn/al ldh slightly dierent at 3.17. the catalystst material after 5 cycles of degraded cr was analyzed byxrd. figure 6(a) shows the xrd diractogram of the catalysts. it can be seen in the gure that zn/al ldh which has been used in 5 degradation cycles still has a 2\ around 10◦ which is typical for the structure of the ldh cationic layer, and a 2\ around 60◦ from the anionic interlayer (siregar et al., 2022). this study also is in line with contreras-ruiz et al., © 2022 the authors. page 451 of 454 yuliasari et. al. science and technology indonesia, 7 (2022) 449-454 figure 5. band gap energy of fresh catalysts 2019 that the tio2 peak of ldh-tio2 appears at 2\ around 25◦, 54◦, 55◦, and 69◦. while zn/al-zno still shows the typical peak of ldh at an angle of 32◦, 34◦, 36◦, 48◦, 56◦, 63◦, and 68◦ which is in line with bhuvaneswari et al. (2019). analysis of the functional groups contained in the catalyst materials that have degraded the dye was carried out by ftir. figure 6(b) shows the ftir spectra of catalyst materials that were used in the degradation of cr. zhao et al. (2018) stated that the band around 3400 cm−1 is the stretching oh vibration of ldh and conveyed that the band around 1360 cm−1 is a vibration of co32−. the band between 400 cm−1 to 800 cm−1 that appears according to aoudjit et al. (2019) is a vibration of the bond between metal elements and oxygen. the 1620 cm−1 band is probably the vibration of the azo group or the primary amine group (nandiyanto et al., 2019), where cr has these functional groups. figure 6. xrd diractogram of reuse catalysts (a) ftir spectra of reuse catalyst (b) after cr photodegradation for 5 cycles of regeneration 4. conclusion modication of zn/al ldh into ldh-metal oxides, namely zn/al-tio2 and zn/al-zno increases the photodegradation performance. the percentage degradation and rate constant of congo red (cr) usingzn/al ldh increased when usingzn/almetal oxides. the regeneration cycle showed that zn/al-tio2 and zn/al-zno had better stability than zn/al-ldh. after the materials degraded cr in the fth regeneration cycle, the xrd diractogram still shows that the catalyst has a cationic layer structure for zn/al ldh catalyst and tio2 or zno. similarly, the ftir spectra after the materials were used up to the fth regeneration cycle still show the presence of hydroxy groups, interlayer anions, and metal oxides. this characterization data can show that the stability of the catalyst material is well. 5. acknowledgment the authors deeply acknowledge to research centre of inorganic materials and coordination complexes fmipa universitas sriwijaya for instrumental analysis. references abderrazek, k., f. s. najoua, and e. srasra (2016). synthesis and characterization of zn-al ldh: study of the eect of calcination on the photocatalytic activity. applied clay science, 119; 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7002–7014 zhu, j., z. zhu, h. zhang, h. lu, y. qiu, l. zhu, and s. küppers (2016). enhanced photocatalytic activity of ce-doped zn-al multi-metal oxide composites derived from layered double hydroxide precursors. journal of colloid and interface science, 481; 144–157 © 2022 the authors. page 454 of 454 introduction experimental section materials and instrumental synthesis of ldh preparation of composite photodegradation by catalysts result and discusssion effect of photodegradation conditions characterization of fresh and reuse materials conclusion acknowledgment research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 3 (2018) 41-44 © 2018 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 3 november 2017; revised 20 january 2017; accepted 20 january 2018 http://doi.org/10.26554/sti.2018.3.1.41-44 morphological diversity of lansiumdomesticum corr in south sumatra rupiah1, laila hanum2, zaidan p negara3, zulkifli dahlan2, indra yustian2 1 department of environmental biology graduate of sriwijaya university 2 department of biology, fmipa sriwijaya university 3 department of agriculture faculty of agriculture sriwijaya university email: rupiah.adel@student.pps.unsri.ac.id abstract researchon the morphological diversity of lansium domesticum corr in south sumatra. the research was conducted in april 2017 to june 2017. this research was conducted by means of exploration carried out in seven districts covering, east ogan komering ulu district, south ogan komering ulu district, ogan komering ulu district, musi rawas district, ogan komering ilir district, muara enim district and musi banyuasin district. sampling is done by using purposive sampling method. observation of morphological diversity was done by characterization of morphology and analyzed by descriptive method. the result of this research shows that in south sumatera, there were two variants of l. domesticum namely l. domesticum variant duku and l. domesticum variant langsat. keywords: lansium domesticum, morphology diversity, south sumatera 1. introduction lansium domesticum corr is a wet tropical plant in the form of trees. l. domesticum isalso one of the plants of the meliaceae family originating from western southeast asia from the thai peninsula in the west to kalimantan in the east. this species is still found growing wild in that region and still as one of the main cultivated fruits. from its country of origin, l. domesticum spread to vietnam, myanmar, and india (mayanti, 2009). lansium domesticum corr spread evenly in south sumatra province. statistical data from the department of agriculture and holticulture of south sumatera (2015) shows that the distribution of lansium domesticum spread in fifteen districts such asogan komering ulu (oku), ogan komeringilir (oki), muara enim, lahat, musi rawas, musi banyuasin, banyuasin, south ogan komeringulu, east ogan komering ulu, oganilir (oi), empat lawang, palembang, prabumulih, pagaralam and lubuk linggau, so that the lansium domesticum became one of the leading commodities and mascot flora in south sumatra. in term of the taxonomic status,duku, kokosan, and langsat still do not have a qualified classification. according to some taxonomists, the unqualified classification caused by the heightof the morphological resemblance, especially in duku and langsat (te-chato et al., 1995); the presence of partenocarps and apomixis occurring in duku, kokosan, and langsat, and morphological comparisons are difficult to distinguish since these plants often grow in the same location, besides that, the giving of regional names were inconsistent so that the same name were given for different varieties or otherwise,the different names used for the same varieties (verheij and coronel, 1997) morphological characters such as variations of leaf shape, fruit color, and fruit shape can be used as a basis in determining the categories of varieties. lim (2012) based on macromorphology placed duku, kokosan, and langsat into two varieties in one type of l. domesticum, l. domesticum var. typica known as dukuand l. domesticum var. pubescent koorders et valeton known as langsat and kokosan. in south sumatra lansiumdomesticumcorr has a different naming because of the character variation in the morphology of trees, leaves, and fruits.based on this, this study aimed to examine the morphological diversity of l. domesticumcorr in south sumatra. 2. experimental section 2.1. place and time this research was conducted in the duku production center area in south sumatera province. the sample identification was done at the graduate laboratory of sriwijaya university of palembang. the study was conducted from april 2017 to june 2017. 2.2. materials and instrumentation some tools and instrument used in this study were stationery, camera, scissors, calipers, meter and magnifier. the materials used in this work were bamboo samples and alcohol 70%, newsprints, rupiah et al. 2018 / science & technology indonesia 3 (1) 2018: 41-44 42 transparent plastic bag, tissue, adhesive plaster, paperboard, label paper, and research object (l. domesticum). 2.3. procedure sampling was done by means of exploration using purposive sampling method,and then performed the inventory of plants. specimens were obtained in the field were taken especially from the main organs of the plants such as branches, twigs, leaves and fruit for further identification. 2.3.1. morphological observation macromorphological observation was done by descriptive method. observations and measurements of the macromorphological data were performed on plant’s organs ie stem, leaves, flowers, and fruit in the form of qualitative and quantitative data. 2.3.2. identification further identification was done using taxonomy books e.g.prosea, plant resources of south east asia 2 (verheij and coronel, 1997); edible-medicine and non-medicinal plants, third edition: fruit (lim, 2012); flora of java, volume ii (backer and bakhuizen van den brink, 1965); morphology tumbuhan(rosantidewi, 2013) and journals on lansiumdomesticum. each sample was documented in the form of photographs. 2.3.3. making herbarium making herbarium was following onrizal method (2005) that includes i. sample collection, ii. processing and preservation and iii. mounting.the herbarium is taped to a rigid image paper and then attaches a completed identification label. 3. results and discussion research on l. domesticum morphological diversity in south sumatra was conducted in seven districts including kabupaen oki, east oku, oku, southern oku, muaraenim, muba, and musirawas. observation of morphological diversity was done by morphological characterizations by descriptive method. the results of morphological characterizations of l. domesticum were presented in table 1. the results in table 1 shows that of the five samples observed have different morphological characters both on fruit, stem and leaf characters. duku fruit is yellow, spherical, the skin of duku is thicker than the peel of langsat, the skin thickness is between 0.08 and 0.2, the presence of sap on ripe fruit slightly gummy, the flesh of fruit is white and somewhat transparent, duku fruit has a sweet taste, but there are some duku fruit that has a sweet acidity. langsat fruit is yellow, oval or rounded elongated, thin fruit skin thickness ranges from 0.03-0.06, smaller fruit with fruit diameter ranging from 3 to 4 cm, the presence of sap on ripe fruit many, fruit flesh is white and cloudy, and the taste of fruit is acid. in addition to having differences in fruit morphological characteristics there are differences in leaf morphological characters. leaves of duku and langsak are elliptical, the top and bottom surfaces of the leaves are hairless, the tip of the leaf is tapered, green color, some are yellowish green.while the leaves langsak bulu, langsak nipis and langsat, the surface of the bag and the bottom of the leaves are smooth-haired, dark green with pinnate leaf bone, flat edges, elliptical leaf shape. duku and langsak have trunkheight varying between 6 15 m, trunk winding from 34 300 cm trunk height and winding in table 1.morphological characterizationsof lansium domesticum in south sumatra organ characterizations duku langsak langsakbulu langsaknipis langsat trunk trunk height (m) 6 – 15 6 – 15 6 – 7 7 – 8 8 – 10 branch type monopodial monopodial monopodial monopodial monopodial trunk color brown brown grayish brown grayish brown grayish brown trunk winding (cm) 34 – 300 46 – 300 35 – 87 86 98 canopy condition covered with dense leaves covered with dense leaves opened with rarely leaves opened with rarely leaves opened with rarely leaves leaf the presence of hair on the top and bottom surfaces of the leaves hairless hairless smoothed hair on the top and bottom surfaces of the leaves smoothed hair on the top and bottom surfaces of the leaves smoothed on the top and bottom surfaces of the leaves leaf tip tapered tapered tapered tapered tapered leaf length (cm) 9,3 – 30 13,2 – 28,4 9,5 – 24 10 – 17 10 – 17 leaf width (cm) 5,8 – 18,5 7,4 – 16 7,5 – 11,3 5,5 – 9,3 5,5 – 7,1 leaf color yellowish green green dark green dark green dark green leaf bone pinnate pinnate pinnate pinnate pinnate leaf edge flat flat flat flat flat leaf shape ellipse ellipse ellipse ellipse ellipse fruit rind thickness (mm) 0,08 0,2 0, 08 – 0,1 0,03 – 0,06 the number of seeds per fruit 3-feb 2 – 3 3 – 4 number of fruits 10 – 30 12-aug 20 – 30 fruit shape spherical spherical oval fruit color yellow yellow yellow fruit diameter (cm) 8 – 12 9-aug 8 – 9 rupiah et al. 2018 / science & technology indonesia 3 (1) 2018: 41-44 43 accordance with the age of the plant. the type of branch ismonopodial,and closed canopy condition with dense leaves. langsat, langsakbulu, danlangsaknipishave a height of 6 10 m, girth 45 98 cm, grayish brown of trunk color, monopodial branching type, and opened canopy condition with rare leaves. verheij and coronel (1992) stated that lansiumdomesticumcorr is a fruit tree with a height of 15 to 20 m and a trunk diameter of 35-40 cm. in the trunkthere are deep grooved and stretched high, bark duku colored brown greenish or grayish, cracked and has a white gummy. lansiumdomesticum has a monopodialtrunk branching type, the main stem is clearly visible, easy to distinguish with its branches either the direction or the size, trunk color is brown or grayish brown. morphological characterizations of duku, langsak, langsat, langsakbulu and langsaknipis refer to ridley (1931); morton (1987); and lim (2012) in hanum (2013). morphological characters such as variations in leaf shape, fruit color, and fruit shape can be used as a basis in determining categories of varieties (lawrence, 1951). determination of taxonomic status of duku, kokosan, and langsat on ridley variety category (1931); morton (1987); and lim (2012) in hanum (2013) using the character of hair presence on the top and bottom surfaces of the leaves. ridley (1931) in lim (2012) places duku, kokosan, and langsat as two varieties, l. domesticum var. typica (duku) and l. domesticum var. pubescent (kokosan and langsat) based on the presence of hair on the top and bottom surfaces of the leaves, the presence of hair on the petals, the shape of fruit, the thickness of the fruit skin, the presence of sap on the ripe fruit, the nature of seeds, fruit taste, and seed size. based on macromorphological characterization results,duku and langsak have similar morphological characters to l. domesticum (a) (b) (c) (d) (e) . (f) (g) (h) (i) (j) (f) (g) (k) (l) (m) (n) (o) (p) figure 1.differences in morphological characters, (a) leaf morphology of langsaknipis(b) leaf morphology of langsakbulu(c) leaf morphology of langsat, (d) leaf morphology of langsak, (e) leaf morphology of duku, (f) canopy condition of langsaknipis, (g) canopy condition of langsakbulu, (h) canopy condition of langsat, (i) canopy condition of langsak, (j) canopy condition of duku, (k) fruit morphology of langsat, (l) fruit morphology of langsak, (m) fruit morphology of duku, (n) the flesh of fruit morphology and skin thickness of langsat, (o) the flesh of fruit morphology and skin thickness of langsak, (p) the flesh of fruit morphology and skin thickness of duku. rupiah et al. 2018 / science & technology indonesia 3 (1) 2018: 41-44 44 var. domesticum (duku) and macromorphological characterization langsat, langsakbulu and langsaknipis has similar morphological characters to l.domesticum var. pubescent. according to davis and heywood (1973); stace (1979) varieties (local races), a population consisting of one or several biotypes, have distinctly different morphological characters, scattered in a limited (local) region within a species distribution, so the variety is called a local race. according to brandenburg (1986), group categories can be synonymous with varieties in a formal taxonomy whereas radford (1986) states that group formation is based on the closeness of the relationship between a taxa to another taxa which is determined by so many similar properties between the taxon. morphological characters that support the placement in the varieties category,especially from the presence of hairs on top and bottom surfaces of leaves, fruit shape, presence of sap on ripe fruit, fruit taste, fruit skin thickness, crown condition (figure 1). duku (l. domesticumvarduku) generally has a large tree, a bright green leaf with an upper and lower leafless surface with a relatively short bunch and contains a small amount of fruit, a pruning grain of 3-10 grains per cluster. the fruit is large, spherical and thick skin, non-gummy rind of fruit when ripe, thick fleshy, has small seeds, sweet or sticky, and smells nice.while langsat (l. domesticumvar, domesticum) , dark green leaf with top and bottom surfaces are soft and less dense, with upright branching. the fruit bunches are long, solid containing 15-25 grains per cluster that are oval. the fruit has a thin skin, the flesh tastes sour refreshing. in general, langsat cannot last long and more easily blackened after picking from the tree (verheij and coronel, 1997; lim, 2012 in hanum and kasiamdari, 2013). according to singh (1999),the variations of morphology shown by organism were the result of interaction between the genetic factors and the environment in which the organism was alive. davis and heywood (1973) suggest that morphological variations, genetically arising from mutation, recombination, and gene flow events, while ecologically emerging through a series of physiological processes due to the differences in illumination, temperature, water, wind, soil, and organisms.verheij and coronel (1997) states,l. domesticum is a complex and varied species with wild varieties and cultivation. this is partly due to the occurrence of partenocarpy events, apomixis, and natural crosses so that taxonomic status duku, kokosan, and langsat become increasingly complex. backer and van de brink (1965) and morton (1987) reported l. domesticum var. pubescent (langsat) as wild type. kosterman (1960) states langsat is a hybrid between duku and kokosan. 4. conclusion based on the morphological assessment of l. domesticum in south sumatra, there are two variants of l. domesticum were l. domesticum variant duku and l. domesticum variant langsat. morphological characters that distinguish between duku and langsat variants are found under canopy conditions, presence of hair on top and bottom surfaces of leaves, fruit shape, fruit skin thickness, fruit taste, and the presence of sap on ripe fruit. acknowledgement the researcher would like to thank prof. dr. h. zulkiflidahlan, m.si, dea who has funded this research through a grant project with contract number no. 987 / un9.3.1 / pp / 2017. date july 21, 2017. the author also thanks all those who have assisted in doing this research. references backer, c.a. and brink, den, van, jr. r.c.b. 1965.flora of java (spermatophytes only). vol. ii. n.v.p. noordhoff. groningen. netherland. brandenburg wa. 1986. classification of cultivated plants. actahorticulturae. 182: 109-115. davis ph and heywood vh. 1973. principles of angiosperm taxonomy. robert e.krieger publishing company, inc.huntington. new york. dinas pertaniantanamanpangandanhortikultura, 2015.statistiktanamanpangandanhortikultura 2015. sumatera selatan. hanum, l., kasiamdari,r.s., santosa, dan rugayah., 2013. karaktermakromorfologi dan mikromorfologiduku, kokosan, langsatdalampenentuan status taksonomipadakategoriinfraspesies. biospecies.vol. 6 no.2. kartina, am..2003. karakteristiklahandantanamanterhadaphasilbuahduku di sumatera selatan.jurnalwacanapertanian, vol.2 no.1. lim, t.k., 2012. edible medicinal plant.3th vol. fruits.springer. new york. mayanti, t., 2009.kandungan kimia danbioaktivitastanamanduku.unpad isbn 978-979-3985-37-4. morton j., 1987. langsat.p201-204. dalamjulia fm (ed.) fruit of warm climates. miami florida. onrizal. 2005. teknik pembuatan herbarium. e-usu repository. universitas sumatera utara. radford ae, 1986. fundamentals of plants systematics.harper and rowpublishers.inc. new york. rosanti, d. 2013. morfologitumbuhan. erlangga. jakarta stace ca. 1979. plant taxonomy and biosystematics. edward arnold. london. p. 5-6, 86-98. susilawati,munandar, merida, j.d., 2016. kajianragamaksesiduku (lansiumdomesticumcorr.) di kabupatenmusibanyuasinberdasarkankaraktermorfologi, anatomidanfisiologi.jurnallahan suboptimal.vol. 5, no.1. verheij e.w. m. dan coronel re.1997. sumberdayahayati asia tenggara 2.prosea. pt. gramediapustakautama, jakarta. verheij, e.w.m., and coronel, r.e., 1992. edible fruits and nuts. lansiumdomesticumcorrea.plant resources of south-east asia. no: 2. prosea bogor indonesia. science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2016) 8-15 article http://sciencetechindonesia.com @2016 published under the terms of the cc by nc sa 4.0 license 8 thermal stability of polyoxometalate compound of keggin k8[2-siw11o39]∙nh2o supported with sio2 yunita sari m a1,* and maria danesti situngkir1 1deoartment of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail: yuniaritonang15@yahoo.com abstract synthesis through sol-gel method and characterization of polyoxometalate compound of k8[2-siw11o39]∙nh2o supported with sio2 have been done. the functional groups of polyoxometalate compound was characterized by ft-ir spectrophotometer for the fungtional groups and the degree’s of crystalinity using xrd. the acidity of k8[2-siw11o39]∙nh2o/sio2 was determined qualitative analysis using ammonia and pyridine adsorption and the quantitative analysis using potentiometric titration method. the results of ft-ir spectrum of k8[2-siw11o39]∙nh2o appeared at wavenumber 987.55 cm-1 (w=o), 864.11 cm-1 (w-oe-w), 756.1 cm-1 (woc-w), 3425.58 cm-1 (o-h), respectively and spectrum of k8[2-siw11o39]sio2 appeared at wavenumber 956.69 cm-1 (w=o), 864.11 cm-1 (w-oe-w), 3448.72 cm-1 (o-h), respectively. the diffraction of xrd pattern of k8[2-siw11o39]∙nh2o and k8[2siw11o39]∙nh2o/sio2 compounds show high crystalinity. the acidic properties showed k8[2-siw11o39]∙nh2o/sio2 more acidic compared to k8[2-the siw11o39]∙nh2o. the qualitative analysis showed pyridine compound adsorbed more of polyoxometalate compound of k8[2-siw11o39]∙nh2o/sio2. analysis of stability showed that the k8[2-siw11o39]∙nh2o/sio2 at temperature 500°c has structural changes compare to 200-400oc which was indicated from vibration at wavenumber 800-1000 cm-1. keywords : k8[2-siw11o39]∙nh2o, polyoxometalate, sio2. introduction polyoxometalate compound is the cluster compound of metal-oxygen which acid-base properties, it has various structural and oxidation rates, so it is very effective for both acid-base reaction and reduction oxidation reaction catalyst (yamase dkk, 2002). polyoxometalic compounds are effective as catalysts because they have higher acidity than sulfuric acid and not toxic (okuhara et al, 1996). this compound has been applied as a catalyst in industrial processes in developed countries such as japan (nakagawa and mizuno, 2007). the research of polyoxometalate compounds are primarily intended in terms of its superiority as a catalyst which can be performed either in homogeneous or heterogeneous systems depending on the medium are used. in a heterogeneous system, the polyoxometalate compound can be used repeatedly in catalytic reaction. the polyoxometalate compound has a low surface area and high solubility in a polar solvent (kim et al, 2006). the catalyst which have a small surface area is suitable for homogeneous catalysts while the homogeneous catalysts can not be recycled. to designed the polyoxometalate compound as a heterogeneous catalyst, modification should carried out by embedding. modification of polyoxometalate compounds can be embedding by inclusion using both metal oxide and non-oxide metals (nerwman et al, 2006). the embedding is carried out to have a large surface area which can be used as heterogeneous catalysis and can increase the acidity of the compound, so that the article history submitted: 2 august 2016 accepted: 15 september 2016 doi: 10.26554/sti.2016.1.1.8-15 catalytic properties increase. the catalytic activity is affected by the temperature, surface area, and acidity of the catalyst. the temperature affects collisions between molecules and certain chemical reactions require heating at high temperatures to obtain maximum results. as an example the hydroxylation reaction of n-hexane requires the temperatures above 400 ° c and requires the bronsted acid side in the reaction to obtain a high percent conversion (eid et al, 2013). the synthesis of h4[γ-h2siv2w10o40] has been carried out with various variations of embedding sio2, tio2, zrocl2 and tacl5 by karim (2014), which the product material has not been tested for its qualitative and quantitative acidity. meanwhile marci (et al 2013) has carried out the research by embedding keggin h3pw12o40 type polyoxometalate compounds with various metal oxides such tio2, sio2, zro2, zno, and alo2. from the many several metal oxides which has been used, polyoxometalate compounds which are embedded with sio2 have higher catalytic character which applied to the propene hydration reaction. in this research, the synthesis of keggin k8[2siw11o39]∙nh2o polyoxometalate compound which is embedded by sio2 metal oxide. the metal oxide of sio2 was obtained from reaction of tetraethyl orthosilical hydrolysis (teos) known as the sol gel method. the embedded result of synthesized polyoxometalate compounds were characterized by a frourier transform infra red (ft-ir) spectrophotometer and xray difractometer (xrd). polyoxometalate compounds k8[2siw11o39]∙nh2o was soaked on the acid compounds before and after embeddded qualitatively and quantitatively. the thermal stability character of k8[2-siw11o39]∙nh2o and k8[2siw11o39]∙nh2o/sio2 were tested by heating it at various temperature using furnace and the heating results were sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 9 characterized by a ft-ir spectrophotometer. the acidity and thermal stability character of polyoxometalate compounds were tested perior to be used as catalysts in chemical reactions that require heating at high temperatures. experimental section the insturments which used in this research x-ray diffractometer (xrd) rigaku miniflex 600 and ft-ir shimadzu prestige-21 spectrophotometer. the substances used in this research were sodium metasilicate (na2o3si), sodium tungstate (na2wo4), hydrochloric acid (hcl), potassium chloride (kcl), potassium carbonate (k2co3), tetraethyl orthosilika (teos), sodium bis (2-ethylhexyl) sulfosuccinate, cyclohexane, pyridine, ammonia (nh3), n-butylamine, acetonitrile and aquades (h2o). synthesis of polyoxometalate compounds k8 [2siw11o39]∙nh2o and its characterization the 11 g (50 mmol) na2o3si compound was dissolved in aquades (100 ml) and 4m hcl depleted slowly to a ph range of 5-6 and stirred. the solvent was mixed with na2wo4 of 182 g (0.55 mmol) which was dissolved with aquades (100 ml). the mixture was added with kcl of 80 g. with the addition of the mixture to be white and formed of sediment. after that, the mixture was filtered using filter paper, then the solid was dried to obtain the compound k8[2-siw11o39]∙nh2o. the solid obtained was white solid. the polyoxometalate compound k8[2-siw11o39]∙nh2o was characterized by a ft-ir spectrophotometer and x-ray diffractometer (xrd). the`synthesis k8[2 siw11o39]∙nh2o/sio2 with sol-gel method and its characterization the synthesis of compound k8[2-siw11o39] ∙nh2o/sio2 was modified from the procedure of (kim et al 2006). sodium bis (2-ethylhexyl) sulfosuccinate of 1.5 g was dissolved with 1 ml of cyclohexane (solvent a). the compound k8[2siw11o39]∙nh2o ∙ nh2o of 0.76 g was dissolved with slightly aquades (solvent b). solvent b is added to solvent a while distirer. a total of 11.2 ml of tetraethyl orthosilicate (teos) was added dropwise. stirred with stirer and heated at 60 oc for 2 hours. the white solids formed are k8[2siw11o39]∙nh2o/sio2 and dried by vacuum. the compounds k8[2-siw11o39]∙nh2o/sio2 are characterized by a ft-ir spectrophotometer, and x-ray diffractometer (xrd). the acidity test of compound k8[2-siw11o39]∙nh2o and k8[γ-siw10o36]∙nh2o/sio2 is qualitatively a total of 0.5 g of each k8[2-siw11o39]∙nh2o and k8[2siw11o39] ∙nh2o/sio2 were inserted into vials. a total of 10 ml of pyridine and 25% ammonia (nh3) were each fed into a beaker glass. a vial bottle was inserted into a beaker glass containing pyridine and ammonia and then sealed tightly with a kreb plastic. the compound was allowed for two days to adsorption between pyridine and ammonia with polyoxometalic compounds. compounds that have been in contact with pyridine and ammonia were tested qualitatively by characterizing using a ftir spectrophotometer. the acidity test of compound k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 a total of 0.1 g of each of the k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 were dissolved in 8 ml acetonitrile and stirred for 3 hours with a magnetic stirrer. the suspension was titrated with n-butylamine 0.05 m which was monitored by glass electrode as a ph sensor. each droplet per volume of titrant was recorded to be the potential generated and connected between the volume of the titrant and the resulting potential. the classification of forces from the acidity side is classified on a scale of: e> 100 mv (very acidic); 0> e> 100 mv (acid side); -100 <e <0 mv (weak acid side); and e <-100 mv (acid side is very weak). the thermal stability test k8[2siw11o39]∙nh2o/sio2 the k8[γ-siw10o36]∙nh2o/sio2 was heated at 200 ° c, 300 ° c, 400 ° c and 500 ° c for 2 hours in the furnace. the heating compound was cooled and characterized by an ftir spectrophotometer. results and discussion synthesis and characterization of keggin type polyoxometalate compounds k8[2-siw11o39]∙nh2o the synthesis of compound k8[2-siw11o39]∙nh2o was performed by addition of potassium chloride (kcl) to the compound [2-siw11o39]∙nh2o acting as a k+ ion donator. at the end of the synthesis process there was obtained a white solid which was a compound k8[2-siw11o39]∙nh2o. the result of synthesis in the form of white solid was then characterized using ft-ir spectrophotometer which aims to identify the functional group formed as shown in figure 1. figure 1. ftir spectra of polyoxometalate compound k8[2siw11o39]∙nh2o the peaks of the functional groups of polyoxometalate compounds appearing at wave numbers 4000-300 cm-1 shows in figure 1. the principal uptake of k8[2-siw11o39]∙nh2o compounds shows the presence of vibration w = o appears in the 987.55 cm-1 region, the w-oe-w vibration of 864.11 cm-1 in which oxygen is located on the edge of the compound polyoxometalate and wave number 756.1 cm-1 for the vibration of the w-oc-w group which is the oxygen atom located at the center of the polyoxometalate compound. according to okuhara (et al 2001), the absorption of polyoxometalate compounds has w=o groups at wave number 980 cm-1, sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 10 vibration of w-oe-w group 878 cm-1, and vibration of w-ocw 779 cm-1. the compound k8[2-siw11o39]∙nh2o synthesis results in this study is in accordance with vibrations according to okuhara (et al 2001). in addition to the 3425.58 cm-1 wave numbers indicating the vibration -oh which indicates the presence of h2o in the polyoxometalate compound k8[2siw11o39]∙nh2o. the presence of a hydrogen bonding effect is characterized by a widened peak in the ft-ir spectrum of stuart (2004). k8[2-siw11o39]∙nh2o. after the compound k8[2-siw11o39]∙nh2o was characterized using ft-ir spectrophotometer, then the polyoxometalic compound k8[2-siw11o39]∙nh2o was analyzed by xrd. diffractogram of k8[2-siw11o39]∙nh2o polyoxometalate compound ∙ nh2o is presented in figure 2. figure 2. xrd diffraction patterns polyoxometalate compound k8[2-siw11o39]∙nh2o figure 2 shows the diffraction for the polyoxometalate compounds k8[2-siw11o39]∙nh2o with the highest intensity arising at 8°, 9°, 17°, 24° and 35° diffraction angles. according to yang (et al 2011) the diffraction for polyoxometalic compounds is present in some diffraction regions, ie 6-10°, 1520°, 22-25°, and 35-40°. the diffraction that appears below 10° in region 2θ shows that the polyoxometalate compound has a very high crystallinity. diffractogram of k8[2-siw11o39]∙nh2o compounds exhibiting sharp diffraction peaks indicates polyoxometalate k8[2-siw11o39]∙nh2o has very high crystalline properties in which the atoms of the polyoxometalate compound k8[2-siw11o39]∙nh2o is arranged regularly based on the length and angle of regular bonding. synthesis of keggin type polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 and characterization the polyoxometalate compound k8[2-siw11o39]∙nh2o which has been obtained was further prepared by proportion to sio2 obtained from teos hydrolysis. the embodiment was carried out by using a microemulsion and sol-gel method. eriksson (et al 2004) describes that microemulsions are liquids derived from a mixture of water, hydrocarbons, and surfactants. polyoxometalate compounds k8[2-siw11o39]∙nh2o/sio2 synthesis and characterization by functional group analysis using ft-ir spectrophotometer with ft-ir spectra presented in figure 3. the result of identification using ftir spectrophotometer to compound k8[2-siw11o39]∙nh2o/sio2 shows the specific vibration of polyoxometalic and sio2 compounds. figure 3 shows the difference shown by the ft-ir spectrum of the polyoxometalate compound k8[2-siw11o39]∙nh2o before being carried out with sio2. according to derrick (et al 1999) the symmetric vibration of si-o-si is at the wave number 1130-1000 cm-1. smith (1999) reported that the vibration of sio-si symmetric stretching was stronger at 1085 cm-1. the ftir spectra of compound k8[2-siw11o39]∙nh2o/sio2 undergo a shift of wave numbers for asymmetric si-o-si stretch vibration at 1103.28 cm-1. the shift of wave numbers occurs in vibration w=o. the w=o vibe before it is presented appears at the wave number 987.55 cm-1 and the vibration after carrying with sio2 appears at the wave number 956,69 cm-1. according to stuart (2004) vibration -oh vibration in the presence of hydrogen bonding effect is in the range of 3500-2500 cm-1 wavelength characterized by a widened peak on the ft-ir spectra. figure 3 (b) experiences a shift in the number of waves at the peak of 3448.72 cm-1 identifies the -oh vibration by the presence of h2o on the k8[2-siw11o39]∙nh2o/sio2 and the wave number at peak 3425.58 cm-1 identifies vibration -oh by the presence of h2o in the compound k8[2-siw11o39]∙nh2o/sio2. the primary wave numbers of k8[2-siw11o39]∙nh2o and k8[2siw11o39]∙nh2o/sio2 are presented in table 1. figure 3. ftir spectra of polyoxometalic compound k8[2siw11o39]∙nh2o (a), ft-ir spectra of polyoxometalate compound k8 k8[2siw11o39]∙nh2o/sio2 (b) table 1. wave number k8[2-siw11o39]∙nh2o and k8[2siw11o39]∙nh2o/sio2 vibration k8[2siw11o39]∙nh2o (cm-1) vibration k8[2 siw11o39]∙nh2o /sio2 (cm-1) type of vibration 987.55 956.69 w=o 864.11 864.11 w-oe-w 756.1 3425.58 3448.72 1103.28 w-oc-w o-h si-o-si the polyoxometalate compound ∙ k8[2-siw11o39]∙nh2o which was supported with sio2 then characterized using xrd. the diffraction angle and crystallinity of polyoxometalate compounds k8[2-siw11o39]∙nh2o/sio2. comparison of xrd of compound k8[2-siw11o39]∙nh2o with k8[2sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 11 siw11o39]∙nh2o/sio2 are presented in figure 4. (a) k8[2siw11o39]∙nh2o diffraction emerging below 10° in region 2θ indicates that the polyoxometalate compound k8[2siw11o39]∙nh2o has very high crystalline properties due to the atom of the polyoxometalate compound k8[2siw11o39]∙nh2o is arranged regularly based on the length and angle of bond formed. figure 4 (b) shows the xrd pattern of k8[2-siw11o39]∙nh2o/sio2. the compound k8[2siw11o39]∙nh2o/sio2 has a high crystallinity with a diffraction angle of 2θ each at 8°, 18°, 27°, and 34° indicating the characteristics of the polyoxometalate compound k8[2siw11o39]∙nh2o/sio2 in which the atoms of the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 were arranged regularly on the basis and length of the regular bonding. figure 4 (b) shows the pattern of xrd k8[2siw11o39]∙nh2o/sio2 indicating a change in the diffraction angle. figure 4. the diffraction pattern of k8 k8[2-siw11o39]∙nh2o (a), diffraction pattern of k8[2-siw11o39]∙nh2o/sio2 (b) the acidity test of compound k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 in qualitatively the acidity test of k8[2siw11o39]∙nh2o the acidity measurement of the polyoxometalate compound ∙ k8[2-siw11o39]∙nh2o is carried out both qualitatively and quantitatively. the ft-ir spectrophotometer method was performed for qualitatively, where k8[2siw11o39]∙nh2o polyoxometalate compound was saturated with ammonia and with pyridine for 2 days resulting in adsorption on the surface of k8[2-siw11o39]∙nh2o.. the saturation result were compared before or after being saturated with ammonia or pyridine. the saturation result was measured by a ftir spectrophotometer . the ftir spectra k8[2siw11o39]∙nh2o saturation result shown in figure 5. polyoxometalate compound k8[2-siw11o39]∙nh2o of the ft-ir spectra of figure 5 shows no absorption bands at 14001440 cm-1 wavelengths on a k8[2-siw11o39]∙nh2o saturated polyoxometalate compound with or without saturation pyridine. according to dines (et al, 1991) ammonia forms ammonium ions (nh4+) with the observed wave numbers at 1400-1440 cm1, but in the polyoxometalate compound∙ k8[2siw11o39]∙nh2o not exhibit ammonium ion vibrations (nh4+) at wave number 1400-1440 cm-1. ammonia can be adsorbed on the acid side of the heteropoly compound and in the metal cation (seo et al, 1988). ammonia was not adsorbed on the polyoxometalate compound k8[2-siw11o39]∙nh2o. it was possible that the polyoxometalate compound k8[2siw11o39]∙nh2o does not exhibit ammonium ion vibration (nh4+) at wave numbers 1400-1440 cm-1. figure 5 (b) shows a vibration of -oh at a wave number of 3448.72 cm-1 which identifies the presence of h2o in a polyoxometalate compound k8[2-siw11o39]∙nh2o. according to stuart (2004), vibration oh vibration, with the effect of hydrogen bonds in the range of 3500-2500 cm-1 wavelengths characterized by wider peaks in the ft-ir spectra. figure 5. ftir spectrum of polyoxometalate compound k8[2siw11o39]∙nh2o (a), ftir spectra of polyoxometalate compound k8[2-siw11o39]∙nh2o. saturation with ammonia (b), ft-ir spectra of polyoxometalate compound k8[2siw11o39]∙nh2o saturation with pyridine (c) polyoxometalate compound k8[2-siw11o39]∙nh2o compounds with saturation with pyridine in figure 5 (c) exhibit an –oh shift vibration appearing at a 3425.58 cm-1 wave number identifying h2o in a polyoxometalate compound k8[2siw11o39]∙nh2o. according to khalifah and prasetyo (2008) pyridine molecules bound to lewis acid sites absorbed at wave numbers 1400-1700 cm-1. figure 5 (c) ft-ir spectra does not show the wave number. in this case, pyridine was unsorbed in the polyoxometalate compound k8[2-siw11o39]∙nh2o. ft-ir digital specimen data of k8[2-siw11o39]∙nh2o compounds with saturation with ammonia and pyridine. the acidity test of k8[2-siw11o39]∙nh2o/sio2 the compound k8[2-siw11o39]∙nh2o/sio2 was saturated using ammonia and pyridine. then the material was characterized by an ft-ir spectrophotometer. the saturation result was measured by an ftir. the ft-ir spectra of k8[2siw11o39]∙nh2o/sio2 of the saturation results are shown in figure 6. figure 6 (a) shows the ftir spectra of a polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 before being saturated. figure 6 (b) shows the ftir spectra of a polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 with saturation using sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 12 ammonia. dennis (et al 1991) states that ammonia forms an ammonium ion (nh4+) with an observed wave number at 14001440 cm-1. seo (et al 1988) states that ammonia can be adsorbed on the acid side of the heteropoly compound and in the metal cation. the compound k8[2-siw11o39]∙nh2o/sio2 exhibits the vibration of the nh4+ ammonium ion appearing at the wave number 1404.18 cm-1. figure 6. ftir spectra of polyoxometalate compounds k8[2siw11o39]∙nh2o/sio2 (a), ft-ir spectra of polyoxometalate compounds k8[2-siw11o39]∙nh2o/sio2. saturation with ammonia (b), ft-ir spectra of polyhydroxide compound k8 [2k8[2-siw11o39]∙nh2o/sio2 saturation with pyridine (c) polyoxometalate compounds k8[2-siw11o39]∙nh2o/sio2 saturated with ammonia absorbance bands not found at wavelength 1400-1440 cm-1. in this case it is possible that the ammonia was not adsorbed on the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2. stuart (2004) states that vibration -oh vibration in the presence of hydrogen bonding effect is in the range of 3500-2500 cm-1 wavelengths characterized by a widened peak on the ftir spectra. polyoxometalate compounds k8[2-siw11o39]∙nh2o/sio2 exhibit a -oh loop vibration at 3425.58 cm-1 wave numbers identifying the presence of h2o in the polyoxometalate compound k8[2siw11o39]∙nh2o/sio2. figure 6 (c) shows the spectra of k8[2siw11o39]∙nh2o/sio2 compounds with saturation using ammonia also exhibiting a -oh looping vibration at a 3425.58 cm-1 wave number that identifies the presence of h2o in the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2. the caliph and prasetyoko (2008) explain that pyridine molecules bound to lewis acid sites are absorbed at wave numbers 14001700 cm-1. picture no. 10 (c) shows that the pyridine molecule has been adsorbed by the polymoxometalate compound k8 [2 k8[2-siw11o39]∙nh2o/sio2 shown in the wave number 1481.33 cm-1. this shows that the polyoxometalic compound k8[2-siw11o39]∙nh2o/sio2 has lewis acid character. based on the ftir spectrum of figure 5 and 6, it can be seen that the wave number 1404.18 cm-1 is a vibration of the ammonium ion nh4+. the compound k8[2siw11o39]∙nh2o/sio2 saturated with ammonia (figure 6 b) does not show the uptake of ammonia molecules at the 1404.18 cm-1 wave number as well as the compound k8[2siw11o39]∙nh2o (figure 5 b). in this case the ammonia is not adsorbed on the compound k8[2-siw11o39]∙nh2o and the compound k8[2-siw11o39]∙nh2o/sio2. the ft-ir spectra at figure 5 (c) does not show the uptake of pyridine molecules at the 1404.18 cm-1 wave number while the ft-ir spectra of figure 6 (c) of k8[2-siw11o39]∙nh2o/sio2 see the wave number 1481,33 cm-1 but does not show sharp spectra. it can be concluded that qualitatively pyridine adsorbed more on the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2. the acidity test of compound k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 in quantitative the acidity measurements of the k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 compounds were quantitatively measured by titration of potentiometric potassium using nbutylamine as titrant and acetonitrile as solvent. acetonitrile is an aprotic solvent as a solvent on the compound k8[2siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 so that only the acidity of k8[2-siw11o39]∙nh2o and k8[2siw11o39]∙nh2o/sio2. according to pecchi (et al 1985) using benzene solvent, acetonitrile and iso-octane as solvents in potentiometric titration and selected acetonitrile as a polar solvent to avoid the adsorption of n-butylamine and acetonitrile as an inert solvent the measurement by potentiometric method can determine the total acidity and acidity strengths of a polyoxometalate compound. the initial potential value (ei) identifies acidity strength from the surface side and classifies the acidity strength based on the range that classifies in scale: : ei > 100 mv (acidity is very strong), 0 < ei < 100 mv (strong acidity), -100 < ei < 0 mv (weak acidity), ei < -100 mv (acidity is very weak) (romanelli et al, 2004). the first derivative curve and the second derivative are made to be able to see where the titration equivalent point is shown in figure. 11 the equivalent point was performed to see the condition in which the base of nbutylamine is added precisely reacts with the acidic k8[2siw11o39]∙nh2o nh2o which was titrated. in addition, an equivalence point is performed to determine the amount of base volume of n-butylamine required to neutralize k8[2siw11o39]∙nh2o/sio2 acid. figure 7 shows the results of measurement of the compound k8[2-siw11o39]∙nh2o has an initial potential value of 54.4 mv. based on the potential value range of 0 < ei < 100 the polyoxometalate compound k8[2-siw11o39]∙nh2o has a strong acid side. the titration equivalent point is at 0.2 ml of nbutylamine volume reinforced by the first derivative curve and the second derivative of potentiometric titration. the titration equivalent point can be observed with sharp potential changes (mulja and suharman, 1995). figure 8 and 9 show the first derivative curves and the second derivative curves of the polyoxometalate k8[2-siw11o39]∙nh2o. the measurement of the acidity level of the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 is also carried out through potentiometric titration. from the titration curve presented in figure 10, the titration equivalent point was obtained at the time of titration volume of 0.4 ml n-butyamin. based on the data of the equivalence point it is found that the sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 13 polyoxometalate k8[2-siw11o39]∙nh2o/sio2 compound requires more base volume of n-butylamine to neutralize the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2. this indicates that k8[2-siw11o39]∙nh2o/sio2 is more acidic than a polyoxometalate compound k8[2-siw11o39]∙nh2o. this is also supported by looking at the potential initial value comparison. the initial potential value of k8[2-siw11o39]∙nh2o/sio2 ions is 76.6 mv whereas the initial potential value of k8[2siw11o39]∙nh2o compounds is 54.4 mv. the compound k8[2siw11o39]∙nh2o/sio2 is included in the acidic acid classification strong based on the potential value range of acid strength. increased density of polyoxometalate compounds k8[2siw11o39]∙nh2o/sio2 because the compound k8[2siw11o39]∙nh2o interacts with the carrier sio2. figure 7. potentiometric titration curve of compound k8[2siw11o39]∙nh2o figure 8. the first titular titration curve of potentiometric titration of compound k8[2siw11o39]∙nh2o figure 9. the second titular titration curve of potentiometric titration of compound k8[2-siw11o39]∙nh2o figure 10. potentiometric potentiometric curve of compound k8[2-siw11o39]∙nh2o/sio2 figure 11. the first derivative titration curve, potentiometric titration of compound k8[2-siw11o39]∙nh2o/sio2 figure 12. the second derivative titration curve, potentiometric titration of compound k8[2-siw11o39]∙nh2o/sio2 potentiometric titration method is an analytical technique based on the potential measurement of a sensor or electrode. the electrodes used are glass-containing glassed electrode, the liquid having the potential difference properties between the membrane and the electrolyte in contact with the membrane is determined by the activity of the particular ion. the membrane electrode used is a glass electrode. these glass electrodes are said to be ion-selective because they are specific only to h+ ions. potential measurements of polyoxometalate compound k8[2siw11o39]∙nh2o/sio2 can be performed with potentiometric titration because the compound k8[2-siw11o39]∙nh2o/sio2 has h+ ions. potentiometric titration curve of k8[2siw11o39]∙nh2o/sio2 can be seen in figure 10. the thermal stability compound of k8[2siw11o39]∙nh2o/sio2 the compound k8[2-siw11o39]∙nh2o/sio2 of results the preparation was heated at various temperatures to see the thermal stability of k8[2-siw11o39]∙nh2o/sio2. the heating results at various temperatures were characterized by ftir sari et al. / science and technology indonesia 1(1) 2016:8-15 @2016 published under the terms of the cc by nc sa 4.0 license 14 spectrophotometers. figure 13 shows the ft-ir spectra of the wavelengths that appear on the k8[2-siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 unheated and heated at various temperatures from 200-500°c. figure 13 shows the difference shown by the ft-ir spectra of the k8[2-siw11o39]∙nh2o compound before being carried out with sio2 or after heating. based on the ftir spectrum the warming of vibrations emerging undergoes a shift in the number of waves. figure 13 (a) and (b) show the wave numbers 3425.58 cm-1 and 3448,72 cm-1 while in figure 13 (c), (d), (e) and (f) indicate wave numbers 3433,29 cm-1, 3441,01 cm-1, 3425,58 cm1, 3402,43 cm-1 are identified as -oh groups in the presence of h2o with a slight amount seen from percent transmittance. figure 13 (f) shows excellent thermal stability properties in the presence of small amount of h2o which was characterized by a shift in the wavelength number of the -oh group. the vibration of polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 in the 800-1000 cm-1 wave range at 500°c shows slight differences due to vibration w=o overlapping with vibrations w-oe-w and w-oc-w. this suggests that on increasing the heating temperature may cause changes in the structure of polyoxometalate compounds. table 2 shows the vibrations of the k8[2-siw11o39]∙nh2o , k8[2-siw11o39]∙nh2o/sio2 without heating and after heating at a temperature of 200°c 500°c. figure 13. ft-ir spectra of polyoxometalic compound k8[2siw11o39]∙nh2o (a), ft-ir spectra of polymoxyalate compound k8[2-siw11o39]∙nh2o/sio2 (b), ft-ir spectra of polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2 of heating at 200°c (c), 300°c (d), 400°c (e), 500°c ( f). table 2. wave number of compound k8[2-siw11o39]∙nh2o, k8[2-siw11o39]∙nh2o/sio2 without heating and heating at a temperature of 200°c-500°c k8[2siw11 o39]∙n h2o k8[2siw11o 39]∙nh2 o/sio2 k8[2siw11o39]∙nh2o/sio2 vibrati on 200° c 300° c 400° c 500° c 987.55 864.11 756.1 3425.5 8 956.69 864.11 3448.72 887. 2 794. 6 3433 .2 887. 2 740. 6 3441 .0 987. 5 864. 1 732. 9 3425 .5 979. 8 858. 3 748. 3 3402 .4 w w=o w woe-w wwoc-w si oh conclusion polyoxometalate compounds k8[2-siw11o39].nh2o and k8[2-siw11o39]∙nh2o/sio2 were synthesized. the main vibration of the ir spectra of k8[2-siw11o39]∙nh2o shows the presence of vibration w=o appears in the area of 987.55cm-1. w-oe-w appears in the area of 864.11cm-1, w-oc-w appears in the area of 756.1cm-1, o-h, oh appears in the area of of 3425.58 cm-1 and for the compound k8[2siw11o39]∙nh2o/sio2vibration w=o appears in the region 956.69cm-1, w-oe-w appears at 864.11cm-1 and -oh area appears at 3448.72 cm-1. the xrd diffraction pattern for k8[2-siw11o39]∙nh2o differs at the diffraction angles of 8°, 9°, 17°, 24°, 35° and for the compound k8[2siw11o39]∙nh2o/sio2 appears at the angle of diffraction of 2θ each of 8°, 18°, 27°, and 34°. polyoxometalate compound k8[2siw11o39]∙nh2o/sio2 with a potential value of 76,6 mv has a higher acidity value than the compound k8[2-siw11o39]∙nh2o having a potential value of 54.3 mvv. qualitative analysis by using ammonia and pyridine to compound k8[2siw11o39]∙nh2o and k8[2-siw11o39]∙nh2o/sio2 it was found that the pyridine compound adsorbed more on the polyoxometalate compound k8[2-siw11o39]∙nh2o/sio2. the thermal stability test of the compound k8[2siw11o39]∙nh2o/sio2 shows at a temperature of 500oc of k8[2-siw11o39]∙nh2o/sio2 compound slightly altered the structure of the polyoxometalic compound characterized by overlapping of vibrations in the range of 800-1000cm-1. acknowledgement the author would like to thank you to prof. aldes lesbani, ph.d and dr.rer.nat. risfidian mohadi who have a rol in helping and guiding the author in this study references derrick, m. r., stulik, dustan., landry., james m., 1999. infrared spectroscopy in conversation science. the getty conservation institue. los angeles. dines, t. j., colin h. r., and andrew m. w., 1991. infrared and raman study of the adsorption of nh3, pyridine, no and no2 on anatase. journal chemical society, 87, 643-651. eriksson, sra., ulf nylen., sergio rojas., magali boutonnet., 2004. preparation of catalysts from microemulsions and their applications in heterogeneous catalysis. applied catalysis, 265, 207-219. karim, nopi. 2014. 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of ammonia on heteropoly compounds. journal of catalysis, 114, 469-472. smith, b. 1999. infrared spectral interpretation : a sytematic approach . crc press, new york. stuart, b., 2004. infrared spectroscopy : fundamentals and applications. john wiley & sons. ltd. yamase, t.;pope, m. t. eds. 2002. polyoxometalate chemistry for nano-composite design; kluwer: dordrecht. the netherlands. yang, s., yongkui huang., and li yu., 2011. catalytic application of h4siw12o40/sio2 in synthesis of acetals and ketals. advanced materials research, 284-286, 2374-2379. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper green synthesis of nickel aluminum layered double hydroxide using chitosan as template for adsorption of phenol hasja paluta utami1, nur ahmad2, zaqiya artha zahara3, aldes lesbani2,4, risfidian mohadi1,4* 1magister programme graduate school of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia2graduate school of mathematics and natural sciences, faculty of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia3magister programme in environment management, sriwijaya university, palembang, south sumatera, 30139, indonesia4research center of inorganic materials and coordination complexes, faculty of mathematics and natural sciences, sriwijaya university, palembang, south sumatera, 30139, indonesia *corresponding author: risfidian.mohadi@unsri.ac.id abstractin present study, a modification of the nial ldh composite with chitosan was successful. characterization was carried out usingx-rays, the results obtained show that there is an angle of 2\ at 11.57°(003); 22.91°(006); 35.04°(012); 39.73°(015); and 61.9°(110).the ft-ir spectrum of the chitosan@nial ldh at wavenumber 3448, 1635, 1543, and 601 cm−1. the nial ldh and chitosan have asurface area of 3.288 m2/g and 8.558 m2/g, respectively. an increase in the surface area of the composite chitosan@nial ldh 9.493m2/g, all of adsorbents follow type iv isotherm based on the classification according to iupac. the optimum ph of the nial ldh atph 3. the optimum ph for chitosan and chitosan@nial ldh material is at the optimum ph of 5. the kinetic and isotherm model inthe adsorption process is pseudo-second-order and freundlich model, respectively. the maximum adsorption capacity of nial ldh,chitosan, and chitosan@nial ldh is 25.445, 23.753, and 33.223 mg/g, respectively. the increase in regeneration cycles causes adecrease in the percentage of adsorbed; sequentially, the percentage adsorbed during the fifth regeneration reaches 3.545, 1.966,4.309%, respectively. keywordslayered double hydroxide, chitosan, phenol, adsorption received: 15 august 2022, accepted: 24 october 2022 https://doi.org/10.26554/sti.2022.7.4.530-535 1. introduction along with the increasing population and technological developments, water pollution is one of the severe problems faced and has become a concern of manyparties. one of the harmful pollutants in the environment is phenol (alves et al., 2019). phenol waste can come from production processes in various industries such as metal smelting, plastics, polymers, pharmaceuticals, paints, wood processing, organic pesticides, pulp, and paper (dehmani et al., 2021b; wang et al., 2022; zhang et al., 2022). the presence of phenol in the environmenst, especially waters, can disrupt aquatic ecosystems and human health (da silva et al., 2022). united state environmental agency (usepa) has limit concentration of phenol in water is 1 `g/l (de farias et al., 2022). therefore, to overcome the problem of environmental pollution, a solution is needed, one of which is the adsorption method (khan et al., 2022). adsorption has several advantages compared to other methods, including the relatively straightforward process, relatively high eectiveness, and eciency (jain et al., 2022). the adsorbent dramatically determines the success of the adsorption process, which is characterized bya large adsorption capacity. researchers have used many adsorbents to overcome environmental pollution problems, such as humic acid, zeolite, clay, activated carbon, chitosan, and layered double hydroxide (lesbani et al., 2021). layered double hydroxide (ldh) is an anionic clay material and hydrotalcite with the ability to exchange ions between layers, which has the general formula [m2+1−xm3+x(oh)2]x+[(an−)x/n·yh2o]x−, where m is divalent and trivalent metal cations (bouteraa et al., 2020). layered double hydroxides have been widely developed into adsorbents because they have good adsorption and uniqueness (taher et al., 2021). the development of ldh composites was also carried out on a hydrochar basis. research by juleanti et al. (2022) compared the adsorption ability of mg/al, ca/al, and zn/al composites based on hydrochar on the absorption of direct https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.530-535&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.530-535 utami et. al. science and technology indonesia, 7 (2022) 530-535 green dyes. the ability of these hydrochar-based composites to have adsorption capacities of 94.34 mg/g on mg/alhydrochar, 128.20 mg/g on ca/al-hydrochar, and 89.29 mg/g on zn/al-hydrochar. in addition, layered double hydroxide can be composited with chitosan. chitosan is known to have theabilityasanadsorbent, so it canbeused toabsorbhazardous materials in some wastewater. according to barbusiński et al. (2018), chitosan is a natural biopolymer that is well-known and good for water treatment. chitosan has physical and chemical characteristics, chemical stability, high reactivity, high chelation properties, and high selectivity to pollutants (seedao et al., 2018). in present study, a modication of the nial ldh composite with chitosan will be carried out. the prepared composite materials were characterized using x-ray diraction (xrd), fourier transform infra-red (ftir), and brunauer emmet teller (bet). the resulting composite material will be applied as an adsorbent of organic compounds in the form of phenol. the adsorption parameters to be determined are kinetics, isotherms, and adsorbent regeneration. determination of the adsorption parameters will be studied through variations in contact time, concentration, and temperature, as well as the desorption process. 2. experimental section 2.1 chemicals and instrumentation all chemicals; nickel hexahydrate (ni(no3)2.6h2o), aluminum nitrate nonahydrate (al(no3)3.9h2o), sodium carbonate (na2co3) , chitosan, hydrogen chloride (hcl), distilled water (h2o), sodium hydroxide (naoh), phenol (c6h5oh), 4-aminoantipyrine (c11h13n3o), potassium hexacyanoferrate(iii) (k3[fe(cn)6]) , and acetate buersolution (ch3coo na) ph 10. all instrumentation; x-ray diraction (xrd), spectrophotometeruv-visible,brunaueremmetteller(bet), and fourier transform infra-red (ftir). 2.2 synthesis of nial-ldh a total of 100 ml of a solution containing 0.75 m ni(no3)2. 6h2o was mixed with 100 ml of a solution containing 0.25 m al(no3)3.9h2o and then stirred for 30 min. furthermore, the ph of the mixture was adjusted to reach ph 10 with the addition of 2 m naoh. the resulting mixture was then stirred at a temperature of 65◦c for 24 h. the samples were ltered and washed with distilled water and then dried in an oven at a temperature of 100◦c. 2.3 preparation chitosan@nial ldh a total of 30 ml of 0.75 m ni(no3)2.6h2o were mixed into 30 ml of 0.25 m al(no3)2.9h2o solution, then stirred and added 3 gram chitosan. the naoh solution with a concentration of 2 m was slowly added to the mixture until it reached a ph of 10. solids were formed after 3 days of stirring at a temperature of 80°c. then the solid was ltered and washed with distilled water. the composite material obtained was dried at a temperature of 100°c. 2.4 adsorption of phenol adsorption parameters were studied through ph, contact time, concentration, temperature, and regeneration process variations. 0.02 g of adsorbent was put into an erlenmeyer containing 20 ml of phenol. adsorption was carried out with variations in ph (2-11), contact time (0-180 min), initial concentration (10-30 mg/l), temperature (30-60°c), and regeneration 5 cycles times. after that, the phenol solution was complex. the phenol complex process was conducted to xie et al. (2020) by adding 1 ml of 5 mg/l phenol solution into a beaker. then 0.1 ml of 2% 4-aminoantipyrine reagent was added, 0.1 ml of hexacyanoferrate (iii) 8%, 1 ml of ph 10 buer solution and 3 ml of distilled water were added. then the mixture was homogenized and allowed to stand for 5-10 minutes. afterward, the phenol concentration was measured using a uv-visible spectrophotometer at 505.2 nm. 3. result and discusssion characterizationwascarriedoutusingx-rays toproduceanial ldh diractogram, as shown in figure 1. the results obtained show that there is an angle of 2\ at 11.57°(003); 22.91°(006); 35.04°(012); 39.73°(015); and 61.9°(110). the success of the nial ldh synthesis can be proven by the research of ahmad et al. (2022) according to jcpds no.15-0087. the diraction pattern of chitosan at an angle of 2\= 7.93° and 19.35°. the 19.35° has a higher intensity than the peak of 7.93°. according to billah et al. (2020), the angle is 2\ at= 10° and 20°, indicating that the chitosan material is classied as semi-crystalline by jcpds data no.039-1894. the results of the characterization of chitosan@nial ldh composites showed that the typical peaks of double-layer hydroxyl were shown at angles of 2\= 11.45° and 60.93°, while the typical peaks of chitosan were at angles of 2\= 22.5°. figure 1. x-ray diractogram of adsorbents figure 2 shows the ft-ir spectrum of the chitosan@nial © 2022 the authors. page 531 of 535 utami et. al. science and technology indonesia, 7 (2022) 530-535 table 1. brunauer emmet teller of adsorbents parameter nial ldh chitosan chitosan@nial ldh surface area (m2/g) 3.288 8.558 9.493 pore volume (cm3/g), bjh 0.006 0.018 0.031 pore size (nm), bjh 16.983 19.102 17.057 ldh composite material. wavenumber 3448 cm−1 vibrations occur in the -oh group from water molecules. the o-h bending vibration in the nial composite is at a wavenumber of 1635 cm−1. the aromatic c=c group derived from chitosan is shown at the wavenumber 1543 cm−1. the nitrate group is at a wavenumber of 1543 cm−1, and the vibration for metal oxide is at a wavenumber of 601 cm−1. according to cardinale et al. (2020), the nial ldh is in the wavenumber region of 3600 cm−1. the o-h bonds in each layer are at 1632 cm−1. the wavenumber of 1348 cm−1 has nitrate groups, and the wavenumbers of 749 and 652 cm−1 have metal groups. figure 2. fourier transfer infra-red spectrum of adsorbents the graph nitrogen adsorption-desorption isotherms of nial ldh, chitosan, and chitosan@nial ldh can be seen in figure 3. the graph shows that each material belongs to the type iv isotherm based on the classication according to iupac. adsorption can be said to be a type iv isotherm if the adsorbent used has pores in the range of 2-50 nm, and there is an increase in adsorber absorption when the pores are lled with nitrogen (asnaoui et al., 2022; cao et al., 2022). the nial ldh and chitosan have a surface area of 3.288 m2/g and 8.558 m2/g, respectively. an increase in the surface area of the composite chitosan@nial ldh 9.493 m2/g. thus, from the data in table 1, it can be conrmed that the ldh modication process with chitosan material was successfully carried out, characterized by an increase in surface area. figure 3. graph nitrogen adsorption-desorption isotherms of adsorbents the eect of ph plays an essential role in the adsorption process (qu et al., 2022). figure 4 shows the optimum ph of the nial ldh at ph 3, with the adsorbed concentration reaching 13.355 mg/l. the optimum ph for chitosan and chitosan@nial ldh material is at the optimum ph of 5, with the adsorbed chitosan concentration of 10.414 mg/l, while chitosan@nialldhof14.663mg/l.accordingtoal-ghouti et al. (2022), when the solution’s ph is smaller or in an acidic solution state, the graphite oxide is positively charged, while in an alkaline solution or an alkaline solution, the surface of adsorbent is negatively charged. therefore, the eciency of phenol adsorption decreases at alkaline ph conditions; this is due to the electrostatic repulsion between phenol and the negatively charged surface of graphite oxide. figure 4. eect of ph on adsorption of phenol © 2022 the authors. page 532 of 535 utami et. al. science and technology indonesia, 7 (2022) 530-535 table 2. pseudo-first order and pseudo-second order parameter adsorbents qeexp pfo pso (mg/g) qecalc (mg/g) k1 (min−1) r2 qecalc (mg/g) k2 (g/mg.min) r2 nial ldh 12.274 7.224 0.030 0.9719 12.804 0.010 0.9997 chitosan 9.774 7.511 0.029 0.9452 10.311 0.008 0.9967 chitosan@nial ldh 13.722 14.997 0.048 0.8676 14.556 0.007 0.9987 table 3. langmuir and freundlich parameter adsorbent t (◦c) langmuir freundlich qmax kl r2 n kf r2 nial ldh 30 25.445 0.438 0.845 1.395 1.456 0.9478 40 25.063 0.055 0.8827 1.466 1.801 0.9447 50 23.041 0.079 0.9392 1.653 2.469 0.9516 60 24.155 0.088 0.9451 1.685 2.820 0.9548 chitosan 30 23.753 0.026 0.6276 1.270 6.703 0.9292 40 22.472 0.031 0.5671 1.295 2.078 0.8803 50 20.704 0.041 0.6888 1.362 4.248 0.8859 60 17.668 0.064 0.8866 1.581 7.579 0.9074 chitosan@nial ldh 30 29.851 0.037 0.662 1.366 1.472 0.9343 40 32.468 0.040 0.8074 1.348 1.652 0.9645 50 33.223 0.044 0.8483 1.357 1.828 0.9687 60 26.596 0.076 0.9052 1.609 2.685 0.9654 pseudo-rst order and pseudo-second order were used to determine the adsorption rate using the results of the data on the eect of phenol adsorption time in figure 5. the kinetic model in the adsorption process can be determined by looking at the value of the coecient of determination (r2) which is close to 1, the smallest value of the kinetic rate (k), and the similarity between the experimental qe value and the calculated qe. based on table 2, all adsorbent materials follow the pseudo-second-order kinetic model. this can be proven by the data of the coecient of determination (r2) which is close to 1, and the value of the kinetic rate (k2) in the pseudosecond-order kinetic model is smaller than the value of the pseudo-rst-order kinetic rate (k1), so it can be concluded that the reaction proceeds faster in the model pseudo-second order kinetics. pseudo-second order implied adsorption of phenol was chemisorption (gao et al., 2022). the langmuir isotherm equation is used if the adsorption process is in the form of a single layer or monolayer and there is an interaction between the adsorbate molecules. the freundlich isotherm equation applies to adsorption processes that occur in several layers or multilayers so that there is no association and dissociation of the adsorbate molecules (liu et al., 2021). the results of the nial ldh, chitosan, and chitosan@nial ldh adsorption isotherm data can be seen in table 3. all adsorbents followed the freundlich equation adsorption isotherm model, seeing the correlation coecient (r2) value closer to the value of 1. the maximum adsorption capacity of nial ldh, chitosan, and chitosan@nial ldh is 25.445, 23.753, and 33.223 mg/g, respectively. comparison maximum capacities this work with other research in adsorption shown in table 4. table 4. comparison maximum capacities adsorption of phenol with other research adsorbent qmax (mg/g) reference bentonite 23.64 (ahmadi and igwegbe, 2018) 𝛼-fe2o3 21.93 (dehmani et al., 2020) claried sludge 1.052 (mandal and das, 2019) swnto 30.864 (de la luz-asunción et al., 2015) geo 28.986 (de la luz-asunción et al., 2015) lignite 6.216 (liu et al., 2021) natural clay 10.1 (dehmani et al., 2021a) zncl2-bfac 17.02 (sathya priya and sureshkumar, 2020) tea waste 7.62 (gupta and balomajumder, 2015) zn4al-ldh 7.73 (lupa et al., 2018) nial ldh 25.445 this work chitosan 23.753 this work chitosan@nial ldh 33.223 this work © 2022 the authors. page 533 of 535 utami et. al. science and technology indonesia, 7 (2022) 530-535 figure 5. pseudo-first order and pseudo-second order for adsorption of phenol figure 6. regeneration study of adsorbent based on figure 6, it can be seen that the adsorbent regeneration process decreased during the third regeneration. the percentage of phenol adsorbed using nial ldh, chitosan, and chitosan@nial ldh during the rst regeneration reached 47.821, 38.844, 48.859%, respectively. the increase in regeneration cycles causes a decrease in the percentage of adsorbed; sequentially, the percentage adsorbed during the fth regeneration reaches 3.545, 1.966, 4.309%, respectively. 4. conclusion modication of the nial ldh composite with chitosan was successful by characterization xrd, ftir and bet. the optimum ph of the nial ldh at ph 3, the optimum ph for chitosan and chitosan@nial ldh material is ph 5. the kinetic and isotherm model in the adsorption process is pseudosecond-order and freundlich model, respectively. the maximum adsorption capacity of nial ldh, chitosan, and chitosan@nialldhis25.445,23.753,and33.223mg/g, respectively. the increase in regeneration cycles causes a decrease in the percentage of adsorbed; sequentially, the percentage adsorbed during the fth regeneration reaches 3.545, 1.966, 4.309%, respectively. 5. acknowledgment the authors thank the research centre of inorganic materials and coordination complexes fmipa universitas sriwijaya for support and instrumental analysis. references ahmad, n., a. wijaya, amri, e. s. fitri, f. s. arsyad, r. mohadi, and a. lesbani (2022). catalytic oxidative desulfurization of dibenzothiophene by composites based ni/aloxide. science and technology indonesia, 7(3); 385–91 ahmadi, s. and c. a. igwegbe (2018). adsorptive removal of phenol and aniline by modied bentonite: adsorption isotherm and kinetics study. applied water science, 8(6); 1–8 al-ghouti, m. a., j. sayma, n. munira, d. mohamed, d. a. da’na, h. qiblawey, and a. alkhouzaam (2022). eective 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hypercrosslinked polymers with ultrafast adsorption rate as an ecient adsorbent for phenol removal. microporous and mesoporous materials, 336; 111836 © 2022 the authors. page 535 of 535 introduction experimental section chemicals and instrumentation synthesis of nial-ldh preparation chitosan@nial ldh adsorption of phenol result and discusssion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper electrochemical performance of galvanic cell with silver coated cathode in one compartment system using seawater as electrolyte gurum ahmad pauzi1,2, ahmad saudi samosir3, sri ratna sulistiyanti3, wasinton simanjuntak4* 1doctoral student at the faculty of mathematics and natural sciences, university of lampung, bandar lampung, 35145, indonesia2department of physics, faculty of mathematics and natural sciences, university of lampung, bandar lampung, 35145, indonesia3department of electrical engineering, faculty of engineering, university of lampung, bandar lampung, 35145, indonesia4department of chemistry, faculty of mathematics and natural sciences, university of lampung, bandar lampung, 35145 , indonesia *corresponding author: wasinton.simanjuntak@fmipa.unila.ac.id abstractthis research was carried out to evaluate the electrochemical performance of a galvanic cell using seawater as an electrolyte. the cellwas designed to have a volume of 200 ml and equipped with zn as an anode and ag-coated cu as a cathode (cu(ag)-zn system)in order to suppress the corrosion of cu. as a comparison, the same experiment with the use of uncoated cu as a cathode (cu-znsystem) was also conducted. to conduct the experiment, a system was assembled by connecting 20 cells in series and placed ina closed container filled with seawater. the experiment was run for 72 hours, divided into three 24-hour cycles, by replacing theseawater every 24 hours. the performance of the system was evaluated in terms of open circuit voltage, close circuit voltage, current,light intensity, internal resistance, and power. the experimental results show that the corrosion rate of cu coated with silver wassmaller than that of uncoated cu. compared to the performance of the cu-zn system, it was also found that the cu(ag)-zn systemproduced higher power and light intensity, which is in accordance with its smaller internal resistance. the overall experimental resultsindicate better performance of cu(ag)-zn system and this better performance is attributed to the significantly lower corrosion rateof cu(ag) cathode which signifies the role of ag layer to protect the cu from attack by seawater. as a result, the cu(ag)-zn systemmaintained the cathode corrosion rate with a ratio of 0.19. the percentage decrease of the ocv of the cu(ag)-zn system was 6.14%,the ccv on the third day was 0.99%, the current was 36.68%, and the power was 37.83%. keywordsseawater, silver-coated cathode, renewable energy received: 23 august 2022, accepted: 20 november 2022 https://doi.org/10.26554/sti.2023.8.1.25-31 1. introduction fromanelectrochemicalpointofview, seawater isaverypotent natural resource as a source of electrical energy. this potential is related to the high electrolyte content of seawater (stefano etal.,2002),whichmeansthatseawatercontainsa largeamount of chemical energy (chave, 1971). in principle, this chemical energy can be converted into electrical energy through an electrochemical process in a galvanic cell (nithya sivakami et al., 2019; la mantia et al., 2011). however, the development of galvanic cells with seawater as an electrolyte is still very limited, primarily due to two essential characteristics of seawater that are not easy to control. the sodium as an anode creates problems with safety and cost due to the reactivity and the dry assembly process. the modication of the use of sodium as an electrode was done by the open cathode system method. this is modifying a li-ion battery into a hybrid battery/fuel cell system with seawater using a ceramic membrane permeable nasicon (kim et al., 2014; kim et al., 2022). for this requirement, it is necessary to provide electricity from the outside through the charge and discharge process, as in the case of rechargeable batteries, so that it does not explicitly act as a source of energy. in classic electrochemistry, galvanic cell using cu-zn pair as electrodes is the most well-known system. as an anode, zn can be oxidized easily and has no surface passivation during the oxidation, therefore, the system has high eciency in producing current (poulin et al., 2022). in addition, zn is non-toxic and relatively cheap metal, and for these advantageous characteristics zn has been used in zinc-air batteries (zab) with seawater as an electrolyte (yu et al., 2020). the problem with cu-zn galvanic cells with the use of seawater is the corrosive nature of seawater (thierry et al., 2016; nejneru et al., 2019), leading to passivation of the cu electrode due to the production https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.25-31&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.25-31 pauzi et. al. science and technology indonesia, 8 (2023) 25-31 of cucl2 deposit on the surface of the metal. the consequence is that the cell will lose its performance. to reduce passivation, one eective way is to coat the metal with another metal that is more resistant to corrosion (reda et al., 2020; ameen et al., 2010), simple and low-cost (hakim and pangestu, 2022; giurlani et al., 2018). inthis research, thecucoatedwithagwasusedasacathode and paired with zn metal as an anode in the galvanic cell using seawater as an electrolyte. silver was used as a coating because thismetal ismoreresistant tocorrosionandtheagcl thatmight be formed on the surface is also conductive. to investigate the eect of coating, the performance of a galvanic cell with cu (ag)-zn electrode pair was compared to that of galvanic cell with electrode pair of cu-zn. the experiments were run for 72 hours and divided into three cycles byreplacing the seawater every 24 hours. the performance of the systems was evaluated in terms of corrosion rate, open circuit voltage, closed circuit voltage, current, light intensity, power, and internal resistance. the novelty of this research is the new method for low-cost electrodesbyasilver-coatedelectrode implemented inseawater and the investigation of electric variables by direct load devices. 2. experimental section 2.1 materials the materials used in this research are seawater, cu plate 7×4×0.05 cm, zn plate 7×4×0.02 cm, 12-volt 3 watts dc led lamp, water lter, agno3 0.02 m solution, 1% hno3 solution, and ethanol 96%. the tools used in this research are a multimeter, tl series digital scales, lux meter, glass baker, power supply, and water ltration unit. 2.2 methods 2.2.1 preparation of cu(ag) electrode the cu(ag) electrode was prepared by electroplating process using agno3 solution in an electrochemical cell with cu metal as the cathode and a carbon rod as the anode. prior to electroplating, the cu metal surface was cleaned with a 1% hno3 solution to remove any dirt from the surface, followed by cleaning with 96% ethanol to remove the hno3 adsorbed on the surface. electroplating was run with a voltage of 2 volts for 5 minutes. the electroplated cu was removed from the electrochemical cell, carefully rinsed with deionized water, and dried. 2.2.2 fabrication of electrochemical cell the electrochemical cell was fabricated from acrylic material with the dimension of 8×4×7 cm as shown in figure 1a. to conduct experiment, 20 cells were assembled in a closed container and connected in series as shown in figure 1b. 2.2.3 data acquisition circuit data acquisition was carried out in a circuit as depicted in figure 2. the circuit was used to determine electrical characteristics including open-circuit voltage (ocv) and close-circuit voltage (ccv), the current owing in a 12-volt dc 3-watt led load. the light intensity (lux) was measured at a distance of 10 cm from led load. at a distance of 10 cm. in this study, the experiments were performed for 72 hours with data acquisition at every hour and the seawater was replaced every 24 hours. the electrical characteristics generated were then used to calculate internal resistance (rin) using equation 1. rin = vocv −vccv i (1) where rin = internal resistance (kω),vocv = no-load voltage (open circuit voltage) in volt, vccv = voltage with load (close circuit voltage) in volt, i = current in ampere. 2.2.4 corrosion rate measurement in this study, the corrosion rate of the electrodes was determined using the weight-loss method and calculated using equation 2 (astm, 1999). r = km 𝜌at (2) where r = corrosion rate (mm /year), k = constant (8.76 x 104), 𝜌= density (gr/cm3), m = m0 − m1 = initial mass (gr) nal mass (gr), a = surface area of the electrode (cm2). 3. result and discussion 3.0.1 the corrosion rate of the electrode the corrosion rate of the electrodes was determined based on the weight loss after the electrodes were utilized for 72 hours, and the results are presented in table 1. table 1. corrosion rates of the electrodes after 72 hour cu-zn cu(ag)-zn cu (mm/year) zn (mm/year) cu (mm/year) zn (mm/year) 0.331 0.372 0.062 0.486 the experimental results in table 1 show that all electrodes are corroded with dierent corrosion rates including cu and silver-coated cu or cu(ag) used as cathodes. as can be seen in table 1, the corrosion rate of cu metal was much higher than that of silver-coated cu. the calculation of the corrosion rate ratio of cu(ag) to cu was 0.19, indicating a higher ability of ag metal to resist corrosion by seawater. in this case, the ag layer protected the cu metal surface, but seawater could still penetrate the protective metal layer. in the redox reaction concept of the electrochemical cell, the cathode functions as the site for reduction, and therefore theoretically no corrosion (oxidation) occurs at this electrode. however, in the case of seawater, in a previous study, it was reported that copper used as cathode was found to react with chloride ions to produce cucl (li et al., 2012; kear et al., © 2023 the authors. page 26 of 31 pauzi et. al. science and technology indonesia, 8 (2023) 25-31 figure 1. electrochemical cell used in this study: single cell (a) and assembly of 20 cell (b) figure 2. the electronic circuit electrical characteristics measurement 2004). similarly, formation of agcl was reported by jin et al. (2003) and sharif and dorranian (2015) in their study using ag metal as a cathode in an electrochemical cell with seawater as electrolyte. other investigators shi et al. (2018) conducted a studyto compare corrosion behaviorof pure cu and pure cuni-zn alloy in 3.5% nacl solution and articial seawater with the electrochemical impedance spectroscopy and potentiodynamicpolarization techniqueandreported thatcuexperienced more severe corrosion of than that of cu-ni-zn alloy. it was suggested that the reduced corrosion rate of alloyed cu was attributed to the existence of a protective layer, while on the surface of cu no such layer formed. the results obtained also indicate that the use of a cu(ag) cathode led to an increased corrosion rate of the zn electrode compared to the corrosion rate with the use of cu as a cathode. this is the eect of increased power produced by the cell. when the metal is covered with a dense dielectric layer with minimal defects, the interface between the metal surface and the electrochemical electrolyte solution generally has a high impedance. the layer acts as a dielectric in the capacitor. because most of the protective layer has small holes and other permeable defects, this is related to the homogeneity and roughness of the electrode surface and is often used to figure 3. open circuit voltage as a function of time for cu-zn and cu(ag)-zn systems study local corrosion of metal layers (chu et al., 2006). in the measurements that have been carried out, there is a relatively higher corrosion rate value on some cu (ag) plates compared to the average value. this shows that the electrolyte solution can still penetrate the layer at the location of the coating defect so that a corrosion reaction occurs on the metal substrate and the area on the layer. 3.0.2 electrical characteristic measurement as previously described, the rst series of experiments were conducted for 72 hours and specied as a short-term experiment. figure 3 represents the open circuit voltage (ocv) of cell using cu-zn and cu(ag)-zn as electrode pairs. during the experiment, seawater was replaced with fresh seawater every 24 hours. to summarize the results, the initial and nal values of ocv in each of the cycles are presented in table 2. in table 2, for every 24-hour cycle (one cycle), in the initial measurement, cu(ag)-zn is higher (17.93 volts) compared to the ocvin the cu-zn system (17.09 volts). in the rst cycle measurement, the initial voltages can withstand an average of 96.8% for the © 2023 the authors. page 27 of 31 pauzi et. al. science and technology indonesia, 8 (2023) 25-31 table 2. summary of the initial and final value of ocv cycle ocv of cu(ag)-zn system (volt) ocv of cu-zn system (volt) initial final initial final 1st 17.93 17.32 17.09 15.82 2nd 17.19 16.79 15.56 14.76 3rd 16.82 16.75 15.24 15.11 table 3. summary of ccv and current of system cycle cu(ag)-zn system cu-zn system ccv (volt) i (ma) ccv (volt) i (ma) initial final initial final initial final initial final 1st 8.18 8.01 2.32 1.22 7.99 7.88 1.50 0.52 2nd 8.11 8.00 1.65 1.13 7.98 7.86 1.07 0.46 3rd 8.06 7.98 1.51 1.04 7.98 7.82 1.03 0.33 table 4. summary of ligh intensity and power of system cycle cu(ag)-zn system cu-zn system light intensity (lux) power (mw) light intensity (lux) power (mw) initial final initial final initial final initial final 1st 39 21 19 9.79 27 11 11.98 4.1 2nd 27 20 13.41 9.01 21 9 8.52 3.63 3rd 27 16 12.2 8.27 18 6 8.2 2.55 cu(ag)-zn system, while for the cu-zn system it is 94.4%. with the progress of the experiment until the third cycle, the ocvin both systems decreased, but the trend observed for the cu-zn system was signicantly steeper, with decreased percent ratio was 11.59%, than that observed for the cu(ag)-zn system was 6.14%, implying that the cu(ag)-zn was signicantly more stable than the cu-zn system. this higher stability was attributed to the role of the ag layer in resisting seawater attack. figure 4 indicated the closed-circuit voltage (ccv) value and current (i) observed for the two systems during the 72 hours experimental time. the experiments were conducted with the load 12-volt 3 watt of led. to summarize the results of ccvand current in each of the cycles are presented in table 3. in table 3, during the rst measurement, the initial ccv was 8.18 volts for the cu(ag)-zn system higher than initial ccv for cu-zn (7.99 volts), as well as in the second and third cycles. each initial value for the cu(ag)-zn system was consistently higher than cu-zn system. the percentage reduction ratio of ccv of cu(ag)-zn on the third day was 0.99%, while cu-zn was 2.00%. the average percentage reduction ratio of the current of cu(ag)-zn was 36.68%, and cu-zn was 63.43%. this data indicated that the galvanic cell with silver plating on the cathode could produce tremendous energy than the uncoating cathode. what was unique about the graph in figfigure 4. closed circuit voltage and current as a function of time for cu-zn and cu(ag)-zn systems © 2023 the authors. page 28 of 31 pauzi et. al. science and technology indonesia, 8 (2023) 25-31 table 5. summary of internal resistance of system cycle internal resistance of cu(ag)-zn system internal resistance of cu-zn system initial final initial final 1st 4.27 7.62 5.99 15.25 2nd 5.51 7.83 7.04 14.89 3rd 5.73 8.52 7.12 22.4 figure 5. the experimental data of light intensity (a) and power system (b) ure 4, the chart pattern of these two systems was marked by a peak that rises dramatically at the change of seawater in each cycle. a sharp decrease in ccvand current during the rst ve hours then continued the graph at the end of the previous cycle. the drastic increase in ccv and currents were most likely due to high dissolved oxygen in the fresh seawater (thierry et al., 2016) and then reduction during galvanic process (guo et al., 2021). this high oxygen concentration has caused an increase in the rate of the oxidation reaction so that the ccv and current were increased. the experimental data of light intensity and power are shown in figure 5. the summary of both systems could be seen in table 4. in the initial measurement, the intensity of visible light of led 12 volt 3 watts was produced by cu(ag)zn 39 lux and cu-zn 27 lux, and in the third cycle, the light intensity on the cu(ag)-zn system was 16 lux, and on cu-zn, only 6 lux. the percentage of power loss looks quite dierent, 37.83% for cu(ag)-zn and 64.02% for cu-zn. this intensity graph has been the same as the ccvand current chart patterns in figure 4. the power was dropped due to the presence of deposits from the reaction of the cathode surface with the seawater electrolyte. the presence of cl-ions in seawater will cause cucl deposits to appear on the cu electrodes and agcl on the surface of the ag layer. cucl has a higher resistance than agcl, so the power decreased drastically in the cu-zn cell. the magnitude of the current serves to be able to calculate figure 6. rin in 72 hours measurement © 2023 the authors. page 29 of 31 pauzi et. al. science and technology indonesia, 8 (2023) 25-31 the internal resistance (figure 6) that is available in the galvanized cell. the summary of internal resistance can be seen in table 5. the resistance in cu(ag)-zn galvanic cells has smaller compared to cu-zn, with the average percent ratio increasing of resistance from cycle 1st to 3rd was 35.44%, compared with cu-zn 60.55%, so the power produced by cu(ag)-zn is greater. when the metal is in the electrolyte, a process occurs which is a combination of the oxidation reaction, and the appearance of an electrical double layer at the interface of the metal and electrolyte surface. this process is usually illustrated with a randles network. the randles equivalent network is one of the simplest and most commonly used electrochemical impedance network models to analyze electricity in electrolyte systems (kumar et al., 2019; xu et al., 2019; yavarinasab et al., 2021; saxena and srivastava, 2019; alavi et al., 2016). the internal resistance of galvanized cells is determined by several factors such as electrolyte resistance, resistance on the electrode surface as a result of chemical reactions and crystallization and deposition processes, capacitive double layers, resistance due to polarization between electrodes, and warburg impedance. the cu(ag) electrode has less plaque and deposition on the surface than cu, which indicates that cu immersed in seawater will react faster on the surface. this is possible because the sea contains mineral ions such as cl−, na+, so4 2−, mg2+, ca2+, k+, hco3−, br−, sr2+, b3+, f−, mo2+, and others. 4. conclusion silver-coated cathodes showed better performance than uncoated copper on galvanic cells. in silver coated electrodes, the electrical characteristics of ocv, ccv, current, power are higher and internal resistance is lower than in uncoated cathodes, so the system can be used longer to generate electrical energy. 5. acknowledgment the author would like to thank the system for information and management of research and community service, the ministry of education, culture, research, and technology, 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31 yu, j., c. x. zhao, j. n. liu, b. q. li, c. tang, and q. zhang (2020). seawater-based electrolyte for zinc-air batteries. green chemical engineering, 1(2); 117–123 © 2023 the authors. page 31 of 31 introduction experimental section materials methods preparation of cu(ag) electrode fabrication of electrochemical cell data acquisition circuit corrosion rate measurement result and discussion the corrosion rate of the electrode electrical characteristic measurement conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 1, january 2022 research paper set covering model using greedy heuristic algorithm to determine the temporary waste disposal sites in palembang putra bahtera jaya bangun1, sisca octarina1,2*, rizka aniza1, laila hanum3, fitri maya puspita1, siti suzlin supadi4 1mathematics department, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30662, indonesia 2graduate school of science, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30662, indonesia 3biology department, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30662, indonesia 4institute of mathematical sciences, university of malaya, kuala lumpur, 50603, malaysia *corresponding author e-mail: sisca_octarina@unsri.ac.id abstract optimizing the facility location has a vital role in providing services to the community. this study aims to determine the temporary waste disposal site (twds) in sako district, palembang city. the distance data between each twds in sako district is used to formulate the set covering model, consisting of the set covering location problem (sclp) model and the p-median problem model. the classical approach is made by solving both models using lingo 18.0 software. the greedy heuristic algorithm is used as the heuristic approach. based on the results and discussion, sako district consists of 4 villages and 9 twds. the sclp and pmedian problem models with lingo 18.0 software and the greedy heuristic algorithm show a difference. the study results suggest using the optimal solution resulting from the greedy heuristic algorithm because it can meet all requests in sako district. research shows that there are six optimal twds in sako district. we recommend adding 14 additional twds facilities in sako district to serve all requests. keywords facility location, temporary waste disposal site, set covering model, greedy heuristic algorithm received: 28 october 2021, accepted: 17 january 2022 https://doi.org/10.26554/sti.2022.7.1.98-105 1. introduction rapid population growth makes indonesia ranks 4th in population density (devi et al., 2016). one of the impacts of population density is the waste problem. waste is no longer used or leftover materials and objects that are not useful and thrown away by people everywhere. to overcome indiscriminate waste disposal, the government provides temporary waste disposal sites (twds) facilities. twds is a facility that every region must own in indonesia to maintain environmental cleanliness. this study discusses the twds placement in the sako district. according to the sako district strategic plan (2019), sako district consists of many housing complexes and has inadequate twds for the community. it is necessary to optimize the location of twds so that people can dispose of their waste in its place. the problem of processing and transporting waste in palembang city is regulated by the palembang city environment and hygiene service (dlhk). dlhk is in charge of managing hygiene issues. according to dlhk, there are nine o�cial twds in sako district. the government has obstacles in placing the location of twds. this study attempts to assist and facilitate the selection of twds. optimizing location placement is part of the optimization problem, especially the set covering problem (scp) (puspita et al., 2019). scp is a problem of integer programming to optimize the number and allocation of facility location points (kwon et al., 2020). scp in daily life includes allocating machines to the given task, assigning jobs to workers, optimizing the facility location to obtain optimal results, assigning garbage vehicle routes to the garbage collection site to optimize the distance and required costs, and others (cordeau et al., 2019; octarina et al., 2020; sitepu et al., 2019a; sitepu et al., 2019b; ye and kim, 2016). scp has several problems, including set covering location problem (sclp) and the p-median problem (amarilies et al., 2020; dzator and dzator, 2015; karataş et al., 2017). sclp aims to determine the optimum number of facilities from several available facilities (crawford et al., 2015; puspita et al., 2019). the p-median problem minimizes the total distance or time or average travel costs to the facility so that it is possible to make an optimal choice (tao et al., 2018). one of the heuristic algorithms for solving scp is the greedy heuristic algorithm. greedy heuristic algorithm is https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.1.98-105&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.1.98-105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 an algorithm that chooses the best solution for the facilities located at each step. according to amarilies et al. (2020), the greedy heuristic algorithm is the most feasible way to get a problem solution from the sclp model and p-median problem. there are several steps to apply the greedy heuristic algorithm, including �nding candidates that include requests, then looking for facilities to make replacements, if and only if more than one facility has been allocated. this algorithm removes every selected candidate and replaces it with every non-selected candidate location. according to syakina and nurdiati (2021), the greedy heuristic algorithm is a heuristic method that �nds the optimal solution for large-scale and complicated problems. determination of the twds location is completed using the exact approach and developed by the heuristic method to produce a more precise and faster solution. several previous studies related to scp, especially in determining the public facility location, have been done (ahmadijavid et al., 2017; ardiansyah and mardlijah, 2019; çalık and fortz, 2019; karatas and yakıcı, 2018; silva and cunha, 2017; sitepu et al., 2019a; sitepu et al., 2019b). meanwhile, research on greedy heuristics has been carried out by min and xu (2016) and amarilies et al. (2020). amarilies et al. (2020) used the greedy heuristic algorithm to determine the public facility location and stated that this algorithm could provide an accurate optimal solution. so far, researches on scp have focused solely on modeling and classical solutions (ahmadi-javid et al., 2017; berman et al., 2019; kinsht and petrunko, 2020; lutter et al., 2017; wolf, 2019). a few researchers focused on heuristic solutions. therefore, this research is aimed to complete the set covering model with the greedy heuristic algorithm to obtain the optimal twds location in sako district, palembang city. 2. methods in this section, we discussed the method used in this research. a brief discussion of model sclp, p-median problem, and a short description of the greedy heuristic algorithm can be seen in this section. the steps of this research are listed as follows: 1. collect the names of twds in sako district from dlhk palembang city. 2. measure the distance between each twds in sako district, palembang city using google maps. 3. de�ne variables and parameters for the sclp model and p-median problem. 4. formulate the sclp and the p-median problem model. 5. solve the sclp and the p-median problem model using lingo 18.0 software. 6. implement the greedy heuristic algorithm to solve the model. 7. analyze the solution. 2.1 set covering location problem (sclp) sclp is a problem in the distribution system that aims to �nd the optimal number of facility locations to serve all demand points (sitepu et al., 2019b). the sclp model can be written as follows: minimize zsclp = ∑ j∈j aj (1) subject to ∑ j∈j aj ≥ 1,∀i ∈ i (2) aj ∈ {0, 1},∀j ∈ j (3) where zsclp = the number of facility location i = the set of demand location j = the set of facility location aj = { 1; if a twds is located at j-th location 0;otherwise the objective function (1) minimizes the number of facility locations. constraint (2) ensures that at least one facility meets each request point, and constraint (3) states that the decision variables are binary. 2.2 p-median problem one of the fundamental problems of discrete location theory to determine point p in a facility such that the sum of the distances from other points to the nearest chosen point p is minimal is called the p-median problem. the p-median problem search is carried out across a �nite set of points. the p-median problem aims to determine the point p (center) with the sum of the distances from n demand point to the nearest p center (tao et al., 2018). according to ahmadi-javid et al. (2017), the mathematical formulation of the p-median problem model can be written as follows: minimize z p−median = ∑ i∈i ∑ j∈j di jbi j (4) subject to ∑ j∈j bi j = 1,∀i ∈ i (5) ∑ j∈j aj = p (6) bi j ≤ aj ,∀i ∈ i ,∀j ∈ j (7) © 2022 the authors. page 99 of 105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 aj ∈ {0, 1}, bi j ∈ {0, 1} (8) with z p−median = minimum distance from demand location to facility location i = the set of demand location j = the set of facility location p = number of facility dij = distance between i and j location aj = { 1; if a facility is located at j-th location 0;otherwise bi j = { 1; if a demand in i location is located at j-th location 0;otherwise 2.3 greedy heuristic algorithm the greedy heuristic algorithm is one of the algorithms used to solve optimization problems. greedy’s algorithm aims to locate facilities without capacity, known as deletion. this algorithm is executed by determining the optimal facility location point. determining the optimal point is de�ned as the marginal cost of the objective function when each double route of transportation is removed from the facility location (katayama, 2019). this algorithm is the most feasible way to generate solutions from the sclp and p-median problem model. there are several steps in greedy heuristic algorithm, including determining candidate sites that include demands, then looking for facilities to make replacements, if and only if more than one facility has been located. the greedy heuristic algorithm uses a model from sclp. the steps in the greedy heuristic algorithm to get the optimal solution are 1. if ci= 0, ∀i, ai= 1, where ci is the objective function coe�cient, then eliminate all constraints ai which has a coe�cient of 1. 2. if ci > 0, ∀i and ai have no coe�cient 1 in any remaining constraints, then ai= 0 3. for the remaining variables, calculate cid1 where di is the number of constraints ai, which appears with a coe�cient of 1. choose the minimum variable cid1 and the set ai has a coe�cient of 1. 4. if there are no more constraints, all variable sets remaining 0 are terminated; otherwise, repeat step (1). 3. results and discussion the list of villages names, twds names, and the distance between each twds can be seen in tables 1 and 2. table 1 describes the twds names in each village in sako district. sukamaju village has 3 twds, namely twds ganda subrata in front of yuka housing, twds pusri sukamaju housing, and twds vila kenten complex. meanwhile, sako village has 2 twds, namely twds bsd complex and twds griya musi sako market. sialang village has 3 table 1. the list of villages and twds names villages names twds names sukamaju village twds ganda subrata in front of yuka housing twds pusri sukamaju housing twds vila kenten complex sako village twds bsd complex twds griya musi sako market sialang village twds behind satelit murni market twds east musi raya street twds west musi raya street sako baru village twds north musi raya street twds, namely twds behind satelit murni market, twds east musi raya street, and twds west musi raya street. sako baru village has 1 twds, namely twds north musi raya street. the de�nition of variables and parameters for twds and villages in sako district can be seen in table 2. table 2 states that a1 is twds ganda subrata in front of yuka housing, a2 is twds pusri sukamaju housing, and so on. table 3 states the distance data between each twds in sako district. according to the regulation of the minister of public works of the republic of indonesia article 29 paragraph (3) regarding the implementation of waste infrastructure and facilities in the handling of household waste and types of household waste, the maximum distance between each twds is 500 meters. this distance data was obtained using google maps. table 2. de�ning variables and parameters variables de�nition a1 twds ganda subrata in front of yuka housing a2 twds pusri sukamaju housing a3 twds vila kenten complex a4 twds bsd complex a5 twds behind satelit murni market a6 twds north musi raya street a7 twds east musi raya street a8 twds west musi raya street a9 twds griya musi sako market b1 sukamaju village b2 sako village b3 sialang village b4 sako baru village table 3 states that d12 is the distance from twds ganda subrata in front of yuka housing (a1) to twds pusri sukamaju housing (a2) is 1,800 meters, d13 is the distance from twds ganda subrata in front of yuka housing (a1) to twds vila kenten complex (a3) is 1,700 meters and so on. © 2022 the authors. page 100 of 105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 table 3. distances between each twds in sako district dij 1 2 3 4 5 6 7 8 9 1 0 1800 1700 4300 4900 3300 3700 3500 4200 2 1800 0 1100 3500 4100 2500 2900 2700 3400 3 1700 1100 0 3100 3600 2000 2400 2200 2900 4 4300 3500 3100 0 2800 2500 2900 2700 2600 5 4900 4100 3600 2800 0 1600 1200 1500 500 6 3300 2500 2000 2500 1600 0 450 450 950 7 3700 2900 2400 2900 1200 450 0 300 500 8 3500 2700 2200 2700 1500 450 300 0 800 9 4200 3400 2900 2600 500 950 500 800 0 3.1 set covering location problem (sclp) model of twds in sako district based on model (1)-(3), the sclp model of twds in sako district can be seen in model (9), with constraints (11)-(18). minimize zsclp = a1+a2+a3+a4+a5+a6+a7+a8+a9 (9) subject to a1 ≥ 1 (10) a2 ≥ 1 (11) a3 ≥ 1 (12) a4 ≥ 1 (13) a5 + a9 ≥ 1 (14) a6 + a7 + a8 ≥ 1 (15) a6 + a7 + a8 + a9 ≥ 1 (16) a5 + a7 + a9 ≥ 1 (17) a1, a2, a3, a4, a5, a6, a7, a8, a9 ∈ {0,1} and integer (18) model (9) minimizes the number of candidate locations. constraints (11)-(17) are the constraints for each demand point that has a distance ≤ 500 meters, and constraint (18) states that each variable is binary. by using the lingo 18.0 software, the optimal solution of twds location states that a1 = a2 = a3 = a4 = a8 = a9 = 1 which means that the candidate locations should be in 6 twds locations as follows: 1. twds ganda subrata in front of yuka housing 2. twds pusri sukamaju housing 3. twds vila kenten complex 4. twds bsd complex 5. twds west musi raya street 6. twds griya musi sako market 3.2 p-median problem model of twds in sako district the p-median problem model uses data on the location of twds and the demand from the villages in sako district. the location of twds is indicated by xj, and the location of the villages is denoted by yi. based on the results of the sclp model, there are six optimal twds located in 4 villages in sako district. the p-median problem model is formulated according to equation (4) and constraints (5) to (8). the distance data from the facility point to the demand point is shown in table 4. table4. distance between villages and twds in sako district dij 1 2 3 4 8 9 1 750 1100 1100 4300 3100 3600 2 4200 3300 2800 2600 800 550 3 3800 2800 2400 3500 1400 650 4 4000 3100 2600 2500 950 800 table 4 states that d11 is the distance from sukamaju village (b1) to twds ganda subrata in front of yuka housing (a1) is 750 meters, d12 is the distance from sukamaju village (b1) to twds pusri sukamaju housing (a2) is 1,100 meters, and so on. furthermore, for the formulation of the objective function, the notation yij is used, which states the request in village i is assigned to the j− th twds. the p-median problem model of twds in sako district is stated in model (19)–(32). minimize z p−median =750b11 +1100b12 +1100b13 +4300b14+ 3100b18 +3600b19 +4200b21 +3300b22+ 2800b23 +2600b24 +800b28 +550b29+ 3800b31 +2800b32 +2400b33 +3500b34+ 1400b38 +650b39 +4000b41+3100b42+ 2600b43 +2500b44 +950b48 +800b49 (19) © 2022 the authors. page 101 of 105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 b11 +b12 +b13 +b14 +b18 +b19 = 1 (20) b21 +b22 +b23 +b24 +b28 +b29 = 1 (21) b31 +b32 +b33 +b34 +b38 +b39 = 1 (22) b41 +b42 +b43 +b44 +b48 +b49 = 1 (23) a1 + a2 + a3 + a4 + a8 + a9 = 6 (24) b11, b21, b31, b41 ≤ a1 (25) b12, b22, b32, b42 ≤ a2 (26) b13, b23, b33, b43 ≤ a3 (27) b14, b24, b34, b44 ≤ a4 (28) b18, b28, b38, b48 ≤ a8 (29) b19, b29, b39, b49 ≤ a9 (30) b11, b12, b13, b14, b18, b19, b21, b22, b23, b24, b28, b29, b31, b32, b33, b34, b38, b39, b41, b42, b43, b44, b48, b49 ≥ 0 and integer (31) a1, a2, a3, a4, a8, a9 ≥ 0 and integer (32) the objective function (19) minimizes the total distance between villages and twds. constraints (21)-(24) are the constraints for demand location. constraint (25) shows the number of facility locations. meanwhile, constraints (26)-(30) ensure that the demand locations correspond to the optimal twds from the sclp solutions. each variable is binary and shown in constraints (31)-(32). the optimal distance based on the solution of p-median problem model is 2,750 meters with b11= b29= b39= b49=1 which mean: 1. the demand in sukamaju village (b1) is allocated at twds ganda subrata in front of yuka housing (a1). 2. the demand in sako village (b2) is allocated at twds griya musi sako market (a9). 3. the demand in sialang village (b3) is allocated at twds griya musi sako market (a9). 4. the demand in sako baru village (b4) is allocated at twds griya musi sako market (a9). 3.3 implementation of the greedy heuristic algorithm in solving the scp model completing the scp model used the distance data in table 3 to obtain tables 5 and 6. the process of implementing the greedy heuristic algorithm to the model is stated as follows. table 5. objective function of sclp model twds 1 2 3 4 5 6 7 8 9 parameter ci 1 1 1 1 1 1 1 1 1 the yellow line shows the twds in sako district. the green line shows the parameter ci, where ci is the objective function coe�cient of each, i = 1, 2, 3, 4, 5, 6, 7, 8, 9, all of which are 1. table 6. constraints of sclp model constraint a1 a2 a3 a4 a5 a6 a7 a8 a9 first 1 0 0 0 0 0 0 0 0 second 0 1 0 0 0 0 0 0 0 third 0 0 1 0 0 0 0 0 0 fourth 0 0 0 1 0 0 0 0 0 fifth 0 0 0 0 1 0 0 0 1 sixth 0 0 0 0 0 1 1 1 0 seventh 0 0 0 0 0 1 1 1 1 eighth 0 0 0 0 0 1 1 1 0 ninth 0 0 0 0 0 0 1 0 1 table 6 explains that the coe�cient constraint with a value of 1 indicates the distance between twds is less than 500 meters. in comparison, the coe�cient constraint with a value of 0 means the distance between twds is more than 500 meters. first iteration step 1 if ci=0, ∀i, ai= 1, where ci is objective function coe�cient, i = 1, 2, 3, 4, 5, 6, 7, 8, 9. eliminate all constraints where ai has a coe�cient of 1. we go to step 2 because all values of ci in the objective function are greater than 0. step 2 if ci > 0, ∀i and ai does not have a coe�cient of 1 in any of the remaining constraints then ai= 0. in this step, �rst calculate di, where di is the number of constraints xi with a coe�cient of 1 to obtain table 7. table 7. renewal constraints phase 1 constraint a1 a2 a3 a4 a5 a6 a7 a8 a9 first 1 0 0 0 0 0 0 0 0 second 0 1 0 0 0 0 0 0 0 third 0 0 1 0 0 0 0 0 0 fourth 0 0 0 1 0 0 0 0 0 fifth 0 0 0 0 1 0 0 0 1 sixth 0 0 0 0 0 1 1 1 0 seventh 0 0 0 0 0 1 1 1 1 eighth 0 0 0 0 0 1 1 1 0 ninth 0 0 0 0 0 0 1 0 1 di 1 1 1 1 2 3 4 3 3 it can be seen in table 7, there is no constraint ai = 0, so go to step 3. step 3 for the remaining variables, calculate cidi where di is the number of constraints ai with a coe�cient of 1. choose the © 2022 the authors. page 102 of 105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 minimum variable cidi and the set ai has a coe�cient of 1. the calculation results can be seen in table 8. table 8. renewal constraints phase 2 constraint a1 a2 a3 a4 a5 a6 a7 a8 a9 first 1 0 0 0 0 0 0 0 0 second 0 1 0 0 0 0 0 0 0 third 0 0 1 0 0 0 0 0 0 fourth 0 0 0 1 0 0 0 0 0 fifth 0 0 0 0 1 0 0 0 1 sixth 0 0 0 0 0 1 1 1 0 seventh 0 0 0 0 0 1 1 1 1 eighth 0 0 0 0 0 1 1 1 0 ninth 0 0 0 0 0 0 1 0 1 di 1 1 1 1 2 3 4 3 3 ci 1 1 1 1 1 1 1 1 1 ci di 1 1 1 1 0.5 0.333 0.25 0.333 0.333 columns and rows in blue show the removal of coe�cient 1 and the updating of the values of di and ci di . as shown in table 9, the minimum cidi is found at a7, so a7= 1. remove all constraints on a7 which has a coe�cient of 1 i.e. 6, 7, 8, dan 9. because some constraints are removed, the values of di and ci di are also updated, we got tables 9 and 10. table 9. renewal objective function phase 1 twds 1 2 3 4 5 6 7 8 9 parameter ci 1 1 1 1 1 1 1 1 1 first solution 1 table 10. elimination of constraints phase 3 constraint a1 a2 a3 a4 a5 a6 a7 a8 a9 first 1 0 0 0 0 0 0 0 0 second 0 1 0 0 0 0 0 0 0 third 0 0 1 0 0 0 0 0 0 fourth 0 0 0 1 0 0 0 0 0 fifth 0 0 0 0 1 0 0 0 1 di 1 1 1 1 1 0 0 1 ci 1 1 1 1 1 1 1 1 ci di 1 1 1 1 1 0 0 1 in table 10, it can be seen in the blue column showing that the deletion of a7 resulted in the value of constraint a6 and a8 being 0. step 4 if there are no more constraints, all variable sets remaining 0 are terminated, otherwise repeat step 1. step 4 is not yet applicable because in the �rst iteration there are still many obstacles, so it is repeated to step 1. the process continues until iteration 6 and is obtained in table 11. table 11 shows that there are no remaining constraints, so the iteration stops. in this sixth iteration, there are no remaining constraints, so the iteration is complete. the optimal solutions obtained table 11. renewal objective function phase 1 twds 1 2 3 4 5 6 7 8 9 parameter ci 1 1 1 1 1 1 1 1 1 first solution 1 second solution 0 1 0 third solution 1 0 1 0 fourth solution 1 0 1 0 0 fifth solution 1 1 0 1 0 0 fifth solution 1 1 1 0 1 0 0 seventh solution 1 1 1 1 0 1 0 0 eighth solution 1 1 1 1 1 0 1 0 0 from the greedy heuristic algorithm are a1= a2= a3= a4= a5= a7= 1 which mean the optimal twds are: 1. twds ganda subrata in front of yuka housing at sukamaju village. 2. twds pusri sukamaju housing at sukamaju village. 3. twds vila kenten complex at sukamaju village. 4. twds bsd complex at sako village. 5. twds behind satelit murni market at sialang village. 6. twds east musi raya street at sialang village. after completing the scp model with the greedy heuristic algorithm, the optimal twds in sukamaju, sako, and sialang villages is obtained, so it is necessary to recommend a new twds in sako baru village in sako district, palembang city. several other locations are still not optimal, so it is recommended that there are an additional 14 new twds facilities in sako district to serve all demands. figure 1. the optimal twds in sako district 4. conclusion based on the results and discussion on determining the optimal location of twds in sako district, it can be concluded that © 2022 the authors. page 103 of 105 bangun et. al. science and technology indonesia, 7 (2022) 98-105 the sclp model produces six optimal twds that can be used and utilized by the community in sako district. while in the p-median problem model, it is found that the request for 4 villages in sako district is placed at the closest facility locations to minimize the distance traveled. the implementation of the greedy heuristic algorithm shows several di�erences in the optimal location obtained compared to the results of the scp model. this study recommends the results of the greedy heuristic algorithm as the optimal solution for placing twds in sako district. the optimal twds can be seen in figure 1. further research can apply other heuristic methods, such as the genetics and the hill climbing method. the next model can add other factors such as the capacity of twds and waste transportation route. 5. acknowledgement the research or publication of this article was funded by dipa of public service agency of sriwijaya university 2021. sp dipa-023.17.2.677515/2021, on november 23, 2020. in accordance with the rector’s decree number: 0010/un9/sk.lp 2m.pt/2021, on april 28, 2021. references ahmadi-javid, a., p. seyedi, and s. s. syam (2017). a survey of healthcare facility location. computers and operations research, 79; 223–263 amarilies, h. s., a. p. redi, i. mu�dah, and r. nadlifatin (2020). greedy heuristics for the maximum covering location problem: a case study of optimal trashcan location in kampung 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(2019). location covering models: history, applications and advancements (advances in spatial science) international journal of geographical information science, 633(11); 2334–2335 ye, h. and h. kim (2016). locating healthcare facilities using a network-based covering location problem. geojournal, 81(6); 875–890 © 2022 the authors. page 105 of 105 introduction methods set covering location problem (sclp) p-median problem greedy heuristic algorithm results and discussion set covering location problem (sclp) model of twds in sako district p-median problem model of twds in sako district implementation of the greedy heuristic algorithm in solving the scp model conclusion acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper extension of exponential pareto distribution with the order statistics: some properties and application to lifetime datasets adewunmi olaniran adeyemi1*, ismail adedeji adeleke2, eno emmanuella akarawak1 1department of statistics, faculty of science, university of lagos, lagos, 101017, nigeria2department of actuarial science and insurance, university of lagos, lagos, 101017, nigeria *corresponding author: adewunyemi@yahoo.com abstractthe exponential pareto (ep) model has been extended by applied and theoretical statisticians for wider applications and newknowledge using different techniques but the weibull-x technique has not been considered. this article proposed a new extension ofthe ep model called the weibull-exponential pareto (wep) distribution to provide better modeling that fits real-life datasets and toexplore the statistical theory of order statistics from the proposed distribution. statistical properties investigated include the shannonand renyi entropies; the moments and moment generating function. distribution of order statistics and the moment of orderstatistics were derived including the mean and variance of order statistics. wep distribution has unimodal, decreasing, and increasingfailure rates; and it can be negatively or positively skewed and approximately symmetric with the potential for fitting platykurtic,mesokurtic, and leptokurtic lifetime data. the parameters of the distribution were estimated using the method of maximum likelihoodestimation (mle), which was examined for consistency through a simulation study. the performance of the proposed distributionwas investigated by application to flood peaks exceedances and some lifetime datasets from engineering. the results from dataanalysis using the r-software revealed that the wep distribution has the potential to provide a superior model that fits the three datasets better than some notable existing distributions and previous extensions of the ep model in the literature. the statistical propertyof order statistics extended in the study established some important results that characterized some notable lifetime distributions inthe literature. keywordsexponential pareto model, weibull-x technique, weibull-exponential pareto distribution, shannon and renyi entropies, distributionof order statistics, moment of order statistics received: 9 november 2022, accepted: 6 february 2023 https://doi.org/10.26554/sti.2023.8.2.265-279 1. introduction statisticians and researchers in general are motivated by burning desires to discover new distributions that are adequate and more flexible in terms of application to real-life problems. extension of classical distributions and some other existing models have been suggested and successfully implemented in the statistical literature using various techniques. previous efforts towards the actualization of the objectives are contained in lee et al. (2007) using the beta-generator technique to extend the weibull distribution, the t-x family of distribution was introduced by alzaatreh et al. (2013b) and by taking t to be a weibull distribution random variable, the weibull-x was defined by alzaatreh et al. (2013b) as a sub-family of the t-x family. several important distributions have been proposed using the weibull-x technique including the weibull-pareto model by (alzaatreh et al., 2013a) . the weibull-rayleigh distribution was developed by akarawak et al. (2013) and later by ahmad et al. (2017) with different motives and diverse applications when x follows the rayleigh random variable. al kadim and boshi (2013) defined and studied the exponential pareto (ep) distribution with the cumulative distribution function (cdf) and probability density function (pdf) defined respectively as f(x) = 1 − e− 𝛽 ( x k ) \ (1) f (x) = 𝛽 \ k ( x k )\−1 e− 𝛽 ( x k ) \ ; 𝛽 , k, \ > 0 > 0;x > 0 (2) 𝛽 ,k,\ are the parameters of the distribution the ep distribution has further gained extensive studies with applications https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.265-279&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.265-279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 from luguterah and nasiru (2015) , using the quadratic rank transmutation map (qrtm) to develop the transmuted exponential pareto (tep) distribution, the beta-g framework was used by aryal (2019) and later by rashwan and kamel (2020) for the construction of beta exponential pareto (bep) model. kumaraswamy exponential pareto (kep) distribution was introduced by elbatal and aryal (2017) using the kum-g technique and most recently, the gompertz-g technique was explored for developing the gompertz exponential pareto distribution by (adeyemi et al., 2021) . dikko and faisal (2017) proposed the generalized exponential weibull (gew) distribution and the topp leone weibull distribution (tlwd) was introduced by (tuoyo et al., 2021) . in another dimension, the new weibull pareto distribution (nwp) was developed by nasiru and luguterah (2015) ; and thereafter, with the aid of the qrtm, tahir and akhter (2018) extended the nwp to produce the transmuted new weibull pareto (tnwp) and most recently, aljuhani et al. (2022) introduced the alpha power exponentiated new wuibull pareto distribution from the nwp model and hassan et al. (2022) developed the kumaraswamy extended exponential (kwee). nevertheless, instances abound where these existing distributions have not been able to explain some of the real-life problems adequately through the analysis of their corresponding datasets, making this study gap a challenge that is constantly been addressed by researchers. this current study is aimed at exploring the versatility of the weibull distribution as a generator by using the weibullx technique to extend the ep model. the proposed model called the weibull exponential pareto (wep) distribution is expected to provide more flexibility for addressing various forms of kurtosis and skewness associated with real-life datasets describing some of the random events in our environments. the remaining part of the study is organized as follows; section 2 is devoted to describing and developing the proposed distribution with the sub-models and some of the statistical properties. section 3 discussed the procedure for the estimation of parameters and simulation study. applications to three real-life datasets were carried out to assess the importance of the distribution in section 3. section 4 concludes the work and section 5 for acknowledgment. 2. experimental section this section is used for the design of the new distributions from some existing resources in the statistical literatures; properties of the wep distribution constructed are also investigated. 2.1 materials and method a new method of generating continuous distribution proposed by alzaatreh et al. (2013b) has the cdf for the t-x class of distribution defined as g(x) = ∫ −log(1−f (x)) 0 r(t)dt = r{−log(1 − f(x))} (3) where r(t) the cdf of a non-negative continuous random variable is t defined on [0,∞) and f(x) is the cdf of a random variable x. the pdf associated with equation (3) is given by, g(x) = f (x) 1 − f(x) r{−log(1 − f(x))} (4) where r(t) is the pdf of random variable t and the derivative of r(t). let t be a random variable from the weibull distribution with parameters 𝛼 and 𝛾 having the cdf given by, r(t) = 1 − exp ( − ( t 𝛾 )𝛼 ) ; 𝛼, 𝛾 > 0, t > 0 (5) the cdf of the weibull-x family is derived by inserting t=-log(1-f(x)) into equation (5) to obtain alzaatreh and ghosh (2015) given by g(x) = 1 − exp ( − ( −log(1 − f(x)) 𝛾 )𝛼 ) (6) and the pdf can be derived by taking the first derivative of equation (6) to get g(x) = 𝛼 𝛾 f (x) 1 − f(x) ( −log(1 − f(x)) 𝛾 )𝛼−1 exp( − ( −log(1 − f(x)) 𝛾 )𝛼 ) (7) 2.2 the new extension of exponential pareto distribution the cdf of the proposed lifetime distribution called weibull exponential pareto (wep) distribution when x follows the ep distribution in equation (1) is developed as; g1(x) = 1 − exp ( − ( 𝛽 ( x k )\ 𝛾 )𝛼 ) (8) then by replacing 𝛽 ⁄𝛾 with _ , the cdf in equation (8) can be written as g(x) = 1 − exp ( − ( _ ( x k )\ )𝛼 ) (9) the derivative of equation (9) is the corresponding pdf of the weibull exponential pareto (wep) distribution given by g(x) = 𝛼_ \ k ( x k )\−1 ( _ ( x k )\ )𝛼−1 exp ( − ( _ ( x k )\ )𝛼 ) ; 𝛼, _ , \ , k > 0;x > 0 (10) a random variable x that follows the weibull exponential pareto distribution with parameters 𝛼,_ ,\, and k is characterized with the density function g(x) in equation (10) and is denoted by wep (𝛼,_ ,\,k). © 2023 the authors. page 266 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 2.3 sub-models of wep distribution the important sub-models derived from the proposed distribution are presented in table 1. plots of the shapes for the cdf and pdf of the distribution for some parameter values are displayed in figure 1. figure 2 provides the visual view of the shapes of the hazard rate function of the proposed distribution for some values of the parameter (𝛼,_ ,\,k). figure 1. plots of the cdfs and pdfs of wep distributions for some values of the parameters figure 2. plots of hazard rate functions of wep distributions for some values of the parameters 2.4 properties of the weibull exponential pareto distribution some of the properties of the distribution are discussed in this section 2.4.1 the reliability and the hazard rate function the reliability function is defined in similar works including adeyemi et al. (2021) and is given by s(x) = 1 −g(x) = exp ( − ( _ ( x k )\ )𝛼 ) (11) the hazard rate function is derived from equation (9) and equation (10) and is given by h(x) = g(x) 1 −g(x) = 𝛼_ \ k ( x k )\−1 ( _ ( x k )\ )𝛼−1 (12) 2.4.2 asymptotic behavior of wep the asymptotic properties of the proposed model are investigated by taking limits of the density function, cdf, and the hazard rate function as x→∞ and as x→0. proposition 1: the limit of the wep density function as x→∞ is 0 and as x→0 is; lim x→0 g(x) =  0 , 𝛼\ > 1 _ k , 𝛼\ = 1 ∞ , 𝛼\ < 1 proof: lim x→∞ g(x) = lim x→∞  𝛼_ \ k ( x k )\−1 {_ ( xk )\ }𝛼−1 exp ( −{_ ( x k )\ }𝛼 )  = 0 lim x→0 g(x) = lim x→0 𝛼_ \ k ( x k )\−1 {_ ( x k )\ }𝛼−1 exp ( −{_ ( x k )\ }𝛼 ) the limit of exp ( − { _ ( x k )\ }𝛼 ) as x→0 is 1, we now have a situation where as x→0 when \>1, 𝛼\>1 it becomes 0, when \<1, 𝛼\<1 it becomes ∞ ; when 𝛼=\=1 we have limx→0 _ k exp (-{_ ( x k )}) which reduces to constant _k . this completes the proof. proposition 2: the limit of wep cdf as x→∞ is 1 and as x→0 is 0 proof: lim x→∞ g(x) = lim x→∞ [ 1 − exp ( −{_ ( x k )\ }𝛼 ) ] = 1 − 0 = 1 lim x→0 g(x) = lim x→0 [ 1 − exp ( −{_ ( x k )\ }𝛼 ) ] = 1 − 1 = 0 proposition 3: the limit of the wep hazard rate function as x→∞ is ∞ and as →0 is given by 0 , 𝛼\ > 1 _ k , 𝛼\ = 1 ∞ , 𝛼\ < 1 proof: the hazard rate function is defined as, h(x) = 𝛼_ \ k ( x k )\−1 { _ ( x k )\ }𝛼−1 lim x→∞ h(x) = ∞ 0 = ∞ when 𝛼\ > 1; lim x→∞ h(x) = ∞ 0 = ∞ when 𝛼\ < 1. the asymptotic limits when 𝛼\ = 1 is also lim x→∞ h(x) = _ k ( 1 0 ) = ∞. © 2023 the authors. page 267 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 table 1. sub-models of wep distribution 𝛼 _ \ k reduced model author/references 𝛼 12𝛽 2 k weibull-rayleigh ahmad et al. (2017) 𝛼 1p 2 1 weibull-rayleigh akarawak et al. (2017) 1 _ \ k exponential pareto al kadim and boshi (2013) 2 1 8𝜎2 2 𝛽 rayleigh rayleigh ateeq et al. (2019) 1 _∗2 2 k exponential rayleigh new 1 1 _ k exponential exponential new 1 12 2 k rayleigh rayleigh (1896) 1 12 \ k weibull weibull (1951) asymptotes of hazard rate as x→0 lim x→0 h(x) = 0 1 = 0 when 𝛼\ > 1; lim x→0 h(x) = ∞ 1 = ∞ when 𝛼\ < 1. the asymptotic limits when 𝛼\ = 1 is also lim x→0 h(x) = _ k , the proof is completed. proposition 4: let g(x) be the pdf and h(x) the hazard rate function of wep distribution then, as x→0 we have g(0)=h(0). proof: combining results from propositions (1) and (3) established the proof and is given by, lim x→0 h(x) =  0 , 𝛼\ > 1 _ k , 𝛼\ = 1 ∞ , 𝛼\ < 1 = lim x→0 g(x) 2.4.3 quantile function, simulation, and median let u be a uniform random variable on the interval (0, 1); the quantile function is defined by q(u)=g−1 (x), and the wep distribution has the quantile function derived and presented as; q(u) = k { 1 _ [ −log(1 − u) 1 𝛼 ] } 1 \ (13) let x be a random variable from the weibull exponential pareto distribution, simulation can be done through the inverse transformation of the variable using uniform interval u (0, 1) and the random variable x taking as, x = k { 1 _ [ −log(1 − u) 1 𝛼 ] } 1 \ (14) the median of the wep can be derived by substituting u=0.5 in equation (14) to get median = k { 1 _ [ −log(0.5) 1 𝛼 ] } 1 \ (15) 2.4.4 moments of wep distribution theorem 1: let x be a continuous random variable from the wep distribution with density function g(x), then the rth moment about the origin is given by; ` (r) = kr ( 1 _ )r/\ γ ( r 𝛼\ + 1 ) (16) proof : the moment of x is defined as e(xr)= ∫ ∞ −∞ x r g(x)dx e(xr) = ∫ ∞ 0 xr 𝛼_ \ k ( x k )\−1 { _ ( x k )\ }𝛼−1 exp ( − { _ ( x k )\ }𝛼 ) dx (17) let u = _ ( x k )\ which implies that x = k ( u _ )1/\ then substitute new variables so that du dx = _ \ k ( x k )\−1 and du = _ \ k ( x k )\−1 dx e(xr) = ∫ ∞ 0 ( k ( u _ )1/\ )r 𝛼_ \ k ( x k )\−1 u𝛼−1exp(−u𝛼) 1 _ \ k ( x k )\−1du, = 𝛼kr ( 1 _ )r/\ ∫ ∞ 0 u r \ +𝛼−1(−u𝛼)du, let y = u𝛼 , so that u = y1/𝛼 hence dy du = 𝛼u𝛼−1 = 𝛼(y1/𝛼)𝛼−1 © 2023 the authors. page 268 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 e(xr) =𝛼kr ( 1 _ )r/\ ∫ ∞ 0 (y1/𝛼) r \ +𝛼−1exp(−y) 1 𝛼(y1/𝛼)𝛼−1 dy e(xr) = kr ( 1 _ )r/\ ∫ ∞ 0 y r 𝛼\ exp(−y)dy; using ∫ ∞ 0 ymexp(−y)dy = γ(m + 1)completes the proof. the first four raw moments can be obtained from equation (16) as follows ` ′ 1 = k ( 1 𝛼 )1/\ γ ( 1 𝛼\ + 1 ) ; ` ′ 2 = k 2 ( 1 𝛼 )2/\ γ ( 2 𝛼\ + 1 ) ; ` ′ 3 = k 3 ( 1 𝛼 )3/\ γ ( 3 𝛼\ + 1 ) ; ` ′ 4 = k 4 ( 1 𝛼 )4/\ γ ( 4 𝛼\ + 1 ) ; 2.4.5 the mean, variance, skewness, and kurtosis of wep distribution the mean is the first moment about the origin when r = 1, and is derived as e(x) = `′1 = k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) (18) the variance is obtained as variance(x) = `′2 − [` ′ 1] 2 = k2 { ( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) − (( 1 _ )1/\ γ ( 2 𝛼\ + 1 ))2 } (19) the measures of skewness and kurtosis denoted by skew and kurt respectively are obtained using the first four raw moments in sub-section 2.4.4 as follows; skew = `′3 − 3` ′ 2 ` + 2` 3 ( `′2 − ` 2)3/2 = ©­­­« k3 ( 1 _ )3/\ γ ( 3 𝛼\ + 1 ) −3k2 ( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) +2 [ k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 )]3 ª®®®¬( k2 ( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) − [ k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 )2]3/2 ) (20) kurt = `′4 − 4` ′ 3 ` + 6`2 ` 2 − 3`4 ( `′2 − ` 2)2 = ©­­­­­­« k4 ( 1 _ )4/\ γ ( 4 𝛼\ + 1 ) − 4k3 ( 1 _ )3/\ γ ( 3 𝛼\ + 1 ) k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) + 6k2 ( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) [ k ( 1 𝛼\ )1/\ γ ( 1 𝛼\ + 1 )]2 − 3 [ k ( 1 𝛼\ )1/\ γ ( 1 𝛼\ + 1 )]4 ª®®®®®®¬( k2 ( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) − [ k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 )2]3/2 ) (21) proposition 5: let x be a random variable from the wep distribution, the coefficient of variance denoted cv is given by cv = √√{( 1 _ )2/\ γ ( 2 𝛼\ + 1 ) − (( 1 _ )1/\ γ ( 2 𝛼\ + 1 ))2} ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) (22) proof the coefficient of variance is defined as cv = 2 √ variance e(x) by using equations (18) and (19), the result is obtained. 2.4.6 moment generating function of wep distribution theorem 2: let x be a weibull exponential pareto random variable with probability density function g(x), the moment generating function of x denoted mx (t) is given by ∞∑︁ i=0 ti i! ki ( 1 _ )i/\ γ ( i 𝛼\ + 1 ) (23) proof: the moment generating function for a continuous random variable is defined alzaatreh et al. (2013a) as; mx(t) = e(etx) = ∫ ∞ 0 etxg(x)dx ∫ ∞ 0 etx 𝛼_ \ k ( x k )\−1 { _ ( x k )\ }𝛼−1 exp ( − { _ ( x k )\ }𝛼 ) dx etx = ∞∑︁ i=0 ( 1 + tixi i! ) = ∞∑︁ i=0 tixi i! © 2023 the authors. page 269 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 e(etx) == ∞∑︁ i=0 ti i! e(xi) by substituting e(xi) in equation (16), we shall obtain mx(t) = ∞∑︁ i=0 ti i! e(xi) = ∞∑︁ i=0 ti i! ki ( 1 _ )i/\ γ ( i 𝛼\ + 1 ) 2.4.7 relationship between wep and the weibull-pareto (wpd) distribution the relationship between the wep and wpd is established as follows: theorem 3: let y be a random variable that follows the weibull-pareto distribution with parameter (𝛼,_ ,k) defined and studied by (alzaatreh et al., 2013b) , then the random variable x=k(log ( y k ) ) 1/\ follows the wep distribution with parameters (𝛼,_ ,\,k). proof: given thaty follows the weibull-pareto distribution, then y∼(𝛼,_ ,k), required to show that x∼(𝛼,_ ,\,k). the cdf is given by alzaatreh et al. (2013b) as 1 − exp ( − { _ log ( y k )}𝛼 ) (24) required to show that x∼(𝛼,_ ,\,k), x = k ( log ( y k ))1/\ by transformation of variable, (log(yk ))=( x k ) \ , this implies that (yk ) = e ( xk ) \ and the random variable y = ke( x k ) \ by substituting y into equation (24), the cdf of wep distribution in equation (9) is obtained. 2.4.8 shannon entropy of weibull exponential pareto distribution shannon (2001) defined entropy as the measure of the level of variation of uncertainty associated with a random variable. if a random variable t follows the weibull distribution with parameters c and 𝛾, the shannon entropy for the weibull distribution by song (2001) is given by [t = 𝜗 ( 1 − 1 c ) − log ( c 𝛾 ) + 1 (25) the shannon entropy for the weibull-x family of distribution by alzaatreh et al. (2013b) is given by [x = −{logf (f−1(1 − e−t))} − 𝛾γ ( 1 + 1 c ) + 𝜗 ( 1 − 1 c ) − log ( c 𝛾 ) + 1 (26) where 𝜗 the euler’s constant in both equations. the mean of weibull distribution for the random variable t is `t = 𝛾γ ( 1 + 1 c ) (27) theorem 4: let x be a random variable from the wep distribution, then the shannon entropy [xfor the wep distribution is given by k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) − γ ( 1 + 1 𝛼 ) + 𝜗 ( 1 − 1 𝛼 ) − log(𝛼) + 1 (28) proof: by definition, shannon entropy [x is the expectation of the negative logarithm of the density function g(x). the expectation of the pdf of the weibull-x family in equation (4) is given by e[−log{g(x)}] = e [ −log ( f (x) 1 − f(x) r{−log(1 − f(x))} )] e[−log{f (x)} + log(1 − f(x)) − log[r{−log(1 − f(x))}]] e[−log( f (x))] + e[log(1 − f(x))]+ e[−log[r{−log(1 − f(x))}]] by variable transformation, if t= -log (1-f(x)), then (1f(x))=e−t , [x = e[−log{g(x)}] = e[−log(x)] − e[t]+ e[−log[r(t)]] = `x − `t + [t where `x = the mean of wep distribution `t = the mean of weibull distribution [t = the shannon entropy of weibull distribution [x= the shannon entropy of the weibull-x distribution by substituting for `x which is the mean of wep in equation (18) and also the values of [t and `t in equations (19) and (27) respectively, the shannon entropy [x of the wep distribution is obtained as [x = k ( 1 _ )1/\ γ ( 1 𝛼\ + 1 ) − γ ( 1 + 1 𝛼 ) + 𝜗 ( 1 − 1 𝛼 ) − log(𝛼) + 1 © 2023 the authors. page 270 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 2.4.9 renyi entropy of weibull exponential pareto distribution the renyi entropy of a continuous random variable x with pdf g(x) is defined by rényi (1961) as the measure of uncertainty associated with x, and the renyi entropy of x is defined by ∥r(x) = 1 1 − 𝛿 log[∥(𝛿)] (29) where ∥(𝛿) = ∫ ∞ −∞ .f 𝛿 (x)dx, 𝛿 > 0 and 𝛿 ≠ 1 (30) the renyi entropy of a random variable x that follows the wep distribution is derived by substituting the pdf of wep into equation (30) ∥(𝛿) = ∫ ∞ ∞ ( 𝛼_ \ k )𝛿 ( x k )𝛿(\−1) { _ ( x k )\ }𝛿(𝛼−1) exp ( − { 𝛿_ ( x k )\ }𝛼 ) dx let u = 𝛿_ ( x k )\ and obtain x = k ( u 𝛿_ )1/\ du dx = 𝛿_ \ k ( x k )\−1 du = 𝛿_ \ k ( x k )\−1 dx ∥(𝛿) = ∫ 0 ∞ x\𝛿𝛼−𝛿 (𝛼_ \)𝛿 _ 𝛿𝛼−𝛿 ( 1k ) \𝛿𝛼 exp(−u𝛼) 𝛿_ \ k ( 1 k ) \−1 ( k( u 𝛿_ )1/\ )\−1du = ∫ 0 ∞ ( 1 _ )− 𝛿 \ + 1 \ (u 𝛿 )𝛿𝛼− 𝛿 \ + 1 \ 𝛼 𝛿 ( \ k )𝛿−1 exp(−u𝛼)(u)−1du let y = u𝛼 , dy du = 𝛼u𝛼−1 = 𝛼(y1/𝛼)𝛼−1 ∥(𝛿) = ∫ 0 ∞ ( 1 _ )− 𝛿 \ + 1 \ ( y1/_ 𝛿 )𝛿𝛼− 𝛿 \ + 1 \ 𝛼 𝛿 ( \ k )𝛿−1 exp(−y)(y1/𝛼)−1 𝛼(y1/𝛼)𝛼−1 dy = ∫ 0 ∞ (_) 1−𝛿 \ ( 1 𝛿 )𝛿𝛼− 𝛿 \ + 1 \ ( 𝛼\ k )𝛿−1 exp(−y)y𝛿− 𝛿 𝛼𝛿 + 1 𝛼\ −1dy ∥(𝛿) = (_) 1−𝛿 \ ( 1 𝛿 ) 𝛿𝛼\−𝛿+1 \ ( 𝛼\ k )𝛿−1 γ ( 𝛿𝛼\ − 𝛿 + 1 𝛼\ ) (31) substitute the quantity in equation (31) into equation (29) to get the desired result given by ∥r(x) = 1 1 − 𝛿 log[∥(𝛿)] = 1 1 − 𝛿 log [ (_) 1−𝛿 \ ( 1 𝛿 ) 𝛿𝛼\−𝛿+1 \ ( 𝛼\ k )𝛿−1 γ ( 𝛿𝛼\ − 𝛿 + 1 𝛼\ )] 2.4.10 distribution of the order statistics of wep distribution let x1,x2,. . . ,xn be a random sample of size n from the wep distribution with the cdf and pdf given as g(x) and g(x) respectively, if x(1) , x(2) ,....,x(n) is the order statistics of the random sample, the pdf of the rth order statistics defined by david and nagaraja (2003) is given by f xr:n(x) = n (r − 1)(n − r)! g(x)r−1(1 −g(x))n−rg′(x) (32) substitute the cdf and pdf of the weibull exponential pareto distribution defined in equations (9) and (10) into equation (32) to get f xr;n(x) =  n (r−1) (n−r)! [ 1 − exp ( − { _ ( x k )\ }𝛼 )]r−1[ exp ( − { _ ( x k )\ }𝛼 )]n−r+1 x 𝛼_ \k ( x k )\−1 { _ ( x k )\ }𝛼−1 (33) the first-order statistics is obtained from equation (33) when r=1 and is given by f x1:n(x) = [ exp ( − { _ ( x k )\ }𝛼 )]n n𝛼_ \ k ( x k )\−1 { _ ( x k )\ }𝛼−1 (34) the maximum order statistics is derived from equation (33) when r=n and is given by f xn;n(x) =  [ 1 − exp ( − { _ ( x k )\ }𝛼 )]n−1[ exp ( − { _ ( x k )\ }𝛼 )] x n𝛼_ \k ( x k )\−1 { _ ( x k )\ }𝛼−1 (35) © 2023 the authors. page 271 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 2.4.11 moments, mean, and variance of order statistics of wep distribution the moment of order statistics including the mean and variance of order statistics are derived here theorem 5: let x1:n, x2:n, . . . , xn:n be the order statistics of the random sample from the wep distribution of the density function fxr;n(x), derived in equation (33), then the sth moment of the rth order statistics is given by ` s r.n =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) ks ( 1 _ )s/\ x ( 1 m ) ( s 𝛼\ +1) γ ( s 𝛼\ + 1 ) (36) proof: the sth moment of x(r:n) is defined as e(xsr:n) = ∫ ∞ −∞ xs f xr;n(x)dx (37) equation (33) can be expressed by series expansion as  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) 𝛼_ \ k ( x k )\−1 x { _ ( x k )\ }𝛼−1 exp ( − { m_ ( x k )\ }𝛼 ) (38) where m=n-r+i+1, and cr:n = n (r−1)!(n−r)! substitute equation (38) into (37) to obtain  cr:n ∑r−1 i=0 (−1) i ( r − 1 i ) ∫ ∞ 0 xs 𝛼_ \k ( x k )\−1 x { _ ( x k )\ }𝛼−1 exp ( − { m_ ( x k )\ }𝛼 ) dx (39) by following the steps in subsection 2.4.4, theorem 1, the solution to the integral in equation (39) is obtained as ks ( 1 _ )s/\ ( 1 m )( s𝛼\ +1) γ ( s 𝛼\ + 1 ) (40) and the sth moment of the rth order statistics of wep distribution is given by cr:n r−1∑︁ i=0 (−1)i ( r − 1 i ) ks ( 1 _ )s/\ ( 1 m )( s𝛼\ +1) γ ( s 𝛼\ + 1 ) corollary 1: the mean of order statistics of the wep distribution is obtained as `r;nwep =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) k ( 1 _ )1/\ x ( 1 m )( 1𝛼\ +1) γ ( 1 𝛼\ + 1 ) (41) corollary 2: let 𝜎sr:n(wep) denote the variance of order statistics of the wep distribution, then the explicit expression for the variance is given by 𝜎 s r:nwep =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) k2( 1 _ )2/\ ( 1 m )( 2𝛼\ +1) γ ( 2 𝛼\ + 1 ) − [ n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) k( 1 _ )1/\ ( 1 m )( 1𝛼\ +1) γ ( 1 𝛼\ + 1 )]2 (42) proof: the variance is proved using the relation; 𝜎 s r:nwep = ` 2 r:n − ( `r:nwep) 2 using equation (36), `2r:n is obtained as ` 2 r:n = n (r − 1)!(n − r)! r−1∑︁ i=0 (−1)i ( r − 1 i ) k2 ( 1 _ )2/\ ( 1 m )( 2𝛼\ +1) γ ( 2 𝛼\ + 1 ) using equation (41), (`r;nwep ) 2 is obtained as ( `r:nwep)2 = [ n (r − 1)!(n − r)! r−1∑︁ i=0 (−1)i ( r − 1 i ) k ( 1 _ )1/\ ( 1 m )( 1𝛼\ +1) γ ( 1 𝛼\ + 1 )]2 3. results and discussion 3.1 generalizationofpropertiesoforderstatistics forsome lifetime distribution the mean, variance, skewness, kurtosis, and some other important statistical properties can be derived for some lifetime distributions using the theory and application of order statistics. this sub-section generalized some few properties of order statistics for some lifetime distribution as follows: © 2023 the authors. page 272 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 3.1.1 exponentialparetodistribution(alkadimandboshi, 2013) corollary 3: if 𝛼=1, in equation (36) the result for sth moment of the rth order statistics of the ep distribution is given by ` s r:nep =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) ks ( 1 _ )s/\ x ( 1 m )( s\ +1) γ ( s \ + 1 ) (43) the mean of order statistics of ep distribution is derived and given by `r:nep =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) k ( 1 _ )1/\ x ( 1 m )( 1\ +1) γ ( 1 \ + 1 ) (44) the mean of the minimum x(1:n) order statistics of ep distribution is given by `1:nep = nk ( 1 _ )1/\ γ ( 1 \ + 1 ) (45) the mean of the maximum x(n:n) order statistics of ep distribution is given by `n:nep = n−1∑︁ i=0 (−1)i ( n − 1 i ) nk ( 1 _ )1/\ ( 1 i + 1 )( 1\ +1) γ ( 1 \ + 1 ) (46) corollary 4: if r=n=1 and 𝛼=1, the result for a central moment about the origin and the mean for the ep distribution al kadim and boshi (2013) is obtained from this study as ` ′ s = k s ( 1 _ )s/\ γ ( s \ + 1 ) (47) the mean of a random variable x from the ep distribution is e(x) = k ( 1 _ )1/\ γ ( 1 \ + 1 ) (48) 3.1.2 weibull-rayleigh distribution (ahmad et al., 2017) corollary 5. if \=2 and _ = 12𝛽 , in equation (36) the s th moment of the rth order statistics of the wr distribution is given by ` s r:nwr =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) ks x(2𝛽)s/2 ( 1 m )( s2𝛼 +1) γ ( s 2𝛼 + 1 ) (49) the mean of order statistics of wr distribution is derived and given by `r:nwr =  n (r−1)!(n−r)! ∑r−1 i=0 (−1) i ( r − 1 i ) k x(2𝛽)1/2 ( 1 m )( 12𝛼 +1) γ ( 1 2𝛼 + 1 ) (50) the mean of the minimum x(1:n) order statistics of wr distribution is given by `1:nwr = nk(2𝛽)1/2γ ( 1 2𝛼 + 1 ) (51) the mean of the maximum x(n:n) order statistics of wr distribution is given by `n:nwr =  ∑n−1 i=0 (−1) i ( n − 1 i ) nk(2𝛽)1/2 x ( 1 i+1 )( 12𝛼 +1) γ ( 1 2𝛼 + 1 ) (52) corollary 6. the sth moment of the wr distribution developed by ahmad et al. (2017) is given by ` ′ s = (2𝛽) s/2ksγ ( s 2𝛼 + 1 ) (53) proof: if r=n=1 and \=2 and _ =1/2 𝛽 in equation (36) the desired result is obtained the mean of a random variable x from the wr distribution is e(x) = (2𝛽)1/2kγ ( 1 2𝛼 + 1 ) (54) remark: similar results can be deduced for the rayleighrayleigh distribution developed by ateeq et al. (2019) and for other models presented in table 1. 3.2 parameter estimation and simulation this section is for determining the estimates of parameters of wep distribution using the method of maximum likelihood estimation (mle). a simulation study is also conducted to assess the performance of the procedure. © 2023 the authors. page 273 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 3.2.1 maximum likelihood estimation let x1, x2,..., xn,be independent and identically distributed random sample of size n from the wep distribution with pdf derived as g(x) in equation (9) with a set of parameters 𝜑=(𝛼,\,_ ,k). the likelihood function of the distribution is obtained as; lik[g(x, 𝜑)] = n∏ i=1 [ n𝛼_ \ k ( x k ) (\−1) { _ ( x k )\ }(𝛼−1) exp ( − { _ ( x k )\ }𝛼 )] (55) the log-likelihood function loglik[g(x,𝜙)] denoted as ll is ll =  nlog𝛼 + nlog_ + nlog\ − nlogk+ (\ − 1) ∑ logx − n(\ − 1)logk +n(𝛼 − 1)log_ − n(𝛼 − 1)logk\ +(𝛼 − 1) ∑ logx\ − ∑ { _ ( x k )\ }𝛼 (56) the normal equations are obtained as derivatives of ll for the parameters 0 = dll d𝛼 =  n 𝛼 + nlog_ − nlogk\ + ∑ logx\ − ∑ { _ ( x k )\ }𝛼 log ( _ ( x k )\ ) (57) 0 = dll d_ = n _ + n𝛼 _ + 𝛼 _ ∑︁ { _ ( x k )\ }𝛼 (58) 0 = dll dk =  −nk − n(\−1) k + n(𝛼−1) k + 𝛼\k ∑ { _ ( x k )\ }𝛼 (59) 0 = dll d\ =  n \ + ∑ logx − nlogk − n(𝛼 − 1) \k +(𝛼 − 1) ∑ \ x − 𝛼 ∑ { _ ( x k )\ }𝛼 log ( x k ) (60) a numerical solution to the above equations is adopted for the estimates of the parameters which are easier using the statistical software. 3.2.2 simulation study assessment of the estimation of parameter procedure is performed by conducting a simulation study using the r-statistical software as follows; 1. simulated data are generated using equation (14) given by x = k { 1 _ [ −log(1 − u) 1 𝛼 ]} 1\ 2. the sample sizes taken are n = 20, 50, 250, 350, 500 3. two sets i and ii of parameter values are defined as i = (𝛼=0.5, \=1, _ =2.5, k=1.5) and ii = (𝛼=1.0, \=2, _ =3.5, k=2.0) 4. replicate the process for each sample size n=10,000 number of times 5. compute the mse by using mse ∅ = 1n ∑n i=1 (∅i’∅) 2 where ∅’irepresents wep parameters 6. step five is carried our repeatedly for each parameter. the estimated values are obtained for the bias, mean square error (mse), root mean square error (rmse), and standard errors. the simulation study shows that the parameters of the distribution are stable in addition; the consistency of the mse values for the maximum likelihood estimations implies that the estimation procedure is adequate. the results revealed that the mse and rsme decrease as the sample size increases for both sets of actual values of the parameter. the standard errors also converge to zero as the sample size increases. the results from the simulation studies are presented in table 2 for the first set of parameters and table 3 for the second set of parameters. 3.3 application to lifetime datasets the usefulness of the distribution is demonstrated by analyzing three real-life datasets using the r software (core team, 2013) . the best-fitted model is usually identified with the smallest values of goodness-of-fit criteria which are the log-likelihood (ll), akaike information criterion (aic), bayesian information criterion (bic), consistent akaike information criterion (caic), hannan-quinn information criterion (hqic), the kolmogorov statistics and p-value. the criteria are defined as follows; aic=-2ll+2c; bic=-2ll+clog(n); caic=-2ll+ 2c(n−2)n−c−2 ; hqic = 2log (log(n)(c − 2ll)). the performance of the wep distribution is compared with some similar families of distributions and some notable models existing in the literature with the density functions defined by 1. generalized exponential weibull (gew) distribution gew (x; 𝛼, 𝛽 , \ , k) = \(𝛼 + 𝛽kx(k−1)) exp(−(𝛼x + 𝛽xk))(1 − exp(𝛼x + 𝛽xk))\−1 2. transmuted new weibull pareto (tnwp) distribution tnwp(x;_ , 𝛽 , \ , k) = 𝛽 \ k ( x k ) ( 𝛽 −1) e(−\( x k ) 𝛽 ( 1 − _ + 2_e−\( x k ) 𝛽 ) © 2023 the authors. page 274 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 3. kumaraswamy exponential pareto (kep) distribution kep(x; 𝛼, 𝛽 , \ , k) = 𝛼 𝛽_ \ k ( x k ) (\−1) e−_ ( x k ) \ ( 1 − e−_ ( x k ) \ )𝛼−1 ( 1 − ( 1 − e−_ ( x k ) \ )𝛼 ) 𝛽 −1 4. gompertz exponential pareto (gep) distribution gep(x; 𝛼, _ , 𝛽 , \ , k) = 𝛼_ \ k ( x k ) (\−1) ( e−_ ( x k ) \ )− 𝛽 e 𝛼 𝛽 [ 1− ( e −_ ( xk ) \ )− 𝛽 ] 5. beta exponential pareto (bep) distribution bep(x; 𝛼, _ , 𝛽 , \ , k) = 𝛼\ _b(𝛼 𝛽) ( x _ ) (\−1) e−𝛼 𝛽 ( x _ ) \ [ 1 − e− 𝛽 ( x _ ) \ ]𝛼−1 3.3.1 application to the hydrological data set the first data contain 72 exceedances of flood peaks (inm3/s) of the wheaton river discharge near carcross in yukon territory, canada for the years 1958-1984. the data set has been applied by several authors including aryal (2019) using bep, tahir and akhter (2018) using tnwp, and recently by adeyemi et al. (2021) for evaluating the performance of the gep distribution. figure 3. plots of pdfs and cdfs of fitted distributions fitted to the hydrological data first data set: 1.7, 2.2, 14.4, 1.1, 0.4, 20.6, 5.3, 0.7, 1.4, 18.7, 8.5, 25.5, 11.6, 14.1, 22.1, 1.1, 0.6, 2.2, 39.0, 0.3, 15.0, 11.0, 7.3, 22.9, 0.9, 1.7, 7.0, 20.1, 0.4, 2.8, 14.1, 9.9, 5.6, 30.8, 13.3, 4.2, 25.5, 3.4, 11.9, 21.5, 1.5, 2.5, 27.4, 1.0, 27.1, 20.2, 16.8, 5.3, 1.9, 10.4, 13.0, 10.7, 12.0, 30.0, 9.3, 3.6, 2.5, 27.6, 14.4, 36.4, 1.7, 2.7, 37.6, 64.0, 1.7, 9.7, 0.1, 27.5, 1.1, 2.5, 0.6, 27.0. the values of the estimated parameters of the competing models and the goodness-of-fit criteria are displayed in table 4 and table 5 respectively. the visual result of goodness-of-fit from data analysis in form of the histogram with the estimated densities and the cdfs of the fitted models are displayed in figure 3. table 4 revealed that the wep distribution competes favorably with the gep model and performs better than tnwp, kep, and bep distributions based on the smallest values of goodness-of-fit statistics. figure 3 supported the selection of the proposed model as more flexible than the other models for the dataset. 3.3.2 application to tensile strength of polyester fibers the second data represents 30 measurements of the tensile strength of polyester fibers available in (quesenberry and hales, 1980) . figure 4. plots of histogram with densities and cdfs of fitted distributions to the tensile strength data second data set: 0.023, 0.032, 0.054, 0.069, 0.081, 0.094, 0.105, 0.127, 0.148, 0.169, 0.188,0.216, 0.255, 0.277, 0.311, 0.361, 0.376, 0.395, 0.432, 0.463, 0.481, 0.519,0.529, 0.567, 0.642, 0.674, 0.752, 0.823, 0.887, 0.926 the computed results of estimated parameters and the goodness-of-fit criteria are displayed in table 6 and table 7 respectively for the models under consideration. figure 4 is the pictorial display of goodness-of-fit from data analysis in form of the histogram with the estimated densities and cdfs of the fitted models to the tensile strength data set. the fit of the wep model is compared with tnwp, gep, gew, and kep models. results displayed in table 6 revealed that the wep model has more flexible capabilities for the data than the competitors. the visual results from the estimated densities and cdfs in figure 4 strengthened the choice of the wep model. 3.3.3 application to lifetimes of steel specimens the data represents the lifetimes (t) of steel specimens tested at stress (s) level of s=38.5 obtained from the 14 different stress levels reported in (lawless, 2011) . third data set: 60, 51, 83, 140, 109, 106, 119, 76, 68, 67, 111, 57, 69, 75, 122, 128, 95, 87, 82, 132. the lifetime data is fitted to the wep model and compared with gep, gew, and kep models. computed results of estimated parameters and the goodness-of-fit criteria are presented in table 8 and table 9 respectively. the plots for the densities and cdfs are displayed in figure 5. application of the proposed models to the data set © 2023 the authors. page 275 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 figure 5. plots of pdfs and cdfs of fitted distributions to the steel specimens data of steel specimens revealed the suitability of the wep model as a better lifetime distribution for fitting the data compared to some other existing distributions in the literature. the wep model provides the smallest aic, caic, and bic and the plots in figure 5 substantiate our choice of wep distribution. 4. conclusion the wep model is a new lifetime distribution with adequate potential for analyzing left-skewed, right-skewed, and approximately symmetric phenomena from the field of hydrology, reliability engineering, actuarial and finance, and public health. it is also suitable for fitting real-life datasets in other areas of applications characterized by risky kurtosis. it is confirmed in this study that wep has superior performance than the competing distributions for modeling the reliability and the hydrological data sets and the lifetime of steel specimens. the discoveries from the theory of order statistics extended in the study established a novel area of study in distribution theory which also contributed to the conclusion that the wep distribution provides sufficient characterizations for wr, ep, rr distributions, and some other existing lifetime distributions. other important areas of further research include the estimation of parameters by order statistics and the real-life application of moments of order statistics in predictive modeling. 5. acknowledgment the authors are grateful for the contributions and suggestions of the editors, the editor-in-chief and all the anonymous reviewers which improve the original manuscript. special thanks to mr. john anih for the payment of the apc on behalf of the corresponding author. references adeyemi, a. o., e. e. akarawak, and i. a. adeleke (2021). the gompertz exponential pareto distribution with the properties and applications to bladder cancer and hydrological datasets. communications in science and technology, 6(2); 107–116 ahmad, a., s. ahmad, and a. ahmed (2017). characterization and estimation of weibull-rayleigh distribution with applications to life time data. applied mathematics and information sciences letters, 5; 71–79 akarawak, e. e., i. a. adeleke, and r. o. okafor (2013). the weibull-rayleigh distribution and its properties. journal of engineering research, 18(1); 56–67 akarawak, e. e., i. a. adeleke, and r. o. okafor (2017). maximum likelihood estimation and applications of the weibull-rayleigh distribution. international journal of mathematical sciences and optimization: theory and applications, 2017; 233–249 al kadim, k. a. and m. a. boshi (2013). exponential pareto distribution. mathematical theory and modeling, 3(5); 135– 146 aljuhani, w., h. s. klakattawi, and l. a. baharith (2022). alpha power exponentiated new weibull-pareto distribution: its properties and applications. pakistan journal of statistics and operation research; 703–720 alzaatreh, a., f. famoye, and c. lee (2013a). weibull-pareto distribution and its applications. communications instatisticstheory and methods, 42(9); 1673–1691 alzaatreh, a. and i. ghosh (2015). on the weibull x family of distributions. journal of statistical theory and applications, 14(2); 169–183 alzaatreh, a., c. lee, and f. famoye (2013b). a new method for generating families of continuous distributions. metron, 71(1); 63–79 aryal (2019). on the beta exponential pareto distribution. statistics, optimization and information computing, 7(2); 417– 438 ateeq, k., t. b. qasim, and a. r. alvi (2019). an extension of rayleigh distribution and applications. cogent mathematics & statistics, 6(1); 1622191 core team, r. (2013). r: a language and environment for statistical computing. vienna, austria david, h. a. and h. n. nagaraja (2003). order statistics. john wiley and sons dikko, h. and a. faisal (2017). a new generalized exponential-weibull distribution; its properties and application. bayero journal of pure and applied sciences, 10(2); 29–37 elbatal, i. and g. aryal (2017). a new generalization of the exponential pareto distribution. journal of information and optimization sciences, 38(5); 675–697 hassan, a. s., r. e. mohamed, o. kharazmi, and h. f. nagy (2022). a new four parameter extended exponential distribution with statistical properties and applications. pakistan journal of statistics and operation research, 18(1); 179–193 lawless, j. f. (2011). statistical models and methods for lifetime data. john wiley & sons lee, c., f. famoye, and o. olumolade (2007). beta-weibull distribution: some properties and applications to censored data. journal of modern applied statistical methods, 6(1); 17 luguterah, a. and s. nasiru (2015). transmuted exponential © 2023 the authors. page 276 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 table 2. simulation study for set of parameters i=(𝛼=0.5,\=1,_ =2.5,k=1.5) bias mse n â _̂ \̂ k̂ â _̂ \̂ k̂ 20 0.6987 -1.2998 0.1999 -0.2995 0.8459 2.0494 0.3998 0.4515 50 0.6990 -1.3005 0.2006 -0.3007 0.6336 1.8353 0.1832 0.2352 250 0.6987 -1.3006 0.2003 -0.2991 0.5183 1.7200 0.0691 0.1185 500 0.7000 -1.3001 0.2001 -0.2989 0.5044 1.7048 0.0544 0.1042 1000 0.6986 -1.3000 0.1998 -0.2992 0.4973 1.6972 0.0471 0.0972 rmse st.error n â _̂ \̂ k̂ â _̂ \̂ k̂ 20 0.9198 1.4316 0.6323 0.6719 0.5981 0.5999 0.5998 0.6015 50 0.7960 1.3547 0.4208 0.4849 0.3793 0.3795 0.3781 0.3804 250 0.7199 1.3115 0.2628 0.3442 0.1695 0.1688 0.1701 0.1704 500 0.7102 1.3057 0.2334 0.3228 0.1199 0.1202 0.1199 0.1196 1000 0.7052 1.3028 0.2171 0.3117 0.0848 0.0846 0.0848 0.0851 table 3. simulation study for set of parameters ii=(𝛼=1.0,\=2,_ = 3.5,k=2.0) bias mse n â _̂ \̂ k̂ â _̂ \̂ k̂ 20 -0.0523 -2.5528 -1.0522 -1.0528 0.0150 6.5292 1.1193 1.1208 50 -0.0526 -2.5526 -1.0525 -1.0527 0.0077 6.5207 1.1126 1.1130 250 -0.0526 -2.5526 -1.0527 -1.0525 0.0038 6.5168 1.1092 1.1088 500 -0.0526 -2.5526 -1.0526 -1.0524 0.0032 6.5161 1.1086 1.1082 1000 -0.0526 -2.5526 -1.0525 -1.0523 0.0030 6.5160 1.1080 1.1081 rmse st.error n â _̂ \̂ k̂ â _̂ \̂ k̂ 20 0.1225 2.5552 1.0579 1.0587 0.1108 0.1109 0.1107 0.1111 50 0.0875 2.5535 1.0548 1.0549 0.0699 0.0701 0.0701 0.0702 250 0.0612 2.5528 1.0532 1.0530 0.0314 0.0314 0.0313 0.0313 500 0.0571 2.5526 1.0528 1.0526 0.0221 0.0222 0.0221 0.0220 1000 0.0549 2.5526 1.0526 1.0526 0.0156 0.0157 0.0156 0.0156 table 4. log-likelihood and maximum likelihood estimates of the parameters for the flood peaks data model â 𝛽 _̂ \ k̂ -ll gep 0.6735 0.2594 0.3099 0.7474 0.8814 499.7330 wep 0.0786 3.1539 11.1779 10.1814 501.1056 tnwp 0.4514 0.4092 6.7312 0.8771 502.9130 kep 0.9245 0.2594 0.3099 0.7624 0.8814 501.1506 bep 0.0332 0.4984 0.7474 0.2985 0.5482 501.9790 table 5. goodness-of-fit statistics for the flood peaks data model aic caic bic hqic k-s p-value wep 509.1056 509.7026 518.2122 512.7310 0.1067 0.3850 gep 509.7330 510.6461 521.1164 514.2648 0.1029 0.4310 tnwp 510.9130 511.5100 520.0197 514.5384 0.1069 0.3812 kep 511.1506 512.0589 522.5340 515.6824 0.1071 0.3802 bep 511.9590 512,8680 523.3420 516.4910 © 2023 the authors. page 277 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 table 6. log-likelihood and estimated parameters for the tensile strength data model â 𝛽 _̂ \ k̂ -ll wep 0.0402 2.4076 32.9847 0.3891 -1.7503 tnwp 6.5409 0.2768 1.7556 1.3982 -1.7377 gep 15.9217 30.1267 0.3245 0.9161 4.9943 -2.3263 gew 3.1808 2.9046 21.1988 0.1269 -1.2846 kep 0.1795 13.5155 11.7830 7.4832 4.1216 -2.2521 table 7. goodness-of-fit statistics for the tensile strength data model aic caic bic hqic k-s p-value wep 4.4993 6.0993 10.1041 6.2923 0.0826 0.9760 tnwp 4.5246 6.1246 10.1294 6.3176 0.0853 0.9679 gep 5.3473 7.8473 12.3533 7.5886 0.0859 0.9661 gew 5.4308 7.0308 11.0357 7.2238 0.0884 0.9568 kep 5.4959 7.9959 12.5018 7.7371 0.0917 0.9427 table 8. log-likelihood and estimated parameters for the steel specimen data model â 𝛽 _̂ \ k̂ -ll wep 1.9542 33.5981 1.409 9.6908 102.9148 gep 0.0065 0.7775 0.5749 5.6195 1.1537 102.9122 gew 0.0232 1.0449 10.9496 -0.1876 104.4920 kep 9.1038 3.5236 0.1109 0.6503 1.4219 105.6481 table 9. goodness-of-fit statistics for the steel specimen data model aic caic bic hqic k-s p-value wep 213.8297 216.4964 217.8126 214.6072 0.1057 0.9615 gep 214.8244 219.8031 219.8031 215.7963 0.1096 0.9485 gew 214.8244 219.6506 220.9669 217.7615 0.1387 0.7871 kep 221.2962 225.5819 226.2748 222.2680 0.1405 0.7744 © 2023 the authors. page 278 of 279 adeyemi et. al. science and technology indonesia, 8 (2023) 265-279 pareto distribution. far east journal of theoretical statistics, 50(1); 31–49 nasiru, s. and a. luguterah (2015). the new weibull-pareto distribution. pakistan journal of statistics and operation research, 11(1); 103–114 quesenberry, c. p. and c. hales (1980). concentration bands for uniformity plots. journal of statistical computation and simulation, 11(1); 41–53 rashwan, n. i. and m. m. kamel (2020). the beta exponential pareto distribution. far east journal of theoretical statistics, 58; 91–113 rayleigh, l. (1896). the theory of sound, volume 2. macmillan rényi, a. (1961). on measures of entropy and information. the university of california press, 4; 547–562 shannon, c. e. (2001). a mathematical theory of communication. the bell system technical journal, 5(1); 3–55 song, k. (2001). renyi information: log-likelihood and intrinsic distribution measure. journal of statistical planning and inference, 93; 51–69 tahir, a. and a. s. akhter (2018). transmuted new weibullpareto distribution and its applications. applications and applied mathematics: an international journal (aam), 13(1); 3 tuoyo, d. o., f. c. opone, and n. ekhosuehi (2021). the topp-leone weibull distribution: its properties and application. earthline journal of mathematical sciences, 7(2); 381–401 weibull, w. (1951). a statistical distribution function of wide applicability. journal of applied mechanics, 18; 293– 297 © 2023 the authors. page 279 of 279 introduction experimental section materials and method the new extension of exponential pareto distribution sub-models of wep distribution properties of the weibull exponential pareto distribution the reliability and the hazard rate function asymptotic behavior of wep quantile function, simulation, and median moments of wep distribution the mean, variance, skewness, and kurtosis of wep distribution moment generating function of wep distribution relationship between wep and the weibull-pareto (wpd) distribution shannon entropy of weibull exponential pareto distribution renyi entropy of weibull exponential pareto distribution distribution of the order statistics of wep distribution moments, mean, and variance of order statistics of wep distribution results and discussion generalization of properties of order statistics for some lifetime distribution exponential pareto distribution 5 weibull-rayleigh distribution 2 parameter estimation and simulation maximum likelihood estimation simulation study application to lifetime datasets application to the hydrological data set application to tensile strength of polyester fibers application to lifetimes of steel specimens conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper the enhancement solubility and stability of erythromycin formatted in solid lipid nanoparticles by utilizing pva as stabilizer mardiyanto1*, budi untari1, najma anuria fithri1, ady mara2, andre agung aprianto1, gustina emilia ningsih1 1pharmaceutical department, faculty of mathematics and natural science, sriwijaya university, palembang, 30662, indonesia2department of chemistry, faculty of mathematics and natural science, sriwijaya university, palembang, 30662, indonesia *corresponding author: mardiyanto@mipa.unsri.ac.id abstractinfectious diseases have changed the world order today where the infection is the main cause of illness and death in the world.erythromycin is a macrolide antibiotic that can generally inhibit the growth of staphylococcus aureus and resistant strains. the freemolecule of erythromycin in the part of the body does not reach staphylococcus aureus because it is degraded by the first-pass effect.nanoparticles can minimize damage to active substances due to first-pass effects because the particles have been protected bybiopolymers leading to the minimizing damage of active substances. formulation of nanoparticles loading erythromycin was usedwith the following variations in the amount of erythromycin 25 to 100 mg. erythromycin was formulated by the coated polymerto changes the physics of the erythromycin into a particle. preparation of erythromycin into nanoparticles was utilized stearicacid polymer, peg-400, and polyvinyl alcohol using hot homogenization and ultrasonication method. results showed that theoptimum formula was the second formula (f2) with a percentage of encapsulation efficiency of 80.89773±0.11364. the results ofthe characterization of submicron particle formation such as morphology, diameter (particle size) and distribution (pdi) of f2 werespherical 518.6 nm; 0.096 pdi; and a zeta potential value of -12 mv respectively. the particles loading erythromycin were successfullyincreasing the stability of erythromycin for up to 5 cycles in terms of the heating-cooling-cycles test and also the solubility in sif. keywordslipid-nanoparticles, pva, stearic-acid, erythromycin, stability, solubility received: 28 december 2021, accepted: 10 march 2022 https://doi.org/10.26554/sti.2022.7.2.195-201 1. introduction bacterial infection is a disease caused by the presence of pathogenic bacteria (chen et al., 2021; can et al., 2015; maglangit et al., 2021). before this pandemic period, infectious diseases were the main cause of high morbidity and mortality in developing countries but now it is occurring in all countries. as the impact is the increasing use of anti-infective drugs (vabre et al., 2020; wong et al., 2020; blumenberg et al., 2020). erythromycin belongs to the class of antibiotic drugs that inhibit the process of protein synthesis by bacteria (basu and smith, 2021; martingano et al., 2020). erythromycin base (figure 1) is unstable when it enters the gastric uid, so it is used in the form of esters or lm-coated on erythromycin base and causes a decrease in solubility. in addition, the oral therapeutic dose of erythromycin is quite large, approximately 250 to 500 mg (özbek et al., 2021; fateme et al., 2020; cao et al., 2019). previously it was known that lipid particles such as stearic acid can encapsulate drug substances that have low solubility in water (khongkaew and chaemsawang, 2021; mardiyanto et al., 2021). this type of drug substance represents more than 70% of newly discovered drug substances and they are ready to be made into medicinal preparations. lipid particles are also often chosen because when given orally, the drug that they load will be stable and do not pass through the rst-pass eect (fonseca-santos et al., 2020; landh et al., 2020; wang et al., 2021). polyvinyl alcohol (pva) is used as the stabilizer of the submicron particle formation. pva is a substance that has high tensile strength and exibility and functions as a lowering of the surface tension between the 2 phases. the polar hydroxyl group of pva will bind to water molecules, while the vinyl chain has capability to bind the non-polar molecules so that the emulsion becomes stable (qiao et al., 2022; ikeuchi-takahashi et al., 2016). solid lipid nanoparticle has been developed by using liquid lipid (mardiyanto et al., 2021) and also encapsulated antibiotic such as azithromycin to increase the solubility (bhathttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.195-201&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.195-201 mardiyanto et. al. science and technology indonesia, 7 (2022) 195-201 figure 1. molecular structure of erythromycin tacharyya and reddy, 2019) but utilizing pva as stabilizer of lipid particles loading antibiotics has not been investigated yet. based on this information, it is necessary to investigate the preparation and characterization of lipid particles loading erythromycin using pva as stabilizer. determination of the optimal formula based on the calculation of the percent encapsulation eciency (%ee). the optimum formula was then evaluated to determine the character of the resulting particle, which included the physical properties using psa followed by stability and solubility evaluation. 2. experimental section 2.1 materials theactivesubstance inananalyticalgradeofbase-erythromycin was obtained from sigma-aldrichr. the materials in synthetic grade are tween 80 (merc-kgaar) and peg 400 (merckgaar). the solvents in analytical grades are ethanol 96% (merc-kgaar), ethyl-acetate (merc-kgaar), and aquabidest (otsu-wfir). 2.2 laboratory work 2.2.1 preparation of lipid and water phase the stearic acid was weighed according to the formula and melted in a water-bath controlled temperature (memmertr) at 60◦c. furthermore, the powder of the drug ingredient erythromycin was weighed and added to the melted lipid using a magnetic stirrer (ikar c-mag). in the aqueous phase, there are tween-80 and peg-400. the weighing of tween 80 and peg-400 was adjusted relating to the f1, f2, and f3. then mixed polysorbat-80 and polyethylenglycol-400. the mixing process using stirrer at a speed of 750 rpm (60 minutes) at 60◦c. then this mixtures were stored in a container at 60◦c (rupenagunta et al., 2011; fu et al., 2014; chantaburanan et al., 2017). 2.2.2 formula the formulas used in this study were three formulas and variations were made on the amount of erythromycin. the amount of stearic acid is in the range of 1 to 2.5%. the amount of tween 80 was used in 2 to 7.5% (fonseca-santos et al., 2020; fonseca-santos et al., 2020; chantaburanan et al., 2017). the formula was represented in table 1. 2.2.3 formation of lipid particles loaded erythromycin solid lipid nanoparticles were formatted using hot homogenization and ultrasonication methods. the manufacture of nanoparticles was begun with the manufacture of the lipid phase. erythromycin was dispersed into stearic acid which has been heated over a water bath at a temperature of 75◦c. then the water-mixtures were made by adding polysorbat-80, polyethylenglycol-400, and pva and then stirred (150 rpm) for 3 hours at a temperature of 75◦c. the lipid phase was then dispersed into the aqueous phase by drop by drop on a magnetic stirrer for 3 minutes to form an oil-in-water emulsion, and then further sonicated using an elmasonicr s180h (bath sonicator) for 5 minutes, with an amplitude of 35% to form a nanoparticles. the hot nano-emulsion was quickly poured into 100 ml of cold wfi to obtain nanoparticles. control slns were prepared in the same way without adding erythromycin (bhattacharyya and reddy, 2019; fonseca-santos et al., 2020). 2.2.4 purication and determination of indirect encapsulation a10 mlparticles sample was centrifuged at 12,000 rpm for30 minutes using hettichr eba-bs centrifuge to obtain 2 phases, namely the adsorbed phase and the non-adsorbed phase. perform non-absorbed phase separation, then add wfi ad 10 ml into the adsorbed phase, and centrifugation was carried out again. this treatment was carried out three times to obtain a solution of erythromycin particles with a non-adsorbed phase. determination of indirect encapsulation (%ee) was calculated by making a calibration curve using serial amount of erythromycin stock solution with a concentration of 1000 ppm. measurements using uv-1700 shimadzur were adjusted for _ 207 nm. the a results of each measurement are used in the linear regression (y = a + bx) to determine the amount erythromycin as indirect-method. 2.2.5 measurement of product acidity measurement of product acidity was conducted by entering the probe of instrument (luthron ph electroder) into the lipid particles loading erythromycin dispersion of f1, f2, and f3 simulant after preparation. after that, the results of ph were evaluated by looking at the input listed on the ph meter screen. measurements were carried out three times (mardiyanto et al., 2021). 2.2.6 characterization of physical properties of particles method applied to recognize and evaluate the size of particles, distribution and zeta-potential was psa sz-nano by horibar. determination of the mean diameter, pdi, and z using the dynamic-light-scattering. the sln sample was diluted and taken as much as 50 `l of three replication, then put into © 2022 the authors. page 196 of 201 mardiyanto et. al. science and technology indonesia, 7 (2022) 195-201 table 1. the formula of erythromycin in lipid particles amount (g) materials function f1 f2 f3 erythromycin active-substance 0.025 0.050 0.100 stearic-acid lipid 2.5 2.5 5.0 polysorbate-80 surfactant 5 5 5 coglicol-400 co-surfactant 2.5 2.5 2.5 pva stabilizer 0.2 0.2 0.2 water-for-injection solvent 100 ml 100 ml 100 ml the psa cuvette. particle diameter and z measurements were carried out with scattering of two angles (90◦ to 173◦). the visualization of sln was captured on room temperature without water using electron microscope by carl zeissr. the serial dilution was impacted to the physical sln though the dispersion of might be added the water up to 1:100 (mardiyanto et al., 2021). 2.2.7 thermodynamic and mechanic test of stability a thermodynamic test was conducted by the heating-cooling process. the evaluation was followed out by keeping the nlp preparation at the chill temperature for over-night in the refrigerator (toshibar). the suspensions were displaced into an oven at warm temperature (40◦c) overnight (1 cycle), then the test was continued for six cycles then was observed of phase changing of sln product as organoleptically also phevaluation during the cycles (almanassra et al., 2021; freitas and müller, 1999). mechanical test (centrifugation) sln samples were centrifuged at 12,000 xg for an half hour of three cycles. the procedures were the same as the step-work of the presence of sedimentation during the year of storage of the preparation. observations were made by looking at whether or not the separation occurred per 1 cycle (mardiyanto et al., 2021). 2.2.8 solubility test the purpose of the solubility test was to determine the solubility of the sln erythromycin formula compare to the baseerythromycin. the solubility test used several types of solvents in the form of distilled water, sif, sodium hydroxide, sodium bicarbonate solution, acid chloride solution, and sgf of 2 ml each tube. the testing procedure carried out refers to the research conducted by mahmood et al. (2020). parameters observed were organoleptic and physical changes of the preparation. 3. results and discussion 3.1 formation of nanoparticle loading erythromycin sln was formatted using hot homogenization method with ultrasonication technique. the sonication method is a dispersing process, which is applied for the formation of sln-dispersions. this sonication technique is based on the cavitation process. the oil phase was prepared by adding erythromycin to stearic acid which had been melted beforehand in a water bath at 75◦c. after that the water-mixtures were made by adding polysorbate-80, polyethylenglycol, and pva at the same temperature of 75◦c (ikeuchi-takahashi et al., 2016; fonsecasantos et al., 2020; chantaburanan et al., 2017; qiao et al., 2022; khongkaew and chaemsawang, 2021). the merging of the two phases was carried out by dispersing the lipid phase into the aqueous phase by slowly adding and continuing by agitation process for 3 minutes to form an oil-in-water emulsion and to get the spherical and small-pdi particles and inhibit the aggregation during preparation. the agitation process using a magnetic stirrer can also hinder the coalescence of the 2 phases. furthermore, after a mixture of the two phases (pre-emulsion) is formed, the solvent was added to aqua pro injection (wfi) up to 100 ml. the choice of wfi solvent is because wfi has a high purity compared to aquadest solvents to prevent contamination and maintain the stability of the preparation. wfi solvents are also free of pyrogens (disease-causing microorganisms). the preparation that has been formed is then homogenized using a bath-sonicator. the principle of this sonication is that the preparation does not directly come into contact with the tool, but through an intermediate medium in the form of a liquid. ultrasonic waves pass through the liquid in the bath and pass through where the sample is located and can also reduce physical barriers to increase the dispersion ability between the dispersed substance and the dispersion. sonication is also a standard procedure to prevent agglomeration of samples. duration of homogenization was impacted to diameter of sln and tiny diameter is inuencing to the constant diameter without surface interaction of grouping particles. hight-energy of sonic-waves in this method can hinder the coalescence particles and produce the dispersion by the addition of stabilizers (rupenagunta et al., 2011; sarathchandiran, 2012; fu et al., 2014; mahmood et al., 2020). 3.2 determination of %eciency of encapsulation (%ee) percentage analysis of %ee solid lipid nanoparticles loading erythromycin was carried out by determining the amount of in-direct encapsulated erythromycin. the highest %loading, the most loading substance. result showed that the f2 had the higher %ee (table 2). determination of the %ee starting with a separation process using the centrifuge (12,000 xg for an © 2022 the authors. page 197 of 201 mardiyanto et. al. science and technology indonesia, 7 (2022) 195-201 half hour). preparations that have been centrifuged will form 2 phases, namely the adsorbed part and the remaining part. the adsorbed part is amount of substance/drug that is loaded in the preparation as white sedimentation. the non-adsorbed part is the amount of substance/drug that is not loaded, usually a clear liquid that has separated. upper part has been used and analyzed by a uv-vis spect to calculate the amount of the unloaded drug. co-blockpolymer is a non-ionic type of stabilizer that can minimize the surface interaction (mardiyanto et al., 2021; kurniawan and audita, 2021) for facilitating the wetting process of surface of erythromycin, therefor could enhance the %ee. according to amount of stearic acid in f2, stabilizer support with the simultaneous formation of oil/water globule and speed the spread of form in water media and also have naturally amphiphilic abilities and can interact to relatively high amounts of non-soluble drug components. polysorbate80 can perform a strength layer around the particle surface, so that it can be inhibited the agglomeration and enhanced the %ee (figure 2 illustrated the structure of particles). the used of polysorbate-80 to the non-soluble drug can enhance the solubility of drug. this is according to a reduction in the interfacial tension thereby enhance the drug particles. the change of the drug’s surface leads to the solubility eect. the using of stabilizer at the certain amount can also reduce the contact of angles between drug and water. on the other hand, after reaching the critical micelle concentration, the amount of surfactant adsorbed decreased with increasing surfactant concentration. the amount of polysorbate-80 can cause the formation of aggregates. sln have been produced and stabilizedbypolysorbate-80butalsocouldbebrokenorbedamaged because the process is inuenced by the aggregation so that it can decrease the eciency of encapsulation. the results of the %ee for each formula were then analyzed by statistical data analysis using spssr 24 that f2 was signicant dierence to f1 and f3 at p<0.5. table 2. results of %ee sln erythromycin formula erythromycin (g) average %ee±sd cv (%) f1 0.025 75.178±0.131 0.153 f2 0.050 80.898±0.114 0.223 f3 0.100 26.201±0.174 0.663 3.3 physical properties of lipid particles loading erythromycin the choosing formula (f2) for solid lipid nps was further characterized and evaluated. characterization was carried out to ensure that the preparations made were relevant to the desired character of the requirements. characterization of the choosing formula for solid lipid nanoparticle loading erythromycin was included in the visualization of particles morphology and measurement of average diameter, pdi, and z. the principle of the technique of psa is used light scattering as dynamically by a light scatter. then the light was refracted figure 2. illustration of lipid particles loading erythromycin at several angles while in horiba sz-nano is linked to the two main detectors (<90◦ and >90◦) for producing diameter and pdi data also z. the tiny particle size is related to increasing the surface area and solubility rate and nally enhancing the bioavailability of the drug. diameter and pdi of f2 were 518.6 nm; 0.096 pdi; and a z value of -12 mv respectively. the surface visualization of sln was imaged by microscope in nano-scale, at the figure 3 was presented the image of particles diameter of 420 nm. according to the un-similar technique in measurement image utilizing this microscope and dierent manual of sem and psa, therefore the precise of using this microscope was more appropriate and also by sem the environment of sln such as no-moisture than the dls method. figure 3. sem image of sln loading erythromycin 3.4 evaluation of ph determination of the ph of solid lipid nanoparticles was performed by calculating the ph by utilizing a ph meter. the purpose of using a ph meter is to take an appropriate and accurate value than the other method such as strips-ph. according to the calculating results, in general, it tended that the ph value was slightly lower than neutral (ph of 6.00 – 7.00). the value of ph was presented in table 3 that the ph values were still appropriate for oral dosage-forms because they are close to neutral (ph 7). 3.5 physical stability test the stability test of the solid lipid nanoparticle preparation of erythromycin was carried out by the thermal and mechanical © 2022 the authors. page 198 of 201 mardiyanto et. al. science and technology indonesia, 7 (2022) 195-201 table 3. result of physical stability and ph determination cycles formula 1 formula 2 formula 3 visual ph visual ph visual ph 0 suspension 5.54±0.024 suspension 5.62±0.024 suspension 5.64±0.024 1 suspension 5.75±0.024 suspension 5.95±0.024 suspension 6.07±0.024 2 suspension 5.80±0.024 suspension 6.04±0.024 suspension 6.12±0.024 3 suspension 5.83±0.024 suspension 6.17±0.024 suspension 6.13±0.024 4 suspension 5.88±0.024 suspension 6.18±0.024 suspension 6.20±0.024 5 aggregation 6.24±0.024 suspension 6.19±0.024 aggregation 6.42±0.024 6 aggregation 6.49±0.024 aggregation 6.20±0.024 aggregation 6.88±0.024 methods. the observations were carried out using the solid lipid nanoparticles which were kept for overnight at a chilling and warming temperature side-by-side cycle of 1 week to determine the changing of the physical stability of sln as organoleptic and value of ph. this process was applied to observe the changes in preparations with dierent temperatures as an accelerated test. the changes were observed such as organoleptic and ph levels of stability of the sln loading erythromycin. based on the observations which were shown in table 3, organoleptically it was seen that the preparation was quite stable to dierent storage temperatures which were indicated by the physical appearance in terms of color-changing of sln and the formation of aggregation. observations on the ph level revealed a decreasing value in each test cycle. the results of ph measurements for each cycle were statistically analyzed using the ibm spssr 25 software. the stability ph data were rst tested for requirements, namely the normality test also the shapiro-wilk revealed for the sig value > 0.05 which indicates that the data regarding the value of ph were normally distributed to each f. stability tests were also performed mechanically using a centrifuge. the principle of the process of the centrifugation method is the un-stable sln will follow the aggregation formed by the time because of the surface interaction of each particle. the suspension/emulsion dosage-form are based on physical stability requirements. this requirement is mimic the real condition of distribution and storage of suspension/emulsion. centrifugation is rotated int high rpm leads to change in term of the outer surface of the dispersed particles (dis-continues phase) and stimulate coalescence (combined into pellets formation). 3.6 solubility test solubility testing of solid lipid nanoparticles carrying erythromycin was carried out on the selected formula which purpose to evaluate the enhancing solubility of the sln loading erythromycin using several solutions for dosage-form manufacturing and the solution which locates in the part of the human body. the results were presented in table 4. the test solutions used in the solubility test of nanoparticle preparations correspond to some of the solutions in the gastric and intestine. the aims of utilizing the solvent were to see some resistances of the preparation as well as to determine the route for administering drugs that are suitable for the body so that the solid lipid nanoparticle preparation can reach the desired target. the sample solutions used in testing the solubility of solid lipid nanoparticle preparations were distilled water, sodium hydroxide, sodium bicarbonate, acid chloride, articial gastric solution, and intestine solution. the use of the test solution above aims to condition the same solution as that in the body especially sif in the intestine as the target location of absorption for erythromycin. as much as 50 mg erythromycin was not soluble in 2 ml of sif but when in the form of 50 mg of erythromycin loaded by lipid particles was soluble in sif. table 4. results of solubility test of sln loading erythromycin no. solvent visualization criteria 1 sif clear soluble 2 naoh turbid not soluble 3 hcl clear soluble 4 sgf clear soluble 5 nahco3 turbid not soluble 6 water for injection turbid not soluble the increasing in stabilityand solubilityof antibiotics in the formofparticleshasbeenwidelystudiedusing lipid, plgaand chitosan-alginate polymers (bhattacharyya and reddy, 2019). the small particle size (as the results were presented in the particle size and distribution) impacts to the increasing of surface area as well as solubility (mardiyanto et al., 2021; fonsecasantos et al., 2020). while the stability eect depends on the particle manufacturing process. the encapsulation process is known to provide a coating and protective eect. encapsulation of erythromycin in this study of lipid particles was around 80% as described and shown in table 2. this eect can also be exerted by several polymers such as plga, chitosan, alginate etc which are semipolar and stearic acid which is non-polar. since the outer medium is water, nonpolar polymers are last longer and display higher stability than semi-polar ones. the hydrophilic groups of semipolar polymers will interact with water. instability can be seen from changing in ph due to the exposure of hydroxyl and carboxyl groups in water as a sign © 2022 the authors. page 199 of 201 mardiyanto et. al. science and technology indonesia, 7 (2022) 195-201 that the particle formation has changed. these data are presented in tables 2 to 4 and are supported by several figure 1 to 3. 4. conclusions this research has selected formula of f2 which had a high percentage of encapsulation eciency of 80.89773±0.11364. the physical characterization of particle formation such as morphology, diameter (particle size) and distribution (pdi) of f2 were spherical 518.6 nm; 0.096 pdi; and a zeta potential value of -12 mv respectively. the particles could increase the stability of erythromycin for up to 5 cycles in terms of the heating-cooling-cycles test and also the solubility in sif. 5. acknowledgment author conducted this research by utilizing the research funding of “kompetitif” research scheme of 2022 sriwijaya university (unsri). the sln formulation also evaluation were performed at laboratoryof technology-pharmacyat department of pharmacy, fmipa unsri, centre of drug and cosmetics evaluation of uii, also the laboratory of particles chemistry of ugm. references almanassra, i. w., e. c. okonkwo, o. alhassan, m. a. atieh, v. kochkodan, and t. al-ansari (2021). stability and thermophysical properties test of carbide-derived carbon thermal fluid; a 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(2012). a review on nanotechnology in solid lipid nanoparticles. international journal of pharmaceutical development technology, 2(1); 45–61 vabre, c., c. jurado, and f. eyvrard (2020). modalités de délivrance des anti-infectieux: un outil pour assurer la continuité de soins en fin d’hospitalisation. le pharmacien hospitalier et clinicien, 55(4); 348–363 wang, l., s. lu, y. deng, w. wu, l. wang, y. liu, y. zu, and x. zhao (2021). pickering emulsions stabilized by luteolin micro-nano particles to improve the oxidative stability of pine nut oil. journal of the science of food and agriculture, 101(4); 1314–1322 wong, c. h., k. w. siah, and a. w. lo (2020). estimating probabilities of success of clinical trials for vaccines and other anti-infective therapeutics. medrxiv; 1–25 © 2022 the authors. page 201 of 201 introduction experimental section materials laboratory work preparation of lipid and water phase formula formation of lipid particles loaded erythromycin purification and determination of indirect encapsulation measurement of product acidity characterization of physical properties of particles thermodynamic and mechanic test of stability solubility test results and discussion formation of nanoparticle loading erythromycin determination of %efficiency of encapsulation (%ee) physical properties of lipid particles loading erythro-mycin evaluation of ph physical stability test solubility test conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper variation of m2+ (ni and zn) in cellulose-based m2+/cr composite materials to determine adsorption and regeneration abilities on phenol removal alfan wijaya1, tarmizi taher2,4, aldes lesbani3,4, risfidian mohadi1,4* 1magister programme graduate school of mathematics and natural sciences, sriwijaya university, palembang, 30139, south sumatera, indonesia2department of environmental engineering, faculty of mathematics and natural sciences, institut teknologi sumatera, lampung, 35365, indonesia3graduate school of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia4research centre of inorganic materials and coordination complexes, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, south sumatera, indonesia *corresponding author: risfidian.mohadi@unsri.ac.id abstractcellulose-based ni/cr (ni/cr-c) and cellulose-based zn/cr (zn/cr-c) composite materials have been successfully carried out, whichis indicated by the xrd, ftir, and bet analysis. layered double hydroxide ni/cr (ni/cr-ldh) increased surface area from 0.128m2/g to 2.207 m2/g in ni/cr-c composites, and layered double hydroxide zn/cr (zn/cr-ldh) also increased surface area from 0.133m2/g to 3.714 m2/g in zn/cr-c composites. the phpzc of the material in this study is ph 5.94-8.43, while the optimum ph of allmaterials is ph 9. ni/cr-ldh experienced an increase in adsorption capacity after becoming a ni/cr-c composite, from 8.985 mg/g to24.510 mg/g, and zn/cr-ldh experienced an increase in adsorption capacity from 13.263 mg/g to 30.960 mg/g in zn/cr-c. zn/cr-ccomposite material has a greater adsorption ability than ni/cr-c. kinetic and isotherm model in this study followed by pso kineticwith optimum contact time at 70 minutes and freundlich isotherm. ni/cr-c and zn/cr-c composite materials can be used repeatedlyin the regeneration process until the 4th cycle. keywordsldh, cellulose, composites, adsorption, phenol, regeneration received: 21 july 2022, accepted: 10 october 2022 https://doi.org/10.26554/sti.2022.7.4.461-468 1. introduction layered double hydroxide (ldh) is one of the layered materials which have a general structure [m2+1−x m3+x (oh)2]2+ [an−x/n. m h2o] with excellent ion exchange capacity, large specic surface area, controllable morphology, and electropositive surface, making ldh a suitable material for adsorption of organicpollutants, cationicoranionicdyes, antibioticmolecules, and heavy metal ions (wang et al., 2022; yuliasari, 2022). however, the layered double hydroxide structure is less stable and the layer is easilypeeled o during the repeated use process. this material allows it to be modied to be used repeatedly and improve performance. one way of modication is by composting with carbon-based materials such as cellulose. based on research conducted by sun et al. (2022), cellulose/mgal composites layered double hydroxides (ldhs) have a high specic surface area which is benecial for the adsorption process. cellulose also has a large pore structure and includes green and eco-friendly adsorbents. this study used composite materials to remove phenols, including harmful organic pollutants. phenol is a volatile organic compound (voc) that is very harmful to the environment, humans, and other living things even at low concentrations of less than 1.0 `g/l because it is highly toxic and carcinogenic. phenols are found in many sources such as the petrochemical industry, medical wastewater, coal conversion, wood products, paint, pesticides, and paper industries (chaghaganooj et al., 2021; dong et al., 2021; da silva et al., 2022; gao et al., 2022). therefore, it is important to carry out treatment for the removal of this phenol organic pollutant. phenol removal method in this study using adsorption method. adsorption method is a widely used technique for managing organic pollutants because it has many advantages such as eco-friendly, economic feasibility, cost-eectiveness, simplicity, exibility, and high eciency (ullah et al., 2022; sahu et al., 2021; dehmani et al., 2022). this studymodied the composite material byvarying m2+ on the composite material cellulose-based m2+/cr to see the adsorption and regeneration abilities in removing phenol organic pollutants. juleanti et al. (2021) conducted a study by https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.461-468&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.461-468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 varying m2+ (ca and mg) on m2+/al-based biochar composite materials which showed dierences in adsorption ability, where biochar-based ca/al has a greater adsorption capacity compared to biochar-based mg/al. composite materials prepared in this study are proven by characterization data, including xrd, ft-ir, and bet. this research was conducted with several treatments and parameters such as the inuence of ph, adsorption contact time, eect of initial concentration and temperature on the adsorption process, isotherm, and thermodynamic parameters. 2. experimental section 2.1 chemicals and instrumentation the materials used in this study such as ni(no3)2.6h2o, zn(no3)2.6h2o, cr(no3)3.9h2o, distilled water, phenol (c6h5oh), 4-amino antipyrine (c11h13n3o), potassium hexacyanoferrate (iii) (k3[fe(cn)6]), buer solution ph 10, hcl, and naoh. the synthesized material was characterized using an x-ray rigaku miniex-600 diractometer, shimadzu prestige-21 ftir spectrophotometer, bet surface area analyzer micrometric asap quantachrome, and absorbance measurement of solution using biobase spectrophotometer uvvisible bkuv1800pc. 2.2 synthesis of ni/cr-ldh and zn/cr-ldh synthesisofni/cr-ldhwascarriedoutwithni(no3)2.6h2o 0.75 m solution of 100 ml mixed with 100 ml cr(no3)3. 9h2o 0.25 m. then added 2 m sodium hydroxide (naoh) solution slowlyup to ph 8 and heated at a temperature of 60°c. constant stirring was performed for 12 hours at a temperature of 80°c. the obtained precipitate was ltered and washed using aqueous to a neutral ph. the residue was dried for 24 hours using an oven at 60°c. synthesis of zn/cr-ldh was carried out with zn(no3)2.6h2o solution of 100 ml mixed with 100 ml cr(no3)3.9h2o (ratio molar 2:1), and then a mixture of na2co3 2.5 m and naoh 2 m solutions is slowly added to ph 10 and then stirred for 2 hours. the mixture is heated at 60°c for 24 hours. the obtained precipitate was ltered and washed using aqueous to a neutral ph and dried using an oven at 60°c for 24 hours. the synthesized materials were characterized using xrd, ft-ir, and bet analysis. 2.3 preparation of ni/cr-c and zn/cr-c composites composite materials were prepared using the method of coprecipitation with a constant ph. a total of 30 ml of ni(no3)2. 6h2o or zn(no3)2. 6h2o 0.75 m solution and 30 ml of cr(no3)3. 9h2o 0.25 m solutions were mixed and set ph to 10 using a solution of naoh 2 m. the mixture was stirred for 1 hour, then 3 g of cellulose was added. the solution is heated at a temperature of 80°c for 3 days. the precipitate was ltered and dried using the oven at 80°c for 24 hours. the prepared materials were characterized using xrd, ft-ir, and bet analysis. 2.4 study of ph point zero charge (phpzc) the study of phpzc was performed by adding 0.02 g of adsorbent each to 20 ml of nacl solution with a concentration of 0.1 m which has been ph-regulated with ph variations of 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. nacl solution is ph regulated by adding a solution of naoh and hcl with a concentration of 0.1 m. the mixture is stirred for 24 hours, then ltering is carried out and the ltrate is measured at the nal ph using a ph meter. determining the phpzc of each material was carried out by graphing the relationship between the initial ph and the nal ph. 2.5 adsorption process theadsorptionprocess in this studywascarriedoutwithseveral treatments, such as the inuence of ph, adsorption contact time, andthe inuenceof initial concentrationandtemperature on the adsorption process. the eect of ph adsorption can be studied by performing a phenol adsorption process on ph variations (2-11) which aims to determine the optimum ph in the adsorption process. as much as 0.02 g adsorbents were added to an erlenmeyer containing 20 ml of phenol solution with a concentration of 10 mg/l and the mixture was stirred for 2 hours. the eect of contact time adsorption on phenol can be studied by varying the contact time to determine the optimum time. as much as 0.02 g adsorbents were added to an erlenmeyer containing 20 ml of phenol solution with a concentration of 10 mg/l and the mixture was stirred. the eect of initial concentration and temperature adsorption was studied by varying the concentration (10, 15, 20, 25, and 30 mg/l) and temperature (30, 40, 50, 60, and 70°c). as much as 0.02 g adsorbents were added to an erlenmeyer containing 20 mlof phenol solution and stirred during the optimum time. the ltrate was measured using a uv-vis spectrophotometer. the ltrate of the phenol solution was complex rst before measuring its absorbance. as much as 1 ml phenol solution was put in a beaker and then a 4-amino antipyrine reagent solution of 2% was added to as much as 0.1 ml, an 8% solution of potassium hexacyanoferrate (iii) as much as 0.1 ml, the solution of ph 10 buer of 1 ml was added and 3 ml was added, then homogenized and allowed to stand for 15 minutes. 2.6 desorption process and study of regeneration ability the desorption process is carried out before the adsorbent regeneration process. the desorption process is performed on adsorbents that have been adsorbents that have been adsorbed phenol by using an ultrasonic system. after the desorption process, the regeneration process was carried out by adding 0.1 g of adsorbent to a phenol solution of 10 mg/l then stirred for 2 hours and the absorbance of the ltrate was measured using a uv-visible spectrophotometer and adsorbents dried in the oven. the dried adsorbent was carried out in the desorption process, then the regeneration process was carried out for the next cycle. © 2022 the authors. page 462 of 468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 figure 1. diraction patterns of ni/cr-ldh (a), zn/cr-ldh (b), cellulose (c), ni/cr-c (d), and zn/cr-c (e) 3. result and discussion the results of the xrd characterization analysis can be seen in figure 1. based on gure 1, ni/cr-ldh has a diraction peak at an angle of 11.4° (003), 23.3° (006), 34° (009), and 60.8° (110). padalkar et al. (2022)) reported that ni/cr-ldh had diraction peaks at angles of 11° (003), 23° (006), and 60° (110) according to jcpds data (74-1057). peak diraction at zn/cr-ldh appeared at angles of 11.74° (003), 23.49° (006), 34.33° (009), 39.26° (012) and 60.41° (110) according to jcpds data (51-1525). according to liu et al. (2018), typical diraction peaks at angles of 11° (003) and 22° (006) indicate that the layered double hydroxide material is a layered material. the peaks of diraction in cellulose shown in figure 1 appear at angles of 15.19° (110), 22.67° (200), and 34.49° (004) which have similarities to the study conducted by debnath et al. (2022). the successful modication of layered double hydroxide materials to form ldh-cellulose composites were evidenced by the emergence of layered double hydroxide diraction peaks and cellulose in composite materials. ni/crc composites have diraction peaks at angles of 11° (003) and 60.3° (110) which are typical peaks of ni/cr-ldh and peaks at angles of 22.88° (200) known to be characteristics peaks of cellulose. the diraction peaks that appear on the zn/crc composite at angles of 11.62° (003) and 59.86 (110) are known to be typical peaks of zn/cr-ldh and at an angle of 22.90° (200) are t characteristics peaks of cellulose. the results of the ft-ir analysis can be seen on the ftir spectrum shown in figure 2. based on the ft-ir spectra in figure 2, it can be seen that all materials have widened vibrations in the area of 3500-3200 cm−1 which indicates the presence of an -oh group of water molecules. vibrations figure 2. ft-ir spectrum of ni/cr-ldh (a), zn/cr-ldh (b), cellulose (c), ni/cr-c (d), and zn/cr-c (e) that appear in layered double hydroxide materials in the wave number area of 1380 cm−1 indicate the presence of an n-o group of nitrates and in regions around 600-700 cm−1 indicate the presence of metal bonds with oxygen (m-o). vibrations that appear in cellulose in regions around 3000-2850 cm−1 indicate the presence of aliphatic -ch from alkanes and in areas of 1030 cm−1 indicate the presence of a c-o-c group in cellulose. based on figure 1, the ldh-cellulose composite materialappears tobeatypicalvibrationcombinedwith layered double hydroxide and cellulose materials. the vibration that occurs in the region of about 1380 cm−1 (n-o) in the area of about 600-700 cm−1 (m-o) is known as a typical vibration of layered double hydroxide, while the vibration that appears in the wave number area 3000-2850 cm−1 (-ch aliphatic) and in the area 1030 cm−1 (c-o-c) is a typical vibration of cellulose. based on the bet analysis data in figure 3, it can be seen that each material shows a type iv isotherm based on the iupac classication with the presence of particles of mesoporous size with hysteresis activity. hysteresis activity shows the material has non-uniform pores, so that the graph between adsorption and desorption occurs a dierence. based on the data from the measurement results of the bet analysis in table 1, it can be seen that there is an increase in the surface area of the layered double hydroxide after being composted with cellulose. ni/cr-ldh increased surface area from 0.128 m2/g to 2.207 m2/g in ni/cr-c composites and zn/cr-ldh also increased in surface area from 0.133 m2/g to 3.714 m2/g in zn/cr-c composites. based on these data, it can also be seen that zn/cr-ldh and zn/cr-c have a larger surface area than ni/cr-ldh and ni/cr-c. based on the results of the characterization analysis of xrd, ft-ir, and bet, it is proven © 2022 the authors. page 463 of 468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 table 1. data of bet analysiss adsorbents surface area (m2/g) pore volume (cm3/g) pore diameter (nm) ni/cr-ldh 0.128 0.042 15.124 zn/cr-ldh 0.133 0.001 0.003 ni/cr-c 2.207 0.004 1.691 zn/cr-c 3.714 0.006 1.564 figure 3. bet prole of ni/cr-ldh (a), zn/cr-ldh (b), ni/cr-c (c), and zn/cr-c (e) that the preparation process of layered double hydroxide composites with cellulose has been successfully carried out, which is characterized by the emergence of peaks of diraction of layered double hydroxide and cellulose in composite materials and an increase in surface area in composite materials. the material in this study carried out a phpzc test with the test results shown in figure 4. based on the results of the ph pzc test on each material, it is known that the ph pzc on materials ni/cr-ldh, zn/cr-ldh, cellulose, ni/cr-c, and zn/cr-c is 6.68, 8.43, 7.46, 6.92, and 5.94, respectively. each material was also carried out a ph test in the phenol adsorption process to determine the optimum ph with the test results that can be seen in figure 5. based on figure 5, it can be seen that the optimum ph of all materials in the phenol adsorption process is ph 9. the materials were tested on the inuence of adsorption contact time on the phenol adsorption process, which aims to determine the optimum adsorption time. adsorption contact time was measured with a time variation of 0-180 minutes. based on figure 6, the equilibrium time of the adsorption process occurs at 70 minutes with an insignicant increase in adsorption concentration. table 2 shows the adsorption kinetfigure 4. ph pzc of materials figure 5. eect of ph on adsorption process © 2022 the authors. page 464 of 468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 table 2. adsorption kinetic parameters pfo pso adsorbents initial concentration (mg/l) qeexp (mg/l) qecalc (mg/l) r 2 k1 qecalc (mg/l) r 2 k2 ni/cr-ldh 2.616 1.935 0.959 0.034 2.846 0.998 0.026 zn/cr-ldh 4.100 3.755 0.927 0.045 4.627 0.988 0.013 cellulose 10.059 3.618 1.684 0.904 0.032 3.798 0.999 0.035 ni/cr-c 5.167 3.178 0.969 0.037 5.495 0.999 0.019 mg/cr-c 6.058 5.261 0.946 0.046 6.780 0.992 0.009 figure 6. adsorption kinetic models ics followed by pso through the value of the linear regression coecient (r2), close to the value of 1, and qecalc in pso is closer to qeexp than in pfo. furthermore, each material was tested for the eect of initial concentration and temperature on the phenol adsorption process. basedongure7, it isknownthat themoretheconcentration and temperature increase, the adsorbed concentration also increases. from the test of the inuence of the initial concentration and temperature that has been carried out can be determined isotherm and thermodynamic parameters with the results of the data shown in tables 3 and 4. based on table 3, it can be seen that the adsorption capacity of each material where in ni/cr-ldh experienced an increase in adsorption capacity after becoming a ni/cr-c composite, from 8.985 mg/g to 24.510 mg/g, the same also happened in zn/cr-ldh experienced an increase in adsorption capacity from 13.263 mg/g to 30.960 mg/g. based on table 3, the freundlich model is better than the langmuir model for the adsorption process in this study, with the value of r2 closer to the value of 1. this indicates that the adsorption process occurs multilayer. based on table 4, it can be seen that 4g value overall shows negative values indicating a spontaneous adsorption process, 4h value shows positively that the adsorption process is endothermic, with the enthalpy value in the 1.459–6.975 kj/mol range indifigure 7. eect of initial concentration and temperature on adsorption process using ni/cr-ldh (a), zn/cr-ldh (b), cellulose (c), ni/cr-c (d), and zn/cr-c (e) cating the physical adsorption process and 4s shows degrees of irregularity. the regeneration ability test on the material was also tested in this study to see the stability and eectiveness of the material. based on gure 8, it can be seen that ni/cr-ldh and zn/cr-ldh materials can only be used repeatedly for 2nd cycle while in ni/cr-c and zn/cr-c composite materials can survive the regeneration process until the 4th cycle. this proves that the preparation process of ldh-cellulose composites can improve material performance in repeated use. a comparison of adsorption ability of phenol by several adsorbents can be seen in the table 5. based on table 5, it can be seen that the adsorbent ability in ni/cr-c and zn/cr-c composite materials is superior to other adsorbents as evidenced by the large adsorption capacity and the optimum contact time, which is quite fast, which is 70 minutes. figure 9 shows a plausible illustration of the m2+ dierence on cellulose-based m2+/cr composite materials, where the use of m2+ with a larger atomic radius will aect the formation of interlayer space. the radius of atoms in m2+ or m3+ is larger, causing the appearance of a small interlayer space, and vice versa. it aects the adsorption ability of the material as evidenced by adsorption data where zn/cr-c composite material has a greater adsorption ability than ni/cr-c. © 2022 the authors. page 465 of 468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 table 3. adsorption isotherm parameters temperature adsorbents adsorption isotherm adsorption constant 30°c 40°c 50°c 60°c 70°c qmax 2.055 2.968 3.893 6.146 8.985 langmuir kl 0.063 0.061 0.058 0.053 0.048 ni/cr-ldh r2 0.855 0.875 0.906 0.955 0.952 n 0.238 0.275 0.306 0.365 0.412 freundlich kf 2.424 2.066 1.862 1.608 1.472 r2 0.947 0.941 0.943 0.960 0.940 qmax 9.606 13.263 6.382 7.380 6.135 langmuir kl 0.046 0.041 0.101 0.111 0.173 zn/cr-ldh r2 0.971 0.976 0.977 0.978 0.981 n 0.446 0.498 0.539 0.602 0.686 freundlich kf 35.530 17.923 11.130 6.206 3.388 r2 0.995 0.996 0.994 0.994 0.993 qmax 6.925 9.542 13.245 7.097 8.110 langmuir kl 0.051 0.046 0.041 0.102 0.112 cellulose r2 0.965 0.977 0.977 0.982 0.987 n 0.407 0.456 0.503 0.588 0.653 freundlich kf 13.868 11.150 10.495 7.244 4.383 r2 0.999 0.999 0.997 0.997 0.998 qmax 24.450 24.510 24.510 23.095 22.676 langmuir kl 0.189 0.227 0.278 0.428 0.601 ni/cr-c r2 0.886 0.902 0.950 0.972 0.984 n 0.784 0.847 0.892 1.000 1.126 freundlich kf 1.946 1.377 1.057 1.386 1.989 r2 0.912 0.910 0.943 0.939 0.937 qmax 30.960 28.571 27.100 26.525 25.381 langmuir kl 0.116 0.161 0.218 0.277 0.386 zn/cr-c r2 0.856 0.909 0.918 0.941 0.958 n 0.848 0.969 1.097 1.201 1.394 freundlich kf 1.363 1.157 1.699 2.227 3.121 r2 0.961 0.966 0.979 0.970 0.983 table 4. adsorption thermodynamic parameters adsorbents concentration (mg/l) t (k) qe (mg/g) 4h (kj/mol) 4s (j/mol. k) 4g (kj/mol) 303 15.078 -0.011 313 15.226 -0.070 ni/cr-ldh 30.082 323 15.412 1.794 0.006 -0.130 333 15.579 -0.190 343 15.681 -0.249 303 15.152 -0.012 313 15.338 -0.121 zn/cr-ldh 30.082 323 15.607 3.275 0.011 -0.229 333 15.950 -0.338 343 16.275 -0.446 303 15.208 -0.060 313 15.403 -0.111 cellulose 30.082 323 15.495 1.459 0.005 -0.161 333 15.523 -0.211 343 15.783 -0.261 303 17.072 -0.698 313 17.768 -0.952 ni/cr-c 30.082 323 18.455 6.975 0.025 -1.205 333 18.863 -1.458 343 19.410 -1.711 303 17.629 -0.862 313 18.176 -1.112 zn/cr-c 30.082 323 18.724 6.698 0.025 -1.361 333 19.327 -1.611 343 19.790 -1.860 © 2022 the authors. page 466 of 468 wijaya et. al. science and technology indonesia, 7 (2022) 461-468 table 5. regeneration ability of materials adsorbents adsorption capacity (mg/g) optimum contact time references date palm bers 19.57 24 hours (alminderej et al., 2022) natural clays 10 2 hours (dehmani et al., 2021) moroccan clay 15.11 2,5 hours (dehmani et al., 2020) fe3o4/chitosan/zif-8 nanocomposit 6.43 40 minutes (keshvardoostchokami et al., 2021) hematite iron oxide nanoparticles 5.35 2 hours (dehbi et al., 2020) activated carbon from palm kernel shell 23.82 (hernández-barreto et al., 2020) unactivated moringa oleifera seed shells residue 6.95 (sani et al., 2020) aluminum oxide nanoparticles 16.97 (safwat et al., 2022) banana peels activated carbon 6.98 1 hour (ingole et al., 2017) biochar from the pine fruit shells (bc550) 26.738 1 hour (ingole et al., 2017) rice husk activated carbon 28 (mohammad et al., 2014) diethylenetriamine modied activated carbon 18.12 (saleh et al., 2018) zn4al-ldh 23.4 1 hour (lupa et al., 2018) ni/cr-c 24.51 70 minutes this study zn/cr-c 30.96 70 minutes this study figure 8. regeneration ability of materials figure 9. plausible illustration of m2+ dierence on cellulose-based m2+ /cr composite 4. conclusion ni/cr-c and zn/cr-c composite materials have been successfully carried out, as evidenced by xrd, ftir, bet analysis, increased surface area, adsorption ability, and regeneration ability. ni/cr-c and zn/cr-c composite materials can be used repeatedly on the regeneration process until the 4th cycle. based on adsorption data, zn/cr-c composite material has a greater adsorption ability than ni/cr-c. kinetic and isotherm model in this study followed by pso kinetic and freundlich isotherm. 5. acknowledgment the 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(2022). modication of mg/alldh intercalated metal oxide (mg/al-ni) to improve the performance of methyl orange and methyl red dyes adsorption process. science and technology indonesia, 7(3); 275– 283 © 2022 the authors. page 468 of 468 introduction experimental section chemicals and instrumentation synthesis of ni/cr-ldh and zn/cr-ldh preparation of ni/cr-c and zn/cr-c composites study of ph point zero charge (phpzc) adsorption process desorption process and study of regeneration ability result and discussion conclusion acknowledgment subject index vol. 3 no.1 january 2018 a alloxan al2o5 catalyst antidiabetic b bacillus cereus biogas bioremediation c catalytic cracking process characteristic function compound geometric distribution co-processed excipient cow manure custom design ctab d definite positive degradation e ethanol extract extract g gamma distribution h heavy metal k kleinhovia hospital l l lansium domesticum local rice varieties of south sumatera m methane morphology diversity p plastic waste polystyrene pome promega s seri leaves simplex lattice design south sumatera spent bleaching earth (sbe) standarization t textile w waste water research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 3 (2018) 26-29 © 2018 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 22 november 2017; revised 16 january 2018; accepted 16 january 2018 http://doi.org/10.26554/sti.2018.3.1.26-29 comparison of ctab method and wizard genomic dna purification system kit from promega on dna isolation of local varieties of rice of south sumatera laila hanum1*, yuanita windusari1, arum setiawan1, muharni1, fikri adriansyah1, amin ali mubarok1 1departement of biology, mathematic and science faculty, sriwijaya university *corresponding author e-mail: lailahanum@ymail.com abstract research in the molecular field requires dna with a high degree of purity. local rice varieties of south sumatra have different leaf texture so that in isolation process to obtain dna with high purity level required the right method. this study aims to compare the quality and quantity of purity of local rice insulation of local rice varieties of south sumatra with different methods of ctab and wizard genomic dna purification system kit from promega. the research was conducted from august 2015 to december 2015 at the laboratory of microbiology and genetics and biotechnology laboratory, department of biology, faculty of mathematics and natural sciences, sriwijaya university. the method used is dna isolation method wizard genomic dna purification system kit from promega and ctab. based on research that has been done result of dna visualization showed that dna isolate ctab method still have smears while dna isolate method of wizard genomic dna purification system kit from promega not. the average dna isolate concentration of wizard genomic dna purification system kit method is a260 / 280 = 1.853 μg / ml. the average dna isolate concentration of ctab method is a260 / 280 = 1,705 μg / ml. isolation of rice dna of local variety of south sumatera using dna method of genomic dna purification system kit from promega has higher quality and quantity compared to ctab method. keywords: ctab, local rice varieties of south sumatra, promega 1. introduction local rice varieties of south sumatra have superior properties that are not owned by superior rice varieties. these properties are stored in genes. this property is an important source of germplasm to be maintained. in addition, genetic information can be used as a base material in the process of plant breeding. the genetic information of a plant variety can be known by the pcr technique. dna isolation was the first step in molecular analysis of pcr (restu et al., 2012). the purity of target dna is very important in the pcr process, since impurities of dna suspension can affect the amplification reaction and may inhibit the action of dna polymerase enzymes. selection of the target to be amplified should take into account the genetic stability of the targeted region or nucleotide sequence (fatchiyah et al., 2011).this study aims to compare the results of isolation of local rice varieties of rice with different methods of ctab method and wizard genomic dna purification system kit from promega. so as to determine which type of method is appropriate for dna isolation. high quality and high quantity of dna and free of contaminants can be used for other studies using pcr. 2. experimental section 2.1. materials and equipments the tool used in this research is stationery, aluminum foil, analytical scale, ice box, glove, mortar, pestle, mikropipet, yellow tip, microsentrifus, microtube size 0.2 ml and 1.5 ml, hot plate, spectrophotometer, thermo-cycler, waterbath, and wizard genomic dna purification system kit from promega and ctab. materials needed are for dna isolation is the local rice leaf of local varieties of south sumatra (table 1), ice, ethanol 70%, ethanol 96-100%. 2.2. dna isolation method wizard genomic dna purification system kit from promega the leaves are frozen in the freezer as much as 0.1 gr. then finely crushed while added nuclei lisis solution (nls) 600 μl then put in eppendof tube size 0,5 μl and in vortex for 3 second. incubated hanum et al. 2018 / science & technology indonesia 3 (1) 2017: 26-29 27 in water bath for 15 minutes at 650c. added 200 μl pps then divortex for 20 seconds. then centrifuged at 13,000 rpm for 3 minutes. supernattan is transferred into 600 μl isopropanol (0.6) volume. mix the solution until you see the white thread of dna. then centrifuged at 13,000 rpm for 1 minute. supernattan was removed and 600 μl of ethanol was added 70%. wash the dna by centrifuging at 13,000 rpm for 1 minute. discard the supernattan and then dry the dna for 15 minutes. finally added 100 μl of drs dna and store dna at a temperature of 2-80 c 2.3.ctab conducted by method of doyle and doyle (1987) in restu et al. (2012) modified. a total of 200 mg of leafless rice leaves plus 0,02 g of pvp were crushed until smooth (flour). the crushing results were then transferred into a 1.5 ml eppendorf tube, plus 0.5 ml of ctab extraction buffer (1.4 m nacl, 2% ctab, 50 mm edta, 1 m tris-hcl ph 8.0 and 0, 2% ß-mercaptoetanol). the process of lysis of the cell wall is done by incubating the tube containing the leaf sample into the temperature waterbath of 65oc for 60 minutes. the tube is lifted from the waterbath and allowed for several minutes until the sample temperature in the tube decreases. subsequently added chloroform: isoamilalcohol (cia 24: 1) 500 μl. the tube is shaken using a vortex, then centrifuged at 10,000 rpm for 10 minutes. the supernatant was transferred into a bar tub and then cold isopropanol was added as much as 1 volume, slowly flipped through until the dna thread was visible. the sample was then allowed to settle overnight in the refrigerator at 4 ° c. after being deposited overnight, the sample was then centrifuged for 15 minutes at 10,000 rpm. the pellets of dna formed at the bottom of the tube are then dried. after that 100 μl h2o was added and stored in refrigerator (-40 c). 2.4. electrophoresis weighed 0.5 gr of agarosa and then put into a erlenmeyer flask containing 50 ml of tae while shaking to dissolve. insert a magnetic stirel into the flask and heat on the hotplate until cooked. poured into a well comb which amounts to 8 wells on the first comb and 16 wells on the second comb slowly so as not to form bubbles. let stand until the gel or gel for ± 30 minutes and after cool comb then lifted. the 10 μl dna samples were pipetted and then inserted into the wells contained in the gel using a microphone. added 0.7 μl loading dye in the well. the gel is then fed into an electrophoresis tank that has been filled with a tae buffer. electrode connected with power supply at 100 volt voltage with ampere 400 ohm for 30 minutes then running done for 30 minutes. after running is done then pour 200 ml of tae and add a drop of etbr into aluminum foil coated container. inserted agarose gel into the container and then soaked for 15 minutes. 2.5. electrophoresis visualization of electrophoresis results visualization of the results running on the gel is done by using a uv transilluminator and the results are photographed as documentation. 2.6. quantification and quality of isolated dna result prior to use in pcr reactions, dna quantification was done to determine the purity and concentration of dna. quantification is done using genequant (life science, ltd., uk). a 2 μl isolated dna sample was fed into a quartet containing 1998 μl sterile aquabides and mixed homogeneously. the sample then calculated its concentration at wavelength (λ) 260 and 280 nm. comparison of concentrations at each wavelength is used as a benchmark of dna purity. dna purity is determined on the basis of the ratio of a260 / 280 = 1.8-2 [8]. dna quality testing can also be performed with agarose gel electrophoresis on genomic dna prior to pcr. dna quality is good when the dna bands appear clear, thick, there is only one band and no shadow under the band (smear) when compared to marker (sambrook et al., 1989) 3. results and discussion 3.1. ctab based on the results of electrophoresis (figure 1) and reinforced with the result of quantity test and dna quality test (table 2) shows the isolated dna with ctab method can still be used for the analysis of genetic variation by rapd method. although its purity is not in accordance with the specified standards. this is based on the ratio of concentration at each wavelength used as a benchmark of dna purity. dna purity was determined on the basis of the ratio of a260 / 280 = 1.8-2 (sambrook et al., 1989). the impure dna of the mold still contains rna which is marked by the presence of smears on the visualization result of the dna band. this will disrupt the primary attachment of the site and will inhibit the activity of dna polymerase enzymes. this enzyme serves to polymerize the dna while the molded dna that table 1. list of local varieties of rice soyth sumatra no. varieties code 1 padi pegagan pp 2 padi dayang rindu drmk 3 padi dayang kuning dkmk 4 padi seluang smk 5 padi panak/pendek pmk 6 padi pamulan/empat bulan pebmk 7 padi talang tb 8 padi sanapi sb 9 padi ketan itam kib 10 padi ketan putih kpb 11 padi ketan abang/ketan merah kab 12 padi dayang telasih dtllg 13 padi hitam hllg 14 padi pulut/meto tomok pllg1 15 padi putih pllg2 16 padi pengagat pllg3 17 padi dayang rindu drllg 18 padi pulut pm2si 19 padi panjang pm2s2 20 padi jambat thehas jtm2s 21 padi beram bm2s 22 padi stik sk hanum et al. 2018 / science & technology indonesia 3 (1) 2017: 26-29 28 many have fragmentation can eliminate the primary attachment site. based on the results of electrophoresis (figure 2) and reinforced by the result of quantity test and dna quality test (table 3) shows the isolated dna with wizard genomic dna purification system kit method from promega can be used for analysis of genetic variation by rapd method. this is based on the ratio of concentration at each wavelength used as a benchmark of dna purity. dna purity was determined based on the ratio of a260 / 280 = 1.8-2 (sambrook et al., 1989). 3.2. dna purification system kit from promega one of the advantages of the diversity analysis utilizing pcr technology is that the quantity of dna required is small (arif et al.,2010). the molded dna concentration used ranges from 1.5 to 25 ng in each pcr reaction. determination of the concentration of molded dna greatly affects the attachment of primers to the molded dna. high dna mold concentrations will result in poor dna amplification because the primers used are difficult to stick to. conversely, if the concentration of the molded dna is too low, there will be a competition where the primer attaches to the mold causing one of the fragments to be amplified in large quantities while the other fragment is slightly (pharmawati, 2009). the optimization of isolation and purification technique of dna on the betel nut plant (reutalis trisperma (blanco) obtained dna quantity ranged from 68.80-5.031.39 ng / μl with dna purity in the range of 1,8-1,9 with electrophoresis result showed intact dna marked with absence of dna smears) (syafarudin and santoso, 2011). the ratio is too low (<1.8) contains too much rna, while the ratio is too high (> 2.2) indicates the presence of many protein contaminants in the dna solution. dna purity of the template (dna template) greatly affects the intensity of amplified dna bands. dna molds containing compounds such as polysaccharides and phenolic compounds will result in a faint or unclear amplification dna band (sambrook et al., 1989). genetic markers (rapd) are very sensitive to reaction conditions and dna purity of the mold (young et al., 2000). conclusion isolation of rice dna of local variety of south sumatera using dna method of genomic dna purification system kit from table 2. quantification of dna ctab method no sample quantity 1 padi pegagan 1,74 2 padi dayang rindu 1,73 3 padi dayang kuning 1,92 4 padi seluang 1,72 5 padi panak/pendek 1,68 6 padi pamulan/4 bulan 1,65 7 padi talang 1,75 8 padi sanapi 1,68 9 padi ketan itam 1,66 10 padi ketan putih 1,71 11 padi ketan abang 1,67 12 padi meto tomok 1,68 13 padi dayang telasih 1,71 14 padi pengagat 1,60 15 padi hitam 1,69 16 padi putih 1,57 17 padi pulut 1,72 18 padi dayang rindu 1,67 19 padi panjang 1,76 20 padi jambat thehas 1,74 21 padi beram 1,72 22 padi stik 1,74 table 3. quatification of dna using promega no sample quantity 1 padi pegagan 1.806 2 padi dayang rindu 1.86 3 padi dayang kuning 1.839 4 padi seluang 1.889 5 padi panak/pendek 1.863 6 padi pamulan/4 bulan 1.802 7 padi talang 1,820 8 padi sanapi 1.985 9 padi ketan itam 1.828 10 padi ketan putih 1.808 11 padi ketan abang 1.804 12 padi meto tomok 1.848 13 padi dayang telasih 1,857 14 padi pengagat 1.897 15 padi hitam 1.877 16 padi putih 1.893 17 padi pulut 1.852 18 padi dayang rindu 1.815 19 padi panjang 1,881 20 padi jambat thehas 1,898 21 padi beram 1.843 22 padi stik 1.804 figure 2. result of dna band visualization wizard genomic dna purification system kit promega. figure 1. result of dna band visualization ctab method hanum et al. 2018 / science & technology indonesia 3 (1) 2017: 26-29 29 promega has higher quality and quantity compared with ctab method isolate. references arif, i.a., bakir, m.a., khan, h.a., al farhan, a.h., al homaidan, a.a., bahkali, a.h., al sadoon, m. and shobrak, m. 2010. application of rapd for molecular characterization of plant species of medicinal value from an arid environment. genet. mol. res. 9(4): 2191-9198. fatchiyah, a.e.l., widyarti, s., dan rahayu, s. 2011. biologi molekuler: prinsip dasar analisis. jakarta: erlangga xxiv + 191hlm. karmana, wayan, i. 2009 adopsi tanaman transgenik dan beberapa aspek perkembangannya. genec swara. 3(2): 12-21. pharmawati m. 2009. optimalisasi ekstraksi dna dan pcrrapd pada grevillea spp. (proteaceae). jurnal biologi, 8(1) : 12 -16. poerba, yuyu., s., martanti, d. 2008. keanekaragaman genetik berdasarkan marka random amplified polymorphic dna pada amorphophallus muelleri blume di jawa. biodiversitas. 9(4): 245-249. restu m, mukrimin, dan gusmiaty. 2012. optimalisasi teknik ekstraksi dan isolasi dna tanaman suren (toona sureni merr.) untuk analisis keragaman genetik berdasarkan random amplified polymorphic dna (rapd). jurnal natur indonesia, 14(2): 138142. sambrook, j., fritsh, e.f. and maniatis t. 1989. molecular cloning. cold spring harbor laboratory press. new york. young et., sloan js., van riper k. 2000. trinucleotide repeats are clustered in regulatory genes in saccharomyches cerevisiae. genetics. 154(3): 1053-68. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper tablet formulation with galactomannan binding agent and acute toxicity test from terminalia catappa l. nilsya febrika zebua1*, tandra alexandro1, virda widya pratiwi1, syarifah nadia1, supran hidayat1, muflihah fujiko1, muharni saputri1, tedy kurniawan bakri2, nerdy3 1department of pharmacy, tjut nyak dhien university, medan, 20123, indonesia2department of pharmacy, syiah kuala university, banda aceh, 23111, indonesia3department of pharmacy, deli husada deli tua institut, medan, 20355, indonesia *corresponding author: nf.zebua@gmail.com abstractketapang is one of the many medicinal plant species that grow in indonesia and is used to treat various diseases. ketapang leavescontain flavonoids, tannins, saponins, and terpenoids that have anti-inflammatory, antioxidant, antiviral, and antimicrobial properties.this study aimed to determine the ld50 and histopathology of liver and kidney damage before the formulation of tablets containinggalactomannan-binding agents. the toxicity determination method was carried out in vivo in experimental animals at doses of 4g/kgbw, 8g/kg bw and 16g/kg bw, and liver and kidney histopathology was carried out before formulation into tablet preparations usingthe wet granulation method with various concentrations of binders and disintegrants, namely f1(8:0), f2(0:8), f3(4:4), f4(2:6), andf5(6:2). the results of the toxicity test showed an ld50 of 15.9959, liver damage at a dose of 4 g/kg bw hepatocyte karyorrhexis cells,central vein constriction, sinusoidal dilatation, a dose of 8 g/kg bw hepatocyte karyorrhexis, significant venous congestion, sinusoidaldilatation, a dose of 16 g/kg bw hepatocyte cells, karyolysis, dilated central veins, and dilated sinusoids. the results of the tablet masspreformulation test meet the requirements: the flow time test was 1.48-2.14 g/second, the angle of repose test was 24.60°-30.60°,and the tab index test was 5.33%-9.33%. the results of the tablet evaluation test were as follows: the tablet hardness test was3.8-8.6 kg, the tablet friability test was 0.167-0.64%, and the tablet disintegration time test was 29.06-107.51 minutes. keywordsketapang leaves, toxicity, histopathology, tablets, preformulation test, tablet evaluation received: 26 august 2022, accepted: 5 january 2023 https://doi.org/10.26554/sti.2023.8.1.129-136 1. introduction excipients from natural sources have an advantage over synthetic excipients in that they are locally accessible, nonpolluting, biocompatible, and cheap as compared to imported synthetic products (pawar and geevarghese, 2013) . modifying natural polysaccharides is a new strategy for preparing environmentally friendly biomaterials. polysaccharides are excellent alternatives to synthetic compounds for the manufacture of binders. galactomannan is a polysaccharide soluble in water, nontoxic, biocompatible, and economical. galactomannan shows potential in the production field, and its application does not cause pollution; therefore, it does not disturb the ecosystem. in the pharmaceutical field, galactomannan is used as a suspending agent, emulsifier, and matrix in sustained-release tablets (cerqueira et al., 2019) . ketapang leaf is a medicinal plant that grows in indonesia and is used to treat various diseases. ketapang leaves possess anti-inflammatory, antibacterial, antioxidant, anticancer, and antidiabetic properties (hayaza et al., 2019) . however, its use in medicine is unknown due to its toxicity and safety. therefore, it is necessary to test raw materials before they are formulated in pharmaceutical dosage forms. toxicity tests detect the degree of danger in biological systems exposed to humans. doses that can cause toxic effects in humans are generally obtained from experiments using experimental animals that are carried out as supporting evidence for the safety of test preparations (bpom ri, 2020) . organs that are susceptible to damage due to toxicity are the liver and kidneys. tablets are solid dosage forms containing active substances with or without excipients (which improve the quality of tablet preparations, flow properties, and disintegration) made by compressing granules in a tablet machine (departemen kesehatan republik indonesia, 2020) . https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.129-136&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.129-136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 herbal medicines have been gaining popularity. the thick extract of ketapang leaves is formulated in an oral dosage form, namely tablets, as it is a pharmaceutical preparation with excellent stability and is easy to consume and use. based on the description above, this research intends to formulate a binder derived from galactomannan, which is formulated with variations because, in general, herbal extracts tend to be hygroscopic, affecting tablet flow properties and can affect the compatibility of tablet preparations. therefore, various binders were used to determine optimal tablet quality. in addition to testing the safety of the drug substance (terminalia catappa l.) toxicity and the liver’s histopathology, kidney damage was assessed before formulation in tablet dosage form with galactomannan binding material. 2. experimental section 2.1 materials the ketapang leaf extract ingredients used in this study consisted of dried simplicia of ketapang leaves obtained from medan helvetia, north sumatra and ethanol p.a. qualitative test materials 96% ethanol, distilled water, hydrochloric acid, ammonia, diethylether, chloroform, lead(ii) acetate, isopropanol, anhydrous sodium sulfate, methanol, anhydrous acetic acid, sulfuric acid, petroleum ether, iron(iii) chloride, benzene, ethyl acetate, magnesium, sodium hydroxide, sodium carbonate, toluene, zinc, potassium dihydrogen phosphate, bouchardart, dragendorff, and mayer. the ingredients for manufacture of the tablets included: ethanol extract of ketapang leaves, talc, mg stearate, starch, lactose, and galactomannan. toxicity test materials included: male mice (musmusculus), and na.cmc. other ingredients in this study included: an analytical balance (and®), oven (memmert®), balance (kenmaster®), rochefriabilator (erweka®), hardnest tester (erweka®), desintegration tester (erweka®), index carr’s (erweka®), tablet press (erweka®), hopper (erweka®), water bath, mortar and stamper, mesh no. 14, stopwatch, litmus paper and filter paper. 2.2 methods 2.3 preparation and extraction of ketapang leave extracts were made using the maceration method with 1000 g of p.a. ethanol as a solvent and with p.a. ethanol as a solvent. maceration was carried out for three days while the extracts were stirred several times. the contents were stirred periodically, placed inside the bottle, and shaken to ensure complete extraction. finally extraction process, the micelles were separated from the marc by filtration or decantation (abubakar and haque, 2020) . 2.3.1 phytochemical screening an alkaloid test was performed by adding hcl to the simplicia powder until the ph of the solution became acidic. it was then heated, cooled, and filtered. the filtrate obtained was divided into three tubes and drops of different reagents were added to each tube, namely mayer, bouchardart, and dragendorf. a white precipitate indicated a positive reaction in the mayer reagent, a brown residue in the bouchardart reagent, and a brown residue in the dragendorff reagent. the simplicia powder flavonoid test was conducted by adding methanol to the solution, refluxing for 30 min, and filtering. after cooling, kerosene ether was added, and two layers were formed. the bottom layer was evaporated at a temperature of 40◦c, and the residue was dissolved in 5-10 ml of ethyl acetate and filtered. the filtrate was divided into two tubes: tube one was given zn powder and 2n hcl and showed positive results if it showed an intense red colour. for tube 2, mg powder was added, and the concentrated hcl showed positive effects if a yellow to orange or a purplish red colour was formed. a simplicia powder saponin test was conducted by adding hot water and vigorously shaking the resulting solution. after shaking the solution, 2 n hcl was added, and a positive result was recorded if the foam persisted for 10 s. a simplicia powder tannin test was conducted in water, soaked for 30 min, and then filtered. the filtrate was then mixed with 5% iron (iii) chloride, a positive reaction was recorded if the mixture turned green or blue-black, samples were treated with n-hexane for 2 h and filtered for the terpenoid and steroid tests. the filtrate was evaporated and subjected to the liebermann-burchard reagent. a positive reaction was recorded if a purple or red colour was formed, indicating the presence of a free triterpenoid compound group; if a green or blue to greenish blue colour occurred, it showed the presence of a free steroidal compound group (doughari, 2012; zohra et al., 2012). 2.3.2 preparation and treatment of test animals the mice used were 16 male mice. before being given the treatment, the mice were acclimatised to the new environment over seven days and given standard feed and water ad libitum during, before, and after the experiment (bpom ri, 2020) . after the acclimatisation period, the mice were divided into four groups that were randomly selected: the negative control group, which was given standard feed and na cmc, and the treatment group f1 eedktp 4 g/kg bw, f2 eedktp 8 g/kg bw, and f3 eedktp 16 g/kg bw. each group consisted of four mice. guidelines for the care and use of laboratory animals documented by the universitas tjut nyak dien for the care and use of laboratory animals were strictly. 2.3.3 toxicity test the test was carried out according to the guidelines (bpom ri, 2020) . the ethanol extract of ketapang leaves was given orally once for a 14-day test period, and then the mice were observed for any toxic symptoms that appeared. observation times were 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 210 minutes, and 240 minutes. the total observation time was four h periodically, which continued for the first 24 h, after which they were observed for 14th days. particular attention was paid to the following areas: skin, hair, eyes, respiratory system, autonomic nervous system, central nervous system, somatomotor activity, and behaviour. on the 15th day, after 12 h of fasting, the mice were euthanised and © 2023 the authors. page 130 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 underwent surgery to remove the liver and kidneys, which were taken and stored in 10% neutral buffered formalin for histological studies (erhirhie et al., 2018; oecd, 2002). table 1. toxicity symptoms group toxic symptom limp tremor diarrhoea walk with stomach control 4 g/kg bw + 8 g/kg bw + + + 16 g/kg bw + + + + description: (+) contains compounds (-) does not contain compounds table 2. number of deaths of mice dosage of administration number of mice number of mice life death control 4 4 0 eedktp 4 0 4 g/kg bw eedktp 4 1 8 g/kg bw eedktp 2 2 16 g/kg bw table 3. tablet formulation ingredient f1 (%) f2 (%) f3 (%) f4 (%) f5 (%) eedk 40 40 40 40 40 galactomannan 8 4 2 6 starch 8 4 6 2 talkum 1 1 1 1 1 mg-stearat 1 1 1 1 1 lactose add 500 add 500 add 500 add 500 add 500 2.3.4 making galactomannan from fronds an amount of 1500 g of arenga pinnata was cleaned, mashed with a blender for 3-5 minutes with the addition of 1:10 distilled water, and stored in a refrigerator for 24 h. subsequently, a precipitate was formed using the filter. ethanol (96%) was added to the precipitate at a volume ratio of 1:1 and the precipitate was stored in a refrigerator for 24 h. the formed precipitate was filtered through a white cloth and soaked in ethanol. the residue was filtered again and dried in a desiccator (mirhosseini and amid, 2012; tamaki et al., 2010). figure 1. liver organs a)na cmc 0,5%; b)eedktp 4 g/kgbb; c)eedktp 8 g/kgbb; and d)eedktp 16 g/kgb (description: (a)hepatocytes, (b)central vein, (c)sinusoids) 2.3.5 procedure for making tablets the dried galactomannan powder was heated in a water bath, and hot water was gradually added to form a gel (mass 1). the extract was mixed with lactose until homogeneity, and the input of the disintegrant was ground to homogeneity (mass 2) by mixing mass one little by little into mass two until a paste-like mass was formed, then sieved with a mesh of 14. the resulting granules were dried at a temperature of ±50-60°c until a constant weight was achieved, and talc and mg stearate were added as lubricants. the resulting granules (figure 3) were then tested for preformulation, including the flow time test; 100 g of granules were placed in a free flow, and the flow rate of the granules (requirements <10 s) was calculated. an angleof-pose test is conducted. the angle of repose was obtained by measuring the diameter and height of the cone-shaped pile of granules (required for a grade of repose of 20°<𝜙<40°), and the tap index test was carried out with a bulk density tester. in a measuring cup, some granules are inserted up to 50 ml, then tapped 20 times, and the volume was measured (nnamani and okonkwo, 2017; lachman et al., 1994). 2.3.6 evaluation of tablets the evaluation of tablet preparations includes organoleptic properties, weight uniformity, size uniformity, hardness, friability, and disintegration time (lachman et al., 1994; eisa et al., 2022). the fragility of the tablets was determined according to the pharmacopoeia (2008) , using a friability tester. using a disintegration tester, the uniformity of weight and dis© 2023 the authors. page 131 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 integration time was determined according to the indonesian pharmacopoeia (2020). tablet hardness was measured according to united states pharmacopeia (usp) . 3. result and discussion figure 2. kidney organs a)na cmc 0,5%; b)eedktp 4 g/ kgbb; c)eedktp 8 g/kgbb; and d)eedktp 16 g/kgb (description: (a)glomerulus, (b)bowman’s capsule, (c)tubules) figure 3. granul of tablet a)formulation 1; b)formulation 2; c)formulation 3; d)formulation 4; and e)formulation 5 3.1 investigating phytochemicals results based on the phytochemical screening on the simplicia leaves of ketapang showed that they contained alkaloids, flavonoids, saponins, tannins and steroids/triterpenoids. figure 4. flow time figure 5. still angle 3.2 toxicity test based on the toxicity symptoms shown in table 1, results were obtained at a dose of 4 g/kg bw. the toxicity test after the administration revealed a few signs of toxicity. some mice experienced weakness: however, after two h, they returned to normal levels. this could be due to the fear experienced by mice when the extract was administered. at a dose of 8 g/kg bw, the mice experienced weakness, tremors, and a fast heartbeat, and the mice became lethargic and frequently fell asleep. it can be concluded that there were signs of toxicity at a dose of 8 g/kg bw. at a dose of 16 g/kg body weight, mice experienced decreased activity, weakness, tremors, diarrhoea, and a fast heart rate. mice that died experienced restless behaviour, walking to and from, and convulsions before death. all groups with toxic symptoms appeared to depend on the concentration of the test preparation used. it was discovered that the higher the concentration of the test preparation, the greater the toxic symptoms are seen in the test animal (hodgson and levi, 1987; sequeira-cordero et al., 2019; sharp et al., 2003). © 2023 the authors. page 132 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 figure 6. index tab figure 7. result tablet a)formulation 1; b)formulation 2; c)formulation 3; d)formulation 4; and e)formulation 5 3.3 observation of mortality and determination of ld50 based on the number of dead mice in table 2, the ld50 value was 15.9959, and the ketapang leaf extract was categorised as practically non-toxic. an ld50 assessment can lead to the general conclusion that the lower the ld50 value, the more toxic the substance is being tested. conversely, the higher the ld50 value is, the less likely it is to be harmful (erhirhie et al., 2018) . the phytochemical identification of the ethanol extract of ketapang leaves showed that the ethanol extract contained phytochemicals such as alkaloids, flavonoids, tannins, saponins, and steroids/triterpenoids. these metabolites are used in various pharmaceutical and cosmetic preparations. the ld50 15.9959 indicated that the ethanol extract of ketapang leaves was practically non-toxic (erhirhie et al., 2018) , indicating that these substances can be safely used in products such as drugs, nutraceuticals, and cosmeceuticals. 3.4 results of organ macro pathology examination observations of the liver and kidneys in all the groups showed no significant changes. a normal liver is a dark red colour; when pressed, it feels slightly hard and slippery. mild liver degeneration does not affect the macroscopic appearance of the liver because the liver has a high regeneration capacity. tissue damage due to toxic substances stimulates the mechanism by figure 8. hardness tablet table 4. flow time test results formulation flow time (second) avarage (second) f1 1.56 1.481.42 1.46 f2 2.17 2.142.12 2.14 f3 1.72 1.731.75 1.73 f4 1.79 1.831.83 1.87 f5 1.56 1.621.63 1.67 which liver cells begin to divide and continues until tissue mass repair is achieved. the abnormal kidney appears pale. on the surface structure of the irregular kidney nodules can be found (andayani et al., 2018; gasmi and kleiner, 2020). 3.5 hispathology results in the organs of mice histopathology of the liver organs figure 1. in the cmc na 0.5% control group, histopathological images of the liver were standard. the 4 g/kg bw eedktp treatment group experienced changes in hepatocyte karyogenesis and sinusoidal dilatation. the eedktp group of 8 g/kg bw observed karyoexic changes in hepatotic cells, central venous congestion, and sinusoidal dilatation. the 16 g/kg bw eedktp group experienced changes in hepatocyte karyolysis, major venous dilatation, and sinusoidal dilatation. necrosis is the death of cells or tissues in living organisms, and as a result, these cells © 2023 the authors. page 133 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 table 5. results of still angle formulation high (cm) diameter (cm) still angle (∅) average (∅) f1 2.0 8.0 26.60° 24.601.7 8.0 23.02° 1.8 8.0 24.22° f2 2.5 8.0 32.00° 30.602.3 8.0 29.90° 2.3 8.0 29.90° f3 1.8 8.0 24.22° 25.012.0 8.0 26.60° 1.8 8.0 24.22° f4 2.1 8.0 27.70° 27.702.0 8.0 26.60° 2.2 8.0 28.80° f5 1.8 8.0 24.22° 25.402.0 8.0 26.66° 1.9 8.0 25.40° can no longer function in taking nutrients because they have been damaged. the blackening of the tissue in histology preparations characterizes this. central vein congestion occurs because too much blood enters the arteries or too little blood enters the veins. microscopically, congestion is characterised by dilatation of the arterial wall caused by a large blood volume in the central vein. the major vein dilates if there is damage because the endothelial cells lyse. a high compound concentration in the blood causes blood distribution with muscular perfusion to be channelled into the sinusoids, which causes the sinusoids to widen. liver sinusoids function as a place for blood to flow which empties into the central vein, but some are inactive and serve as a blood reservoir (saleh et al., 2017; ta et al., 2013). results of histopathology of the kidneys organs figure 2. in the control group, the cmc na 0.5% of the kidneys were in average condition. the eedktp 4 g/kg bw, eedktp 8 g/kg bw, and eedktp 16 g/kg bw groups experienced glomerular hypertrophy and bowman’s capsule narrowing; in the 4 g/kg bw and 8 g/kg bw groups, the tubules were expected, but in the 16 g/kg bw treatment, the tubules were narrowed. kidney damage is characterised by hypertrophy, atrophy, and hyperplasia. several factors, including the entry of toxic substances, can cause kidney damage. toxic substances can cause damage to the proximal tubular epithelium, narrowing the gap between the bowman’s capsule and the renal medulla, glomerular atrophy, and hypertrophy. glomerular hypertrophy is tissue damage characterised by an increase in organ size due to an increase in the size of glomerular cells, which separates cells from one another. glomerular hypertrotable 6. index tab test results formulation pre volume (ml) post volume (ml) indeks tap (%) average (%) f1 50 47 6 5.3350 47 6 50 48 4 f2 50 45 10 9.3350 45 10 50 46 8 f3 50 46 8 7.3350 46 8 50 47 6 f4 50 45 10 8.6750 46 8 50 46 8 f5 50 47 6 6.6750 47 6 50 46 8 phy is an early detection marker of kidney damage (aslan et al., 2018; ibrahim et al., 2018; ho kim et al., 2014). 3.6 formulation design the design of the tablet formulas using galactomannan binders resulted in five formulas, as shown in figure 7 and table 3. ketapang leaf extract tablets were prepared by the wet granulation method because of the consideration of extract characteristics, such as viscosity, hygroscopicity, flow properties, and powder comparability, so that the powder was easily compressed into tablet preparations. the quality of all formulas can be determined from preformulation tests that meet the requirements. the pre-formulation test results are presented in figures 4, 5, 6, and tables 4, 5, 6 (priya and asuntha, 2022) . in general, extracts tend to be more hygroscopic and have lower solubility. therefore, good flow properties are the main specifications for achieving weight uniformity during tablet compression. 3.7 fiscal properties tablets friability has been tested to assess the effect of shocks or shocks that often cause tablets to break or crack (hoa et al., 2018) . according to lachman et al. (1994), a good value of 0.8% because of the lack of brittleness of the tablet indicates that the tablet has shock resistance that can maintain its shape. based on figure 9, formula 1 has a friability of 0.167%; formula 2 has a friability of 0.64%; and formulas 3, 4, and 5 have friabilities of 0.37%, 0.49%, and 0.19%, respectively. the fifth formula indicates that all the formulas satisfy the requirements. subsequently, tablets were tested to assess their mechanical resistance during packaging and distribution. the varied galactomannan and starch components significantly increased the hardness and © 2023 the authors. page 134 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 figure 9. friabilitation figure 10. disintegration slowed the disintegration time (lachman et al., 1994) . figure 8 shows that the tablet hardness values in formula 1 ranged from 8-10 kg, whereas in formula 2, the tablet hardness ranged from 3-4 kg, in formulas 3,4 and 5 went from 4-6 kg, 4-6 kg, and 6-9 kg, from the 5th formula only formulas 3 and 4 are eligible. the disintegration time was tested to assess the time taken by the tablet to break down and release the active substance. based on figure 10, it can be seen that the time needed in formula 1 is 105-109 minutes; in formula 2, the time required is 28-29 minutes; in formulas 3, 4 and 5, the time required is 78-80 minutes, 45-49 minutes, and 100-102 minutes. of the five formulas tested, they did not test formulas that meet the requirements of the indonesian pharmacopoeia in 2020. the disintegration time for ordinary tablets was less than 15 min. for tablets, the increase was not more than 60 min. 4. conclusion toxicity testing of the liver and kidney revealed damage and symptoms in mice. ketapang leaf extract tablets met the requirements, variations in the concentration of binders and disintegrants significantly affect the physical properties of tablets, especially on the hardness and disintegration time; the higher the concentration of binders used, the more complex the tablets and the longer the disintegration time. 5. acknowledgment the authors thank the faculty of the pharmacy department of tjuk nyak dhien university for providing facilities to implement this research. references abubakar, a. r. and m. haque (2020). preparation of medicinal plants: basic extraction and fractionation procedures for experimental purposes. journal of pharmacy & bioallied sciences, 12(1); 1–5 andayani, n. k. p. s., i. setyawati, and m. joni (2018). kidney histopathology of gallus gallus domesticus infected by e. coli in denpasar, bali. advances in tropical biodiversity and environmental sciences, 2(1); 14–17 aslan, a., m. c. van den heuvel, c. a. stegeman, e. r. popa, a. m. leliveld, g. molema, j. g. zijlstra, j. moser, and m. van meurs (2018). kidney histopathology in lethal human sepsis. critical care, 22(1); 1–12 bpom ri (2020). peraturan badan pengawas obat dan makanan tentang pedoman uji toksisitas praklinik secara in vivo. journal of chemical information and modeling, 53(9); 21–25 (in indonesia) cerqueira, m. a., a. c. pinheiro, l. m. pastrana, and a. a. vicente (2019). amphiphilic modified galactomannan as a novel potential carrier for hydrophobic compounds. frontiers in sustainable food systems, 3; 17 departemen kesehatan republik indonesia (2020). farmakope indonesia edisi vi. jakarta: direktorat jendral bina kefarmasian dan alat kesehatan republik indonesia (in indonesia) doughari, j. h. (2012). phytochemicals: extraction methods, basic structures and mode of action as potential chemotherapeutic agents. intech open access publisher rijeka, croatia eisa, a. m., n. a. el-megrab, and h. m. el-nahas (2022). formulation and evaluation of fast dissolving tablets of haloperidol solid dispersion. saudi pharmaceutical journal, 30(11); 1589–1602 erhirhie, e. o., c. p. ihekwereme, and e. e. ilodigwe (2018). advances in acute toxicity testing: strengths, weaknesses and regulatory acceptance. interdisciplinary toxicology, 11(1); 5–12 gasmi, b. and d. e. kleiner (2020). liver histology: diagnostic and prognostic features. clinics in liver disease, 24(1); 61–74 hayaza, s., s. istiqomah, r. j. k. susilo, b. inayatillah, a. n. m. ansori, d. winarni, s. a. husen, and w. darmanto (2019). antidiabetic activity of ketapang (terminalia catappa l.) leaves extract in streptozotocin-induced diabetic mice. indian veterinary journal, 96(12); 11–13 © 2023 the authors. page 135 of 136 zebua et. al. science and technology indonesia, 8 (2023) 129-136 ho kim, c., b. jin lim, y. sung bae, y. eun kwon, y. ly kim, k. heon nam, k. sook park, s. yeong an, h. mo koo, and f. mee doh (2014). using the oxford classification of iga nephropathy to predict long-term outcomes of henoch– schönlein purpura nephritis in adults. modern pathology, 27(7); 972–982 hoa, v. t., b. huong, and n. d. h. do quang duong (2018). cause-effect relations and optimization of tablet containing eucommia ulmoides and gardenia jasminoides spraydried extracts. international journal of pharmacy and pharmaceutical sciences,, 10(7); 33 hodgson, e. and p. e. levi (1987). a textbook of modern toxicology, volume 274. elsevier new york ibrahim, k. e., m. g. al-mutary, a. o. bakhiet, and h. a. khan (2018). histopathology of the liver, kidney, and spleen of mice exposed to gold nanoparticles. molecules, 23(8); 1848 lachman, l., h. a. lieberman, and j. l. kanig (1994). teori dan praktek farmasi industri edisi iii. jakarta: penerbit universitas andalas mirhosseini, h. and b. t. amid (2012). a review study on chemical composition and molecular structure of newly plant gum exudates and seed gums. food research international, 46(1); 387–398 nnamani, n. d. and t. j. okonkwo (2017). optimization of metronidazole tablet formulation using manihot utilissima starch and a combination of processing techniques. future journal of pharmaceutical sciences, 3(1); 65–70 oecd (2002). test no. 423: acute oral toxicity-acute toxic class method. oecd publishing pawar, h. and r. geevarghese (2013). development and evaluation of mucoadhesive patch using a natural polysaccharide isolated from cordia dichotoma fruit. journal of molecular pharmaceutics & organic process research, 02(03); 91–98 pharmacopoeia, b. (2008). british pharmacopoeia volume 1 & 2. london: the british pharmacopoeia commission priya, n. l. and g. asuntha (2022). formulation and evaluation of sitagliptin liposomes. world journal of pharmaceutical sciences; 191–207 saleh, r., b. h. merghani, and w. awadin (2017). effect of high fructose administration on histopathology of kidney, heart and aorta of rats. journal of advanced veterinary and animal research, 4(1); 71–79 sequeira-cordero, a., a. salas-bastos, j. fornaguera, and j. brenes (2019). behavioural characterisation of chronic unpredictable stress based on ethologically relevant paradigms in rats. scientific reports, 9(1); 1–21 sharp, j., t. zammit, t. azar, and d. lawson (2003). stresslike responses to common procedures in individually and group-housed female rats. journal of the american association for laboratory animal science, 42(1); 9–18 ta, w., a. chawla, and j. pollard (2013). origins and hallmarks of macrophages: development, homeostasis, and disease. nature, 496(7446); 445–455 tamaki, y., t. teruya, and m. tako (2010). the chemical structure of galactomannan isolated from seeds of delonix regia. bioscience, biotechnology, and biochemistry, 74(5); 1110–1112 united states pharmacopeia (usp) convention (2009). united states pharmacopeia (usp) national formulary 40 nf-35 zohra, s. f., b. meriem, s. samira, and m. muneer (2012). phytochemical screening and identification of some compounds from mallow. journal of natural product and plant resources, 2(4); 512–516 © 2023 the authors. page 136 of 136 introduction experimental section materials methods preparation and extraction of ketapang leave phytochemical screening preparation and treatment of test animals toxicity test making galactomannan from fronds procedure for making tablets evaluation of tablets result and discussion investigating phytochemicals toxicity test observation of mortality and determination of ld50 results of organ macro pathology examination hispathology results in the organs of mice formulation design fiscal properties tablets conclusion acknowledgment science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2016) 25-28 article http://sciencetechindonesia.com @2016 published under the terms of the cc by nc sa 4.0 license 25 keggin type polyoxometalate h4[αsiw12o40].nh2o as intercalant for hydrotalcite neza rahayu palapa1,*, muhammad said1 1department of chemistry, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail: nezarahayu@gmail.com abstract the synthesis of hydrotalcite and polyoxometalate h4[αsiw12o40].nh2o with the ratio (2:1), (1:1), (1:2) and (1:3) has been done. the product of intercalation was characterized using ft-ir spectrophotometer, xrd, and tg-dta. polyoxometalate h4[αsiw12o40].nh2o intercalated layered double hydroxide was optimised to use as adsorbent congo red dye. characterization using ft-ir was not showing the optimal insertion process. the result using xrd characterization was showed successful of polyoxometalate h4[αsiw12o40].nh2o inserted layered double hydroxide with a ratio (1:1) which the basal spacing was expanded from 7,8 ȧ to 9,81 ȧ. furthermore, the thermal analysis was performed using tg-dta. the result show that the decomposition of polyoxometalate h4[αsiw12o40].nh2o intercalated hydrotalcite with ratio (1:1) was occured at 80oc to 400oc with a loss of oh in the layer at 150oc to 220oc, and then the decomposition of the compound polyoxometalate h4[αsiw12o40].nh2o at 350oc to 420oc. keywords: hydrotalcite, layered double hydroxide, polyoxometalate, intercalation introduction the layered material based on its existence is divided into layered material found in nature and synthesized. hydrotalcite is a class of synthetic anionic clays whose represented by the general formula [m2+(1-x)m3+x(oh)2](an-)x/n•nh2o with the identities of m2+ and m3+ are divalent and trivalent metal cation and an is interlayer anion (zhao et al, 2011). hydrotalcite is modified to aim the increasing the interlayer so that it can be more effectively used. hydrotalcite modification was done by intercalation anion macro. the macro anion used is polyoxometalate keggin type, i.e. h4[αsiw12o40].nh2o. hydrotalcite intercalation by polyoxometalate used ion exchanged method. the anion macro intercalated in the hydrotalcite causes the loss of the ohand was located on the interlayer so it can be expected to increase the distance between the layers of the hydrotalcite. in this research, synthesis and characterization of hydrotalcite, polyoxometalate h4[α-siw12o40].nh2o and hydrotalcite intercalated by polyoxometalte h4[αsiw12o40].nh2o to know the functional group and the success of intercalation process used fourier characterization transform infra red (ft-ir), x-ray diffractometer (xrd) and thermo gravimetric-differential thermal analysis (tgdta). experimental section materials the chemicals used are qualified materials such as sodium metasilica, sodium tungstate, hydrochoric acid, pottasium hydroxide, pottasium chloride, diethyl ether, sodium hydroxide, sodium carbonate, magnesium nitrate and aquadest. article history submitted: 29 march 2016 accepted: 24 april 2016 doi: 10.26554/sti.2016.1.1.25-28 methods synthesis hydrotalcite hydrotalcite was synthesized in a solution with a concentration of 50 ml of mg(no3)2 1m and 20 ml of al(no3)3 1m wa s added by rapidly stirring into 250 ml of distilled water at ph value 10 of 5 ml of naoh 2m at teazmperature 40 ̊c. the reaction was maintained at a ph value of 10 then simultaneously added 20 ml of na2co3 2m and 10 ml of naoh 2m. the product obtained is white suspension and is still stirred for 3 hours at 40 ̊c and left at 70 ̊c for 40 hours. the obtained product is filtered, washed with aqua dest and dried at room temperature. the structure, term stability and product texture of hydrotalcite were characterized by ft-ir spectrophotometer, xrd, and tg-dta. polyoxometalat h4[α-siw12o40]•nh2o polyoxometalat h4[α-siw12o40]•nh2o was synthesized by dissolving methanolic sodium as much 2,75 grams into 25 ml of aqua dest was used as solution a. 45,5 grams of sodium tungstate dissolve into 75 ml of boiled aqua dest and this solution becomes b solution. 41,25 ml of hcl 4m was added slowly for 5 minutes with strong stirring to dissolve the precipitate of tungstic acid. then, solution a was added rapidly into solution b with an addition of 12,5 ml of hcl 4m. the solution was kept for an hour at 100 ̊c at ph value of 5 to 6. 12.5 ml of sodium tungstate and 20 ml of hcl 4m are added to the solution rapidly. this solution is filtrated after cooling at room temperature. the solution is used to obtain a salt or α[siw12o40]4acid. potassium salt was obtained by adjusting the solution to a ph value of 2 using a kcl of 12.5 grams rapidly to obtain a white sediment from potassium salt to form k4[αsiw12o40]. to obtain h4[α-siw13o40] polyoxometalate acid by extraction of a white sediment from potassium salt to form k4[α-siw12o40] using 20 ml diethyl ether and 30 ml of diethyl ether and concentrated hydrochloric acid (1: 1) which had mailto:nezarahayu@gmail.com palapa et al. / science and technology indonesia 1(1) 2016:25-28 @2016 published under the terms of the cc by nc sa 4.0 license 26 previously been cooled to temperature 0 ̊c. the bottom layer is taken and concentrated to obtain white crystals which are recrystallized using quads so as to obtain polyoxometalate acid h4[α-siw12o40]•nh2o. the characteristic of h4[α-siw13o40] was performed using ft-ir spectroscopy and xr analysis. preparation of hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o intercalated hydrotalcite by polyoxometalate h4[αsiw13o40] used ion exchanged method with weight variation ratio of each hydrotalcite : polyoxometalate (2:1), (1:1), (1:2) and (1:3) is by preparing a solution of 1 grams polyoxometalate h4[α-siw13o40] 1 m distilled with 50 ml of aqua dest and 1 grams hydrotalcite was added to 25 ml of naoh 1m.. solution a and solution b were mixed rapidly under conditions of n2 gas sterilized for 24 hours. the suspension is cooled and the product is washed with water and dried at room temperature. the structural analysis and the thermal stability of intercalated product are identifed using xrd, ft-ir, and tg-dta. results and discussion characterization of hydrotalcite and polyoxometalate h4[α-siw12o40]•nh2o and the result using ft-ir spectrophotometer the ft-ir spectrum of hydrotalcite is presented in figure 1a. it is seen that the widespread vibration peak between the wave number 3800-3300 cm-1 is the vibration of the oh group within the hydrotalcite structure. the presence of a detected peak at the 1635 cm-1 is a bending oh vibration. in the wave number 1381 cm-1, there is a vibration which is an asymmetrical stretch of nitrate and a nitrate bend at wave number 671 cm-1. vibration al-o and mg-o are at wave numbers 601 cm-1 dan 408 cm-1 (handayani, et al.2014) polyoxometalate h4[α-siw12o40]•nh2o has the vibration at 3448 cm-1. in figure 1b, identifies the presence of h2o contained in the polyoxometalate h4[αsiw12o4t0].nh2o. characteristic of polyoxometalate h4[αsiw12o40].nh2o has shown in the wave number 925 cm-1 for si-o vibration and wave number 794 cm-1 for w-o-w vibration. hydrotalcite intercalated by polyoxometalate h4[αsiw12o40].nh2o ratio 2:1; 1:1; 1:2; and 1:3 is presented in fig. 1c, d, e, and f. hydrotalcite intercalated by polyoxometalate h4[α-siw12o40].nh2o ratio 2:1; 1:1; and 1:2 did not show the characteristic of polyoxometalate h4[α-siw12o40].nh2o wherein 3 peaks at wave number 980-770 cm-1, but only the widespread nitrate bending of wavenumber 820-550 cm-1 was shown. as for hydrotalcite intercalated by polyoxometalate ratio 1:3, the ft-ir spectra shown the vibration at wavenumber 833 cm-1 indicated the presence of polyoxometalate h4[αsiw12o40].nh2o and then more identified using x-ray diffraction. characterization of hydrotalcite and polyoxometalate h4[αsiw12o40]•nh2o and the intercalation result using x-ray difraction polyoxometalate h4[α-siw12o40].nh2o was characterized using xrd. the pattern is shown in fig. 2. polyoxometalate h4[α-siw12o40]•nh2o has a diffraction at 2θ is 8, 9, 18 and 27o. distractions for polyoxometalate is generally present at 6-10°, 15-20°, 22-25° and 35-40° (yang et al, 2011). hydrotalcite and hydrotalcite intercalated by polyoxometalate are shown in fig 3. hydrotalcite pattern of xrd has shown the layered structure is located at the diffraction at 2θ is 11o intensity 106 and the basal spacing is 7,4 ȧ and the peak in the diffraction pattern 2θ of 60o indicates that the presence of anions on the interlayer (dolidovich and palkovits, 2015). figure 1. ft-ir spectra a) hydrotalcite, b) polyoxometalate h4[αsiw12o40]•nh2o, c) hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o 2:1, d) 1:1, e) 1:2 dan f) 1:3. figure 2. pattern of polyoxometalat h4[αsiw12o40]•nh2o hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o with ratio 2:1; 1:1; 1:2; and 1:3 have been characterized and the result is shown in fig 3. the diffraction at 2θ is 11,2o intensity 265 and basal spacing 7,87 ȧ. the presence of a new diffraction peak occurring in the region of 22.9o denotes the typical peak of polyoxometalate h4[αsiw12o40].nh2o intensity 116 and basal spacing 3,8 ȧ is shown fig 3a. in addition, fig 3b has explained the highest diffraction at 2θ is 10,8̊, intensity is 342 and basal spacing is 9,81 ȧ, and diffraction at 22,5̊ which is the diffraction peak of a polyoxometalate intensity 141 and basal spacing 3,6 ȧ. fig 3c and 3d were showing the same diffraction as hydrotalcite. this palapa et al. / science and technology indonesia 1(1) 2016:25-28 @2016 published under the terms of the cc by nc sa 4.0 license 27 condition shows that hydrotalcite intercalated by polyoxometalate h4[αsiw12o40].nh2o ratio 1:1 more better than others because this ratio has the better diffraction and the highest basal spacing which shown polyoxometalate h4[αsiw12o40].nh2o has intercalated into hydrotalcite and caused increased the basal spacing. figure 3. xrd pattern a) hydrotalcite, , b) hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o 2:1, c) 1:1, d) 1:2 dan e) 1:3. characterization of hydrotalcite and hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o usi ng tg-dta hydrotalcite and hydrotalcite intercalated by polyoxometalate h4[α-siw12o40]•nh2o has characterized using tg-dta analysis by program temperature starting from 25oc to 950oc using n2 gas yielding thermogram pattern as presented in figure 4 and figure 5 . figure 4. thermogram of hydrotalcite figure 4 shows that the hydrotalcite decomposes with the loss of water molecules with an endothermic peak at temperatures of 50-100°c with a mass loss of 23%. (xie, 2006). at temperature 200-320oc has showing decomposes ohof hydrotalcite at interlayer was marked widening endothermic peak along loss the carbon dioxide at temperature 270-330 oc a total lost mass is 15,21%. the results of this tg-dta measurements show similarities with the research conducted by frost et al (2005) which shows the loss of oh groups in the interlayer layer along with the loss of co2 at temperature 300400oc. at temperature 650-770oc, there is a decomposition of hydrotalcite in the presence of an endothermic peak marked by loss of carbonate anion attached to chemically bonded mg2+ and al3+ is 22,89 % (lin et al, 2001). figure 5 shows the decomposition at temperature 150220oc with the loss oh in interlayer (zhang et al, 2012). according to khozhevnikov (2002), thermogram pattern has shown decomposition at 350-420oc is decomposition of polyoxometalate h4[α-siw12o40]•nh2o with the loss hydrogen bonding of polyoxometalate h4[α-siw12o40]•nh2o of ion hydroxide. figure 5. thermogram hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o ratio (1:1). conclusion hydrotalcite has been successfully intercalated by polyoxometalate h4[αsiw12o40]•nh2o ratio of mass hydrotalcite: polyoxometalate h4[αsiw12o40]•nh2o which optimum is ratio 1:1. hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o, with mass ratio 1:1 has characterization using ft-ir spectrophotometer, xrd, and tg-dta. the result of ft-ir spectrophotometer have not shown the optimal intercalated process, characterization of xrd was shown that the diffraction at 2θ is 10,8̊ with intensity 342 dan basal spacing is 9,81 ȧ, and diffraction at 22,5̊ is characterized of polyoxometalate h4[αsiw12o40]•nh2o. the thermal analysis was carried out using tg-dta into hydrotalcite intercalated by polyoxometalate h4[αsiw12o40]•nh2o was decomposition at 80oc until 400oc with loss oh in interlayer at 150-220oc while for decomposition of polyoxometalate h4[αsiw12o40]•nh2o at temperature 350-420oc. 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hydroxide: oximation of aromatic aldehydes. green chem. 13: 384-388 zhang, y., su, j., pan, q., and qu, w., 2012. polyoxometalate intercalated mgal layered double hydroxide and its photocatalytic performance. journal of materials science and engineering. 2(1): 59-63. zvezdova, dilyana., 2014. preparation, characterization and adsorption properties of chitosan nanoparticles for congored as a model anionic direct dye. naccni trudove na rusendev university. 53(10): 83-8 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 2, april 2022 research paper tritirachium oryzae and other endophytic mediated jambu bol (syzygium malaccense) are potential as an antioxidant yustina hapida1,2, elfita3*, hary widjajanti4, salni4 1graduate school of sciences, faculty of mathematics and natural sciences, university of sriwijaya, palembang, 30139, indonesia2universitas islam negeri raden fatah, palembang, 30126, indonesia3department of chemistry, faculty of mathematics and natural sciences, university of sriwijaya, palembang, 30862, indonesia4department of biology, faculty of mathematics and natural sciences, university of sriwijaya, palembang, 30862, indonesia *corresponding author: elfita69@gmail.com abstractnatural bioactive substances have been discovered produced of intracellular fungi. intracellular fungi, as well as endophytic fungi, itcan be found in organs are leaves, stems, roots, fruits, flowers, and seeds. this study aimed to specify for antioxidant activity ofintracellular fungi jambu bol (syzygium malaccense) mediated and identify secondary metabolites compounds. the liquid culture waspartitioned with ethyl acetate solvent. using chromatographic techniques, extracts were separated from their secondary metaboliteswith antioxidant activity apply the dpph procedure. its chemical structure was determined using nmr spectroscopic research, andendophytic fungi were recognized using phenotypic characteristics and molecular classification. the endophytic fungus isolationyielded four isolates: yf11, yf12, yf13, and yf14. yf12, with an ic50 of 53.03 g/ml, was the fungus that exhibited good antioxidantactivity. pure chemical secondary metabolites compounds were identified as 2-(4-hydroxyphenyl)-4-methoxytetrahydrofuran-3-ol. tritirachium oryzae was identified as the endophytic fungus yf12 based on morphological studies and a phylogenetic tree. to boostits antioxidant activity, more study is needed to perform a semi-synthetic reaction on this pure molecule. keywordsantioxidant, tritirachium oryzae, syzygium malaccense, endophytic fungi received: 8 december 2021, accepted: 29 march 2022 https://doi.org/10.26554/sti.2022.7.2.220-227 1. introduction the production of reactive oxygen species known as free radicals often occurs in all cells as part of normal metabolic processes (goart et al., 2021; phaniendra et al., 2015). free radicals have been implicated in the pathogenesis of many chronic diseases such as cancer, hypertension, and diabetes (liguori et al., 2018). an antioxidant is needed to inhibit cell damage (forrester et al., 2018). the use of synthetic antioxidants in inhibiting the activity of free radicals in damaging body cells can cause toxic side eects. therefore, the search for natural antioxidants is very necessary (ibrahim et al., 2021). endophytic fungi live in the internal tissues of all plant species without causing disease symptoms in their hosts (nair and padmavathy, 2014). these endophytic fungi can synthesize bioactive compounds that have proven useful for the process of new drug discovery. the production of bioactive secondary metabolites from endophytic fungi has become a focus of research in recent decades because endophytic fungi represent interesting microorganisms to explore due to their diverse biotechnological potential (girón et al., 2021). plants with ethnographic backgrounds for the treatment of various diseases are promising candidates for obtaining bioactive compounds from their endogenous fungi. jambu bol (s. malaccense) is found in southern sumatra, indonesia as herbal medicine in treating diseases such as hypertension, diabetes, and diarrhea. the results of a literary study, jambu bol plants have been used as traditional medicine by humans in various parts of the world. in brazil, it is used to treat diabetes (freitas et al., 2015). in india and nigeria, the fruit, seeds, and bark are used in treating dysentery, diabetes, gastric ulcers, antiinammatory, and antimicrobial (bairy et al., 2005; oyinlade, 2014). endophytic fungus isolated from medicinal plants as an antioxidant, syzygium aqueum has been reported to create secondary metabolites (habisukan et al., 2022). root bark, stem bark, and leaves of s. malaccense have been identied as endophytic fungus with antibacterial activity (hapida et al., 2021). in this paper, we report the endophytic fungi that live in the fruit tissue of s. malaccense, their antioxidant activity, and the secondary metabolites contained in the active extract of the https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.2.220-227&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.2.220-227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 endophytic fungus. 2. experimental section 2.1 materials this study used pda and pdb fungal growth media (merck), alcohol 70%, aqua dm, sodium hypochlorite (naocl), dpph (sigma alderich), organic solvents like ethyl acetate, n-hexane, chloroform, tlc silica gel, and chloramphenicol antibiotic. 2.2 plant material the organs used in this study were fresh and healthy fruit from jambu bol (s. malaccense) obtained in palembang city, south sumatra. the taxonomic examination of the jambu bol (s. malaccense) plant was carried out in the laboratory of the lipi botanical garden purwodadi. with number: b-302/iii/ks. march 1, 2021. 2.3 isolation of endophytic fungi endophytic fungi to be isolated from fresh fruit washed under running water, and surface sterilized by soaking in 70% alcohol for ±180 seconds. after that rinsed with aseptic aqua dm in ±1 minute, then soaked with 3% sodium hypochlorite (naocl) for 60seconds, sodiumhypochlorite (naocl) for60seconds. the esh of the fruit used is cut aseptically. then the samples were plated inpetridishescontainingpdamedia, incubatedat room temperature for 3-14 days. morphological observations on dierent colonies, then purication was carried out (habisukan et al., 2021a). 2.4 cultivation and extraction selected endophytic fungi were cultured on pdb (potato dextrose broth) media. a total of (±106 spores/ml) of pure culture was inoculated as much as 10% (v/v) in 50 ml, in a 1-liter bottle containing 250 ml of pdb medium. the fungi were then incubated for 3-4 weeks at 27◦c (room temperature). the culture was ltered to lose from the mycelia. the liquid broth is composed and extracted with ethyl acetate, then shaken for 1 hour. the fungal extract was evaporated using an evaporator (rumidatul et al., 2021; syarifah et al., 2021). 2.5 antioxidant activity test in methanol, a 0.05 mm dpph solution was prepared. the standard liquid was made by dissolving the sample in 1000 g/ml dimethyl sulfoxide (dmso). diluting the reference liquid resulted in variations in sample concentration. 3.8 ml of 0.05 mm dpph solution was added to 0.2 ml of various amounts of sample. the solution combination agreed and stored in an invisible place for 180 seconds to avoid oxidation and protect it from sunlight. a uv-vis spectrophotometer was used to detect absorption at a _max of 517 nm. ascorbic acid was used as a positive control and the same procedure was administered as a sample. the dpph radical absorption barrier strength, namely percentage of inhibition and ic50 value was used to calculate antioxidant activity (elta et al., 2021). %inhibition = control absorbance − sample absorbace control absorbance x100% 2.6 morphological and molecular identication of endophytic fungi endophytic fungi thathavebeenpuried, identiedeachcolony based on the character formed, isolate fungi based on three main characteristics of the fungus, color and reverse colony characteristics, microscopic characteristics, and macroscopic characteristics. thenthegroupwasdened(huangetal.,2012; nguyen et al., 2021). endophytic isolates were identied using the method proposed by metasari et al. (2020), which involves comparing the similarity of sample sequences to a web-based database known as blast (basic local alignment search tool). 2.7 measurement of product acidity yf12 endophytic fungi ethyl acetate extract sample (2 g) was preabsorbed with silica gel (70-230 mesh) in a ratio of 1:1. the samples were separated by column chromatography with the eluent system gradient n-hexane–ethyl acetate (10:0–0:10) and ethyl acetate–methanol (9:1–5:5). the eluent was collected every 10 ml in the vials and tlc analysis was performed on each vial to classify column fractions. the column fraction which shows the presence of a purple major stain is then continued with column rechromatography until a pure compound is obtained. the chemical structure of the pure compound was analyzed based on nmr 1 and 2d spectroscopic data (habisukan et al., 2021b). 3. results and discussion 3.1 endophytic fungi of the fruit of s. malaccense the results of the isolation of the endophytic fungus s. malaccense obtained four isolates with codes yf11, yf12, yf13, and yf14 (figure 1). fungal identication was carried out based on the main characteristics of the fungus, namely macroscopic, microscopic, and another specic character. the success of identication and observation is inuenced by the ability to observe individual morphology, or the technical ability to induce sporulation in agar cultures. the results of this identication were compared with the literature and the key fungal determination (ueda et al., 2010). 3.2 morphological identication of endophytic fungi thefourendophytic fungi isolated froms.malaccense fruitwere identied macroscopically with the following criteria: colony color, colony texture, topography, colony pattern, exudate drops, radial line, and concentric circle. microscopic identication based on criteria: spore type, spore form, hyphae, and other specic criteria. after observing the endophytic fungal isolate colonies, then microscopic observations were made on each colony. the characteristics of each isolate are based on microscopic observations shown in tables 1 and 2. from the results of the identication of macroscopic and microscopic morphology, it was found that isolates from this © 2022 the authors. page 221 of 227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 table 1. macroscopic characteristics of endophytic fungal isolates from s. malaccense fruit code colony complexion inverse colony type colony model elevation exudate drop radial line concentric circle yf11 white yellowishwhite velvety zonate flat √ yf12 white white and pink central cottony zonate umbonate √ √ yf13 white white, spreading cottony zonate umbonate √ √ yf14 grayish white cream cottony zonate umbonate √ √ table 2. microscopic characteristics of endophytic fungi isolates from s. malaccense fruit code name spore spore form hyphae in character genus / species yf11 conidia ellipsoidal septate, aerial conidiophores hyalin, simple, bearing spore masses on phialides at the apex: phialide verticillate gliocladium sp yf12 conidia ovoid conidiofor non septate conidiophores upright, long, slender, simple, conidiogenous branches tapering to a rachislike, zigzag, fertile portion; conidia (sympodulo spores) apical on new growing points, hyaline, l-celled, globose or ovoid, saprophytic, conidiophores hyaline; conidia ovoid tritirachium sp yf13 zygospore spora septate, aerial sporangiophores erect, branching sympodial, bearing terminal sporangia, rhizoids. terminal sporangia, black, ovate mucor sp yf14 sporangiofor spora septate sporangiophores, unbranched. rhizoids the sporangiophores are terminate with a dark, round sporangium (40–275 mm in diameter) containing a columella and many oval, colorless or brown rizopus sp figure 1. four isolates of endophytic fungi from s. malaccense fruit yf11 (gliocladium sp), yf12 (tritirachium sp), yf13 (mucor sp), yf14 (rhizopus sp) and microscopic observations fruit belonged to the ascomycota group, namely yf11 and yf12. yf13 and yf14 isolates belong to the basidiomycota group. isolation of endophytic fungi that have been carried out, it was found that the number of fungi that could be isolated on the fruit of jambu bol (s. malaccense) had little and tended not to variety, this is presumably because this endophytic fungus is unique, presence is inuenced by place, tissue, environment, and plant ecology. the tissue in the fruit has a smaller amount of tissue compared to the leaves, in the fruit, there is also a phenolic contentdissolved in it. tissues inplant organsprovide dierentmicro-habitats forfungalcoloniesandtissuespecicity provides dierent substrates for the survival of endophytic fungal colonies to give rise to dominant taxa (huang et al., 2012; nguyen et al., 2021). 3.3 antioxidant activity of endophytic fungi the ethyl acetate extract of endophytic fungi from s. malaccense has been tested for antioxidant activity using the dpph method as shown in table 3. based on its ic50 value, an extract’s antioxidant activity can be classied as high (ic50 <100 © 2022 the authors. page 222 of 227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 g/ml), moderate (ic50 100-500 g/ml), or weak (ic50 5001000 g/ml) and inactive (ic50 >1000 g/ml) (mbekou et al., 2021; metasari et al., 2020). only two extracts, the endophytic fungi extract yf12 (ic50 381.04±24.54 g/ml) and the endophytic fungi extract yf14 (ic50 482.83±64.85 g/ml), showed moderate antioxidant activity. two endophytic fungus extracts, yf11 (ic50 2822.77±442.16 g/ml) and yf13 (ic50 1235.71±144.23 g/ml), were found to be in active as antioxidants. rhizopus sp, isolates from the stems of the toona sinensis plant, fungus yf14 a member of the rhizopus sp. species, was shown to exhibit substantial (moderate) antioxidant activity such as tannins (rahmawati et al., 2016). endophytic fungi extracts that have no antioxidant activity, such as isolates yf11 (gliocladium sp) and yf13 (mucor sp). the fungus glocladium sp has been isolated from canna indica showing high phenolic content but weak antioxidant activity (eskandarighadikolaii et al., 2015). from the fungus gliocladium sp, compounds ergosterol-5,8-peroxide and allitol were found which can inhibit the activity of mycobacterium tuberculosis (uc-cachón et al., 2019). table 3. antioxidant activity of s. malaccense endophytic fungi was using the dpph method, with ascorbic acid as the antioxidant standard sample genus/species of identication antioxidant activity ic50 (`g/ml) yf11 gliocladium sp 2822.77±442.16 yf12 tritirachium sp 381.04±24.54 yf13 mucor sp 1235.71±144.23 yf14 rhizopus sp 482.83±64.85 compound 1 (isolated from yf12) 53.03±0.23 ascorbic acid 16.03±0.96 species in the genus mucor sp that have been reported are mucor racemosus, and mucor circinelloides. ethyl acetate extract of the endophytic fungus mucorracemosus isolated from hibiscus sabdaria was reported to contain no avonoids in its secondary metabolites (khalil etal.,2020). however, theethanolicextract of mucor circinelloides fungi can bind phenolic compounds, tannins and avonoids under nutritional stress conditions in the late exponential phase so it can be developed as nutraceuticals and natural antioxidants (hameed et al., 2017). 3.4 molecular identication of selected endophytic fungi the yf12 endophytic fungus has been chosen to proceed to the molecular identication stage and secondary metabolite isolation because it has a good ic50 value among the four other endophytic fungal isolates. the results of molecular data analysis of yf12 isolate using mega 11, with the neighborjoining method, bootstrap consensus tree with 1000 replications, the evolutionary distance was calculated using the pdistance method to obtain a phylogenetic tree (figure 2b). the results of a phylogenetic search using the gene bank, it was found that the yf12 isolate was a species of tritirachium oryzae. the results of the nitrogen base examination and the phylogenetic tree yf12 isolate can be seen in figure 2. the its rdna sequence of the yf12 isolate is shown as follows: tcactaatgatccttccgtaggtgaacctgcgga aggatcattagtgaatttaaaaaatacagaattggat tgaaaaaaatccaaattcttatttctttattcttctc ttccactgtgaaattttaaactattcgggcggtctt ttggccggtcgaggtttagagatgggactgagtga aaaaaaattgttggggagtgcctccactttcaagtg gagcggacgatctgcagttttagttcttctgttctc tgatctagccgaattacccaatttttagagacaatgt taaatttgaatgtgtttttttattaaacaaattaaaa ctttcagtgacggatctcttggctctcgcatcgatg aagaacgcagtaaatcgcgatacgtaatgtgaattg cagaaatatgtgaatcatcgaatctttgaacgcatct tgcgctctggggtactcctcagagcatgcctgtttg agtgtcttttaattctcatctcataattttttattaa tttaaaataattataggtggatcgtggctgttttga cgacttaacctcgtctcagctgaaatatagaaagcg acgtctaaaattcagagtaataagatgttaacgtcg gcgtgataagtaaattacgcagtcagttttctgtct atctctctggtgttcgctacgaattactatagtttt gttttcaacatttgacctcaaatcaggtaggactac ccgctgaacttaagcatatcaataagccgg. tiraitirachium oryzae is a fungus that comes from the air, its interaction with humans was rst known to cause onychomycosis (naseri et al., 2013). this fungus has thebiosynthetic ability of agnps because it contains a single carbon and nitrogen in culture media which can be synergized into nanoparticles to inhibit bacterial growth (khlaifat et al., 2019). onychomycosis is also reported as a producer of extracellular lipase enzymes that can hydrolyze waste oil (al-limoun, 2020). this fungus belongs to the basidiomycota group and is often mistaken for ascomycota, this species produces spores in the air and is often found as endophytes in certain plant species, its presence in mesophyll tissue (agut, 2001). 3.5 purication and identication bioactive compound a total of 2 g of ethyl acetate extract of the endophytic fungus tritirachium oryzae (yf12) was obtained using a gradient (10:0-0:10) in ethyl acetate-methanol (9:1-5:5) to obtain ve fractions, namely f1-f5 made. fraction f4 was rechromatographed with an n-hexane-ethyl acetate gradient eluent (5:5-0:10) to produce a three-column fraction, f4.1-f4.3. column fraction f4.2 is a chromatographic column with nhexane-ethyl acetate (4:6) as eluent and the resulting solid is eluted with 8:2 n-hexane-ethyl acetate to obtain a pure yellowish color compound (compound 1) white solid 36 mg. the h-nmr spectrum of compound 1 (figure 3) showed the presence of nine proton signals. there are two doublet signals with the integration of two protons in the aromatic region, namely at 𝛿h 7.56 and 8.20 ppm. this indicates that © 2022 the authors. page 223 of 227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 figure 2. molecular examination results on selected fungal yf12 isolated from s. malaccense fruit (a) the composition of the number of nitrogen bases possessed by the yf12 fungi isolate was no. 1,753 bp, (b) the phylogenetic tree showing the species of yf12 isolate showed tritirachium oryzae species, the scale used was 0.050 m figure 3. the 1h-nmr spectrum of compound 1 (1h-500 mhz in cdcl3) compound 1 has two pairs of equivalence protons side by side. thus it is known that compound 1 is an aromatic compound that has a para-substituted benzene ring. then there are three oxymethine proton signals, namely at 𝛿h 4.16 (1h, m), 5.32 (1h, d, j= 2), and 5.78 ppm (1h, s), an oxymethylene proton signal at 𝛿h 3.99 ppm (2h, m), and a methoxy proton signal at 𝛿h 2.61 (3h, s). in addition, there are also two broad signals that are typical for hydroxyl protons, namely at h 3.55 and 7.19 ppm. the identication of protons in the 1h-nmr spectrum is supported by data on the 13c-nmr spectrum (table 4) and hmqc (figure 3). the 13c-nmr spectrum of compound 1 showed the presence of nine signals. 4 carbon signals appear in the aromatic region, namely two equivalent aromatic methine carbons (𝛿h 123.8 and 126.8 ppm), one aromatic quaternary carbon at 𝛿c 147.6, and one aromatic oxyaryl carbon at low eld 𝛿c 164.5 ppm. in addition, ve oxygenated carbon signals appear in the 𝛿c region of 40.0–75.0 ppm. the analysis of the proton and carbon nmrspectrawere conrmed by the data on the hmqc spectrum shown in figure 4a and table 4, namely the 1h-13c correlation through one bond. the hmqc spectrum showed seven correlations consisting of two correlations on the aromatic ring and ve correlations on oxygenated 1h-13c on aromatic substituents. the other two proton signals at 𝛿h 3.55 and 7.19 ppm do not correlate with the hsqc spectrum. this indicates that the two protons are hydroxyl protons. figure 4. the nmr 2d spectrum of compound 1 (1h-500 mhz; 13c-125 mhz in cdcl3 (a) hmqc spectrum, (b) hmbc spectrum, (c) the hmbc correlation and 𝛿-assignment of compound 1 the hmbc spectrum (figure 4) shows the 1h-13c correlation through two or three bonds. the aromatic proton signal at 𝛿h 8.20 ppm is correlated through three bonds with its equivalent aromatic carbon (𝛿c 123.8 ppm). the aromatic proton at 𝛿h 7.56 ppm is correlated through three bonds with equivalent aromatic carbon (𝛿c 126.8 ppm) and oxygenated carbon (𝛿c 73.5 ppm). furthermore, the oxygenated methine proton at 𝛿h 5.32 ppm was correlated via three bonds with the equivalent aromatic carbon (𝛿c 126.6 ppm) indicating that the oxygenated methine group is directly attached to the aromatic ring and is para-substituted with the hydroxyl group. the hmbc spectrum in figure 4b does not provide all the information for the 1h-13c correlation through two or three bonds. however, the substituent para hydroxyl group is a furan ring-substituted for hydroxyl and methoxyl groups which are indicated by the presence of a hydroxyl proton signal at 𝛿h 3.55 (1h, broad) and a methoxyl proton at 𝛿h 2.61 (3h, s). © 2022 the authors. page 224 of 227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 the 1d and 2d nmr spectral data for compound 1 are shown in table 4. table 4. nmr data for compound 1 no. c 𝛿c ppm 𝛿h ppm (σh. multiplicity. j (hz)) hmbc 2 73.5 5.32 (1h, d, j = 2) 126.8 3 66.2 5.78 (1h, s) 4 55.6 4.16 (1h, m) 5 64.1 3.99 (2h, m) 6 41.0 2.61 (3h, s) 1’ 147.6 2’ 126.8 7.56 (1h, d, j = 8.5) 126.8; 73.5 3’ 123.8 8.20 (1h, d, j = 8.5) 123.8 4’ 164.5 5’ 123.8 8.20 (1h, d, j = 8.5) 123.8 6’ 126.8 7.56 (1h, d, j = 8.5) 126.8; 73.5 3oh 3.55 (1h, broad) 4’oh 7.19 (1h, broad) basedonspectralanalysisof 1h-nmr, 13c-nmr,hmqc, and hmbc, it can be explained that compound 1 has a parasubstituted benzene ring between the hydroxyl group and the furan ring. the oxygenated methine carbon of this furan ring bonds directly to the aromatic carbon. the hydroxyl and methoxyl substituents are bonded to the furan ring. thus, the proposed chemical structure of compound 1 is 2-(4-hydroxyphenyl)-4-methoxytetrahydrofuran-3-ol as shown in figure 5. figure 5. chemical structure of compound 1: 2-(4-hydroxyphenyl)-4-methoxytetrahydrofuran-3-ol the results of the antioxidant test using the dpph method, the ic50 value was 53.03±0.23 with moderate criteria. chemical structure 2-(4-hydroxyphenyl)-4-methoxytetrahydrofuran3-ol, contains simple phenolic compounds, phenolic compoundsareknownasantioxidantsandantibacterials (zeb,2020). the group of antioxidant compounds present in the host, especially in s. malaccense fruit contains more complex compounds such as anthocyanins such as cyanidin 3-glucoside, followed by cyaniding 3,5-glucoside and peonidin 3-glucoside (batista et al., 2017; nunes et al., 2016), because anthocyanins are phenol derivatives other than avonoids (zeb, 2020). in the essential oil of guava fruit s. malaccense 2-phenyl ethanol and its esters (2-phenylethyl acetate, 2-phenylethyl isopentanoate, 2-phenylethyl benzoate and 2-phenylethyl phenylacetate) and herbs (1-octen-3-ol) contributes to the complexity of the aroma(pino et al., 2004). similarcompounds, such as 2(4-hydroxyphenyl)-5-(3-hydroxypropenyl)-7-methoxybenzofuran, which is a derivative of ailanthoidol, have been reported to have been isolated from a neolignan from zanthoxylum ailanthoides and salvia miltiorrhiza bunge. this compound has a low ic50 value, by activating protein kinases with the help of mitogens which can make this compound an eective functional chemical candidate for the prevention of inammatory diseases (kim et al., 2013). chemical constituents that have been reported are tetrahydroxanthone and oxyanthrone from tritirachium sp associated with pseudoceratina purpurea isolated from marine sponge collected from oshore sites in sakuraguchi, ishigaki island, okinawa prefecture, japan (ueda et al., 2010). there are three anthraquinone compounds from tritirachium sp by water-soluble tetrazolium-8 (wst-8) colorimetric assay, were shown to be antiproliferative against hela cells (ic50: 11, 17, and 17 m respectively) (ueda et al., 2010). there are 4,5-dihydroxy-10oxo-9,10-dihydroanthracen-9-yl acetate, and 2-(2-methoxy4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2htetrazolium compounds (zhang et al., 2017). the pinus wallichiana plant from the western himalayas, has been isolated from the endophytic fungus tritirichium oryzae and has high antifungal activity on candida albicans and a broad spectrum as an antimicrobial (qadri et al., 2014). in addition, this species is known to cause several infections in humans such as corneal ulcers, otomycosis, onychomycosis, and dermatomycosis, but the genus tritirachium also has potential in biotechnology to produce several enzymes such as proteases, amylase, glucanase, xylanase, pectinases, lipase, and proteinase k, phylogenetically, it is known that the fungus tritirachium oryzae is closely related to t. dependents (bezerra et al., 2020). another host plant known to host tritirachium oryzae is the bark of the hancornia speciosa gomes plant, which has biological activity as an antibacterial against b. subtilis, e. coli, and p. aeruginosa bacteria (chagas et al., 2017). isolation of fungi of the tritirachium genus from the soil of various gardens in shiraz, iran was found as much as 0.24%, at a ph between 7-8, which are referred to as keratinophilic fungi (pakshir et al., 2013). there is a diversity of species of tritirachium oryzae isolated from transgenic and non-transgenic “bt” cotton plants (the commonly farmed cotton plant that has been genetically engineered) on leaves and stems in brazil (vieira et al., 2011). © 2022 the authors. page 225 of 227 hapida et. al. science and technology indonesia, 7 (2022) 220-227 mangrove plants on the southwest coast of india, the genus tritirachium has antimicrobial activity as well (maria et al., 2005). 4. conclusions code yf12 was tritirachium oryzae from s. malaccense produced secondarymetabolites compound. compound 1 as 2-(4hydroxyphenyl)-4-methoxytetrahydrofuran-3-ol with moderate of antioxidant activity. for increasing the antioxidant activity of compound 1, further research is needed, namely a semisynthetic reaction to add a hydroxyl group at the c-3 and/or c-5 positions. so this compound 1 can be used as a basic ingredient of antioxidant compounds. 5. acknowledgment the authors thank to the drpm 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(2020). concept, mechanism, and applications of phenolic antioxidants in foods. journal of food biochemistry, 44(9); e13394 zhang, h., z. zhao, and h. wang (2017). cytotoxic natural products from marine sponge-derived microorganisms. marine drugs, 15(3); 68 © 2022 the authors. page 227 of 227 introduction experimental section materials plant material isolation of endophytic fungi cultivation and extraction antioxidant activity test morphological and molecular identification of endophytic fungi measurement of product acidity results and discussion endophytic fungi of the fruit of s. malaccense morphological identification of endophytic fungi antioxidant activity of endophytic fungi molecular identification of selected endophytic fungi purification and identification bioactive compound conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 3, july 2022 research paper study of the electrical, optical and morphological properties in submicron and microstructured zno thin films obtained by spin coating and chemical bath deposition c. lópez-esmerio1, c. ruiz-rojas2, j. angulo-rocha3, e. lizárraga-medina4, f. ramos-brito5*, e. camarillo-garcía6, r. martinez-martinez7, m. aguilar-frutis8, m. garcía-hipólito9 1master student at posgrado en ciencias físicas, instituto de física, universidad nacional autónoma de méxico, ciudad de méxico, 01000, méxico2phd student at posgrado en tecnología avanzada at cicata-legaria, instituto politécnico nacional, ciudad de méxico, 11500, méxico3hospital de la mujer, secretaría de salud sinaloa, culiacán, 80020, méxico4master student at posgrado en tecnología avanzada at cicata-legaria, instituto politécnico nacional, ciudad de méxico, 11500, méxico5laboratorio de síntesis de materiales, facultad de ciencias físico matemáticas, universidad autónoma de sinaloa, ciudad universitaria, culiacán, 80000, méxico6instituto de física, universidad nacional autónoma de méxico, ciudad de méxico, 01000, méxico7universidad tecnológica de la mixteca, oaxaca, 69000, méxico8cicata-legaria, instituto politécnico nacional, ciudad de méxico, 11500, méxico9instituto de investigaciones en materiales, universidad nacional autónoma de méxico, ciudad de méxico, 04150, méxico *corresponding author: framosbrito@uas.edu.mx, ramosbritof@gmail.com abstractin the present work the synthesis of zno semiconductor thin films was performed successively using spin coating and chemicalbath deposition techniques. the deposition was made by varying the concentration of zinc acetate and hexamethylenetetramine(hmta: znac) in the precursor solution. this process led to two preferred growth directions (002) and (101), both with very similartexture coefficients, too; a noticeable change in morphology of structured surface, variation in unit cell parameters and crystallinegrain size. all the films turned out homogeneously submicro and microstructured and with a wurtzite-type hexagonal crystallinestructure. using pre-loaded mathematica 11.3 software functions and an algorithm developed in it, the micrographies were analyzedto calculate the percentage of substrate-covered area which was always greater than 80%. likewise, it also found that resistivitydecreases at a higher percentage of covered area and that the variation in the shape of the photo luminescent emission spectrumcan be considered as a qualitative indication of the concentration of charge carriers. keywordszno semiconductor, nanostructured films, texturized films, n-type semiconductor received: 19 february 2022, accepted: 31 may 2022 https://doi.org/10.26554/sti.2022.7.3.291-302 1. introduction over the past decade, semiconductor research has grown considerably. this is due to the potential applications they may have, as well as the fact that nowadays we have better infrastructure at hand, such as better labs and supercomputers. the eld of application of semiconductor materials is very wide and varied, they are present in products as common as sunscreen but also in the most sophisticated electronic devices, without exception of those that are now considered essential by most human beings to carry out their daily lives, such as: smartphones, televisions, tablets, and computers, which are now the trend for the semiconductor industry (yeap, 2013). likewise, they also made a dierence in the lucratively growing area of lighting devices, this, since the introduction of led in the 60’s and its constant improvement since then (gayral, 2017; weisbuch, 2018). there are other areas where the introduction of semiconductor materials has played an important role for their development, such as: food, health, energy, and environment (weisbuch, 2018; nanda et al., 2017; karthikeyan et al., 2020; zhu and zhou, 2019); a clear example for this is the use of semiconductors in the production of solar cells that can convert solar energy into electricity, or the treatment of sewage waters through photocatalysis using semiconductor materials. the formerly-mentioned great success of semiconductors is due to the large amount of knowledge generated on them as a result of the investigations carried out on their dierent properties: morphological, optical, electrical, chemical, etc., only in this nearly-concluding decade, it has been reported, according to the central library’s online database from universidad nacional autónoma de méxico (bc.unam.mx), 977 591 https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.3.291-302&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.3.291-302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 scientic publications that mention the word semiconductor and are estimated to be around 2,076,660 for the next decade. the notable development reported by the dierent areas when theyincorporate semiconductors in its processes has led to hard work in the semiconductor research from dierent areas: both experimental, numerical calculations with supercomputers and theory, all in the same direction, getting better semiconductors with certain properties that help to solve dierent needs. zinc oxide is one of the semiconductors that have recently caught the attention of multiple research groups, in the rst decadeof thiscentury,accordingtothedatabaseof thebc.unam. mx, 413 scientic publications were reported for “zinc oxide semiconductor” and in this near-to-end decade, it has been reported in the order of 1420, estimating the order of 5500 publications for the next decade. zno is considered an attractive and potentially promising semiconductor for a wide variety of applications, this is because it has an energy gap of 3.37 ev, exciton link energy 60 mev to 300◦k (özgür et al., 2005a), in addition to being transparent in the visible region of the wavelength spectrum. among the possible applications for zno there are: ultraviolet (uv) lasers (zktang et al., 1998), light emitting diodes (led) (park et al., 2010), pn junction devices (bian et al., 2004), transparent thin lm transistors (carcia et al., 2006), gas sensors (chou et al., 2006), and dental cements considering that its biosecurity has been proven (nguyen et al., 2019). furthermore, 10 years ago it was revealed that zno nanoparticles have the potential to selectively kill tumor cells, performing studies with dierent tumor entities (hanley et al., 2008; vandebriel and de jong, 2012; pandurangan et al., 2016; wahab et al., 2016; chandrasekaran and pandurangan, 2016; gupta et al., 2015; kc et al., 2016; hassan et al., 2017), although the exact mechanism of cytotoxicity is still subject to debate (vandebriel and de jong, 2012). various synthesis techniques have been used to grow zno lms (lu et al., 2007; kim et al., 2000; lu et al., 2000; zhang et al., 2010; shinde et al., 2010; muiva et al., 2011) but it is important to highlight those that oer simplicity, high growth rate, homogeneity and production at a low cost. among these, some of the most common are spin coating and chemical bath deposition. there are works that report the growth of microandnanoznobarsonbuersdepositedbyspincoating using chemical bath deposition (chen and ting, 2016; wu et al., 2010; rana et al., 2017; suhaimi and yuwono, 2019; chang et al., 2017), that is, using a process that involves these two techniques. the virtue of employing this process is that it allows growing micro/nano zno bars aligned and oriented (chang et al., 2017). the buer layer deposition provides nucleation centers that reduce interface energy between the substrate and the reagents and allows the vertically aligned bars to form at the substrate surface due to heterogeneous nucleation. the morphology, the degree of alignment, the density, crystalline quality and optical properties of micro and nano bars are directly related to the parameters of the buer (chang et al., 2017). likewise, the study on the eect that this buer has on the properties of the micro and nano bars has concluded that the diameter of these increases linearly with the crystalline grain size of the buer (chang et al., 2017), that the length of these is proportional to the time in the chemical bath as t1.5 and that the area density decreases with the roughness of the buer layer (chen and ting, 2016). there are very signicant advances in potential applications for zno, specically in those that imply that it has an optimal semiconductor property, two examples of this are: 1) as a transparent conductive oxide, there are works where the properties of commercial ito, and zno thin lms doped with indium (i) gallium (ga) and aluminum (al) are compared, having very similar resistivities, of the order of 10−4 ω.cm, with zno presenting higher mobility (gonçalves et al., 2011) and 2) in led’s (rahman, 2019), zno is presented as the naturally most viable semiconductor to replace gan in diode manufacturing for short wavelength light emitters due to the zno energy gap and its exciton link energy that it is more than twice that of gan; however, much remains to be done. the research reported in this direction shows that a way to deal with the vicissitudes that have been presented, is through systematic studies on the synthesis of zno as a function of the dierent synthesis parameters, this through synthesis processes that allow: reproduce the zno obtained, such as spin coating and chemical bath deposition, as well as induce changes in its electrical properties based on its other properties such as: morphology, crystal structure, texture and optical properties, among others. this in order to study the former as a function of the latter and fully understand the dierent processes that give it its semiconductor property and the correlation between them. surely this will allow, in the future, to develop a synthesis process that is attractive and scalable at the industrial level to manufacture zno in line with specic semiconductor characteristics that allow its incorporation in the market and the partial or total displacement of the material to replace. this work presents an investigation that deals with the synthesis and systematic characterization of zno micro / nano structured semiconductor lms by deposition by chemical bath deposition on glass substrates previously coated with a layer zno buer by spin coating. for this work, a systematic synthesis of microstructured zno was achieved through a process employing spin coating for the deposition of a buer layer over glass substrates, followed by chemical bath deposition to grow a microstructured thin lm of zno over the buer. the objective for this investigation work is to obtain lms with varying morphology and texture, in addition to seeing how those variations can aect optical and electrical properties for zno. among the results obtained there is the fact that: the synthesis process used favors two preferred texture directions, (002) and (101) depending on the synthesis conditions and without noticeable changes between the coecients of texture both for address (002) and address (101); the concentration of charge carriers was found to be higher for the textured lms in the address (101) than for those in address (002); the higher the percentage of substrate-covered area, the lower the resistiv© 2022 the authors. page 292 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 ity, regardless of the morphology and texture; the dierence between photoluminescent emissions associated with donor defects (zni0 y zni) and vzn acceptors can be considered as a parameter indicative of the charge carrier concentration; the greater the dierence, the greatest the concentration of n-type charge carriers. these results encourage the use of high resolutionphotoluminescencespectroscopytoquantitativelymeasure the dierence between type “n” and “p” charge carriers in zno. this could place photoluminescence spectroscopy as an optical method for characterizations that until this day are done only via electrical techniques. 2. experimental details 2.1 synthesis thin lms of zno were synthesized on glass substrates, the techniques used in the synthesis were spin coatingand chemical bath deposition, by means of the rst one the lm that served as a buer layer to later grow the second one on it. for buer lms the precursor solution was prepared with zinc acetate dehydrate ((ch3coo)2zn.2h2o) from the brand j.t. baker usa and methanol with a purity of 99.8% as solvent, with a concentration of 0.06 m (200 ml of methanol and 2.63 g of zinc acetate). the spin coating process was done with a kw-4a spin-coater model from chemat technology, the equipment was congured with two turning stages, the rst at 800 rpm for 9 s and the second at 2500 rpm for 30 s. for each buer lm, was used a droplet of 100 `l, then, after spinning the glass was placed on an ika brand grill hs-7 model for 10 minutes at 80◦c. the synthesis of zno thin lms was achieved by chemical bath deposition, using the same zinc precursor as above mentioned and adding deionized water with a resistivity of 18 mω as solvent, in addition, an organic compound that acts as a complexingagentwasadded, hexamethylenetetramine ((ch2)6n4). for the precursor solution, the zinc acetate solution was dissolved in deionized water at 0.024 m, this solution was divided into 7 beakers to which hexamethylenetetramine (hmta) was added. to achieve homogeneity in the solution this was placed for5 minutes in an ultrasonic bath in a from the brand branson, model 1800. the samples were then placed in the chemical bath at a temperature of 78◦c for 12 hours. the parameter that was varied was the relative concentration between zinc acetate and hmta (hmta: znac) in the precursor solution, the ratios were: 0.0625: 1, 0.125: 1, 0.1875: 1, 0.3125: 1, 0.375: 1, 0.54: 1, and 0.625: 1, which from here on will be named c1, c2, c3, c4, c5, c6, and c7, respectively. 2.2 characterization the diraction patterns of all zno lms, figure 1, were obtained with a diractometer from the brand bruke model d8 advance. the crystallite size (d) strain (y), stress (𝜎) and energy density (u) values were calculated by using scherrer formula and the modied williamson-hall method (w-h) (kalita and kalita, 2015), the results are shown in table 1. the texture coecient was obtained at from the intensities of (100), (002), and (101) peaks and considering the following equation (wang et al., 2015): figure 1. a) results of x-ray diraction (xrd) analysis for all samples showing their miller indexes corresponding to wurtzite type crystalline structure; b) enlarged xrd pattern for the zone of the (100), (002), and (101) planes, the inserts are an enlargement of the diraction peaks corresponding to the planes (002) and (101) that show the variation of the unit-cell dimensions tchkl = ihkl i0hkl { 1 n ∑︁ n ihkl i0hkl }−1 (1) where tc(hkl) is the texture coecient of the planes hkl, i(hkl) is the measured intensity of the peak, i0(hkl) is the intensity of the planes hkl in a sample that shows no growth or preferential orientation and n is the number of diractions considered in the analysis. the micrographs of the samples were obtained using the atomic force and scanning electron microscopies (afm and sem), using the thermo microscopes veecomodelautoprobecpandjeolmicroscopemodel jsm6390lv, respectively. the electrical properties of the zno lms were obtained with a kit from the brand ecopia, model hms-3000 that measures hall voltage. photoluminescence spectra of the samples was obtained with an edinburg fls980 spectrometer. theexcitationwavelengthofchoicewas325nm, corresponding to a local maximum for the excitation spectrum of sample c7, which resulted to appear in all samples. the © 2022 the authors. page 293 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 table 1. d, y, 𝜎 and u values for all samples extracted from plots in figure 2 that correspond to scherrer and w-h analysis of xrd patterns of the samples sample scherrer method w-h method (100), (002), (101) peaks all peaks udm usdm udedm d d y d y 𝜎 d y 𝜎 u (nm) (nm) 10−3 (nm) 10−3 (mpa) (nm) 10−3 (mpa) (kjm−3) c1 29.73 112.72 59.74 1.15 59.11 1.06 133.25 60.85 1.11 139.43 77.51 c2 34.25 126.05 63.87 1.10 61.10 0.96 120.50 63.79 1.03 129.44 66.80 c3 27.73 254.31 66.96 1.63 62.15 1.45 182.54 65.82 1.55 193.84 149.80 c4 33.85 93.68 54.35 0.76 54.24 0.67 84.39 55.48 0.72 89.83 32.17 c5 32.20 114.59 56.80 1.02 54.03 0.86 107.39 56.57 0.93 117.40 54.95 c6 28.09 171.70 53.31 1.35 53.24 1.26 157.50 54.65 1.31 163.83 107.28 c7 34.31 117.50 60.00 0.91 57.47 0.77 96.69 59.84 0.84 105.20 44.13 transmittance of the samples was obtained using the uv-visnir cary 5000 spectrophotometer. the percentage of the covered areaof the substrate was calculated using the procedure shownin theelectronic supplementarymaterial, which includes preloaded functions of mathemática 11.3 and an algorithm developed in it. the dimensions of the individual elements that made up the microstructure of the lms were obtained by analyzing the sem images using the "imagej" software (rasband, 2012). 3. results and discussion 3.1 crystalline structure figure 1a shows the diractograms of all samples, all of them present the peaks corresponding to the planes (100), (002), (101), (102), (110), (103), and (112) corresponding to the wurtzite type crystalline structure of zno. the gure shows that, except samples c4 and c6 that presented a preferential growth of the planes (101) and texturization of the surface in <101> direction, all the others presented a preferential growth of the planes (002) and texturization of the surface in direction <001>. the texture coecients in the direction <001> for samples c1, c2, c3, c5, and c7 were: 2.7947, 2.8696, 2.9338, 2.7768, and 2.7794, respectively; while texture coecients in direction <101> for samples c4 and c6 were 1.7857 and 1.9303, respectively. figure 1b presents the diractograms for all samples, for a 2\ interval of (28.0, 37.8)◦, which corresponds to the region of diraction peaks associated with crystalline planes (100), (002) and (101) of zno. with the intention of pointing out the existing dierences between all diraction peaks of a same crystallographic plane for each sampes, an enlargement of respective zones was made for the diractogram; these enlargements can be found in the inserts of figure 1b. insert 1 shows a small shift of the (002) peak towards the right in comparison to the position of that same peak for sample c2, this indicates a dierence between interplanar distances for the samples with a prefered growth in the <001> direction, being c2 and c3 the highest and lowest values, respectively. insert 2 shows that the peaks corresponding to planes (101) are all centered arround the same value, which would mean that the interplanar spacing did not varyforsamples with apreferential growth in the <101> direction. taking the bragg angle values of diraction peaks, the interplanar distances “d” of that planes were calculated through the equation known as the bragg’s law (cullity and stock, 2001): n_ = 2dsin \ (2) where n is the order of diraction, _ the wavelength of the x-rays and \ the diraction peak in question. once the interplanardistances were calculated, the unit-cell parameters were calculated, this by means of the equation that relates “d”, the miller indices of the planes (hkl) and the “a” and “c” unit-cell parameters for a hexagonal structure (cullity and stock, 2001): 1 d2 = 4 3 (h2 + hk + k2) a2 + l2 c2 (3) the volume v of the unit-cell was obtained knowing that v= 0.866a2c (wang et al., 2015). table 2 shows the results obtained from v, a, c for all samples. the cell volume reached vary from 47.4344 to 47.6035 å3 and the unit cell parameter "c" from 5.1886 to 5.1999 å. the corresponding w-h plots (figure 2) showed that broadening of the diraction peaks was essentially isotropic. this indicates that diracting domains were isotropic and there was also a microstrain contribution. table 1 shows d, y, 𝜎, and u values for all samples. there are two columns for d value by scherrer equation, for the rst column was considering only (100), (002) and (101) diraction peaks and for the second one all diraction peaks were considered. there is a remarkable dierence between values of d obtained in these two dierent ways, which drives to consider the lattice strain factor for © 2022 the authors. page 294 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 figure 2. . estimation of crystallite size (d), lattice strain (σ), stress (𝜎) and energy density (u) by scherrer and w-h methods. (a) scherrer method to calculate d of all samples considering all peaks in their corresponding diractions patterns. plot of cos \ vs 1/𝛽. (b) uniform deformation model of w-h method. (c) uniform stress deformation model of w-h method. (d) uniform deformation energy density model of w-h figure 3. atomic force microscopy results for all samples. each sample was analyzed at two dierent resolutions in order to show microstructure details. a, b) sample c1; c, d) sample c2; e, f) sample c3; g, h) sample c4; i, j) sample c5; k, l) sample c6; and m, n) sample c7 table 2. results obtained from a, c and v for all the samples sample a c v (å3) (å) (å) = 0.866 a2c 0.0625:1 (c1) 3.2528 5.1905 47.5600 0.1250:1 (c2) 3.2513 5.1999 47.6022 0.1875:1 (c3) 3.2510 5.1886 47.4900 0.3125:1 (c4) 3.2497 5.1999 47.5554 0.3750:1 (c5) 3.2500 5.1943 47.5129 0.5400:1 (c6) 3.2468 5.1958 47.4331 0.6250:1 (c7) 3.2507 5.1999 47.5846 d calculation. table 1 shows the values of d obtained from udm, usdm, and udedm, which are approximately similar, indicating that the inclusion of strain in various forms of w-h method has a very small eect on the average crystallite size of sub-microstructured zno lms. the crystallite size resulted from w-h method was in a size of around 58.73 nm, which is in agreement with microstructure results obtained by afm for all samples, for example: afm images in figures 3b and 3f show the microstructure of samples c1 and c3, respectively. however, the dierence between d values obtained from the scherrer formula and w-h methods is large, showing that is essential to estimate d by considering both crystallite size and lattice strain contributions in the widening of the diraction peaks. this large dierence was associated with the great contribution of heterogeneous microstrains in the widening of the diraction peaks (zhang et al., 2020). these microstrains are due to dislocations in grain boundaries regions (zhang et al., 2020). zhang et al. (2020) conclude in their work that assuming grain boundary structures in nanocrystalline and coarse grain materials are very similar, then the dislocation density in the grain boundary (gb) regions is almost like a material constant depending mostly on the misorientation and structure of gbs. they proposed a model that shows, on one hand, that when the grain size is smaller than about 20 nm and the grain interior regions become more-or-less free from dislocations the average dislocation density in the crystal can still be substantially large. at these small grain size values, the volume fraction of gbs becomes signicant and the dislocation density in gbs becomes dominant in the entire crystal. on the other hand, even in coarse grain polycrystals, the gb regions do consist of substantial dislocation densities. other authors whose research is about nanoparticles (bindu and thomas, 2014; solati and dorranian, 2017) and nanolms (yamada et al., 2007), they have reported only small dierences between results obtained from scherrer formula and w-h method attributing this to the dierence in averaging the particle size distribution (bindu and thomas, 2014; solati and dorranian, 2017; yamada et al., 2007). figure 4 presents the "c" parameter and volume of the unitcell plotted as a function of the relative concentration of hmta in the precursor solution. it is appreciated that apparently there © 2022 the authors. page 295 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 is no correlation between these physical characteristics of the sample and the hmta concentration. figure 4. parameters and volume of the unit-cell plotted as a function of the relative concentration of hmta in the precursor solution 3.2 microstructure figures 3 and 5 show the afm and sem micrographs of all the samples, respectively. the congruence between the images obtained for each of the samples by both techniques, afm, and sem, denote the good quality of the deposit in terms of homogeneity along the entire surface of the substrate. all samples resulted in microstructured lms. the c1, c2, c3, c4, and c5 lms were made up entirely of zno bars that were moderately oriented perpendicular to the substrate and with apparently hexagonal cross section, while lms c6 and c7 were made up of corn ake-like structures oriented almost perpendicular to the substrate plane. at rst glance it can be seen that the samples c1, c2 y c4 show empty spaces between the bars, that is to say, spaces where the deposition of zno has relatively poor, the table 3 presents the results obtained for the percentage of substratecovered area, in addition to: the diameter average of the cross section of the bars for samples c1, c2, and c5, the edge of the hexagonal cross section for sample c4, the thickness of the sheets in the samples c6 and c7 and the texture coecient. the results for the diameter show a dierence of up to an order of magnitude between the thinnest bars of the c2 sample and the thickest of the c3 sample. all zno bars show a nodular type growth and nanostructured hexagonal cross section with an average roughness of the order of crystallite grain size, i.e. for sample c1 the average roughness obtained by afm was 24.9 nm that is consistent with its grain crystalline size of 26,975 nm calculated by scherrer formula for the planes (002), as was shown in table 1, which seems to indicate that the figure 5. scanning electron microscopy results for all samples. each sample was analyzed at two dierent resolutions in order two show microstructure details. a, b) sample c2; c, d) sample c3; e, f) sample c4; g, h) sample c5; i, j) sample c6; and k, l) sample c7 nanostructures of the hexagonal upper face are single crystals of zno. table 3 shows the values of roughness considering an area of 10×10 `m2. these values turned out to be: 63.1, 33.0, 50.0, 46.4, 47.8, 66.2, and 35.4 nm, for samples c1, c2, c3, ..., c7, respectively. all the samples presented gauss-type histograms for the distribution of the measured heights, practically symmetrical, with no apparent bias, except for sample c1, which showed little bias pronounced towards heights of lesser value. this rearms what has been said about the degree of homogeneity of the coatings. 3.3 electrical properties figure6showstheresultsobtainedforresistivity(ω·cm), charge carrier concentration (1/cm3) and mobility (cm2/v·s) of all samples. it is observed that samples that resulted with higher resistivity and practically in the same order of 60 ω·cm were c1 and c2, while the rest presented lower resistivities in up to one order of magnitude, as is the case of c3, which turned out to be the one with the lowest resistivity with 4.02 ω·cm. likewise, samples c1 and c2 also had the fewest charge carrier concentration with values of 1.68 and 1.19×1017 1/cm3, respectively, while samples c4 and c6 textured in address <101> resulted in the highest number of charge carriers with values of 6.84 and 6.31×1018 1/cm3, but with the lowest mobility with values of 0.34 and 0.29 cm2/v·s, respectively. sample c1, which, as already mentioned, turned out to be the sample with greater mobility of 3.08 cm2/v·s, up to an order of magnitude greater than those of c4 and c6, however; with a very low number of charge carriers. figure 6 shows that the number of charge carriers for samples c1, c2, and c5 is smaller than that for sample c3, while for samples c4, c6, and c7 it is bigger. additionally, carrier mobility values for samples c1, c2, and c5 are much higher than for sample c3, but lower for samples c4, c6, and c7. this is not in agreement to the results presented formicrostruc© 2022 the authors. page 296 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 table 3. results obtained for the percentage of substrate-covered area, the diameter average of the bars, the thickness of the sheets of the samples, and the texture coecient from all samples sample substratecovered diameter average edge of the hexagonal thickness of the texture coecient area (%) (nm) cross section sheets <001> <101> 0.0625:1 (c1) 94.72 338 —– —– 2.7947 0.0789 0.1250:1 (c2) 81.52 126 —– —– 2.8696 0.0745 0.1875:1 (c3) 99.61 1268 —– —– 2.9338 0.0300 0.3125:1 (c4) 98.46 —– 402 —– 0.6374 1.7857 0.3750:1 (c5) 85.33 186 —– —– 2.7768 0.1353 0.5400:1 (c6) 99.85 —– —– 25 0.5820 1.9303 0.6250:1 (c7) 99.81 —– —– 30 2.7794 0.1000 figure 6. results obtained for resistivity (ω·cm), charge carrier concentration (1/cm3), and mobility (cm2/v·s) plotted as a function of the relative concentration of hmta in the precursor solution ture, as samples c1, c2, and c5 show spacings between rods, where material deposition is insucient, which was expected to aect the mobility of the carriers, and was not the case. on the other hand, the surface of the zno rods in these same samples, appears to be relatively smooth, which could represent fewer defects and consequently a lower quantity of charge carriers. contrastingly, samples c4, c6, and c7, are practically free of gaps and are composed by sub-micrometric structures with a nanostructured surface resulting in higher values for charge carriers. 3.4 optical properties figure 7 shows the photoluminescent emission spectra of all samples when excited them with a _ex= 325 nm, as well as excitation spectra for sample c7 when considering the emission _em= 395, 420 and 620 nm. photoluminescence emission spectra for all samples (figure 7b) presents the characteristic emission spectra for zno (angulo-rocha et al., 2017; félixquintero et al., 2017; ramos-brito et al., 2011). it shows a narrow emission band centered around near-uv wavelength, which is associated to an exciton-related electronic transition. in addition, it exhibits a broad emission band in the visible range of the electromagnetic spectrum, typically associated with defects in the crystalline structure of zno. additionally, besides the se two particular bands, an emission band can be found around 410-490 nm, which intensity will vary depending on the sample. figure 8 presents a deconvolution of the emissionspectra forsamplec3, it canbeobservedthat thespectrum itself can be seen as one composed of distinct emission bands centered around 387, 395, 411, 439, 602, and 688 nm. referring to the works previous (angulo-rocha et al., 2017; félix-quintero et al., 2017; ramos-brito et al., 2011), emission bands were associated with electronic transitions between dierent states of energy introduced into the zno energy band gap due to its following intrinsic defects: neutral interstitial zinc (zni0), zinc vacancies (vzn), interstitial zinc (zni), oxygen antisite (ozn), and interstitial oxygen (oi). this according to the energy diagram in figure 9. in this it is observed that the emission centered at 387 nm is associated with the electronic transition zni0 → vb, emission centered at 395 nm with the cb → vzn transition, emission centered at 411 nm at zni0 → vzn electronic transition, the emission of 439 nm to the electronic transition zni → bv. the band centered at 602 nm at the cb → ozn and cb → oi transitions and nally, the band focused on 688 nm was associated with the electronic transitions zni → ozn and zni → oi, which is consistent with what was reported özgür et al. (2005b) and recently by siva et al. (2019). these latter observed a yellow band (574-587) nm that they associate with the presence of oi and a band between (678-729) nm associated with excess oxygen or oxygen vacancies (v0) sites. surely at the time of deconvolution of the emission spectrum (figure 8) it was also possible have considered the occurrence of v0, as reported in previous work for deposited zno using spray pyrolysis (angulo-rocha et al., 2017) where the presence was considered of v0 due to the rel© 2022 the authors. page 297 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 atively intense emission in the region of (460-510) nm, but as already it had been observed in previous work (félix-quintero et al., 2017; ramos-brito et al., 2011) and now in this one, apparently when the synthesis is by chemical bath deposition the emission in this region is relatively poor, which is why it was not considered. low intensity luminescent in the region of (460-510) is associated with the poor presence of v0 because the synthesis is carried out in a oxygen-rich environment (özgür et al., 2005b). figure 7. a) excitation spectra for sample c7 when considering the 395, 420 and 620 nm emission wavelengths as well as b) photoluminescent emission spectra of all samples when excited them with a wavelength of 325 nm figure 8. deconvolution of the emission spectrum of sample c3. it shows bands of emission centered at 387, 395, 411, 439, 602 and 688 nm that were associated with the presence of defects in the crystalline structure of zno. the insert shows the transmittance spectrum for sample c3 which is representative of all samples due to the position of the donor and acceptor defects in the “band gap” (see figure 9) it can be concluded that the ones that mostly aect the conductivity of zno are: zni0, zni, and vzn, since the energy distances of ozn and oi from vb are large enough involving high activation energy; considering this fact and in order to investigate a possible correlation, at least qualitative, between the quantities of these defects and the concentration of charge carriers measured by hall eect, the table 4. relative percentage amounts of the donor defects zni0, zni, and acceptors vzn calculated from the intensities of their corresponding photoluminescent emission bands sample amount of donor defects "n" (%) amount of acceptor defects "p" (%) dierence "n"-"p" (%) c1 0.701092351 2.546962517 -1.845870166 c2 12.32504424 8.688540241 3.636504000 c3 17.58026106 11.78783564 5.792425420 c4 20.05841157 9.975875551 10.08253602 c5 1.340338616 5.404254271 -4.063915654 c6 14.90788871 10.93850050 3.969388210 c7 21.13800263 12.48812969 8.649872935 percentage intensities of the emission bands centered at 387, 395, and 439 nm were calculated, and as a rst approximation associated with the relative percentage amounts of the donor defects zni0, zni and acceptor vzn. table 4 presents these results, it can be seen that samples c4, c7, c3, and c6 are the highest value, in order from highest to lowest, for the difference between the number of defects zni0, zni donors and vzn acceptor, consistent with those with the highest number of c4, c6, c7, and c3 charge carriers, almost in the same order from highest to lowest, except for the c6 shows that in principle the dierence between defects should have been greater than c7 and c3 and less than c4. this seems to indicate that a correlation exists between the relative concentration of type “n” and “p” charge carriers and the dierence of intensities for emission peaks associated with the bands for zni0 → vb, cb → vzn and zni → bv. these results encourage the use of high resolution photoluminescence spectroscopy to deconvolute said emission bands to obtain enough precision to quantitatively measure the dierence in intensities and therefore the dierence between type “n” and “p” charge carriers in zno. this could place photoluminescence spectroscopy as an optical method for characterizations that until this day are done only via electrical techniques. the insert of figure 8 shows the transmittance spectrum for sample c3 which is representative of all samples. the transmittance for all samples was not greater than 70% in the visible region, being c1 the one with the lowest transmittance 40%. they all started with their value highest at 750 nm, in the case of c3 it starts at ∼ 70% for 750 nm, and they presented a drop pronounced due to intrinsic defects in its crystalline structure. theenergybandgapofall thesampleswereobtained using the tauc method (viezbicke et al., 2015), resulting in: 3.19, 2.8, 3.18, 3.25, 3.05, 3.26, and 3.19 ev for, c1, c2, ..., c7, respectively. 3.5 implications of morphology, texture, and crystallite size on electrical properties figure 10 shows the resistivity as a function of: percentage of substrate-covered area, average diameter of the bars or thick© 2022 the authors. page 298 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 figure 9. energy diagram that shows indistinctly the dierent de-excitation paths for bars or sheets of zno ness of the sheets, average crystalline grain size and texture direction, of samples. figure 10a shows that for all samples there is the tendency that the highest the percentage of substratecovered area, the smaller the resistivity except for c1. this exception can be attributed to the fact that it is c1 the one having the least percentage of donor defects (see table 4). figures 10a and 10b show for samples c1, c2, c3, and c5 that the greatest the diameter of the bars, the greater the percentage of substrate-covered area, therefore, the contribution that diameter of the bars has in the resistivity is implicitly contemplated when considering the contribution that substrate-covered area has in the resistivity. a correlation between resistivity and texture coecient was not found. samples c1, c2, c3, c5, and c7, textured in the <001> direction have too similar texture coecients, with a relative percentage dierence between them less than 5% (see table 4), while the resistivity between them diers from up to an order of magnitude (see figure 6). the mobility of the charge carriers in a thin lm is necessarily inuenced by the crystalline grain size, percentage of substrate-covered area, texturing direction, and microstructure of the sample in question. figure 6 and table 3 show that mobility for samples c1, c2, c3, c5, and c7, textured in the direction <001>, increases as the substrate-covered area increases even if the crystalline grain size decreases, being then figure 10. it shows the resistivity of all samples as a function of: a) percentage of substrate-covered area, b) average diameter of the bars or thickness of the sheets, c) average crystalline grain size and d) texture direction the substrate-covered area a preponderant factor in mobility. this happens even when a decrease in the crystalline grain size could implies an increase of the crystal dislocations that should means greater dispersion centers for charge carriers and therefore less mobility of them. the results shown in figure 6, table 1 and table 1 show that when you have a covered percentage of the area larger than 95% the major factor in mobility appears to be the crystalline grainsize, just as if theamountofcrystaldislocationsdominates mobility. thiswasobservedwhenmobilitycomesfrom3.0803 cm2/v·s for sample c1 that has a substrate-covered area of 94.72% and particle size of 29,731 nm to mobility of 0.8334 cm2/v·s for the c3 sample that has a substrate-covered area of 99.61% and grain size of 27.731 nm. the change in the microstructure of the thin lm could be a relevant factor in mobility. this was observed when mobilityof sample c7 that has substrate-covered areaof 99.81% was less in an up to a 65.2% than mobilityof c2 that has substrate-covered area of 81.52%. indealingwith thesamplesc4andc6textured in thedirection <101> their values for the crystalline grain size, percentage of substrate-covered area, texturing direction and microstructure are too similar, which is consistent with the similarity between its values for resistivity, charge carrier concentration and mobility. the small dierence between their values for the charge carrier concentration is consistent with the dierence between their values for the relative percentage amounts of donor and acceptor defects (see table 4). © 2022 the authors. page 299 of 302 lópez-esmerio et. al. science and technology indonesia, 7 (2022) 291-302 4. conclusions the deposit by spin coating followed by chemical bath allowed the synthesis of zno lms. the seven samples resulted in microstructured lms. the c1, c2, c3, c4, and c5 lms were made up entirely of zno bars that were moderately oriented perpendicular to the substrate and with apparently hexagonal cross section, while lms c6 and c7 were made up of corn ake-like structures oriented almost perpendicular to the substrate plane. all zno bars show a nodular type growth and nanostructured hexagonal cross section with an average roughness of the order of crystallite grain size. the experiment allowed the synthesis of zno lms with hexagonal crystalline structure (a= 3,250 å and c= 5,195 å), average crystalline grain size of 31.95 nm and a shaped surface, for the most of the samples, by hexagonal bars with diameters that varies between 126 and 1268 nm. the increase in the diameter of the bars induces a higher substrate-covered area. the synthesis process favors two texture directions, (002) and (101) without noticeable changes between the texture coefcients for both. the <101> textured zno lms resulted with thehighestnumberofchargecarriervaluesofaround6.5×1018 1/cm3, but with the lowest mobility with values of around the 0.32 cm2/v·s. the higher the percentage of substrate-covered area of zno lms, the lower their resistivity, regardless of their morphology and texture. the <001> texturized sample c3 resulted with the lowest resistivity of 4.02 ω·cm. the mobility in zno lms resulted mainly inuenced by substrate-covered area, this when its value is less than 95%, while forhighervalues the mobility is dominated by the crystalline grain size. a new optical parameter resulted from the dierence between photoluminescent emissions associated with donor defects (zni0 y zni) and vzn acceptors that could be considered as an indicator of the charge carrier concentration. the greater the dierence, the greatest the concentration of n-type charge carriers. these results encourage the use of high resolution photoluminescence spectroscopy to quantitatively measure the dierence between type “n” and “p” charge carriers in zno. this could place photoluminescence spectroscopy as an optical method for characterizations that until this day are done only via electrical techniques. 5. acknowledgment authors wish to express their gratitude to the national council of science and technology (conacyt) for the master scholarships granted to: c. lópez-esmerio and 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3270– 3272 © 2022 the authors. page 302 of 302 introduction experimental details synthesis characterization results and discussion crystalline structure microstructure electrical properties optical properties implications of morphology, texture, and crystallite size on electrical properties conclusions acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper the relationship of multiset, stirling number, bell number, and catalan number wamiliana1*, attiya yuliana1,2, fitriani1 1department of mathematics, fmipa, universitas lampung, lampung, 35145, indonesia2senior high school 1, gedung tataan, bandar lampung, 35362, indonesia *corresponding author: wamiliana.1963@fmipa.unila.ac.id abstractcatalan numbers is not as famous as fibonacci numbers, however this number has own its beauty and arts. catalan numbers wasdiscovered by ming antu in 1730, however, this numbers is credited to eugene catalan when he was studying parentheses in 1838.catalan numbers mostly occurs in counting or enumeration problems. the catalan numbers can be defined in more than one forms, and the most famous form is cn = 1n+1 ( 2n n ) . in this study we will discuss the multiset construction and the relationship of the results of multiset with stirling, bell, and catalan numbers. keywordscounting, enumeration, multiset, catalan numbers, stirling numbers received: 19 january 2023, accepted: 13 april 2023 https://doi.org/10.26554/sti.2023.8.2.330-337 1. introduction in mathematics, there are many types of sequence of numbers. each sequence has its own definition, uniqueness and benefits. for example, a very famous number sequence, namely the fibonacci number sequence, which has a uniqueness, namely the golden ratio and its benefits have also been widely applied in life. catalan numbers are not as popular as the fibonacci numbers, but this sequence of numbers also has many benefits. catalan numbers are named after the belgian scientist eugene c. catalan based on his work while studying parentheses sequences in 1838. the parentheses in question are sequences that are well formed parentheses (pak, 2014) . in addition to brackets, other forms related to catalan numbers are the triangular forms of the convex polygon (cayley, 1890) . actually in 1730 ming antu had discovered the catalan numbers based on the geometrical models constructed (koshy, 2008) . however, because the results were in china and not known in the western world, catalan was bettern known, and the numbers are called as catalan numbers. this number is unique in that it can be defined in several forms and the most famous form is cn = 1 n+1 ( 2n n ) . the following is the first nine terms of catalan number: 1, 2, 5, 14, 42, 132, 429, 1430, 4862,· · · . not as fibonacci sequence where we can easily predict the nth term if given the (n-1) th and (n-2) th terms using its recursive formula fn = f(n−1)+f(n−2), in catalan sequence to predict the nth term by using recursive formula c(n+1) = c0cn+c1c(n−1)+c2c(n−2)+· · ·+cnc0 is a little bit harder, because we have to know almost all values of the terms. for catalan sequence it is easier to count the nth term by using the explisit formula cn = 1 n+1 ( 2n n ) . the specialty of catalan numbers is that they often appear in different problems with different solutions, but have the same final solution, namely catalan numbers. shapiro (1976) investigated lattice paths in the first quadrant and derive a similar triangle to pascal’s triangle and called it catalan’s triangle because it involves the catalan numbers. other geometric shapes that turn out to form catalan numbers include the combination of the laticce path based on catalan numbers (saračević et al., 2018) , binary tress and triangulation of a convex polygons (koshy, 2008; stojadinovic, 2015). lee and oh (2018) showed that any binomial coefficient can be written as weighted sums along rows of the catalan triangle. ceballos and d’león (2018) investigated a generalization of the catalan objects indexed by a composition of the form s = (s(1), s(2),...,s(a)), which we call a signature, and the object is combinatoric of planar rooted tree. catalan numbers are also used to solve the pill problem (bayer and brandt, 2014) . boyadzhiev (2021) explored a formula for generating various series, including catalan, bernoulli, harmonic, and stirling numbers. a new conservative matrix derived by catalan numbers was investigated by i̇lkhan (2020) . so, actually there are a lot of benefits from the catalan numhttps://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.330-337&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.330-337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 bers themselves. in addition, catalan numbers have also been widely applied in various fields, such as engineering, in computational geometry, geographic information systems, cryptographic geodesy, and medicine (selim and saračević, 2019) . for data security, saračević et al. (2018) investigated the application of catalan numbers and lattice path for cryptography; and saračević et al. (2017) used catalan keys based on dynamic programming for steganography. moreover, in 2019, saračević et al. (2019) continued exploring catalan numbers and dyck word for steganography. (ndagijimana, 2016) investigated the properties and application of catalan number in the rna (ribonucleic acid) secondary structure. for more comprhehensive discussion about catalan number can be found in koshy (2008) and stanley (2015) . one of the problems whose solution is catalan numbers is the problem of catalan numbers in algebra, namely the parker permutation problem (guy, 1993) . in the book catalan numbers and their applications written by t. koshy it was informed that this problem had been answered by ira m. gessel of brandies university, waltham, massachusetts in 1993, by providing a solution in determining the number of multisets with n-elements a1, a2, a3,· · · , an are members of ai∈zn such that a1 + a2 + a3+ · · · + an = is the identity of the sum zn (koshy, 2008) . in this study we will discuss the multisets of group additive zn with 1 ≤ n ≤ 10, and shows the ralations of those multisets with bell numbers, stirling numbers, and catalan numbers. 2. the method 2.1 multiset let s be a non-empty set. a multiset m from a set s is an ordered pair: m = {(si,ni)|si∈s, ni∈ℤ+,𝕫i≠sj for i≠j}, where ℤ+ = {1,2,. . . }, ni is called as the multiplicity of element si in m. if the underlying set is finite, the multiset is called finite. the size of a finite multiset m is defined as the sum of the multiplicities of all of its elements (roman, 2005) . for example, m = {(p,3), (q,1), (r,2)} is a multiset of underlying set s = {p, q, r} in which element p has multiplicity 3, q has multiplicity 1 and r has multiplicity 2. another way to write this multiset is by writing out all elements according the multiplicities, for above example write m as m = {p, p, p, q, r, r}. if x is a set of elements, a multiset a from the set x is represented by a function ca is ca: m→n, where n is the set of non-negative integers. for every x∈x, ca(x) is the characteristic value of x in a and shows how many times the element x appears in a. a multiset a is a set if ca(x) = 0 or 1 for all x (tripathy et al., 2018) . there are a lot of possible permutation of multiset, for example, albert et al. (2001) investigated a permutation of a multiset which do not contain certain ordered patterns of length 3. the following table shows the example of possible multiset with n elements of additive group ℤn+1, 1 ≤ n ≤ 4 (koshy, 2008) . table 1 is the table that shows the number of multisets of group ℤn+1, 1 ≤ n ≤4 where the number of multisets constitute table 1. the number of multisets with n elements of group ℤn+1, 1≤ n ≤ 4 n ℤn+1 multiset with n-elements the number of multisets 1 {0̄, 1̄} 0̄ 1 2 {0̄, 1̄, 2̄} {0̄, 0̄} {1̄, 2̄} 2 3 {0̄, 1̄, 2̄, 3̄} {0̄, 0̄, 0̄} {0̄, 1̄, 3̄} {0̄, 2̄, 2̄} {1̄, 1̄, 2̄} {2̄, 3̄, 3̄} 5 three catalan numbers which are 1, 2 and 5. 2.2 catalan numbers there are some definitions regarding catalan numbers. however, the most famous way of defining catalan numbers is cn = 1 n + 1 ( 2n n ) where n ≥ 0, n ∈ ℤ+ (1) singmaster (1978) gave a mathematical proof that equation (1) can also be written as cn = ( 2n + 1 n ) 2n + 1 (2) table 2. second-kind stirling number, s(n, k) and bell number bn = ∑n k=0s(n,k) n\k 1 2 3 4 5 6 7 8 9 bell’s number 1 1 1 2 1 1 2 3 1 3 1 5 4 1 7 6 1 15 5 1 15 25 10 1 52 6 1 31 90 65 15 1 203 7 1 63 301 350 140 21 1 877 8 1 127 966 1701 1050 266 28 1 4140 9 1 255 3025 7770 6951 2646 462 36 1 21147 2.3 bell numbers a partition of a set s is a collection of non-empty subsets ai ⊆ s, 1 ≤ i ≤ k, such that ∪ki=1ai = s and for every i ≠ j ai∩aj = ∅. bell number bn is the number of partitions of an n-element set and is defined as: bn = ∑n k=0s(n,k). since bn = 1 , then bn+1 =∑n k=0 ( n k ) bk. for example, b2 = 2 because the 2-element set {a, b} can be partitioned in 2 distinct ways: {a, b}, and {{a}, {b}}, and b3 = 5, because there are 5 different partitions of 3-element set {a, b, c} which are: {{a}, {b}, {c}}, {{a,b}, {c}}, {{a,c},{b} {{b, c}, {c}, and {a, b, c}. 2.4 striling numbers stirling numbers appear in a variety of combinatorial situations. stirling numbers are classified into two kinds: stirling numbers of the first kind and stirling numbers of the second kind. © 2023 the authors. page 331 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 table 3. the multiset group ℤn+1 with 1 ≤ n ≤7 n ℤn+1 multiset with n-elements the number of multiset 1 {0̄,0̄} {0̄} 1 2 {0̄,1̄,2̄ } {0̄,0̄} {1̄,2̄} 2 3 {0̄,1̄,2̄,3̄} {0̄,0̄,0̄} {0̄,1̄,3̄} {0̄,2̄,2̄} {1̄,1̄,2̄} {2̄,3̄,3̄} 5 4 {0̄,1̄,2̄,3̄,4̄} {0̄,0̄,1̄,4̄} {0̄,0̄,2̄,3̄} {0̄,1̄,1̄,3̄} {0̄,1̄,2̄,2̄} {0̄,2̄,4̄,4̄} {0̄,3̄,3̄,4̄} {1̄,1̄,1̄,2̄} {1̄,1̄,4̄,4̄} {1̄,2̄,3̄,4̄} {1̄,3̄,3̄,3̄} {2̄,2̄,2̄,4̄} {2̄,2̄,3̄,3̄} {3̄,4̄,4̄,4̄} 14 5 {0̄,1̄,2̄,3̄,4̄,5̄} {0̄,0̄,0̄,0̄,0̄} {0̄,0̄,0̄,0̄,5̄} {0̄,0̄,0̄,2̄,4̄} {0̄,0̄,0̄,3̄,3̄} {0̄,0̄,1̄,1̄,4̄} {0̄,0̄,1̄,2̄,3̄} {0̄,0̄,2̄,2̄,2̄} {0̄,1̄,1̄,1̄,3̄} {0̄,0̄,2̄,5̄,5̄} {0̄,0̄,3̄,4̄,5̄} {0̄,0̄,4̄,4̄,4̄} {0̄,1̄,1̄,2̄,2̄} {0̄,1̄,1̄,5̄,5̄} {0̄,1̄,3̄,3̄,5̄} {0̄,1̄,3̄,4̄,4̄} {0̄,2̄,2̄,4̄,4̄} {0̄,2̄,2̄,3̄,5̄} {0̄,2̄,3̄,3̄,4̄} {0̄,3̄,3̄,3̄,3̄} {1̄,1̄,1̄,1̄,2̄} {1̄,1̄,2̄,4̄,5̄} {1̄,1̄,2̄,3̄,5̄} {1̄,1̄,2̄,4̄,4̄} {1̄,1̄,3̄,3̄,4̄} {1̄,2̄,2̄,2̄,5̄} {1̄,2̄,2̄,3̄,4̄} {1̄,2̄,3̄,3̄,3̄} {1̄,2̄,5̄,5̄,5̄} {1̄,3̄,4̄,5̄,5̄} {1̄,4̄,4̄,4̄,5̄} {0̄,2̄,2̄,2̄,4̄} {2̄,2̄,2̄,3̄,3̄} {2̄,2̄,4̄,5̄,5̄} {2̄,3̄,3̄,5̄,5̄} {2̄,3̄,4̄,4̄,5̄} {2̄,4̄,4̄,4̄,4̄} {3̄,3̄,3̄,4̄,5̄} {3̄,3̄,4̄,4̄,4̄} {4̄,5̄,5̄,5̄,5̄} 42 6 {0̄,1̄,2̄,3̄,4̄,5̄,6̄} {0̄,0̄,0̄,0̄,0̄,0̄} {0̄,0̄,0̄,0̄,1̄,6̄} {0̄,0̄,0̄,0̄,2̄,5̄} {0̄,0̄,0̄,0̄,3̄,4̄} {0̄,0̄,0̄,1̄,1̄,5̄} {0̄,0̄,0̄,1̄,3̄,3̄} {0̄,0̄,0̄,2̄,2̄,3̄} {0̄,0̄,0̄,2̄,6̄,6̄} {0̄,0̄,0̄,3̄,5̄,6̄} {0̄,0̄,0̄,4̄,4̄,6̄} {0̄,0̄,0̄,4̄,5̄,5̄} {0̄,0̄,1̄,1̄,1̄,4̄} {0̄,0̄,1̄,1̄,2̄,3̄} {0̄,0̄,1̄,2̄,2̄,2̄} {0̄,0̄,1̄,1̄,6̄,6̄} {0̄,0̄,1̄,2̄,5̄,6̄} {0̄,0̄,1̄,3̄,4̄,6̄} {0̄,0̄,1̄,3̄,5̄,5̄} {0̄,0̄,1̄,4̄,4̄,5̄} {0̄,0̄,2̄,2̄,4̄,6̄} {0̄,0̄,2̄,2̄,5̄,5̄} {0̄,0̄,2̄,3̄,3̄,6̄} {0̄,0̄,4̄,5̄,6̄,6̄} {0̄,0̄,5̄,5̄,5̄,6̄} {0̄,1̄,1̄,1̄,1̄,3̄} {0̄,1̄,1̄,1̄,2̄,2̄} {0̄,1̄,1̄,1̄,5̄,6̄} {0̄,1̄,1̄,2̄,4̄,6̄} {0̄,1̄,1̄,2̄,5̄,5̄} {0̄,1̄,1̄,3̄,3̄,6̄} {0̄,1̄,1̄,3̄,4̄,5̄} {0̄,1̄,1̄,4̄,4̄,4̄} {0̄,1̄,2̄,2̄,3̄,6̄} {0̄,1̄,2̄,4̄,4̄,5̄} {0̄,1̄,2̄,3̄,3̄,5̄} {0̄,1̄,3̄,2̄,4̄,4̄} {0̄,1̄,2̄,6̄,6̄,6̄} {0̄,1̄,3̄,3̄,3̄,4̄} {0̄,1̄,4̄,4̄,6̄,6̄} {0̄,1̄,4̄,5̄,5̄,6̄} {0̄,1̄,5̄,5̄,5̄,5̄} {0̄,2̄,2̄,2̄,2̄,6̄} {0̄,2̄,2̄,2̄,3̄,5̄} {0̄,2̄,2̄,2̄,4̄,4̄} {0̄,2̄,2̄,3̄,3̄,4̄} {0̄,2̄,3̄,3̄,3̄,3̄} {0̄,2̄,2̄,5̄,6̄,6̄} {0̄,2̄,3̄,4̄,6̄,6̄} {0̄,2̄,3̄,5̄,6̄,6̄} {0̄,2̄,3̄,4̄,6̄,6̄} {0̄,2̄,3̄,5̄,5̄,6̄} {0̄,2̄,4̄,4̄,5̄,6̄} {0̄,3̄,3̄,4̄,5̄,6̄} {0̄,3̄,3̄,5̄,5̄,5̄} {0̄,3̄,4̄,4̄,4̄,6̄} {0̄,3̄,4̄,4̄,5̄,5̄} {0̄,4̄,4̄,4̄,4̄,5̄} {0̄,4̄,6̄,6̄,6̄,6̄} {0̄,5̄,5̄,6̄,6̄,6̄} {1̄,1̄,1̄,1̄,1̄,2̄} {1̄,1̄,1̄,1̄,4̄,6̄} {1̄,1̄,1̄,1̄,5̄,5̄} {1̄,1̄,1̄,2̄,3̄,6̄} {1̄,1̄,1̄,2̄,4̄,5̄} {1̄,1̄,1̄,3̄,4̄,4̄} {1̄,1̄,1̄,3̄,3̄,5̄} {1̄,1̄,1̄,6̄,6̄,6̄} {1̄,1̄,2̄,2̄,2̄,6̄} {1̄,1̄,2̄,2̄,3̄,5̄} {1̄,1̄,2̄,2̄,4̄,4̄} {1̄,1̄,2̄,3̄,3̄,4̄} {1̄,1̄,3̄,3̄,3̄,3̄} {1̄,1̄,2̄,5̄,6̄,6̄} {1̄,1̄,2̄,5̄,5̄,7̄} {1̄,1̄,3̄,4̄,6̄,6̄} {1̄,1̄,3̄,5̄,5̄,6̄} {1̄,1̄,4̄,4̄,5̄,6̄} {1̄,1̄,4̄,5̄,5̄,5̄} {1̄,2̄,2̄,2̄,2̄,5̄} {1̄,2̄,2̄,2̄,3̄,4̄} {1̄,2̄,2̄,3̄,3̄,3̄} {1̄,2̄,2̄,4̄,6̄,6̄} {1̄,2̄,2̄,5̄,5̄,6̄} {1̄,2̄,3̄,3̄,6̄,6̄} {1̄,2̄,3̄,4̄,5̄,6̄} {1̄,2̄,3̄,5̄,5̄,5̄} {1̄,2̄,4̄,4̄,4̄,6̄} {1̄,2̄,4̄,4̄,5̄,5̄} {1̄,2̄,4̄,4̄,4̄,6̄} {1̄,2̄,4̄,4̄,5̄,5̄} {1̄,3̄,3̄,3̄,5̄,6̄} {1̄,2̄,4̄,4̄,5̄,5̄} {1̄,3̄,3̄,4̄,4̄,6̄} {1̄,3̄,3̄,4̄,5̄,5̄} {1̄,3̄,4̄,4̄,4̄,5̄} {1̄,3̄,6̄,6̄,6̄,6̄} {1̄,4̄,5̄,6̄,6̄,6̄} {1̄,5̄,5̄,5̄,6̄,6̄} {2̄,2̄,2̄,2̄,2̄,4̄} {2̄,2̄,2̄,2̄,3̄,3̄} {2̄,2̄,2̄,3̄,6̄,6̄} {2̄,2̄,2̄,4̄,5̄,6̄} {2̄,2̄,2̄,5̄,5̄,5̄} {2̄,2̄,3̄,3̄,5̄,6̄} {2̄,2̄,3̄,4̄,4̄,6̄} {2̄,2̄,3̄,4̄,5̄,5̄} {2̄,2̄,4̄,4̄,4̄,5̄} {2̄,2̄,6̄,6̄,6̄,6̄} {2̄,3̄,3̄,3̄,4̄,6̄} {2̄,3̄,3̄,3̄,5̄,5̄} {2̄,3̄,3̄,4̄,4̄,5̄} {2̄,3̄,4̄,4̄,4̄,4̄} {2̄,3̄,5̄,6̄,6̄,6̄} {2̄,4̄,4̄,6̄,6̄,6̄} {2̄,4̄,5̄,5̄,6̄,6̄} {2̄,5̄,5̄,5̄,5̄,6̄} {3̄,3̄,3̄,3̄,3̄,6̄} {3̄,3̄,3̄,3̄,4̄,5̄} {3̄,3̄,3̄,4̄,4̄,4̄} {3̄,3̄,4̄,6̄,6̄,6̄} {3̄,3̄,5̄,5̄,6̄,6̄} {3̄,4̄,4̄,5̄,6̄,6̄} {3̄,4̄,5̄,5̄,5̄,6̄} {3̄,5̄,5̄,5̄,5̄,5̄} {4̄,4̄,4̄,4̄,6̄,6̄} {4̄,4̄,4̄,5̄,5̄,6̄} {4̄,4̄,5̄,5̄,5̄,5̄} {5̄,6̄,6̄,6̄,6̄,6̄} 132 © 2023 the authors. page 332 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 7 {0̄,1̄,2̄,3̄,4̄,5̄,6̄,7̄} {0̄,0̄,0̄,0̄,0̄,0̄,0̄} {0̄,0̄,0̄,0̄,0̄,1̄,7̄} {0̄,0̄,0̄,0̄,0̄,2̄,6̄} {0̄,0̄,0̄,0̄,0̄,3̄,5̄} {0̄,0̄,0̄,0̄,1̄,2̄,5̄} {0̄,0̄,0̄,0̄,1̄,3̄,4̄} {0̄,0̄,0̄,0̄,2̄,2̄,4̄} {0̄,0̄,0̄,0̄,2̄,3̄,3̄} {0̄,0̄,0̄,0̄,2̄,7̄,7̄} {0̄,0̄,0̄,0̄,3̄,6̄,7̄} {0̄,0̄,0̄,0̄,4̄,5̄,7̄} {0̄,0̄,0̄,0̄,4̄,6̄,6̄} {0̄,0̄,0̄,0̄,5̄,5̄,6̄} {0̄,0̄,0̄,1̄,1̄,1̄,5̄} {0̄,0̄,0̄,1̄,1̄,2̄,4̄} {0̄,0̄,0̄,1̄,1̄,3̄,3̄} {0̄,0̄,0̄,1̄,2̄,2̄,3̄} {0̄,0̄,0̄,2̄,2̄,2̄,2̄} {0̄,0̄,0̄,1̄,1̄,7̄,7̄} {0̄,0̄,0̄,1̄,2̄,6̄,7̄} {0̄,0̄,0̄,1̄,3̄,5̄,7̄} {0̄,0̄,0̄,1̄,3̄,6̄,6̄} {0̄,0̄,0̄,1̄,4̄,4̄,7̄} {0̄,0̄,0̄,1̄,4̄,5̄,6̄} {0̄,0̄,0̄,1̄,5̄,5̄,5̄} {0̄,0̄,0̄,1̄,4̄,4̄,7̄} {0̄,0̄,0̄,1̄,4̄,5̄,6̄} {0̄,0̄,0̄,2̄,3̄,4̄,7̄} {0̄,0̄,0̄,2̄,3̄,5̄,6̄} {0̄,0̄,0̄,2̄,4̄,4̄,6̄} {0̄,0̄,0̄,2̄,4̄,5̄,5̄} {0̄,0̄,0̄,3̄,3̄,3̄,7̄} {0̄,0̄,0̄,3̄,3̄,4̄,6̄} {0̄,0̄,0̄,3̄,3̄,5̄,5̄} {0̄,0̄,0̄,4̄,4̄,4̄,4̄} {0̄,0̄,0̄,4̄,6̄,7̄,7̄} {0̄,0̄,0̄,5̄,5̄,7̄,7̄} {0̄,0̄,0̄,5̄,6̄,6̄,7̄} {0̄,0̄,0̄,6̄,6̄,6̄,6̄} {0̄,0̄,1̄,1̄,1̄,1̄,4̄} {0̄,0̄,1̄,1̄,1̄,2̄,3̄} {0̄,0̄,1̄,1̄,2̄,2̄,2̄} {0̄,0̄,1̄,1̄,1̄,6̄,7̄} {0̄,0̄,1̄,1̄,2̄,5̄,7̄} {0̄,0̄,1̄,1̄,2̄,6̄,6̄} {0̄,0̄,1̄,1̄,3̄,4̄,7̄} {0̄,0̄,1̄,1̄,3̄,5̄,6̄} {0̄,0̄,1̄,1̄,4̄,4̄,6̄} {0̄,0̄,1̄,1̄,4̄,5̄,5̄} {0̄,0̄,1̄,2̄,2̄,4̄,7̄} {0̄,0̄,1̄,2̄,2̄,5̄,6̄} {0̄,0̄,1̄,2̄,3̄,3̄,7̄} {0̄,0̄,1̄,2̄,3̄,4̄,6̄} {0̄,0̄,1̄,2̄,3̄,5̄,5̄} {0̄,0̄,1̄,3̄,3̄,3̄,6̄} {0̄,0̄,1̄,3̄,3̄,5̄,5̄} {0̄,0̄,1̄,3̄,3̄,4̄,5̄} {0̄,0̄,1̄,3̄,4̄,4̄,4̄} {0̄,0̄,1̄,3̄,6̄,7̄,7̄} {0̄,0̄,1̄,4̄,5̄,7̄,7̄} {0̄,0̄,1̄,4̄,6̄,6̄,7̄} {0̄,0̄,1̄,5̄,5̄,6̄,7̄} {0̄,0̄,1̄,5̄,6̄,6̄,6̄} {0̄,0̄,1̄,2̄,7̄,7̄,7̄} {0̄,0̄,1̄,3̄,6̄,7̄,7̄} {0̄,0̄,1̄,4̄,5̄,7̄,7̄} {0̄,0̄,1̄,4̄,6̄,6̄,7̄} {0̄,0̄,1̄,5̄,5̄,6̄,7̄} {0̄,0̄,1̄,5̄,6̄,6̄,6̄} {0̄,0̄,2̄,2̄,2̄,3̄,7̄} {0̄,0̄,2̄,2̄,2̄,4̄,6̄} {0̄,0̄,2̄,2̄,2̄,5̄,5̄} {0̄,0̄,2̄,2̄,3̄,3̄,6̄} {0̄,0̄,2̄,2̄,3̄,4̄,5̄} {0̄,0̄,2̄,2̄,4̄,4̄,4̄} {0̄,0̄,2̄,2̄,6̄,7̄,7̄} {0̄,0̄,2̄,3̄,3̄,3̄,5̄} {0̄,0̄,2̄,3̄,3̄,4̄,4̄} {0̄,0̄,2̄,3̄,5̄,7̄,7̄} {0̄,0̄,2̄,3̄,6̄,6̄,7̄} {0̄,0̄,2̄,4̄,4̄,7̄,7̄} {0̄,0̄,2̄,4̄,5̄,6̄,7̄} {0̄,0̄,2̄,4̄,6̄,6̄,6̄} {0̄,0̄,2̄,5̄,5̄,5̄,7̄} {0̄,0̄,2̄,5̄,5̄,6̄,6̄} {0̄,0̄,3̄,3̄,3̄,3̄,4̄} {0̄,0̄,3̄,3̄,4̄,7̄,7̄} {0̄,0̄,3̄,3̄,5̄,6̄,7̄} {0̄,0̄,3̄,3̄,6̄,6̄,6̄} {0̄,0̄,3̄,4̄,4̄,6̄,7̄} {0̄,0̄,3̄,4̄,5̄,5̄,7̄} {0̄,0̄,3̄,4̄,5̄,6̄,6̄} {0̄,0̄,3̄,5̄,5̄,5̄,6̄} {0̄,0̄,4̄,4̄,4̄,5̄,7̄} {0̄,0̄,4̄,4̄,4̄,6̄,6̄} {0̄,0̄,4̄,4̄,5̄,5̄,6̄} {0̄,0̄,4̄,5̄,5̄,5̄,5̄} {0̄,0̄,4̄,7̄,7̄,7̄,7̄} {0̄,0̄,5̄,6̄,7̄,7̄,7̄} {0̄,0̄,6̄,6̄,6̄,7̄,7̄} {0̄,1̄,1̄,1̄,1̄,1̄,3̄} {0̄,1̄,1̄,1̄,1̄,2̄,2̄} {0̄,1̄,1̄,1̄,1̄,5̄,7̄} {0̄,1̄,1̄,1̄,1̄,6̄,6̄} {0̄,1̄,1̄,1̄,2̄,4̄,7̄} {0̄,1̄,1̄,1̄,2̄,5̄,6̄} {0̄,1̄,1̄,1̄,3̄,3̄,7̄} {0̄,1̄,1̄,1̄,3̄,4̄,6̄} {0̄,1̄,1̄,1̄,3̄,5̄,5̄} {0̄,1̄,1̄,1̄,4̄,4̄,5̄} {0̄,1̄,1̄,1̄,7̄,7̄,7̄} {0̄,1̄,1̄,2̄,2̄,3̄,7̄} {0̄,1̄,1̄,2̄,2̄,4̄,6̄} {0̄,1̄,1̄,2̄,2̄,5̄,5̄} {0̄,1̄,1̄,2̄,3̄,3̄,6̄} {0̄,1̄,1̄,2̄,3̄,4̄,5̄} {0̄,1̄,1̄,2̄,4̄,4̄,4̄} {0̄,1̄,1̄,3̄,3̄,3̄,5̄} {0̄,1̄,1̄,3̄,3̄,4̄,4̄} {0̄,1̄,2̄,2̄,2̄,2̄,7̄} {0̄,1̄,2̄,2̄,2̄,3̄,6̄} {0̄,1̄,2̄,2̄,2̄,4̄,5̄} {0̄,1̄,2̄,2̄,3̄,3̄,5̄} {0̄,1̄,2̄,2̄,3̄,4̄,4̄} {0̄,1̄,2̄,3̄,3̄,3̄,4̄} {0̄,1̄,3̄,3̄,3̄,3̄,3̄} {0̄,1̄,3̄,3̄,3̄,7̄,7̄} {0̄,1̄,3̄,3̄,4̄,6̄,7̄} {0̄,1̄,3̄,3̄,5̄,5̄,7̄} {0̄,1̄,3̄,3̄,5̄,6̄,6̄} {0̄,1̄,3̄,4̄,4̄,5̄,7̄} {0̄,1̄,3̄,4̄,4̄,6̄,6̄} {0̄,1̄,3̄,4̄,5̄,5̄,6̄} {0̄,1̄,3̄,5̄,5̄,5̄,5̄} {0̄,1̄,3̄,7̄,7̄,7̄,7̄} {0̄,1̄,4̄,4̄,4̄,4̄,7̄} {0̄,1̄,4̄,4̄,4̄,5̄,6̄} {0̄,1̄,4̄,4̄,5̄,5̄,5̄} {0̄,1̄,4̄,6̄,7̄,7̄,7̄} {0̄,1̄,5̄,5̄,7̄,7̄,7̄} {0̄,1̄,5̄,6̄,6̄,7̄,7̄} {0̄,1̄,6̄,6̄,6̄,6̄,7̄} {0̄,2̄,2̄,2̄,2̄,2̄,6̄} {0̄,2̄,2̄,2̄,2̄,3̄,5̄} {0̄,2̄,2̄,2̄,2̄,4̄,4̄} {0̄,2̄,2̄,2̄,3̄,3̄,4̄} {0̄,2̄,2̄,2̄,4̄,7̄,7̄} {0̄,2̄,2̄,2̄,5̄,6̄,7̄} {0̄,2̄,2̄,2̄,6̄,6̄,6̄} {0̄,2̄,2̄,3̄,3̄,3̄,3̄} {0̄,2̄,2̄,3̄,3̄,7̄,7̄} {0̄,2̄,2̄,3̄,4̄,6̄,7̄} {0̄,2̄,2̄,3̄,5̄,5̄,7̄} {0̄,2̄,2̄,3̄,5̄,6̄,6̄} {0̄,2̄,2̄,4̄,4̄,5̄,7̄} {0̄,2̄,2̄,4̄,4̄,6̄,6̄} {0̄,2̄,2̄,4̄,5̄,5̄,6̄} {0̄,2̄,2̄,5̄,5̄,5̄,5̄} {0̄,2̄,3̄,3̄,3̄,6̄,7̄} {0̄,2̄,3̄,3̄,4̄,5̄,7̄} {0̄,2̄,3̄,3̄,4̄,6̄,6̄} {0̄,2̄,3̄,3̄,5̄,5̄,6̄} {0̄,2̄,3̄,4̄,4̄,4̄,7̄} {0̄,2̄,3̄,4̄,4̄,5̄,6̄} {0̄,2̄,3̄,4̄,5̄,5̄,5̄} {0̄,2̄,3̄,6̄,7̄,7̄,7̄} {0̄,2̄,4̄,4̄,4̄,4̄,7̄} {0̄,2̄,4̄,4̄,4̄,5̄,6̄} {0̄,2̄,4̄,4̄,5̄,5̄,5̄} {0̄,2̄,4̄,5̄,7̄,7̄,7̄} {0̄,2̄,4̄,6̄,6̄,7̄,7̄} {0̄,2̄,5̄,5̄,6̄,7̄,7̄} {0̄,2̄,5̄,6̄,6̄,6̄,7̄} {0̄,2̄,6̄,6̄,6̄,6̄,6̄} {0̄,3̄,3̄,3̄,3̄,5̄,7̄} {0̄,3̄,3̄,3̄,3̄,6̄,6̄} {0̄,3̄,3̄,3̄,4̄,4̄,7̄} {0̄,3̄,3̄,3̄,4̄,5̄,6̄} {0̄,3̄,3̄,3̄,5̄,5̄,5̄} {0̄,3̄,3̄,4̄,4̄,4̄,6̄} {0̄,3̄,3̄,4̄,4̄,5̄,5̄} {0̄,3̄,3̄,5̄,7̄,7̄,7̄} {0̄,3̄,3̄,6̄,6̄,7̄,7̄} {0̄,3̄,4̄,4̄,4̄,4̄,5̄} {0̄,3̄,4̄,4̄,7̄,7̄,7̄} {0̄,3̄,4̄,5̄,6̄,7̄,7̄} {0̄,3̄,4̄,6̄,6̄,6̄,7̄} {0̄,3̄,5̄,5̄,5̄,7̄,7̄} {0̄,3̄,5̄,5̄,6̄,6̄,7̄} {0̄,3̄,5̄,6̄,6̄,6̄,6̄} {0̄,4̄,4̄,4̄,4̄,4̄,4̄} {0̄,4̄,4̄,4̄,6̄,7̄,7̄} {0̄,4̄,4̄,5̄,5̄,7̄,7̄} {0̄,4̄,4̄,5̄,6̄,6̄,7̄} {0̄,4̄,4̄,6̄,6̄,6̄,6̄} {0̄,4̄,5̄,5̄,5̄,6̄,7̄} {0̄,4̄,5̄,5̄,6̄,6̄,6̄} {0̄,5̄,5̄,5̄,5̄,5̄,7̄} {0̄,5̄,5̄,5̄,5̄,6̄,7̄} {0̄,5̄,5̄,5̄,6̄,6̄,6̄} {0̄,5̄,7̄,7̄,7̄,7̄,7̄} {0̄,6̄,6̄,7̄,7̄,7̄,7̄} {1̄,1̄,1̄,1̄,1̄,2̄,2̄} {1̄,1̄,1̄,1̄,1̄,4̄,7̄} {1̄,1̄,1̄,1̄,1̄,5̄,6̄} {1̄,1̄,1̄,1̄,2̄,3̄,7̄} {1̄,1̄,1̄,1̄,2̄,4̄,6̄} {1̄,1̄,1̄,1̄,2̄,5̄,5̄} {1̄,1̄,1̄,1̄,3̄,3̄,6̄} {1̄,1̄,1̄,1̄,3̄,4̄,5̄} {1̄,1̄,1̄,1̄,4̄,4̄,4̄} {1̄,1̄,1̄,1̄,6̄,7̄,7̄} {1̄,1̄,1̄,2̄,2̄,2̄,7̄} {1̄,1̄,1̄,2̄,2̄,3̄,6̄} {1̄,1̄,1̄,2̄,2̄,4̄,5̄} {1̄,1̄,1̄,2̄,3̄,3̄,5̄} {1̄,1̄,1̄,2̄,3̄,4̄,4̄} {1̄,1̄,1̄,3̄,3̄,3̄,4̄} {1̄,1̄,1̄,2̄,5̄,7̄,7̄} {1̄,1̄,1̄,2̄,6̄,6̄,7̄} 429 © 2023 the authors. page 333 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 {1̄,1̄,1̄,3̄,4̄,7̄,7̄} {1̄,1̄,1̄,3̄,5̄,6̄,7̄} {1̄,1̄,1̄,3̄,6̄,6̄,6̄} {1̄,1̄,1̄,4̄,4̄,6̄,7̄} {1̄,1̄,1̄,4̄,5̄,5̄,7̄} {1̄,1̄,1̄,4̄,5̄,6̄,6̄} {1̄,1̄,1̄,5̄,5̄,5̄,6̄} {1̄,1̄,2̄,2̄,2̄,2̄,6̄} {1̄,1̄,2̄,2̄,2̄,3̄,5̄} {1̄,1̄,2̄,2̄,2̄,4̄,4̄} {1̄,1̄,2̄,2̄,3̄,3̄,4̄} {1̄,1̄,2̄,3̄,3̄,3̄,3̄} {1̄,1̄,2̄,2̄,4̄,7̄,7̄} {1̄,1̄,2̄,2̄,5̄,6̄,7̄} {1̄,1̄,2̄,2̄,6̄,6̄,6̄} {1̄,1̄,2̄,3̄,3̄,7̄,7̄} {1̄,1̄,2̄,3̄,4̄,6̄,7̄} {1̄,1̄,2̄,3̄,5̄,5̄,7̄} {1̄,1̄,2̄,3̄,5̄,6̄,6̄} {1̄,1̄,2̄,4̄,4̄,5̄,7̄} {1̄,1̄,2̄,4̄,4̄,6̄,6̄} {1̄,1̄,2̄,4̄,5̄,5̄,6̄} {1̄,1̄,2̄,5̄,5̄,5̄,5̄} {1̄,1̄,2̄,7̄,7̄,7̄,7̄} {1̄,1̄,3̄,3̄,3̄,6̄,7̄} {1̄,1̄,3̄,3̄,4̄,5̄,7̄} {1̄,1̄,3̄,3̄,4̄,6̄,6̄} {1̄,1̄,3̄,3̄,5̄,5̄,6̄} {1̄,1̄,3̄,4̄,4̄,4̄,7̄} {1̄,1̄,3̄,4̄,4̄,5̄,6̄} {1̄,1̄,3̄,4̄,5̄,5̄,5̄} {1̄,1̄,3̄,6̄,7̄,7̄,7̄} {1̄,1̄,4̄,4̄,4̄,4̄,6̄} {1̄,1̄,4̄,4̄,4̄,5̄,5̄} {1̄,1̄,4̄,5̄,7̄,7̄,7̄} {1̄,1̄,4̄,6̄,6̄,7̄,7̄} {1̄,1̄,5̄,5̄,6̄,7̄,7̄} {1̄,1̄,5̄,6̄,6̄,6̄,7̄} {1̄,1̄,6̄,6̄,6̄,6̄,7̄} {1̄,2̄,2̄,2̄,2̄,3̄,4̄} {1̄,2̄,2̄,2̄,3̄,3̄,3̄} {1̄,3̄,3̄,3̄,3̄,4̄,7̄} {1̄,3̄,3̄,3̄,3̄,5̄,6̄} {1̄,3̄,3̄,3̄,4̄,4̄,6̄} {1̄,3̄,3̄,3̄,4̄,5̄,5̄} {1̄,3̄,3̄,4̄,4̄,4̄,5̄} {1̄,3̄,3̄,4̄,7̄,7̄,7̄} {1̄,3̄,3̄,5̄,6̄,7̄,7̄} {1̄,3̄,3̄,6̄,6̄,6̄,7̄} {1̄,3̄,4̄,4̄,4̄,4̄,4̄} {1̄,3̄,4̄,4̄,6̄,7̄,7̄} {1̄,3̄,4̄,5̄,5̄,7̄,7̄} {1̄,3̄,4̄,5̄,6̄,6̄,7̄} {1̄,3̄,4̄,6̄,6̄,6̄,6̄} {1̄,3̄,5̄,5̄,5̄,6̄,7̄} {1̄,3̄,5̄,5̄,6̄,6̄,6̄} {1̄,4̄,4̄,4̄,5̄,7̄,7̄} {1̄,4̄,4̄,4̄,6̄,6̄,7̄} {1̄,4̄,4̄,5̄,5̄,6̄,7̄} {1̄,4̄,4̄,5̄,6̄,6̄,6̄} {1̄,4̄,5̄,5̄,5̄,5̄,7̄} {1̄,4̄,5̄,5̄,5̄,6̄,6̄} {1̄,5̄,5̄,5̄,5̄,5̄,6̄} {1̄,5̄,6̄,7̄,7̄,7̄,7̄} {1̄,6̄,6̄,6̄,7̄,7̄,7̄} {2̄,2̄,2̄,2̄,2̄,2̄,4̄} {2̄,2̄,2̄,2̄,2̄,3̄,3̄} {2̄,2̄,2̄,2̄,2̄,7̄,7̄} {2̄,2̄,2̄,2̄,3̄,6̄,7̄} {2̄,2̄,2̄,2̄,4̄,5̄,7̄} {2̄,2̄,2̄,2̄,4̄,6̄,6̄} {2̄,2̄,2̄,2̄,5̄,5̄,6̄} {2̄,2̄,2̄,3̄,3̄,6̄,6̄} {2̄,2̄,2̄,3̄,4̄,4̄,7̄} {2̄,2̄,2̄,3̄,4̄,5̄,6̄} {2̄,2̄,2̄,3̄,5̄,5̄,5̄} {2̄,2̄,2̄,4̄,4̄,4̄,6̄} {2̄,2̄,2̄,4̄,4̄,5̄,5̄} {2̄,2̄,2̄,5̄,7̄,7̄,7̄} {2̄,2̄,2̄,6̄,6̄,7̄,7̄} {2̄,2̄,3̄,3̄,3̄,4̄,7̄} {2̄,2̄,3̄,3̄,3̄,5̄,6̄} {2̄,2̄,3̄,3̄,4̄,4̄,6̄} {2̄,2̄,3̄,3̄,4̄,5̄,5̄} {2̄,2̄,3̄,4̄,4̄,4̄,5̄} {2̄,2̄,4̄,4̄,4̄,4̄,4̄} {2̄,3̄,3̄,3̄,3̄,3̄,7̄} {2̄,3̄,3̄,3̄,3̄,4̄,6̄} {2̄,3̄,3̄,3̄,3̄,5̄,5̄} {2̄,3̄,3̄,3̄,4̄,4̄,5̄} {2̄,3̄,3̄,4̄,4̄,4̄,4̄} {2̄,3̄,3̄,3̄,7̄,7̄,7̄} {2̄,3̄,3̄,4̄,6̄,7̄,7̄} {2̄,3̄,3̄,5̄,5̄,7̄,7̄} {2̄,3̄,3̄,5̄,6̄,6̄,7̄} {2̄,3̄,3̄,6̄,6̄,6̄,6̄} {2̄,3̄,4̄,4̄,5̄,7̄,7̄} {2̄,3̄,4̄,4̄,6̄,6̄,7̄} {2̄,3̄,4̄,5̄,5̄,6̄,7̄} {2̄,3̄,4̄,5̄,6̄,6̄,6̄} {2̄,3̄,5̄,5̄,5̄,5̄,7̄} {2̄,3̄,7̄,7̄,7̄,7̄,7̄} {2̄,4̄,4̄,4̄,4̄,7̄,7̄} {2̄,4̄,4̄,4̄,5̄,6̄,7̄} {2̄,4̄,4̄,4̄,6̄,6̄,6̄} {2̄,4̄,4̄,5̄,5̄,5̄,7̄} {2̄,4̄,4̄,5̄,5̄,6̄,6̄} {2̄,4̄,5̄,5̄,5̄,5̄,6̄} {2̄,4̄,6̄,7̄,7̄,7̄,7̄} {2̄,5̄,5̄,5̄,5̄,5̄,5̄} {2̄,5̄,5̄,7̄,7̄,7̄,7̄} {2̄,5̄,6̄,6̄,7̄,7̄,7̄} {2̄,6̄,6̄,6̄,6̄,6̄,7̄} {3̄,3̄,3̄,3̄,3̄,3̄,6̄} {3̄,3̄,3̄,3̄,3̄,4̄,5̄} {3̄,3̄,3̄,3̄,4̄,4̄,4̄} {3̄,3̄,3̄,3̄,6̄,7̄,7̄} {3̄,3̄,3̄,4̄,5̄,7̄,7̄} {3̄,3̄,3̄,4̄,6̄,6̄,7̄} {3̄,3̄,3̄,5̄,5̄,6̄,7̄} {3̄,3̄,3̄,5̄,6̄,6̄,6̄} {3̄,3̄,4̄,4̄,4̄,7̄,7̄} {3̄,3̄,4̄,4̄,5̄,6̄,7̄} {3̄,3̄,4̄,4̄,6̄,6̄,6̄} {3̄,3̄,4̄,5̄,5̄,5̄,7̄} {3̄,3̄,4̄,5̄,5̄,6̄,6̄} {3̄,3̄,5̄,5̄,5̄,5̄,6̄} {3̄,3̄,6̄,7̄,7̄,7̄,7̄} {3̄,4̄,4̄,4̄,4̄,6̄,7̄} {3̄,4̄,4̄,4̄,5̄,5̄,7̄} {3̄,4̄,4̄,4̄,5̄,6̄,6̄} {3̄,4̄,4̄,5̄,5̄,5̄,6̄} {3̄,4̄,5̄,5̄,5̄,5̄,5̄} {3̄,4̄,5̄,7̄,7̄,7̄,7̄} {3̄,4̄,6̄,6̄,7̄,7̄,7̄} {3̄,5̄,5̄,6̄,7̄,7̄,7̄} {3̄,5̄,6̄,6̄,6̄,7̄,7̄} {3̄,6̄,6̄,6̄,6̄,6̄,7̄} {4̄,4̄,4̄,4̄,5̄,5̄,6̄} {4̄,4̄,4̄,5̄,5̄,5̄,5̄} {4̄,4̄,4̄,7̄,7̄,7̄,7̄} {4̄,4̄,5̄,6̄,7̄,7̄,7̄} {4̄,4̄,6̄,6̄,6̄,7̄,7̄} {4̄,5̄,5̄,5̄,7̄,7̄,7̄} {4̄,5̄,5̄,6̄,6̄,7̄,7̄} {4̄,5̄,6̄,6̄,6̄,6̄,7̄} {4̄,6̄,6̄,6̄,6̄,6̄,6̄} {5̄,5̄,5̄,5̄,6̄,7̄,7̄} {5̄,5̄,5̄,6̄,6̄,6̄,7̄} {5̄,5̄,6̄,6̄,6̄,6̄,6̄} © 2023 the authors. page 334 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 table 4. multiset of additive group ℤn+1 with 1 ≤ n ≤ 7 which is the partition of ∑n−1 k=0 p(k(n + 1); n, n) n ℤn+1 k multiset the number of multisets total 1 {0̄,1̄} 0 {0̄} 1 1 2 {0̄,1̄,2̄} 0 {0̄,0̄} 1 2 1 {1̄,2̄} 1 3 {0̄,1̄,2̄,3̄} 0 {0̄,0̄,0̄} 1 1 {0̄,1̄,3̄} {0̄,2̄,2̄} {1̄,1̄,2̄} 3 5 2 {2̄,3̄,3̄} 1 4 {0̄,1̄,2̄,3̄,4̄} 0 {0̄,0̄,0̄,0̄} 1 14 1 {0̄,0̄,1̄,4̄} {0̄,0̄,2̄,3̄} {0̄,1̄,1̄,3̄} {0̄,1̄,2̄,3̄} {1̄,1̄,1̄,2̄} 5 2 {0̄,2̄,4̄,4̄} {0̄,3̄,3̄,4̄} {1̄,1̄,4̄,4̄} {1̄,2̄,3̄,4̄} {1̄,3̄,3̄,3̄} {2̄,2̄,2̄,4̄} {2̄,2̄,3̄,3̄} 7 3 {3̄,4̄,4̄,4̄} 1 5 {0̄,1̄,2̄,3̄,4̄,5̄} 0 {0̄,0̄,0̄,0̄,0̄} 1 181 1 {0̄,0̄,0̄,1̄,5̄} {0̄,0̄,0̄,2̄,4̄} {0̄,0̄,0̄,3̄,3̄} {0̄,0̄,1̄,1̄,4̄} {0̄,0̄,1̄,2̄,3̄} {0̄,0̄,2̄,2̄,2̄} {0̄,1̄,1̄,1̄,3̄} {0̄,1̄,1̄,2̄,2̄} {1̄,1̄,1̄,1̄,2̄} 9 2 {0̄,0̄,2̄,5̄,5̄} {0̄,0̄,3̄,4̄,5̄} {0̄,0̄,4̄,4̄,4̄} {0̄,1̄,1̄,5̄,5̄} {0̄,1̄,2̄,4̄,5̄} {0̄,1̄,3̄,3̄,5̄} {0̄,1̄,3̄,4̄,4̄} {0̄,2̄,2̄,4̄,4̄} {0̄,2̄,2̄,3̄,5̄} {0̄,2̄,3̄,3̄,4̄} {0̄,3̄,3̄,3̄,3̄} {1̄,1̄,1̄,4̄,5̄} {1̄,1̄,2̄,3̄,5̄} {1̄,1̄,2̄,4̄,4̄} {1̄,1̄,3̄,3̄,4̄} {1̄,2̄,2̄,2̄,5̄} {1̄,2̄,2̄,3̄,4̄} {1̄,2̄,3̄,3̄,3̄} {2̄,2̄,2̄,2̄,4̄} {2̄,2̄,2̄,3̄,3̄} 20 3 {0̄,3̄,5̄,5̄,5̄} {0̄,4̄,4̄,5̄,5̄} {1̄,2̄,5̄,5̄,5̄} {1̄,3̄,4̄,5̄,5̄} {1̄,4̄,4̄,4̄,5̄} {2̄,2̄,4̄,5̄,5̄} {2̄,3̄,3̄,5̄,5̄} {2̄,3̄,4̄,4̄,5̄} {2̄,4̄,4̄,4̄,4̄} {3̄,3̄,3̄,4̄,5̄} {3̄,3̄,4̄,4̄,4̄} 11 4 {4̄,5̄,5̄,5̄,5̄} 1 4 {0̄,0̄,4̄,7̄,7̄,7̄,7̄} {0̄,0̄,5̄,6̄,7̄,7̄,7̄} {0̄,0̄,6̄,6̄,6̄,7̄,7̄} {0̄,1̄,3̄,7̄,7̄,7̄,7̄} {0̄,1̄,4̄,6̄,7̄,7̄,7̄} {0̄,1̄,5̄,5̄,7̄,7̄,7̄} {0̄,1̄,5̄,6̄,6̄,7̄,7̄} {0̄,1̄,6̄,6̄,6̄,6̄,7̄} {0̄,2̄,2̄,7̄,7̄,7̄,7̄} {0̄,2̄,3̄,6̄,7̄,7̄,7̄} {0̄,2̄,4̄,5̄,7̄,7̄,7̄} {0̄,2̄,4̄,6̄,6̄,7̄,7̄} {0̄,2̄,5̄,5̄,6̄,7̄,7̄} {0̄,2̄,5̄,6̄,6̄,6̄,7̄} {0̄,2̄,6̄,6̄,6̄,6̄,6̄} {0̄,3̄,3̄,5̄,7̄,7̄,7̄} {0̄,3̄,3̄,6̄,6̄,7̄,7̄} {0̄,3̄,4̄,4̄,7̄,7̄,7̄} {0̄,3̄,4̄,5̄,6̄,7̄,7̄} {0̄,3̄,4̄,6̄,6̄,6̄,7̄} {0̄,3̄,5̄,5̄,5̄,7̄,7̄} {0̄,3̄,5̄,5̄,6̄,6̄,7̄} {0̄,3̄,5̄,6̄,6̄,6̄,6̄} {0̄,4̄,4̄,4̄,6̄,7̄,7̄} {0̄,4̄,4̄,5̄,5̄,7̄,7̄} {0̄,4̄,4̄,5̄,6̄,6̄,7̄} {0̄,4̄,4̄,6̄,6̄,6̄,6̄} {0̄,4̄,5̄,5̄,5̄,6̄,7̄} {0̄,4̄,5̄,5̄,6̄,6̄,6̄} {0̄,5̄,5̄,5̄,5̄,5̄,7̄} {0̄,5̄,5̄,5̄,5̄,6̄,7̄} {0̄,5̄,5̄,5̄,6̄,6̄,6̄} {1̄,1̄,2̄,7̄,7̄,7̄,7̄} {1̄,1̄,3̄,6̄,7̄,7̄,7̄} {1̄,1̄,4̄,5̄,7̄,7̄,7̄} {1̄,1̄,4̄,6̄,6̄,7̄,7̄} {1̄,1̄,5̄,5̄,6̄,7̄,7̄} {1̄,1̄,6̄,6̄,6̄,6̄,7̄} {1̄,2̄,2̄,6̄,7̄,7̄,7̄} {1̄,2̄,3̄,5̄,7̄,7̄,7̄} {1̄,2̄,3̄,6̄,6̄,7̄,7̄} {1̄,2̄,4̄,4̄,7̄,7̄,7̄} {1̄,2̄,4̄,5̄,6̄,7̄,7̄} {1̄,2̄,4̄,6̄,6̄,6̄,7̄} {1̄,2̄,5̄,5̄,5̄,7̄,7̄} {1̄,2̄,5̄,5̄,6̄,6̄,7̄} {1̄,2̄,5̄,6̄,6̄,6̄,6̄} {1̄,3̄,3̄,4̄,7̄,7̄,7̄} {1̄,3̄,3̄,5̄,6̄,7̄,7̄} {1̄,3̄,3̄,6̄,6̄,6̄,7̄} {1̄,3̄,4̄,4̄,6̄,7̄,7̄} {1̄,3̄,4̄,5̄,5̄,7̄,7̄} {1̄,3̄,4̄,5̄,6̄,6̄,7̄} {1̄,3̄,4̄,6̄,6̄,6̄,6̄} {1̄,3̄,5̄,5̄,5̄,6̄,7̄} {1̄,3̄,5̄,5̄,6̄,6̄,6̄} {1̄,4̄,4̄,4̄,5̄,7̄,7̄} {1̄,4̄,4̄,4̄,6̄,6̄,7̄} {1̄,4̄,4̄,5̄,5̄,6̄,7̄} {1̄,4̄,4̄,5̄,6̄,6̄,6̄} {1̄,4̄,5̄,5̄,5̄,5̄,7̄} {1̄,4̄,5̄,5̄,5̄,6̄,6̄} {1̄,5̄,5̄,5̄,5̄,5̄,6̄} {2̄,2̄,2̄,5̄,7̄,7̄,7̄} {2̄,2̄,2̄,6̄,6̄,7̄,7̄} {2̄,2̄,3̄,4̄,7̄,7̄,7̄} {2̄,2̄,3̄,5̄,6̄,7̄,7̄} {2̄,2̄,3̄,6̄,6̄,6̄,7̄} {2̄,2̄,4̄,4̄,6̄,7̄,7̄} {2̄,2̄,4̄,5̄,5̄,7̄,7̄} {2̄,2̄,4̄,5̄,6̄,6̄,7̄} {2̄,2̄,4̄,6̄,6̄,6̄,6̄} {2̄,2̄,5̄,5̄,5̄,6̄,7̄} {2̄,2̄,5̄,5̄,6̄,6̄,6̄} {2̄,3̄,3̄,3̄,7̄,7̄,7̄} {2̄,3̄,3̄,4̄,6̄,7̄,7̄} {2̄,3̄,3̄,5̄,5̄,7̄,7̄} {2̄,3̄,3̄,5̄,6̄,6̄,7̄} {2̄,3̄,3̄,6̄,6̄,6̄,6̄} {2̄,3̄,4̄,4̄,5̄,7̄,7̄} {2̄,3̄,4̄,4̄,6̄,6̄,7̄} {2̄,3̄,4̄,5̄,5̄,6̄,7̄} {2̄,3̄,4̄,5̄,6̄,6̄,6̄} {2̄,3̄,5̄,5̄,5̄,5̄,7̄} {2̄,4̄,4̄,4̄,4̄,7̄,7̄} {2̄,4̄,4̄,4̄,5̄,6̄,7̄} {2̄,4̄,4̄,4̄,6̄,6̄,6̄} {2̄,4̄,4̄,5̄,5̄,5̄,7̄} {2̄,4̄,4̄,5̄,5̄,6̄,6̄} {2̄,4̄,5̄,5̄,5̄,5̄,6̄} {2̄,5̄,5̄,5̄,5̄,5̄,5̄} {3̄,3̄,3̄,3̄,6̄,7̄,7̄} {3̄,3̄,3̄,4̄,5̄,7̄,7̄} {3̄,3̄,3̄,4̄,6̄,6̄,7̄} {3̄,3̄,3̄,5̄,5̄,6̄,7̄} {3̄,3̄,3̄,5̄,6̄,6̄,6̄} 112 © 2023 the authors. page 335 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 {3̄,3̄,4̄,4̄,4̄,7̄,7̄} {3̄,3̄,4̄,4̄,5̄,6̄,7̄} {3̄,3̄,4̄,4̄,6̄,6̄,6̄} {3̄,3̄,4̄,5̄,5̄,5̄,7̄} {3̄,3̄,4̄,5̄,5̄,6̄,6̄} {3̄,3̄,5̄,5̄,5̄,5̄,6̄} {3̄,4̄,4̄,4̄,4̄,6̄,7̄} {3̄,4̄,4̄,4̄,5̄,5̄,7̄} {3̄,4̄,4̄,4̄,5̄,6̄,6̄} {3̄,4̄,4̄,5̄,5̄,5̄,6̄} {3̄,4̄,5̄,5̄,5̄,5̄,5̄} {4̄,4̄,4̄,4̄,4̄,5̄,7̄} {4̄,4̄,4̄,4̄,4̄,6̄,6̄} {4̄,4̄,4̄,4̄,5̄,5̄,6̄} {4̄,4̄,4̄,5̄,5̄,5̄,5̄} 5 {0̄,5̄,7̄,7̄,7̄,7̄,7̄} {0̄,6̄,6̄,7̄,7̄,7̄,7̄} {1̄,4̄,7̄,7̄,7̄,7̄,7̄} {1̄,5̄,6̄,7̄,7̄,7̄,7̄} {1̄,6̄,6̄,6̄,7̄,7̄,7̄} {2̄,3̄,7̄,7̄,7̄,7̄,7̄} {2̄,4̄,6̄,7̄,7̄,7̄,7̄} {2̄,5̄,5̄,7̄,7̄,7̄,7̄} {2̄,5̄,6̄,6̄,7̄,7̄,7̄} {2̄,6̄,6̄,6̄,6̄,6̄,7̄} {3̄,3̄,6̄,7̄,7̄,7̄,7̄} {3̄,4̄,5̄,7̄,7̄,7̄,7̄} {3̄,4̄,6̄,6̄,7̄,7̄,7̄} {3̄,5̄,5̄,6̄,7̄,7̄,7̄} {3̄,5̄,6̄,6̄,6̄,7̄,7̄} {3̄,6̄,6̄,6̄,6̄,6̄,7̄} {4̄,4̄,4̄,7̄,7̄,7̄,7̄} {4̄,4̄,5̄,6̄,7̄,7̄,7̄} {4̄,4̄,6̄,6̄,6̄,7̄,7̄} {4̄,5̄,5̄,5̄,7̄,7̄,7̄} {4̄,5̄,5̄,6̄,6̄,7̄,7̄} {4̄,5̄,6̄,6̄,6̄,6̄,7̄} {4̄,6̄,6̄,6̄,6̄,6̄,6̄} {5̄,5̄,5̄,5̄,6̄,7̄,7̄} {5̄,5̄,5̄,6̄,6̄,6̄,7̄} {5̄,5̄,6̄,6̄,6̄,6̄,6̄} 26 6 {6̄,7̄,7̄,7̄,7̄,7̄,7̄} 1 the stirling number of the first kind c(n, k) is the number of permutations of an n-element set with exactly cycles. secondkind stirling number s(n, k) counts the number of ways that n distinct objects can be partitioned into k indistinguishable subsets, with each subset containing at least one object. according to riordan (2012) , stirling numbers of the first kind is s(n, k), where s(n, k) satisfies the recursion relation s(n, k) = (n-1) s(n−1, k)+ s(n−1, k−1), where k and n are integers, 1 ≤ n ≤ k−1 with initial conditions s(n, 0) = 0, for n ≥ 1 and s(n, n) = 1, for n ≥ 0. table 2 show the relationship of the second-kind stirling number, s(n, k) and bell number bn. the sum of the secondkind stirling number (the sum in every row) is bell number (the number in the last column). 3. results and discussion to determine the number of multisets we can enumerate or use source code. for this study we developed a source code to determine a multiset. the following is an algorithm and the source code for determining all multisets of the additive group ℤn+1 using python. #multiset grup aditif ℤn+1 inisiasi input: n, k, n, k integer output : multisets, number of multiset, multiset for every k and number of multisets for every k. implementation begin read (n, k) set ℤn+1 ← set {0, 1, 2, · · · , n} max k ← (0, 1, 2,· · · , n-1) target (n, k) repeat (n+1)*k until max k candidates←set(combination with raplecement (ℤn+1, max k)); targets ← [target (n, k) for k in max k]; multiset (candidates, targets): for candidate in candidates if (sum(candidate) in targets) then add multiset in candidate repeat multisets until target (n, k) multiset← multiset (candidates, targets); stirling(multisets, targets) for multiset in multisets if (sum(multiset) in targets) then add stirling in multiset repeat stirling until target k2← target (n, k) for k = k input; stirling←stirling (multiset, k2); print("ℤn+1 : ", set ℤn+1) print("k : ", max k) print("multisets : ", multisets) print("bilangan stirling k = ",k,":", stirling) print("jumlah bilangan stirling k = ",k," : ", len(stirling)) print("total bilangan catalan : ", len(multisets)) end the multisets generated by that source code are grouped and put in table 3. from the result of table 3, we do partition p(m;n,n) on the number of multisets, where p(m;n,n) is the number of partitions of m to at most n parts and every element in each part cannot exceed n, with m = k(n+1). thus, the number of multisets can be written as ∑n−1 k=0 p(k(n+1); n, n). the result are shown on table 4. based on the computational results where 0 ≤ k ≤ n-1, a sequence of numbers is obtained, which is contained in table 5 below: based on table 5, many possible multisets are formed from the additive group ℤ10 forming a catalan number for each n. in addition, if the multiset additive group ℤ10 is divided into several parts where each part depends on the value of k(n+1) with 0 ≤ k ≤ n-1, then the number of multisets formed will form a new second type of the stirling number. the stirling number in the left-hand side (in table 5, the yellow row) will © 2023 the authors. page 336 of 337 wamiliana et. al. science and technology indonesia, 8 (2023) 330-337 table 5. number sequences of the possible multiset sums of the additive group ℤ10 k\n 0 1 2 3 4 5 6 7 8 catalan number 1 1 1 2 1 1 2 3 1 3 1 5 4 1 5 7 1 14 5 1 9 20 11 1 42 6 1 13 48 51 18 1 132 7 1 20 100 169 112 26 1 429 8 1 28 194 461 486 221 38 1 1430 9 1 40 352 1128 1667 1210 411 52 1 4862 be smaller, and the rightmost portion (in red ) will be larger than the stirling number of the second type that is known. moreover, the last column which sum of the stirling’s number and originally is bell’s, now was replaced by a catalan number. 4. conclusion we can conclude that the multiset formed from the additive group ℤ10 is a catalan number based on the results. in addition, if the multiset additive group ℤ10 is divided into several parts where each part depends on the value of k(n+1) with 0 ≤ k ≤ n-1, then the number of multisets will form a new stirling number of the second kind. however, the second kind of stirling number formed based on the multiset additive group ℤ10 has a different initial value, namely s(n,0) = 1 and the value s(n,n) = 0. for s(n,1) to s(n,n-2) the value is smaller, while for s(n,n-1) it has a larger value. moreover, the sum of the stirling number and originally is bell number, now is changed to be catalan number. 5. acknowledgment the authors gratefully acknowledge the help and support from 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(2015). on catalan numbers. the teaching of mathematics, 18(1); 16–24 tripathy, b. c., s. debnath, and d. rakshit (2018). on multiset group. proyecciones (antofagasta), 37(3); 479–489 © 2023 the authors. page 337 of 337 introduction the method multiset catalan numbers bell numbers striling numbers results and discussion conclusion acknowledgment research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 3 (2018) 7-13 © 2018 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 31 october 2017; revised 11 january 2018; accepted 11 january 2018 http://doi.org/10.26554/sti.2018.3.1.7-13 antidiabetic activity test of ethanolic seri leave’s (muntingia calabura l.) extract in male rats induced by alloxan 1department of pharmacy, faculty of mathematic and natural sciences, sriwijaya university *corresponding author e-mail: rinaafdil@gmail.com abstract antidiabetic activity test of ethanol extract of seri leave (muntingia calabura l.) rats induced by alloxan has been done. male wistar albino rats are used as animal models which divided into 6 groups, normal group (aquadest), negative control group (na cmc 0,5%), positive control group (glibenclamide0,43 mg/200 g of bw), and 1, 2, and 3 treatment groups (ethanol extract of seri leave 65, 130, dan 260 mg/kg of bw). rats blood glucose level after induced intraperitoneally by alloxan130 mg/kg of bwcan be stated as diabetes when >200 mg/dl. preprandial blood glucose levels are measured using dtn-410-k photometer, on day 0, 5, 10, and 15. the average result of auc0-15 and percentage of decreasing blood glucose level for positive control group are 2732,5 and 37,43%, and 3 treatment groups (65 mg/kg of bw, 130 mg/kg of bw, and 260 mg/kg of bw) 3105 and 28.90%; 2962.5and 32.16%; 2810 and 35.66%. these points indicated that the ethanol extract of seri leave have an antidiabetic activity and there is no significant difference compared with glibenclamide (p<0.05). percentage of blood glucose decrease level the third treatment group so there is no significant difference compared with positive control group. according to the relation between percentages of blood glucose decrease level with dose, value of ed50 of ethanol extract of seri leave is 692.424 mg/kg of bw. keyword:ethanol extract, seri leaves, antidiabetic, alloxan 1. introduction diabetes mellitus (dm) is a metabolic disorder accompanied by hyperglycemia that occurs when the pancreas is unable to produce enough insulin or when the body cannotuse the insulin that is produced effectively (price and wilson, 2005). according to anies (2006), type-1 diabetes is caused by pancreatic beta cell damage due to an autoimmune reaction in a long time so that the body can not produce insulin properly (mrowickam, 2005). the normal pancreas produces 31 units of insulin per day, whereas patients with type 1 diabetes produce only 0-4 units per day, and requires additional insulin from the outside (pulungan and herqutanto, 2009). based on data from the health research, the prevalence of diabetes in indonesia aged 15 years and over 6.9% of the 176 million people, or about 12 million people in indonesia suffer from diabetes (riskesdas, 2013) . of these, 30.4% are already diagnosed with diabetes, and 69.6% of patients with diabetes but have not been diagnosed. riskesdas estimated 2030 patients with dm in indonesia will increase two-fold, or about 21.3 million people (kemenkes ri, 2013). according wijayakusuma (2004), treatment of diabetes can be done medically with oral antidiabetic drugs or insulin injections. but because of the high costs, medical treatment is sometimes difficult to do. dm treatment can also be overcome by traditional medicine by using efficacious medicinal plants. one of the plants that can be used as antidiabetic drugs is the seri plant. seri is a plant (muntingia calabura l.) that belongs to genus muntingiaceae and already known by the public as a medicinal plant, including antidiabetic, gout, hypertension, laxative productive cough, flu, headache, fever, antiseptic, anti-seizure, gastroprotective activity, antioxidant and anti-inflammatory activities (kaneeda et al., 1991; wijoyo, 2004; teak and santoso, 2014; balan t et al., 2015; halim sz et al., 2017). empirically, the series leaves water extract has long been used by the public as antidiabetic drugs. the leaves of this plant contain chemicals known as flavonoids, triterpenoids, tannins, saponins, and glycosides (amiruddin, 2007). based on research conducted by ramdhani (2008), the seri leaves ethanol extract at a dose of 130 mg / kg body weight can lower blood glucose levels in mice due to dm type-2 induced streptozotocin. research conducted by the utama (2011), the group leaves the series ethyl acetate fraction dose of 240 mg / kg proven to lower blood glucose levels in mice induced by alloxan. compounds that have the potential to decrease blood glucose levels because in the ethanol extract of seri leaves contains flavonoids that act as antioxidants to inhibit damage to the islet cells of langerhans in the pancreas by means of regenerating β cells of the pancreas and increases insulin secretion (sondang et al., 2005). seri leaves that used is the old leaves. old seri leaf extract has antioxidant activity much stronger when compared to younger leaves (mintowati et al., 2013). therefore, the research conducted in-vivo test blood glucose lowering alloxan-induced mice using seri leaves extract using herlina et al. 2018 / science & technology indonesia 3 (1) 2018: 7-13 8 70% ethanol. the method of diabetes induction in test animals usesalloxan.diabetogenic substance are destructive selective pancreatic β cells. furthermore, blood glucose levels will be measured by enzymatic methods god-pap (glucose oxidase phenol 4-aminophenazone). this research is expected to provide information about the value of auc (area under the curve) as an important parameter that can be determined antidiabetic percentage reduction in blood glucose levels. 2. experimental section 2.1. chemicals and instrumentation materials used consisted of seri leaves (muntingia calabura l.), wistar strain male rats, 70% ethanol (brataco®), god-pap kit (dialab®), standard glucose (dialab®), alloxan (sigma aldrich®), glibenclamide (indofarma) , distilled water (brataco®), na cmc 0.5% (brataco®), and nacl 0.9% (merck®). the tools used in this research, analytical balance (ohaus®), rotary evaporator (yamato®), tools glass (pyrex and iwaki), equipment maintenance test animals, sonde (moh), the syringe injection (onemed®) photometer dtn-410-k (dialab®), non-edta vacutainer tubes (vaculab®), micro pipette (eppendorf®, labopette®), pipette hematocrit (nesco®), silica gel plate f254 (merck®), and sentrifugator ( iec®). 2.2. preparation of extract seri dry leaves that has been mashed, then extracted by means of 500 grams of powder botanicals are macerated in a glass container protected against sunlight, the first maceration process is done by soaking the powder bulbs use 70% ethanol as much as 3.5 liters and stirred occasionally for 2 x 24 hours. the filtrate is collected and stored maceration results. remaceration performed on the remaining pulp using 70% ethanol, 1.5 liters for 1 x 24 hours. the filtrate obtained was concentrated using a rotary evaporator to obtain a thick extract. 2.3. extract characterization 2.3.1. phytochemical test using reagents identification of the flavonoids compound by reacting 1 ml of extract with ammonia solution in the ratio (1: 5) followed by the addition of hydrochloric acid. positive results were marked by the color orange (sibi et al., 2012). identification of the saponin compound by reacting 1 ml of extract by 2 ml of distilled water. the solution was boiled on a water bath accompanied by vigorous shaking. positive result when the foam formed during one hour (sibi et al., 2012). identification of the tannin compound by reacting with 1 ml of the extract with the addition of 5 ml of distilled water. the solution was boiled on a water bath. after the sample is cooled, it treated with 0.1% fecl3 solution until the resulting blue-black color which showed positive results (sibi et al., 2012). identification of the terpenoid compound by reacting with the liebermann-burchard reagent in a way as much as 2 ml of the extract was treated with a solution of 0.5 ml of chloroform followed by the addition of 0.5 ml of glacial acetic acid and 2 ml of concentrated h2so4. a positive result is indicated by the formation of a brownish or violet ring between two layers (ciulei, 1984). identification of the glycoside compound by reacting 5 ml of the extract with 2 ml of glacial acetic acid followed by addition of 1 ml of concentrated h2so4. positive results were characterized by the formation of brown rings (sibi et al., 2012). identification of the alkaloid compounds by reacting 5 ml of the extract with 5 ml of ammonia in chloroform followed by the addition of 2 n h2so4 and will be formed of two layers. the top layer which acts as a water phase is taken and divided into three test tubes. each test tube was tested using reagents mayer, dragendorff, and wagner. the positive results of each tube characterized by the formation of a white precipitate, sediment deposition orange and brown (astarina et al., 2013). 2.3.2. flavonoids test with thin layer chromatography flavonoid test of the ethanol extract of seri leaves using tlc with splattering seri extract solution on the tlc plate measuring 5 x 1 cm with an upper limit and a lower limit that has been created using a pencil. tlc plates and then eluted with an eluent mixture of ethanol and ethyl acetate (1: 1). tlc plate which was eluted was observed spots on uv lamps 254 and 366 nm, and then sprayed with cerium (iv) sulfate. positive results contain flavonoids if the stain turns into brown or brownish-yellow color when observed with the eye (pratiwi et al., 2013). 2.4. preparation and design of animal test rats were divided into 6 groups. group 1 was only given food and drink as normal controls. group 2, as a negative control, induced by alloxan130 mg/kg of bw,and given 0.5% cmc na solution. group 3 as a positive control induced by alloxan 130 mg/kg of bw and given glibenclamide dose of 0.43 mg/200 gbw. group 4, 5 and 6 induced alloxan 130 mg/kg of bw and given ethanol extract of seri leaves with consecutive doses of 65, 130, and 260 mg/kgbw. 2.4.1. measurement of glucose blood taken by retroorbitalis plexus of veins in the eye using a hematocrit pipette. blood collected at the non-edta vacutainer tube and centrifuged at 2,500 rpm for 20 minutes to obtain serum. measurement of glucose is done by adding 1 ml of god-pap reagent in 10 ml of serum. absorption was measured by using a photometer dtn-410-k at a wavelength of 505 nm (purnamasari et al., 2014). 2.4.2. determination of value area under the curve (auc) changes in blood glucose levels from day 0 (after mice expressed dm) up to day 15 was calculated by the formula auc0-15, according okta and sofia (2013), auc value of blood glucose levels of mice can be calculated using a trapezoid formula according to the following equation, with c as blood glucose levels (mg/dl) and t as time measurements. calculation of decrease in blood glucose levels (dbgl), can be calculated using the formula in accordance with the following equation (kurniawati et al., 2012). herlina et al. 2018 / science & technology indonesia 3 (1) 2018: 7-13 9 the calculation of the effective dose (ed50) can be calculated according to the following equation which is based on the relationship between the percent of blood glucose lowering effects of the extract concentration was analyzed using linear regression. y = a + bx 2.5. data analysis normality that the reduction in blood glucose levels were analyzed using the shapiro-wilk normality test, normal distribution of data if the value of p> 0.05. the data analysis followed by one way anova test to examine differences in some groups sampled by a factor of concentration, if p <0.05 indicates significant differences. 3. result and discussion 3.1. extraction plants simplicia of seri leaves that has powdered 500 g macerated with 70% ethanol. according to voight (1984), 70% ethanol is used as an essence solvent for ethanol 70% very effective in generating an optimal active ingredient and can improve the stability of the drug substance is dissolved. after the extraction by maceration, the liquid extract is thickened by a rotary evaporator. viscous extract obtained from the extraction of as much as 132.28 g with a rendemen yield of 26.42%. from these results showed a large enough rendemen indicating that that the most important substance extracted from botanicals that quite a lot. according prasetyorini et al. (2011), the rendemen may be affected by the extraction method used 3.2. characterization extract description: (+) positive and (-) negative based on the data in table 1, the characterization of the extract performed using reagents shown positive results against flavonoids, saponins, tannins, terpenoids and glycosides, but showed a negative result of the alkaloid. this phytochemical test results together with the results of research that has been done sibi et al. (2012) of the methanol extract of seri leaves that contains flavonoids, saponins, tannins, terpenoids and glycosides. the positive results of the characteristics of the extract by using reagents seen by the change in color, foam formation, and the formation of a layer or ring between two layers of the test solution. identification using thin layer chromatography (tlc) is performed to further confirm the results obtained from using the phytochemical test reagents. tlc method chosen because it only requires a little solvent, the amount of gear a bit, and convenient sample preparation (gandjar and rohman, 2007). the results of tlc flavonoid compounds can be seen in figure 1. based on figure 1, the tlc test results of flavonoid compounds contained in the ethanol extract of seri leaves, the tlc plate which was eluted using eluent ethanol and ethyl acetate in the ratio (1: 1) was sprayed with spotting visible cerium (iv) sulfate. positive results contain flavonoids if the stain is brown or brownish yellow. the brown color is formed due to the cerium (iv) sulfate are h2so4 that is a reductant in damaging the chromophore group of active substances so that the wavelength will be shifted toward the longer that stains become visible to the eye (pratiwi et al., 2013) 3.3. alloxan inducing alloxan used as an inducer in order to test animals used conditioned diabetes mellitus type 1. alloxan can disrupt cell oxidation process due to the expenditure of the mitochondrial calcium ion homeostasis resulting in disturbance that causes the death of pancreatic cells (sharma n and garg v, 2009; mohammed fazil ahmed et al., 2010; verma l et al., 2010; rotimi so et al., 2011; okey a. ojiako et al., 2016; attia es et al., 2017). based on figure 2, the normal group is not induced by alloxan, so that the blood glucose levels remain stable in the normal range is equal to 99 mg/dl. bgl value after induction of negative control group until the third treatment group experienced a significant improvement is 253-298 mg/dl. this indicates that the rats have experienced dm for bgl values> 200 mg/dl. 3.4. antidiabetic activity test table 1. phytochemical test of extract by using reagent secondary metabolite extract flavonoid + saponin + tannin + terpenoid + glycoside + alkaloid (a) (b) (c) figure 1. the chromatograms of flavonoid compound in the ethanol extract of seri leaf (a) under uv light 254 nm, (b) under uv light 366 nm and (c) spryed with cerium (iv) sulfate figure 2. effect of blood glucose levels of rats before and after inducing alloxan herlina et al. 2018 / science & technology indonesia 3 (1) 2018: 7-13 10 after the test mice confirmed dm, hereinafter rats given the treatment for 15 days. blood glucose levels were measured on day 5, 10 and 15 after being treated by using a photometer dtn-410-k at a wavelength of 505 nm and then calculated the average blood glucose levels from day 0 to day 15. based on figure 3, it can be seen that the normal blood glucose levels stable group is in the range of normal blood glucose levels <126 mg/dl. this is because in normal group was not given any treatment other than the provision of feed and water. the negative control group was given 0.5% cmc na solution. cmc na solution is used as a negative control, since na cmc used as suspending the test preparation, so it can be ascertained that the na cmc will not affect the decrease in blood glucose levels of mice (illyyani et al., 2015). in this group mouse blood glucose levels are still in a state of diabetic because giving a solution of na cmc does not have an activity that can lower blood glucose levels, blood glucose levels in the positive control group decreased. this is because glibenclamide at a dose of 0.43 mg/200gbw capable of lowering blood glucose levels. according sukandar et al. (2008) mechanism of action of glibenclamide, which stimulates the secretion of insulin from pancreatic langerhans β cells. membrane depolarization occurs due to the interaction glibenclamide with the atp-sensitive k-channels in the cell membrane β. the effect is the further opening of calcium channels (ca). the opening of the canal will lead to ca 2+ ions enter the cell β would then stimulate the β cells to secrete insulin. another reason glibenclamide election as a positive control that enable the sharing of route of administration is oral treatment, so that the time to achieve a therapeutic effect of the treatment groups can be close to or the same as the positive control group. it is not suitable when the insulin that is used as a positive control, and also in consideration of the price of insulin is relatively expensive. the working mechanism of a class of oral antidiabetic drugs (for diabetes mellitus type-2) the other is not suitable when used as a positive control for type-1 diabetes mellitus. the result is done on the research that has been done ratimanjari (2011) using glibenclamide as a positive control in rats induced by alloxan. the treatment group i, ii and iii (suspension of the ethanol extract of seri leaves of the dose 65 mg / kg of bw, 130 mg / kg of bw, and 260 mg / kg of bw) decreased blood glucose levels significantly. the treatment group which has the effect of lowering blood glucose levels are greatest iii treatment at a dose of 260 mg / kg of bw, followed by treatment group ii at a dose of 130 mg / kg of bw and the treatment group i at a dose of 65 mg / kg of bw. a decrease in blood glucose levels is caused by the ethanol extract of seri leaves of the flavonoids contains that have antidiabetic activity. according sondang et al. (2005), flavonoids have antioxidant properties that can protect beta cell damage from free radicals. antioxidants inhibit damage to the islet cells of langerhans in the pancreas by means of regenerating beta cells of the pancreas and increases insulin secretion (balan t et al., 2015). in addition, flavonoids can restore the sensitivity of insulin receptors on the cells so that the blood glucose down and return to normal (ramdhani, 2008). weighing of the mice before and after treatment was also performed to see the differences. at the time prior to induced, average body weight of rats ranges from 193 to 220 grams (can be seen in table 2). but after induced, the weight of negative control group mice up to the treatment group experienced a decline, except normal group. this is because the normal group was not induced by alloxan, so that the weight remains stable and after 15 days being treated, body weight of rats all test groups had increased, but not significantly. this weight loss occurs due to the inability of the body to provide glucose due to lack of insulin to be burned into energy that the body more use of fatty acids and makes the protein as an energy source, while the normal group of mice were given food and drink plain that he was still able to secrete insulin properly (lehninger, 1982). 3.5 determination value of area under curve (auc) having discovered that the average blood glucose levels, auc0-15 value is then calculated to determine changes in blood glucose levels from day 0 to day 15. auc0-15 data is presented in table 3. changes in blood glucose levels of each treatment group by calculating the area under the curve (auc) at day 0 to day 15 (auc0-15). auc0-15 has value inversely with antidiabetic activity. according chotimah et al. (2008), the lower the auc value of the treatment group, the better the activity in the reduction of blood glucose levels. the greater the percentage decrease in blood glucose levels, then the better antidiabetes activity. based on data from table 3, the normal group had auc015 value of 1380. this is due to the normal group was given no treatment is approved, but only given standard feed and drinking water. negative control group had the highest auc0-15 value is 4367.5. this is due to the negative control group were given a 0.5% solution of na cmc does not have the effect of lowering blood glucose levels. positive control group had an average value of auc0-15 the lowest, followed by treatment group iii, ii and i. having obtained the auc0-15 value, then the calculated percent reduction in blood glucose levels. the greater the percentage decrease in blood glucose levels, the better the antidiabetic activity. based on data from table 4, the normal group is not calculated the percentage reduction in blood glucose levels. this is because the normal group did not decrease blood glucose levels for figure 3. effect of seri leaf extract on blood glucose levels for each group on days 0 to 15 table 2. data on average body weight (bw) rats group before alloxan induced after alloxan induced day 5 day 10 day 15 normal 215 219,3 222.3 226 230 negative control 211 194.7 196 197 212.3 positive control 202.3 186 207.7 205.7 215 treatment i 193 173.7 179.7 187 196.7 treatment ii 220.3 194 199.7 204.7 221.3 treatment iii 209 192 204.7 216.3 227.3 herlina et al. 2018 / science & technology indonesia 3 (1) 2018: 7-13 11 this group were not given treatment is approved, but only given standard feed and drinking water. negative control group had a percentage decrease in blood glucose levels 0%. this is due to the negative control group were given a 0.5% solution of na cmc does not have the effect of lowering blood glucose levels. the positive control group has a percentage decrease in blood glucose levels were highest, followed by treatment group iii, ii treatment, and treatment i. data reduction in blood glucose level seach group has been obtained, then statistically analyzed using spss 23.0. of shapiro wilk normality test results, note that the data reduction of blood glucose levels of each group normally distributed and did not differ significantly (p> 0.05). subsequent analysis of parametric statistical analysis by anova one way with a 95% confidence level. from the results of the parametric statistical analysis by anova one way, it is known that there are significant differences between the groups (p <0.05). data from one way anova analysis a significant difference, then continued test post hoc lsd (least significant differences). from the analysis of lsd post hoc test, it is known that there are no significant differences in blood glucose levels of data reduction the positive control group compared with each treatment group (p> 0.05). but there is a significant difference between the positive control group and the treatment of the normal group and negative control group (p <0.05). based on the results of quantitative analysis using spss version 23.0 above, the effect of decreasing blood glucose levels of mice of glibenclamide (positive control) is better than ethanol extract of seri leaves doses of 65 mg/kgbw, 130 mg/kgbw, and 260 mg/kgbw, but there is no significant difference. all three doses of the extract treatment proven to have the potential to decrease blood glucose levels strain wistar male rats induced by alloxan. decreased glucose levels is the case because in the ethanol extract of seri leaves of the contains flavonoid compounds that can act as an antioxidant that can inhibit damage to the islet cells of langerhans in the pancreas by means of regenerating beta cells of the pancreas and increases insulin secretion (mrowicka m, 2005; sondang et al., 2005; balan t et al., 2015). flavonoids are protective against damage to the insulin-producing beta cells as well as to improve insulin sensitivity (panjuantiningrum, 2010). flavonoids can also prevent diabetes by inhibiting the enzyme alpha glycosidase which serves for the breakdown of carbohydrates. inhibition of this enzyme alpha glycosidase causes delays glucose absorption which in turn will lower blood glucose levels (arjadi and susatyo, 2010). 3.6 effective dose 50 (ed50) ed50 value of the ethanol extract of leaves of the series is determined to find the dose that can cause blood glucose-lowering effect in 50% of individuals (animal studies). ed50 value was calculated by linear regression between the dose and the percent reduction in blood glucose levels (%dbgl). results of the linear regression between the dose and the percent reduction in blood glucose levels can be seen in figure 4. linear equations obtained is y = 0,033x + 27.150 with a correlation coefficient (r) = 0.985. from the obtained equation, ed50 of ethanol extract of seri leaves can be calculated, where y is the percent effective dose (50%) and x is the dose of ethanol extract of seri leaves that can decrease blood glucose levels of mice by 50%. from the calculation, the obtained ed50 of ethanol extracts of seri leaves is 692.424 mg/kg. thus, the dose required to achieve an effective dose for 50% in the reduction of blood glucose levels is 692.424 mg/kgbw. 4. conclusion ethanol extract of seri leaves can give the effect of decreasing blood glucose levels dose 65 mg/kgbw, 130 mg/kgbw, and 260 mg/kgbw by percent decrease in blood glucose levels respectively by 28.90%; 32.16%; and 35.66% and has a value of auc0-15 each group of 3105; 2962,5; and 2810. the effective dose (ed50) of ethanol extracts of seri leaves is 692.424 mg/kgbw. acknowledgment we thank to sriwijaya university for support of this research through “saintek” 2017 with contract number 0568/un9/ pp/2017. references amiruddin, z.z. 2007, free radical scavenging activity of some plant available in malaysia, 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indonesia. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper determination of (+)-catechin and antioxidant activity in faloak (sterculia quadrifida r. br) stem bark infusion audrey gracelia riwu1, jusak nugraha2, djoko agus purwanto3*, erwin astha triyono4 1doctoral program of medical science, faculty of medicine, universitas airlangga, surabaya, 60132 indonesia2department of clinical pathology, faculty of medicine, universitas airlangga, surabaya, 60132, indonesia3department of pharmaceutical sciences, faculty of pharmacy, universitas airlangga, surabaya, 60115, indonesia4department of internal medicine, faculty of medicine, universitas airlangga, surabaya, 60132, indonesia *corresponding author: djokoagus@ff.unair.ac.id abstractoxidative stress is a condition that can damage human cells and tissues and has been linked to a number of illnesses, including cancer,cardiovascular disease, autoimmune disorders, and neurological diseases. oxidative stress conditions can be brought on by pollution,radiation exposure, and an unhealthy lifestyle. antioxidants are substances that can be used to both prevent and treat oxidativestress. this study aimed to identify and quantify (+)-catechin levels and antioxidant activity of the stem bark of sterculia quadrifida r.br extracted by the infusion method, a method similar to traditional medicine processing generally in the community. determinationof (+)-catechin and antioxidant activity of s. quadrifida were evaluated by hplc and dpph assay, respectively. quantification of (+)catechin content by hplc system with wavelength 280 nm and antioxidant activity by spectrophotometry method with wavelength517 nm. the results show that the mean value of (+)-catechin level was 7.786% and the ic50 value of the antioxidant activity was51.5`g/ml having a moderate antioxidant activity category. s. quadrifida stem bark infusion can be utilized as a medication candidatefor the prevention or treatment of a variety of disorders caused by oxidative stress. keywords sterculia quadrifida r. br, faloak, (+)-catechin, antioxidant activity, hplc, dpph received: 30 august 2022, accepted: 9 december 2022 https://doi.org/10.26554/sti.2023.8.1.59-65 1. introduction cancer, cardiovascular disease, autoimmune disorder, and cardiovascular and neurodegenerative disease (i.e alzheimer’s disease and parkinson’s disease) are widely known to have a correlation with oxidative stress. oxidative stress is a condition due to an imbalance between the increase of ros and rns secretion that leads to cell and tissue damage. there are many factors that contribute to this condition like exposure to air pollution, tobacco smoke, ozone, alcohol, cooking (used oil, fat, and smoked meat), and another unhealthy lifestyle. these exogenous substances are metabolized or broken down into free radicals after entering the body through various mechanisms (pizzino et al., 2017). free radicals are substances (atoms, ions, or molecules) that contain one or more unpaired electrons that interfere with or attack nearby electrons in order to form bonds with them, which causes oxidative stress (di meo and venditti, 2020). antioxidants are one strategy for reducing oxidative stress. by giving electrons to free radicals, antioxidants are able to neutralize them and inhibit cellular damage potential due to oxidative stress. antioxidants can be found in both manufactured and natural goods, although generally, natural antioxidants are preferred because they have less of an impact on the body. some sources of natural antioxidants are usually derived from plant materials, such as vegetables, fruits and herbs (nimse and pal, 2015; lourenço et al., 2019). (+)-catechin is one of the naturally occurring antioxidants, a derivative form of catechin compound, which is mostlyfound in woodyplants (yamaji and ichihara, 2012). (+)-catechin is a avonoid-derived avan-3-ols compound that is known to have anticarcinogenic, anti-tumor, antibiotic, and antioxidant activity which makes it essential in treating various diseases (lee et al., 2020; musial et al., 2020). sterculia quadrida r. br (world’s known name: peanut tree/kurrajong; local name in indonesia: faloak) is one of the woody plants that belong to the malvaceae family that can be used as a source of natural antioxidants because it is found to have a variety of secondary metabolites, including avonoids, alkaloids, terpenoids, saponin and phenolic (tenda et al., 2021; https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.59-65&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.59-65 riwu et. al. science and technology indonesia, 8 (2023) 59-65 siswadi et al., 2021). this plant can be found in plentiful supply from queensland (western australia), papua new guinea, timor leste, and indonesia (govaerts et al., 2021; siswadi etal.,2021). thestembarkof trees,whichisprocessedthrough boiling or decoction, is the most widely utilized plant part in indonesia (tenda et al., 2021). traditionalmedicinecanbeutilized in avarietyofways and with dierent types of solvents, but in the community, boiling with water is the approach that is most commonly applied. the process of boiling water is thought to be the simplest and safest one that can be used in regular community life (keskin, 2018; wachtel galor and benzie, 2011). based on the above background, the aim of this study is to determine and quantify (+)-catechin using hplc, followed by antioxidant activity using dpph methods in the infusion of s. quadrida stem bark. for additional. in this study, we also identify the functional group of compounds with ftir spectrophotometry methods. the infusion method is an extraction technique that is similar to the community’s processing technique, which involves heating water. therefore, this study is expected to provide an overview of the (+)-catechin levels and antioxidant activity found in traditional medicines that are processed in a common way in the community. 2. experimental section 2.1 materials s. quadrida stem bark was taken from the tree which grows in the cityof kupang, east nusatenggara, indonesia. determination of these plants was carried out at the indonesian institute of sciences, biological research centre, cibinong, bogor. the determination process was conducted on these plant parts such as seeds, owers, leaves, fruit, and stem bark. the (+)-catechin standard was obtained through sigma aldrich, which was interpreted by the testing services unit of the faculty of pharmacy, airlangga university, indonesia. 2.2 extraction s. quadrida stem bark was extracted using the infusion method in order to represent the traditional method of processing by the community. the stem bark of this plant was gathered, sorted, crushed, and mashed using a blender in quantities of up to 500 grams. aquades solvent was used to dissolve the mashed simplisia, which was then heated at 90°c for 15 minutes. after 15 minutes, the ltrate is retrieved, gathered, and dried using the freeze-drying method to produce up to 16 grams of dry powdered stem bark (azwanida, 2015). 2.3 preparation of samples and standard solutions the powdered s. quadrida stem bark was taken as much as 500 mg and put into a ask with a volume of 50 ml. then added ethanol and water with a ratio of 1: 1 until exactly according to the mark on the ask. the sample then underwent sonication for 15 minutes and was ltered with a nylon membrane of 0.45 microns into the hplc vial and analyzed. a raw stock solution of catechins of 10.4 mg was dissolved in 10 ml of methanol which is then ltered using 0.2 microns of nylon (gottumukkala et al., 2014). 2.4 calibration the standard calibration process was carried out by diluting the catechin stock solution with methanol with a concentration range of 200-1000`l. the standard curve was obtained using the peak area of ve concentrations in ve repeat tests and expressed by a linear-quadratic regression equation gottumukkala et al. (2014). 2.5 ftir analysis fourier-transform infrared spectroscopy (ftir) is a technique used to obtain the infrared spectrum of the absorption or emission of a solid, liquid, or gas. the ftir spectrometer simultaneously collects high-resolution spectra data over a wide spectrum range. ftir method is commonly used to identify the groups present in a compound or group of compounds that describe the identity of the natural product extract under study. therefore, ftir is important to provide an overview of the characteristics of a particular plant extract (pharmawati and wrasiati, 2020). approximately 10 mg of water extract of s. quadrida stem bark was mixed with 100 mg of kbr and packaged into sample pellets and then read by the ftir spectrophotometer (perkin elmer, 1302f6802). the results obtained were analyzed by their functional groups starting from wave numbers 450 cm−1 to 4000 cm−1 (pakkirisamy et al., 2017). 2.6 determination of (+)-catechin the (+)-catechin analysis process is carried out using the hplc agilent 1100 system consistingof aquaternarypump, autosampler dad detector, column compartment, and degasser with mercklichrosper100rp-18,250x4mm,0.5 ` column. the entire analysis process is carried out at a temperature of 25°c with a mobile phase using a solution of acetonitrile (a) and methanol (b) with a gradient of 1.2 ml/minute. the mobile phase is ltered usingnylon 0.2 microns where before using the gas was removed rst. the sample injected into hplc was 20 `l with a wavelength (_) of 280 nm. chromatography peaks are identied by comparing retention times between analytes with standards. quantication was determined by peak integration using external standard methods (roman and solomiia, 2019). 2.7 antioxidant activity the antioxidant activity of the sample was tested using the dpph method with ascorbic acid as a control. s. quadrida stem bark infusion samples and ascorbic acid as standard were dissolved with ethanol solvents and made in several concentrations. each solution is picked as much as 1 ml to be added to 3 ml of dpph solution 40 ppm in ethanol. then the solution is shakenrmlyand let standat roomtemperature for30minutes. then the absorbance was measured using a spectrophotometer at a maximum wavelength (_) of 517 nm. these tests were © 2023 the authors. page 60 of 65 riwu et. al. science and technology indonesia, 8 (2023) 59-65 figure 1. ftir spectrum of s. quadrida stem bark repeated twice. radical scavenging activity is indicated as the presentation of free radical inhibitors by a sample calculated with the formula: dpphscavengingactivity(%) = abscontrol-abssample abscontrol ×100% (1) where abscontrol is the absorbance of the dpph and abssample is the absorbance of the sample. the concentration of the sample and the percent inhibition obtained were plotted on the x and y axis respectively in the linear regression equation y=a+bx. this equation is used to determine the ic50 value of the sample. the ic50 value is the sample concentration that can reduce dpph radicals by 50% of the initial concentration. the ic50 value is obtained from the x value (concentration) after replacing the y value with 50 (50% inhibition). the interpretation of ic50 results is that the lower the absorbance of mixed reactions indicates that the higher the activity of free radicals (allam et al., 2020; sinala et al., 2020). 3. result and discussion 3.1 ftir analysis the functional groups in s. quadrida stem bark extract was predicted by interpreting the infrared absorption spectra. the ftir spectrum result can be seen in figure 1, and the interpretation of the functional group can be seen in table 1. based on the results of ftir analysis, seven compounds were found in the stem bark infusion of s. quadirifda, namely alcohol, poly hydroxyl compound, isothiocyanate, aromatic compound, ketone compound, secondary alcohol, and aromatic phosphates. 3.2 determination of (+)-catechin calibration of the (+)-catechin standard used at concentrations of 200 `l – 1000 `l (208, 416, 624, 832, 1040 ppm) indicates good linearity which means the correlation coecient figure 2. (+)-catechin standard calibration curve of the equation was close to 1 and the calibrations curves lead straight lines with a wide range (gottumukkala et al., 2014; pinto et al., 2017). the (+)-catechin content in the s. quadrida stem bark infusion was calculated using the linear regression equation obtained by the curve that can be seen in figure 2. chromatograms of the identication of the standard solutions and infusions can be seen in figures 3 and 4. the result of the determination of (+)-catechins levels can be seen in table 2. based on the results of the hplc test, it is found that the average result of (+)-catechins found in the infusion of the s. quadrida stem bark is 7.786 % w/w with an rpd of 0.889% (table 2). studies on the quantication of (+)-catechin in the stem bark of s. quadrida have never been done before in previous studies. therefore, the determination of (+)-catechin levels in this study is also a novelty in the exploration of specic compounds in the stem bark of s. quadrda. (+)-catechin is a derivative form of catechin, polyphenols avan-3-ols that belong to the avonoid family. this compound is composed of two aromatic rings and several hydroxyl groups, which are classied into two groups: free catechin and esteried catechins. this compound has a molecular weight of 290.27 g/mol with the molecular formula c15h14o6 (figure 5) (diniyah et al., 2022; shukla et al., 2018). (+)-catechin and other catechin derivatives have been shown to have neuroprotective eects as well as antioxidant, anti-cancer, and antimicrobial (chang and wu, 2011). quantication of (+)-catechin in s. quadrida stem bark has never been done in previous studies. however, several studies regarding the quantication of (+)-catechin in other plants have been carried out. a study conducted by silva et al. (2017) stated that the catechin levels found in the spraydried extract (ethanol 95%) of pimenta pseudocaryophyllus was 5.44%. a study conducted by nurliayana et al. (2016) on the methanol, dichloromethanen, and hexane extracts of uncaria © 2023 the authors. page 61 of 65 riwu et. al. science and technology indonesia, 8 (2023) 59-65 table 1. tir spectrum values and functional groups of s. quadirida stem bark no wave number reference wave functional group phyto-compounds (cm−1) number (cm−1) assignment identied 1 3595 3700-3584 oh stretch alcohol 2 3242 3570-3200 o-h stretch, hydroxy poly hydroxy compound group, h-bonded 3 2063 2140-1990 n=c=s stretch isothiocyanate 4 1759 2000-1650 c-h bend aromatic compound 5 1605 1650-1600 c=o stretching vibration, ketone compound ketone group 6 1118 1150-1085 c-o stretch secondary alcohol 7 899 995-85 p-o-c stretch aromatic phosphates table 2. determination results of (+)-catechin levels and antioxidant activity in s. quadrida stem bark infusion catechin levels antioxidant activity (ic50) mean (% w/w) sd (%) rpd (%) mean (`g/ml) sd (%) rpd (%) 7.786 0.049 0.889 51.5 0.29 0.8 note: sd: standard deviation; rpd: relative percentage dierences figure 3. hplc chromatogram of (+)-catechin standard solution. retention time at 1.812 min. figure 4. chromatogram of (+)-catechin in s. quadrida stem bark infusion © 2023 the authors. page 62 of 65 riwu et. al. science and technology indonesia, 8 (2023) 59-65 figure 5. molecular structure of (+)-catechin (isemura, 2019) gambir (hunter) roxbstembarkwas5.12%,0.92%, respectively, and no catechins were found in the hexane extract. based on the two studies above, it can be said that the dierences in catechin levels found were caused by dierences in plant species and solvents used in each study. a study conducted by koch et al. (2018) showed that the levels of (+)-catechin in black tea, green tea, and white tea products from kenyan germplasm were 0.30%, 0.39%, and 0.57%, respectively. meanwhile, in green tea products from china and japan germplasms were 0.13% and 0.12%. based on these results, it was found that (+)-catechin levels in tea products were found to be lower when compared to (+)-catechin levels in s. quadrida stem bark infusion. this is a reasonable, because, in tea, the levelof (+)-catechinhas the lowest levelwhencompared to other catechins (koch et al., 2018; singh et al., 2011). catechins are the most abundant polyphenols in tea which account for 70-80% of the total polyphenols. there are four types of catechins that are most dominant in tea, namely (-)-epicatechin (ec), (-)-epigallocatechin (egc), (-)-epicatechin-3-o-gallate (ecg), and (-)-epigallocatechin -3-o-gallate (egcg), where of the four types of catechins, the concentration of egcgdominates as much as 50-80% of the total catechins (koch et al., 2018; sivanesan et al., 2022). therefore, further studies are needed to identify the total catechins in the stem bark of s. quadrida so that further comparisons can be made. 3.3 antioxidant activity results from the dpph assay using the spectrophotometry method of s. quadrida stem bark infusion can be seen in table 1. the test also was done by replicating twice because both of the results were very close to each other. the dierences in antioxidantactivitybetweens.quadridastembarkandascorbic figure 6. dierences of antioxidant activity between s. quadrida stem bark infusion and ascorbic acid as a control acid can be seen in figure 6. based on the ic50 value, antioxidant activity is divided into ve categories, namely very strong (<10 `g/ml), strong (10-50 `g/ml), moderately (50-100 `g/ml), and weak (100250 `g/ml), and inactive (> 250 `g/ml) (roy and dutta, 2021). this shows that the lowertheic50value, thehigherthe antioxidant activity. according to the classication, s. quadrida stembarkinfusionisclassiedinthemoderatecategorybecause the ic50 value is 51.5 `g/ml, while ascorbic acid, which has an ic50 value of 11.6 `g/ml is classied in the strong category (figure 6). this is presumably because the stem bark of s. quadrida contains a variety of compounds compared to ascorbic acid which is a pure compound. the antioxidant activity of s. quadrida stem bark has been reported in several previous studies. research conducted by (saragih and siswadi, 2019) on ethanol extract found ic50 values from various parts of s. quadrida bark (branch bark, root bark, old regrown bark, new regrown bark, non-striped stem bark) are all below 50 `g/ml, and studies conducted by dillak et al. (2019) on ethanol extract also obtained ic50 values of 14.17 `g/ml. this is thought to be due to dierent typesof solvents, where theextractionprocessusingethanol solvents is the best method of knowing antioxidant activity when compared to water solvents (hidalgo and almajano, 2017). the extraction method also has an impact on antioxidant activity. high-temperature extraction methods have the potential to degrade some of the most controllable molecules that aect antioxidant activity. infusion methods with high temperatures reaching 90°c can have an impact on the outcome since, in general, heating induces a quick initiation reaction and reduces antioxidant activity (xu et al., 2017; réblová, 2012). according to a study done in réblová (2012), there is a linkage between rising temperatures and decreased antioxidant activ© 2023 the authors. page 63 of 65 riwu et. al. science and technology indonesia, 8 (2023) 59-65 ity. antioxidant activity of the easily oxidized antioxidants was decreased at higher temperatures compared to lower temperatures caused by a reduction in the ability of antioxidants to interact with free radicals. catechin levels and antioxidant activity are basically related. catechins are able to counteract free radicals by giving an electron from the phenolic oh group which can reduce free radicals (bernatoniene and kopustinskiene, 2018). catechins can also reduce oxidation by playing a role in chelating and binding metal ions which can start the oxidation process (nain et al., 2022). catechins and antioxidants have a relationship with each other, where the higher the concentration of catechins, the higher the level of antioxidants (lee et al., 2014; musial et al., 2020; bartoszek et al., 2018). however, both of them are also inuenced by various factors, such as the extraction process, the type of solution, temperature, and the concentration of other compounds in it (saklar et al., 2015; hidalgo and almajano, 2017). due to the high-temperature extraction method, and the type of solution used in this investigation, it was discovered that the catechin levels and antioxidant activity were dierent (depending on the type of plant and solvent) than in the prior study. nevertheless, extraction with infusion method is seen as being safer, more practical, and more accessible to the community. 4. conclusion (+)-catechin has been detected and quantied in s. quadrida stem bark infusion with a level of 7.786%. a moderate level of antioxidant activity in this plant’s stem bark was also discovered in this study, with an ic50 value of 51.5 `g/ml. these ndings provide a brief overview of the (+)-catechin content and antioxidantactivityofs.quadridastembarkwhich is processed by the infusion method which is common in the community. therefore, s. quadrida can be utilized as a medication candidate for the prevention or treatment of a variety of disorders caused by oxidative stress. 5. acknowledgment this work is part of the doctoral program dissertation of the faculty of medicine, airlangga university, indonesia. the author thanked the doctoral program of the faculty of medicine and the testing laboratory unit of the faculty of pharmacy, airlangga university, indonesia who had given permission and provided places and facilities for this research. references allam, h., m. bennaceur, r. ksouri, r. sahki, a. marouf, and h. benamar (2020). identication of phenolic compounds and assessment of the antioxidant and antibacterial properties of thymelaea microphylla coss. et dur. from western algerian sahara (ain-sefra province). jordan journal of pharmaceutical sciences, 13(3); 363–377 azwanida, n. 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in chemical defense against damping o fungi of current year fagus crenata seedlings in natural forest. forest pathology, 42(1); 1–7 © 2023 the authors. page 65 of 65 introduction experimental section materials extraction preparation of samples and standard solutions calibration ftir analysis determination of (+)-catechin antioxidant activity result and discussion ftir analysis determination of (+)-catechin antioxidant activity conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 7, no. 4, october 2022 research paper greedy reduction algorithm as the heuristic approach in determining the temporary waste disposal sites in sukarami sub-district, palembang, indonesia sisca octarina1,2, fitri maya puspita2*, siti suzlin supadi3, nur attina eliza2 1mathematics and natural sciences doctoral study, sriwijaya university, indralaya, 30662, indonesia2mathematics department, faculty of mathematics and natural sciences, sriwijaya university, indralaya, 30662, indonesia3institute of mathematical sciences, university of malaya, kuala lumpur, 50603, malaysia *corresponding author: fitrimayapuspita@unsri.ac.id abstractwaste is one of the problems in palembang, indonesia. the amount of waste in palembang increases proportionally to the populationyearly and can adversely affect the community. therefore, we determine the optimal temporary waste disposal site (twds) tooptimize the problems. the set covering model is the proper model for solving the location and allocation problem. in this study, dataon the distance between each twds is needed in the set covering modeling. the novelty in this research is developing the 𝜌-medianproblem model, which is formed from the optimal solution of the set covering location problem (sclp) model. palembang consistsof 18 sub-districts, of which the sukarami sub-district has the highest population density. this study discussed the determination ofstrategic twds in the sukarami sub-district using the sclp model, the 𝜌-median problem, and a heuristic approach, namely thegreedy reduction algorithm in solving the model. based on the solution of the 𝜌-median problem model with lingo 18.0 and the 𝜌-median problem solved by the greedy reduction algorithm, only three strategic twds were found for the sukarami sub-district.the study results recommend a review of the existing twds and particularly the addition of a twds in sukodadi and talang betutuvillages, respectively. keywordstwds location, set covering location problem, 𝜌-median problem, greedy reduction algorithm received: 4 july 2022, accepted: 4 october 2022 https://doi.org/10.26554/sti.2022.7.4.469-480 1. introduction palembang is the second-largest and most populous city on the sumatera island after medan and indonesia’s ninth most populous city. according to the central statistics agency, in 2020, palembang had around 8.5 million people with a population density of 92 people/km2 and 18 sub-districts. sukarami sub-district is one of the sub-districts in palembang, which has crowded public places daily, such as hajj dormitory, km 5 market, pasaraya, hotels, and automotive companies or dealers. the waste volume increases every day. the increase in waste impacts the environment and public health (puspita et al., 2018). waste is an object that is no longer useful and arises from the community environment in solid form, both organic and inorganic. waste can come from markets, factories, ofces, institutions, public buildings, community settlements, or community yards (bangun et al., 2022). the waste is collected in dierent temporary waste disposal sites (twds) in their respective locations (yuliza et al., 2020). according to data from the environment and hygiene service of palembang city, twds are divided into several types: market twds, container twds, self-help twds, and unocial twds. market twds is located in the market area, usually in a concrete square tub. container twds is found in market areas and sometimes around community settlements, usually in bre containers. self-help twds is located in residential areas such as complexes, schools, buildings, or public places, usually in a concrete square tub. unocial twds is generally located in community residential areas in front of the market, which are placed illegally. the waste collected at the twds will then be transported by dump truck to the nal disposal site (fds) in stages according to the transportation schedule from each twds, which is dierent in each region. several factors hinder the transportation process, including the waste transportation routes with longdistances between twds and disordered, the transportation equipment capacity, and the waste volume at each twds (octarina et al., 2022b). in dealing with these problems, the set covering problem (scp) model can be used to nd solutions to this twds optimization problem (octarina et al., 2022b). https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.469-480&amp;domain=pdf https://doi.org/10.26554/sti.2022.7.4.469-480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 set covering is part of integer linear programming related to optimization, which concerns the location-allocation problems and aims to minimize the factors that aect the constraints in the model (sitepu et al., 2022). scp is one optimization problemincomputerscience (crawfordetal.,2018). thescp application in daily life determines the waste vehicles routes, vehicle routes to pick up bus passengers at bus stops, scheduling ight crews, resource allocation, etc (çalık and fortz, 2019; cubillos and wøhlk, 2021; roshanaei et al., 2017; šarac et al., 2016). according to the model group, the scp consists of the set covering location problem (sclp), maximal covering location problem (mclp), 𝜌-median problem, and 𝜌-center problem (octarina et al., 2022a). the four models have a relationship in their solutions but dier in their objective functions. sclp nds the optimum number of twds to serve all demand points (jeong, 2017). mclp aims to maximize the demand by a limited number of twds that can be served in standard time and p-median problem minimizes the distance between twds and sorts the routes (guzmán et al., 2016). the 𝜌-center problem is the min-max multi-centre problem (du et al., 2020). previous research on scp has been carried out (crawford et al., 2018; bangun et al., 2022; çalık and fortz, 2019; daskin and maass, 2019; ahmadi-javid et al., 2017; kinsht and petrunko, 2020; kwon et al., 2020; sitepu et al., 2019; xu and li, 2018). a greedy reduction algorithm (gra) is an algorithm to solve optimization problems such as optimizing facility locations, scheduling employee assignments, and scheduling lectures (ardeshiri et al., 2015). in solving problems, gra performs solutions based on a step-by-step solution in sequence so that the nal solution can be the most optimal (binev et al., 2018). the advantage of gra compared to other algorithms is that it can nd the best route in optimizing the distance, minimize costs, and optimize the facility allocation point (shao et al., 2020). previous research by puspita et al. (2018) used the gra in optimizing twds and found a solution, namely 3 twds, to meet the six villages demands. ardeshiri et al. (2015) implemented the gra for mixtures of exponential families and found the optimal solution, even with a limited computational budget, can provide signicant results of 1%. čertíková et al. (2020) concluded that greedy reduced basis algorithms could shorten the time and provide signicant solutions. this study determines the optimal twds in sukarami sub-district using the scp model and solved by gra. this research’s novelty is in improving the 𝜌-median problem model from the optimal solution of the sclp model. the model and algorithm are expected to optimize the number of twds to meet all demand points in the sub-district. the exact solutions obtained from scp and the heuristic solution using gra are expected to provide the best solution and can be considered for palembang city in determining strategic twds in the sukarami sub-district. 2. experimental section 2.1 methods we discussed the method used in this research in this section. we also briey discuss sclp, the 𝜌-median problem, and a short description of the gra. the steps of this research are listed as follows: 1. collectdataontwdsnames, locations, andthenumber of twds in each village in the sukarami sub-district from the palembang city environment and hygiene service (dlhk palembang). 2. describe the data used, namely: a. check twds location points according to the actual twds location. b. measure the distance between twds and twds and between twds and the village in the sukarami sub-district using google maps. 3. dene variables and parameters for the sclp model and 𝜌-median problem. 4. formulate the set covering model, namely the sclp model and the 𝜌-median problem. 5. find solutions to the sclp model and 𝜌-median problem using the lingo 18.0. application 6. solve the 𝜌-median problem model and implement the gra to solve the 𝜌-median problem model. 7. recapitulate the calculation results of the sclp model and the 𝜌-median problem. 8. analyze the results of the sclp, 𝜌-median problem, and the gra. 9. make conclusions 2.2 set covering location problem (sclp) sclpis one of the optimization problems to nd the optimum twds placements so that it can serve all demand points on the waste transportation distribution system (octarina et al., 2022a). the sclp model can be systematically written as follows: minimize zsclp = ∑︁ j𝜖  xj (1) subject to∑︁ j𝜖 j xj ≥ 1, ∀j𝜖 j (2) xj𝜖 {0,1}, ∀j𝜖 j (3) whereas zsclp = the number of twds location j = the set of twds location with index j the decision variables are: © 2022 the authors. page 470 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 xj = { 1; if the twds is allocated at jth location 0; if the twds is not allocated at j-th location the objective function 1 minimizes the number of twds locations. constraint 2 ensures that at least one twds can meet each demand point and constraint 3 is the binary constraint. 2.3 𝜌-median problem the 𝜌-median problem nds 𝜌 twds at location j to minimize the distance (ahmadi-javid et al., 2017). the 𝜌-median problem can be formulated as follows: minimize zp−median = ∑︁ i𝜖i ∑︁ j𝜖 j di jxi j (4) subject to:∑︁ i𝜖 j xi j = 1, ∀i𝜖i (5)∑︁ i𝜖  yj = p (6) xi j ≤ yi , ∀i𝜖i , ∀j𝜖 j (7) yj𝜖 {0,1}, ∀j𝜖 j (8) xi j𝜖 {0,1}, ∀i𝜖i , ∀j𝜖 j (9) whereas z𝜌−median =the total of minimum distance from the demand point to the twds i =the set of demand point with index i j =the set of twds location with index j p =the number of twds for facility allocation di j =the distance between the i-th and the j-th location (metre) the decision variables are: yj = { 1; if the twds is allocated at j-th location 0; if the twds is not allocated at j-th location xi j = { 1; if the twds is allocated at j-th location 0; if the twds is not allocated at j-th location equation4obtains theminimumdistancefromthedemand point to the nearest facility twds. whereas, constraint 5 indicates the demand for each twds placement. constraint 6 sets the maximum number of twds. constraint 7 suggests thateverytwdsplacementshouldbegiventhesamefacilities, and constraints 8 and 9 indicate that the problem is a binary integer. 2.4 greedy reduction algorithm (gra) gra is an algorithm commonly used to solve optimization problems, determining the optimal facility point. several factors in optimizing the location include the distance between the facility locations and the location quality. gra is an algorithm used to solve optimization problems sequentially, producing a local optimum at each step and producing the best nal solution in a global optimum solution (sanchez-oro and duarte, 2018). according to muliyadi (2017), the greedyalgorithm has several important elements, the candidate set, solution set, selection function, feasibility function, and objective function. in this study, we implemented gra to solve the 𝜌-median problem in getting the nal solution. the steps of gra are as follow: 1. form a distance matrix d with size m×n. 2. look for the dominating matrix value in all existing matrix columns, provided that the dominating column has a smaller value than the other column values or dik ≤ dil; ∀ i≠ k and ∀ i ≠ l. 3. compare all columns with the dominant value from the selected column. 4. find the optimum value by comparing the entry values between the selected dominant column. 5. compare the selected dominant column pair with each column to looks for the optimum value. 6. analyze the results of each step and recapitulate the results. 3. result and discussion twds data in the sukarami sub-district was obtained from dlhk palembang, which was surveyed and grouped based on the twds location points in each village. table 1 shows the distribution of twds based on village location points. there is only one twds in talang jambe village, twds talang jambe, next to public cemetery. kebun bunga village has 6 twds and sukarami has 8 twds. suka bangun, suka jaya, sukodadi, and talang betutu villages do not have any twds. next, the denition of variables for sclp and the 𝜌-median problem model can be seen in table 2. the distance between each twds was obtained through direct measurements of the location with google maps. table 3 states the distance between each twds (di j) in the sukarami sub-district (in meters). the number labelled in yellow is the maximum distance between each twds based on dlhk palembang provisions, which is less than 500 meters. table 3 states that the distance from twds kolonel h burlian beside hotel de premium (x1) to twds naskah (x2) is 610 meters, and so on. using the data in tables 2 and 3, we formulate the sclp model. minimize zsclp =x1 + x2 + x3 + x4 + x5 + x6 + x7 + x8+ x9 + x10 + x11 + x12 + x13 + x14 + x15 (10) subject to © 2022 the authors. page 471 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 1. twds based on village location points no village names twds names 1 talang jambe twds talang jambe next to public cemetery 2 kebun bunga • twds letjen harun sohar in front of honda dealer • twds letjen harun sohar in front of hajj dormitory • twds letjen harun sohar in front of al-hikmah mosque • twds letjen harun sohar in front of talang kedondong • twds letjen harun sohar in front of auto 2000 taa • twds bambu kuning arah rumah sakit pelabuhan 3 sukarami • twds batujajar • twds naskah • twds kolonel h burlian behind mitra bangunan bus stop • twds kolonel h burlian beside lorong dharma agung • twds kolonel h burlian simpang smp 40 palembang • twds kolonel h burlian beside hotel de premium • twds kolonel h burlian in front of bank bri • twds kolonel h burlian beside indomaret bus stop 4 suka bangun 5 suka jaya 6 sukodadi 7 talang betutu x1 ≥ 1 (11) x2 + x4 ≥ 1 (12) x3 ≥ 1 (13) x3 + x4 + x5 ≥ 1 (14) x4 + x5 + x6 ≥ 1 (15) x5 + x6 ≥ 1 (16) x7 + x8 ≥ 1 (17) x9 + x10 ≥ 1 (18) x11 ≥ 1 (19) x12 + x13 ≥ 1 (20) x14 ≥ 1 (21) x15 ≥ 1 (22) x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15𝜖 {0,1} (23) model 10 states that the objective function minimizes the number of twds to satisfy all demand points. constraints (11) to (22) state that each twds must meet at least one request point. constraint (23) states that the variables x1 to x(15) are binary. the optimal solution of the model is attached in table 4. table 2. the denition of variabless variable the denition of variables x1 twds kolonel h burlian beside hotel de premium x2 twds naskah x3 twds batujajar x4 twds kolonel h burlian beside lorong dharma agung x5 twds kolonel h burlian simpang smpn 40 palembang x6 twds kolonel h burlian behind mitra bangunan bus stop x7 twds kolonel h burlian beside indomaret bus stop x8 twds kolonel h burlian in front of bank bri x9 twds letjen harun sohar in front of hajj dormitory x10 twds letjen harun sohar in front of al-hikmah mosque x11 twds letjen harun sohar in front of talang kedondong x12 twds letjen harun sohar in front of honda dealer x13 twds letjen harun sohar auto 2000 taa x14 twds bambu kuning arah rumah sakit pelabuhan x15 twds talang jambe next to public cemetery y1 talang jambe village y2 kebun bunga village y3 sukarami village y4 suka bangun village y5 suka jaya village y6 sukodadi village y7 talang betutu village table 4 states the optimal solution of the model using lingo 18.0 software. in the solver status section, the model class is pilp(pure integerlinearprogramming), which means the model is solved in pilp form. state means the resulting solution is globally optimal. the infeasibility of the model is 0. iterations in the model are 0, meaning that the solution value has been obtained without iteration in programming. the extended solver status section shows that the method used in this case is the branch and bound. the objective value is 10, which means that the optimal number of locations in the model is ten facility locations. generated memory used (gmu) is 22k, meaning the total memory allocation used is 22k. elapsed runtime (er) shows the total time to complete the model on lingo 18.0, 2 seconds. the optimal variable values of the sclp model are attached in table 5. variables with 0 value mean that there are no facilities placed at the location, and variables with one value mean that there are facilities placed at the location. in table 5, it can be seen that there are ten variables with one value, namely the variables x1, x3, x4, x6, x8, x10, x11, x13, x14, x15 which means that the candidate locations should be in 10 twds locations, as shown in table 6. the distance between twds and villages in the sukarami sub-district can be seen in table 7. d11 shows that the distance between jambe village and twds kolonel h burlian beside hoteldepremiumis7,400meters, d13 showsthat thedistance between jambe village and twds batujajar is 5,800 meters, and so on. based on the data in table 7, the 𝜌-median problem model is minimize © 2022 the authors. page 472 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 3. the distance between each twds i\ j di j 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 0 610 2090 750 940 1330 2205 2330 3280 3360 4230 5010 5290 6490 7170 2 610 0 1480 380 570 960 1980 1960 2910 2990 3860 4640 4920 6120 6800 3 2090 1480 0 1850 2040 2430 3200 3430 4380 4460 5330 6110 6390 7590 8270 4 750 380 1850 0 190 580 1600 1580 2530 2610 3480 4260 4540 5740 6420 5 940 570 2040 190 0 390 1410 1390 2340 2420 3290 4070 4350 5550 6230 6 1330 960 2430 580 390 0 1020 1000 1950 2030 2900 3680 3960 5160 5840 7 2205 1980 3200 1600 1410 1020 0 200 1070 1150 2020 2800 3030 4230 4910 8 2330 1960 3430 1580 1390 1000 200 0 950 1030 1900 2680 2960 4160 4840 9 3280 2910 4380 2530 2340 1950 1070 950 0 80 950 1730 2010 3210 3890 10 3360 2990 4460 2610 2420 2030 1150 1030 80 0 870 1650 1930 3130 3810 11 4230 3860 5330 3480 3290 2900 2020 1900 950 870 0 780 1060 2260 2940 12 5010 4640 6110 4260 4070 3680 2800 2680 1730 1650 780 0 280 1480 2160 13 5290 4920 6390 4540 4350 3960 3030 2960 2010 1930 1060 280 0 1200 1880 14 6490 6120 7590 5740 5550 5160 4230 4160 3210 3130 2260 1480 1200 0 1230 15 7170 6800 8270 6420 6230 5840 4910 4840 3890 3810 2940 2160 1880 1230 0 table 4. optimal solution of sclp model solver status model class pilp state global optimal objective 10 infeasibility 0 iterations 0 extended solver status solver type branch and bound best objective 10 objective bound 10 steps 0 active 0 update interval 2 gmu (k) 22 er (sec) 2 table 5. variable value of sclp model variable value variable value variable value x1 1 x6 1 x11 1 x2 0 x7 0 x12 0 x3 1 x8 1 x13 1 x4 1 x9 0 x14 1 x5 0 x10 1 x15 1 table 6. twds candidate locations variable name of twds x1 twds kolonel h burlian beside hotel de premium x3 twds batujajar x4 twds kolonel h burlian beside lorong dharma agung x6 twds kolonel h burlian behind mitra bangunan bus stop x8 twds kolonel h burlian in front of bank bri x10 twds kolonel h burlian in front of bank bri x11 twds letjen harun sohar in front of talang kedondong x13 twds letjen harun sohar in front of auto 2000 taa x14 twds bambu kuning arah rumah sakit pelabuhan x15 twds talang jambe next to public cemetery © 2022 the authors. page 473 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 7. the distance between twds and villages i\j di j 1 3 4 6 8 10 11 13 14 15 1 7400 5800 5900 6500 5500 4200 3600 3100 1900 1320 2 3200 2400 2410 2000 1000 4200 1510 1900 3300 3680 3 1700 1900 900 500 950 2300 3050 3800 5200 5580 4 1800 2800 2400 2900 4000 5300 6150 5400 6800 7280 5 1100 1600 1500 1900 3000 4300 4750 4100 5500 5820 6 5600 6000 4900 4400 3400 3800 4050 4900 6300 6780 7 10000 8400 9500 9100 8000 6700 6050 5800 4900 3980 zp−median =7400y11 + 5800y13 + 5900y14 + 6500y16+ 5500y18 + 4200y110 + 3600y111 + 3100y113+ 1900y114 + 1320y115 + 3200y21 + 2400y23+ 2410y24 + 2000y26 + 1000y28 + 900y210+ 1510y211 + 1900y213 + 3300y214 + 3680y215+ 1700y31 + 1900y33 + 900y34 + 500y36 + 950y38+ 2300y310 + 3050y311 + 3800y313 + 5200y314+ 5580y315 + 1800y41 + 2800y43 + 2400y44+ 2900y46 + 4000y48 + 5300y410 + 6150y411+ 5400y413 + 6800y414 + 7280y415 + 1100y51+ 1600y53 + 1500y54 + 1900y56 + 3000y58+ 4300y510 + 4750y511 + 4100y513 + 5500y514 + 5820y515 + 5600y61 + 6000y63 + 4900y64+ 4400y66 + 3400y68 + 3800y610 + 4050y611+ 4900y613 + 6300y614 + 6780y615 + 10000y71+ 8400y73 + 9500y74 + 9100y76 + 8000y78+ 6700y710 + 6050y711 + 5800y713 + 4900y714+ 3980y715 (24) subject to y11 + y13 + y14 + y16 + y18 + y110 + y111 + y113+ y114 + y115 = 1 (25) y21 + y23 + y24 + y26 + y28 + y210 + y211 + y213+ y214 + y215 = 1 (26) y31 + y33 + y34 + y36 + y38 + y310 + y311 + y313+ y314 + y315 = 1 (27) y41 + y43 + y44 + y46 + y48 + y410 + y411 + y413+ y414 + y415 = 1 (28) y51 + y53 + y54 + y56 + y58 + y510 + y511 + y513+ y514 + y515 = 1 (29) y61 + y63 + y64 + y66 + y68 + y610 + y611 + y613+ y614 + y615 = 1 (30) y71 + y73 + y74 + y76 + y78 + y710 + y711 + y713+ y714 + y715 = 1 (31) x1 + x3 + x4 + x6 + x8 + x10 + x11 + x13 + x14+ x15 = 10 (32) y11, y21, y31, y41, y51, y61, y71 ≤ x1 (33) y13, y23, y33, y43, y53, y63, y73 ≤ x3 (34) y14, y24, y34, y44, y54, y64, y74 ≤ x4 (35) y16, y26, y36, y46, y56, y66, y76 ≤ x6 (36) y18, y28, y38, y48, y58, y68, y78 ≤ x8 (37) y110, y210, y310, y410, y510, y610, y710 ≤ x10 (38) y111, y211, y311, y411, y511, y611, y711 ≤ x11 (39) y113, y213, y313, y413, y513, y613, y713 ≤ x13 (40) y114, y214, y314, y414, y514, y614, y714 ≤ x14 (41) y115, y215, y315, y415, y515, y615, y715 ≤ x15 (42) y11, y21, y31, y41, y51, y61, y71, y13, y23, y33 y43, y53, y63, y73, y14, y24, y34, y44, y54, y64, y74, y16, y26, y36, y46, y56, y66, y76, y18, y28, y38, y48, y58, y68, y78, y110, y210, y310, y410, y510, y610, y710, y111, y211, y311, y411, y511, y611, y711, y113, y213, y313, y413, y513, y613, y713, y114, y214, y314, y414, y514, y614, y714, y115, y215, y315, y415, y515, y615, y715𝜖 {0,1} (43) x1, x3, x4, x6, x8, x10, x11, x13, x14, x15𝜖 {0.1} (44) model 24 minimizes the distance between the village and twds, constraints 25 31 are the limitation of demand points ineachvillage, andconstraint32states that thenumbers of facility locations are 10 locations. constraints 33 to 42 are limitations for location requests. constraints 43 ensure that the variable limitation for village and twds are non-negative and integer. the solution of the model obtained using the lingo 18.0 software is attached in table 8. table 8 in the extended solver status section shows the method used in this case is the branch and bound method. the objective value obtained is 13000. gmu is 53k, which means the amount of memory allocation used is 53k. er shows the total time used to complete the model on lingo 18.0, 2 seconds. the optimal solutions are y115=y210=y36= y41= y51=y68=y715=1 which mean 1. the demand in talang jambe village (y1) is located at © 2022 the authors. page 474 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 8. optimal solutions of 𝜌-median problem model solver status model class pilp state global optimal objective 13000 infeasibility 0 iterations 0 extended solver status solver type branch and bound best objective 13000 objective bound 13000 steps 0 active 0 update interval 2 gmu (k) 53 er (sec) 2 twds talang jambe next to public cemetery (x15) 2. the demand in kebun bunga village (y2) is located at twds letjen harun sohar infront of al-hikmah mosque (x10) 3. the demand in sukarami villag (y3) is located at twds kolonel h burlian behind mitra bangunan bus stop (x6) 4. the demand in suka bangun village (y4) is located at twds kolonel h burlian beside hotel de premium (x1) 5. the demand in suka jaya villagex (y5) is located at twds kolonel h burlian beside hotel de premium (x1) 6. thedemandinsukodadivillage (y6) is locatedattwds kolonel h burlian in front of bank bri (x8) 7. the demand in talang betutu village (y7) is located at twds talang jambe next to public cemetery (x15) the twds obtained from the 𝜌-median problem model is solved by gra in the next stage. the steps of gra are as follows: step 1: d =  7400 5800 5900 6500 5500 4200 3600 3100 1900 1320 3200 2400 2410 2000 1000 900 1510 1900 3300 3680 1700 1900 900 500 950 2300 3050 3800 5200 5580 1800 2800 2400 2900 4000 5300 6150 5400 6800 7280 1100 1600 1500 1900 3000 4300 4750 4100 5500 5820 5600 6000 4900 4400 3400 3800 4050 4900 66300 6780 10000 8400 9500 8000 6700 6050 5800 4900 3980  determine the distance matrix d between villages and twds in the sukarami sub-district. step 2 : compare matrix columns to get the dominating column by comparing each entry in the matrix column. column 1 7400 3200 1700 1800 1100 5600 10000  column 3 5800 2400 1900 2800 1600 6000 8400  compare the matrix column 1 with the matrix column 3. the matrix column 1 is the column with the dominant value because column 1 has more dominant values than column 3. column 3 5800 2400 1900 2800 1600 6000 8400  column 4 5900 2410 900 2400 1500 4900 8500  compare the matrix column 3 with the matrix column 4. the matrix column 4 is the column with the dominant value because column 4 has more dominant values than column 3. the column comparison continues until the comparison of columns 1 and 15. based on the results of the column comparison, it is found that columns 8, 10, and 11 are more dominant than other columns. thus, columns 8, 10, and 11 are solutions for the 𝜌-median model. step 3: compare each column entry with the dominating result column, nd, and add the smallest dominant value. comparison with column 8 column 1 and 8 7400 3200 1700 1800 1100 5600 10000   5500 1000 950 4000 3000 3400 8000  −→ we add the smallest dominant value from each row of column 1 and 8, so 5500+1000+950+1800+1100+3400+ 8000=21750 column 3 and 8 5800 2400 1900 2800 1600 6000 8400   5500 1000 950 4000 3000 3400 8000  −→ we add the smallest dominant value from each row of column 3 and 8, so 5500+1000+950+2800 +1600+3400+ 8000= 23250 thecomparisoncontinuesuntil thecomparisonofcolumns 15 and 8. the dominant results from comparing each column with matrix column 8 are attached in table 9. © 2022 the authors. page 475 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 9. the dominant results from comparing each column with matrix column 8 column 1 3 4 6 10 11 13 14 15 8 21,750 23,250 22,700 23,200 23,150 22,510 21,250 19,150 17,650 based on table 9, the minimum value of the comparison between columns 8 and 1 is 21,750. the minimum value of the comparison between columns 8 and 3 is 23,250 and continues until the minimum value of columns 8 and 15. the least value is in column 15, as the solution of facility location (8,15). comparison with column 10 column 1 and 10 7400 3200 1700 1800 1100 5600 10000   4200 900 230 5300 4300 3800 6700  −→ we add the smallest dominant value from each row of column 1 and 10, so 4200+900+1700+1800 +1100+3800 +6700=20200 column 3 and 10 5800 2400 1900 2800 1600 6000 2400   4200 900 2300 5300 4300 3800 6700  −→ we add the smallest dominant value from each row of column 3 and 10, so 4200+900+1900+2800+1600+ +3800+6700=21900 thecomparisoncontinuesuntil thecomparisonofcolumns 15 and 10. the dominant results from comparingeach column with matrix column 10 are attached in table 10. based on table 10, the minimum value of the comparison between columns 10 and 1 is 20,200. the minimum value of the comparison between columns 10 and 3 is 21,900 and continues until the minimum value of columns 10 and 15. the least value is in column 1, as the solution of facility location (10,1). step 4 : compare the selected dominant column pair with each column and nd the optimum value. for pairs of columns (8,15) with columns 1,3,4,6,10,11,13,14 column (8,15) with column 1  5500 1000 950 4000 3000 3400 8000   1320 3680 5580 7280 5820 6780 3980   7400 3200 1700 1800 1100 5600 10000  −→ we add the smallest dominant value from each row of column 8,15, and 1, so 1320+ 1000+950+1800 +1100 +3400+3980= 13550 column (8,15) with column 3  5500 1000 950 4000 3000 3400 8000   1320 3680 5580 7280 5820 6780 3980   5800 2400 1900 2800 1600 6000 8400  −→ we add the smallest dominant value from each row of column 8,15, and 3, so 1320+1000 +950+2800 +1600+3400 +3980= 15050 thecomparisoncontinuesuntil thecomparisonofcolumns (8,15) and 14. the dominant results from comparing each column with matrix column (8,15) are attached in table 11. figure 1. the strategic twds in sukarami sub-district based on table 11, the minimum value of the comparison between columns (8,15) and 1 is 13,550. the minimum value of the comparison between columns (8,15) and 3 is 15,050 and continues until the minimum value of columns (8,15) and 14. the least value is in column 1, as the solution of facility location (8,15,1). for pairs of columns (8,15,1) with columns 3,4,6,10,11,13, © 2022 the authors. page 476 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 10. the dominant results from comparing each column with matrix column 10 column 1 3 4 6 8 11 13 14 15 10 20,200 21,900 20,400 20,900 23,150 26,250 25,300 23,400 21,900 table 11. the dominant results from comparing each column with matrix column (8,15) column 1 3 4 6 10 11 13 14 (8,15) 3,550 15,050 14,500 15,000 17,550 17,650 17,650 17,650 14 column (8,15,1) with column 3  5500 1000 950 4000 3000 3400 8000   1320 3680 5580 7280 5820 6780 3980   7400 3200 1700 1800 1100 5600 10000   5800 2400 1900 2800 1600 6000 8400  −→ we add the smallest dominant value from each row of column 8,15, 1 and 3, so 1320+1000+ 950+1800 +1100+3400 +3980= 13550 column (8,15,1) with column 4  5500 1000 950 4000 3000 3400 8000   1320 3680 5580 7280 5820 6780 3980   7400 3200 1700 1800 1100 5600 10000   5900 2410 900 2400 1500 4900 9500  −→ we add the smallest dominant value from each row of column 8,15, 1 and 4, so 1320+1000+900+1800+ 1100+3400+3980= 13550 thecomparisoncontinuesuntil thecomparisonofcolumns (8,15,1) and 14. the dominant results from comparing each column with matrix column (8,15,1) are attached in table 12. based on table 12, the minimum value of the comparison between columns (8,15,1) and 3 is 13,550. the minimum value of the comparison between columns (8,15,1) and 4 is 13,550 and continues until the minimum value of columns (8,15,1) and 14. the least value is in column 6 which is 13,100. for pairs of columns (10,1) with columns 3,4,6,8,11,13,14, 15 column (10,1) with column 3  4200 900 2300 5300 4300 3800 6700   7400 3200 1700 1800 1100 5600 10000   5800 2400 2400 1900 2800 1600 6000  −→ we add the smallest dominant value from each row of column 8,1, and 3, so 14200 +900+1700+1800 +1100+3800+6700 = 20200 column (10,1) with column 4  4200 900 2300 5300 4300 3800 6700   7400 3200 1700 1800 1100 5600 10000   5900 2410 900 2400 1500 4900 9500  −→ we add the smallest dominant value from each row of column 8,1, and 4, so 4200+ 900+9001800+1100+ 3800+6700= 19400 thecomparisoncontinuesuntil thecomparisonofcolumns (10,1) and 15. the dominant results from comparing each column with matrix column (10,1) are attached in table 13. based on table 13, the minimum value of the comparison between columns (10,1) and 3 is 20,200. the minimum value of the comparison between columns (10,1) and 4 is 19,400 and continues until the minimum value of columns (10,1) and 15. the least value is in column 15 which is 14,600. step 5 : analyze the results of each step. based on steps 1 to 4, it is found that the completion of the rst pair of columns is 8,15,1,6 and the second pair of columns is 10,1,15 with the following explanation: 1. 8 is matrix column 8, which shows twds kolonel h burlian in front of bank bri. 2. 15 is matrix column 15, which shows twds talang jambe next to public cemetery. 3. 1 is matrix column 1, which shows twds kolonel h burlian beside hotel de premium. 4. 6 is matrix column 6, which shows twds kolonel h burlian behind mitra bangunan bus stop. 5. 10 is matrix column 10, which shows twds letjen harun sohar in front of al-hikmah mosque. 6. 1 is matrix column 1, which shows twds kolonel h burlian beside hotel de premium. 7. 15 is matrix column 15, which shows twds letjen harun sohar in front of auto 2000 taa. the solution of the 𝜌-median problem model that gra solved is shown in table 14. based on table 14, the demand in talang jambe village will be located at twds kolonel h burlian in front of bank bri. the demand in kebun bunga village will be located at twds talang jambe next to public cemetery, and so on. the comparisons of 𝜌-median calculation results using lingo 18.0 software and gra are shown in table 15. based on the comparison of the calculation results from © 2022 the authors. page 477 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 12. the dominant results from comparing each column with matrix column (8,15,1) column 3 4 6 10 11 13 14 (8,15,1) 13,550 13,550 13,100 13,450 13,550 13,550 13,550 table 13. the dominant results from comparing each column with matrix column (10,1) column 3 4 6 8 11 13 14 15 (10,1) 20,200 19,400 19,000 19,050 18,950 18,200 16,100 14,600 table14. the solution of the 𝜌-median problem model using gra no village solution of gra 1 talang jambe twds kolonel h burlian in front of bank bri 2 kebun bunga twds talang jambe next to public cemetery 3 sukarami twds kolonel h burlian beside hotel de premium 4 suka bangun twds kolonel h burlian behind mitra bangunan bus stop 5 suka jaya twds letjen harun sohar infront of alhikmah mosque 6 sukodadi twds kolonel h burlian beside hotel de premium 7 talang betutu twds letjen harun sohar in front of auto 2000 taa table 15. the comparisons of 𝜌-median solution using lingo 18.0 software and gra no demand recommended twds locations lingo 18.0 gra 1 talang jambe village twds talang jambe next to public cemetery twds kolonel h burlian in front of bank bri 2 kebun bunga village twds letjen harun sohar in front of alhikmah mosque twds talang jambe next to public cemetery 3 sukarami village twds kolonel h burlian behind mitra bangunan bus stop twds kolonel h burlian beside hotel de premium 4 suka bangun village twds kolonel h burlian beside hotel de premium twds kolonel h burlian behind mitra bangunan bus stop 5 suka jaya village twds kolonel h burlian beside hotel de premium twds letjen harun sohar in front of alhikmah mosque 6 sukodadi village twds kolonel h burlian in front of bank bri twds kolonel h burlian beside hotel de premium 7 talang betutu village twds talang jambe next to public cemetery twds letjen harun sohar in front of auto 2000 taa © 2022 the authors. page 478 of 480 octarina et. al. science and technology indonesia, 7 (2022) 469-480 table 15 with table 1, it turns out that there is a discrepancy between the demand in each village and the specied twds. according to lingo solutions, the appropriate twds for talang jambe village should be placed at twds talang jambe next to public cemetery. whereas, based on the gra, the appropriate twds is twds kolonel h burlian in front of bank bri. dierences in solutions also occur in other villages. by analyzing the optimal solution from lingo 18.0, gra, and the current locations of twds, this research recommends the strategic twds as follows. 1. twds talang jambe next to public cemetery will serve the demand in talang jambe village. 2. twdsletjenharunsoharinfrontofal-hikmahmosque will serve the demand in kebun bunga and suka jaya village. 3. twds kolonel h burlian beside hotel de premium will serve the demand in sukarami and suka bangun village. 4. we recommend to add some new twds in sukodadi and talang betutu village. 4. conclusion from the results and discussion, we only got three strategic twdsinthesukaramisub-district. byanalyzing theoptimal solution from lingo 18.0, gra, and the current locations of twds, this research recommends tdws talang jambe next to public cemetery, twds kolonel h burlian in front of bank bri, twds letjen harun sohar in front of al-hikmah mosque, twds letjen harun soharauto 2000 taa, twds kolonel h burlian behind mitra bangunan bus stop, and twds kolonel h burlian beside hotel de premium. we also recommended adding some new twds in sukodadi and talang betutu villages because no twds is serving these two villages now. the strategic twds can be seen in figure 1. we can use other heuristic approaches for further research and add additional 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(2022). facility location problem of dynamic optimal location of hospital emergency department in palembang. science and technology indonesia, 7(2); 251–256 sitepu, r., f. m. puspita, s. romelda, a. fikri, b. susanto, and h. kaban (2019). set covering models in optimizing the emergency unit location of health facility in palembang. in journal of physics: conference series, volume 1282. iop publishing, page 012008 xu, f. and j. li (2018). ahybrid encoded memetic algorithm for set covering problem. in tenth international conference on advanced computational intelligence (icaci). ieee, pages 552–557 yuliza, e., f. m. puspita, and s. s. supadi (2020). the robust counterpart open capacitated vehicle routing problem with time windows on waste transport problems. bulletin of electrical engineering and informatics, 9(5); 2074–2081 © 2022 the authors. page 480 of 480 introduction experimental section methods set covering location problem (sclp) -median problem greedy reduction algorithm (gra) result and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper facile fabrication of layered double hydroxide-lignin for efficient adsorption of malachite green neza rahayu palapa1*, nur ahmad2,3, alfan wijaya3, zaqiya artha zahara3 1department of chemistry, faculty of mathematics and natural sciences, universitas sriwijaya, ogan ilir 30662, indonesia2graduate school, faculty of mathematics and natural sciences, sriwijaya university, ogan ilir, 30662, indonesia3research center of inorganic materials and complexes, faculty of mathematics and natural sciences, sriwijaya university, palembang, 30139, indonesia *corresponding author: nezarahayu@gmail.com abstractpreparation of layered double hydroxide-lignin (lignin-zn/al) carried out by coprecipitation method. the ftir spectra of lignin-zn/aldisplayed at 3448, 2939, 1620, 1381, 1118, 1041, and 601 cm−1. the characteristic peaks are located at 10.1°, 19.1°, 20.1°, 29.4°, 33.9°,and 60.4°. the lignin-zn/al nitrogen adsorption-desorption isotherm showed a type-iv curve, indicating that it had a mesoporousstructure. the h3 kind of hysteresis loop also provides evidence for the presence of mesopores within the lignin-zn/al complex.lignin-zn/al, lignin, and zn/al had phpzc values of 6.09, 3.01, and 6.09, respectively. lignin-zn/al, lignin, and zn/al are positivelycharged when the ph of the solution is less than phpzc, and they are negatively charged when the ph of the solution is more thanphpzc. the langmuir and pseudo-second-order model best represented the mg adsorption onto all adsorbents. the lignin-zn/al,lignin, and zn/al were shown to have maximum langmuir adsorption capacities of 83.034, 78.740, and 36.364 mg/g, respectively.zn/al adsorption capacity increased 2.28 times after being composited with lignin. keywordslayered double hydroxide, adsorption, lignin, malachite green received: 20 january 2023, accepted: 8 april 2023 https://doi.org/10.26554/sti.2023.8.2.305-311 1. introduction the contamination brought on by the wastewater discharge of organic dyes has become a more prominent issue because of the industry’s rapid development (tang et al., 2022) . in many industries, including papers, tannery, printing inks, clothing, and others, dyes are widely utilized. as a result, a lot of colorful wastewater is produced, and many organic dyes will have a major harmful impact on the environment and human health (giri et al., 2022; vigneshwaran et al., 2021). malachite green (mg), a triphenylmethane cationic dye, is frequently used in the textile industry (jin et al., 2022) . however, even at low concentrations, mg has been discovered to have numerous toxicological side effects on human bodies, such as mutagenic, teratogenic, and cancerous consequences (buvaneswari and singanan, 2022; sarkar et al., 2021). several cutting-edge methods, such as extraction (raval et al., 2022) , photodegradation (puthukkara et al., 2022) , membranes (iqbal et al., 2022) , oxidation combining ultrasonic and electrochemical (ren et al., 2021) , and adsorption (moradi and panahandeh, 2022) , have been used to remove mg from aqueous medium over the past few decades. adsorption has garnered the most attention among these due to its straightforward functioning, design flexibility, practical recyclability, and excellent reliability. for the purpose of removing mg from an aqueous solution, numerous sophisticated adsorption materials have been developed recently, including costus woodsonii (van tran et al., 2022) , modified metal-organic frameworks (dahlan et al., 2023) , biowaste garlic peel (pathania et al., 2022) , and layered double hydroxide (ahmad et al., 2023a) . layered double hydroxides (ldhs) are a type of 2d anionic clay that is composed of layers (nazir et al., 2022) . ldh has a structure similar to brucite with a large surface area, where m(ii) is surrounded by six hydroxide ions, for instance, and forms an octahedral array that is connected to form an infinite 2d structure (ahmed and mohamed, 2022) . these adsorbents have excellent mg molecule adsorption performance, but for this purpose, sustainable, cost-effective adsorbents made from biomass are still required (wang et al., 2018) . also, when compared to several previously described adsorbents, biomass-based adsorbents appear to be more environmentally friendly, cost-effective, and sustainable (juleanti et al., 2021) . designing biomass-derived adsorbents to remove mg from aqueous media is therefore appealing. lignin, an https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.305-311&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.305-311 palapa et. al. science and technology indonesia, 8 (2023) 305-311 amorphous high-molecular aromatic polymer, is the second most prevalent biomass component on the planet after cellulose (zong et al., 2023) . the pulp and paper industry currently produces about 50 million tons of lignin as a byproduct each year. the vast majority of lignin that has been burned up to this point has been done so to create energy, which has resulted in significant lignin resource waste (du et al., 2023) . the use of inexpensive, readily available industrial waste lignin to produce effective functional materials for environmental remediation is a great solution when taking into account greater lignin usage and water remediation (wang et al., 2022) . a three-dimensional network structure and the abundance of functional groups that include oxygen in lignin give it more potential for functionalization (hamad et al., 2022) . in this work, the coprecipitation technique was used to prepare the lignin-zn/al. many cutting-edge characterization techniques were used to examine the physicochemical characteristics of lignin-zn/al. also, the potential of lignin-zn/al was examined, as well as its application to simulated textile wastewater. 2. experimental section 2.1 materials all chemicals were used without any further purification. sodium chloride, sodium hydroxide, aluminum nitrate nonahydrate, chloride acid, and zinc nitrate hexahydrate were purchased from sigma aldrich and merck. lignin and distilled water were purchased from tokyo chemical industry and brataco, respectively. 2.2 preparation lignin-zn/al and characterization lignin-zn/al was prepared by the coprecipitation method. both 0.25 m aluminum nitrate nonahydrate and 0.75 m zink nitrate hexahydrate were dissolved in 30 ml of distilled water, respectively. the solutions were added sodium hydroxide 2 m to ph 8 and stirred at 70°c for 4 h. afterward, the zn/al added 3 g lignin was under continuous stirring for 3 days, filtered, and dried. the characterization of lignin-znal using fourier transfer infra-red (ftir) (shimadzu), x-ray diffractometer (xrd) (rigaku), and surface area analyzer (quantachrome). 2.3 adsorption process of mg batch adsorption tests were conducted in a shaker. investigations were into the effects of temperature (30–60°c), initial dye concentration (60–100 mg/l), contact time (10–180 min), and phpzc (2–11). usually, 100 ml of beaker glass was filled with 30 ml of mg solution and 30 mg of lignin-zn/al. liquid aliquots were obtained after adsorption and centrifuged. then, the supernatant was examined using a uv-vis spectrophotometer set to the maximum wavelength of 617 nm. equation 1 was used to determine the concentration of mg. q = (c0-c)×v m (1) where q is adsorption capacity at t time (mg/g); c0 and c are initial concentration and concentration for t time of mg, respectively (mg/l); v is the volume of mg (l); m is the mass of lignin-zn/al (g). 3. results and discussion ft-ir spectra of zn/al, lignin, and lignin-zn/al were presented in figure 1. the ftir spectra of lignin-zn/al displayed at 3448, 2939, 1620, 1381, 1118, 1041, and 601 cm−1. the stretching vibration of -oh from zn/al is responsible for appearing of the broad bandwidth 3448 and 1620 cm−1 (ahmad et al., 2023b) . the band at 2939 cm−1 is stretching vibration of aliphatic -ch from lignin and the distinctive peak at bandwidth 1381 cm−1 is anion interlayer no3− from zn/al (zubair et al., 2022) . the peak at 1118 and 1041 cm−1 are ascribable to c-o and c-o-c from lignin, respectively (sun et al., 2022) . the metal oxide bond vibration is attributed to the band at 601 cm−1 (chen et al., 2022) . figure 1. fourier transfer infra-red results of adsorbents the usual zn/al xrd pattern can be seen in figure 2, where the characteristic peaks are located at 10.1° and 20.1°, respectively, and correspond to the basal spacings of d003 and d006, respectively (yuliasari et al., 2023) . the 101 and 110 planes are responsible for two further linked peaks at 29.4° and 60.4°, respectively. the xrd of the lignin is depicted in figure 2 and displays the distinctive peak of carbon material at 19.1° and 33.9° (sturgeon et al., 2014) . the xrd results of the lignin-zn/al mixture reveal the presence of distinctive zn/al and lignin reflections. when evaluating the lignin-zn/al structure, the specific surface area and pore size are important factors. table 3 quantitatively displays the lignin-zn/al, lignin, and zn/al pore’s structure (d), surface area (sbet ), and pore volume (vp). the © 2023 the authors. page 306 of 311 palapa et. al. science and technology indonesia, 8 (2023) 305-311 table 1. the surface area of adsorbents adsorbent sbet (m2/g) d (nm) vp (cm3/g) lignin-zn/al 7.125 1.960 0.007 lignin 4.079 2.255 0.009 zn/al 1.968 27.687 0.006 table 2. kinetic data of adsorbents pseudo-first-order pseudo-second-order adsorbent qeexp qecalc k1 r 2 qecalc k2 r 2 (mg/g) (mg/g) (min−1) (mg/g) (g/mg.min) lignin-zn/al 45.642 17.527 0.024 0.850 47.170 0.002 0.999 lignin 39.892 29.336 0.036 0.941 44.053 0.002 0.993 zn/al 36.148 39.455 0.037 0.995 39.683 0.002 0.996 figure 2. x-ray diffractometer results of adsorbents results show that lignin-zn/al has an average surface area of 7.125 m2/g and pore sizes of 1.9620 ≈ 2 nm. the surface area of zn/al increase after combining with lignin. our findings demonstrate the presence of mesopores in the lignin-zn/al structure, which have iupac-recommended diameter ranges of 2–50 nm (heo et al., 2022) . the n2 adsorption/desorption curves and bjh (barrett, joyner, halenda) pore size distributions of lignin-zn/al are shown in figure 2. the ligninzn/al nitrogen adsorption-desorption isotherm, as reported by iupac, showed a type-iv curve, indicating that it had a mesoporous structure. the h3 kind of hysteresis loop also provides evidence for the presence of mesopores within the lignin-zn/al complex. the phpzc of is the point when there is no charge at all. figure 3. nitrogen adsorption-desorption results of adsorbents when the ph of the solution is low, shaking causes h+ to migrate from the solution to the surface of the lignin-zn/al, lignin, and zn/al, raising the ph. when the solution has a high ph, h+ diffuses into the solution from the surface of ligninzn/al, lignin, and zn/al. this reduces the ph of the solution. h+ ions do not migrate at the point where the initial and final phs meet, indicating that phpzc is the point of convergence. lignin-zn/al, lignin, and zn/al had phpzc values of 6.09, 3.01, and 6.09, respectively, as illustrated in figure 4. ligninzn/al, lignin, and zn/al are positively charged when the ph of the solution is less than phpzc, and they are negatively charged when the ph of the solution is more than phpzc . table 2 lists the resulting parameters after the experimental © 2023 the authors. page 307 of 311 palapa et. al. science and technology indonesia, 8 (2023) 305-311 table 3. isotherm data of mg adsorption adsorbent t (°c) freundlich langmuir n kf r2 qmax kl r2 lignin-zn/al 30 5.230 1.431 0.828 78.125 0.233 0.994 40 5.959 1.452 0.781 79.365 0.341 0.995 50 7.930 1.490 0.645 83.333 0.723 0.996 60 1.101 1.506 0.668 84.034 1.469 0.999 lignin 30 1.978 1.228 0.878 67.568 0.076 0.955 40 2.033 1.244 0.882 71.942 0.075 0.917 50 2.439 1.291 0.928 72.464 0.093 0.985 60 2.475 1.309 0.947 78.740 0.102 0.981 zn/al 30 0.876 2.037 0.880 23.310 0.121 0.982 40 1.071 1.903 0.763 26.954 0.155 0.954 50 1.388 1.789 0.732 30.675 0.203 0.956 60 1.916 1.684 0.778 36.364 0.342 0.980 table 4. several adsorbents to the adsorption of mg adsorbent qmax (mg/g) references lignin-zn/al 84.034 this study lignin 78.740 this study zn/al 36.364 this study avena sativa 83 banerjee et al. (2016) pine cone 111.1 kavci (2021) graphene oxide aminated lignin aerogels 113.5 chen et al. (2020) halloysite nanotube 74.95 altun and ecevit (2022) active carbons 58 hijab et al. (2021) chitosan-zink oxide 11 muinde et al. (2020) pact@𝛾-fe2o3 62.89 hasan et al. (2020) figure 4. phpzc of lignin-zn/al, lignin, and zn/al figure 5. contact time between adsorbents and adsorbate © 2023 the authors. page 308 of 311 palapa et. al. science and technology indonesia, 8 (2023) 305-311 data are fitted to the kinetics models. the pseudo-second-order equation is the most appropriate one to describe the adsorption kinetics of lignin-zn/al, lignin, zn/al for mg, as shown by the analysis of correlation coefficients shown in table 2. all r2 of the pseudo-second-order models are much closer to 1.0 than pseudo-first-order models. this suggests that the process of adsorption involves chemisorption (rashed et al., 2022) . isotherm studies were carried out to comprehend the mg adsorption equilibrium distribution between the aqueous and the lignin-zn/al, lignin, and zn/al phases. due to their widesp read acceptance and popularity for precisely characterizing adsorption processes, the langmuir and freundlich models were used to explain the adsorption process in order to achieve that. the parameters obtained after fitting the isotherm research data obtained at various temperatures into these models are shown in table 3. the langmuir model best represented the mg adsorption onto all adsorbents, according to the r2 values for the three adsorbents. it follows that monolayer adsorption in nature meng et al. (2019) would be a more accurate way to characterize the mg solution’s adsorption onto lignin-zn/al, lignin, and zn/al. the lignin-zn/al, lignin, and zn/al were shown to have maximum langmuir adsorption capacities of 83.034, 78.740, and 36.364 mg/g, respectively. zn/al adsorption capacity increased 2.28 times after being composited with lignin. several adsorbents for the adsorption of mg are displayed in table 4. 4. conclusion preparation lignin-zn/al is successful by the coprecipitation method. the characterization by ftir, xrd, and bet shows the physicochemical characteristics of lignin-zn/al. the adsorption process showed better results after zn/al and lignin were combined. this can be seen from the increase in the adsorption capacity of zn/al lignin by 2.28 times. thus, ligninzn/al can be one of the adsorbents for the malachite green adsorption process. 5. acknowledgment the authors acknowledge to research center of inorganic materials and complexes, fmipa universitas sriwijaya for the support of this work. references ahmad, n., f. s. arsyad, i. royani, and a. lesbani (2023a). charcoal activated as template mg/al layered double hydroxide for selective adsorption of direct yellow on anionic dyes. results in chemistry, 5(1); 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443–450 yuliasari, n., a. wijaya, r. mohadi, and a. lesbani (2023). enhanced effectiveness on phenol removal by mgcr© 2023 the authors. page 310 of 311 palapa et. al. science and technology indonesia, 8 (2023) 305-311 ldh/microcrystalline cellulose composite and regeneration study with green desorption reagent. science and technology indonesia, 8(1); 151–159 zong, e., r. fan, h. hua, j. yang, s. jiang, j. dai, x. liu, and p. song (2023). a magnetically recyclable ligninbased bio-adsorbent for efficient removal of congo red from aqueous solution. international journal of biological macromolecules, 226; 443–453 zubair, m., h. a. aziz, i. ihsanullah, m. a. ahmad, and m. a. al harthi (2022). engineered biochar supported layered double hydroxide-cellulose nanocrystals composite-: synthesis, characterization and azo dye removal performance. chemosphere, 307; 136054 © 2023 the authors. page 311 of 311 introduction experimental section materials preparation lignin-zn/al and characterization adsorption process of mg results and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper improving the characteristics of edible film using modified cassava starch over ethanol precipitation nazarudin1,3*, ulyarti2,3, indra agung pratama2, suripto dwi yuwono4 1chemical engineering study program, university of jambi, mendalo, jambi, 36361, indonesia2technology of agricultural product, university of jambi, mendalo, jambi, 36361, indonesia3centre of excellence on bio-geo material and energy, university of jambi, mendalo, jambi, 36361, indonesia4chemistry department, university of lampung, gedung meneng, lampung, 35145, indonesia *corresponding author: nazarudin@unja.ac.id abstractcassava starch has been widely explored as film forming material, however its hydrophilicity restricts its application. hydrophobicmaterial such as modified starch can be used in the film elaboration to improve its quality. this study aims to examine the effect ofmodified cassava starch concentration on the physical, barrier, and mechanical properties of edible films. a completely randomizeddesign was used with 5 concentrations of modified starch at 0%, 5%, 10%, 15%, and 20% and 4 repetitions to obtain a total of20 experimental combinations. the anova showed that the modified starch concentration affected the compressive strength,thickness, transparency, and solubility of the edible film, but has no effect on its water vapor transmission rate (wvtr). usageof 20% modified starch gave the product with the best characteristics at 0.22 mm thickness, 89.45 n/m2 strength, 6.484%/mmtransparency, 52.19% solubility, and 21.00 g/m2.hour wvtr. keywordscassava starch, precipitation, modified starch, edible film received: 3 september 2022, accepted: 25 november 2022 https://doi.org/10.26554/sti.2023.8.1.32-37 1. introduction cassava (manihot utilissima) is one of the food crops with the highest production in indonesia, and its tubers contain starch as the main component. it also has a high amylose content, which allows it to be used as raw material for edible lms. the lms can be used for packaging to resist mass transfer or as a carrier for food additives. the use of cassava starch as a single main ingredientproduceslmswith lowbarrierandmechanical properties. to improve this weakness, researchers suggest a combination of several components to produce edible lms (zhouetal.,2021; pérez-vergaraetal.,2020; silvaetal.,2019; mantovan et al., 2018; ulyarti et al., 2022). some studies stated that the addition of modied starch with a dierent morphological shape or size can overcome these problems (ulyarti et al., 2022; wolf et al., 2018; roy et al., 2020; farrag et al., 2018; ulyarti et al., 2020). modied starch produced from an acid hydrolysis of starch is shown to decrease water vapor transmission rate and increase lm strength when incorporated to a lm (roy et al., 2020). this might be due to both a more hydrophobic nature of the modied starch and the fact that the incorporation of the modied starch with nano sized particles into lm produces a more compact lm (le corre and angellier-coussy, 2014). starch modication using alcohol precipitation, on the other hand, produces similar properties of modied starch as acid hydrolysis modication but gives higher yields. furthermore, alcoholic precipitation is more simple and cheaper than acid hydrolysis method. these are the reason for using modied starch from alcoholic precipitation for composite lm. precipitation method in starch modication involves the combination of physical and mechanical treatment of starch. the substrate is gelatinized in the presence or absence of surfactant and continues to undergo rapid stirringduring the addition of non-solvent reagents, which causes retrogradation (qin et al., 2016; saari et al., 2017). the ratio of a non-solvent ethanol reagent to starch solution inuences the morphology and the size of modied starch using the precipitation method (chin et al., 2011). a composite lm produced from native cassava starch and the modied form through the alcoholic precipitation method usingahot plate at 100°c showed abetterwatervapor transmission rate (wvtr) and strength (ulyarti et al., 2020). similar results have been reported for composite lm from corn and pea starch (farrag et al., 2018). therefore, this study aims to https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.32-37&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.32-37 nazarudin et. al. science and technology indonesia, 8 (2023) 32-37 examine the eect of modied cassava starch concentration on the physical, barrier, and mechanical properties of edible lm, as well as to determine the modied starch concentration that produces lm with the best characteristics. 2. experimental section 2.1 materials this study used cassava tuber aged 5-6 months, which was harvested at simpang rimbo jambi. the chemicals glycerol, absoluteethanol, calciumchloride, sodiumchloride, andmg(no3)2 were from merck. 2.2 cassava starch extraction the cassava tubers were peeled, washed, and grated. they were then mixed with water in a ratio of 1:2, and mashed using a blender. the cassava pulp was ltered using a 200-mesh sieve, and the ltering results were deposited for 4 hours. the supernatant was then discarded, while the precipitate formed at the bottom of the settling basin was washed with water and redeposited for 30 minutes. subsequently, the starch precipitate was separated from the supernatant, dried using a drying oven at 50°c for 18 hours, and sieved using a 60-mesh sieve. 2.3 preparation of modied cassava starch the preparation of modied starch followed the method described by chin et al. (2011). a total of 1 gram of starch was dissolved in 100 ml distilled water, and then heated at 100°c using a hot plate for 30 minutes with constant stirring. furthermore, the starch solution was added dropwise to a 500 ml of 96% ethanol with continuous stirring. the solution was left for 8 hours at room temperature with constant stirring and then centrifuged at 2,500 rpm for 15 minutes. the washing of the precipitate was carried out with absolute ethanol 3 times, followed by drying using cool-dry air in a refrigerator. the modied starch was then sieved with a 60 mesh sieve. 2.4 preparation of modied cassava starch composite film the preparation of composite lm followed the method described by ulyarti et al. (2020). the composite lms used modied starch at dierent concentrations, i.e., 0%, 5%, 10%, 15%, and 20% of the total starch. the composite lms were prepared using a mixture of starch and modied starch (4 g), water (143 g), and glycerol (3 g). the native cassava starch was stirred in distilled water using amagneticstirrertoformasuspension. itwas thenheatedusing a hot plate at 80°c with continuous stirring for 40 minutes, followed by the addition of modied starch. the solution was then homogenized using a vortex without heating. atotal of 25 gram lm solution was poured into a petri dish with a 9.2 cm diameter and then dried in an oven at 60°c for 24 hours. the edible lms were placed in a desiccator for 3 days, removed from the mold, and stored in adesiccatorcontainingasaturated solution of mg(no3)2 for 2 days before analysis. 2.5 starch granule morphology and edible film starch and edible lm were imaged using a scanning electron microscope (sem) (model jeol jsm 6510 la). before the analysis, the starch samples were dispersed with alcohol and coated with gold powder. images were then taken at 500x and 1000x magnication on the surface of the edible lm as well as its cross-section. 2.6 particle size distribution the size distribution of starch granules was determined using sem images of the starches and analyzed using image j. 2.7 water vapor transmission rate/wvtr calcium chloride was placed in a test tube and the mouth was sealed with the lm sample. the tube was then placed in a desiccator containing saturated sodium chloride salt solution at an rh of 75%. subsequently, it was weighed for 3.5 hours with an interval of 30 minutes. the increase in the mass of the tube was then plotted as a function of time. wvtr calculation was carried out using the formula below: wvtr = slope a (1) description: wvtr =water vapor transmission rate (g/m2/hour) slope =change in weight per unit time (g/hour) a =film area (m2) 2.8 compressive strength (ulyarti et al., 2020) instrumentation lfratexture analyzer brookeld brand was used to measure the compressive strength with a probe-type ta 7 60 mm. the cycle count test was then carried out with 2 g trigger, 2 mm distance, and 2 mm/s speed. the size of the edible lm sample to be tested was 5×2 cm. 2.9 film thickness the samples were measured using a micrometer at 5 dierent places. the thickness of the edible lm was expressed in terms of the average thickness. 2.10 transparency (piñeros-hernandez et al., 2017) the lm was cut into squares with a size of 50×10 mm and placed in a spectrophotometer cell. the %transmittance was measured using a uv-vis spectrophotometer at a wavelength of 600 nm. the transparency of the edible lm was then calculated with the formula below: transparency = log%t thickness (%/mm) (2) © 2023 the authors. page 33 of 38 nazarudin et. al. science and technology indonesia, 8 (2023) 32-37 2.11 solubility the lm sample was cut into sizes of 2×2 cm, placed in 50 ml of water, and then soaked for 24 hours with periodical stirring. the solution was ltered using a lterpaperof unknown weight. subsequently, the paper and residue were dried at 105◦c for 24 hours, and the amount of undissolved lm was weighed. the data obtained were then used to calculate the %solubility of the edible lm in water. 2.12 statistical analysis statistical analysis obtained from 4 replicates was done by anova. duncan’s new multiple range test at a 5% signicance level was applied to nd out signicant dierences in mean. 3. result and discussion 3.1 native and modied cassava starch the yield of modied cassava starch produced in this study was 83.55%. the granules of native cassava starch are round, elliptical to oval shape with asmooth surface as shown in figure 1a. meanwhile, the granule of the modied form experienced shrinkage and folding with a rough surface, as shown in figure 1b. during the modication process, gelatinization led to the dissolution of some starch components, which damaged the granule structure. starch granules are composed of two types of polysaccharide called amylose and amylopectin. these molecules form amorphous and crystalline lamellae in the granule (lecorre et al., 2011). the amorphous area is more susceptible to hydrolysis than the crystalline area. in yam starch, the granules exhibit semi-crystalline structure (nadia et al., 2014) in which the center of the granules is mainly composed of amorphous structure while the crystalline present in the outer layer (wang et al., 2008). during modication of starch in the present study, along with a strong destruction level in the center of granules, it can be seen that a lower destruction level of starch granules also occurred in the granule surface shown by the rough surface as seen in figure 1b. the distribution size of both native and the modied cassava starch in table 1 shows that the modication disintegrates the granules and disrupts the inter and intramolecular bonding within the granules leading to smaller sizes of particles. these small particles formed aggregates as seen in figure 1b. figure 1. native cassava starch granules (a) and modied cassava starch granules precipitation method (b) table 1. the distribution size of starch particles size (`m) native modied < 10 114 206 10 19.99 54 187 20 29.99 11 74 30 39.99 10 36 40 49.99 7 19 50 59.99 4 16 60 69.99 7 13 70 79.99 3 7 80 89.99 2 2 90 99.99 3 6 >100 45 38 total 260 604 3.2 edible film morphology the edible lm morphology can be observed using a scanning electron microscope (sem) on the surface and cross-section. sem analysis on the surface showed that the higher the concentration of modied starch added, the rougher the appearance, as illustrated in figure 2. the surface of the lm without modied starch (2a) was smoother and had very few visible solids compared to the other lms, which were slightly wavy (2b-e). these rough surfaces of the lms indicate that they were less homogeneous. the cross-section of the edible lms shows an increasing thickness of the lm. the lm without modied starch has a lot of small empty spaces. only little empty spaces are seen with increasing modied starch concentration but bigger. overall, the cross section of lm with increasing modied starch concentration has ner cross section indicating a slightly denser lm, as shown in figure 2a-e. 3.3 ftir spectra the ftir spectra of the 2 starch types showed that the modication process did not change the functional groups present in them (figure 3). however, there were dierences in the intensity of the hydroxyl group transmission and bond vibration withwater, at3,000–3,600cm−1 and1,600cm−1. thebroader modied starch peak at 3,000–3,600 cm−1 indicated an extension of hydrogen bond formation (orsuwan and sothornvit, 2017). as the intermolecular bonds in the amorphous area were broken, new bonds were formed between the modied granules and water available during modication through hydrogen bonding. the sharper peak at 1635 cm−1 on the modied starch spectrum represented a more bound water (ulyarti et al., 2022). the ftir spectra of edible lms with 0%, 5%, and 10% modied starch was similar to that of normal starch, except the signal loss at a wave number of 2,931 cm−1 which corresponds to stretching vibration of c–h (agi et al., 2019). concentrations above 10% produced lms with a weaker and missing functional group signal. © 2023 the authors. page 34 of 38 nazarudin et. al. science and technology indonesia, 8 (2023) 32-37 figure 2. sem image of surface and cross-section of edible film with various concentrations of modied starch at 500× magnication. film surface 0% (a), 5% (b), 10% (c), 15% (d), and 20% (e), film cross-section 0% (a), 5% (b), 10% (c), 15% (d), and 20% (e) figure 3. ftir spectra of starch (a) and edible film (b) where ns: native starch, ms: modied starch 3.4 the characteristics of the edible film with the addition of modied starch the addition of modied starch tends to decrease the wvtr of the edible lm, but its con-centration has no statistically signicant eect (p<5%), as shown in figure 4. the water vapor transmission rate is one of the most important parameters in assessing the quality of edible lms. wvtr is the velocity of water vapor passing through a unit area of lm during a certain unit of time. it is strongly inuenced by rh, aw, temperature, plasticizer concentration, edible lm-forming properties, and the type of material used. the results showed that wvtr of the edible lm starch decreased to 21.00 g/m2.hour after the addition of modied starch. this nding indicates that concentrations of ≤20% tend to inhibit wvtr. similar results were also obtained in previous studies where an increase in concentration led to a slight decrease in wvtr (farrag et al., 2018; ulyarti et al., 2020). the values obtained in this studyare lower than those reported for cassava starch based edible lms where an average of 32.6 g/m2.hour to 62.4 g/m2.hour was recorded after the addition of gelatin (ulyarti et al., 2020) and 25.36 to 30.35 g/m2.s for starch/chitosan and starch/gelatin lm (silva et al., 2019). although less homogeneous, the denser the crosssection of the lm with higher the concen-tration of modied starch is one reason for lower wvtr of the lm. furthermore, the ftir result conrms the changes on the microstructure of the starch lm upon modied starch presence at concentration higher than 10%. figure 4. wvtr edible film at several levels of modied starch concentration table 2 shows that the modied starch concentration had a signicant eect (p<5%) on the compressive strength, thickness, transparency and the solubility of the lms. compressive strength is a mechanical property of edible lm as well as a parameter that determines the ability to withstand loads. it also aects the ability of the material to with-stand pressure when applied at the maximum limit. table 1 shows that the addition of modied starch in the manufacture of edible lms signicantly increased the compressive value by strengthening its matrix (p<5%). the value obtained also aects the ability of the lm to protect the product. high compressive strength is © 2023 the authors. page 35 of 38 nazarudin et. al. science and technology indonesia, 8 (2023) 32-37 table 2. the characteristics of the edible film with the addition of modied starch modied starch concentration (%) compressive strength (n/m2) thickness (mm) transparency (%) solubility (%) 0 56.18a±0.15 0.18a±0.002 9.922d±0.51 75.10e±1.28 5 66.30b±0.11 0.19b±0.001 9.419c±0.44 69.72d±1.90 10 73.46c±0.29 0.20c±0.001 9.286c±0.20 63.16c±2.32 15 80.05d±0.52 0.21d±0.005 8.776b±0.22 57.43b±4.80 20 89.45e±0.15 0.22e±0.003 6.484a±0.14 52.19a±3.62 description: the numbers followed by the same lowercase letters in the same column are not signicantly dierent according to the dnmrt test at the 5% level needed for food product packaging to protect them during the handling, transportation, and marketing processes. the compressive strength value recorded for cassava starch edible lm in this study is higher compared to another study with 27.66 n/m2 to 37.60 n/m2 for cassava starch edible lm withadditionofgelatin (ulyarti etal.,2020). thedevelopment of dense lm structure as seen in sem images (huntrakul et al., 2020; piñeros-hernandez et al., 2017), less hydrogen bond formation and less bound water in lm as indicated by ftir (ulyarti et al., 2022; orsuwan and sothornvit, 2017) may explain this. thickness is a physical property of edible lm, which is inuenced by the concentration of dissolved solids in the lm solution as well as the weight of the lm solution per unit area of the mold used. film thickness is an important parameter that aects its application as a material for product packaging. it also aects other parameters, such as transparency, tensile strength, and the transparency rate of steam or gas on the material (gonzález et al., 2015; gujral et al., 2021; hakke et al., 2022; totosaus et al., 2020). the results showed that increasing the concentration of modied cassava starch signicantly increased the thickness of the edible lm (p<5%), as shown in table2. thesimilarresultwasreportedforpotatostarch-based nanocomposite lm (gujral et al., 2021). transparency of the edible lm, if applied for food packaging, directly inuences the consumer’s acceptance. the transparency was measured by the amount of light it can transmit. the values obtained in this study are presented in table 1. the analysis of variance showed that the modied starch concentration had a signicant eect (p<5%) on the transparency of the lm, and it decreased with increasing modied starch concentration. this result is in line with that of a previous studywhere there was also a decrease in the transparency of composite edible lms produced from zein (corn protein) nanoparticles and corn starch (zhang and zhao, 2017). the addition of materials, such as modied starch increases the total dissolved solids, which together with the compactness and homogeneity, greatly aects the level of transparency (alves et al., 2015). in this study, the amount of total dissolved solid was kept constant, but there is an increase in the percentage of modied starch leading to a less homogeneity lm as seen in sem images of lm surface and so the transparency. the solubility of edible lms is one of the important factors used in determining lm quality. it is also used to determine their designation, for example, sausage products require lms with high solubility and low transmission rates, which makes them easy to consume and not easily oxidized. the values of lm solubility obtained in this study are presented in table 1. the variance analysis showed that the addition of modied starch had a signicant eect (p<5%) on the solubility of the edible lm. there was a decrease in the solubility with increasing modied starch. this result is in line with the decreasing in wvtr and the missing in functional groups detected by ftir for hydrogen bonding and bound water. similar results had been reported that decreasing of both wvtr and solubility occur simultaneously (pérez-vergara et al., 2020). 4. conclusion the concentration of modied starch has a signicant eect on the compressive strength, thickness, transparency, and solubility of edible lms. although statistically insignicant, the increase in modied starch concentration tends to decrease wvtr of the lm. the best lm produced with 20% modied cassava starch, containing 3.2 g native starch, 0.8 g modied starch, 3 g glycerol, and 143 g distilled water, has 21.00 g/m2.hour wvtr, 89.45 n/m2 compressive strength, 0.22 mm thickness, 6.484%/mm transparency, and 52.19% solubility. 5. acknowledgment the authors are grateful to the faculty of agriculture, university of jambi for the research grant through the 2021 pnbp scheme and center of excellent on bio-geo material and energyuniversityof jambi for facilitating the research equipment used in the research. references agi, a., r. junin, a. gbadamosi, a. abbas, n. 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1230–1238 ulyarti, u., n. nazarudin, r. ramadon, and p. lumbanraja (2020). cassava starch edible film with addition of gelatin or modied cassava starch. in iop conference series: earth andenvironmentalscience, volume 515. ioppublishing, page 012030 wang, s., j. yu, j. yu, and h. liu (2008). granule structure of c-type chinese yam (dioscorea opposita thunb var. zhongbowen) starch by acid hydrolysis. food hydrocolloids, 22(4); 538–542 wolf, c., h. angellier-coussy, n. gontard, f. doghieri, and v. guillard (2018). how the shape of fillers aects the barrier properties of polymer/non-porous particles nanocomposites: a review. journal of membrane science, 556; 393– 418 zhang, s. and h. zhao (2017). preparation and properties of zein–rutin composite nanoparticle/corn starch films. carbohydrate polymers, 169; 385–392 zhou, y., x. wu, j. chen, and j. he (2021). eects of cinnamon essential oil on the physical, mechanical, structural © 2023 the authors. page 37 of 38 nazarudin et. al. science and technology indonesia, 8 (2023) 32-37 and thermal properties of cassava starch-based edible films. international journal of biological macromolecules, 184; 574–583 © 2023 the authors. page 38 of 38 introduction experimental section materials cassava starch extraction preparation of modified cassava starch preparation of modified cassava starch composite film starch granule morphology and edible film particle size distribution water vapor transmission rate/wvtr compressive strength 9 film thickness transparency 20 solubility statistical analysis result and discussion native and modified cassava starch edible film morphology ftir spectra the characteristics of the edible film with the addition of modified starch conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper development and validation of fast and simple fourier transform infrared spectrophotometric method for analysis of thiamphenicol in capsule dosage form nerdy nerdy1*, linda margata 1, nilsya febrika zebua 1, puji lestari 2, tedy kurniawan bakri 3, faisal yusuf 4, vonna aulianshah5 1faculty of pharmacy, universitas tjut nyak dhien, medan, 20123, indonesia2faculty of pharmacy, institut kesehatan deli husada deli tua, deli serdang, 20355, indonesia3faculty of mathematics and natural sciences, universitas syiah kuala, banda aceh, 23111, indonesia4faculty of pharmacy, sekolah tinggi ilmu kesehatan arjuna, toba samosir, 22384, indonesia5faculty of pharmacy, politeknik kesehatan kemenkes aceh, aceh besar, 23352, indonesia *corresponding author: nerdy190690@gmail.com abstractthe development of a method for identification and determination of thiamphenicol by fourier transform infrared will provideconvenience to developers because it is fast and easy for analysis. the research was carried out by utilizing the solubility ofthiamphenicol in methanol with three stages, namely method development, sample analysis, and method validation. the methoddevelopment stage showed that the specific peak of thiamphenicol was at a peak with a wavenumber of 1694.1 cm−1; this specificpeak of thiamphenicol was used for qualitative analysis and quantitative analysis of thiamphenicol in the capsule dosage form.the sample analysis showed that all analyzed thiamphenicol in capsule dosage form showed good results both qualitatively andquantitatively. qualitatively all the samples analyzed showed a specific peak at specific positions and specific wavenumbers. theseresults meet the requirements for containing thiamphenicol in the dosage form. quantitatively all the samples analyzed rangedfrom 97.97% to 102.24% by peak height and peak area. these results meet the requirements for active substance levels in generalpreparations within 90.0% to 110.0%. the method validation for peak height and peak area showed that the accuracy parameterhad a recovery percentage of 100.28% and 100.41% (between 98.0% to 102.0%), the precision parameter with a relative standarddeviation of 0.31% and 0.37% (not more than 2.0%), and the linearity parameter with a correlation coefficient of 0.9999 and 0.9997(not less than 0.99). the limit of detection value was 0.2971 mg/ml and 0.5338 mg/ml, the limit of quantitation value was 0.9004mg/ml and 1.6176 mg/ml, the range for both was 80% to 120%, and the specificity for both met the requirement. the fouriertransform infrared method has been successfully developed, applied, and validated for qualitative analysis and quantitative analysisof thiamphenicol in capsule dosage form. keywordsdevelopment, validation, fourier transform infrared, thiamphenicol, capsule received: 17 february 2023, accepted: 3 may 2023 https://doi.org/10.26554/sti.2023.8.3.344-352 1. introduction drugs have an important role in improving the quality of human life. a pharmaceutical dosage form should be tested for its quality, efficacy, and safety (zuccari et al., 2022) . in order to guarantee the quality, efficacy, and safety of a drug dosage form that has been distributed a stability study as well as a series of evaluation tests must be performed to fulfill the requirements (gupta et al., 2020) . the qualitative analysis for identification and the quantitative analysis for assay of active substances in the drug dosage form is one of the chemical evaluations that must be performed. it is a requirement that must be met to ensure the quality of a drug (chen et al., 2018) . thiamphenicol is a broad-spectrum antibiotic that can be used to treat infections caused by various gram-positive bacteria and gram-negative bacteria (laconi et al., 2022) . thiamphenicol works by inhibiting the growth of bacteria (bacteriostatic) while killing the bacteria (bactericidal) which may cause infection. thiamphenicol treats various bacterial infections, such as digestive tract infections, respiratory tract infections, and urinary tract infections (barbieri et al., 2022) . the thiamphenicol monograph in the dosage form is not listed in the compendial monograph (united states pharmacopoeia, indonesian pharmacopoeia, european pharmacopoeia, japanese pharmacopoeia or chinese pharmacopoeia). so there is no detailed information on a drug’s physical and chemical https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.344-352&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.344-352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 properties, pharmacological effects, dosage forms, and analysis methods; therefore it is necessary to find and develop analytical methods for qualitative analysis and quantitative analysis of thiamphenicol. various methods of analysis of thiamphenicol in dosage form have been developed, including ultraviolet spectrophotometric (martins and de oliveira, 2019) and high-performance liquid chromatography (patyra and kwiatek, 2019; wu et al., 2021; ye et al., 2022). high-performance liquid chromatography in drug analysis is the most reliable method in drug analysis (gupta et al., 2022) . the thiamphenicol residues was analyzed in medicated feeding stuffs by a liquid chromatography with diode array detector, equipped with phenyl column, water and acetonitrile were used as the mobile phase with the gradient elution program, ultraviolet detection at 223 nm (patyra and kwiatek, 2019) . the thiamphenicol and it metabolites in pork, beef, lamb, chicken, and their products have been determined by combination of solid-phase extraction with ultrahigh-performance liquid chromatography-tandem mass spectrometry, water and acetonitrile (gradient) as the mobile phase, and octadecyl silane column as the stationary phase (wu et al., 2021) . the thiamphenicol residues was analyzed in aquatic products by a liquid chromatography with tandem mass spectrometry detector, equipped with pentafluorophenyl propyl column as stationary phase, ammonium acetate solution and methanol as the mobile phase with the gradient elution program (ye et al., 2022) . the disadvantage of the high-performance liquid chromatography method is that it requires special analysts to prepare and operate because preparations and operations require special competency skills (pitigoi, 2022) . the materials used in hplc are also expensive, such as reagents (which need a lot of organic solvents), spare parts, and columns (timchenko, 2021) . drug analysis by ultraviolet spectrophotometry is a fairly good and fast method (patel et al., 2022) . analysis of thiamphenicol in soft capsule dosage form shows that ultraviolet spectrophotometry can analyze thiamphenicol properly without being affected by additional ingredients in the dosage form and has good validity (martins and de oliveira, 2019) . the main disadvantage of the ultraviolet spectrophotometric method is its low level of selectivity due to interference from other components in the sample (hladová et al., 2019) . this overlapping effect increases the response value of the component to be analyzed due to the presence of other components (ríos reina and azcarate, 2022) . another disadvantage of using this uv-vis spectrophotometer instrument is that the compound to be analyzed must have a chromophore group and a wavelength in the ultraviolet or visible region (kurzyna szklarek et al., 2022) . infrared is a spectrophotometric method and vibrational spectroscopy fadlelmoula et al. (2022) with many advantages such as being selective, easy, fast, simple, environmentally friendly, and nondestructive (estupiñán méndez and allscher, 2022) . infrared spectroscopy is a popular technique for analyzing various sample matrixes, namely pharmaceutical products (siregar et al., 2018; burela and mandalemula, 2023), food (sahachairungrueng et al., 2022; mendes and duarte, 2021), biological liquids (kamnev et al., 2021) , or environmental samples (tkachenko and niedzielski, 2022) . infrared spectrophotometry analysis can determine the functional groups in the compound (enders et al., 2021) and predict the chemical reaction (zeaiter et al., 2022) . this analysis is based on studying a characteristic peak from a certain functional group at a certain wavenumber or wavelength of a sample. fourier transform infrared is a powerful analytical method for qualitative analysis (identification) and quantitative analysis (assay) of several pharmaceuticals (gosar et al., 2022) . the validated method is needed to determine the active substance content of a drug dosage form with a modified analytical method or developed analytical method (susilo et al., 2022) . a new analytical method can be used if the conditions are adjusted to the laboratory condition and validation has been carried out (verch et al., 2022) . based on the description of the need and urgency of the research, this study is aimed at developing, applying, and validating a novel fourier transform infrared spectrophotometric method for qualitative analysis (identification) and quantitative analysis (assay) of thiamphenicol in capsule dosage form. 2. experimental section the descriptive research developed simple and fast analytical methods using fourier transform infrared spectrophotometric to determine the thiamphenicol level in capsule dosage form. the developed method was validated to ensure the procedure was suitable for its intended use. sampling was carried out purposively, and samples were taken without comparing one place with another because samples from various collection places were considered homogeneous (vasileiou et al., 2018) . 2.1 materials and tools the materials used included a methanol type pro analysis (merck), thiamphenicol (sigma aldrich), thiamphenicol capsule (phapros), thiamphenicol capsule (bernofarm), thiamphe nicol capsule (pyridam farma), thiamphenicol capsule (sanbe farma), thiamex® capsule (novapharin), thiamycin® capsule (interbat), nikolam® capsule (meprofarm), zicafen® capsule (graha farma), thianicol® capsule (dankos farma), and thislacol® capsule (metiska farma). the tools used included a fourier transform infrared type cary 630 (agilent), microlab type quant (agilent), and microlab type lite (agilent), analytical balance type entris 224-1s (sartorius), electronic multi dispenser pipettes type multipette e3x (eppendorf), ultrasonic cleaner type elmasonic srh 4/200 (elma), and other laboratory glassware. 2.2 method development the procedure used in the method development was modified from previous studies, and consisted of stages stock solution preparation and stages standard solution preparation (robaina et al., 2013) . © 2023 the authors. page 345 of 352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 2.3 stock solution to prepare a stock solution of thiamphenicol with a 100 mg/ml concentration, 5 g of the substance was placed in a 50 ml volumetric flask. then, 25 ml of methanol was added to the flask, and the mixture was sonicated for 15 minutes until it dissolved completely. methanol was added to the marked line, and the mixture was shaken well until it became homogeneous. 2.4 standard solution to prepare a standard solution of thiamphenicol with a 50 mg/ml concentration, 5 ml of the stock solution was transferred to a 10 ml volumetric flask. then, methanol was added to the marked line, and the mixture was shaken until it became homogeneous. the specific peak of thiamphenicol was then analyzed by measuring the blank (methanol) and the standard solution separately with a slit distance of 100 `m at wavenumbers ranging from 4000 cm−1 to 650 cm−1. the position and wavenumber of the specific peak were determined by overlaying the spectra of the blank and standard solution. this information was used for qualitative analysis. 2.5 sample analysis the procedure used in the sample analysis was modified from previous studies which consisted of stages series solutions preparation, stages sample solutions preparation, stages analysis for series solutions and stages analysis for sample solutions (robaina et al., 2013) . 2.6 series solutions preparation to prepare a series of thiamphenicol solutions with varying concentrations, volumes of 0.0, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0 ml of the stock solution were transferred to separate 10 ml volumetric flasks. then, methanol was added to the marked line, and the mixtures were shaken until they became homogeneous. this resulted in a series of thiamphenicol solutions with 0, 30, 35, 40, 45, 50, 55, 60, 65, and 70 mg/ml concentrations. 2.7 sample solutions preparation to prepare a sample solution of thiamphenicol, 20 capsules were ground and homogenized. the resulting powder was weighed to obtain a quantity equivalent to 500 mg of thiamphenicol. the powder was placed in a 10 ml volumetric flask, and 5 ml of methanol was added. the mixture was sonicated for 15 minutes until the powder dissolved completely. then, methanol was added to the marked line, and the solution was shaken until it became homogeneous. the solution was filtered using filter paper, and the first 1 ml of the filtrate was discarded. the remaining filtrate was collected to obtain a theoretical sample solution of thiamphenicol with a 50 mg/ml concentration. 2.8 analysis of series solutions series solutions were executed the measurements with slit distance 100 `m for series solution separately at wavenumbers 4000 cm−1 to 650 cm−1, analyzed the baseline, peak height, and peak area of the specific peak (position and wavenumber) of thiamphenicol by overlay of the series solutions. the baseline, peak height, and peak area of the specific peak (position and wavenumber) of thiamphenicol was further used for quantitative analysis (each concentration was replicated six times). the study continued with plotting the calibration curve, calculating the regression equation and calculating the determination coefficient. the regression equation was used additionally to calculate the thiamphenicol concentration in the test solution. the determination coefficient was used further to analyze the degree of determination of peak height and peak area to the thiamphenicol concentration. 2.9 analysis of sample solutions sample solutions were executed the measurements with a slit distance of 100 `m for sample solutions separately at wavenumbers 4000 cm−1 to 650 cm−1. the peak height and peak area of the specific peak (position and wavenumber) of thiamphenicol was then analyzed for further calculating the thiamphenicol concentration from sample solutions (each sample was replicated six times). the study continued by calculating the thiamphenicol level by comparing the actual thiamphenicol concentration to the theoretical thiamphenicol concentration, then the average was calculated, statistical analysis was performed, and the standard deviation was calculated. 2.10 method validation the procedures used in the method validation have been modified from previous studies which consisted of accuracy, precision, linearity, limit of detection, limit of quantitation, range, and specificity (wadher and supekar, 2019) . 2.11 accuracy and precision the accuracy parameter was assessed using the standard addition method to validate the method. the recovery percentage was measured in three different ranges: 80%, 100%, and 120%, where each range consisted of 70% of the analyte and 30% of the active pharmaceutical ingredient (standard). the analyte was measured both with and without the addition of a standard in each range, and the difference between the two results was compared with the actual levels to determine the percentage recovery. this process was repeated six times for each range, and the average was calculated along with the standard deviation. for the precision parameter, the relative standard deviation value was calculated from several recovery percentages obtained from the accuracy parameter. 2.12 linearity the linearity parameter for the method validation test was calculated by calculating the correlation coefficient of the peak height against the concentration or peak area against the concentration; the peak height or peak area of the various concentration of thiamphenicol concentration obtained from the measurement of series solutions of thiamphenicol concentration with six times replication for each concentration. © 2023 the authors. page 346 of 352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 2.13 limit of detection and limit of quantitation the limit of detection value and the limit of quantitation value were both calculated by calculating the peak height or peak area of the various concentrations of thiamphenicol concentrations obtained from the measurement of a series of solutions of different thiamphenicol concentrations with six times replication for each concentration. 2.14 range and specificity the range parameter for the method validation and the specificity parameter for the method validation were analyzed from the entire method validation parameter, and the complete sample analysis was obtained. 3. results and discussion 3.1 method development the study began with measurements taken separately at wave numbers 4000 cm−1 to 650 cm−1 against methanol as a blank and thiamphenicol solutions in methanol (thiamphenicol solution with a concentration of 50 mg/ml) as a standard solution. each spectrum obtained was analyzed for thiamphenicol’s specific peak (position and wavenumber) by overlaying the blank spectra and standard solution spectra. figure 1 shows the blank spectra (methanol) (x) and standard solution spectra (thiamphenicol in methanol) (y) at wavenumbers 4000 cm−1 to 650 cm−1. figure 2 shows the overlay blank spectra (methanol) indicated by a red line (-) and standard solution spectra (thiamphenicol in methanol) indicated by a blue line (-) at full scale wavenumbers 4000 cm−1 to 650 cm−1 and zoom wavenumbers 1800 cm−1 to 1100 cm−1. figure 1. blank spectra (methanol) (x) and standard solution spectra (thiamphenicol in methanol) (y) at wavenumbers 4000 cm−1 to 650 cm−1 figure 2. overlay blank spectra (methanol) indicated by a red line (-) and standard solution spectra (thiamphenicol in methanol) indicated by a blue line (-) at full scale wavenumbers 4000 cm−1 to 650 cm−1 and zoom wavenumbers 1800 cm−1 to 1100 cm−1 the specific peak of thiamphenicol is seen in the peak that appears in the standard solution spectra but does not appear in the blank spectra. in spectrophotometric analysis, the specific peak of the compound being analyzed is the peak that appears in the standard solution spectra but the peak does not appear in the blank spectra (akbel et al., 2022) . the overlapping analysis results show that most of the methanol absorption bands overlap with the thiamphenicol in methanol absorption bands except for the wavenumbers 1694.1 cm−1, 1313.9 cm−1, and 1151.7 cm−1. the drug wavenumber at the specific peak of thiamphenicol is in accordance with the literature; the three main peaks (high peaks absorbance) of thiamphenicol is at wavenumbers around 1690 cm−1, 1300 cm−1, and 1140 cm−1 (spectrabase, 2023) . in this study, qualitative analysis and quantitative analysis of thiamphenicol were performed on the specific peaks of thiamphenicol at wavenumber 1694.1 cm−1 because it had the greatest response (peak height and peak area). the peak with the greatest response will have the greatest sensitivity (gardegaront et al., 2018) , thus the wavenumbers used for qualitative analysis and quantitative analysis of thiamphenicol will be specific for thiamphenicol. the wavenumber 1694.1 cm−1 represents the carbonyl group which is more specific for the amide group. these results are consistent with the thiamphenicol structure and in accordance with the literature, which states that the wavenumber for the carbonyl group is in the range of wavenumber between 1850 cm−1 to 1650 cm−1 and, more specifically for the amide group is at a wavenumber lower than 1700 cm−1 (nandiyanto et al., 2019) . the peak position in © 2023 the authors. page 347 of 352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 wavenumber 1694.1 cm−1, which shows the difference between a solvent as a blank and solution of the compound being analyzed in a solvent as a standard solution, is the specific peak of the compound being examined and can be further used for qualitative analysis and quantitative analysis (liao et al., 2022) . after it is determined that the specific peak of thiamphenicol is at the peak position with wavenumber 1694.1 cm−1, then it can be further used for qualitative analysis. specific peaks in the spectrophotometric method that appear at certain wavenumbers or at a certain wavelength are good markers and are used for the qualitative analysis of compounds analyzed in mixtures (mabasa et al., 2021) . the quantitative analysis of thiamphenicol using fourier transform infrared was also carried out at the peak position with wavenumber 1694.1 cm−1 using the quantitative measurement method in the form of peak height or peak area. the quantitative analysis of the spectrophotometric method can be carried out with good results and with quantitative measurements of peak height or peak area (chrisikou et al., 2020) . 3.2 sample analysis the study was continued with measurements of series solutions (thiamphenicol solution with concentrations 0, 30, 35, 40, 45, 50, 55, 60, 65, and 70 mg/ml). the results were used to analyze the baseline, peak height, and peak area of the specific peak (position and wavenumber) of thiamphenicol for quantitative analysis. figure 3 shows the overlay spectra of series solutions (thiamphenicol in methanol with various concentrations) at full scale wavenumbers 4000 cm−1 to 650 cm−1 and zoom wavenumbers 1800 cm−1 to 1600 cm−1. the obtained baseline is in the range of 1733.21 cm−1 to 1638.16 cm−1, with a maximum position of 1694.08 cm−1; peak height and peak area from the series solutions measurement results were further calculated to find the determination coefficient and regression equation. the determination coefficient was 0.9998 for peak height with the regression equation y = 0.013005 × x + 0.078751, and the determination coefficient was 0.9994 for peak area with the regression equation y = 0.404536 × x + 8.677541. the determination coefficient obtained was not less than 0.99, which meets the requirements for a good coefficient of determination (sonawane et al., 2019) . a well-defined determination coefficient indicates that the peak height and peak area can be used for concentration determination using the regression equation (asthana et al., 2019) . the study revealed that for peak height and peak area, the intercept values were 0.078751 and 8.677541, while the slope values were 0.013005 and 0.404536. the intercept values obtained were higher than the slope values in the regression equation for both peak height and peak area. however, the relative magnitudes of intercept and slope do not necessarily indicate any issue with the model. in a linear regression equation, the intercept denotes the dependent variable’s value when the independent variable(s) is equal to zero. at the same time, the slope indicates the change in the dependent variable for a one-unit increase in the independent variable. therefore, the figure 3. overlay spectra of series solutions (thiamphenicol in methanol with various concentrations) at full scale wavenumbers 4000 cm−1 to 650 cm−1 and zoom wavenumbers 1800 cm−1 to 1600 cm−1 intercept and slope have different units of measurement and do not necessarily have a direct relationship (chen and chen, 2022) . the quantitative analysis of the spectrophotometric method by peak height and peak area has a response that is proportional to the concentration; a greater concentration will give a greater peak height and peak area (sadat and joye, 2020) . the developed method was applied for qualitative analysis and quantitative analysis of thiamphenicol in the capsule dosage form. the samples analyzed were thiamphenicol capsule dosage forms consisting of four generic names and six trade names. table 1 shows the sample analysis results for qualitative analysis and quantitative analysis of the thiamphenicol capsule dosage form based on peak height and peak area. the results showed that the thiamphenicol capsule dosage form contains thiamphenicol as the active pharmaceutical ingredient with a specific peak of thiamphenicol that appears at a specific position, namely at a wavenumber of around 1694.08 cm−1. qualitative analysis of the pharmaceutical dosage form is very important as an initial screening of pharmaceutical preparations before carrying out quantitative analysis to ensure quality, safety, and efficacy (li et al., 2019; srebro et al., 2022). the quantitative analysis of the thiamphenicol capsule dosage form shows thiamphenicol levels are in the range of 97.97% to 102.06% for the determination by using the peak height and the range of 98.08% to 102.24% for the determination by using the peak area. the level requirements for thiamphenicol in the thiamphenicol capsule dosage form are not listed in the compendial monograph, but the general requirement of a phar© 2023 the authors. page 348 of 352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 table 1. sample analysis results for qualitative analysis and quantitative analysis of the thiamphenicol capsule dosage form based on peak height and peak area sample qualitative results quantitative results peak height results peak area results thiamphenicol capsule (phapros) pass 100.01% ± 0.22% 100.09% ± 0.24% thiamphenicol capsule (bernofarm) pass 98.18% ± 0.42% 98.29% ± 0.36% thiamphenicol capsule (pyridam farma) pass 102.06% ± 0.45% 102.20% ± 0.34% thiamphenicol capsule (sanbe farma) pass 102.01% ± 0.30% 102.13% ± 0.24% thiamex® capsule (novapharin) pass 102.06% ± 0.40% 102.24% ± 0.28% thiamycin® capsule (interbat) pass 97.97% ± 0.43% 98.08% ± 0.34% nikolam® capsule (meprofarm) pass 100.96% ± 0.43% 101.07% ± 0.37% zicafen® capsule (graha farma) pass 100.39% ± 0.33% 100.42% ± 0.27% thianicol® capsule (dankos farma) pass 101.00% ± 0.31% 101.11% ± 0.27% thislacol® capsule (metiska farma) pass 99.01% ± 0.45% 99.11% ± 0.40% maceutical dosage form for the assay cannot be less than 90.0% and no more than 110.0% of the amount stated on the label (canada, 2018) . 3.3 method validation from the results, it can be seen that all of the thiamphenicol capsule dosage forms met the general requirements for the assay. the spectrophotometric fourier transform infrared has been successfully developed and has been successfully applied for qualitative analysis and quantitative analysis of thiamphenicol from thiamphenicol capsule dosage form, followed by the stages of validation of the analytical method. analytical method validation is an effort to prove through laboratory experiments a series of parameters to ensure that the analytical method that has been developed or modified is suitable for its purpose (shrivastava et al., 2018) . table 2 shows the method validation results for thiamphenicol analysis based on peak height and peak area. validation of the analytical method was carried out on a series of parameters. the accuracy parameter obtained a recovery percentage value of 100.28% for peak height and 100.41% for peak area. the recovery percentage value obtained met the requirements for accuracy parameters, which is between 98.0% to 102.0% (sudarman and haris, 2023) . the precision parameter obtained a relative standard deviation value of 0.31% for peak height and 0.37% for peak area. the relative standard deviation value obtained met the requirement for the precision parameter, which is not more than 2.0% (bui et al., 2021) . the linearity parameter obtained a correlation coefficient value of 0.9999 for peak height and 0.9997 for peak area. the correlation coefficient value obtained met the requirements for the linearity parameter, which is not less than 0.99 (matraszek żuchowska et al., 2022) . specifically, the limit of detection values was 0.9396 mg/ml and 1.6880 mg/ml for peak height and peak area, respectively. these values were approximately 30-54 times lower than the 50 mg/ml target concentration. on the other hand, the limit of quantitation values was 2.8472 mg/ml and 5.1153 mg/ml for peak height and peak area, respectively. these values were around 10-18 times lower than the 50 mg/ml target concentration. the method was found to have a high sensitivity, as evidenced by the very low limit of detection and limit of quantitation values obtained namegabe et al. (2022) this suggests that the fourier transform infrared method used in the study had a high sensitivity. the results of the analytical method validation for the range parameter obtained a value ranging from 80% to 120%. the parameter range is the lowest concentration limit and highest concentration limit, which has good accuracy, precision, and linearity, as well as proposed based on the intended use, which is determining drug levels in finished products that are 80% to 120% (lavanya et al., 2020) . regarding the specificity parameter, the results obtained are stated as passed, and these results are inferred from various validation parameters (accuracy, precision, linearity, limit of detection, limit of quantitation, and range). the specificity parameter of an analytical method is the ability to specifically measure the analyte in the presence of other components that might be expected to be present in the sample medium, thus producing a response for only a single analyte. in the assay, the specificity parameter was used to provide accurate and precise results on the levels or potency of the analyte in the sample (chavan and desai, 2022) . the thiamphenicol analysis in drug dosage form by ultraviolet spectrophotometry shows recovery percentage 99.91%, relative standard deviation 0.65%, correlation coefficient 0.9975, limit of detection 0.59 `g/ml and limit of quantitation 1.99 `g/ml (martins and de oliveira, 2019) . the thiamphenicol analysis by high-performance liquid chromatography shows recovery percentage > 95%, relative standard deviation value < 10%, determination coefficient > 0.99, limit of detection value 0.01 `g/kg, limit of quantitation value 0.02 `g/kg (ye et al., 2022) . the validation results of the analytical method of the fourier transform infrared method that has been developed in this study are compared to the ultraviolet spectrophotometry method and high-performance liquid-chromatography © 2023 the authors. page 349 of 352 nerdy et. al. science and technology indonesia, 8 (2023) 344-352 table 2. method validation results for thiamphenicol analysis based on peak height and peak area parameter validation results peak height peak area average specific range 80% 100.64% ± 0.22% 100.84% ± 0.17% recovery specific range 100% 99.99% ± 0.27% 100.01% ± 0.23% percentage specific range 120% 100.21% ± 0.26% 100.38% ± 0.20% accuracy (recovery percentage) 100.28% 100.41% precision (relative standard deviation) 0.31% 0.37% linearity (correlation coefficient) 0.9999 0.9997 limit of detection (mg/ml) 0.9396 1.6880 limit of quantitation (mg/ml) 2.8472 5.1153 range 80% to 120% 80% to 120% specificity passed passed method that previous researchers have reported. the results of the comparison show that the fourier transform infrared method has equivalent accuracy, precision, and linearity compared to the ultraviolet spectrophotometry method and the high-performance liquid-chromatography method. 4. conclusion the fourier transform infrared method has been successfully developed for thiamphenicol analysis. the specific peak of thiamphenicol was obtained at a peak maximum of 1694.08 cm−1 with a baseline between 1733.21 cm−1 to 1638.16 cm−1. the developed method has also been successfully applied for qualitative analysis and quantitative analysis of thiamphenicol in the capsule dosage form, ranging from 97.97% to 102.24%. all the thiamphenicol in the capsule dosage form with a generic name and trade name met the general requirements of a pharmaceutical dosage form for the assay, namely not less than 90.0% and not more than 110.0% of the amount stated on the label. the fourier transform infrared method has been successfully validated for thiamphenicol analysis. respectively for peak height and peak area, the accuracy parameter resulted in a recovery percentage of 100.28% and 100.41%, the precision parameter resulted in a relative standard deviation of 0.31% and 0.37%, and the linearity parameter resulted in a correlation coefficient of 0.9999 and 0.9997. respectively for peak height and peak area, the limit of detection value obtained was 0.2971 mg/ml and 0.5338 mg/ml, the limit of quantitation value obtained was 0.9004 mg/ml and 1.6176 mg/ml, the range for both was 80% to 120%, and the specificity for both met the requirements. 5. acknowledgment the authors would like to acknowledge universitas tjut nyak dhien for research funding and industri farmasi mutiara mukti farma for tools and materials support. references akbel, e., s. güngör, and i̇. bulduk (2022). alternative analytical methods for ibrutinib quantification in pharmaceutical formulation: a statistical comparison. reviews in analytical chemistry, 41(1); 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revised 20 january 2018; accepted 20 january 2018 http://doi.org/10.26554/sti.2018.3.1.35-40 bioremediation of spent bleaching earth (sbe) wastes using lipolytic bacteria (bacillus cereus) with variation of inoculum volume maria lusia1, nuni gofar2, hary widjajanti3 1department of environmental management graduate school sriwijaya university, jl. padang selasa, no. 524, bukit besar, palembang, indonesia 2department of soil science, faculty of agriculture, sriwijaya university. 3department of biology, faculty of mathematics and natural sciences, sriwijaya university abstract spent bleaching earth (sbe) is a solid waste was generated from the cpo refining step into cooking oil. sbe that was discharged directly into the environment has the potential to pollute the environment because in the sbe waste contained oil and acid residues, which are easy to be oxidized and flammable. therefore, sbe must be processed first before being discharged into the environment. one way to manage sbe waste is by bioremediation. bioremediation is a method of cleaning the environment from contaminants by using biological agents, such as bacteria, fungi, etc. the bacterial isolates used in this study were bacillus cereus. this study aims to obtain the best inoculum and to know the ability of bacillus cereus bacteria in degrading the oil content in spent bleaching earth (sbe) waste. this study used a completely randomized design with the volume of bacillus cereus bacteria inoculum as a treatment, consisting of 6 treatment levels of 0 ml kg-1, 25 ml kg-1, 50 ml kg-1, 75 ml kg-1, 100 ml kg-1 and 125 ml kg-1. each treatment level was repeated 3 times so that 18 experimental units were obtained. the observation was done once a week, in a month. parameters observed were bacterial population, the percentage of oil degradation and oil content after degradation. the best treatment result for the bacterial population was obtained at the treatment of 100 ml kg-1, at week 4, which was 7.4 x 108 cfu g-1, and for the oil, degradation was obtained at 50 ml kg-1 on the treatment at week 4 as big as 90.43%. keywords: spent bleaching earth (sbe), bacillus cereus, bioremediation, degradation 1. introduction indonesia is the second largest of palm oil producer in the world. cpo that was produced from palm oil can be used for various industries including cooking oil industry. based on a survey conducted by cdmi (2014), indonesia’s cooking oil production in the last five years (2009-2013) increased by an average of 16.5% per year from 7.13 million tons per year in 2009 to 13.0 million tons per year in 2013. the processing of cpo into cooking oil is carried out through various stages. one of the stages in the refining stage, which consists of degumming, bleaching, filtration, deodorization, and deaeration. each stage is producing residues (wastes). the most massive wastes were contained in the bleaching process (purification). the waste generated from the bleaching process is a solid waste known as spent bleaching earth (sbe). according to prokopov & mechenov (2013), sbe is generated from the bleaching process that is disposed of as waste in landfills. the disposal of sbe on landfill can lead to environmental pollution. sbe contains oil residues that are easy to be oxidized and flammable. kheang et al. (2006), states that each sbe particle contains an average of absorbed oil derived from the bleaching process of cpo, which is contained of 20-30% from the weight of sbe. regarding the vast amount of oil were still left behind, the management of sbe requires particular attention in order to reduce the impact on the environment. one of the ways to process the sbe waste is by bioremediation method, by utilizing biological agents such as bacteria. bacteria that can be used in reducing oils residue are classified as lipolytic bacteria. lipolytic bacteria produce and excrete lipase enzymes that can hydrolyze fat to fatty acids and glycerol. based on previous research conducted by widjajanti and munawar (2015), one of the bacteria that can reduce oil in sbe waste is bacillus cereus bacteria. this bacterium is able to reduce the oil in sbe waste by 49.06%. biodegradation by bacillus cereus bacteria is influenced by biotic and abiotic factors, including bacteria, substrates, nutrients, acceptor and environmental factors, such as ph, temperature and salt content (notodarmojo, 2005). nugroho (2006), adding that lucia et al. 2018 / science & technology indonesia 3 (1) 2018: 35-40 36 the degradation process of a compound is caused by the enzyme product produced by the bacteria, so the degradation process depends on the number of bacteria sufficient to degrade the oil through its metabolic pathway. as one of the factors that influence the bioremediation process, it is necessary to research about the right concentration of inoculum so that the bioremediation process is going well. this study aims to obtain the best inoculum volume and to know the ability of bacillus cereus in sbe waste bioremediation. 2. experimental section 2.1 materials and instrumentation the tools were being used in this research are stationery, aluminum foil, autoclave, bunsen burner, petri dish, tissue, erlenmeyer, beaker, measuring cylinder, hot plate, incubator, ose needle, digital camera, cotton, filter paper, label paper, refrigerator, ph meter, stirrer, magnetic stirrer, paper disk, micron pipette, serological pipette, basin, plastic, rubber, reaction tube rack, rotary shaker, reaction tube, analytical scales, vortex, microscope, counting chamber, and soil tester. the materials were being used are aquadest, the bacterial isolates of bacillus cereus, mineral medium, na medium, nb medium, 70% alcohol, and sbe waste. 2.2 sampling method this study used a completely randomized design (ral) with the treatments of bacterial inoculum of bacillus cereus, which consisted of: 0 ml kg-1 (control), 25 ml kg-1, 50 ml kg-1, 75 ml kg-1, 100 ml kg-1 and 125 ml kg-1. each treatment was repeated 3 times. 2.3. procedure 2.3.1 sampling sampling was done at pt. tunas baru lampung, south sumatera. sbe waste samples were taken directly from the drainage stack using randomizes sampling, as much as 50 kg. sample of wastes were solid wastes, grayish black, smells sharp and flammable. 2.3.2. sterilization tools and media the tools and media that being used were sterilized by autoclaving at 1 atm pressure at 121oc for 15 minutes and the nonheat resistant equipments were sterilized using 70% alcohol. 2.3.3. medium creation 2.3.3.1 na medium (nutrient agar) the na medium (nutrient agar) was weighed 1.2 g and then dissolved in 60 ml of aquades in erlenmeyer. erlenmeyer which contain the media was clogged with cotton and aluminum foil, and then was heated over the hot plate until the solution becomes light yellow, next was sterilized in the autoclave at a temperature of 1210c pressure 1 atm for about 15 minutes. as much as 10 ml of nutrient agar was inserted to the reaction tube amounting of 6 pieces, settled at room temperature until the media freezes in a tilted position, and then the tilted nutrient agar is ready for bacterial rejuvenation. 2.3.3.2. making nb medium nb medium (nutrient broth) was 13 g and dissolved in 1000 ml of aquades, then being heated until dissolved, and cooled first, and the tube was covered with cotton and aluminum foil. the nutrient broth solution was being heated in the autoclave to 1210c at 1 atm pressure for 15 minutes and then stored in the refrigerator. 2.3.3.3. making of mineral medium making mineral medium by dissolving k2hpo4 4.5g; (nh4) 2so4 1 g; 7h2o 0.2 g; nacl 0.1g; cacl2 0.1 g; fecl3 0.02 g and cpo 44.3 ml into 1000 ml of aquades on erlenmeyer. the solution was homogenized by using a magnetic stirrer over the hot plate. after homogeneous, the media was sterilized using an autoclave at a temperature of 121oc with a pressure of 1 atm for 15 minutes (modifikasi atlas, 2010). 2.3.4. rejuvenation of lipolytic bacteria lipolytic bacterial isolates were inoculated into a prepared nutrient agar (na) medium, i.e. as many as 6 reaction tubes. the bacterial isolate was taken by using an ose needle aseptically, and taken as much as 1 ose, and then the cultured ose needle was placed at the base of the slope of agar and withdrawn with zigzag movement (modifikasi lay, 1994), then being incubated in the incubator for ± 48 hours at room temperature. 2.3.5 growth curve of lipolithic bacterial growth the growth curve of bacterial isolate was made by inoculating as much as 4% (v/v) bacterial inoculum on 100 ml of mineral medium, which was added by the cpo. the number of bacterial cells was calculated from the time of initial inoculation until it showed the decreased of cell density with observation intervals every 3 hours, whereas the diagitation cultures were at 120 rpm at room temperature, and the calculations were performed direct microscopically by counting chamber. the number of isolate cell data for each observation was presented in graphical form, so that the growth phases are being known. the obtained isolate growth curve was determined as the shortest generation time in its exponential growth phase. the shortest generation time was used as the basis for making and giving inoculum on testing the ability of bacteria to degrade the sbe waste. the equations used to determine generation time are: description : g = generation time t = time interval between measuring the number of cells in the population at a time in the log phase (b) and then again at a later point (b) b = initial population b = population after time t log = log10 3.3 = conversion factor log2 to log10 (pelczar and chan, 2010). the shortest generation time was obtained according to the bacterial growth curve is 6 hours. 2.3.6 inoculum making of lipolytic bacteria the making of bacterial inoculum by taking the cultured of the rejuvenated bacterial isolates, as much as 15 ose, then inserted lucia et al. 2018 / science & technology indonesia 3 (1) 2018: 35-40 37 into 2400 ml of nb medium, nb medium containing bacterial isolates were being homogenized by rotary shaker for 6 hours (according to the shortest time in bacterial growth curve), after 6 hours, calculated the density of bacteria by using counting chamber, then calculated until the density of ±108 cells/ml. once the bacterial density is in accordance with the desired, then, the bacterial inoculum is ready to be inoculated into the bioreactor. 2.3.7. bioreactor preparation for bioremediation bioreactor prepared as many as 18 pieces. each bioreactor was filled with 2 kg of spent bleaching earth (sbe) waste, with a predetermined waste treatment condition, i.e. for ph 6-7, and 50% moisture. the ph measured at the start of the study was 3.11 (very acidic). the ph was raised by calcification. lime that being used was calcite chalk type (caco3), as much as 1.08 kg for 50 kg of sbe waste. after the lime is applied to the sbe waste, it was homogenized by stirring, after homogenous then covered by plastic for 2 weeks. after 2 weeks, ph was measured again by using ph meter, and obtained ph value of 5.89. furthermore, moisture was measured using a soil tester. at the time of bioreactor preparation, the moisture has reached at 50%. after the prepared bioreactor was in accordance with the desired conditions, the prepared bacterial inoculum was ready for inoculation into each bioreactor according to the treatment (0 ml kg-1, 25 ml kg-1, 50 ml kg-1, 75 kg-1, 100 ml kg-1, 125 ml kg-1). the bacterial inoculum was inoculated by using spray evenly over the entire portion, and then being homogenized again by stirring so that it was completely mixed. then each bioreactor was covered by a plastic that has been perforated and finally the bioreactor was placed in a sterile place (to avoid contaminants). furthermore, the bioreactor was allowed to stand for one month with intervals of observation and controlling the moisture in every week. 2.3.8. analysis of gravimetric oil levels the oil content was analyzed by gravimetry according to reference of sni 06-06989-10 which has been modified. the oil content analysis was carried out by inserting 5g of sbe into the erlenmeyer, 100 ml of n-hexane was added and then shaken for ± 5 min using a shaker, then the shaked sbe and n-hexane were filtered with filter paper in a weighted bottle. there are 3 layers of oil, n-hexane and water. the water layer was disposed; the oil layer and n-hexane were inserted into the distillation flask, then disoxhlet until n-hexane runs out. the flask was heated in the oven at 100°c for 1 day until n-hexane runs out, the water runs out and only the oil was left. the flask was lifted and settled in the desiccator for 30 minutes. make sure the flask is dry and weigh until it gets a fixed weight. the formula for calculating the oil content is: % oil contents = (a-b) x 100% gram sample description: a = weight of flask and extract (g) b = empty flask weight (g) (sni 06-06989-10, 2004) 2.3.9. calculation of bacterial population the calculation of bacterial colonies used by the total plate count (tpc) method. the sbe was taken from the bioreactor and weighed 5 g, then added 45 ml of aquadest. then perfomed dilutions of 6 series (10-1, 10-2, 10-3, 10-4, 10-5 10-6). from the 6 series dilutions, only 3 dilution series (10-4, 10-5, 10-6) were taken to be placed on a sterile petri dish for each treatment. then the na medium is poured into an existing substrate petri dish, and then incubated for 24 hours at 37 ° c. the result of bacterial population contained in petri dish is calculated by using colony counter. 2.4 variable observations observation variables observed in this study are as follows: 2.4.1. bacterial population the bacterial population at each treatment was calculated in cfu g-1 every one week from once for 4 weeks. 2.4.2 percentage of oil content the calculation of the oil content of the sample in units of% (%) is done once a week for a month to find out how much oil content is left in the sbe waste. 2.4.3 percentage of oil degradation the calculation of oil degradation was done once a week in a month to determine the residual oil lost during the bioremediation process. calculation of the degradation percentage of oil content by using equation as follows: percentage of oil degradation = a b x 100% a description: a = initial oil content (%) b = final oil content (%) 2.5 data analysis the data which was obtained include bacterial population data, percentage of oil degradation, composition and compounds contained in sbe waste. bacterial population data and percentage of oil degradation were being analyzed by using variance analysis (anava) and if it was significantly different, then continued with duncan new multiple range test (dnmrt) test with α 5%. the data was being analyzed using software statistic 8.0. 3. result and discussion the result of varian analysis (anava) showed that the volume of bacterial inoculum of bacillus cereus had a significant effect on bacterial population, oil content and oil degradation. further test results of dnmrt α5% on the variations of inoculum volume on bacterial population, oil content and oil degradation are presented in table 3.1, 3.2 and 3.3. 3.1 bacterial population the best inoculum volume treatment for bacterial population was 100 ml kg-1 at week 4, i.e, 7.74 cfu g-1. these results indicate that at these concentrations support for optimal bacterial growth. furthermore, in table 3.1 there was an increase in the number of bacterial cells along with the increase of inoculum volume, although the increasing result did not affect the significant differences between treatments. this explains that the treatment of large amounts of lucia et al. 2018 / science & technology indonesia 3 (1) 2018: 35-40 38 inoculum did not guarantee the number of bacterial cells more than the treatment of fewer inoculums. the results of zam (2010) showed that there was no correlation between giving a large amount of inoculum to the growth of microorganisms. according to doelle (1994), sufficient inoculum concentration is one of the requirements that the fermentation process can take place optimally. the increasing of bacterial population at 25 ml kg-1, 50 ml kg-1, 75 ml kg-1, 100 ml kg-1 and 125 ml kg-1 acts every week during the bioremediation process. this suggested that bacteria have been able to utilize the nutrients present in the substrate and be able to adapt to the substrate environment. in the first weeks, bacteria were still in the adaptation stage, i.e. bacteria still in the preparation stage and adjustment to environmental growth conditions, such as nutrient source conditions and substrate environmental conditions. susanti (2003), stated that in the adaptation phase to the environment the bacteria will hydrolyze the required medium components for metabolism and cell growth. according to kusumaningati et al. (2013), in the slow phase (lag phase) bacteria perform metabolism in preparing and adjusting to the growth conditions in new environments so that there is no significant increase in the number of cells. in the adaptation stage, the increasing of cell activity will continue, along with the improvement of the absorption of nutrients as a source of energy. waluyo (2007), stated that the better the bacteria absorb the nutrients contained in the substrate, then the growth of bacterial numbers is getting faster. after the adaptation stage, bacterial growth will enter the exponential phase. in this phase the bacterial cell will reach the highest number (climax), and then it will decrease or stagnate. kusumaningati et al. (2013), stated that the exponential phase is the phase of cell number multiplication, cell activity increases. the bacterial population at week 3 were continues to increase, showed that the 25 ml kg-1 treatment has entered the exponential phase. bacterial population at 4th week, seen began to decrease or becoming stagnated. bacterial growth at 4th week was in the stationary phase. in this phase, the source of nutrients that were available carbon is getting more and more exhausted because it has been exploited by bacteria as a food source. susanti (2003), stated that in the phase of death, the nutrients was being needed by bacteria are reduced and the results of bacterial excretion have been buried in the medium, thus disrupting the breeding and the next bacterial growth. anggriani et al. (2012), stated that the factors that cause the death of microbial population are the nutrients in the medium are exhausted and no reserve energy in the cell. therefore the bacterial cell growth will decrease or has a tendency to be stagnant. 3.2 oil content the results of this study indicate that there was a decrease in oil levels for all treatments along with the increasing of the volume numbers of inoculum in each week of observation, although the difference in oil levels among treatments were significant and insignificant. preliminary data of oil content in sbe waste before inoculation was 7%. presumably this is caused by a certain amount of inoculum, the bacteria have been able to decompose the oil optimally. januar et al. (2013), stated that the decrease in lipid levels is an indication of the role of bacteria in oil remodel. mishra et al. (2001), stated that the suitability between the inoculum ratio and the substrate composition can affect the petroleum degradation process. the degradation of oil content came along with the length of time of bioremediation (table 3.2). presumably this is caused by the lack of nutritional sources along with the length of bioremediation, thus causing a competition in getting food. this competition leads to the death of bacteria, so the number of bacteria is reduced, eventually the degradation process also decreased. according to chorom et al. (2010), that time has a significant effect on the degradation process. schaefer and juliane (2007) suggested that the longer the bioremediation time, the growth of bacteria and the rate of degradation of oil were being decreased. furthermore, if we refer to the decree of kepmen lh no. 128 (2003), it can be seen that the 125 ml kg-1 treatment with the value level of oil as much as 0.83% at week 2, has fulfilled the requirements set by the government that is at a maximum of 1%. and if the bioremediation process was continued for up to three weeks, the 75 ml kg-1 treatment is a treatment that can be applied with a 0.76% oil content, and if the bioremediation process were being continued until week 4, then 50 ml kg-1 treatment with the oil content of 0.67 is a usable treatment. 3.3. percentage of oil degradation the result of the percentage of oil degradation showed that the greater of the inoculum volume, the higher the percentage of degradation obtained, although, there were significant and insignificant differences among treatments. the percentage of degradation will increase along with the decrease of oil content. according to zulaika et al. (2012), the higher of the number of cells were being used; the resistance and the reduction power of bacillus will be higher. nugroho (2006), stated that the degradation process of a compound is caused by the enzyme product produced by bacteria, so the degradation process depends on the adequate amount of bacteria to degrade the oil through its metabolic pathway. atlas and bertha (1992) suggested that the remodel activity is caused by enzyme oxygenase released by bacteria to increase direct contact between oil and bacteria, so bacteria can use the oil as a carbon source. furthermore, table 4.3 also showed that although the percentage of degradation increased along with the increasing of intable 1. the average (log) population of bacillus cereus lipolytic bacteria on each treatment volume of inoculum population lipolytic bacteria on week of (cfu g-1) (ml/kg¯¹) 1 2 3 4 0 1,00 a 1,00 a 1,00 a 1,00 a 25 3,90 ab 4,90 ab 7,40b 7,43 b 50 4,13 ab 4,99 ab 7,63bc 7,52 b 75 5,96 b 5,46 ab 7,88 bc 7,52 b 100 6,33 b 7,89 b 7,92 bc 7,74 b 125 6,38 b 7,92 b 8,03 c 7,87 b note: letter indexed after values are duncan multiple rang test category table 2. the average of oil content after degradation in each week of observations volume of inoculum oil level on the week of (%) (ml/kg¯¹) 1 2 3 4 0 3,52 a 3,07 a 2,67 a 1,82 a 25 2,32 b 2,26 b 1,22 b 1,11 ab 50 1, 95 bc 1,25 c 1,15 b 0,67b 75 1,78 bcd 1,39 c 0,76 b 0,35 b 100 1,52 cd 1.13 c 0,70 b 0,39 b 125 1,13 c 0,83 c 0,76 b 0,72b note: letter indexed after values are duncan multiple rang test category lucia et al. 2018 / science & technology indonesia 3 (1) 2018: 35-40 39 oculum volume in every week of observations, the statistic showed that the increase was not significantly different among treatments. presumably, this is because the concentrations of bacteria are causing inadequate medium for the bacterial growth, effected to the competition between the bacteria, and eventually the growth and degradation process becomes low. astuti (2003), stated that the competition in the use of substrate effected to the growth of culture becomes poor, because the increasing of cells number or biomass become low. according to gibbson and westby (1986), too high inoculum concentrations can lead to a reduction in cell viability. anggriani et al. (2012), adding that too high bacterial populations can lead to the rivalry of the similar types of bacteria (bacillus sp) and indigenous microorganisms in nutrient or substrate intake that eventually the bacterial activity become inhibited. inoculum volume of 50 ml kg-1, is the appropriate and economical inoculum volume treatment in sbe waste bioremediation. the treatment supports for optimal bacterial growth when being compared with other treatments. the correlation analysis between the bacterial population and the percentage of degradation indicates the bacterial population affects the percentage of degradation. the correlation analysis between the bacterial population and the degradation percentage yielded a correlation coefficient (r) of 0.6006. the correlation coefficient value between the bacterial population and the percentage of degradation is positive; it means the relationship between the bacterial populations (cfu g-1) was in line with the percentage of degradation. if the population of bacteria (cfu g-1) (x) is high then the percentage of degradation produced is also high and the oil content (%) will decrease. according to ichor et al. (2014), stated that the number of bacterial cells responsible to the oil degradation. the results of simple linear regression analysis showed that the association of the bacterial population and the percentage of degradation can be seen in the following equation: y = 63.072 + 2.828x description: y: percentage of oil degradation x: bacterial population the simple linear regression equation showed that the bacterial population (cfu g-1) was influenced by the constant 63,072 and the regression coefficient + 2,828. the regression coefficient is positive value, then the regression model is positive or in line with the direction of the percentage of oil degradation (%). based on linear regression equation above can be concluded that bacterial population (x) have the positive effect on degradation percentage with total influence of 35,9%. this positive influence means the higher of the bacterial population; the higher of the percentage of degradation. this relationship is also seen in the linear graph between the bacterial population and the percentage of degradation (figure 1). 4. conclusion the volume of inoculum affected to the bacterial growth and oil degradation. the best treatment of bacterial inoculum volume of bacillus cereus to the bacterial population is 100 ml kg-1 at week 4 of 7.4 x 108 cfu g-1 and the most efficient treatment in degrading oil in sbe waste during the bioremediation process, was the inoculum volume of 50 ml kg-1 treatment at week 4 as much as 90.43%. references anggriani, r., iskandar dan ankiq, t., 2012. efektivitas penambahan bacillus sp. hasil isolasi dari saluran pencernaan ikan patin pada pakan komersial terhadap kelangsungan hidup dan pertumbuhan benih ikan nila merah (oreochromis niloticus). jurnal perikananan dan kelautan. 3 (3): 75-83. astuti, d.i. 2003. pemanfaatan kultur campur isolat mikroba lokal untuk degradasi minyak bumi dan produksi biosrufaktan. disertasi doktor institut teknologi bandung, bandung. atlas, r. m., and bartha, r. 1992. microbial ecology. benyamin cummings science, california. cdmi consulting. 2014. http://www.cdmione.com/product. php#cpo2014. opened 20 desember 2016. chorom, m., sharifi, h.s. and moamedi, h. 2010. bioremediation of a crude oil polluted soil by application of fertilizers. iran. j. environ. health. sci. eng. 7 (4) :319-326. doelle, h.w. 1994. microbial process development. world scientific publishing co.pte.ltd. singapore. ichor, t., okeruntugba, p.o. and okpokwasili, g.c. 2014. biodegradation of total petroleum hydrocarbon by aerobic heterotrophic bacteria isolated from crude oil contaminated brackish waters of bodo creek. journal bioremed biodeg. 5(5):16. januar, w., khotimah, s., dan mulyadi, a. 2013. kemampuan isolat bakteri pendegradasi lipid dari instalasi pengolahan limbah cair ppks ptpn-xiii ngabang kabupaten landak. jurnal protobiont. 2(3): 136-140. keputusan menteri lingkungan hidup no.128 tentang kadar minyak. 2003. kheang, s. i. cheng, s. f. choo, y. m. dan ma ah ngan. 2006. a study of residual oils recovory from spent bleaching earth. their characteristics and applications. american jurnal of applied sciences. 3(10): 2063-2067.wijs dan hanus. kusumaningati, m.a., sri n, anton m. 2013. pengaruh konsentrasi inokulum bakteri zymonas mobilis dan lamanya fermentasi pada produksi etanol dari sampah sayur dan buah pasar wonokromo surabaya. jurnal saint dan seni pomits. vol 2. (2) table 3 average percentage of oil degradation (log) at each treatment at week 1,2,3,4 after application volume of inoculum percentage of oil degradation (%) on week of (ml/kg¯¹) 1 2 3 4 0 50,43 a 56,04 a 61,86 a 70,05 a 25 66,76 b 67,71 b 82,57 b 84,14 ab 50 72,13 bc 80,09 c 83,53 b 90,43 b 75 74,57 bcd 80,43 c 89,19 b 94,95 b 100 78,33 cd 83,86 c 90,00 b 94,38 b 125 83,81 d 88,14 c 89,19 b 89,72 b note: letter indexed after values are duncan multiple rang test category figure 1. simple linear regression graph between the bacterial population and the percentage of degradation lucia et al. 2018 / science & technology indonesia 3 (1) 2018: 35-40 40 2337-3520. lay, b.w. 1994. analisis mikroba di laboratorium. pt. raja grafindo persada. jakarta:xvii + 167 hlm. mishra, s.j. jyot, r.c., kuhad, and b. lal. 2001. evaluation of inoculum addition to stimulate in situ bioremediation of oily sludge contaminated soil. app. and environ. microbiol. 67 (4), 1675-1681. nugroho, a., 2006. biodegradasi sludge minyak bumi dalam skala mikrokosmos: simulasi sederhana sebagai kajian awal bioremediasi land treatment. makara teknologi 10 (2): 82-89. notodarmojo, s. 2005. pencemaran tanah dan air tanah. penerbit itb. bandung.: viii + 488. prokopov, t. and mechenov, g. 2013. utilization of spent bleaching earth from vegetable oil processing. ukrainian food journal.2(4): 489-498. schaefer, m. and juliane, f. 2007. the influence of earthworms and organic additives on the biodegradation of oil contaminated soil. applied soil ecology. 36(2): 53-62. susanti, e. v.h. 2003. isolasi dan karakterisasi protease dari bacillus subtilis 1012m15. jurnal biodiversitas, 4(1): 12-17. widajanti, h dan munawar. 2015. pengelolaan spent bleaching earth dengan bioremediasi menggunakan bakteri lipolitik indigen. laporan hibah fundamental tahun i. lembaga penelitian universitas sriwijaya. waluyo l. 2007. mikrobiologi umum. penerbit universitas muhamaddyah press, malang. w. r. gibbson and c. a. westby, “effect of inoculum size on solid-phase fermentation of fodder beets for fuel ethanol production”. journal applied and environmental microbiology vol. 52 (1986) 960-962. zam, s.i. 2010. optimasi konsentrasi inokulum bakteri hidrokarbonklastik pada bioremediaso limbah pengilangan minyak bumi di sungai pakning. journal of environmental science. 2010 : 2(4). zulaika, e., umi s.,dan yulianto a.d., 2012. potensi bakteri bacillus sebagai agensia bioremediasi limbah industri yang mengandung merkuri. seminar pemetaan potensi dan inovasi ilum pengetahuan, teknologi, seni dan budaya (ipteksb), surabaya: ristek its. title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper antibacterial and antioxidant activity of endophytic fungi extract isolated from leaves of sungkai (peronema canescens) rian oktiansyah1,2, hary widjajanti3, arum setiawan3, sakinah salman ahmad nasution4, mardiyanto5, elfita4* 1graduate school of sciences, faculty of mathematics and natural sciences, university of sriwijaya, palembang, 30129, indonesia2universitas islam negeri raden fatah palembang, palembang, 30267, indonesia3department of biology, faculty of mathematics and natural sciences, university of sriwijaya, ogan ilir, 30662, indonesia4department of chemistry, faculty of mathematics and natural sciences, university of sriwijaya, ogan ilir, 30662, indonesia5department of pharmacy, faculty of mathematics and natural sciences, university of sriwijaya, ogan ilir, 30662, indonesia *corresponding author: elfita.elfita.69@gmail.com abstractsungkai is a plant that is widely found in indonesia. this plant is often used in traditional medicine so the biotechnology of endophyticfungi is highly needed due to natural resources from plants that have been reduced. this study reported on endophytic fungi foundin sungkai leaves and the compound produced. morphological and molecular identification through phylogenetic tree analysis wascarried out to determine the endophytic fungal species found. potato dextrose broth media was used for the cultivation process.ethyl acetate was used as a solvent for the extraction and the evaporation process used a rotary evaporator. antioxidant andantibacterial tests were carried out using the dpph method and paper disc diffusion. chromatographic techniques were used toisolate the compound and spectroscopic analysis was performed to identify its chemical structure. the results of the morphologicaland molecular analysis showed trichoderma asperellum as an endophytic fungus identified. the pure compound obtained from thisendophytic fungus was 4-hydroxybenzoic acid. the antioxidant and antibacterial activity showed a strong category (ic50 = 43.88 `g/ml; mic 64 `g/ml). this compound was very likely to be a raw material for new antibiotics and antioxidants through furtherresearch with various modifications. keywordsbioactive compound, endophytic fungi, trichoderma asperellum, sungkai received: 7 november 2022, accepted: 25 january 2023 https://doi.org/10.26554/sti.2023.8.2.170-177 1. introduction during the covid-19 pandemic, sungkai leaf is a plant that is believed by the community, especially in south sumatra (indonesia), to increase immunity. the secondary metabolites contained in the sungkai plant, namely flavonoids, peronemin, isopropanol, betulinic acid, peronemin, and sitosterol are efficacious as antioxidants and antibacterials in which this bioactivity mechanism can increase the immune system (dillasamola et al., 2021; latief, 2021). however, the cultivation of medicinal plants faces many obstacles that reduce plant populations and exploration is needed to find new sources of raw materials for medicinal needs, such as biotechnology of endophytic fungi. the biotechnology of endophytic fungi is a technology that uses fungi living on plant tissues without harming their hosts (el hawary et al., 2020; mbilu et al., 2018). the interesting variety of chemical structures and bioactivity make endophytic fungi a promising focus for natural products (tiwari and bae, 2020; wen et al., 2022). studies have revealed that endophytic fungi produce secondary metabolites with diverse bioactivities such as antibiotics, antiprotozoals, antivirals, antidiabetics, antiparasitics, anticancers, antioxidants, and immunomodulatory compounds so that endophytic fungi are referred to as secondary metabolite stores (khan et al., 2019; manganyi and ateba, 2020). trichoderma is a genus of endophytic fungi that have diverse bioactivity (morais et al., 2022; zhang et al., 2021). trichoderma has a good adaptive ability to the environment and its growth rate is much faster. trichoderma can produce various secondary metabolites, such as isonitrile, diketopiperazine, sesquiterpenes, polyketides, alkylpyrone, and peptaibol (khan et al., 2020; wu et al., 2017). it has proven that 6-pentyl𝛼-pyron, which is produced by t. harzianum and t. hamatum, efficiently has antioxidant and antibacterial properties against acidovorax avenae, erutimcarafavora, and xanthomonas campestris (al rajhi et al., 2022; baazeem et al., 2021). t. asperellum is https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.170-177&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.170-177 oktiansyah et. al. science and technology indonesia, 8 (2023) 170-177 also known to contain compounds such as alkaloids, tannins, phenolics, triterpenoids, and flavonoids which effectively have bioactivity, such as antipyretic, antibacterial, anticancer, and antioxidant (gu et al., 2022; karuppiah et al., 2019; scudeletti et al., 2021; singh et al., 2021). secondary metabolites from endophytic fungi can be used as relevant sources of raw materials for new medicine. research shows that the bioactive metabolites obtained have a unique chemical structure. these endophytic fungi are able to produce similar metabolites or new compounds that are different from their host (cruz et al., 2020; el hawary et al., 2020). this event is a potential that can be developed from this group of microbes for the discovery of new drugs. 2. experimental section 2.1 sample preparation and isolation of endophytic fungi the sample obtained was identified at the plant systematics laboratory, university of sriwijaya with number 302/un9.1.7 /4/ep/2021. the fresh leaves used were in the fourth position from the primary branch. the surface of the leaves was first sterilized before the isolation of the endophytic fungi by washing it with water for ± 5 minutes. next, the sample was immersed in alcohol 70% for ±3 minutes, rinsed with sterilizeddistilled water for ±1 minute, and immersed in 3% naocl solution for 1 minute. for the inoculation, the sample was first cut aseptically ± 3 x 1 cm before being inoculated into a petri dish containing pda. the inoculants were incubated for 3-14 days at room conditions. purification of fungi endophyte by transferring the colonies to a new petridish containing media and incubating at room temperature for 48 hours (setiawan, 2022; hapida et al., 2021). 2.2 characterization and identification of fungal endophytes morphologically phenotypic characters were used to identify endophytic fungi. the slide culture method was used to observe microscopic characteristics with 1000x in magnification. the phenotype characteristics (macroscopic and microscopic) that emerged were then compared with several references (books and journals) for identification requirements (pitt and hocking, 2009;walsh et al., 2018; watanabe, 2002). 2.3 molecular identification of fungal endophytes molecular identification was carried out based on the endophytic fungal isolates with the most potential bioactivity. the identification used the its dna (rdna) area. the amplification process used primers its1 (5’-tccgtaggtgaacctg cgg-3’) and its 4 (5’-tcctccgcttattgatatgc-3’). the sequences are included in blast (http://blast.ncbi.nlm.nih .gov/blast.cgi). furthermore, the clustal w method (in the mega11 program) was used to align the sequences and the neighbour-joining tree method was used to construct a phylogeny tree with a bootstrap value of 1000 (tamura et al., 2013) . 2.4 cultivation and extraction cultivation was carried out by placing 6 blocks of agar (6 mm in diameter) the pure culture of each endophytic fungal isolate obtained was placed in 300 ml potato dextrose broth media. the isolate was cultivated in 15 glass bottles (volume 1 l). then, the cultures were incubated for 30 days statically at room condition. the medium was separated from the fungal biomass using filter paper and the solvent ethyl acetate was added to the culture medium with the ratio of 1:1. after 10 days, the extracts were separated using a rotary evaporator (habisukan et al., 2021) . 2.5 antioxidant activity test the antioxidant activity used the dpph method based on baliyan et al. (2022) , that was 0.2 ml of each extract concentration was added 0.5 mm dpph solution volume 3.8 ml. the blend solution was incubated in a dark tube for 30 minutes. the absorbance was measured at 517 nm using a spectrophotometer and ascorbic acid was used as a standard. the percentage of inhibition and ic50 value were calculated to determine antioxidant activity (abbas et al., 2021) . %inhibition = ak − as as × 100% (1) ak = control as = samples 2.6 antibacterial activity test the test of antibacterial activity used the paper disc diffusion method. the media used is mha (muller hinton agar). the test bacteria used were escherichia coli inaccb5, salmonella typhi atcc1048, bacillus subtilis inaccb120, and staphylococcus aureus inaccb4. the blank disc paper was dripped with the concentration of 256, 128, 64, 32, 16, 8, and 4 `g/ml to test the minimum inhibitory concentration (mic). the mic value showed <100 `g/ml belonged to strong antibacterial (ding et al., 2019) . 2.7 isolation and identification of compound the most potential extract was prepared by preabsorption and put into the chromatographic column. next, the extract was eluted by using eluent upon increasing polarity. the eluate was collected to a 10 ml vial and a tlc test was carried out to be grouped into column fractions. pure compounds were obtained through the process of evaporation, separation, and purification of column fractions with chromatographic techniques. the compound structure identification used 1d and 2d nmr spectroscopy method which included 1h-nmr, 613c-nmr, hmqc, hmbc and compared with the nmr data of the same compound from reference. 3. result and discussion 3.1 isolation and identification of fungal endophytes this research was the continuation by re-isolating sd8 from sungkai leaves at the fourth position from the primary branch, © 2023 the authors. page 171 of 177 oktiansyah et. al. science and technology indonesia, 8 (2023) 170-177 figure 1. morphology of t. asperellum found in sungkai leaves (a. front view; b. reverse view; c. microscopic characteristic) a different position from previous studies. furthermore, morphological and molecular identification was carried out on sd8 isolate. macroscopic characteristics showed colonies with white greentint, cottony, umbonate, and radiate while microscopic characteristics showed conidiophores hyaline, short and thick phialides, and globose. colony turned green with the age (figure 1). molecular identification showed that the isolate sd8 was trichoderma asperellum with 100% similarity. the phylogenetic tree can be seen in figure 2 with the sequence as follows: tgcggagggatcattaccgagtttacaactcccaaa cccaatgtgaacgttaccaaactgttgcctcggcgg ggtcacgccccgggtgcgtcgcagccccggaaccag gcgcccgccggaggaaccaaccaaactctttctgta gtcccctcgcggacgtatttcttacagctctgagca aaaattcaaaatgaatcaaaactttcaacaacggat ctcttggttctggcatcgatgaagaacgcagcgaaa tgcgataagtaatgtgaattgcagaattcagtgaat catcgaatctttgaacgcacattgcgcccgccagta ttctggcgggcatgcctgtccgagcgtcatttcaac cctcgaacccctccgggggatcggcgttggggatcg ggacccctcacacgggtgccggccccgaaatacagt ggcggtctcgccgcagcctctcctgcgcagtagttt gcacaactcgcaccgggagcgcggcgcgtccacgtc cgtaaaacacccaactttctgaaatgttgacctcgg atcaggtaggaatacccgctgaacttaagcatat trichoderma asperellum is a type of fungus that is highly adaptive to the environment. the growth rate tends to be faster than other fungi so that they can fight with nearby pathogens for defined space and nutrients (stracquadanio et al., 2020; tyśkiewicz et al., 2022; zin and badaluddin, 2020). therefore, this fungus is often used as a biocontrol of pathogenic fungi in the environment. research reveals that t. asperellum can be found in all parts of the plant because it is easy to spread and no research evidence reports on the specific tissue where it grows (el_komy et al., 2015; lahlali et al., 2022). endophytic fungi isolated from plants, especially medicinal plants, usually have good biological activity. the ability of endophytic fungi to synthesize secondary metabolites is used by host plants for defense and can be used as alternative raw materials for medicines. research on t. asperellum from other figure 2. phylogeny tree of sd8* constructed by using neighbour-joining with bootstrap of 1000 plants has been carried out to reveal its secondary metabolites which have anti-inflammatory, antimicrobial, and antioxidant activities (sharma et al., 2021; singh et al., 2021). 3.2 bioactivity of fungal endophyte the antioxidant and antibacterial activity of ethyl acetate extract and pure compound of t. asperellum compared with ascorbic acid and tetracycline as standard can be seen in table 1. table 1 shows the results of the antioxidant and antibacterial properties tests of the ethyl acetate extract of the endophytic fungus t. asperellum, and its compound. the results showed that the compounds obtained had strong antioxidant activity (ic50 < 100 `g/ml) and strong antibacterial activity contrary to all test bacteria (mic ≤ 64 `g/ml). these results indicate that the compounds obtained have the potential to be developed into new materials for pharmaceuticals. the ethyl acetate extract of t. asperellum showed moderate antibacterial activity against e. coli and s. aureus (mic = 128 `g/ml) and a strong category for s. thypi and b. subtilis (mic ≤ 64 `g/ml). its antioxidant activity also showed strong activity (ic50 < 100 `g/ml). the metabolites contained in the crude extract of t. asperellum were the reason for its good bioactivity. studies have revealed that secondary metabolites contained in t. asperellum are tannins, alkaloids, triterpenoids (1.11 mg/ml), phenolics (5.98 mg/ml), and flavonoids (3.76 mg/ml) (ikram et al., 2019; omomowo et al., 2020; sumilat et al., 2022). phenolates are the most dominant secondary metabolites found in t. asperellum. phenolic compounds are able to inhibit bacterial growth and reduce oxidative stress. the hydroxyl group © 2023 the authors. page 172 of 177 oktiansyah et. al. science and technology indonesia, 8 (2023) 170-177 table 1. mic and ic50 values of ethyl acetate extract and pure compounds from the endophytic fungus t. asperellum with tetracycline and ascorbic acid as standards samples mic values (`g/ml) antioxidant activity e.-coli s.-aureus s.-thypi b.-subtilis ic50 (`g/ml) etoac extract 128 128 32 64 12,2**** compound 32 64 32 64 43,88*** tetracycline a 4 4 4 4 ascorbic acid b 10,08**** note: aantibacterial standard; bantioxidant standard; antioxidant activity ic50 (`g/ml): **** very strong < 20`g/ml ***strong < 100 `g/ml; **moderate 100-500 `g/ml;*weak > 500 `g/ml table 2. the nmr data of compound 1 (1h-500 mhz; 13c-125 mhz in cd3od) and 1* (13c-75.5 mhz in dmso-d6) 𝛿c ppm 1 type of c 1 𝛿h ppm ( ∑ h. multiplicity (hz)) 1 hmbc 1 𝛿c ppm 1* 136.3 c 127.5 130.6 ch 8.26 (1h, d, j= 9.0 hz) 130.6; 150.6; 166.3 131.1 123.2 ch 8.30 (1h, d, j= 9.0 hz) 123.2; 136.3; 150.6 114.4 150.6 c 159.9 123.2 ch 8.30 (1h, d, j= 9.0 hz) 123.2; 136.3; 150.6 114.4 130.6 ch 8.26 (1h, d, j= 9.0 hz) 130.6; 150.6; 166.3 131.1 166.3 cooh 169.4 * cho et al. (1998) and long saturated side chain give this compound the ability to thwart the protein and dna synthesis activity of bacteria through inhibition of ribonucleic acid reductase activity, and reduce the surface permeability of bacterial cell walls (adamczak et al., 2019; burel et al., 2021). based on the literature, the constituent of secondary metabolites contained in the extract of endophytic fungi is similar to the host plant. this indicates that endophytic fungi can copy secondary metabolites of their host plants because of their role in mutualistic interactions. 3.3 compound isolation and identification ethyl acetate extract of t. asperellum (2 g) after being preabsorbed with silica gel in a ratio of 1:1, followed by the separation of compounds on column chromatography using silica gel as a stagnant phase. the eluent used was n-hexane:etoac (10:0 → 0:10) to etoac:methanol (10:0 → 0:10) gradient, which obtained five subfractions (f1-f5). based on the staining pattern on tlc, the f3 subfraction was column chromatographic again with n-hexane:etoac (3:7 → 0:10) eluent and gave four subfractions (f3.1-f3.4). subfraction f3.3 was rinsed with n-hexane:etoac (1:1) solvent to obtain compound 1 (31.4 mg). the 1h-nmr spectral (figure 3) of the pure compound 1 showed the presence of two proton signals, namely at 𝛿h 8.26 and 8.30 ppm. both signals have a complicated doublet multiplicity with the integration of two protons. both of these signals are in the chemical shift of the aromatic region and each has an ortho-lot constant ( j = 9 hz) which demonstrates figure 3. the 1h-nmr spectre of compound 1 (1h-500 mhz; in cd3od) that the pure compound is an aromatic compound with para position substitution. this causes two pairs of ortho protons to exist in the same chemical shift. the 13c-nmr spectra (figure 4) of the pure compound 1 exhibited the existence of five carbon signals, all of which were sp2. carbon at 𝛿c 123.2 and 130.6 ppm with large intensity © 2023 the authors. page 173 of 177 oktiansyah et. al. science and technology indonesia, 8 (2023) 170-177 figure 4. the 13c-nmr and hmqc spectra of compound 1 (1h-500 mhz; 13c-125 mhz in cd3od) figure 5. the hmbc spectra of compound 1 (1h-500 mhz; 13c-125 mhz in cd3od) indicate that there are two carbon equal in each of these signals. this is backed by the 1h-nmr spectrum which shows the presence of two equivalent protons. in the spectrum there are carbons in the low field 𝛿c 166.3 and 150.6 ppm which indicate the presence of acid carbonyl carbon and oxyaryl carbon, respectively. the analysis of the proton and carbon nmr spectra was confirmed by the data on the hmqc spectrum listed in table 1, which showed that there were two 1h-13c correlations through one band consisting of two interactions on the aromatic ring. the hmbc spectre (figure 5) demonstrated a correlation of 1h-13c through two or three bonds. the aromatic proton signal at 𝛿h 8.26 ppm is correlated through three bonds with its equivalent aromatic carbon (𝛿c 130.6 ppm); oxyaryl quaternary carbon (𝛿c 150.6 ppm); and carbonyl carbon of the carboxylic acid (𝛿c 166.3 ppm). the aromatic proton at 𝛿h 8.30 ppm is correlated through three bonds with its equal aromatic carbon (𝛿c 123.2 ppm); oxyaryl quaternary carbon (𝛿c 150.6 ppm); and quaternary aromatic carbon (𝛿c 136.3 ppm). the correlation indicates that the carbonyl group of the carboxylic acid is directly attached to the aromatic ring and is para-substituted with the hydroxyl group. the proton hydroxyl signal did not appear on the spectral because the authentic compound was measured with the cd3od solvent. the 1d and 2d nmr spectrum data for compound 1 and the spectrum 13c nmr of 4-hydroxybenzoic acid (1*) from reference cho et al. (1998) were listed in table 2. according to spectral analysis of 1h-nmr, 13c-nmr, figure 6. the placement of the 𝛿c at the 4-hydroxybenzoic acid isolated from endophytic fungi trichoderma asperellum (1) and 4-hydroxybenzoic acid from reference (1*) hmqc, and hmbc, it can be described that compound 1 has a para-substituted benzene ring by a hydroxyl group and a carboxylic acid carbonyl. based on spectrum analysis and after comparing with reference, it was suggested that the chemical structure of compound 1 is 4-hydroxybenzoic acid as shown in figure 6. the compound produced by t. asperellum from sungkai leaves (figure 6) showed strong antibacterial and antioxidant activity (mic ≤ 64 `g/ml; ic50 < 100 `g/ml). studies have found that the hydroxyl group at a particular position on the aromatic ring enhances the antibacterial effect. at least, one hydroxyl group on ring a (especially at c-7) is essential for the antibacterial activity of flavonoids (górniak et al., 2019; sarbu et al., 2019). however, several studies also revealed that a number of hydroxyl groups on two aromatic rings can reduce the antibacterial effect (farhadi et al., 2019; shamsudin et al., 2022). this finding strengthens the hypothesis that the special location of the hydroxyl group likely affects the antibacterial activity. likewise with the antioxidant mechanism due to the presence of aromatic hydroxyl groups. this antioxidant property is closely associated to the chemical structure of the compound, namely the number of hydroxyl groups, the reciprocal area of para in the aromatic ring, and the grade of esterification. studies explain that the removal of hydroxyl groups can reduce coplanarity which can reduce the ability of compounds to stroll free radicals (kubiak tomaszewska et al., 2022; platzer et al., 2022). substitution of the hydroxyl group at its position (c3) with a methyl or glycosyl group can eliminate the antioxidant activity of quercetin (ferraz et al., 2020; mucha et al., 2021). phenolic acids consisting the same number of hydroxyl groups bonded to the aromatic ring do not differ significantly in their antioxidant properties (spiegel et al., 2020) . this indicates that the location of the hydroxyl group significantly affects the antioxidant properties of a compound. © 2023 the authors. page 174 of 177 oktiansyah et. al. science and technology indonesia, 8 (2023) 170-177 in this study, the compound 4-hydroxybenzoic acid has a double band in the hydroxyl group, causing this compound to be active as an antioxidant. 4. conclusion the bioactive compound found from trichoderma asperellum isolated from sungkai leaves was 4-hydroxybenzoic acid. this compound has antioxidant and antibacterial activity in the strong category. based on research, this compound can be used as a new material for drugs with several modifications. 5. acknowledgment the author is grateful to kementerian pendidikan, kebudayaan, riset, dan teknologi for providing financial support through the penelitian dasar unggulan perguruan tinggi, contract number 142/e5/pg.02.00.pt/2022, derivative contract number 0149.01/un9.3.1/pl/2022. references abbas, s., t. shanbhag, and a. kothare (2021). applications of bromelain from pineapple waste towards acne. saudi journal of biological sciences, 28(1); 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168–178 © 2023 the authors. page 177 of 177 introduction experimental section sample preparation and isolation of endophytic fungi characterization and identification of fungal endophytes morphologically molecular identification of fungal endophytes cultivation and extraction antioxidant activity test antibacterial activity test isolation and identification of compound result and discussion isolation and identification of fungal endophytes bioactivity of fungal endophyte compound isolation and identification conclusion acknowledgment author index vol. 3 no.1 january 2018 a adipati napoleon amin ali mubarok annisa amriani aris perdana kusuma arum setiawan d darvi mailisa putri dodi devianto f fikri ardiansyah h hary widjajanti herlina i indah solihah indra yustian l laila hanum m maiyastri mardiyanto maria lusia mirza firdyah astari muharni muhammad faizal muhammad fajar muhammad said n novia nuni gofar nurul kholidah o oktia charmila r risfidian mohadi rizky sintya rupiah s soilia fertilita y yuanita windusari z zaidan p negara zulkifli dahlan title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper coprecipitation synthesis and antimicrobial effect study of europium doped spinel manganese ferrites nanoparticles (mneu0.1fe1.9o4nps) amina chidouh1*, tarek tahraoui2, badra barhouchi3 1laboratory of chemistry, physics and materials biology, department of natural sciences, higher normal school of technological education, skikda, 21000, algeria2mines metallurgy materials laboratory l3m, national higher school of technology and engineering ensti annaba, 23000, algeria3pharmaceutical sciences research center (crsp), constantine, 25000, algeria *corresponding author: amchidouh@gmail.com abstractdue to the high prevalence of micro-organisms resistant to conventional antimicrobials, the search for new antimicrobial drugs isunderway, with nanoparticles being one of the options. this study reports for the first time the use of the coprecipitation method tosynthesize europium (eu) doped spinel manganese ferrites nanoparticles (mneu0.1fe1.9o4nps). the purpose of this research is todetermine the antimicrobial activity of mneu0.1fe1.9o4nps. mneu0.1fe1.9o4nps were analyzed using fourier transform infraredspectroscopy (ftir), x-ray diffraction (xrd), and scanning electron microscopy (sem) combined with energy dispersive x-rayanalysis (edx) to determine their structure, size, morphology and elemental compositions. the antimicrobial activity of synthesizednanoparticles was evaluated qualitatively using a diffusion disc on agar, followed by minimum inhibitory concentrations (mic)determination. the findings show that all tested strains were adversely affected by the examined nps, where e. coli exhibited thehighest sensitivity to nps, followed by s. aureus. the nps displayed a moderate level of anti-candida action. mneu0.1fe1.9o4npscould be exploited in biomedical usages. keywordscoprecipitation method, nanoparticles, antibacterial activity, anti-candida action, ferrites spinel received: 19 january 2023, accepted: 20 june 2023 https://doi.org/10.26554/sti.2023.8.3.494-500 1. introduction antibacterial resistance rapidly increases throughout numerous bacterial species, becoming a significant clinical and public health problem worldwide (kadiyala et al., 2018) . nanoscale engineering of nanoparticles (nps) and surfaces gives new ways for antibacterial drugs that increase conventional organic chemistry methods (bozon-verduraz et al., 2009; jiang et al., 2009). metal oxide nps (mo-nps) have shown promising results in inhibiting bacterial growth and combating antibiotic resistance (djurišić et al., 2015; horie et al., 2012). mo-nps are also desirable as antimicrobial medicaments because they are stable and less toxic to human cells than organic nps (deravi et al., 2007) . their nanoscale and variable surface chemistry. their changeable surface chemistry and nanoscale permit mo-nps to cause toxicity of bacteria over different modes of action, like proteolysis, enzyme inhibition, cell membrane lysis, oxidative stress and lipid peroxidation (djurišić et al., 2015; coker et al., 2012; allahverdiyev et al., 2011). among the various mo-nps, spinel ferrites (mfe2o4 such as m=mn2+, fe2+, co2+, ni2+) have been widely used due to their magnetic and electrical advantages (reddy et al., 2012; kollu et al., 2015). mn is of particular interest in the biomedical field due to its different oxidation states. mn2+ ions show the highest stability compared to mn3+ and mn4+ ions (kalaiselvan et al., 2022) . a cubic spinel structure characterizes manganese ferrite (mnfe2o4). these nanoparticles are necessary materials based on their moderate magnetization, size, biocompatibility, high sensitivity, good chemical stability and tunable toxicity in biological systems (al zahrani et al., 2022; kalaiselvan et al., 2022). these ferrites are highly important in biomedicine as magnetic carriers for bioseparation, protein immobilization and enzymes (arulmurugan et al., 2005; costa et al., 2003). mnfe2o4 nanostructures are promising for clinical cancer diagnosis and therapy (kalaiselvan et al., 2022) . the chemical formula ab2o4 generally represents the spinel structure, where a and b represent the tetrahedral (surrounded by 4 oxygen atoms) and octahedral (surrounded by 6 oxygen atoms) sites (kalaiselvan et al., 2022) . different synthesizing methods, such as hydrothermal synthesis, alcohol dehydration, and sol-gel and spray drying, have https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.494-500&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.494-500 chidouh et. al. science and technology indonesia, 8 (2023) 494-500 been reported (liu et al., 2018; rahman and ahmed, 2005). however, these processes are not economically suitable for large-scale production. the coprecipitation process enables the production of ultrafine powders with chemically uniform composition, orderly size and good reactivity (bueno et al., 2007; verma and chatterjee, 2006). the advantages of this process are ease of processing, excellent production efficiency, low energy loss and high-purity product (bandekar et al., 2019) . the main drawbacks of co-precipitation methods are poor crystallinity and particle size dispersal, large agglomeration, and the need for ph control (houshiar et al., 2014; zahraei et al., 2015). recently, mo-nps synthesized by rare earth (re) ion doping have received considerable attention due to their field of applications (park et al., 2016; prodi et al., 2015; wang, 2008). according to various studies (bouzigues et al., 2011; das and das, 2013; yu et al., 2009; zhuang et al., 2015), rare-earth metals are essential in manufacturing modern technologies such as mobile phones, computers, biomedical applications and solar cells. particular attention has been paid to rare-earth cations, such as eu3+, because of the resonance energy levels and their suited spectroscopic properties. therefore, europium has been investigated for cancer treatment applications and used in dyes for magnetic resonance applications (jahani et al., 2016) . rare earth elements doped manganese ferrite has many biological activities. akhtar et al. (2019) concluded that mn0.5zn0.5smxeuxfe1.8−2xo4 (0.01≤×≤0.05) nps have potential probable anti-cancer and antibacterial abilities activities. mohafez et al. (2021) indicated that an acceptable antifungal effect was observed in the presence of mnce1.4fe0.6o4 nanoparticles. al zahrani et al. (2022) reported that the higher antibacterial activity of ce3+ substituted mnfe2o4ncs was observed. therefore, to our knowledge, there are currently undetailed studies about the synthesis and antimicrobial activity of europium-doped manganese ferrite nanoparticles (mneu0.1fe 1.9o4nps). to this end, this study investigates an original study about the morphological, structural and antimicrobial activity of mneu0.1fe1.9o4nps. the findings that were achieved are thoroughly described. 2. experimental section 2.1 synthesis of europium-doped manganese ferrite nano particles (mneu0.1fe1.9o4nps) the coprecipitation method was used to synthesize nanoparticles of europium-doped manganese ferrite with the composition of mneu0.1fe1.9o4nps. manganese chloride tetrahydrate mncl2.4h2o (biochem, chemopharma), europium chloride eucl3 (sigma-aldrich) and ferric chloride hexahydrate fecl3.6h2o (biochem, chemopharma) were taken in the molar ratio of 1:0.1:1.9 and dissolved in 100 ml of doubledistilled water with constant magnetic stirring for an hour. sodium hydroxide (2m) solution was added drop after drop until the solution’s ph reached around 12. instantaneously, the orange solution turned dark brown. the solution was stirred continuously in a water bath at 80°c. the precipitate was filfigure 1. ftir spectrum of mneu0.1fe1.9o4 nanoparticles tered and repeatedly rinsed with deionized water and acetone, then dehydrated at 80°c in the oven for 2 h. the sample was annealed at 600°c in an electric muffle furnace for 6h (bandekar et al., 2019) . the co-precipitated ferrite was ground using an agate pestle and mortar to obtain fine particles. 2.1.1 mneu0.1fe1.9o4nps characterization fourier transform infrared spectroscopy (ftir) analysis of the synthesized nanoparticles was obtained with a shimadzu ftir-8000 spectrometer at room temperature utilizing kbr pellets in the range of frequency of 4000-400 cm−1 with a wavenumber resolution of 1 cm−1. the morphological and elemental analysis was recorded using scanning electron microscopy (sem-edx quanta 250). x-ray diffraction (xrd) analysis has been recorded utilizing a rigaku x-ray diffractometer with high-intensity cu-k𝛼 radiation (_ = 1.54178 å). 2.2 microorganisms and growth conditions this study utilized five classified bacteria atcc: american type culture collection: gram-positive bacteria: staphylococcus aureus 25923 and enterococcus faecalis 29212, and gramnegative bacteria: escherichia coli 25922, klebsiella pneumoniae 700603 and pseudomonas aeruginosa 25953. one clinical yeast, candida albicans, was also tested. the microorganisms were graciously supplied from the culture collection of the pharmaceutical sciences research center, algeria. nutrient agar was used as the growth media. 2.3 antimicrobial assays the qualitative assessment of the synthesized nanoparticles antimicrobial effect was performed using disk diffusion on agar and minimum inhibitory concentration (mic) (vanden and vlirtinck, 1993) . the microbial strains were pre-grown at © 2023 the authors. page 495 of 500 chidouh et. al. science and technology indonesia, 8 (2023) 494-500 figure 2. sem micrographs with average particle size distribution of mneu0.1fe1.9o4 table 1. elemental composition of mneu0.1fe1.9o4 nanoparticles obtained from edx analysis elements weight% atomic% o k 47.89 77.28 eul 5.08 0.86 mnk 15.48 7.27 fek 31.55 14.59 37.0±0.1°c for 18 h on nutrient agar. each strain was diluted in a saline solution at the mcfarland scale 0.5, 1.5 × 108 ufc/ml (equivalent to do 0.08-0.1/_ = 625 nm). the inoculum was streaked into agar plates using a sterile swab after the mueller hinton agar (mha) had solidified, and the surface of the mha was covered with a sterile filter disc (whatman paper n°3) with a 6-mm diameter. a concentration of 2 mg/ml of nps was prepared in methanol, and 50 `l of the nps was dropped onto the inserted discs. the plates have been kept at 37°c for 18-24 h. methanol was employed as a negative control. gentamicin (gen) and ampicillin (amp) were used as positive controls. the effectiveness was determined by determining the zone’s diameter of microbial growth inhibition (zoi) atop the disc and recording the diameter with a transparent ruler in millimeters. all tests were performed in triplicate. figure 3. edx spectra and elemental composition for mneu0.1fe1.9o4 nanoparticles figure 4. xrd pattern of mneu0.1fe1.9o4 nanoparticles mic experiment was done in the 96-microplate using the broth dilution method. 100 `l volume of the obtained nanoparticle at different concentrations (16 to 0.5 mg/ml) was prepared in wells previously inoculated with 50 `l of mueller hinton broth (mhb) broth medium. the freshly adjusted inoculum to do of 0.08 to 0.1 (50 `l) was added to the prepared nps solution and then incubated for 24 hours at 37°c. untreated bacteria with dmso was used in the trial as the negative control. the lowest concentration of the tested compound that the microorganism does not demonstrate visible growth was defined as the minimum inhibitory concentration (mic) (rehman et al., 2019) . 3. results and discussion ftir spectroscopy is a valuable technique for structural analysis and cations redistribution between tetrahedral and octahedral sites in spinel structures (hakeem et al., 2016) . figure 1 shows the ftir spectrum of mneu0.1fe1.9o4nps. the band at 1425 cm−1 is for out-of-plane deformation vibration of the c-h. a band characterizes adsorbed water at 3435 cm−1. the © 2023 the authors. page 496 of 500 chidouh et. al. science and technology indonesia, 8 (2023) 494-500 bands at 2131 cm−1 and 1630 cm−1 are attributed to o-h stretching and h-o-h bonded vibration modes, respectively. the existence of the 576 cm−1 band is based on the vibration stretching of octahedral and tetrahedral groups (hakeem et al., 2016) . figure 2 shows the scanning electron microscopy (sem) micrographs of mneu0.1fe1.9o4 nps. micrographs were taken at scales of 5, 10, 20 and 50 µm, it demontrates the formation with uniform distribution of agglomerated nanoparticles (devi and soibam, 2018) . due to their high surface energy and magnetic properties, nanoparticles have the potential to aggregate and develop into large assemblages (sagadevan et al., 2018) . the average nanoparticles size distribution was estimated in the range of (30 nm-70 nm) using imagej software . figure 3 displays the results of edx measurments for the elemental composition of the prepared sample. edx spectra show the purity, homogeneity and presence of eu in the sample, indicating that eu was successfully doped into the spinel structure. as determined by the edx analyses, the elemental composition is listed in table 1 with the atomic and weight percentages. x-ray diffraction measurements show that peaks of mneu0.1 fe1.9o4nps correspond to peaks of a typical spinel structure prepared by coprecipitation. figure 4 displays the prepared nanoparticles x-ray diffraction pattern. the crystallite’s average size was in the range of 40.9 nm. intense diffraction peaks occur at 2\=18.15°, 29.78°, 34.99°, 42.63°, 52.70°, 56.18°, 61.73°, 64.68° corresponds to (111), (220), (311), (400), (422), (511), (440), (531) usual planes of ferrite spinel arrangements fe2mno4 that is characterized by face-centered cubic phase belonging to space group of fd3m (hakeem et al., 2016; mohafez et al., 2021) according to the standard card jcpds file no. 100319 (wang, 2008) . it is observed at about (20.24°, 33.25° and 40.90°) and (24.22°, 33.25°, 35.68°, 49.57° and 54.26°) the appearance of secondary phase peaks with an insignificant amount which corresponds to the ortho ferrite (eufeo3) (01-074-1475) and hematite (fe2o3) (01-089-0599) phases respectively (zubair et al., 2017) . one of the crucial causes in the development of secondary phases is attributed to the low solubility and electronic configuration of the rare earth element eu3+ (mohafez et al., 2021; shirsath et al., 2014). the eu3+ ion with a bigger radius of about (1.07 å) prefers to occupy the octahedral sites of fe3+, whose ionic radius is 0.67 å. consequently, when the eu3+ ions substitution is high, this directs to the creation of secondary phases as an impurity on the grain boundaries due to the diffusion of re-eu3+ ions (zubair et al., 2017) . the sample’s average value of the peaks of xrd analysis is used to determine the crystallite size (d). the value of ‘d’ is calculated using scherrer’s formula cullity (1978) as follows: d = k𝛽 cos\ (1) in which ‘d’ signifies the average crystallite size in nm, the shape factor, ‘k’, has a value of 0.94, x-rays are employed, and their wavelength is _ , \ is the bragg’s diffraction angle, and 𝛽 is fwhm (zubair et al., 2017) . to the best of our knowledge, the antimicrobial action of mneu0.1fe1.9o4nps was investigated for the first time on both yeast and gram-positive/negative bacteria. subsequently, the results indicate that the synthesized mneu0.1fe1.9o4nps had exceptional antimicrobial activity against selected microbial strains as shown in table 2. moreover, the checked nps were harmful to all the tested strains at the dose of 2 mg/ml and gave moderate to strong activity, which indicated by the formation of a clear zone. the inhibition zones (zoi) were ranged from 12 to 24 mm. among the tested bacterial strains, e. coli exhibited the strongest sensitivity to nps, followed by s. aureus, with zoi values of 24 ± 0.14 mm and 21 ± 0.24 mm, respectively. furthermore, the produced nps also displayed an equally positive effect against e. faecalis, k. pneumoniae and p. aeruginosa. xiu et al. (2012) included that inorganic nanoparticles are distinguished for their large surface-to-volume ratios and nanoscale sizes, enhancing their response to pathogenic bacteria. according to jesudoss et al. (2016) , the ferrite nanoparticles involved significantly in combating infectious against both grampositive and gram-negative bacteria. in addition, candida albicans remains a potent yeast strain, where the nps showed a moderate anti-candida activity and presented the weakest inhibition zone (zoi: 12 ± 0.24 mm). the encouraging antibacterial potential of mneu0.1fe1.9o4nps nanoparticles was corroborated by the results of experiments and compared with antibiotics, gentamicin and ampicillin, as a positive control. contrary to gentamicin which displayed a remarkable antibacterial activity, ampicillin had no effect against all tested bacteria. as revealed in table 2, the mic (minimum inhibitory concentration) of mneu0.1fe1.9o4nps was found to be 1 mg/ml for e. coli, k. pneumoniae, p. aeruginosa and c. albicans whereas 2 mg/ml mic value was recorded for s. aureus and e. faecalis. in agreement with our results, the synthesized europium doped cerium dioxide (eu3+ceo2) nanoparticles exhibited outstanding antibacterial effectiveness against e. coli and s. aureus with the following diameter of inhibition zone (zoi): 37 ± 0.3 mm and 18 ± 0.2 mm, respectively (gnanam et al., 2021) . ashour et al. (2018) demonstrated that the ferrites had antibacterial activity against all pathogens tested. zinc cobalt ferrite nanoparticles (zcfo) were the most effective, with zones of inhibition of 13.0 mm against bacillus subtilis and staphylococcus aureus. however, akhtar et al. (2019) demonstrated an improved activity against e. coli compared with s. aureus of mn0.5zn0.5sm xeuxfe1.8−2xo4nps. in contrast, mohafez et al. (2021) concluded that mnfe2o4 and mnce1.4fe0.6o4np s did not show antibacterial activity against infectious gram-negative bacteria: (escherichia coli, acinetobacter baumannii and pseudomonas aeruginosa), as well as infectious gram-positive bacteria: (bacillus cereus, staphylococcus epidermidis and streptococcus pneumoniae) even at concentrations of 1024 `g ml−1. according to © 2023 the authors. page 497 of 500 chidouh et. al. science and technology indonesia, 8 (2023) 494-500 table 2. antimicrobial activity of mneu0.1fe1.9o4nps tested against various microorganisms microbial strains reference number zone of inhibition zoi (mm) mic (atcc) mneufe2o4 gentamicina ampicillina methanolb (mg/ml) e. coli 25922 24± 0.14 20± 0.23 1 s. aureus 25923 21± 0.24 23± 0.29 2 k. pneumoniae 700603 15± 0.32 11± 0.30 1 p. aeruginosa 25953 15± 0.15 15± 0.12 1 e. faecalis 29212 15± 0.33 20± 0.29 2 c. albicans clinical 12± 0.24 / / 1 atcc: american type culture collection (a): positive control (antibiotics: gentamicin gen and ampicillin amp), (b): negative control (methanol), (-): no effect.mic: minimum inhibitory concentration of the tested nps. the results were expressed as mean ± standard deviation. gheidari et al. (2020) , pseudomonas aeruginosa and staphylococcus aureus were the most resistant bacteria against cofe2o4 nanoparticles. mnfe2o4 and mnce1.4fe0.6o4 nanoparticles were also tested against pathogenic fungi aspergillus fumigatus, candida albicans and fusarium oxysporum. as a result, adequate antifungal activities were detected in the presence of mnce1.4fe0.6o4 nanoparticles (mohafez et al., 2021) . al zahrani et al. (2022) showed that the increasing concentrations of mnfe2o4 and ce-doped mnfe2o4 nanocrystallites (ncs) eventually stop the replication operation and cease the spread of gram-negative/po sitive bacterium when the mnce0.3fe1.7o4ncs had higher activity than the other doped and undoped samples. meanwhile, the bacterial status and inoculum size influenced the effectiveness of antimicrobials as well as their applied concentrations (li et al., 2017) . however, our findings showed that our mneu0.1fe1.9o4nps has a better antibacterial effect against gram-negative bacteria. it could be because this class of bacteria has less rigid cell walls than gram-positive bacteria, which have a more complicated outer membrane (jiang et al., 2020) . generally, their cell wall is thicker due to the peptidoglycan layer absent in gram-negative bacteria. this layer hinders the penetration of metal ions into the cytoplasm, whereas in gram-negative bacteria, the nps easily penetrate the cell membrane and cause damage (slavin et al., 2017) . the improved antibacterial action might be associated with the exposure of ions that have positive charges, like as eu3+, fe3+ and mn2+, which charge the bacteria membrane and affect membrane wholeness, therefore, can decrease electrostatic interaction, allowing membrane obstacles to be traversed, which disturbs the respiratory chain that kills cells. cell death is brought on by breaching membrane barriers, which messes up the electron transport chain (al zahrani et al., 2022) . thus, the reported antimicrobial property of mneu0.1fe1.9o4nps in this research will open up a new way to apply these nanoparticles as a new source of antimicrobials, which can be further explored in the biomedical sector. 4. conclusion spinel europium-doped manganese ferrite nanoparticles (mne u0.1fe1.9o4nps) were synthesized using coprecipitation meth od. by using xrd analysis, the sample’s spinel cubic structure was determined. the crystallite’s average size was in the range of 40.9 nm. edx spectra of the sample confirm the successful doping of eu into the spinel structure. the antimicrobial action of mneu0.1fe1.9o4nps was investigated on both yeast and gram-positive/negative bacteria. the present study showed that the synthesized mneu0.1fe1.9o4nps had exceptional antimicrobial activity against selected microbial strains and can be used in biomedical applications. 5. acknowledgment we are grateful to professor djekoun abdelhamid, the director of pharmaceutical sciences research center (crsp), algeria for his support. we respectfully acknowledge the contribution made to this research by dr. boukhzar skander, research fellow at the research center in industrial technologies (crti), algeria. references akhtar, s., s. rehman, m. a. almessiere, f. a. khan, y. slimani, and a. baykal (2019). synthesis of mn0.5zn0.5smxeuxfe1.8−2xo4 nanoparticles via the hydrothermal approach induced anti-cancer and antibacterial activities. nanomaterials, 9(11); 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current opinion in biotechnology, 33; 327–335 zubair, a., z. ahmad, a. mahmood, w. c. cheong, i. ali, m. a. khan, a. h. chughtai, and m. n. ashiq (2017). structural, morphological and magnetic properties of eu doped cofe2o4 nano-ferrites. results in physics, 7; 3203–3208 © 2023 the authors. page 500 of 500 introduction experimental section synthesis of europium-doped manganese ferrite nanoparticles (mneu0.1fe1.9o4nps) mneu0.1fe1.9o4nps characterization microorganisms and growth conditions antimicrobial assays results and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper photoprotective and antioxidant potential of indonesia’s klanceng honey beehive waste yuliana purwaningsih1*, ahmad fuad masduqi2, erwin indriyanti1, mighfar syukur1 1bachelor program of pharmacy, semarang pharmaceutical college, semarang, 50192, indonesia2vocational program of pharmacy, semarang pharmaceutical college, semarang, 50192, indonesia *corresponding author: y14purwaningsih@gmail.com abstracta byproduct of the honey processing called klanceng honey beehive waste is said to still contain secondary metabolites that arebeneficial to health. the objective of this research was to assess the photoprotective properties of an ethanol extract, n-hexanefraction, and ethyl acetate fraction obtained from the waste of an indonesian klanceng honey beehive that originated in magelang.the dpph free radical technique was applied to quantify antioxidant properties, and the mansur equation’s spf value was used tocalculate photoprotective activity. the analysis of the data revealed that the ic50 values for the ethanol extract, n-hexane fraction,and ethyl acetate fraction were, respectively, 470.2935±0.9249, 207.1869± 2.6510, and 216.4892±0.8349. the ethanol extract,n-hexane fraction, and ethyl acetate fraction of the samples had spf values of 3.872, 3.529, and 9.358, respectively. the ethylacetate fraction, as opposed to the ethanol extract and the n-hexane fraction, has greater potential as a photoprotective agent as aresult. keywordsantioxidant, extract, fraction, honey beehive, photoprotective received: 9 oktober 2022, accepted: 28 december 2022 https://doi.org/10.26554/sti.2023.8.1.137-143 1. introduction the human skin serves as a protective border between the internal and exterior environments, guarding against radiation, toxic substances, mechanical trauma, and microbial invasion. it has been abundantly obvious in recent years that the skin plays a significant role in the immune system. environmental factors like ultraviolet (uv) radiation, oxidative sterss, hazardous and allergic substances, and mechanical damage, as well as intrinsic factors like genetic propensity, immunological and hormonal prestige, and stress, have an impact on the condition and function of the skin. the consequent abnormalities in the skin result in photoaging, inflammation, decreased immune responses, an imbalance of epidermal homeostasis, and other skin problems (fernandez garcia, 2014) . photo-oxidative reactions caused by uv radiation exposure cause biomolecular damage, affecting the authenticity of skin cells and causing skin problems. damage to these photooxidative contributes to the pathological process and is responsible for the oncet of many skin disorders. continuous sun exposure and other environmental factors can result in the induction of oxidative stress, which has a high reactivity with genetic material, peptides, and fatty acids and frequently causes antioxidant significant damage (vijayakumar et al., 2020) . photoprotective agents shield the skin from the damage consequences of ultraviolet natural daylight (latha et al., 2013) . plant-derived phytochemical compounds have the potential to prevent molecular damage by capturing and attempting to destroy ros raised by biological mechanisms, smog, inhaling, and medicines. polyphenols are the most important natural product class in dermatology due to their absorption spectrum, which efficiently filters uv radiation, reducing the possibility of radiation penetrating deep into the skin layer (vijayakumar et al., 2020) . bee products are regarded as a source of natural antioxidant potential proficient in combating the effects of oxidative stress, which underlies the pathogenesis of several diseases (kocot et al., 2018) . beehive also contains various phenolic and flavonoid compounds that can be used as antioxidants (pérez-pérez et al., 2013) . beehives provide protection for bee colonies from microbial species, mushrooms, infectious agents, and carnivores, as well as a location for honey production, bee pollen, and bee growth and development. the condition of beehives has a significant bearing on the quality of honey (pérez-pérez et al., 2013) . the content of compounds in https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.137-143&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.137-143 purwaningsih et. al. science and technology indonesia, 8 (2023) 137-143 honey beehives serves as a protector and determinant of honey quality, including flavonoids, which are natural phenol compounds, and beeswax. the trigona bee group is a non-rigid bee group that lives socially in a colony that usually tries to live in trunks, wood, bamboo, and soil. one bee colony has only one queen, hundreds of male bees, and thousands of worker bees; one species of trigona sp. is t. itama, which produces more raw propolis (hrncir et al., 2016) . the content of propolis in the beehive has many benefits, such as drugs and cosmetics (wagh, 2013) . honey is a sticky substance made by stingless bees. honey is well-known throughout the world for its excellent nutritional constituents that are advantageous to human health, and propolis is commonly referred to as "bee glue," which is a collective term for the resinous substance gathered by bees from diverse types of plants (puspawati et al., 2019) . in muntilan district, magelang, indonesia, many klanceng honey bees, or trigona sp., are cultivated. according to local honey breeders, taking klanceng honey is extorting honey from the hive, which gives honey and waste. it is estimated that honey beehive waste still contains phytochemicals that can be used to improve one’s health. the content of compounds in beehives functions as protectors and determinants of honey quality, including phenolic compounds and flavonoids. honey has lower antioxidant activity than propolis, which is due to the variety of phenolic compounds present in the extract (mouhoubi tafinine et al., 2016) . notably, regardless of its composition, propolis extract always contains protective effects. in both animal and cell culture studies, aqueous extracts of propolis have been shown to possess antioxidant capacity (kocot et al., 2018) . several studies have stated that propolis contains bioflavonoids (sabir, 2005) . the phytochemical content of lisotrigona caciae propolis extract shows the presence of several compounds of flavonoids, xanthones, alkyl resorcinol, triterpenes, other phenol compounds, fatty acids, esters, and sugar (georgieva et al., 2019) . phenolic compounds and flavonoids have antioxidant activity sukweenadhi et al. (2020), antibacterial activity yuan et al. (2021) , and anti-inflammatory activity candiracci et al. (2012) , so it is thought that waste from a honey beehive in muntilan, magelang, may have these properties. based on this description, the purpose of the research is to assess the photoprotective and antioxidant potential of an ethanol extract, n-hexane fraction, and ethyl acetate from honey beehive waste (trigona sp.) that originated in magelang, indonesia. 2. experimental section 2.1 materials the substances used in this study were 96% ethanol (brataco), ethanol p.a. (merck), shinoda reagent (merck), fecl3 (merck), n-hexane (brataco), ethyl acetate (merck), hcl 2n, mayer reagent (merck), bourchard reagent (merck), dragendroff reagent (merck), na2co3 (merck), folin-ciocalteu (merck), gallic acid (sigma), quercetin (sigma), dpph (sigma), ascorbic acid (merck), anhydride acetate (merck), na acetate (merck). the tools used in this study were a set of glass devices commonly used in laboratories, bransonic brand ultrasonic batch, uv-vis shimadzhu 1840 spectrophotometer, a vacuum evaporator, ir-atr agilent 630 spectrophotometer. 2.2 methods 2.2.1 sample the sample used was the waste of honey beehive trigona sp. from muntilan district, magelang regency, central java province, indonesia. samples were sorted to separate rotten materials and impurities. the sample was reduced in size using a knife. 2.2.2 extraction and fractination a total of 100 g of samples were macerated in the sonicator for 1 hour with 96% ethanol and allowed to stand for 24 hours with a sample and solvent ratio of 1:10. the extract was filtered and separated into filtrates and residues. the residue was remacerated in the same manner. maceration was performed three times. in a vacuum evaporator set to 50°c, the filtrate was evaporated until a thick extract was obtained. ten grams of thick extract were fractinated in hexane, ethyl acetate, and ethanol. using an evaporator, the fractionation results were evaporated to obtain a concentrated n-hexane fraction, an ethyl acetate fraction, and an ethanol extract. 2.2.3 phytochemical screening the chemical content of the sample was confirmed using color reagents. flavonoid, tannin, saponin, and terpenoid tests were all performed. a shinoda reaction was used for the flavonoid test, which included extract and filtate plus hcl 2 n, magnesium powder, and amyl alcohol. if the amyl alcohol layer is red, the flavonoid sample is positive (nurhasnawati et al., 2019) . the tannin test was performed with a fecl3 solution that yielded a positive blackish-green color. the alkaloid test was performed using three methods: the dragendroff reagent, the mayer, and the bouchard tests (nurhasnawati et al., 2019) . the saponin test was performed by first adding distilled water to the sample and managing it, then adding hcl 2 n and shaking it to determine the presence of stable foam-positive saponin (nurhasnawati et al., 2019) . the terpenoid test was performed by dissolving a number of samples in ether, which was then evaporated and anhydride acetic acid added. the existence of terpenoids was indicated by the presence of a red or green color in this test (nurhasnawati et al., 2019) . an atr-ftir spectrophotometer was used to identify the functional groups of ethanol extract, n-hexane fractions, and ethyl acetate fractions. the sample was placed on the prism, and the % transmittance on the wave number 4000-400 cm−1 was measured (liu et al., 2006) . 2.2.4 total phenolic content (tpc) using visible spectrophotometry this method based on mathur and vijayvergia (2017) with little modification. the tpc test was performed by pipetting a 1 ml sample (500 – 900 mg/l) solution and 4 ml of folinciocalteu (f-c) reagent. this mixture was kept for 4 minutes © 2023 the authors. page 138 of 143 purwaningsih et. al. science and technology indonesia, 8 (2023) 137-143 before adding 0.4 ml of 7% na2co3 solution and incubating for 120 minutes with distilled water up to 10 ml.. the mixture is measured at its maximum wavelength of 775 nm. the standard solution used was gallic acid with a concentration of 60–100 mg/l in the 10 range. 2.2.5 total flavonoid content (tfc) using a visible spectrophotometry this test was carried out by the colorimetric method using alcl3 based on tristantini and amalia (2019) with modification. as many as 1 ml of samples plus 0.1 ml of 10% alcl3 solution and 0.1 ml of 1 m sodium acetate solution was adhered with aquadest to a volume of up to 10 ml and incubated for 30 minutes. the mixture is measured at a maximum wavelength of 436.5 nm. 2.2.6 antioxidantactivitytestusingdpph(2,2-diphenyl1-picrylhydrazyl) with minor modifications, this antioxidant test method is based on sukweenadhi et al. (2020) . allowing 3 ml of dpph solution 0.4 mm plus 1 ml of samples to stand for 30 minutes. the wavelength of the solution was 517 nm. ascorbic acid was used as a positive control, and dpph in ethanol was used as a blank. using equation 1, the absorbance obtained from the instrument was used to calculate the percentage inhibition(syarifah et al., 2021) . %inhibition = ablank-asample ablank (1) 2.2.7 spf test using uv spectrophotometry the spf value is calculated using a modified method based on sabir (2005) . uv spectrophotometry is used to measure absorbance at 290-320 nm in the 5 nm range for samples with concentrations ranging from 100 to 500 ppm (in ethanol solvents). the absorbance is calculated using the mansur equation (2) to yield the spf value. spf = cf × 320∑︁ 290 ee(_) × i × a(_) (2) where, cf = correction factor (10), ee (_ ) = erythmogenic effect of radiation with wavelength _ , abs (_ ) = spectrophotometric absorbance values at wavelength _ . table 1 shows the values of the ee (_ ) x i constants (khan, 2018) . 3. result and discussion remaceration is used to extract klanceng honey beehive waste for 1 hour at room temperature, aided by ultrasonic waves. in secondary metabolite extraction, the sonification method is an ecofriendly extraction method that is used to remedy the flaws of the maceration method. sonication methods can be completed in much less than an hour, and the impact of damage throughout the phase is negligible or can be lessened (puspawati et al., 2019) . ultrasonic radiation with a frequency greater than 20 khz makes it easier to extract compounds both natural ingredient and inorganic from porous support utilizing liquid solvents. the sound wave of sonicator creates cavity bubbles close the sample tissue, which disintegrate cell walls and release cell contents, including secondary metabolites (khoddami et al., 2013) . the use of an ultrasonic wave to aid extraction rises compound solubility in the solvent, resulting in a reduction in the volume of solvent required (alara et al., 2021) . the maceration results are evaporated in a vacuum rotary evaporator to produce a concentrated brown color extract with a honey aroma, yielding a 36.09 ± 1.69% yield. the use of a vacuum evaporator can lower the temperature of the solvent because the pressure in the flasks decreases, making the solvent more volatile. concentrated extracts are fractionated using n-hexane solvents to obtain nonpolar fractions; the residues are then fractionated with ethyl acetate solvents to obtain semipolar fractions. water fractions are ethyl acetate fractionation residues. each fraction is evaporator to obtain a thick fraction of each fraction of the n-hexane fraction; the ethyl acetate fraction and the water fraction are 49.52 ±8.58%, 37.54 ±3.40%, and 2.15 ± 0.26%, respectively. the secondary metabolite content of the sample was ascertained using phytochemical screening (gurning et al., 2021) . phytochemical analysis reveals that alkaloid compounds, flavonoids, tannins, and terpenoids are present in ethanol extract, n-hexane fractions, and ethyl acetate fractions (table 2). the ftir spectrophotometer results of the ethanol extract, n-hexane fraction, and the ethyl acetate fraction show the same spectrum pattern (figure 1). the three samples have the same spectrum pattern based on the ir spectrum results. the n-hexane fraction exhibits a lower -oh absorption at wave number 3300 cm−1 than the ethanol extract and ethyl acetate fraction. the presence of -oh functional groups in a sample identifies the existence of phenol or alcohol groups (revathi and rigley, 2019) . the aliphatic chalkyl group in the sample was demonstrated by wave number 2800-2900 cm−1. the availability of -c=caromatic groups was indicated by the wave number 1700 cm−1, while the presence of carbonyl groups c=o was noted by the wave number 1350-1500 cm−1. the absorption of the c-oh group from alcohol was implied by the wave number at 1025 cm−1 (stuart, 2004) . according to this analysis, the samples contained polyphenolic compounds. plants produce polyphenols in reaction to external and physiological pressures including pathogenic and insect attacks, uv exposure, and wounds (khoddami et al., 2013) . the basic structure of polyphenols is the benzene ring with hydroxy groups. the phenolic level of the sample is determined by measuring the absorbance at a wavelength of 775 nm using the folin-ciocalteu method. the standard used is 60-100 ppm galic acid with a 10 ppm range. the galic acid standard linear regression equation is y = 0.0082x 0.231, r2 = 0.9970. the total amount of phenolic is given in milligrams of galic acid © 2023 the authors. page 139 of 143 purwaningsih et. al. science and technology indonesia, 8 (2023) 137-143 table 1. the result of phytochemical screening compound group etanol extract ethyl acetate fraction n-hexane fraction alkaloids + + + flavonoids + + + saponin tannin + + + terpenoid + + + figure 1. atr-ftir spectrum of sample figure 2. total phenolic content of sample per 100 g of sample. galic acid is used as a standard because its availability and stability (wabaidur et al., 2020) according to figure 2 and table 3, the total phenolic content of the ethanol extract, as well as the n-hexane and ethyl acetate fractions, increases with increasing sample concentration. this image shows that the ethyl acetate fraction has a higher total phenolic level than the ethanol extract and the n-hexane fraction. the total flavonoid content (figure 3) was defined utilising visible spectrophotometry and alcl3 as a reagent. the construction of a complex among alcl3 compounds and quercetin compounds is the essence of calculating amount of flavonoid using colorimetry method (meilawati et al., 2021) . the total figure 3. total flavonoids contents of sample quantity of flavonoid was described in milligram equivalent of quercetin/100 g sample. measurement of quercetin resulted in a linear regression equation y=0.0072x+0.0038, r=0.9998. the antioxidant activity of the ethanol extract, the n-hexane fraction, and the ethyl acetate fraction was tested using the dpph radical. this method was chosen because dpph is a stable free radical so it is easy to do. this test was executed by visible spectrophotometry at a wavelength of 517 nm with an operating time of 30 minutes (gurning et al., 2021; sembiring et al., 2018). the decrease in dpph concentration was proportional to the increase in antioxidant concentration. ic50 is the effective concentration that induces a 50% reduction in the previous dpph concentration (molole et al., 2022) . the ic50 value for the ascorbic acid standard used in this study was 8.875 ppm, indicating very strong antioxidant activity. ascorbic acid easily and frequently catches superoxide anion species such as superoxide and hydroperoxyl radicals, oxidants, ozone, peroxynitrite, nitrogen dioxide, nitrous oxide radicals, and hypochlorous acid, thereby preventing oxidative stress to other substrates (birangane et al., 2011) . the sunscreen activity of the sample was carried out by uv spectrophotometry. this measurement is made at a wavelength of 290–320 nm. the spf value is estimated based on the mansur equation. table 3 and figure 5 illustrate that the greater the sample concentration, the higher the spf value. the spf value of the ethyl acetate fraction is greater than that of the extract and greater than that of the n-hexane fraction. the © 2023 the authors. page 140 of 143 purwaningsih et. al. science and technology indonesia, 8 (2023) 137-143 table 2. total phenolic content (tfc) of sample concentration (mg/l) ethanol extract ethyl acetate fraction n-hexane fraction 500 0.6227±0.0004 0.7685±0.0014 0.5683±0.0000 600 0.6641±0.0006 0.8307±0.0004 0.5723±0.0022 700 0.7640±0.0006 0.9803±0.0005 0.6466±0.0013 800 0.8788±0.0012 1.0877±0.0007 0.8109±0.0007 900 0.9042±0.0007 1.2389±0.0015 0.8304±0.0006 table 3. spf value of sample concentration of extract protection n-hexane fraction protection ethyl acetate fraction protection sample (ppm) spf value category spf value category spf value category 100 1.424 low 1.991 low 5.010 low 200 1.870 low 2.466 low 6.535 low 300 2.700 low 3.389 low 6.898 low 400 3.872 low 3.529 low 9.358 low 500 5.832 low 4.464 low 11.898 low figure 4. antioxidants test of the sample using dpph concentration of 500 ppm of the extract, n-hexane fraction, and ethyl acetate fraction was able to provide low protection against uv b rays, but in this concentration, ethyl acetate had a higher spf value than the extract and n-hexane fraction. according to geoffrey et al. (2019), protection from uv rays is graded based on the spf value: low (spf 2-15), medium (spf 15-30), high (spf 30-50), and highest (spf>50). honey and propolis contain active compounds involve polyphenol, flavonoids, carotenoids, and avitamin c (mouhoubi tafinine et al., 2016) . as a result, it can be assumed that reusing this honey beehive waste reduces the total phenolic and flavonoid content, thereby affecting its spf activity. 4. conclusion the honey beehive trigona sp. from muntilan district has weak or inactive antioxidant activity and a low spf value, and thus has no development potential. figure 5. spf value of sample 5. acknowledgment the author thanks the lppm pharmaceutical college of semarang for giving the financial support required to complete to complete this study effectively. references alara, o. r., n. h. abdurahman, and c. i. ukaegbu (2021). extraction of phenolic compounds: a review. current research in food science, 4; 200–214 birangane, r., d. chole, and k. s. p. reddy (2011). a review of antioxidants. journal of indian academy of oral medicine and radiology, 23(5); 351 candiracci, m., e. piatti, m. dominguez barragan, d. garcia antras, b. morgado, d. ruano, j. f. gutierrez, j. parrado, and a. castano (2012). anti-inflammatory activity of a honey flavonoid extract on lipopolysaccharide-activated © 2023 the authors. page 141 of 143 purwaningsih et. al. science and technology indonesia, 8 (2023) 137-143 n13 microglial cells. journal of agricultural and food chemistry, 60(50); 12304–12311 fernandez garcia, e. 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(2013). propolis: a wonder bees product and its pharmacological potentials. advances in pharmacological sciences, 2013; 1–13 yuan, g., y. guan, h. yi, s. lai, y. sun, and s. cao (2021). antibacterial activity and mechanism of plant flavonoids to gram-positive bacteria predicted from their lipophilicities. scientific reports, 11(1); 1–15 © 2023 the authors. page 143 of 143 introduction experimental section materials methods sample extraction and fractination phytochemical screening total phenolic content (tpc) using visible spectrophotometry total flavonoid content (tfc) using a visible spectrophotometry antioxidant activity test using dpph (2,2diphenyl-1-picrylhydrazyl) spf test using uv spectrophotometry result and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 2, april 2023 research paper characterization of synthesized nico2o4 with trisodium citrate for supercapacitor material: a preliminary study andriono manalu1*, istas pratomo manalu2, muktar bahruddin panjaitan1, ady frenly simanullang1, parlindungan sitorus3 1department of physics education, faculty of teacher training and education, universitas hkbp nommensen pematangsiantar, pematangsiantar, 21132, indonesia2department of computer engineering, vocational faculty, del institute of technology, toba, 22381, indonesia3department of physics education, faculty of teacher training and education, universitas hkbp nommensen, medan, 20155, indonesia *corresponding author: andriono.manalu@uhnp.ac.id abstractsupercapacitors can be called electrostatic double-layer capacitors (edlcs) or pseudo-capacitors based on their energy storagemechanism. pseudo-capacitors with metal oxide electrodes that transmit electric charge offer great application power but lowstability. this study aims to characterize trisodium citrate (tsc) modified nico2o4/rgo electrodes as a preliminary study for thenico2o4 nanoparticle pseudo-capacitor. the materials were characterized using sem (scanning electron microscopy), xrd (x-raydiffractometer), ft-raman (fourier transform raman spectroscopy), and ftir (fourier transform infrared spectroscopy). all ofthese analyses confirmed that nico2o4 was manufactured successfully using tsc. at xrd, the angles of 2\, namely 45.04 and53.34°, matched the plane of the cubic phase nanorod crystals of nico2o4 with values of 400 and 511, respectively. in the ramanexamination, the presence of rgo, which increased the crystallinity of nico2o4 nanoparticles, was confirmed. ftir analysis indicatedthat the 1550-1600 cm−1 corresponds to a c=c functional group in an aromatic ring or a c=o 𝜋-𝜋 structure, and the wavenumber of2300 cm−1 corresponds to the oh group in tsc, an alkanoate derivative. sem analysis determined that nico2o4 nanoparticles with1 mmol tsc are the ideal material for supercapacitor electrodes, as the structure is the most uniform, soft, and tidy. further analysisis needed to confirm the stability of the modified material. keywordsnico2o4, rgo, trisodium citrate, supercapacitor, pseudo-capacitor received: 9 december 2022, accepted: 5 march 2023 https://doi.org/10.26554/sti.2023.8.2.245-251 1. introduction in this modern age, the advancement of knowledge in technology has a significant impact on human existence. the increasing population and a more wasteful lifestyle have led to an increase in energy demand. to satisfy this demand, enormous quantities of fuel must be supplied at a premium price. due to insufficient storage technology, a significant amount of generated energy is wasted. current energy storage methods are prohibitively expensive or environmentally hazardous in numerous ways (mehta et al., 2020) . therefore, more research and development efforts are required to identify renewable energy sources that are efficient, cost-effective, and environmentally friendly (bhat et al., 2023) . one is the invention of a device for storing and utilizing energy. several advancements in energy storage and conversion technology, such as solar cells, fuel cells, compressed hydrogen, supercapacitors, and batteries, have been made over the past two decades to use sustainable energy storage and conversion systems professionally (ren and huang, 2022) . based on their environmental and economic benefits, the device components (electrodes and electrolytes) should ideally be accessible in a straightforward, economical, and environmentally friendly manner with the appropriate final characteristics (mehta et al., 2020) . the primary requirement for electrical energy derived from renewable resources is an efficient energy storage system (ess). batteries and supercapacitors are the most in-demand forms of energy storage in the current digital era (zheng et al., 2023) . a supercapacitor or electrochemical capacitor is an electric double layer that serves as an energy storage device based on the charging and discharging of the dielectric interface electrode (wang et al., 2015) . supercapacitors offer a high-power density, the capacity to charge quickly, store 10–100 times more energy than batteries, and long service life (>100,000 cycles) (simon and gogotsi, 2020) . based on their energy storage technique, supercapacitors can be called electrostatic double-layer capacitors (edlcs) or pseudo-capacitors (winter and brodd, 2004) . edlc capacitors are typically https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.245-251&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.245-251 manalu et. al. science and technology indonesia, 8 (2023) 245-251 utilized in low-power applications (karthikeyan et al., 2021) , using activated carbon electrodes that have a wide surface area to store electric charges at the electrode/electrolyte interface, such as carbon fiber, carbon aerogel, graphene, and carbon nanotubes (jiang et al., 2018) . the capacitor’s power density and stability are excellent, but its specific capacitance is poor (faraji and ani, 2015) . with metal oxide electrodes whose electric charge transfer is based on reversible faradaic processes (najib and erdem, 2019) , including redox processes on metal oxides, reversible adsorption, and reversible electrochemical doping on conductive polymers for electrodes, pseudo capacitors have a high application power (abdah et al., 2020) . these capacitors generally have a greater energy density and specific capacitance than edlcs but lower stability (manalu et al., 2022; shi et al., 2011). in order to improve the performance of the pseudocapacitor, more research is required. transition metal oxides, such as ruo2, mno2, co3o4, and nio, are regarded as the most promising candidate for pseudocapacitors due to their capacitance, which is many times that of carbon materials (karimi et al., 2022). using ni and co ions, nico2o4 can currently be utilized as a supercapacitor electrode with extremely high performance. additionally, these electrodes are abundant in nature, eco-friendly, and possess low toxicity (km et al., 2022) . according to liu et al. (2021) , nickel and cobalt-based oxide/hydroxide composites are commonly employed as electrode precursors as a potential cost-effective substitute for ruo2. in recent years, nico2o4 has gained significant interest as an electrode material for high-performance supercapacitors, as it has been developed to be optimal for this purpose. furthermore, according to various earlier investigations, nico2o4 has superior electrical conductivity over nio and co3o4 (lee et al., 2019) . many studies have been conducted on transition metal oxides, binary transition metal oxides, and their combination with rgo for producing energy storage device materials (wang et al., 2015) . graphene is an exciting form of carbon due to its high volume-to-surface ratio and high conductivity. it possesses important qualities for achieving high energy storage capacities and power densities in supercapacitors. as a material for energy storage, graphene’s flexibility and electrochemical properties have been intensively investigated (nakhodchari et al., 2023) . metal-based rgo nanocomposites have effectively exhibited multiple applications, such as sodium-ion batteries, hybrid supercapacitors, wastewater treatment, and photocatalytic properties. rgo also supports rapid faradic oxidation-reduction processes at the electrode surface, which adds to a high energy density relative to carbon-based materials and a significant charge storage (saikia et al., 2020) . to maximize the performance of nico2o4 supercapacitors, additional work is required to improve their stability. diverse nanostructures can be fabricated using hydrothermal, chemical immersion deposition, adsorption, and ion coating reactions. these synthesis techniques can control the shape and size of nanoparticles. during the synthesis process, organic capping agents such as polyethylene-glycol (peg), polyvinylpyrrolidone (pvp), and trisodium citrate (tsc) alter the shape of nanomaterials (dong et al., 2011) . trisodium citrate has been used extensively as a form guide in fabricating several metal oxide nanostructures (han et al., 2013) . xing et al. (2012) manufactured mesoporous -ni(oh) 2 and nio nanospheres using ammonia and citrate using a hydrothermal method heated at 100 °c for 24 hours; the nanospheres exhibited a specific capacitance of 290 f g−1. with the addition of trisodium citrate to hierarchical nio nanospheres, han et al. (2013) discovered that the supercapacitor has a very high performance with a specific capacitance of 463 f g−1 at 4.5 a g−1 (90% capacity). in contrast, nio without trisodium citrate only has a specific capacitance of 182 f g−1 at 4.5 a g−1. this study applied trisodium citrate to nico2o4 nanomaterial electrodes as supercapacitor material. therefore, this study aims to characterize the modified material for further use as a supercapacitor material. characterization tests conducted with various instruments determined the morphological structure and the successful synthesis of nico2o4 with trisodium citrate. as a preliminary study, this current study does not provide a test for supercapacitor application as the relevant study must be separated since it needs comprehensive related tests. 2. experimental section 2.1 materials and instrumental the materials used were nickel(ii) nitrate hexahydrate (ni(n o3) 2.6h2o), cobalt(ii) nitrate hexahydrate (co(no3) 2·6h2o), ammonium fluoride (nh4f), trisodium citrate (na3c6h5o7), concentrated sulfuric acid (h2so4), phosphoric acid (h3po4), graphite powder, potassium manganate (kmno4), hydrogen peroxide (h2o2), ammonium hydroxide (nh4oh), sodium hydroxide (naoh), and ethanol (c2h5oh). these materials were obtained from merck, germany. meanwhile, the instruments used for the characterization of the nico2o4 sample with trisodium citrate (tsc) were sem (scanning electron microscope, fei quanta 650 feg), x-ray diffraction (xrd, philips xrd x’pert ms), fourier transform raman spectroscopy (ft-raman, raman ihr320 horiba), and fourier transform infrared spectroscopy (ftir, 8201 pc shimadzu). 2.2 methods 2.2.1 synthesis of nico2o4 with tsc the manufacture of nico2o4 with trisodium citrate (tsc) adheres to the method developed by paliwal and meher (2020) . with steady stirring, 35 ml of dilute ni(no3) 2.6h2o (2 mmol) solution was mixed with 55 ml of dilute co(no3) 2.6h2 o (6 mmol) solution. a 50 ml aqueous solution of nh4f (16 mmol) and varying amounts of tsc (0.5, 1, and 2 mmol) were sequentially added to the mixture (see table 1). using an aqueous naoh solution (1.0 m), the ph of the resultant solution was raised to 11. the solution was heated at 160°c (5°c min−1) for 24 hours in an autoclave coated with teflon and stainless steel. the product in the autoclave was cooled to © 2023 the authors. page 246 of 251 manalu et. al. science and technology indonesia, 8 (2023) 245-251 ambient temperature, and the precipitate formed was washed sequentially with water, a combination of water and ethanol, and 100% ethanol using a 5000 rpm centrifuge. the product was subsequently dried at 60°c in a vacuum oven, and the resulting product was treated to a 3-hour heat treatment at 350°c (using a heating path of 5°c min−1) under an ambient atmosphere. a black powder product identified as nico2o4 with tsc was obtained. nico2o4 without tsc, also known as nico2o4 pristine, was used for comparison. 2.2.2 synthesis of n-rgo (reduced graphene oxide) n-rgo was produced using the streamlined hummers method (shm). in the first step, 2 g of fine graphite powder was agitated slowly in a 9:1 (v/v) solution of concentrated h2so4 and h3po4 at 50°c for two hours. slowly, 9 g of solid kmno4 was added to the colloid, and the solution was heated at 50°c for 15 hours. after the reaction, a brown colloid was formed, rapidly cooled to 10°c, followed by the dropwise addition of h2o2 solution (5 ml) with continual stirring. the resulting brown colloid was rinsed with distilled water, 30% hcl, and 100% ethanol. the resultant substance is dried in a vacuum oven at 60°c for 12 hours. in the second stage, 150 mg go was dispersed in 30 ml water using ultrasonication, and then 8 ml of nh4oh solution was gently added to the resulting go suspension. the resultant suspension was then autoclaved at 180°c for 12 hours, separated using a centrifuge at 5,000 rpm, and washed with water, a water-ethanol mixture, and 100% ethanol. overnight, the final product was dried in a vacuum oven at 60°c. the obtained product was eventually labeled as n-rgo. table 1. variations of tsc composition in nico2o4 sample label composition of nico2o4 : rgo : tsc (mmol : mmol : mmol) pristine 1: 1: 0 0.5 mmol tsc 1: 1: 0.5 1 mmol tsc 1: 1: 1 2 mmol tsc 1: 1: 2 3. results and discussion 3.1 fabrication of nico2o4 nanoparticles with tsc the widespread use of nico2o4 nanosheets as the primary material for supercapacitor electrodes has been accompanied by low stability. this current study used tsc as a delayed chemical deposition agent on ni2+ and co2+ in conjunction with nh4f as a pseudo-capping agent, a molecule that prevents particle aggregation under hydrothermal conditions (jiang et al., 2022) . figure 1 depicts a schematic of the synthesis of nico2o4 using tsc as a supercapacitor material. at 150°c, ni2+ and co2+ ions combine with oh− ions to generate nico precursor crystallites. additionally, adding oh− ions causes co2+ ions to precipitate into co(oh) 2 slowly, generating nascent crystallites figure 1. manufacturing scheme of nico2o4 nanoparticles with trisodium citrate (tsc) distinct from the co precursors (lamba et al., 2022) . during the process, the pseudo-capping agent (nh4f) decomposes, reducing the ph and producing a new crystal precursor called co/coni. in addition, ostwald’s slow anisotropic ripening theory was utilized to determine the transition of co/nico precursors into sheet precursors (chai et al., 2022) . due to high temperatures, tsc is subsequently ionized as [c6h5o7] 3− ions, stacked nanosheets capable of reducing hydrogen bonds between layers (bhardwaj and jha, 2020) . ft-raman tests on rgo/go and sem, ftir, and xrd analysis on the obtained materials were performed to validate the phase and microstructural properties of the synthesized materials. 3.2 sem characterization the objective of the sem analysis is to observe the morphology of nico2o4 with tsc at 1 `m magnification. figure 2 demonstrates the results of the sem analysis. according to sem images in figure 2.a, nico2o4 nanoparticles have a consistent nanowire-like structure. in agreement with the findings of km et al. (2022) , nico2o4 nanowires are embedded in a homogenous nanoparticle framework. the advantages of this homogeneous structure can lead to a short ion transport length and a large specific surface area, resulting in the growth of contiguous electrolyte domains. after the addition of tsc to the nico2o4 nanoparticles, it was discovered that the addition of 0.5 mmol tsc resulted in a very messy morphological structure (figure 2.b), the addition of 1 mmol tsc resulted in a neat, more uniform structure that resembled a solid crystal (figure 2.c), and the addition of 2 mmol tsc resulted in the largest structure. however, the nanoparticles’ crystal clarity of 2 mmol tsc sample was poorer than that of 1 mmol tsc sample (figure 2.d). according to offor et al. (2021) , the denser the morphological structure and the greater the particle size, the higher the tsc addition concentration. therefore, adding 1 mmol tsc to nico2o4 nanoparticles produces the ideal morphological shape, as the structure becomes denser, softer, and more regular. 3.3 xrd characterization xrd analysis aims to determine whether or not nico2o4 nanoparticles contain tsc qualitatively. figure 3 illustrates © 2023 the authors. page 247 of 251 manalu et. al. science and technology indonesia, 8 (2023) 245-251 figure 2. sem images of (a) pristine, (b) 0.5 mmol tsc, (c) 1 mmol tsc, and (d) 2 mmol tsc the xrd patterns. according to figure 3, almost all of the data do not exhibit differences, or their characteristic peaks had the same pattern, except for the pristine sample, which had a lower peak than the addition of tsc. this suggests that adding tsc does not alter or degrade the crystallinity of the nico2o4 nanoparticles but somewhat improves it. the sem analysis confirmed that adding 1 mmol of tsc resulted in a consistent, orderly, and smooth arrangement of nanoparticles. the xrd diffraction patterns at 2\ angles, 45.04 and 53.34° fit the plane of the cubic phase nico2o4 nanorod crystals with values 400 and 511, respectively, as confirmed by jcpds card no. 20-0781. according to research by salarizadeh et al. (2020) , the angles of nico2o4 nanoparticles at 2\ are 44.54 and 59.16°. even though just two significant peaks are evident on the diffractogram, it may be assumed that the identification of tsc on nico2o4 was effective, indicating that it did not disrupt or alter the crystalline structure of nico2o4. according to figure 3, the nico2o4/rgo composite exhibited no carbonrelated distinctive peaks in its xrd pattern. this is owing to the ability of nico2o4 to diminish the strength of rgo diffraction. in addition, ft-raman spectrum analysis demonstrates the presence of rgo (du et al., 2016) . 3.4 raman characterization rgo and go were analyzed with ft-raman equipment to determine the nature of the bonding. figure 4 displays the results of the ft-raman spectroscopic analysis. according to the investigation results, the distinctive spectra of rgo and go are very characteristic around 1360 (d band) and 1595 (g band) cm−1 for the raman shift. this shows that rgo and go molecules contain c=c double bonds. the peak of the raman g band results from the in-plane motion of sp2 carbon, whereas the peak of the raman d band results from out-ofplane (sp3) vibrations (salarizadeh et al., 2020) . in contrast, the strength of the rgo peak in the raman spectrum is greater than that of the go peak. this is consistent with aksu et al. figure 3. xrd pattern of pristine (black), 0.5 mmol tsc (red), 1 mmol tsc (blue), and 2 mmol tsc (pink) (2022) , who compared rgo and go using raman instruments and revealed c=c bonds with greater peak intensities in rgo. adding rgo to nico2o4 nanoparticles is intended to improve their electrical conductivity by facilitating charge transfer and promoting uniform material development (singh et al., 2020) . the synergistic impact of nico2o4 sheet and rgo facilitates rapid electronic diffusion, hence enhancing velocity capability and surface activity for charge storage (jiang et al., 2018) . this is also consistent with the findings of du et al. (2016) , who found that rgo addition on nico2o4 of supercapacitors can reach a power conversion efficiency of 6.17%, but without rgo, it is only 5.21%. without rgo on nico2o4 nanobelts, they tend to congregate and create sarciniform patterns rather than spread out. with the addition of rgo, the nico2o4 nanoparticles dispersed equally across the graphene sheet. in addition, due to the presence of rgo, the composite’s efficiency and stability are enhanced. 3.5 ftir characterization functional groups in nico2o4 nanoparticles were identified using ftir before and after the material synthesis. figure 5 illustrates the ftir results of the modified nico2o4 before and after the addition of tsc. comparing the ftir spectra before and after the addition of tsc reveals that some vibration spectra shift to longer or shorter wavenumbers while others appear. at wavenumbers of 1550-1600 cm−1, it is either a c=c functional group in an aromatic ring or a c=o 𝜋-𝜋 structure, a bond from rgo (aman et al., 2022) . this was strengthened by pristine, nico2o4/rgo nanoparticle, while adding 0.5, 1, and 2 mmol causes a shift, and the peak of the c=c functional group weakens or competes with tsc, which possesses the c=o functional group. a possible cause is the existence of a tsc molecule that degrades rgo, allowing tsc to predominate. a peak confirms this assertion at around 2300 cm−1, © 2023 the authors. page 248 of 251 manalu et. al. science and technology indonesia, 8 (2023) 245-251 figure 4. ft-raman analysis on rgo (black) and go (red) corresponding to the oh group in tsc, an alkanoate derivative. more moles of tsc added to nico2o4 nanoparticles will result in sharper peaks. the 2 mmol tsc has the clearest peak ir spectrum compared to the others. at around 1500 cm−1, a tiny peak corresponds to the co-o bond in nico2o4 (aman et al., 2022) . the functional groups on nico2o4 nanoparticles containing rgo as pristine and tsc may be detected using ftir analysis. assuming that tsc has been effectively produced on nico2o4 nanoparticles, the results of other characterization experiments with different instruments have also been evaluated. however, additional testing is required to determine the stability of nico2o4 nanoparticles with tsc. figure 5. ftir spectra of pristine, 0.5 mmol tsc, 1 mmol tsc, and 2 mmol tsc 4. conclusion the characterization tests conducted using sem, xrd, ftraman, and ftir indicate that nico2o4 has been successfully synthesized utilizing tsc. at xrd, the angles of 2\, namely 45.04 and 53.34°, matched the plane of the cubic phase nanorod crystals of nico2o4 with values of 400 and 511, respectively. in the raman study, the presence of rgo, which increased the crystallinity of nico2o4 nanoparticles, was confirmed. ftir analysis determined that the 1550-1600 cm−1 corresponds to a c=c functional group in an aromatic ring or a c=o 𝜋-𝜋 structure, and the wavenumber of 2300 cm−1 corresponds to the oh group in tsc, which is an alkanoate derivative. sem analysis determined that nico2o4 nanoparticles with 1 mmol tsc are the best-comparing material for supercapacitor electrodes, as the structure is the most uniform, soft, and tidy. in addition, if the energy is stable, it is possible to stabilize the structure to store energy and process heat. therefore, further analysis is needed to confirm the stability of the obtained materials. 5. acknowledgment the authors would like to thank the physics laboratory of universitas hkbp nommensen pematangsiantar and the physics laboratory of the national research and innovation agency (brin) for providing facilities and instrumental analysis in this research. references abdah, m. a. a. m., n. h. n. azman, s. kulandaivalu, and y. sulaiman (2020). review of the use of transitionmetal-oxide and conducting polymer-based fibres for highperformance supercapacitors. materials & design, 186; 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5784–5790 winter, m. and r. j. brodd (2004). what are batteries, fuel cells, and supercapacitors? chemical reviews, 104(10); 4245–4270 xing, s., q. wang, z. ma, y. wu, and y. gao (2012). con© 2023 the authors. page 250 of 251 manalu et. al. science and technology indonesia, 8 (2023) 245-251 trolled synthesis of mesoporous 𝛽 -ni (oh) 2 and nio nanospheres with enhanced electrochemical performance. materials research bulletin, 47(9); 2120–2125 zheng, h., x. du, q. liu, k. ou, y. cao, x. fang, q. fu, and y. sun (2023). self healing and wide temperature tolerant flexible supercapacitor based on ternary-network organohydrogel electrolyte. internationaljournalofhydrogenenergy, 3(5); 34–39 © 2023 the authors. page 251 of 251 introduction experimental section materials and instrumental methods synthesis of nico2o4 with tsc synthesis of n-rgo (reduced graphene oxide) results and discussion fabrication of nico2o4 nanoparticles with tsc sem characterization xrd characterization raman characterization ftir characterization conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper development and validation gc/ms method for methamphetamine analysis in urine by miniaturization quechers soraya aulia1,2, riesta primaharinastiti1, djoko agus purwanto1* 1magister of pharmaceutical science, airlangga university, nanizar zaman joenoes building, campus c, mulyorejo, surabaya, 60115, indonesia2laboratory of chemistry and toxicology, laboratory center of health, testing and calibration, west nusa tenggara provincial health office, caturwarga street number 4, mataram, 83121, indonesia *corresponding author: djokoagus@ff.unair.ac.id abstractthis paper explains the development of a quick and easy gas chromatography (gc) approach to identify methamphetamine in urine.this research used gas chromatography with mass spectroscopy and a capillary column tg-5silms (5% phenyl methyl siloxane, 30m x 0.32 x 25 m). the carrier gas flow rate was set at 1.0 ml/minute, the temperature inlet and detector had been set at 300°c,and the oven temperature was programmed to initiate at 50°c and held for 1.5 minutes before being raised to 300°c at a rate40°c/minute and held for 3 minutes. sample pre-treatment by modification of the quechers method includes using a relativelylarge amount of inorganic salt, extraction volume and extraction cycle. the optimal conditions for processing a 400 `l urine samplewere 160 mg magnesium sulphate, 40 mg sodium chloride, and 400 `l acetonitrile for organic solvent. according to the validationtest, the detection limit for methamphetamine was 0.36 `g/ml; the quantitation limit was 1.09 `g/ml, and the calibration curvefollowed the regression line. y=1.0489x-3.7914, coefficient (r) was 0.9973. the recovery of the analyte spiked into urine at 5, 7and 9 `g/ml on average was 100.5±2.33% for intraday dan 93.3±7.21% for interday. the precision was excellent, with an averagecoefficient of variation of 2.31%. the procedure was applied to four urine samples from drug users and the first abuser (25.51 `g/ml),the second abuser (15.05 `g/ml), the third abuser (17.72 `g/ml) and the last abuser (3.08 `g/ml) were all satisfactorily quantitated. keywordsgc-ms, quechers, urine, methamphetamine, validation received: 4 march 2023, accepted: 15 june 2023 https://doi.org/10.26554/sti.2023.8.3.451-460 1. introduction as a world body dealing with narcotics issues, the united nations office on drugs and crime (unodc) notes that at least 271 million people worldwide, or 5.5% of the total global population aged 15 to 64 years, have consumed drugs, with at least one person having consumed narcotics in 2017. at the end of 2019, indonesia’s population reached ±271 million people, of which 3.41 million people or around 1.80%, were drug abusers (national, 2019) . the use and abuse of methamphetamine have been on the rise for a decade. based on data from the criminal investigation agency of the republic of indonesia police, in 2019, the distribution of methamphetamine-type drugs reached 2.7 tons, and in 2020 it increased by 119% to 5.91 tons (dalimunthe et al., 2019) . methamphetamine is an illegal drug that is very dangerous and damaging. the active compound in methamphetamine can stimulate the central nervous system (cns), so its distribution is prohibited in indonesia, so the government takes this matter seriously by issuing law number 35 of 2009 concerning narcotics as a legal basis that the distribution and abuse of narcotics is an activity that is against the law, which is determined as a crime. methamphetamine is an amphetamine that has a methyl substituent in the amino group (s)-amphetamine. it is a neurotoxin, a psychotropic medication, a central nervous system stimulant, a xenobiotic, and an environmental pollutant (rothman et al., 2001) . drug compounds can be monitored through body fluids such as urine, sweat, saliva, and blood. methamphetamine is excreted in the urine about 70% of the dose within 24 hours, 30-50% as methamphetamine, and 10-15% as its metabolite. metabolites of methamphetamine in urine are amphetamine and 4-hydroxy methamphetamine (cruickshank and dyer, 2009; kim et al., 2004). the percentage of parent methamphetamine in the urine is large enough so that a methamphetamine test using a urine sample can be performed. in addition, urine is easy to obtain and does not require expertise to get it (volkow et al., 2010) . https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.451-460&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.451-460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 before carrying out an analysis of the concentration of methamphetamine in urine samples using sophisticated inspection techniques such as gas chromatography, the process of purifying methamphetamine from urine samples is a process that must be followed. analyte extraction and purification are critical in detecting medicines and metabolites in biological materials. traditional sample extraction or purification methods such as liquid-liquid extraction (lle) or solid phase extraction (spe) consume much time, have many steps and are quite complicated, require a variety of chemicals and in large enough quantities, the risk loss of analyte or contamination higher and not quite safe for the environment because the waste produced is quite high (campêlo et al., 2021; correiasá et al., 2018; maggira and samanidou, 2018; stevens and jones, 2010; westland and dorman, 2013). another problem also comes from the biological sample itself, where the concentration of methamphetamine in the urine is very small (trace analyte), and the biological sample has a very complex matrix (carasek et al., 2022; lawal et al., 2018; seidi et al., 2019). anastassiades et al. (2003) developed the quechers (rapid, easy, cheap, effective, rugged, and safe) approach for evaluating pesticide residues in fruits and vegetables. through quechers, the previously complicated method can be simplified into two easy steps; the first stage through liquid-liquid extraction and the second stage through the solid phase. further analysis was carried out using gas or high-performance liquid chromatography (numbers, 2017) . the quechers method is similar to lle but highly selective, like spe. the quechers method involves extracting the sample with acetonitrile or ethyl acetate solvents and dehydrating it in salts such as magnesium sulphate and sodium chloride (asl et al., 2017) . several studies have been carried out to modify the quechers method by fanning et al., where they reduced the use of magnesium sulphate and sodium chloride salts from the previously commonly used 4g magnesium sulfate:1 gram sodium chloride to 800mg:200mg due to the use of the sample, which is also less, likewise, with the use of acetonitrile which is reduced proportionally. from the results of this study, the recovery results were quite good, namely an average of 81% and 83% from two different analyte concentrations and the average of various types of drugs in beef liver samples (numbers, 2017) . asl et al. (2017) , carried out another study. they used 400mg of magnesium sulphate and 200mg of sodium chloride with a volume of 1 ml of the urine sample and added buffer until the sample ph became 8-9. this study produced a fairly good recovery value of 78% (asl et al., 2017) . numerous investigations have been conducted to modify and optimize the quechers method, including optimizing the use of solvents and partition salts based on the target analyte to be analyzed, as well as modifications to the use of sorbents as clean-ups and, finally, through miniaturization of quechers. the various quechers modifications aim to increase extraction effectiveness, reducing the influence of the sample matrix and increasing selectivity, specificity and sensitivity (schmidt and snow, 2016) . figure 1. overlay 10 `g/ml methamphetamine chromatogram method 1, 2, and 3 in acetonitrile using gas chromatography. the quechers modification is also very important, especially when the number of samples available is limited, and is very popular in analytical chemistry because of its advantages such as lower solvent, salt, and sorbent costs, simpler handling, processing, and elimination of waste when compared to traditional extraction procedures. this feature provides higher throughput analysis, resulting in increased accuracy and significant savings in time and expense. the development of the quechers technique pushes the issue of miniaturization and automation even further (perestrelo et al., 2019) . several studies in the forensic field have been carried out to modify quechers through miniaturization of quechers, but the derivatization and evaporation stages are still being carried out (amorim alves et al., 2017;matsuta et al., 2013; pouliopoulos et al., 2018). based on the description above, it is necessary to conduct research related to modifying quechers through miniaturization of quechers (m-quechers) to extract methamphetamine in urine before being analyzed using gas chromatogr aphy-mass spectroscopy. compared to the previous existing research, the novelty in this study is simplifying the extraction process by not carrying out the derivatization step but still considering the selectivity, specificity, sensitivity, accuracy and precision of an analytical method. 2. experimental section 2.1 materials 2.1.1 reagents and materials acetonitrile, mgso4, nacl and potassium carbonate were purchased from merck indonesia. the standard methamphetamine hydrochloride 1000 `g/ml in methanol was purchased from cayman chemical. the internal standard (caffeine solution 1000 `g/ml in methanol) was purchased from supelco (usa); the remaining reagents and solvents used were © 2023 the authors. page 452 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 figure 2. methamphetamine recovery diagram by the m-quechers method. red, extraction volume 400 `l with extraction cycles 2 times (e2.2) and 3 times (e2.3). orange, extraction volume 800 `l, extraction cycle 1 time (e3.1), 2 times (e3.2) and 3 times (e3.3). green, extraction volume 1200 `l, extraction cycle 1 time (e4.1), 2 times (e4.2) and 3 times (e4.3) of analytical grade or above. water that has been deionized and distilled (millipore system). disposable 2 ml safe-lock test tube and 15ml tubes with screw cap (eppendorf, germany). 2.1.2 urine samples the sample to be used in this study was random urine. negative urine for methamphetamine was obtained from volunteers (laboratory staff) who had not taken any medication in the past month. 2.2 methods 2.2.1 sample preparation method magnesium sulphate and nacl were crushed and thoroughly combined in a weight ratio of 4:1. the mixture was weighed into disposable 2 ml safe lock test tubes (200 mg each, 5 mg). a 400 `l of acetonitrile was poured into disposable 2 ml safe lock test tubes holding the mgso4 and nacl combination. a 400 `l urine sample was adjusted to a ph of more than 10 using k2co3 buffer and placed in the test tube. immediately vortex-mixed for 1 minute, then centrifuged at 10.000 rpm for 5 minutes using a high-speed refrigerated centrifuge mpw-150 (med. instrument, polandia). a pipette was used to separate the organic phase. to recover the organic extract contained in the cake of an inorganic salt, 400 `l of acetonitrile was added to the test tube, and the organic phase was sampled after vortexing and decanting twice. these organic extracts were mixed and evaporated in a gentle nitrogen stream. the recovered residue was dissolved in 400 `l of acetonitrile. (correia-sá et al., 2018; numbers, 2017; asl et al., 2017; matsuta et al., 2013; schmidt and snow, 2016; westland and dorman, 2013). figure 3. chromatogram of a standard solution of methamphetamine 10`g/ml in acetonitrile with a value of tr (minutes) = 5.013 and 7.013 for is (caffeine) 2.2.2 gc-ms sample injection was done manually with a volume of 1 `l. the analyte was separated using a tracegold tg-5silms capillary column (0.25mm. id, 30m, 0.25µm with 5m safeguard), and the mobile phase was helium (purity ≥99.999%). the flow rate of the carrier gas is 1 ml/minute constantly by the system, splitless injection mode. the oven temperature was programmed to follow the coa reference, which was 50°c for 1 minute, then increased at 40°c/minute until it reached 300°c. at the end of the analysis, the conditions were set at 300°c for 3 minutes to eliminate the effects of impurities from the sample. injector temperature and ms transfer line temperature were set at 300°c. the ms ionization system used electron impact (ei) with a strength of 70ev at 300ºc. the thermo scientific chromeleon chromatography data system (cds) software is used for data processing and operational systems. 3. results and discussion 3.1 optimization of gc-ms conditions the conditions were optimized by adjusting the rate of increase in oven temperature, gas flow rate, injection mode and sample volume. in this research, there are three different optimization methods. method 1 uses a sample volume and flow rate of 1 `l with a temperature increase of 40°c. in methods 2 and 3, the sample volume is 2 `l with a flow rate of 1.5 `l, but the speed of temperature rise is different, namely 40°c for method 2 and 30°c for method 3. from table 1 and figure 1, the retention time (tr) of methamphetamine was 5.095 minutes, and is was 7.020 for method 1. method 2 showed methamphetamine’s tr was 5.064 minutes and is 7.023, while method 3 showed methamphetamine’s tr was 5.390 minutes and is 7.993. the results of gas chromatography optimization were assessed from several parameters, namely resolution, theoretical plate number and match factor, which can be seen in table 1 (granquist et al., © 2023 the authors. page 453 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 table 1. results of optimizing the determination of methamphetamine levels with is caffeine in several gas chromatography conditions method optimization results parameters flow temperature injection sample relative resolution theoritical relative mf* run rate rising mode volume retention met/is* plate area met time (ml/min) speed (`l) time met/is (min) numbersmet./is met/is* (min) 1 1 40°c/min splitless 1 1.38 3.85/2.06 254524/ 1381146 1.24 885 11.21 2 1.5 40°c/min splitless 2 1.39 5.08/1.88 289549/ 1268266 1.33 895 11.21 3 1.5 30°c/min splitless 2 1.49 3.53/4.55 123300 / 2114975 2.16 915 13.31 *mf = match factor; met = methamphetamine; is = internal standard (caffeine) figure 4. chromatogram of the methamphetamine solution extracted from urine in acetonitrile solution with a value of retention time/tr (minutes) 5.016 and resolution (rs) 4.62. for is (caffeine), tr (minutes) 7.016 and resolution (rs) 2.07 2019) . the result of optimizing the selected gas chromatography conditions was method 1: an initial temperature of 50°c for 1 minute with a temperature increase of 40°c/minute until it reaches 300°c, which is maintained for 3 minutes. the inlet temperature was 300°c, the splitless mode, and the gas flow rate was 1.0 ml/minute. method 1 was chosen because it has several advantages compared to methods 2 and 3; among others, the gas flow rate and sample volume were less than methods 2 and 3, namely 1 ml/minute, with a shorter run time and faster retention time of analyte and is, but still shows the same optimization results as both methods 2 and 3. methods 1, 2 and 3 show a resolution value of 3.85, 5.08 and 3.53, where the three values meet the requirements for good analyte resolution, which is greater than 1.5. likewise, with the theoretical plate number, which showed a value greater than 10,000, the column can separate the analyte from the mixture. the match factor (mf) value showed the similarity of the analyte spectrum with the reference spectrum in the library, which can be seen in table 1; the three methods showed an mf value of > 800, which means that the level of similarity is good according figure 5. mass spectrum of methamphetamine in urine (a) with rt = 5.02; mass spectrum methamphetamine in urine versus nist library database (b) with mf = 923 and mass spectrum methamphetamine nist library database (c) with mw = 149 to the nist library guidelines (gujar et al., 2018) . 3.2 optimization of extraction method the selection of inorganic salts in the modification of quechers in this study was based on the original method of quechers, which used mgso4 and nacl with a ratio of 4:1, and the balance of sample volume to solvent was 1:1 (schmidt & snow, 2016). extraction optimization was done by modifying several extraction parameters: the number of inorganic salts, extraction volume and extraction cycle. differences in variation can be seen in table 2. the results of standard extraction of 10 `g/ml metham© 2023 the authors. page 454 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 table 2. variation of methamphetamine extraction volume with inorganic salt composition: urine volume: acetonitrile = 1:2:2 sample id weight of urine acetonitrile extraction extraction inorganic volume volume volume cycle salt* (mg) (µl) (µl) (µl) extraction 50 100 100 200 1 (e1) 2 3 extraction 100 200 200 400 1 (e2) 2 3 extraction 200 400 400 800 1 (e3) 2 3 extraction 300 600 600 1200 1 (e4) 2 3 *inorganic salt = mgso4:nacl (4:1) figure 6. methamphetamine calibration curve for determination of linearity, lod and loq phetamine in urine with several variations in extraction volume can be seen in table 3, where the relative area was obtained from the ratio of the methamphetamine area to the is area, then %cv and %recovery (%r) was calculated (campêlo et al., 2021) . the recovery percentage was calculated from the ratio of the relative area of the analyte in the spiked sample after extraction to the relative area of the standard at the same concentration (orfanidis et al., 2022) . table 3 shows that for the e1 method, injection into the gas chromatography was not carried out because it was difficult to separate the organic phase from the aqueous phase. after all, the extraction volume was very small, namely 100 `l, so the analysis results were not obtained. extraction method 2 with one extraction cycle was also not analyzed using gas chromatography because the organic phase produced was cloudy after the evaporation and restitution process using acetonitrile, which was feared would figure 7. methamphetamine concentration reduction curve during storage at room temperature 30°c at storage times of 0, 2, 4, and 8 hours clog the gas chromatography column (matsuta et al., 2013) . it can be seen in figure 2 that the extraction that gives the best % recovery results is the e3 extraction volume (800 `l) for three extraction cycles with a %r of 101.2 ± 2.30% and a %cv of 2.27%. according to orfanidis et al. (2022) , recoveries of the analyte were satisfactory was more than 85%. the next extraction stage was performed using these conditions (orfanidis et al., 2022) . 3.3 qualitative test of methamphetamine in urine samples by gc-ms the two chromatogram images (figure 3 and figure 4) showed that the standard methamphetamine retention time is 5.013 minutes, and in the urine sample is 5.016 minutes. the relative retention time for the solution and the methamphetamine in the urine sample was 0.71. the ratio of methamphetamine © 2023 the authors. page 455 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 table 3. optimization results of methamphetamine extraction, mean relative area of methamphetamine to is (n=3), recovery ± sd (%) and coefficiency of variation (%cv) method extraction visual mean relative recovery ± sd %cv cycle (times) area met./is (%) e1 1 the organic phase n.a n.a n.a 2 layers are difficult to n.a n.a n.a 3 separate n.a n.a n.a e2 1 cloudy organic phase n.a n.a n.a 2 clear organic phase 0.24 12.28 ± 1.10 8.92 3 0.31 15.57 ± 0.60 3.85 e3 1 clear organic phase 0.58 28.96 ± 1.94 6.70 2 0.67 33.46 ± 4.78 14.3 3 2.01 101.2 ± 2.30 2.27 e4 1 clear organic phase 1.59 79.89 ± 12.89 16.14 2 1.69 85.35 ± 5.28 6.19 3 1.77 88.83 ± 6.17 6.95 n.a = not available = no analysis was performed by gc-ms table 4. the relative area of methamphetamine to is sample blank, internal standard (is), standard 1 to standard 6 (std 1 std6), mean, %cv and %bias (n=3) blank is std 1 std 2 std 3 std 4 std 5 std 6 concentration (`g/ml) 0 2.5 5 6 7 8 9 10 replication 1 0.07 0.16 1.28 2.28 3.70 4.60 5.80 6.60 replication 2 1.24 0.16 1.44 2.55 3.95 4.59 5.87 6.58 replication 3 0.67 0.19 1.43 2.52 3.49 4.65 5.50 6.56 mean 1.38 2.45 3.71 4.61 5.72 6.58 %cv 6.48 6.04 6.20 0.70 3.43 0.30 %bias 1.39 0.83 2.17 0.12 0.76 1.12 retention time to is (caffeine) retention time yields the relative retention time. based on the two values, the relative retention times of standard methamphetamine and urine samples are the same. the results of identifying the mass spectrum of methamphetamine in urine compared to the mass spectrum of methamphetamine in the nist library database are in figure 5. the best compound identification is generally assessed from the highest match factor (mf), which represents the suitability between the measured compound spectrum and the reference spectrum. for this reason, this study used the nist library guidelines to interpret the mf values of the analytes tested as a reference for interpreting the quality of the mass spectra of analytes. based on the standard chromatogram of methamphetamine in urine samples, the five highest m/z values were for methamphetamine, namely 58, 91, 56, 65 and 42. figure 5 shows that the mf value for methamphetamine was 923 (excellent match). an excellent match means that the analyte (methamphetamine) was identical to the nist library database (gujar et al., 2018) . 3.4 validation method the validation method was carried out by assessing several analytical parameters based on the bioanalytical method validation m10 by international council for harmonisation (ich), european medicines agency (guideline, 2019) , such as selectivity, specificity, linearity, limit detection, limit quantitation, effect matrix, carry-over, accuracy and precision. 3.4.1 selectivity the evaluation of selectivity using samples of methamphetamine containing is, then the calculation of resolution (rs) values of methamphetamine and is against other closest components. the value of rs for methamphetamine was 4.62, and the is was 2.07. based on these resolution values, it concluded that the method is selective because it can separate the methamphetamine peaks from the peaks of other components with a value of rs > 1.5 (woźniak et al., 2018) . 3.4.2 specificity the specificity analysis showed the absence of other components that interfere with the retention time of methamphetamine and is retention time in the blank sample. in ad© 2023 the authors. page 456 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 table 5. accuracy (%r ± sd) and precision (%cv) test results intraday and interday (n=3) true value intraday interday (µg/ml) mean concentration %cv %r ± sd mean concentration %cv %r ± sd (µg/ml) (µg/ml) 5.0 4.93 1.77 98.7 ± 1.75 4.98 4.85 99.6 ± 4.83 7.0 7.15 3.06 102 ± 3.14 5.95 3.89 85.0 ± 3.32 9.0 9.07 2.08 101 ± 2.10 8.57 14.0 95.2 ± 13.5 table 6. stability test results, %cv and % reduction in methamphetamine concentration during storage time of 0, 2, 4 and 8 hours (n=3) time (hour) mean concentration (µg/ml) sd %cv % reduction 0 4.38 0.056 1.27 2 4.30 0.010 0.24 1.95 4 4.24 0.041 0.97 3.35 8 4.05 0.240 5.90 7.80 dition, specificity can also assess the relative retention time of methamphetamine to is in standard solution compared to a retention time relative to methamphetamine in a urine sample; both retention times are the same, namely 0.71. another evaluation of the specificity test is the match factor score (mf) (gujar et al., 2018) . where the mf score for methamphetamine using this method is 923 (excellent match), the results of which can be seen in the qualitative test (figure 5). the results from the specificity test show that the method used is specific (numbers, 2017) . evaluation of the selectivity and specificity for is are assessments of the value of rs for the internal standard is 2.07 > 1.5. there is a disturbing peak at is retention time, but the percentage of interfering response is 5.8%, which is not more than 20% of the is response at a concentration of 2.5 `g/ml. based on that evaluation, the conclusion is the method specific to is (guideline, 2019) . 3.4.3 linearity, detection limit, quantitation limit, and matrix effect the results of observing the peak area of methamphetamine from standard solutions for the determination of linearity, limit of detection (lod), the limit of quantitation (loq), and matrix effects can be calculated from the price of the sensitivity of the slope (sl) based on a comparison between levels and peak area as shown in table 4 and figure 6. the linearity of the method was studied within the range of the mean therapeutic concentration of methamphetamine, which was found in the literature (kim et al., 2004; volkow et al., 2010). every standard was analyzed in three replicates of the is. the correlation test results between variable x (concentration) and variable y (relative area) using spss 21.0, where the significance value = 0.000 is smaller than the value 𝛼 = 0.05, so there is a correlation or a relationship between concentration and relative area. the pearson correlation (r) = 0.996 shows a positive relationship with the degree of perfect correlation between concentration and relative area (samuels, 2015) . if the analyte concentration is high, the relative peak area of the analyte will also be higher. from table 4 and figure 6, it can be calculated that the price s(y/x) = 0.11443 and the slope value (sl) = 1.0489. lod is calculated from 3.3s(y/x)/slope and loq from 10s(y/x)/slope. therefore the detection limit value obtained is lod = 0.36 `g/ml and the quantity limit is loq = 1.09 `g/ml. table 4 shows the matrix effect of all concentration levels in the linearity range: an average accuracy value is 99.9%, while for precision, the average %cv value is 3.86%. the accuracy should be around 15% of the nominal concentration, and the precision (per cent coefficient of variation (%cv)) should not be more than 15% in all individual matrix sources/lots, according to ich guideline m10 on bioanalytical method validation. these results met its requirement, meaning components in the sample matrix do not disturb the analysis process (guideline, 2019) . 3.4.4 accuracy and precision (intraday and interday) determine the accuracy (% recovery) and precision (% coefficient of variation or %cv) through three concentration levels of methamphetamine were added to the urine, namely 5.0 `g/ml as a low concentration, 7.0 `g/ml as a middle concentration, and 9.0 `g/ml as a high concentration. the results of the accuracy and precision tests in table 5 are both carried out intraday (same day) and interday (three different days). table 5 shows that the %r intraday values at three concentrations were 98.7±1.75% at low concentrations, 102±3.14% at middle concentrations, and 101±2.10% at high concentrations. the %r interday at three concentrations were 99.6±4.83% at low concentration, 85.0±3.32% at middle concentration, and 95.2±13.5% at high concentration. the precision test at threelevel concentrations (%cv) for intraday analysis was 1.77% at © 2023 the authors. page 457 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 table 7. the area of methamphetamine in the blank sample followed the highest standard (10 µg/ml) and the percentage of the area of methamphetamine at a concentration of 3 µg/ml and to is at a concentration of 2.5 µg/ml methamphetamine internal standard (is) area analyte area analyte at 3 µg/ml % respon area analyte area is at 2.5 µg/ml % respon 45876 996692 4.60 37051 1519376 2.44 24074 996692 2.42 36198 1519376 2.38 162057 996693 16.3 44963 1519376 2.96 average of analyte response 7.76 average of is response 2.59 table 8. analysis results of methamphetamine in the urine of four patients who abuse methamphetamine using the rapid test method (immunoassay) and gas chromatography mass spectroscopy abuser rapid test result mean concentration of methamphetamine (µg/ml) duplicate sd %cv p1 positive 25.51 1.70 6.66 p2 positive 15.05 0.95 6.31 p3 positive 17.72 0.39 2.21 p4 negative 3.08 0.10 3.38 a low level, 3.06% at the middle, and 2.08% at a high level. the %cv interval at three concentrations was 4.98% at a low concentration, 5.95% at a medium concentration, and 8.57% at a high concentration. from the overall accuracy and precision test results both intraday and interday, the accuracy (%r) is between 85-115%, and the precision test (%cv) is <15%, so the m-quechers method used has high accuracy and precision (guideline, 2019;kaur and sharma, 2018). 3.4.5 stability test injections at one concentration level were stored for 2 hours to 8 hours at room temperature and replicated three times. the results of the stability test are in table 6. from the stability test, there was a decrease in the concentration of methamphetamine by 1.95% at 2 hours of storage, 3.35% at 4 hours, and 7.80% at 8 hours of storage. from the linear equation data on the graph, the stability of determining methamphetamine levels decreased by 0.041 `g/ml per hour (figure 7). this stability test result is a basis for analysis that urine samples must be processed immediately upon receipt because the concentration of methamphetamine will continue to decrease during storage at room temperature 30°c so that the measured concentration will be lower than the actual concentration (guideline, 2019; pouliopoulos et al., 2018). 3.4.6 carry over test throughout the validation procedure, the carry-over parameter is evaluated by examining the blank sample following the highest calibration standard for the analyte and internal standard to check for any variations in the measured concentration due to residual analyte from the prior sample remaining in the analytical equipment. following the highest standards, the carry-over in the blank sample should not be more significant than 20% of the methamphetamine response at 3 `g/ml and 5% of the is response at 2.5 `g/ml. table 7 shows the results of the carry-over test. the percentage area of methamphetamine in the blank sample following the 10`g/ml standard was an average of 7.76% of the peak area of methamphetamine at 3 `g/ml and 2.59% of the peak area of is at 2.5 `g/ml. these results indicated that minimalization of carry-over during the analysis process succeeded because the average percentage of methamphetamine and is responses is less than 20% (guideline, 2019) . 3.4.7 application of m-quechers method for methamphetamine determination in the urine of abusers determination of urine samples from 4 suspected methamphetamine abusers using a rapid test (immunoassay) method. the urine was extracted using the selected m-quechers method and injected into gas chromatography-mass spectrosco py. table 8 shows the results of methamphetamine determination in the urine of the abuser. the results of 4 urine samples of methamphetamine abusers, three samples (p1, p2, and p3) gave consistent results between the rapid test and the confirmatory test using gas chromatography-mass spectroscopy, but sample 4 (p4) could not detect methamphetamine levels which were too low so that there was a difference in results between the rapid test and the gas chromatography-mass spectroscopy test. the inability of the rapid test to detect methamphetamine may be due to abusers having used methamphetamine beyond their detection limit of 3-4 days. however, gas chromatography tests can still detect methamphetamine at 3.08 µg/ml levels (schmidt and snow, 2016) . 4. conclusion a rapid, selective, specific, and reliable method for analyzing methamphetamine in urine was developed. the validation © 2023 the authors. page 458 of 460 aulia et. al. science and technology indonesia, 8 (2023) 451-460 results of the m-quechers extraction method met the validation criteria according to the standard validation method, namely the ich guidelines bioanalytical method validation m10 on all aspects of the validation tested, namely selectivity and specificity, matrix effect, linearity, accuracy, precision, and carry over. the m-quechers method can be applied to routine laboratory testing to analyze methamphetamine in the urine of methamphetamine abusers. 5. acknowledgment this study received no specific financing from government, commercial, or non-profit organizations. we want to express our gratitude to the laboratory center of health, testing and calibration of west nusa tenggara province for facilitating the place and tools used in this research. references amorim alves, e., a. sofia agonia, s. manuela cravo, c. manuel afonso, a. duarte pereira netto, m. de lourdes bastos, f. carvalho, and r. jorge dinis-oliveira (2017). gc-ms method for the analysis of thirteen opioids, cocaine and cocaethylene in whole blood based on a modified quechers extraction. current pharmaceutical analysis, 13(3); 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(2018). application of gas chromatography–tandem mass spectrometry for the determination of amphetamine-type stimulants in blood and urine. journal of pharmaceutical and biomedical analysis, 148; 58–64 © 2023 the authors. page 460 of 460 introduction experimental section materials reagents and materials urine samples methods sample preparation method gc-ms results and discussion optimization of gc-ms conditions optimization of extraction method qualitative test of methamphetamine in urine samples by gc-ms validation method selectivity specificity linearity, detection limit, quantitation limit, and matrix effect accuracy and precision (intraday and interday) stability test carry over test application of m-quechers method for methamphetamine determination in the urine of abusers conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper spectrophotometric change of butterfly pea (clitoria ternatea l.) flower extract in various metal ion solutions during storage abdullah muzi marpaung1*, dania pustikarini1 1food technology department, swiss german university, the prominence tower jl. jalur sutera barat. no. 15, rt.003/rw.006, panunggangan tim., kec. pinang, tangerang, 15143, indonesia *corresponding author: abdullah.muzi@sgu.ac.id abstractthis study aimed to investigate the effect of six chloride salts on butterfly pea flower extract’s anthocyanins stability. the salts werenacl, kcl, cacl2, mgcl2, fecl3, and alcl3. the samples were analyzed using a uv-vis spectrophotometer to observe color degradationand change in hue during storage. the extraction of anthocyanins was done using a modified method, and the solutions were storedin dark vials at room temperature. the degradation kinetics of benzene derivatives, acyl groups, non-anthocyanin flavonoid, flavyliumcation, quinonoidal base and anionic quinonoidal base were evaluated using the first-order reaction, and the half-life was calculated.the effect of metal ions was studied by analyzing the change in absorbance of each band using regression analysis and a slopetest. the results showed that monovalent (na+ and k+) and divalent (ca2+ and mg2+) ions did not result in a significant shift in thespectrogram. trivalent metal ions (al3+ and fe3+) had limited interaction with the anthocyanins, heightened the brown color, anddecreased the overall color quality. k+, ca2+, mg2+, al3+, and fe3+ ions showed the ability to improve the stability of the extract’scolor, while na+ tended to accelerate color degradation. the pattern of changes in the spectrogram during storage suggests thatcolor degradation occurs in two ways: the unfolding of hydrophobic interactions and the deacylation of anthocyanin. trivalent metalions showed the best stability performance, with fe3+ preventing the unfolding of hydrophobic interactions and al3+ hindering thedeacylation. the combination of the two is highly likely to improve the color stability of the butterfly pea flower extract. however,both increase the browning index, thus decreasing color quality. this research highlights the potential of adding cations to improvethe color stability of the butterfly pea flower extract, making it a more attractive food coloring agent. keywordsanthocyanin, butterfly pea flower, color degradation, metal ions, stability, uv-vis spectrophotometer received: 12 february 2023, accepted: 10 may 2023 https://doi.org/10.26554/sti.2023.8.3.367-372 1. introduction the butterfly pea (clitoria ternatea l.) flower extract is a rich source of anthocyanins that are well-known for their deep purple-blue color and their stability in low acidic solutions (marpaung et al., 2017) . this relatively high stability is due to the presence of polyacylated anthocyanins in the butterfly pea flower extract, which has intramolecular copigmentation that helps to prevent the loss of color. the color of butterfly pea flowers can be used as food coloring, but further research is required to ensure the color remains stable. factors such as ph, chemical structure, light, heat, and metal ions can impact the stability of the color in butterfly pea flowers. previous studies have investigated the effect of metal ions on the stability of anthocyanins from different sources, with varying results. some studies have found that cations can improve anthocyanin stability, while others have found that they can provoke instability. for example, na+ has been found to decrease (de rosso and mercadante, 2007; hubbermann et al., 2006), improve (dangles and brouillard, 1992; figueiredo and pina, 1994; peng et al., 2016), or have no effect on anthocyanin stability (wang et al., 2010) . k+ increases the color intensity and improves stability (czibulya et al., 2015) , while others have found that ca2+ enhances color li (2014) without affecting stability (ren et al., 2014) , but in some cases, it decreases stability (ratanapoompinyo et al., 2017) . studies have observed no impact on anthocyanin color from mg2+ (sigurdson et al., 2016) . fe2+ and fe3+ enhance the color and stabilize the configuration of anthocyanins but also destroy anthocyanins (li, 2014; peng et al., 2016; ratanapoompinyo et al., 2017). al3+ has a positive effect on the stability of anthocyanins (maylinda et al., 2019; peng et al., 2016), while others have found no effect (li, 2014) . to date, there has been no study on the effect of metal ions https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.367-372&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.367-372 marpaung et. al. science and technology indonesia, 8 (2023) 367-372 on the stability of butterfly pea anthocyanins. therefore, the aim of this study is to investigate the impact of six different chloride salts (nacl, kcl, cacl2, mgcl2, fecl3, and alcl3) on the stability of butterfly pea flower extract anthocyanins. the uv-vis spectrophotometer would be employed to monitor the color degradation and change in hue of the extract during storage over a wavelength range of 250-700 nm. 2. experimental section 2.1 materials the study utilized fully opened flowers of butterfly pea (clitoria ternatea l.) sourced from a private plantation in tangerang, banten, indonesia. the petals were carefully separated from the sepals and steam-blanched for 6 minutes (marpaung et al., 2012) . various chemical reagents were utilized in the research, including aluminum chloride (analar bdh, england), calcium chloride (brataco, indonesia), (brataco, indonesia), iron (iii) chloride (eterna, indonesia), magnesium chloride (brataco, indonesia), potassium chloride (brataco, indonesia), and sodium chloride (analar bdh, england). 2.2 extraction and addition of metal ion the extraction of anthocyanins from butterfly pea (clitoria ternatea l.) flowers was conducted using a modified version of the previous research (marpaung et al., 2017) . the extraction process involved mixing 20 grams of the fresh petals with 80 milliliters of deionized water at 60ºc for 30 minutes in the absence of light and under constant agitation. the resulting suspension was then filtered (filter paper (whatman 41)), with the filtrate collected and centrifuged at 7,000 revolutions per minute for 5 minutes to separate the pigments. the chloride salts used in this study were nacl, kcl, cacl2, mgcl2, fecl3, and alcl3, and each had a concentration of 0.025 m. 0.6 ml of the salt solution was added to 1 ml of butterfly pea flower extract, while 0.6 ml of deionized water was added to the control solution. the sample of each extract (2 ml) was placed in a quartz cuvette and then scanned using a uv-vis spectrophotometer (genesys 10uv thermo electron corporation, u.s.a.) at a wavelength range of 250 700 nm with a 1 nm interval. 2.3 stability test each of the 20 ml sample was repeated twice and placed in a dark vial, then stored in a room that was kept away from light at room temperature. the spectrogram of each sample was scanned with the spectrophotometer at an interval of every two days. the changes in each band in the spectrogram were then analyzed. 2.4 kinetic formulation and statistical analysis the degradation kinetics of all the bands were evaluated by the first-order reaction. a = a◦.e −kt (1) t0.5 = ln(2)/k (2) a is the final absorbance, a◦ is the initial absorbance, k is the constant of degradation rate (per day), t is the storage time (in days), and t0.5 is the half-life (in days).the trend of the change in absorbance of each band was analyzed using regression analysis, with a significance level of 𝛼 = 0.05. the slope difference between two samples was assessed using a slope test. both statistical evaluations were conducted using microsoft excel® as part of microsoft 365, which was developed by microsoft in redmond, washington, usa, with a significance level of 𝛼 = 0.05. 3. results and discussion 3.1 the effect of the metal ions on the spectrogram six bands appeared in the spectrogram of the aqueous extract of the butterfly pea flower (figure 1a). the uv region featured three bands, representing benzene derivatives (at ± 265 nm), acyl groups (at ± 310 nm), and non-anthocyanin flavonoids (at ± 350 nm). the visible light region featured three bands of the colored species of anthocyanins, at ± 550 nm representing the red flavylium cation ah+, at ± 574 nm, representing the purple quinonoidal base a, and at ± 617 nm representing the blue anionic quinonoidal base a− (marpaung et al., 2019) . the addition of monovalent (na+ and k+) and divalent (ca2+ and mg2+) did not give a significant shift in the spectrogram of the extract (figure 2b). the absence of the shift caused by the addition of monovalent and divalent metal ions was also observed in various anthocyanin source extracts, such as blueberries (wang et al., 2010) , red cabbage (guo et al., 2017) , black peanuts (shao et al., 2015) , buniusantidesma (mustika and marpaung, 2020) , cyanidin-derived anthocyanin (sigurdson et al., 2017; sigurdson et al., 2016), ribes nigrum (buchweitz et al., 2013) , dark maize (mei et al., 2014) , and fungus pycnoporus sanguineus (zhang et al., 2019) . in contrast, sodium (na+) enhances the color of malvidin-derived anthocyanin (dangles and brouillard, 1992; figueiredo and pina, 1994), potassium (k+) increases the intensity of anthocyanin in red wine (czibulya et al., 2015) , and calcium (ca2+) has a color-enhancing effect on blueberry anthocyanin (li, 2014) and a slight impact on the color of red cabbage anthocyanin (ratanapoompinyo et al., 2017) . there was also limited evidence of interaction between trivalent metal ions (al3+ and fe3+) and the anthocyanins in the butterfly pea flower extract (figure 1c). the spectrogram of the butterfly pea flower extract added with al3+ showed only a minor increase in absorbance at ± 550 nm and a slight decrease at ± 617 nm, indicating a possible contribution of al3+ to the protonation reaction a− ⇌ a ⇌ ah+. a similar outcome was observed in extracts containing fe3+ ions. although there was a noticeable shift towards red in hue, it appears to be the same effect exhibited by al3+, where fe3+ drove the protonation. fe3+ had a more intense protonation effect than al3+. © 2023 the authors. page 368 of 372 marpaung et. al. science and technology indonesia, 8 (2023) 367-372 figure 1. uv-vis light spectra of butterfly pea flower aqueous extract (a), in divalent metal ion (b), and trivalent metal ion solution (c) aside from intensifying the red color, al3+ and fe3+ also heightened absorption at 420 nm, which reflects yellow-brown color. the average absorption at 420 nm (a420) in the extracts added with trivalent metal ions was ± 0.5, while in other extracts it was ± 0.06. the high a420 significantly increased the browning and decreased the overall color quality of the extract (cisse et al., 2012) . the reason why metal ions interact with anthocyanins is not known, but the case of butterfly pea flower extract provides a clear understanding. metal ions typically interact with anthocyanins via hydroxyl groups on the b-ring. however, the anthocyanins in butterfly pea flowers, the polyacylated anthocyanins known as ternatins, lack free hydroxyl groups on the b-ring (kazuma et al., 2003) . significant changes occurred in the uv region in the extract added with al3+, including a new band around 380 nm, which appears to be a shift to a longer wavelength from the 350 nm absorption, which is the absorbance of non-anthocyanin flavonoids. this new band indicates the formation of a complex between the non-anthocyanin flavonoid and al3+. flavonol glycosides are the most found flavonoids in butterfly pea flowers, with kaempferol 3-glycoside being the main compound (kazuma et al., 2003) . the interaction between kaempferol and al3+ has been reported recently (sun et al., 2021) . a significant shift to longer wavelengths was also observed in the uv region of the extract with fe3+, indicating the potential interaction between fe3+ and non-anthocyanin phenolic compounds. 3.2 the effect of the metal ions on the color stability during storage scanning of butterfly pea flower extract’s light absorption (250700 nm) during storage revealed changes in benzene derivatives, acyl groups, non-anthocyanin flavonoids, and anthocyanins over time (figure 2). overall, a degradation of color (a550 + a574 + a617) occurred in all extracts during the 12 days of storage. the rate of color degradation can be modeled by first-order degradation kinetics satisfactorily (p-value of the regression < 0.05). a slope test was carried out with an alpha level of 0.05 to assess the differences in degradation rate between the control extract and extracts containing various metal figure 2. uv-vis spectrogram of butterfly pea flower aqueous extract in various metal ion solutions during 12 days storage (a), control (b), na+ (c); k+, (d) ca2+, (e) mg2+, (f) al3+, and (g) fe3+ ions, as seen in table 1. the test indicated that k+, mg2+, ca2+, al3+ and fe3+ significantly prolonged the half-life of the flower extract’s color. meanwhile, na+ tended to shorten the half-life. table 1. the degradation kinetics (k) and half-life (t0.5) of the color of butterfly pea flower extract in various metal ion solution extract r2 p-value k (day-1)* t0.5 (days)* h2o 0.96 <0.01 0.068 10.23b nacl 0.88 <0.01 0.305 2.27a kcl 0.90 <0.01 0.039 17.72c cacl2 0.93 <0.01 0.030 23.20d mgcl2 0.79 <0.05 0.026 26.48d alcl3 0.80 <0.05 0.024 28.91d fecl3 0.80 <0.05 0.017 41.17e *stated as mean of two replications, different letters above data points indicate significant differences the effect of metal ions on anthocyanin stability is inconsistent, with some studies showing a negative effect of na+ (chen et al., 2019; de rosso and mercadante, 2007; hubbermann et al., 2006), while others show no effect (dangles and brouillard, 1992; figueiredo and pina, 1994; peng et al., 2016). the destabilization by na+ is thought to result from increased solvation of the flavylium cation, leading to dissociation and © 2023 the authors. page 369 of 372 marpaung et. al. science and technology indonesia, 8 (2023) 367-372 figure 3. two possible pathway of color degradation of a polyacylated anthocyanin like ternatin in butterfly pea flower extract, (a) the first way initiated by the unfolding of flavylium cation (ah+), (b) the second way initiated by the diacylation of anionic quinonoidal base (a−) color loss (hubbermann et al., 2006) . the positive effect of k+ has been reported (czibulya et al., 2015) , but differs from other findings (guo et al., 2017) . the positive effect of ca2+ observed in this study is consistent with czibulya et al. (2015) , but differs from other studies that saw no significant impact (buchweitz et al., 2013; guo et al., 2017). this study showed a significant positive impact from mg2+ on anthocyanin stability. meanwhile, other studies show that mg2+ give no effect (peng et al., 2016; sigurdson et al., 2016) or even decreased stability (mei et al., 2014) . peng et al. (2016) found a negative impact of fe3+ and a positive impact of al3+ on anthocyanin stability. the negative impact of fe3+ was also reported by guo et al. (2017) and ratanapoompinyo et al. (2017) . this study supports the improvement of stability by both trivalent metals. in the aqueous system, polyacylated anthocyanins such as ternatins exist in a state of equilibrium between red, purple, and blue species: ah+ ⇌ a ⇌ a−. the hydration of ah+ into the colorless hemiketal b does not occur because it is prevented by the intramolecular copigmentation that forms through the hydrophobic interaction between p-coumaric acid and the anthocyanin molecule (terahara et al., 1998) . theoretically, two pathways can cause a polyacylated anthocyanin to lose its color, as depicted in the scheme in figure 3 (marpaung et al., 2017; marpaung et al., 2019). in the first pathway, the hydrophobic interaction in ah+ undergoes unfolding, causing ah+ to hydrate into b. this reaction disrupts the equilibrium of ah+ ⇌ a ⇌ a− and drives protonation of a → ah+ and a− → a to reach a new equilibrium (figure 3a). in the second pathway, a− as the least stable species terahara et al. (1998) is deacylated to a−unacylated, then deprotonated to aunacylated, and then ah+unacylated, which immediately hydrated to bunacylated. this series of reactions disrupt the equilibrium of ah+ ⇌ a ⇌ a− (polyacylated) leading to deprotonation a → a− and ah+ → a (figure 3b). in the next stage, after the loss of color in anthocyanin, degradation continues to de-glycosylation to anthocyanidin and further degradation to benzaldehyde derivatives and 4-hydroxybenzoic acid (sun et al., 2011) . the first event of the color loss can be observed in the spectrogram as a hypochromic shift and the constant or increasing concentration of ah+ relative to a (a550/a574) and the ratio of a− to a (a574/a620). meanwhile, the second event can be observed as a hypochromic and bathochromic shift, as well as a decrease in a574/a620 and a550/a574. the extract added with al3+ was the only sample that consistently shows an increase in a550/a574 and a574/a620. conversely, the extract added with fe3+ consistently showed a decrease in a550/a574 and a574/a620, although the bathochromic shift was not clearly visible. meanwhile, in the control sample and those added with monovalent or divalent ions, there was an increase in a550/a574 and a574/a620 at the beginning of degradation, followed by a decrease in both ratios in the subsequent degradation stage. as an addition, a clear bathochromic shift is also seen in the control extract and those added with na+, k+, and mg2+ (figure 2a, 2b, 2c, and 2e).the trend of changes in both ratios suggested that color degradation in the extract added with al3+ occurred due to the unfolding of hydrophobic interaction, while in the extract added with fe3+ the color degradation occurred due to deacylation. meanwhile, color degradation in the control sample and those added with monovalent and divalent metal ions occurred due to the unfolding of hydrophobic interaction and followed by deacylation. 3.3 the effect of the metal ions on benzene derivatives, acyl groups, non-anthocyanin flavonoids the light absorption at 265 nm (a265) represents benzene derivatives, including anthocyanins and other flavonoids. figures 2 clearly shows that the addition of trivalent metal ions inhibited the degradation of benzene derivatives. with a firstorder degradation kinetics model (p-value), the degradation rate (k) of a265 in the extract added with al3+ or fe3+ was significantly lower compared to the k in other extracts. in line with the degradation of colored anthocyanins, the stability of benzene derivatives in the extract added with na+ was lower compared to the control extract. however, there was no significant difference in the stability of benzene derivatives between the control extract and those added with k+, ca2+, and mg2+. the evolution of light absorption at 310 nm (a310), which represents the acyl group, offered compelling evidence in support of the hypothesis regarding the mechanisms of anthocyanin degradation. the exponential regression analysis (1st order degradation kinetics) revealed that degradation of a310 in the extract added with al3+ was the only one that was not statistically significant (p > 0.05). this supported the notion that deacylation did not occur in the extract containing al3+, thereby reinforcing the idea that the degradation of colored anthocyanins in this sample was a result of the unfolding of hydrophobic interaction. the fact that degradation of a310 was not significant and the degradation rate of a265 in the extract containing al3+ was low suggests that the color degradation in this extract has only © 2023 the authors. page 370 of 372 marpaung et. al. science and technology indonesia, 8 (2023) 367-372 reached the stage of transforming colored ternatin species into a reversible colorless one. there had not been any chemical degradation of the ternatins to unacylated anthocyanin and further to anthocyanidin, etc. the extract added with al3+ is also the only sample that did not experience significant degradation of non-anthocyanin flavonoids (a350 and a380). it seemed that al3+ successfully formed a stable complex with the non-anthocyanin flavonoids in the butterfly pea extract. whether there is a connection between the stability of this complex and the inhibition of deacylation in butterfly pea flower anthocyanin, further study is needed. 4. conclusion scanning the uv-vis spectrophotometer at the wavelength range of 250-700 nm on the butterfly pea flower extract in various metal ion solutions during storage has provided a broader perspective on how color degradation occurs. k+, ca2+, mg2+, al3+, and fe3+ ions showed the ability to improve the stability of the butterfly pea flower extract color, while na+ tended to accelerate color degradation. the pattern of changes in the extract spectrogram during storage suggests that the color degradation of the extract proceeds through two mechanisms: the unfolding of hydrophobic interactions that establish the intramolecular copigmentation between ternatin and p-coumaric acid, and the deacylation of ternatin. trivalent metal ions showed the best stability performance. fe3+ prevented the unfolding of the hydrophobic interaction, while al3+ hindered the occurrence of deacylation. the combination of the two is highly likely to improve the color stability of the butterfly pea flower extract. however, both increase the browning index, thus decreasing color quality. this research highlights that the addition of cations is a potential method for improving the color stability of the butterfly pea flower extract, making it a more attractive food coloring agent. 5. acknowledgment the authors would like to express their gratitude to the faculty of life sciences and technology at swiss german university for providing the necessary laboratory facilities to conduct this research. we greatly appreciate the support and resources provided by the faculty, which enabled us to carry out our experiments and collect valuable data. references 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experimental section materials extraction and addition of metal ion stability test kinetic formulation and statistical analysis results and discussion the effect of the metal ions on the spectrogram the effect of the metal ions on the color stability during storage the effect of the metal ions on benzene derivatives, acyl groups, non-anthocyanin flavonoids conclusion acknowledgment research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 1 (2018) 49-52 © 2018 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 1 december 2017; revised 11 january 2018; accepted 11 january 2018 http://doi.org/10.26554/sti.2018.3.1.49-52 the definite positive property of characteristic function from compound geometric distribution as the sum of gamma distribution darvi mailisa putri1, maiyastri2, and dodi devianto3* 1,2,3department of mathematics, faculty of mathematics and natural sciences, andalas univerrsity, padang 25163, west sumatra province, indonesia *corresponding author e-mail: ddevianto@fmipa.unand.ac.id abstract in this expository article it is given characterization of compound geometric distribution as the sum of gamma distribution. the characterization of this compound distribution is obtained by using the property of characteristic function as the fourier-stieltjes transform. the property of definite positive of characteristice function from compound geometric distribution as the sum of gamma distribution is exposed by analytical methods as the quadratic form of characteristic function. keyword: compound geometric distribution, gamma distribution, characteristic function, definite positive. 1. introduction let us define s as the sum of independent and identically random variables, that is in the form s = x i i=1 n ∑ (1.1.) where the number of random variable xi , that is n, itself a random variable. the property of this random variable has been paid great attention to many years. the most popular terminology for the distribution generated by such as a sum of random variables is called compound distribution. compound distributions arise from many applied probability models and from insurance risk models in particular. one of the compound distributions that attracted the researcher was the compound geometric distribution. the compound geometric distribution, as a special case of the compound negative binomial distribution plays a vital role in analysis of ruin probabilities and related problems in risk theory and insurance as in willmot and lin (2001). the most recently theoretical approach of compound geometric distribution has started by introducing on higher-order properties of compound geometric distributions (willmot, 2002), this development is continued on the study of convolutions of compound geometric distributions (psarrakos, 2009). furthermore, it has reviewed convolution on generated random variable from exponential distribution with stabilizer constant (devianto et. al, 2015; devianto, 2016) and some properties of hypoexponential distribution with stabilizer constant (devianto et. al, 2015). while in the last development of compound geometric distribution was delivered by koutras and erylmaz (2016) when they studied compound geometric distributions of order k . in the present paper, we study the property of compound geometric distribution as the sum of gamma distribution. it will be discussed characterization of compound geometric distribution as the sum of gamma distribution in the form of definite positive property of characteristic function. in section 2, we will explain about characterization of gamma distribution and compound geometric distribution. while the some properties of compound geometric distribution as the sum of gamma distribution will be given in section 3. 2. the characterization of gamma distribution and compound geometric distribution the gamma distribution is a family of continuous probability distribution with parameter α dan β. let x be a random variable from gamma distribution with the form f(x)= 1 βαγ(α) xα−1exp[− xβ ] (2.1.) for 0>x , α > 0, and β > 0. the expectation and variance of gamma distribution are given by e(x)=αβ (2.2) putri et al. 2018 / science & technology indonesia 3 (1) 2018: 49-52 50 var(x)=αβ2 (2.3) as for the moment generating function and characteristic function of the gamma distribution we can obtain by using definition of fourier-stieltjes transform refers to lukacs (2009) in the following m x (t)= e[exp(tx)]= 1 1− βt ⎛ ⎝⎜ ⎞ ⎠⎟ α (2.4) φ x (t)= e[exp(itx)]= 1 1− βit ⎛ ⎝⎜ ⎞ ⎠⎟ α (2.5) the figure 1 is the graph of parametric curves of characteristic function from gamma distribution with various parameter α. while the figure 2 is the graph of parametric curves of characteristic function from gamma distribution with various parameter β. the graph of these parametric curves of characteristic function are described in the complex plane that shows a smooth line, this is to confirm that its characteristic function is continuous and never vanish on the complex plane. the compound geometric distribution is the sum of independent and identically random variable, where the number of random variables has geometric distribution as follows p(n = n)= p(1− p)n (2.6) for ...,2,1,0=n and 10 << p , p is the probability of success. the geometric distribution has expectation and variance as follows e(n)= 1− p p (2.7) var(n)= 1− p p2 (2.8) by using similar way with equation (2.4) and (2.5), we have the moment generating function and characteristic function of the geometric distribution respectively as follows m n (t)= 1 1−(1− p)exp[t] (2.9) m n (t)= p 1−(1− p)exp[it] (2.10) the figure 3 is the graph of parametric curves of characteristic function from geometric distribution with various parameter p. the graph of its characteristic function is described in the complex plane that shows a smooth line, this is also to confirm that this characteristic function is continuous and never vanish on the complex plane. 3. the some properties of compound geometric distribution as the sum of gamma distribution the property of compound geometric distribution as the sum of gamma distribution will be stated on its definite positive of characteristic function. in order of the main result in this section, it is explained the property definite positive of characteristic function in proposition 3.4, at the first we introduce the moment generating function, characteristic function and continuity property at the following propositions. proposition 3.1. let the random variable s = xi i=1 n ∑ is defined as a compound geometric distribution as the sum of gamma distribution with parameter (p,α ,β ), then moment generating function is obtained as follows m s (t)= p 1−(1− p)(1− βt)−α (3.1) proof. by using definition of conditional expectation and its linearity property then it is obtained the moment generating function as follows m s (t)= e exp t x i i=1 n ∑ ⎛ ⎝⎜ ⎞ ⎠⎟ ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ = e e exp t xi i=1 n ∑ ⎛ ⎝⎜ ⎞ ⎠⎟ n ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ (3.2) 001.0 005.0 009.0 5 15 30 1.0p 5.0p 9.0p 35.0p 65.0p 95.0p figure 4. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 9.0,7.0,5.0 where 009.0 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 1. parametric curves of characteristic function from gamma distribution with various parameters α = 0.5, 0.7, 0.9 001.0 005.0 009.0 5 15 30 1.0p 5.0p 9.0p 35.0p 65.0p 95.0p figure 4. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 9.0,7.0,5.0 where 009.0 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 2. parametric curves of characteristic function from gamma distribution with various parameters β = 0.5, 0.7, 0.9 001.0 005.0 009.0 5 15 30 1.0p 5.0p 9.0p 35.0p 65.0p 95.0p figure 4. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 9.0,7.0,5.0 where 009.0 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 3. parametric curves of characteristic function from geometric distribution with various parameters p = 0.1, 0.5, 0.9 putri et al. 2018 / science & technology indonesia 3 (1) 2018: 49-52 51 now, let us use the definition of moment generating function then we have m s (t)= e(m x (t)n )= m n (ln(m x (t))) (3.3) base on the equation (2.4) and (2.9) and we substitute to equation (3.3), then we have ( )( ) . 111 )( ab ---= tp p tms proposition 3.2. let the random variable is defined as a compound geometric distribution as the sum of gamma distribution with parameter , then ),,( bap characteristic function is obtained as follows ( )( ) . 111 )( ab f ---= itp p ts (3.4) proof. by using definition of conditional expectation and its linearity property then we can write the characteristic function as follows ÷ ÷ ø ö ç ç è æ ÷ ÷ ø ö ç ç è æ ÷÷ ø ö çç è æ =÷ ÷ ø ö ç ç è æ ÷÷ ø ö çç è æ = åå == nxiteexitet n i i n i is 11 expexp)(f (3.5) now, let us use the definition of moment generating function and definition of characteristic function to write )))((ln())(()( tmtet xn n xs fff == (3.6) base on the equation (2.4) and (2.5) then we have ( )( ) . 111 )( ab f ---= itp p ts proposition 3.3. let the random variable å = = n i ixs 1 is defined as a compound geometric distribution as the sum of gamma distribution with parameter ),,( bap and characteristic function ( )( ) ,)( ab f ---= itp p ts 111 then )(tsf is continuous. proof. the continuity property is explained by using definition of uniform continuity, that is for every 0>e there exists 0>d such that eff <)()( 21 tt ss for d<21 tt where d depends only on e . then the uniform continuity of characteristic function is obtained by the following way. first we write the following equation ( )( ) ( )( ) ( ) ( ) . )(11 1 )(11 1 111111 )()( 21 21 21 tptp p itp p itp p tt xx ss ff bb ff aa --= ----=-(3.7) now let us define 21 tth -= , so that for 0®h we have the following limit .0 )()1(1 1 )()1(1 1 220 = -+--® tpthp lim xxh ff (3.8) this hold for ed < where eff <-+ )()( 22 tth ss for d<21 tt . then )(tsf is uniformly continuous. proposition 3.4. let the random variable s = x i i=1 n ∑ is defined as a compound geometric distribution as the sum of gamma distribution with parameter (p, α , β ) and characteristic function ( )( ) ,)( ab f ---= itp p ts 111 then fs(t) is positively defined function with quadratic form 0)( 1 1 ³-å å ££ ££nj ljxlj nl ttcc f (3.9) for any complex number nccc ...,,, 21 and real number nttt ...,,, 21 . proof. we will show the characteristic function )(tsf is positive function that is to satisfy the quadratic form 0)( 1 1 ³-å å ££ ££nj ljxlj nl ttcc f for any complex numbers nccc ...,,, 21 and real numbers nttt ...,,, 21 . it is used definition of characteristic function of compound geometric distribution as the sum of gamma distribution and a geometric series with ratio (1 p)e(exp(i(tj-tl)x) where p ∈(0.1) and 1))(((exp £xttie lj , hence we have the following equation ( ) å åå å å å åå å ££ ¥ =££ ££ ££ ££ ££££ ££ ÷÷ ø ö çç è æ --= --= ---=nj m m ljlj nl nj lj lj nl nj lj lj nlnlj ljslj nl xttiepccp xttiep p cc ttip p ccttcc 1 01 1 1 1 1,1 1 ))(((exp)1( )))(((exp)1(1 )(1)1(1 )( ab f (3.10) 001.0 005.0 009.0 5 15 30 1.0p 5.0p 9.0p 35.0p 65.0p 95.0p figure 4. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 9.0,7.0,5.0 where 009.0 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 0.2 0.4 0.6 0.8 1.0 0.6 0.4 0.2 0.2 0.4 0.6 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 1.0 0.5 0.5 1.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 4. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters α = 0.5, 0.7, 0.9 where β = 0.009 putri et al. 2018 / science & technology indonesia 3 (1) 2018: 49-52 52 we rewrite the equation (3.10) by using its complex conjugate property and exponential function property as the follows ÷ ÷ ø ö ç ç è æ ÷÷ ø ö çç è æ -´ ÷ ÷ ø ö ç ç è æ ÷÷ ø ö çç è æ -= ååå å å å ¥ =££££ ¥ = ££ ££ m m ll nlnj m m jj nlj ljslj nl xtiepcxtiepcp ttcc 011 0 ,1 1 )((exp)1()((exp)1( )(f (3.11) next, base on the quadratic form property of modulus complex number, then we obtain ( ) 01)1( )((exp)1()( 2 1 0 2 1 0,1 1 ³÷÷ ø ö çç è æ --= ÷÷ ø ö çç è æ -=å å å åå å ££ ¥ = ££ ¥ =££ ££ nj m m jj nj m m jj nlj ljslj nl itpcp xtiepcpttcc ab f (3.12) then it is proved that fs (t) as positively defined function where the quadratic form has nonnegative values. the graph of parametric curves of characteristic function from compound geometric distribution as the sum of gamma distribution will be presented in figure 4, figure 5, and figure 6 as follows based on the graph presented in figures 4, 5, and 6, it can be concluded that the characteristic function of compound geometric distribution as the sum of gamma distribution is continuous, as well as it has discussed on proposition 3.3 . in figure 4 and 6, the shape of parametric curves form three smooth lines. while in figure 5 the shape of parametric curves only form the same smooth line for various parameter β, and tends to be one for all various parameter α dan β when fixed on parameter p. 4. conclusion the compound geometric distribution as the sum of gamma distribution is the sum of independent and identically random variable from gamma distribution, where the number of these random variables has geometric distribution. the characterization of compound geometric distribution as the sum of gamma distribution is obtained by using the property of characteristic function, where the characteristic function is defined as the forier-stieltjes transform. the property of definite positive of characteristice function from compound geometric distribution as the sum of gamma distribution is exposed by showing its quadratic form of characteristic function. the addition property of this compound geometric distribution as the sum of gamma distribution is coninuity peroperty of characteristic function, where the graph of the parametric curves of characteristic function is in the smooth line and never vanish on the complex plane. references devianto, d., (2016). the uniform continuity of characteristic function from convoluted exponential distribution with stabilizer constant. aip conference proceedings, american institute of physics. devianto, d., maiyastri, oktasari, l. & anas, m. (2015). convolution on generated random variable from exponential distribution with stabilizer constant. applied mathematical sciences, 9(96), 4781-4789. devianto, d., oktasari, l., & maiyastri. (2015). some properties of hypoexponential distribution with stabilizer constant. applied mathematical sciences, 9(142), 7063-7070. koutras, m.v., & eryilmaz, s. (2016). compound geometric distribution of order k. methodol. comput. appl. proba, 19(2), 377-393. lukacs, e. (1970). characteristic function (2nd edition). london: griffin. psarrakos, g. (2009). a note on convolutions of compound geometric distributions. statistics & probability letters, 79(9), 1231-1237. willmot, g.e. (2002). on higher-order properties of compound geometric distributions. applied probability, 39(2), 324-340. willmot, g.e., & lin, x.s. (2001). lunberg approximations for compound distributions with insurance applications. new york, ny: springer. 5.0 7.0 9.0 figure 5. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 09.0,07.0,05.0 where 5.0p 5.0 7.0 9.0 figure 6. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 95.0,65.0,35.0p where 7.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 5. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters β = 0.05, 0.07, 0.09 where p = 0.5 5.0 7.0 9.0 figure 5. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 09.0,07.0,05.0 where 5.0p 5.0 7.0 9.0 figure 6. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution with various parameters 95.0,65.0,35.0p where 7.0 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 0.2 0.4 0.6 0.8 1.0 0.4 0.2 0.2 0.4 figure 6. parametric curves of characteristic function from compound geometric distribution as thesum of gamma distribution science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 1-8 article http://sciencetechindonesia.com @2017 published under the terms of the cc by nc sa 4.0 license 1 preparation of polyoxometalate compound (nh4)6(β-p2w18o62)/sio2 by sol-gel method and its characterization osin r tambunan1*, risfidian mohadi1 1department of chemistry, faculty of mathematic and natural science, univeristas sriwijaya. jl. palembang prabumulih, km. 32, indralaya, ogan ilir, sumatera selatan *corresponding author e-mail : osintambunan@yahoo.com abstract preparation of polyoxometalate compound of (nh4)6(β-p2w18o62)nh2o supported with silica derived from the hydrolysis of tetraethyl orthosilicate by sol-gel method has been conducted. the compound was synthesized and characterized using ft-ir spectrophotometer, crystallinity using xrd analysis and the determination of acidity via quantitatively and qualitatively. qualitative analysis was performed using ammonia and pyridine adsorption and quantitative analysis using potentiometric titration. ft-ir spectrum of (nh4)6(β-p2w18o62)nh2o appeared in wavenumber 786.96 cm-1 (w-oc-w), 918.12 cm-1 (w-oe-w), 964.41 cm-1 (w=o), 1087.85 cm-1 (p-o), 3572.17 cm-1 (o-h), 1404.18 cm-1 (n-h) reinforced with wavenumber 1612.49 cm-1 with show vibration nh dari nh+, and to (nh4)6(β-p2w18o62)nh2o/sio2 appears in wavenumbers 794.67 cm-1 (w-oc-w), 918.12 cm-1 (w-oe-w), 1049.28 cm-1 (w=o), 1087.85 cm-1 (p-o), 3564.15 cm-1 (o-h), 470.63 cm-1 (si-o). diffraction pattern of (nh4)6(β-p2w18o62)nh2o and (nh4)6(β-p2w18o62)nh2o/sio2 compound show high crystanillity. the acidic properties showed (nh4)6(βp2w18o62)nh2o/sio2 more acidic than (nh4)6(β-p2w18o62)nh2o. analysis of the effect of temperature on the stability of the compounds polyoxometalate (nh4)6(β-p2w18o62)nh2o/sio2 show that the temperature of 600ºc the shift in wavenumbers of the compounds caused by vibration w=o, w-oc-w, w-oe-w has been lost. this shows that at a temperatures of 600ºc on heating can cause changes in the structure of polyoxometalate (nh4)6(β-p2w18o62)nh2o/sio2. keywords : (nh4)6(β-p2w18o62).nh2o, polyoxometalate, sio2 introduction polyoxometalate is a metal-oxygen cluster compound having acid-base properties, has various structural variations and oxidation rates so it is very effective for both acid base and oxidation reaction catalyst. in general, polyoxometalate compounds can be classified into two groups: isopolyoxometalate and heteropolioxometale (yamase et al, 2002). polyoxometalate compounds have many benefits, as a catalyst and basic ingredients of macromolecular synthesis. its utilization as a catalyst because it has a high acidity that exceeds sulfuric acid and is not toxic (okuhara et al,1996). research on polyoxometalate compounds is primarily intended in terms of its superiority as a catalyst which can be performed in homogeneous and heterogeneous system depending on the medium used. in heterogeneous system, polyoxometalate compounds may be used repeatadly of catalytic reaction. polyoxometalate compounds have attracted attention to continue to be developed due to flexible properties as acid and base as well as an adjustable oxidation rate according to the desired application recruitments (kozhevnikov, 2002). previous research has been done on the development of polyoxometalate compounds using carriers as tio2, zrocl2, tacl5 (fatimah, 2009). yang (2011) has also carried on article history received: 23 september 2016 accepted: 3 november 2016 doi: 10.26554/sti.2017.2.1.1-8 (nh4)6(β-p2w18o62).nh2o with sio2 sourced from tetraethyl orthosilica (teos) and using alcohol as a medium. in his research, teos hydrolys was used as a source of sio2 by using microemulsion medium derived from sodium bis(2-ethylhexsil) sulfosuccinate with cyclohexane (kim et al, 2006). according to eriksson et al (2004) miccroemulsion is a liquid derived from a mixture of water, hydrocarbons, and surfactants. sari and situngkir (2016) reported metal oxide from reduction of teos (tetra ethyl ortho silicate) supported polyoxometalate. polyoxometalate compounds embedded with sio2 using microemulsions and sol-gel techniques are expected to have characteristics as catalysts having uniform pore sizes and can improve the acidity side of polyoxometalate compounds. in this research, synthesis and characterization of dawson-type polyoxometalate compound (nh4)6(β-p2w18o62) were carried out with sio2. the process of loading is done by sol-gel technique. to know the functional groups of polyoxometalate compound and to know whether or not a sio2 carried by polyoxometalate compounds is characterized using ft-ir spectrofotometr and xrd. this characterization is perfomed both before and after the silica is carried by the polyoxometalate compounds. the acidity of the compound (nh4)6(βp2w18o62).nh2o/sio2 was studied through quantitative and qualitative studies through potentiometric titration and identification using an ft-ir spectrometer followed by thermal stability test. experimental section the xrd shimidzu lab x type 6000, spectofotometer ftir shimidzu prestige 21 were used for characterizatio of the tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 2 polyoxometalate compounds in this research. the materials used in this research were sodium tungsten, ortho phosphoric acid, aquades, ammonia, ammonium chloride, tetraethyl orthosilicals, bis(2-ethylhexsil)sulfosuccinate, n-butilamin, pyridin, cyxlohex-ane and acetonitrile. synthesis of dawson-type polyoxometalate compounds (nh4)6(β-p2w18o62).nh2o and its characteritation. a total amount of 31.25 g of sodium tungsten was dissolved in water 62.5 ml and added 26.25 ml ortho phosphoric acid while stirred with a magnetic stirrer.the obtained solution was refluxed for 4 hoursand obtained a greenish solution. the solution was cooled and added 12.5 g ammonium chloride while stirring for 10 minutes to obtain a pale yellow solid. the obtainedsolid was filtered, dissolved with 75 ml aquades and the obtain filtrate was added with 12.5 g ammonium chloride to obtain a white solid. the white solid was filtered and dissolved with 31.25 ml of distilled water. the obtained solution was left for 5 days for polyoxometalate compound (nh4)6(βp2w18o62).nh2o according to (contant, 1990). the polyoxometalate (nh4)6(β-p2w18o62).nh2o obtained is characterizes by spectrophotometer ft-ir and xrd. preparation polyoxometalate compounds (nh4)6(βp2w18o62).nh2o/sio2 by sol-gel method (newman et al, 2006) preparation polyoxometalate compound (nh4)6(βp2w18o62).nh2o/sio2 was modified from the kim et al (2006) procedure. the compound (nh4)6(β-p2w18o62).nh2o/sio2 was synthesized with 0.5 g sodium bis(2-ethylhexyl) sulfosuccinate dissolved with 1 ml siclohexane (solution a). compound (nh4)6(β-p2w18o62).nh2o of 0.76 g was dissolved with 1 ml of aquadest ( solution b).solution b was added to solution a while distirer. a total 2 ml tetraethyl ortosilica (teos) was added dropwise. stirred with a magnetic stirrer and heated 60°c. the mixture will form a hydrogel ang heated to 100°c while stirring with a glass spatula. the white solid formed is a compound. (nh4)6(β-p2w18o62).nh2o/sio2. the compound (nh4)6(β-p2w18o62).nh2o/sio2 was characterized by a ft-ir spectrofotometer, and an xrd diffractometer. acidity test of the compound (nh4)6[βp2w18o62].nh2o/sio2 qualitatively the acidity test was qualitatively modified from the maksimov et al (2001) procedure by saturation of polyoxometalic compounds using ammonia and also pyridine. for saturation with ammonia as much as 0.5 g of compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/ sio2 inserted into vials and 1 ml of ammonia (nh3) 25% into a beaker. a vial bottle is inserted into a beaker containing ammonia and tightly sealed with a plastic kreb. the compound is allowed one day in order to adsorption between ammonia and polyoxometalic compound. for saturation using a pyridine compound, the same work was done. a total of 0.5 g of each compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62) .nh2o/sio2 were inserted into vials and 1 ml of pyridine 25% were fed into beaker. a vial bottle is inserted into a beaker containing ammonia and tightly sealed with a plastic kreb. the compound was allowed for one day to allow adsorption between pyridine and polyoxometalate compounds. compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/ sio2 results in saturation with ammonia and pyridine were qualitatively tested by characterization using a ft-ir spectrophotometer. acidity test of the compound (nh4)6(βp2w18o62).nh2o/sio2 quantitatively (reddy et al, 2006) a total of 0.1 g of each compound (nh4)6(βp2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2 were dissolved in 8 ml acetonitrile and stirred for 6 hours with a magnetic stirrer. the suspension was titrated with 0.05 m nbutylamine which was monitored by glass electrode as a ph sensor. each droplet of potential titrant pervolume was generated, and recorded and linked potentiometric titration curves between the titrant volume and the resulting potential. the classification of the seams from the acidity side was classified on a scale: e> 100 mv (very acidic); 0> e> 100 mv (acid side); -100 <e <0 mv (weak acid side); and e <-100 mv (acid side is very weak). the impact of temperature on the stability of the compound (nh4)6(β-p2w18o62).nh2o/sio2 the compound (nh4)(β-p2w18o62).nh2o/sio2 was heated at various temperature 200oc, 300oc, 400oc, 500oc, and 600oc for 3 hours in he furnance. the combustion compound was cooled and analyzed by using ft-ir spectrofotometer. results and discussion synthesis of dawson-type polyoxometalate compound (nh4)6(β-p2w18o62).nh2o and characterization the synthesis of dawson type polyoxometalate compound (nh4)6(β-p2w18o62).nh2o based on the procedure performed by contant (1990) using sodium tungsten as the base material. the forming polyoxometalate compound were characterized by functional group analysis using a ft-ir spectrophotometer and christanility analysis using xrd analysis. the reaction of polyoxometalate compound formation as follows: 18(wo4)2+ 32h3po4 + 6(nh4)+  (nh4)6(β-p2w18o62) + 18h2o + 30h2po4 the identification was carried out on a polyoxometalate (nh4)6(β-p2w18o62).nh2o compound using a ft-ir spectrophotometer in the range of 200-4000 cm-1 wave numbers is shown in figure 1. the spectrum ft-ir polyoxometalate (nh4)6(β-p2w18o62).nh2o in figure 1 shows some significant absorption bands located at the wave number of 786 cm-1 showing the vibration of the w-oc-w group (oxygen in the middle of the polyoxometalic compound) and the numbers in 918 cm-1 denote the vibration of the w-oc-w group (the oxygen at the edge of the polyoxometalate compound). the wave number at 964 cm-1 shows the vibration of the w = o group, and the wave number at 1087 cm-1 denotes the vibration of the p-o group. the wave number at 1404 cm-1 denotes the vibration of the n-h group which is amplified by the 1612 cm-1 number indicating the nh vibration nh4+ (finke et al, 1987). the compound (nh4)6(β-p2w18o62).nh2o was analyzed using tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 3 xrd. diffractogram of compound (nh4)6(β-p2w18o62).nh2o. presented in figure 2. figure 1. ft-ir spectra polyoxometalate compound (nh4)6 (β-p2w18o62).nh2o figure 2. xrd diffraction pattern of polyoxometalate compound (nh4)6(β-p2w18o62).nh2o the diffractogram in figure. 2 shows the diffraction for the highest intensity of the polyoxometalate compound (nh4)6(βp2w18o62).nh2o complexes appearing at the diffraction angles of 8°, 17°, 27°. according to yang et al (2011) the diffraction for polyoxometalate compounds was found in some diffraction regions at 6-10°, 15-20°, 22-25°, and 35-40°. the diffraction that appears below 10° in region 2θ shows that the polyoxometalate compound has a very high crystallinity. diffractogram of polyoxometalate compound (nh4)6(β-p2w18o62).nh2o shows the sharp diffraction peaks indicating polyoxometalate (nh4)6(β-p2w18o62).nh2o compounds have very high crystalline properties in which the atoms of the polyoxometalic compound (nh4)6(β-p2w18o62).nh2o is arranged regularly based on the length and angle of the regular bond. synthesis of dawson-type polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2 and characteritation. the preparation of dawsontype polyoxometalate compound (nh4)6(β-p2w18o62).nh2o with sio2 based on the procedure undertaken by newman et al. (2006) in sio2 is derived from tetraethyl orthosilicate in the form of a liquid. identification using spectrophotometer ft-ir compound (nh4)6(β-p2w18o62).nh2o/sio2 showed the presence of specific vibrations of polyoxometalate and sio2 compounds presented in figure 3. on ft-ir spectrum of compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/ sio2 noticeable differences before placement and after assuming sio2. figure. 3 shows the difference shown by ft-ir spectrum of polyoxometalate (nh4)6(β-p2w18o62).nh2o compound before being assumed with sio2. according to derick et al, (1999) the asymmetric stretching vibration of si-o-si is at the wave number 1130-1000 cm-1. smith (1999) reported that the si-o-si asymmetric stretch vibration was stronger at 1085 cm-1. the ftir spectrum of compound (nh4)6(β-p2w18o62).nh2o/sio2 undergoes a shift of wave numbers for asymmetric si-o-si stretching vibration at 1103.28 cm-1. the shift of wave numbers occurs in vibration w = o. the w = o vibe before embodiment appears at 964.41 cm-1 wave numbers and the vibrations after being assumed with sio2 appear at 1049.28 cm-1 wave numbers. according to stuart (2004), the vibration -oh vibration in the presence of hydrogen bonding effect is in the range of 35002500 cm-1 wavelengths characterized by a widened peak on the ft-ir spectrum. figure 3b has a shift of wave numbers at the peak 3572.17 cm-1 identifies the -oh vibration by the presence of h2o in the compound (nh4)6(β-p2w18o62).nh2o and the wave number at peak 3464.15 cm-1 identifies the -oh by the presence of h2o in the compound (nh4)6(βp2w18o62).nh2o/sio2 figure 3. ftir spectrum of polyoxometalate (nh4)6(βp2w18o62).nh2o (a), (nh4)6(β-p2w18o62).nh2o/sio2 (b) figure 3a shows the spectra that appear at the wave numbers 786, 918, 964, 1087, 1404 cm-1 for vibration of the w-oc-w group (oxygen in the middle of the polyoxometalate compound), the vibration of the w-oe-w group (the oxygen at the edges of the polyoxometalic compound), the vibration of the w = o group, the vibration of the po group and the vibration of the nh group reinforced by the 1612 cm-1 indicate the nh vibration of nh4 (finke et al. 1987). in figure 3b the ft-ir sio2 spectrum of the absorption band peak appears at wave number 470 for the vibration of the si-o group. figure 3a spectra of ft-ir compound (nh4)6(β-p2w18o62).nh2o/sio2 tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 4 have the same absorption bands of both the polyoxometalate (nh4)6(βp2w18o62).nh2o as well as the sio2 absorption bands. this identifies the presence of polyoxometalate (nh4)6(β-p2w18o62).nh2o and sio2 forming groups which show the success of sio2 baffling process in the polyoxometalate (nh4)6(β-p2w18o62).nh2o. table 1 shows wave numbers of polyoxometalate compound (nh4)6(βp2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2. further, polyoxometalate (nh4)6(β-p2w18o62).nh2o analysis using xrd. comparison of the compound (nh4)6(βp2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2 presented in the figure 4. table 1. wave numbers of polyoxometalate compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/ sio2 (nh4)6(βp2w18o62).nh2o. (nh4)6(βp2w18o62).nh2o/sio2 vibration type 964.41 1049.28 w=o 786.96 794.67 w-oc-w 918.12 918.12 w-oe-w 1087.85 1087.85 p-o 3572.12 3464.15 o-h figure 4. difractions of (nh4)6(β-p2w18o62).nh2o (a) and (nh4)6(β-p2w18o62).nh2o/sio2 (b) polyoxometalate compound (nh4)6(β-p2w18o62).nh2o which was assumed by sio2 was characterized using xrd. characterization using xrd diffraction angle and crystallinity showed polioksometalate compounds dengan sio2 (nh4)6(βp2w18o62).nh2o/sio2. the comparison of xrd difraction of the compound (nh4)6(β-p2w18o62).nh2o with (nh4)6(βp2w18o62).nh2o/sio2 were presented in figure 4. figure 4a shows the diffraction of (nh4)6 (β-p2w18o62) .nh2o that appear at 2θ area under 10º indicates that the compound polioksometalate (nh4)6(β-p2w18o62).nh2o possess extremely high crystallinity due atoms (nh4)6(β-p2w18o62).nh2o regularly by length and angle of bond formed. figure 4b shows the xrd pattern of compound (nh4)6(β-p2w18o62).nh2o/sio2. the compound (nh4)6(β-p2w18o62).nh2o/sio2 has a high crystallinity by the diffraction angle 2θ 8°, 18°, 27° and 34°, respectively which shows the characteristics of the compound polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 where atoms polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2 arranged regularly based on the length and angle of a regular bond. in figure 4b shows the xrd pattern of (nh4)6(βp2w18o62).nh2o/sio2 indicates the diffraction angle changes . acidity test of the compound (nh4)6(β-p2w18o62).nh2o and (nh4)6[β-p2w18o62].nh2o/sio2 quantitatively acidity test of cthe compound (nh4)6(βp2w18o62).nh2o qualitatively measurement of acidity in polyoxometalate compound (nh4)6(β-p2w18o62).nh2o done both qualitatively and quantitatively. qualitatively, ft-ir spectrophotometer was used in which polyoxometalate (nh4)6(β-p2w18o62).nh2o was saturated with ammonia and with pyridine for one day resulting in adsorption on the surface of the compound adsorpsi (nh4)6(β-p2w18o62).nh2o. the saturation result is then compared before or after being saturated with ammonia or pyridine. the spectra of ft-ir compound (nh4)6(βp2w18o62).nh2o of saturation result is presented in figure 5. figure 5. ftir spectrum of (nh4)6(β-p2w18o62).nh2o saturated with pyridine (a), (nh4)6(β-p2w18o62).nh2o saturated with ammonia (b), (nh4)6(β-p2w18o62).nh2o before saturated (c) ft-ir spectrum in figure 5a and b did not find any absorption band at wave number 1400-1440 cm-1 on tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 5 polyoxometalate (nh4)6(β-p2w18o62).nh2o. according to dines et al, (1991) ammonia forms ammonium ions (nh4+) with the observed wave numbers being at 1400-1440 cm-1. in polyoxometalate compound (nh4)6(β-p2w18o62).nh2o saturated with ammonia and pyridine does not show the ammonium ion vibration (nh4+) in the 1400-1440 cm-1 wave numbers range. ammonia can be adsorbed on the acid side of the heteropoly compound as well as on the metal cations which in this study is not observed as figure 5a and 5b. acidity test of compound (nh4)6(β-p2w18o62).nh2o/ sio2 qualitatively the compound (nh4)6(β-p2w18o62).nh2o/sio2 is saturated using ammonia and pyridine just as with section 3.3.1. then the polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 was characterized using a ft-ir spectrophotometer. the saturated ft-ir (nh4)6(β-p2w18o62).nh2o/sio2 spectrum is presented in figure 6. figure 6a shows the spectrum of ft-ir polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 before it is saturated. figure 6b shows the ft-ir spectrum of polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 saturated with pyridine. dines et al, (1991) states that ammonia forms an ammonium ion (nh4+) with an observed wave number at 14001440 cm-1. seo et al (1988) states that ammonia can be adsorbed on the acid side of the heteropoly compound as well as on the metal cation. the compound (nh4)6 (β-p2w18o62) .nh2o / sio2 exhibits the ammonium ion vibration (nh4)6(βp2w18o62).nh2o/sio2 the saturation result is shown in the figure 6. polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/ sio2 saturated ammonia does not exhibit absorption bands at 1400-1440 cm-1 wave numbers. in this case it is possible that the ammonia is not adsorbed on the polyoxometalate (nh4)6(βp2w18o62).nh2o/sio2. khalifah and prasetyoko (2008) explain that pyridine molecules bound to lewis acid sites are absorbed over the 1400-1700 cm-1 wave range. figure 6c shows that the pyridine molecule has been adsorbed by the polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 compound shown in the wave number 1481.33 cm-1. this shows the polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2 having lewis acid properties. acidity test of the compound (nh4)6(βp2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2 quantitatively potentiometric titration method is an analytical technique based on the potential measurement of a sensor or electrode. the electrodes used are glass-containing glassy electrode, the liquid having the potential difference properties between the membrane and the electrolyte in contact with the membrane is determined by the activity of the particular ion. the membrane electrode used is a glass electrode. these glass electrodes are said to be ion-selective because they are specific to h+ ions only. the acidity measurements of (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o /sio2 were carried out quantitatively by measurement using potentiometric titration with n-butylamine as titrant and acetonitrile as solvent. acetonitrile is an aprotic solvent as a solvent in compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(βp2w18o62).nh2o/sio2 so measurable only acidity (nh4)6(βp2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2. according to pecchi et al (1985) the use of benzene, acetonitrile, and iso-octane solvents as solvents in potentiometric titration as a polar solvent to avoid the occurrence of acid or proton adsorption of n-butylamine and acetonitrile as an inert solvent. the measurement by potentiometric method can determine the total acidity and acidity side of a polyoxometalic compound. the initial potential value (ei) identifies acidity strength from the surface side and classifies the acidity strength based on the span divided into scales: ei> 100 mv (acid side is very strong), 0 <ei <100 mv (strong acid side), -100 <ei <0 mv (weak acid side), ei <-100 mv (acid side is very weak) (romanelli et al, 2004). figure 6. ftir spectrum of (nh4)6(β-p2w18o62).nh2o/sio2 saturated with pyridine (a), (nh4)6(β-p2w18o62).nh2o/sio2. saturated with ammonia (b), (nh4)6(β-p2w18o62).nh2o/sio2 before saturated (c) the first and second derivative curves are made to see where the titration equivalent point is shown in figures 7b and 7c. equivalent point is performed to see the condition where the base of n-butylamine is added precisely reacts with the compound (nh4)6(β-p2w18o62).nh2o being titrated. in addition, an equivalence point is performed to determine the amount of base volume of n-butylamine needed to neutralize the (nh4)6(β-p2w18o62).nh2o/sio2 compound which is considered to be acidic. figure 7a shows the result of measurement of compound (nh4)6(β-p2w18o62).nh2o has an initial potential value of 61.96 mv. based on the potential value range 0 <ei <100 polyoxometalate (nh4)6(β-p2w18o62).nh2o has a strong acid side. the titration equivalent point is at 0.8 ml of ntambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 6 butylamine volume reinforced by the first derivative curve and the second derivative of potentiometric titration data. the titration equivalent point can be observed with sharp potential changes (mulja and suharman, 1995). figures 7b and 7c show the first derivative curves and the second derivative curves of the polyoxometalate (nh4)6(β-p2w18o62).nh2o. figure 7. titration curves of polyoxometalate compound of (nh4)6(β-p2w18o62).nh2o (a), titration curve first derivate (b), titration curve second derivate (c) the measurement of the acidity of the polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 quantitatively is also carried out through potentiometric titration. from the titration curve presented in figure 7, the titration equivalent point is obtained when the titration volume is 0.8 ml n-butylamine. based on equivalence point data, it is found that polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 compounds require more nbutylamine base volume to neutralize the polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2. this indicates that (nh4)6(β-p2w18o62).nh2o/sio2 is more acidic than the polyoxometalate compound (nh4)6(β-p2w18o62).nh2o. this is also supported by looking at the potential initial value comparison. the initial potential value of polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2 is 76.16 mv whereas the initial potential value of polyoxometalate (nh4)6(βp2w18o62).nh2o amount 61,96 mv. the compound (nh4)6(βp2w18o62).nh2o/sio2 is included in the acid classification having a strong acid side based on the potential acid strength value range. increasing the safety of the polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 compound due to the compound (nh4)6(β-p2w18o62).nh2o interacts with the carrier sio2 derived from tetraethyl orthosilicate. the titration curve of potentiometric compound (nh4)6(β-p2w18o62).nh2o/sio2 can be seen in figure 8. figure 8. titration curves of polyoxometalate compound of (nh4)6(β-p2w18o62).nh2o/sio2 (a), titration curve first derivate (b), titration curve second derivate (c) the effect of temperature on the stability of the compound (nh4)6(β-p2w18o62).nh2o/sio2. the compound (nh4)6(β-p2w18o62).nh2o/sio2 was heated at various temperatures to see the effect of temperature on the stability of the compound (nh4)6(βp2w18o62).nh2o/sio2. the heating results of the compound (nh4)6(β-p2w18o62).nh2o/sio2 at various temperatures were characterized by an ft-ir spectrophotometer. figure 9 shows the spectrum of ft-ir polyoxometalate compound (nh4)6(βp2w18o62).nh2o/sio2 without heating and heated at various temperatures from 200-600°c. in figure 9 shows the difference shown by ft-ir spectrum of polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2 before and after heated at the temperature range 200-600ºc. based on the ft-ir spectrum of compound (nh4)6(β-p2w18o62).nh2o/ sio2 which is warmed up the vibrations appear to have shifted wavenumbers. tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 published under the terms of the cc by nc sa 4.0 license 7 figure 9. ftir spectrum of of (nh4)6(βp2w18o62).nh2o/sio2 at various temperatures (a) 600ºc, (b) 500ºc, (c) 400ºc, (d) 300ºc, (e) 200ºc, (f) (nh4)6(βp2w18o62).nh2o/sio2 before heated. figure 9 shows the presence of -oh groups in the presence of h2o observed in the range of 3400-3500 cm-1. vibration of polyoxometalate compound (nh4)6(β-p2w18o62). nh2o/sio2 in the wavenumber 800-1000 cm-1 at 600ºc indicates a difference caused by vibration w = o, w-oe-w vibration and vibration woc-w has been lost. this indicates that on the increase of temperature on heating can cause structure change of polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2. at a temperature of 200ºc shows little difference due to vibration w = o that overlap with vibration w-oe-w and w-oc-w, whereas with temperature 300ºc vibration w = o and w-oew was disappeared. this indicates an increase in the heating temperature which may cause changes in the structure of the polyoxometalate (nh4)6(β-p2w18o62).nh2o/sio2. conclusion polyoxometalate compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2 has been succesfuly prepared which is characterized by the vibration of the polyoxometalate group as results of the characterization of the ft-ir spectrofotometer. vibration of the polyoxometalate compound (nh4)6(β-p2w18o62).nh2o shows the presence of vibration w=o appear on the area 964.41 cm-1, w-oc-w appear on the area 786.96 cm-1, w-oe-w appear on the area 918.12 cm-1, p-o appear on the area 1087.85 cm-1, and polyoxometalate compound (nh4)6(β-p2w18o62).nh2o/sio2 shows the presence of vibration w=o appear on the area 1049.28 cm-1, w-oc-w appear on the area 794.67 cm-1, w-oew appear on the area 918.12 cm-1, p-o appear on the area 1087.85 cm-1,o-h appear on the area 3464.15 cm-1, si-o appear on the area 470 cm-1. xrd diffraction patterns show polyoxometalate compound (nh4)6(β-p2w18o62).nh2o and (nh4)6(β-p2w18o62).nh2o/sio2 has a high crystallinity with an angle of diffraction 2θ each of them 8°-34°. compound (nh4)6(β-p2w18o62).nh2o/sio2 has high acidity compared with the compound (nh4)6(β-p2w18o62).nh2o acidity test quantitatively. the impact temperature on the stability of the compound (nh4)6(β-p2w18o62).nh2o/sio2 shows of the temperature 600ºc there is a shift of compound wavenumbers (nh4)6(β-p2w18o62).nh2o/sio2. references contant, r., abbessi, m., thouvenot, r., herve., 2004, syntheses and 31p, 51v,and 183w nmr structural investigation of octadeca (molybdo−tungsto−vanado) diphosphates related to the [h2p2w12o48]12anion. inorganic chemistry, 43, 3597. dines, t. j., colin h. r., and andrew m. w., 1991. infrared and raman study of the adsorption of nh3, pyridine, no and no2 on anatase. journal chemical society, 87, 643-651. fatimah, i, 2009, peningkatan aktivitas katalitik tio2 dan zro2 melalui pengembanan pada matriks al2o3-montmorillonit. laporan akhir kegiatan hibah penelitian untuk mahasiswa program doktor, ugm. finke, r.g, droege, m.w, domaille, p.j, 1987, trivacant heropoly tungstate deviratives. 3.1. rational syntheses, characterization, two-dimentional183w nmr, and properties of p2w18m4(h20)2o6210and p2w30m4(h20)2o11216(m= co, cu, zn), inorganic chemistry, 26,3886-3896.. khalifah, s.n., and prasetyoko, d, 2008, sintesis dan karakterisasi zsm-5 mesoporous dengan variasi rasio sio2/al2o3. surabaya tambunan et al. / science and technology indonesia 2(1) 2017:1-8 @2017 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(2017). synthesis, characterization, and thermal stability of k8[siw11o39]nh2o/sio2. science & technology indonesia, 1(1), 8-15. seo, gon., jeong woo lim., jong taik kim., 1988, infrared study on the adsorbed state of ammonia on heteropoly compounds. journal of catalysis, 114, 469-472. smith, b. 1999. infrared spectral interpretation : a sytematic approach . crc press, new york. yamase, t.;pope, m. t. eds, 2002, polyoxometalate chemistry for nano-composite design; kluwer: dordrecht. the netherlands. yang, shuijin. yongkui huang., and li yu, 2011, catalytic application of h4siw12o40/sio2 in synthesis of acetals and ketals. advanced materials research, 284-286, 2374-237 title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 2, april 2018 research paper factors of medicinal plants users as alternative medicinal in indonesia yunita theresiana1*, m.t. kamaluddin2, sriati3, lili erina4 1 doctoral program of environmental science, graduate program of sriwijaya university, jl. padang selasa, no. 524, palembang indonesia 2 faculty of medicine, sriwijaya university, indonesia 3 faculty of agriculture, sriwijaya university, indonesia 4 faculty of social and political science, sriwijaya university, indonesia *corresponding author: yunita_theresiana@yahoo.co.id abstract traditional medicines are the cultural heritance of indonesian that should be preserved and developed in order to support the society’s health development and to improve the society’s economy. this research was aimed to figure out the society’s behaviors in using traditional medicines and the dominant factors that influence them in using traditional medicines. this research is a non-experimental research, with analytical survey method and cross sectional approach. the data were analyzed descriptively. the sample and the population were grouped into district clusters. this research is an analytical survey with cross sectional approach which aims to (a) analyze the behavior of society of traditional drug utilization based on perception of sickness, type of complaint, residence, distance to health facility, health, family support, and promotion of traditional medicine. (b) identify the dominant factors that influence the community in using traditional medicine.the study was conducted in ogan ilir district of south sumatera province. the respondents were motivated to use traditional medicines through (a) predisposing factors perceived sickness; (b) enabling factors, including economic level, location of domicile, type of complaints, insurance and distance to health facilities; and (c) reinforcing factors, including family support and traditional medicine promotion. serving as the predicting factors in the traditional medicine use were the variables perceived sickness, type of complaint, distance to health facilities and traditional medicine promotion, with the variables occupation, insurance, education, family support, domicile and income serving as the confounding variables. keywords behavior, medicinal plants, alternative medicinal received: 2 january 2018, accepted: 25 march 2018 https://doi.org/10.26554/sti.2018.3.2.94-99 1. introduction according to regulation of the government of the republic of indonesia no. 08 of 1999, the use of plants is conducted in the interest of sustainable utilization of plants for the greatest prosperity of the society. the plant or its part or product is used while maintaining the diversity and balance of the ecosystem (kartika, 2015). indonesia is rich in di�erent local wisdom concerning medicinal plants, many of which have not been used for medication. given that many plants have properties which have not been identi�ed and developed clinically and modernly. it is necessary to conduct continuous exploration, research, testing and development of medicines. there has been a tendency of increase in the use of natural ingredients, particularly medicinal plants, today. the medicinal plants processed as traditional medicines since ancient times now have been widely used, especially by middle to lower society. with the advance in technology, now many kinds of medicinal plants have been processed and packaged modernly. this has developed into a healthy lifestyle in a natural way (adams et al., 2009). self-medication/swamedikasi by the community is an e�ort that many people do to overcome the complaints or symptoms of disease, before seeking help to the nearest health service facility or health worker. in 2013 basic health research results showed that a total of 103,860 people or 35.2 percent of 294,959 households in indonesia store medicine in households, either from prescription or independently purchased. the proportion of people prescribing hard drugs without prescriptions reaches 81.9 percent of them including antibiotics of 27.2 percent and the rest as "supply drugs" if they are sick and "remnant drugs" of 32.1 percent of households, and the likelihood that the number of self-medication treatment will continue to increase every year. the cultural heritage (local wisdom) of medicinal plants can in fact be managed properly as �rst-aid medicines to treat various kinds of diseases, but the properties of such plants have https://doi.org/10.26554/sti.2018.3.2.94-99 theresiana et. al. science and technology indonesia, 3 (2018) 94-99 mostly never been standardized for proper use. to preserve the nature in order to maintain the existance of medicinal plants and their healing properties, to allow for broader and more prevalent use of medicinal plants, and to preserve and promote the nation’s cultural heritage, it is necessary to conducte continuous exploration, research, testing and development of traditional medicines and medication. many of the plant riches growing in indonesia are utilized by other nations for research, and evantually to be processed into more useful medicines, while we, to whom those reaches belong, mostly put heavier trust to medical treatment only (ma�misebi and oguntade, 2010). 2. experimental sectipn 2.1 instrument and data collection this research is an analytical survey with cross sectional approach which aims to (a) analyze the behavior of society of traditional drug utilization based on perception of sickness, type of complaint, residence, distance to health facility, health, family support, and promotion of traditional medicine. (b) identify the dominant factors that in�uence the community in using traditional medicine.the study was conducted in ogan ilir district of south sumatera province from july to december 2016 with a sample of 400 samples, then the population was grouped into village clusters. from the number of existing villages, 50 percent were taken randomly to be sampled. from this selected village then the research sample is selected by random sampling to get a number of 400 samples.the instrument in this study used a modi�ed questionnaire based on a questionnaire survey of basic health research (riskesdas, 2013). nevertheless, the questionnaire remains validity and reliability test. the tested questionnaires were conducted to determine the validity and reliability of 8 parts, namely the variables of complaints, sickness perception, health insurance, family support, and promotion of traditional medicine. trial conducted on the community in banyuasin regency, due to the similarity of character with the community of ogan ilir regency. the analysis of questionnaire test was calculated using product moment statistic method from pearson.the results of the questionnaire on variables of the types of complaints, sickness perception, health insurance, family support, and promotion of traditional medicine when viewed in the table corrected itemtotal correlation indicate that from 12 questions, it turns out that the value of r count is no smaller than the value of r table. the r value of the table at n 20 is 0.235. this means that all questions are valid to be used as a measuring tool. for reliability test, in this research used cronbach alpha method, which is a method which is done by comparing between r value with r table value. the value of r arithmetic is represented by the cronbach alpha value. if the value of cronbach alpha obtained is greater than the value of r table, then the instrument declared reliable. from the experiments conducted for the variable variable of complaint type, pain perception, health insurance, family support, and promotion of traditional medicine, the value of cronbach alpha all variables greater than r table (0,235), it can be concluded that the variable of type of complaint, perception illness, health insurance, family support, and promotion of traditional medicine pass the reliability test. data collection techniques with interviews are interviews about the behavior of traditional drug utilization and other factors collected by using questionnaires to obtain primary data. observation method is observation done on the use of medicinal plants directly, by looking at what drugs are stored by the respondents, both modern medicine and traditional medicine. document survey method to see name, age, gender, address. 2.2 data processing and analysis data processing consists of several steps, such as: editing, processing, tabulating , coding and entrying. then, data processing was done electronically by using spss program. the data analysis was univariate and bivariate analysis with chi square test. the sample in this research is part of ogan ilir regency who is 15 years old and above and willing to be interviewed. in this study the researchers used the slovin formula, to obtain a minimal sample size, with the following formula: n = n 1+nα2 (1) where n is the amount of the sample, n is the number of population, α is the error tolerance = 0.05, so the the minimum sample size is 399,62 rounded to 400 samples. 3. results 3.1 characteristic of respondents the analysis was conducted on perception of sickness, type of complaint, residence, distance to health facility, health, family support, and promotion of traditional medicine. this study uses primary data, that is data obtained from questionnaires distributed to residents of ogan ilir regency who were chosen at random. the result of univariate analysis as follows: based on table 1. described that the perception of illness variable is into four categories namely: bad, medium, healthy, and very healthy. from table 1 it can be seen that from 400 respondents, most of them have healthy perception, that is 243 people (60.8%), then 82 respondents (20.5%) feel health condition in medium condition, and the rest, which amounted to 75 people (18.8 percent) feel very healthy. the result of analysis it can be seen that the number of respondents who live in rural areas is more than 257 people (64.3 percent) compared with respondents who live in urban areas, that is 143 people (35.8 percent).the type of complaint is divided into two categories, namely chronic and acute. from table 1. it can be seen that the number of respondents who stated that they su�er from acute illness is bigger, that is 222 people (55,5%) compared with respondents who su�er from chronic disease, that is only 10 people (2.5%), did not know © 2018 the authors. page 95 of 99 theresiana et. al. science and technology indonesia, 3 (2018) 94-99 table 1. univariate test results of research variables no variable frequency ( n ) percentage 1 perception of illness 1. bad 0 0 2. medium 82 20.5 3. healthly 243 60.5 4. very healthly 75 18.8 2 residential place 1. rural 257 64.3 2. urban 143 35.7 3 type of complaint 1. chronical 10 2.5 2. sereve 222 55.5 3. not available 168 42 4 revenue 1.≤ rp 1.000.000/month 69 17.3 2. > rp 1.000.000/month 331 82.8 5 health insurance 1. no 116 29 2. yes 284 71 6 distance to health facility 1. far 127 31.8 2. near 21 68.3 7 family support 1. available 379 94.8 2. not available 21 5.3 8 promotion of traditional medicine 1. available 2. not available 379 94.8 21 5.3 amount 400 there were as many as 168 people (42.0 percent). the type of complaint is divided into two categories, namely chronic and acute. the result of analysis of the number of respondents who stated that they su�er from acute illness is bigger, that is 222 people (55,5%) compared with respondents who su�er from chronic disease, that is only 10 people (2.5%), did not know there were as many as 168 people (42.0 percent).income variables are divided into three categories, namely > rp 1,000,000 / month, and ≤ rp 1,000,000 / month. table 1. shows that out of 400 respondents, most of the income> rp 1,000,000 / month, is 331 people (82.8 percent), while those with income ≤ rp 1,000,000 / month there are 69 people (17, 3 percent). the insurance variable is divided into two categories, i.e. yes (if the respondent has at least one health insurance membership card is still valid) and not (if the respondent does not have any health insurance membership card). from table 1. it can be seen that the number of respondents who become the participant of health insurance is more, that is as much 284 people (71,0 percent) compared with respondents who do not become health insurance participant, that is 116 people (29,0 percent) from 400 respondents under research. based on the results of this study, it is known that the closest distance to the nearest facility can be reached within 3 minutes, while the farthest can be reached within 60 minutes, and the average value (mean) is 19.17 minutes. in this study, health facility distance variables are divided into two categories, ie far (when the distance to the facility of means > mean) and close (when the distance to the facility of safety ≤ mean). from table 1 it can be seen that the number of respondents whose residence is near to health facility is 273 (68.3%) more than respondents whose residence is far from health facility, that is 127 people (31.8% of the 400 respondents under survey. family support variables are divided into two categories, that is, and none exist. in this study it can be seen that from 400 respondents, who claimed to have family support in utilizing traditional medicine © 2018 the authors. page 96 of 99 theresiana et. al. science and technology indonesia, 3 (2018) 94-99 is greater, that is as many as 379 people (94.8 percent) compared with respondents who do not get the support of their family, that is only 21 people (5, 3 percent). the promotional variables of traditional medicine are divided into two categories, is there (if the respondent has ever received information about traditional medicine) and none (if the respondent never gets information about traditional medicine). the result of analysis of the number of respondents who have received more traditional drug promotion, that is as many as 250 people (62.5 percent) compared with respondents who never get the promotion of traditional drugs, which amounted to 150 people (37.5 percent) 400 respondents under research, of the 400 respondents under survey. 4. discussion in this research, the variables of traditional medicine use were devided into two, namely use (if the respondents stored traditional medicines in any form within 12 months before the research was conducted) and non-use (if the respondents did not store any traditional medicine in any form within 12 months before the research was conducted). from the analysis results, it was �gured out that the number of respondents using traditional medicines was higher, which was at 255 (63.8 percent), than those who did not use any traditional medicine, which was at 145 (36.3 percent). the results of this research were slightly higher than those of 2010 riskesdas, stating that 55.3 percent of respondents claimed themselves as loyal consumers of traditional medicines (jamu). the 2013 riskesdas data showed that the proportion of households storing traditional medicines at their houses was 15.7 percent, and the proportion of households using traditional health service was 30.4 percent. meanwhile, based on the results of the national sosioeconomic survey (susenas), the use of traditional medication increases from year to year. in 2010, the use of traditional medication increased into 45.17 percent, and in 2011 it increased again into 49.53 percent (kemenkes, 2010). according to the research conducted by supardi and susyanty (2010) analyzing the 2007 susenas, 55.8 percent of the whole household sample did self-medication, including traditional medication, for treating their diseases. according to the data from the central agency for statistics (bps), the percentage of population had self-medication traditionally was 23.89 percent in 2011, 24.42 percent in 2012, 21.59 percent in 2013, and 20.99 in 2014. these di�erences is possibly due to the di�erence in the sample size, as the surveys abovementioned used big-sized samples. the 63.8-percent prevalence is arguably high, and it can be assumed that it is derived from the fact that the majority of the respondents of this research believed that traditional medication is acceptable for the people of ogan ilir regency. the wider accountability of traditional medication in this region is possible due to the cultural acceptance, easy access, and a�ordability of traditional medicines in comparisn to modern medicines and facilities. the knowledge about traditional medicines is the primary determinant for users. individuals and society may obtain various forms of information on traditional medicines from di�erent sources due to numerous reasons. this research also attempts to analyze the various sources from which the respondents gained information on the traditional medicines they used. the analysis results show that most of the respondents gained the information on traditional medicines from their family/friends/contacts, numbering 133 (52.2 percent). this �nding is worth noting as the knowledge on traditional medicines is mostly passed down or obtained through training based on spken tradition from family members and parents. moreover, it was found out that media, either printed or electronic, are important sources of information on traditional medicines. as many as 21.2 percent (52) respondents reported that books and internet were their main sources of information on traditional medicines. this �nding a�rms that the various forms of information media developing today may serve as e�ective marketing tools for promoting traditional medicines. it is an undeniable truth that the society today have higher awareness of technological advances, so any form of information and advertisement of traditional medicines now is easily accessible through di�erent media, either printed or electronic. however, 11.8 percent respondents (47 people) stated that they gained information on traditional medicines from docters/other health personnels. this underlines the existence of competition, sceptisism, distrust and suspicion between traditional and modern medications in medical practices (buor, 2004). traditional medicines are often used for treating or preventing various health conditions. currently, traditional medicine users seem to be highly dependant on their family, friends and media to obtain information. in terms of frequency of use, most traditional medicine users (204 people or 80 percent) used traditional medicines once in a month, 37 users (14.5 percent) used traditional medicines once in a week, and 14 users (5.5 percent) used traditional medicines once in a year. in relation to the place from which respondents obtained the traditional medicines, it was found out that 79.2 percent (2012 respondents) concocted their medicines on their own. this modality normally occured in respondents as the various ingredients and substances they knew were easily available in their back yards. the other sources of traditional medicine were medicine sellers/public markets (12.2 percent), pharmacies (2.0 percent), traditional medication practicioners (1.2 percent) and other places (5.5 percent). the majority of the respondents used the traditional medicines widely known for treating particular conditions and applied them personally when they or one of their family members had the same conditions. those medicines were obtained from their home yard or within their neighborhood. this signi�es that most users knew the practice of herbal medication passed down from the older generations through informal training, folktales, and verbal communication. some others gained the ability to concoct the traditional medicines through dreams © 2018 the authors. page 97 of 99 theresiana et. al. science and technology indonesia, 3 (2018) 94-99 table 2. the results of bivariate test variables utilization of traditional drugs frecuency p valueyes no n % n % n % perception of illness 1. medium 66 80.5 16 19.5 82 100 0 2. healthy 180 74.1 63 25.9 243 100 3. very healthy 9 12 66 8 75 100 residential place 1. rural 185 72 72 28 257 100 0 2. urban 70 49 73 51 143 100 type of complain 1. chronic 0 0 10 100 100 100 0 2. acute 131 59 91 41 222 100 3. unware 124 73.8 44 26.2 168 100 revenue 1. ≤ rp1.000.000/month 61 88.4 8 11.6 100 0 2. > rp1.000.000/month 194 58.6 137 100 health insurance 1. yes 104 89.7 12 10.3 116 100 0 2. no 151 53 133 46.8 284 100 distance to health facility 1. far 92 72.4 35 27.6 127 100 0.019 2. near 163 59.7 110 40.3 273 100 family support 1. yes 247 65.2 132 34.8 379 100 0.023 2. no 8 38.1 13 61.9 21 100 promotion of traditional medicine 1.yes 170 68 80 32 250 100 0.03 2.no 85 56.7 65 43.3 150 100 and sometimes supernatural powers (ma�misebi and oguntade, 2010; okunlola, 2007). this practice may lead to indiscriminate and unprescribed medication leaving both positive and negative impacts. some other studies (van andel and carvalheiro, 2013; peltzer and mngqundaniso, 2008) also found out that disease prevention in may households usually starts from home (beyond health facilities) by using traditional medicines. these medicines are obtained from various sources such as alternative medication (witchdoctors, traditional bone setter, traditional birth attendants, spiritualits, etc), self concoction, pharmacy, and so forth. usually, conventional medical service is only sought when the disease develop 5. conclusions respondents were motivated to use traditional medicines by (a) predisposing factors, namely: perceived sickness. (b) enabling factors, namely economic level, domicile, type of complaint, insurance, and distance to health facilities, and (c) reinforcing factors, namely family support and traditional medicine promotion. this research found that the factors serving as predictors in the use of traditional medicines were the variables sex, ethnic group, perceived sickness, type of complaint, distance to health facilities, and traditional medicine promotion, with variables occupation, insurance, education, family support, domicile, and income serving as confounding variables. in addition, the statistical test showed no signi�cant di�erence between age groups in the use of traditional medicines. with the results of this research, it is expected that a number of strategies for improving the practice of traditional medicine use in the public health care are formed. those, the following policy recommendations are proposed as a means for improving traditional medicine use. © 2018 the authors. page 98 of 99 theresiana et. al. science and technology indonesia, 3 (2018) 94-99 references adams, j., d. sibbritt, and a. young (2009). a longitudinal analysis of older australian women’s consultations with complementary and alternative medicine (cam) practitioners,1996-2005. age ageing, 38; 93–99 kartika, t. (2015). inventarisasi jenis-jenis tumbuhan berkhasiat obat di desa tanjung baru petai kecamatan tanjung batu kabupaten ogan ilir (oi) provinsi sumatera selatan. sainmatika: jurnal ilmiah matematika dan ilmu pengetahuan alam kemenkes (2010). risetkesehatandasar (riskesdas), 2010. balai penelitian dan pengembangan kesehatan, kementerian kesehatan republik indonesia ma�misebi, t. e. and a. e. oguntade (2010). preparation and use of plant medicines for farmers’ health in southwest nigeria: socio-cultural, magico-religious and economic aspects. journal of ethnobiology and ethnomedicine, 6(1) okunlola, j. o. (2007). the sociology of the use of medicinal plants. in medicinal plants in agriculture: the nigerian experience. in proceedings of the akure-humboldt kellog/3rd saat peltzer, k. and n. mngqundaniso (2008). patients consulting traditional health practitioners in the context of hiv/aids in urban areas in kwazulu-natal. south africa. afr. j. trad., 5(4); 370 – 379 riskesdas (2013). pertanyaan rumah tangga dan individu. badan penelitian dan pengembangan kesehatan, republik indonesia kementerian kesehatan supardi, s. and a. l. susyanty (2010). penggunaan obat tradisional dalam upaya pengobatan sendiri di indonesia (analisis data susenas tahun 2007). buletin penelitian kesehatan, 38; 80–89 van andel, t. and l. g. carvalheiro (2013). why urban citizens in developing countries use traditional medicines: the case of suriname. complementary and alternative medicinecomplementary and alternative medicine, 114 © 2018 the authors. page 99 of 99 introduction experimental sectipn instrument and data collection data processing and analysis results characteristic of respondents discussion conclusions science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 2 (2017) 9-16 arti cle http://sciencetechindonesia.com © 2017 published under the terms of the cc by nc sa 4.0 license 9 bentonite intercalated organometallic complex as adsorbent of procion red lora vitanesa1, radja nardo purba1, aldes lesbani1, and m uhammad said1 1department of chemistry faculty mathematic and natural science, sriwijaya university *corresponding author e-mail: loravitanesa@gmail.com abstract insertion of bentonite with organometallic compounds [cr3o(ooch)6(h2o)3 (no3)]as adsorbent of procion red with comparison weight ratio of bentonite: organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] i.e.: (2.5:1), (1:1), (1:2) and (1:3) has been done. the results of insertion bentonite were characteriz ed using ft-ir spectrophotometer, xrd, and xrf. furtherm ore, the product of optim um insertion was used as an adsorbent of procion red. the spectrogram from ft-ir shows the process of insertion was not optim um for every weight ratio. characterization using xrd showed the optim um insertion process ratio (1:2) and (1:3) was indicated the presence of diffraction appearing at 2θ region by a shift in the diffraction angles 5.00 and 39o from the original activated bentonite of 20.8o. characterization using xrf analysis in the ratio (1:3) shows percentage of metal oxide cr2o3 increase to 82.28%, so at the ratio of 1:3, the process insertion of organometallic compounds into the bentonite has stated success base on its highest percentage. the adsorption process of insertion bentonite organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] ratio (1: 3) shows the magnitude of the rate of adsorption (k) at 0.004 m in-1, the adsorption capacity (b), the largest at a temperature of 70oc at 72.99 mol/g, the largest adsorption energy (δg) at a temperature of 60oc i.e. 17.05 kj / mol, the largest enthalpy (δh) is 105720.8 kj/mol, entropy (δs) 315 kj/mol and ph 11 has the biggest value of procion red adsorped, i.e. 33.38 mg/l. keywords: bentonite, organometallic compound [cr3o(ooch)6(h2o)3(no3)].adsorption, procion red intro duction bentonite is one of the minerals whose abundance is quite large in nature, especially in indonesia. bentonite spread on the islands of borneo, sumatra, sulawesi and java. bentonite is the most clay consists of montmorillonite with mineral such as quartz, calcite, dolomite, feldspars, and other minerals. bentonite has the chemical formula [(oh)4si8al4o20nh2o] which is silicate and alumina compounds contain chemical l y bound water (sukandarrumidi, 1999). bentonite is clay minerals that have easy properties expand has cations in part layer that can be interchangeable so that the properties are very suitable to use as adsorbent and catalyst (dewi and hidayati, 2012). the need for bentonite in the world industry tends to increase as adsorbent and catalyst but ability bentonite adsorption is generally not high because bentonite has a small spacing between layers and still, has im purity minerals (noyan et al., 2007). bentonite modifications can be carried out by means of chemical activation, physics activation as well as the insertion of the compound on the intercellular surface coated bentonite using an insertion compound. bentonite modification is expected produce bentonite that has stability and distance between large layers. during this process inserted bentonite done with micro cations which is a compound the amine group (altunlu and yapar, 2007) and iron aluminum complex (caglar et al., 2015). article history received: 9 october 2016 accepted: 12 december 2016 doi: 10.26554/sti.2017.2.1.9-16 yolani (2012) conducted the research about the modified bentonite inserted metal aluminum uses poly diallyl dim ethyl ammonium as the adsorbent of sodium dodecyl benzene sulphonate. wang et al. (2009) also do inserted bentonite research with aluminum using ammonium salt quarterner. the results shows metal bentonite inserted with aluminum is shifting at an angle diffraction 8.4359o with basal spacing value equal to 10.4817 is in region 2θ and wang's research shows bentonite insertion of aluminum using salt quaternary ammonium undergoes shifts at 9.0941 å diffraction shrinkage with basal spacing of 9.72449 å is in the area 2θ. the product developed by yolani (2012) and wang (2009) have not been effective used as an adsorbent, because of the distance between the resulting layer is still small. this matter resulting from aluminum cations small size so cannot yet open the bentonite layer. to im prove its effectiveness as an adsorbent, it required macro cations to produce a bentonite that has large interlayer spacing. the large size of macro cation was developed by lesbani (2008) which is a complex compound or organometalli c synthesis results in the laboratory. macro cation that used in synthesis ionic crystal macromolecules has the ability as adsorbents and also has ability as a catalyst (uchida et al, 2012). utami and siburian (2016) was reported the organometalli c trinuclear complex as intercalant for bentonite. in this research , it will do the insertion on bentonite using compound complex organometallic [cr3o(ooch)6(h2o)3 (no3)]. the bentonite inserted using organometallic compounds [cr3o(ooch) 6 (h2o)3 (no3)], before and after will be characterized using a spectrophotometer ft-ir, xrd and xrf analysis, then applied as adsorbent of procionred. in addition, the factors such as kinetic parameters, parameters thermodynamics, the effect of vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 10 ph of the solution, of influence the weight of adsorbent were also be determined. experimental section instrumentations the tools used in this research is a set of glass tools, filter paper, magnetic stirrer, bath (hotplate), vacuum, oven, dropper drops, balance sheets analytical, uv-vis spectrophotometer (thermo scientific genesys 20), x-ray diffraction (shim adzu lab x-type 6000), spectrophotometer ft-ir (shim adzu-pertige21), and x-ray fluorescence (pan analytical type minipod) material ingredients used in this research is bentonite, aquadest, chromium (iii) nitrate nonahydrate compound [cr(no3)3. 9h2o], formic acid, sulfuric acid, sodium hydroxide, hydrochloric acid, nitrogen gas, procion red dye. procedures preparation of bentonite and characterization bentonite is obtained from the district sarolangun jambi province. bentonite sample which is obtained at a furnace at a temperature of 400oc, and then added sulfuric acid and distilled water for 2 hours then dried. bentonite is then smoothed in a way pulverized and filtered. characterization of bentonite is done by using xrd, ft ir spectrophotometer, and analysis xrf. synthesis of organometallic compounds [cr3o(ooch)6(h2o)3 (no3)]and it's characterization (lesbani et al.2008). organometallic compounds [cr3o(ooch)6(h2o)3(no3) ] . is synthesized by: cr(no3)3·9h2o as much as 40 grams is added 50 ml distilled water. stirred by using magnetic stirrer, and then added 3 m naoh of 10 ml for 10 min so that green solution is obtained. the green solution is filtered, the sedim ent taken and added formic acid as much as 12.5 ml and refluxed for 2 hours. the reflux solution is then filtered, and obtained by green crystals. green crystal that has been dry analyzed using ft-ir spectrophotometer. inorganic compound insertion [cr3o(ooch)6(h2o)3 (no3)] into bentonite and its characterization (kouraichi et al.2015). bentonite is made in the form of suspension by mixing as much as 2.5 grams bentonite is activated with 200 ml of distilled water plus 100 ml of mixed naoh with 1, 2.5, 5, 7.5 gr of organometallic compound while stirring using magneti c stirrer for 24 hours at room temperature while being fed by nitrogen gas. the results are obtained then filtered and dried. the solid of insertion result is characterized using xrd, ft-ir spectrophotometer and xrf analysis. determination λ maximum color substance procion red determination of maxim um wavelength obtained by measuring the absorbance of the substance color procion red with spectrofotometer uv-vis at wavelength 400-600 nm so that will get the wavelength maxim um. absorption process of procion red using adsorbent bentonite inserted organometallic compound [cr3o (ooch)6(h2o)3(no3)]. effect of adsorption time (tien & ramarao, 2014). a total of 0.1 grams of bentonite adsorbent activated and inserted bentonite added into 50 ml of concentrated dye 100 ppm horizontally stirred using shaker at the tim e interval that has been determined. variation of adsorption tim e varied ranging from 10, 20, 30, 40, 50, 60, 70, 80 and 90min. the dyestuff solution has passed through the adsorption process is separated, then measured concentration by using uv-vis spectrophotometer. the influence of concentration and temperature (mahmoud et al. 2016). a total of 0.1 grams of bentonite adsorbent activated and inserted bentonite mixed with 50 ml of dye solution (0.5, 10, 25, 50, 100 mg/l) for insulated and bentonite (0.5, 10, 25, 40, 60 mg/l) for bentonite activated stirred by using shaker for 30 minutes at that temperature varied i.e. 30, 40, 50, 60, 70oc. the mixture is filtered, and then the substance of the color that has been separated from the adsorbent is measured using uv-vis spectrophotometry to know the concentration of residual colo r substances after color absorption process. effect of ph activated and inserted bentonite as much as 0.1g added to 50 ml dye solution then stirred horizontally using a shaker at room temperature for 10 minutes. ph of dye solution is set at 3, 4, 5, 6, 7, 8, 9, 10, 11, with the addition of 0.1 m naoh and 0.1 hcl m. the color solution is then separated and residual concentration after the adsorption process was measured using a uv-vis spectrophotometer. spectroscopic and diffraction studies as much as 0.1 gram of adsorbent is m ixed 50 ml of dye with concentration 100 mg/l and 60 mg/l. the mixture is stirred using horizontal shaker for 1 hour. the mixture is separated by process filtering and then adsorbed dried adsorbents were analyzed using ft-ir spectrophotometer to know changes before and after the process adsorption. data analysis the success of the bentonite insertion process with organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] is observed from the data xrd, ft-ir spectrophotometer, and analysis xrf. it is expected the insertion process only require one layer using a compound organometalli c [cr3o(ooch)6(h2o)3 (no3)] to form a workable bentonite by observed the effect of kinetic and thermodynamic parameters , aand the effect of ph of the bentonite kinetics solution insertion of organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] for ddetermine the absorption rate with assume that the adsorption process ooccurs following the model of the adsorption equation langmuir as follows: vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 11 where : co: initial concentration of procion red, c: procion red concentration after tim e t, c: residual concentration, k1: slope t: the adsorption tim e that follows langm uir's adsorption equation model, k: intercept parameter thermodynamics of adsorption process bentonite insertion [cr3o(ooch)6(h2o)3 (no3)] i.e. δh, δs, δg are determined by the following equation: e ads = δgads = rt ln k where : kd: coefficient of adsorbate distribution (qe/ce), δh: enthalpy, δs: entropy, r: general gas constant (8.314 j / mol k) and q: temperature the bonds formed between the adsorbate and the adsorbent is studied through spectroscopy and diffraction compared with adsorbent before the interaction of inserted bentonite organometallic compounds [cr3o(ooch)6(h2o)3(no3) ] . absorption capacity is based on formula: where : c: the concentration of metal ions in the solution at equilibrium, k: contants of eqilibrium , m : adsorbent mass, b: adsorption capacity results and discussion result of synthesis and characterization of compounds organometallic [cr3o(ooch)6(h2o)3(no3)] using spectrophotometer ftir organometallic compounds [cr3o(ooch)6(h2o)3(no3) ] was synthesized under atmospheric conditions without any special protection against ligands (l) as well as organic groups (r) so that easy to do. during the synthesis process, formic aci d was added and reflux process is done for 2 hours to obtain a green crystal solid which is an organometallic compound [cr3o(ooch)6(h2o)3(no3)]. the organometallic compounds was characteriz ed using ft-ir spectroscopy to know the presence of μ-3 chromium -oxygen group as the typical of symmetrical organometallic compounds (ohto et al., 1995). the ft-ir spectra of organometallic compounds [cr3o(ooch) 6 (h2o)3(no3)]. is presented in figure 1. figure 1 shows the specific vibrations μ -3 that known as cr3-o in organometallic [cr3o(ooch)6(h2o)3(no3)]. appears on wave number 648 cm -1 with sharp intensity. the presen ce of formic acid groups which are c-h vibrations and o-h vibrations is identified at wave number 2924-3425 cm -1 which are specific characteristi c of the aliphatic compound. nitrat e compounds which are ions the opponent is identified on the wave number 1381 cm -1 (handayani et al, 2013). the organometallic compound [cr3o(ooch)6(h2o)3(no3)]. furthermore used as insertion on activated natural bentonite and its products will be applied as dye adsorbent of procion red. identification of natural bentonite and activated bentonite using ft-ir spectrophotometer, xrd, and xrf analysis natural bentonite is activated using two ways, the first is physical i.e. bentonite furnace at a temperature of 400o with the aim of expanding the surfacevof bentonite granules. the second process is chemically using sulphuric acid aim s to convert existing ca+ cations into ca-bentonite to h+ and released the ions of al, fe, and mg ions and im purities on the lattice structure so that the natural bentonite becomes active (sim amora et al., 2016). the result of natural bentonite the activated is then characterized using ftir spectrophotometer, xrd, and xrf analysis as presented in figure 2, figure 3 and table 1. figure 1. ft-ir spectra of the compound organometallic [cr3o(ooch)6(h2o)3](no3)] figure 2. ftir spectrum : (a) natural bentonite, (b) bentonite heating 400oc, (c)bentonite after acidification figure 2 can be divided into two regions: the main is in the range of wave numbers 300-1000 cm -1 denotes the area of identification inorganic compounds and span areas wave number 1000-4000 cm -1 shows the basis of organic uptake. identification of natural bentonite is determined by a hydroxy group caused by a molecule absorbed o-h at the surface of the octahedral layer and si-o-si coating groups tetrahedral (koestiari, 2014). the wave data of natural bentonite, bentonite after heating with a temperature of 400 ºc and bentonite after acidification can be seen on table 1. natural bentonite (d) indicates the presence of bentonite at the 5-6 diffraction peaks. mineral of montmorillonite was seen at the peak of 18 and silicate minerals at the peak of 20. on bentonite heating 400oc (e), bentonite is reduced because of the warming but silicate minerals and fixed montmorillonite vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 12 minerals. at the acidification bentone, a shifting mineral of montmorillonite residing on the peak of 25-26 and appear mineral illite on the peak of 19 . based on figure 7 is known that the largest diffraction appears at the corner region diffractio n 19.4°, 34.6°, and 20.8° located in the 2θ region indicating the presence mineral montmorillonite, silicate minerals, and mineral illite. the typical diffraction of all bentonite type indicates that bentonite has a high crystallinity. the results of xrd diffraction analysis shows the oxides present decreased the amount caused by thermal activatio n process and acid activation so the im purities are decreasing. this diffraction result is supported by data analysis quantitative of xrf that the natural bentonite is composed from mineral montmorillonite containing silica and alumina with the largest compositions that produce percentage of amount of al2o3 and sio2 metal oxides by 17% and 43.6%. the other m etal oxides are measured i.e. p2o5 of 0.71%, k2o of 0.2%, cao of 0.99%, tio2 of 1.87%, v2o5 of 0.11%, cr2o3 of 0.075%, mno of 0.15%, fe2o3 of 33.39%, nio of 0.87%, cuo of 0.15%, zno of 0.09%, re2o7 of 0.11, and eu2o3 of 0.2%. table 1. data of bentonite wave numbers of natural bentonite, heating bentonite and acidification bentonite compound wave number group natural bentonite 470.6 532.3 686.6 1635.6 3448.7 3626.1 v(si-o-si) v(al-o-si) v(si-o) v(o-h) v(h-o-h) v(o-h) heating bentonite 470.6 532.3 694.3 1635.6 3448.7 3695.6 v(v(si-o-si) v(al-o-si) v(si-o) v(o-h) v(h-o-h) v(o-h) acidification bentonite 470.6 532.3 694.3 1635.6 3448.7 3600.2 v(v(si-o-si) v(al-o-si) v(si-o) v(o-h) v(h-o-h) v(o-h) further characterization of natural bentonite and activat ed natural bentonite carried out using an xrd analyst is presented in figure 3. figure 3. xrd diffraction patterns for: (d) natural bentonite, (e) bentonite heating 400oc and (f) acid-activated bentonite activation on natural bentonite caused a decrease in the percentage value minor metal oxide. this corresponds to a function of physical activation that can degrade percentage of im purity on natural bentonite and eliminating some minor metal oxides. on the activation of natural bentonite using sulphuric acid (h2so4) also causes a decrease som e minor metal oxides are caused by the metal oxides contained in bentonite is bound to the h+ ion and causes layers between bentonite layers open. table 2. the data of percentage of metallic oxide using xrf the identification results of insertion of natural activated bentonite using spectrophotometer ftir, xrd and xrf natural bentonite is then activated inserted using organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] with addition of aquadest (h2o) and sodium hydroxide to form a suspension. natural bentonite is inserted with 4 comparisons bentonite: organometallic compounds (2.5: 1), (1: 1), (1: 2) and (1: 3) with a view to determine the optim al insertion bentonite. to identify the natural bentonite of the insertion , it has been done the characterization using ft-ir spectrophotometer, xrd analysis, and xrf analysis. ft-ir spectra obtained can be seen in figure 4, diffractogram xrd is presented in figure 5, and the results of the analysis xrf in table 2. figure 4. ftir spectrum of insertion bentonite with a ratio of 2.5: 1 (g); 1: 1 (h); 1: 2 (i); 1: 3 (j) figure 4 presents the functional group observed i.e. clusters of the compound organometallic [cr3o(ooch)6(h2o) 3 (no3)]. and bentonite groups are in the range of the wave number of 300-4000 cm -1. on comparison (2.5:1) indicates the presence cr-o vibration at the wave number of 670 cm -1 and also the formic acid ligands were shown by the vibrations, c-h, c-o, and o-h appear on the wave number of 2931,8-3448, 7 cm -1. on comparison (1:1) shows the vibration of cr-o at wave number of 700 cm -1, and vibration c-h, c-o, and o-h appear on the wave number of 2931,8-3448,7 cm -1. on comparison (1:2) cr-o at the wave number of 675 cm -1 and vibration c-h, c-o, and o-h appears at the wave number of 2931,8-3441 cm 1. in comparison (1:3) cr-o at the wave numbers of 675 cm -1 and c-h, c-o, and o-h vibrations appear on the wave number of 2931,8-3448,7 cm -1. ftir spectrum in figure 4 shows that all the comparisons the insertion process produces the ftir spectrum which does not differ significantly so to determine the optim al insertion process requires others supporting characterization data. bentonite inserted compound the organometallic is further characterized using xrd analysis that shows that at a ratio of vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 13 2.5: 1 (k) and 1: 1 (l) ratio is amorphous. comparison of 1: 2 (m) and a ratio of 1: 3 (n) produces diffraction that is not high tend to widen but still have crystallinity. the existence of diffraction that appears on region 2θ i.e. at 3-5o diffraction angle, 3,3-5o, 3,3-4,2o, 3,3-13,6o marks the typical peak on bentonite inserted by comparison (2.5:1), (1:1), (1:2), (1:3). based on the data xrd measurement results are known to be diffractio n most often appear at 4° diffraction angle, 3.0°, 5.0º, and 39° in the presence of minerals m ontmorillonite, silicate minerals, and minerals illite. according to syuhada (2008), the value of cation s exchange more than 1.0 will reduced the increasing of d-spacing. this matter due to the excess concentration of organometalli c compounds will cause the organometallic compound will be arranged within the bentonite. figure 5. identification of insertion bentonite with a ratio of 2.5: 1 (k); 1: 1 (l); 1: 2 (m); 1: 3 (n) using xrd analysis table 2. the composition of oxyde of the insrted bentonite sample al2o3 sio2 p2o5 k2o cao (%) (%) (%) (%) (%) (1:2) 2.7 6.7 0.34 0.33 (1:3) 2 4.1 0.35 0.30 sample nio cuo zno re2o7 yb2o3 nio cuo (%) (%) (%) (%) (%) (1:2) 1.0 0.17 0,06 1.0 0.17 (1:3) 1.0 0.17 0,06 1.0 0.17 sample tio2 v2o5 cr2o3 mno fe2o3 (%) (%) (%) (%) (%) (1:2) 0.42 76,28 1,1 9,64 76,28 1,1 9,64 76.28 76,28 1,1 9,64 1.1 76,28 1,1 9,64 9.64 76,28 1,1 9,64 (1:3) 0.27 82.28 1.2 6.4 82.28 1.2 6.4 82.28 82,28 1.2 6.4 1.2 82.28 1.2 6.4 6.44 82.28 1.2 6.4 samp so3 moo3 euo3 bi2o3 le (%) (%) (%) (%) (1:2) 1,2 (1:3) 0.95 1.3 different diffraction positions will signifies the influence of the constituent atom different bentonite, and that affecting the intensity of x-ray diffraction. this analysis is in accordan ce with that analysis generated by infrared spectra states the existence of o-h strain from the structure silicate. thus the differen ce between the distance the field is caused by the number of atoms and the position of the atom in the cell. this also proposed by tomul and balci (2007)which states that the number of species insertion causes influence on distance interlayer and the strength of the crystal structure changed after physical activation. this crystal structure is related to the number electrons contained at a particular point and known as the intensity (i)(ismunandar, 2006). based on ftir data and analysis xrd, it is seen that the little shifting of diffraction angle on the comparison (2.5:1) and (1:1) so it cannot yet determine optim al ratio. therefore select ed comparison (1:2) and (1:3) are performed an optim um shift diffraction angle and subsequently characterized using xrf analysis. the data are presented in table 2 showing the results xrf analysis on inserted bentonite organometallic compound [cr3o(ooch)6(h2o)3(no3)] by ratio (1:2) and (1:3) with cr2o3 metal oxide increase of 76.29% to 82.28% so on the comparison 1:3 insertion process of organometallic compound to in bentonite works perfectly because it has the highest percentage. through xrf analysis data can be determined the result of insertion of bentonite with the organometalli c compound [cr3o(ooch)6(h2o)3 (no3)] which is optim al in comparison (1:3) to be applied as the adsorbent of procion red. effect of adsorption time of colour substance procion red using activated and inserted bentonite organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] the influence of tim e of adsorption of procion red is shown in figure 6. figure 6. effect of dye adsorption of procion red tim e using activated bentonite and inserted bentonite figure 6 shows when the tim e of adsoprtion increases, it will also increase the procion red dye adsorbed. this is due to the longer the tim e of collision between adsorbents with adsorbate then the more adsorbate can adsorb by adsorbents. inserted bentonite has a quick adsorption tim e with the substance procion red adsorbed for 29.54 mg/l compared with activat ed bentonite at 22.90 mg/l. this matter due to inserted bentonite has a distance between layers so it can quick adsorb the very procion red dye. the data of influence tim e of adsorption is used to determine kinetic parameters i.e. the absorption rate. the adsorption rate data is calculated with the langmuir-hinshelwood equation. vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 14 data calculation of kinetic parameters presented in figure 7 and 8. based on the langmuir-hinshelwood, the rate of adsorption constant can be calculated and presented in table 4. the correlation coefficient obtained shows the existence of linear line equations. equation of line with correlation coefficient (> 0.9) indicates that the adsorption kinetics the procion red satisfies the kinetics equation langmuir-hinshelwood. table 3 shows the rate of adsorption rate for activat ed bentonite greater than inserted bentonite. this is due to activated bentonite has a spacing between layers very small so when the adsorbate dye procion red entry more easily filled compared to the inserted bentonite has a greater spacin g between layers because it has been inserted organometalli c compound so that the activated bentonite is more reactive than on insertion bentonite. figure 7. kinetic parameters of adsorption of substances procion red by activated bentonite figure 8. kinetic parameters of adsorption of substances procion red by inserted bentonite effect of temperature and concentration of procion red, and determination of thermodynamic parameters on the activated and inserted bentonite effect of temperature on adsorption of procion red is presented in figure 9 and 10. from the figures 9 and 10, it can be sen that the higher temperature and concentration (mg/l) will make the procion red adsorbed also increase. figure 9 shows between procion red. but its also seen that the increasing of temperature did not causes the amount procion red absorbed procion too significantly. in figure 10, the difference of point (x, y) is significant compared to figure 9. adjacent as in activat ed bentonite. the explanation of this phenomenom should be from the macro cations inserted in the deep layer of bentonite. the macro cations trapped the procion red inside of the adsorbent and the it is difficult to release it again. the value of thermodynamic parameters of adsorption is listed in table 4 and 5. table 4 shows that the maxim um capaci t y of procion red dye adsorption (b) and energy of adsoprtion (e) on some concentrations by bentonite are activated and inserted bentonite shows irregular increases along increased tem perature. the adsorption process occurs at varying temperatures is in the endothermic conditions. table 5 shows the δh value of adsorption of procion red by activated and inserted bentonite has decreased irregularl y contrary with increasing concentration of varied procion red. the δs value of adsorption of procion red by activated and inserted bentonite shows the order of irregularity that occurs on the adsorption process. the adsorption process with the highest entropy is occured on activated bentonite with a concentrat i o n of 0.5 mg/l i.e. 278.99 kj/mol, and in inserted bentonite at 0.5 mg/l of concentration reached 315.08 kj / mol. table 3. the adsorption rate values for activated bentonite and inserted bentonite adsorbent rate of adsorption (min-1) r2 activated 0.0048 0.9537 inserted 0.004 0.9759 figure 9. effect of temperature and concentration on adsorption of procion red using activated bentonite figure 10. effect of temperature and concentration on adsoprtion of procion red using inserted bentonite effect of initial ph 0n adsorption of dyestuffs procion red using activated and inserted bentonite effect of ph on dye adsorption procion red by activated and inserted bentonite is presented in figure 11. procion red dye adsorption process by activated bentonite has an initial ph of 4. after added hydrochloric acid (hcl), the ph goes down to 3 and the number of procion red adsorpted increased. this phenomenon characterized by a colour change of procion red vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 15 to become a pale red. on process addition of sodium hydroxide (naoh), ph incresed to 8, 9, 10 and 11, and it caused a decreas e in the number of procion reds adsorbed. it is marked with a colour change to dark red. figure 11. effect of ph on procion red adsoprtion table 4. thermodynamic parameters of procion red adsorption by activated and inserted bentonite adsorbent temp. (oc) b (mg/g) e (kj/mol) activated bentonite 30 55.86 3.1 40 34.36 15.77 50 39.32 12.15 60 45.24 0.03 70 72.99 7.24 inserted bentonite 30 -10.99 -9.32 40 -7.74 -32.37 50 -6.45 -6.25 60 -4.75 17.05 70 -8.22 5.36 table 5. the values of r, δh, δs with variations concentrat i o n of activated bentonite and bentonite inserted adsor bent conc r2 δh δs activate d bentonit e 0.5 0.9395 94413.78 278.99 10 0.9987 51494.42 160.65 25 0.7998 30274.59 84.88 40 0.9527 22244.1 59.86 60 0.983 17651.45 44.91 inserted bentonit e 0.5 0.8362 10572.82 315.08 10 0.7825 44962.94 127.23 25 0.9284 34355.94 90.19 50 0.9597 36281.46 94.106 100 0.9166 52458.84 135.99 in the adsorption process of procion red by inserted bentonite, it has an initial ph of 8.48 with the amount procion red adsorbed at 20.24 mg/l. when it added with hydrochlo ri c acid (hcl) at ph 7, 6, 5, it caused a decrease the number of procion red absorbed. at ph 4. 3 amount of red absorbed procion return to increased indicated by pale red colour. contrary to activated bentonite process, on inserted bentonite adsorbent shows the increasing in the amount of procion red absorbed at ph 9, 10 and 11, followed by the colour changes becomes dark red when it added with sodium hydroxide (naoh). the existence of change of colour on the procion red adsorbed by both activated or inserted bentonite either on an acidic or base atmosphere is based on the effective ph of the procion red i.e. at ph 3 5. when the atmosphere is acid then the colour will change to pale red, otherwise in an alkalin e atmosphere the mixture will be a dark red. interaction study of procion red inserted organometallic compounds [cr3o(ooch)6(h2o)3 (no3)] using ft-ir spectrophotometer the ft-ir spectrum of activated bentonite at before and after adsorbing procion red dye is presented in figures 12 and 13. figure 12. ft-ir spectrum of activated before (a) and bentonite inserts (b) after absorbing the procion red. figure 13. the ft-ir spectrum of bentonite inserted organometallic compounds before (a) and after (b) adsorb the procion dye red vibration of functional groups contained in procion red dye appears in a specific wave. figure 12 shows changes in the ftir spectrum . the wave number between activated bentonite before and after absorbing the dyestuff procion red that is not much different. on the wave number 470 cm -1, it represent s vibration of si-o-si and s=o of the dye procion red with sharp intensity. the bonding of activated bentonite after adsorption procion red appears on the wave number 1635.6 cm -1 indicates typical n = n vibration in procion red. n-h vibrations are clogged on the cluster functional procion red appears on number 3615 cm -1. figure 13 shows the change of the inserted bentonite spectrum after adsorb the procion red dye. it is seen the vibration bonds of clusters functional procion red appears at 1635 cm -1 that shows the ribbon absorption for n = n indicating the presence azo group (widjajanti et al, 2011). vitanesa et al. / science and technology indonesia 2(1) 2017:9-16 @2017 published under the terms of the cc by nc sa 4.0 license 16 co nclusion bentonite inserted with an organometallic compound [cr3o(ooch)6(h2o)3 (no3)] which is characteriz ed by ft-ir spectrophotometer indicates an insertion process but it has not yet show optim al result so characterization is also done using xrd. the xrd result shows optim al insertion process in comparison (1: 2) and (1: 3) with angular shifts diffraction of 5.00, and 39° of initial activated bentonite at 20.8o. on inserted bentonite, it is seen diffraction not high and tends to widened but still has crystallinity. to support of process success insertion carried out advanced characterization using xrf analysis. it shows optim ized inserted bentonite process on comparison (1: 3) with the percentage of oxide metals of 82.28%. adsorption of procion red dye using bentonite inserted compound organometallic [cr3o(ooch)6(h2o)3(no3) ] studied using kinetic parameters, thermodynamics, and ph. adsorption of dyestuff procion red with activated bentonite has an absorption rate of 0.0048 min-1 while on inserted bentonite has the rate of 0.004 min-1. parameter thermodynamic adsorption by both adsorbents with temperature variations shows the increasing and the decreasing, and as well with the value of adsorption energy (e). the highest value of energ y adsorption at a temperature of 60oc for 72.99 kj/mol and at the inserted bentonite is 17.05kj/mol at a temperature of 60oc. on ph 5 there is an increasing in the number of procion red adsorbed by activated bentonite i.e. 25.32 mg/l and on inserted bentonite amount of red absorbed procion of 33.38 mg/l at ph 11. acknowledgement we thanks sriwijaya university for support this research through “hibah pnbp 2016” to a.l. references altunlu, m. and yapar, s. 2007. effect of oh-/al+3 and al+3/clay ratios on the adsorption properties of al-pillared bentonites. colloids and surf aces a: physicochemical 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hence, it has been developed in numerous ways. nevertheless, all of these results are reliant on the existence anduniqueness of a fp on some suitable space. because the fp problem could not have a solution in the case of nonself-mappings,the idea of the best proximity point (briefly bpp) is offered to approach the best solution. this paper investigates the existenceand uniqueness of the bpp of nonself-mappings in fuzzy normed space(briefly fnspace) to arrive at the best solution. followingthe introduction of the definition of the bpp, the existence, and uniqueness of the bpp are shown in a fn space for diverse fuzzyproximal contractions such as 𝔅�̃� fuzzy proximal contractive mapping and 𝔅h 𝔍h fuzzy proximal contractive mapping. keywordsfuzzy normed space, fuzzy proximal contractive, best proximity point, fuzzy banach space, cauchy sequence received: 18 december 2022, accepted: 23 march 2023 https://doi.org/10.26554/sti.2023.8.2.298-304 1. introduction one of the most important branches of modern mathematics is functional analysis. it is crucial in the theory of differential equations, particularly partial differential equations, representation theory, and probability, as well as in the study of numerous properties of different spaces such as normed space, hilbert space, banach space, and others (sabri and ahmed, 2023; nemah, 2017; eiman and a.mustafa, 2016; zeana and k.assma, 2016; dakheel and ahmed, 2021). numerous applications in mathematics and allied fields, such as inverse problems, are made possible by the well-known banach fp theorem (banach, 1922) , which concerns the presence and uniqueness of fp of self-mappings defined on a complete metric space (see (lin et al., 2018; zhang and hofmann, 2020)). the banach fp theorem has drawn many academics to expand the reach of metric fp theory because of its wide variety of applications (see (abbas et al., 2012; latif et al., 2015; mustafa et al., 2014)). on the other hand, if u and v are both nonempty subsets of (l; d) (where (l; d) is a metric space), consequently in the situation of a mapping t u→ v, it is possible that there is not a point u in u such that u=tu: where d is the distance between u and v. in these kinds of instances, it is preferable to locate an element u in u such that the distance between u and t u is as low as possible. if there is such an element u in u, consequently it represents the bpp of t. zadeh developed and examined the concept of a fuzzy set in his groundbreaking research in zadeh (1978) . the exploration of fuzzy sets has resulted in the fuzzification of several distinct mathematical ideas. it has potential applications in many different domains. kramosil and michálek (1975) initially presented the idea of fuzzy metric spaces. then the concept of fuzzy metric spaces was modified by george and veeramani (1994) . numerous articles have been published on fuzzy metric spaces (hussain et al., 2020; paknazar, 2018; gregori et al., 2020; zainab and kider, 2021 sabri, 2021; li and zhang, 2023). fn space was subsequently introduced in different methods by a large number of other mathematicians. fn space has been the topic of a considerable number of publications; for instance, see (miheţ and zaharia, 2014; sabri and ahmed, 2022; kider and kadhum, 2019; sharma and hazarika, 2020; sabre, 2012; konwar and debnath, 2023; sabri and ahmed, 2023; raghad, 2021). examining the presence and uniqueness of the bpp in a fn space is the goal of this work, offering an approach to expand and fuzzify results in normed spaces. to that end, three theorems are presented that demonstrate the presence and uniqueness of the bpp under various circumstances. in addition, an example is provided to demonstrate the use of the main theorem. https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.2.298-304&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.2.298-304 sabri et. al. science and technology indonesia, 8 (2023) 298-304 2. experimental section 2.1 preliminaries this section defines the terminology and outcomes which is going to be utilized throughout the paper. materials : 2.1.1 definition 3.1 nadaban and dzitac (2014) let d represent the vector space over the field r. a triplet (d, fn , ⊗) is termed a fn space where ⊗ is a t-norm and fn represent a fuzzy set on d×r satisfies the requirements below for every p,q∈d: (fn1)fn (p, 0) = 0, (fn2)fn (p, 𝜏) = 1∀ > 0 if and only p = 0 (fn3)fn (rp, 𝜏) = fn ( p, 𝜏 |r | ) , ∀r ∈ r, where r ≠ 0 and 𝜏 ≥ 0 (fn4)fn (p, 𝜏) ⊗ fn (q, s) ≤ fn (p + q, 𝜏 + s)∀𝜏 ≥ 0 (fn5)fn (p, .)is the continuous for each p ∈ d and lim 𝜏→∞ fn (p, 𝜏) = 1 2.1.2 definition 3.2 bag and samanta (2003) consider (d,fn ,⊗) be a fn space. then 1. a sequence pn is called a convergent if limn→∞ fn (pnp, 𝜏) = 1;∀ > 0 and p ∈d. 2. a sequence pn is called cauchy if limn→∞ fn (pn+1pn, 𝜏) = 1;∀ > 0 and j = 1,2,... 2.1.3 definition 3.3 bag and samanta (2003) a fn space (d, fn ,⊗) is called complete if every cauchy sequence in d is convergent in d. in a fn space (d,fn ,⊗), sabri and ahmed (2022) presented the notion of fuzzy distance. consider ũ and ṽ be subsets of (d,fm,⊗) which are nonempty and ũ ◦ (𝜏), ṽ ◦ (𝜏) denoted by the following sets : ũ ◦ (𝜏) = { p ∈ u : fn (p − q, 𝜏) = na(ũ ,ṽ , 𝜏) for some q ∈ ṽ} ṽ ◦ (𝜏) = { q ∈ ṽ : fn (p − q, 𝜏) = na(ũ ,ṽ , 𝜏) for some p ∈ ũ } wherena(ũ ,ṽ , 𝜏) = sup { fn (p − q, 𝜏) : p ∈ ũ , q ∈ ṽ } 3. results and discussion in this section, the definition 𝔅�̃�fuzzy proximal contractive mapping and 𝔅h 𝔍hfuzzy proximal contractive mapping is presented, then our main results are proved. in a fuzzy metric space, guria et al. (2019) proposed the notion of bpp. in the following, the notion of the bpp in the framework of fn space is introduced. 3.1 definition 4.1 let (d, fn , ⊗) be a fn space and ũ, ṽ are nonempty subsets of d . an element p* ∈ ṽ is called the bpp of a mapping t:ũ→ ṽ if fn (p*-tp*, 𝜏)= na(ũ, ṽ , 𝜏) for all 𝜏 > 0 next, the definition of 𝔅�̃�fuzzy proximal contractive mapping is presented. consider 𝜓 represents the collection of all functions �̃�:[0,1] → [0,1], having the properties below: 1. �̃� is decreasing 2. �̃� is continuous 3. �̃� (`)= 0 if and only if ` = 1 3.2 definition 4.2 assume that (d, fn , ⊗) is a fn space and let ũ, ṽ subsets of d which are nonempty.let t ũ → ṽ be a mapping. then t 𝔅�̃� fuzzy proximal contractive mapping where �̃� ∈ 𝜓 if for all p,q,u,v ∈ ũ we have, fn (u − tp, 𝜏) = na(ũ ,ṽ , 𝜏) fn (u − tq, 𝜏) = na(ũ ,ṽ , 𝜏)  ⇒�̃�(fn (u − v, 𝜏)) ≤ 𝜗(𝜏)𝔅�̃�(p, q, 𝜏) (1) where 𝜗:(0,∞) →(0,1) is a function and 𝔅�̃� (p,q,𝜏) = max �̃�(fn (p-q,𝜏)) �̃�(fn (p-u,𝜏)) ⊗ �̃�(fn (p-u,𝜏)), �̃�(fn (q-u,𝜏)) 3.3 theorem 4.3 assume that (d, fn , ⊗) be a fuzzy banach space (brefily fb space) where ⊗ is min t-norm and let ũ, ṽ subsets of d (where ũ and ṽ closed). suppose ũ ◦ (𝜏) is non-empty and t : ũ → ṽ is nonself mapping fulfilling the following requirements: 1. t (ũ◦(𝜏)) ⊆ ṽ◦ (𝜏), ∀ 𝜏 > 0 2. t is 𝔅�̃� fuzzy proximal contractive mapping 3. if a sequence qn is in ṽ ◦ (𝜏) and p ∈ ũ such that fn (p-qn,𝜏)= nd (ũ,ṽ ,𝜏) as n → ∞ p ∈ ũ ◦ (𝜏), ∀ 𝜏 > 0 then t possesses a unique bpp. proof: consider p◦ in ũ ◦ (𝜏) since t (ũ ◦ (𝜏)) ⊆ ṽ (𝜏), there exists p1 ∈ ũ◦(𝜏) such that fn (p1-t◦,𝜏)=na (ũ,ṽ ,𝜏) ∀ > 0 the process is repeated, and we get a sequence pn in ũ◦(𝜏) fulfilling fn (pn − tp−1, 𝜏) = na(ũ ,ṽ , 𝜏) fn (pn+1 − tpn, 𝜏) = na(ũ ,ṽ , 𝜏) (2) if for any n◦ ∈ n, pn+1=pn, then according ton(2), is a bpp of t. consequently, suppose pn+1 ≠ pn for each n ∈ n. now for each 𝜏>0 and n ∈ n ∪ 0 define ln (𝜏) = fn (pn-pn+1, 𝜏). from (1) we get �̃�(ln(𝜏)) = �̃�(fn (pn−pn+1, 𝜏)) ≤ 𝜗(𝜏)𝔅�̃�(pn−1−pn, 𝜏) (3) where 𝔅�̃� (pn−1-pn′ , 𝜏) = max �̃� (fn (pn−1-pn′ , 𝜏)), �̃� (fn (pn−1-pn′ , © 2023 the authors. page 299 of 304 sabri et. al. science and technology indonesia, 8 (2023) 298-304 𝜏) ⊗ �̃� fn (pn-pn′ , 𝜏)), �̃� (fn (pn-pn+1, 𝜏) = max {�̃� (fn (pn−1-pn′ , 𝜏)),�̃� (fn (pn−1-pn′ , 𝜏) �̃� (fn (pnpn+1, 𝜏) } = max {�̃� (fn (pn−1-pn′ , 𝜏)), �̃� (fn (pn-pn+1, 𝜏)) } if max {�̃� (fn (pn−1-pn′ , 𝜏)), �̃� (fn (pn-pn+1, 𝜏))}= �̃� (fn (pn-pn+1, 𝜏)) then �̃� (ln)(𝜏)) ≤ 𝜗 (𝜏) �̃�(ln)(𝜏) < �̃�(ln)(𝜏)) but this a contradiction since 0<𝜗(𝜏)<1. hence �̃�(ln)(𝜏)) ≤ 𝜗(𝜏)�̃�(ln−1)(𝜏) < �̃�(ln−1)(𝜏)) therefore ln (𝜏) is increasing, so there is l(𝜏) ∈ (0,1] with limn−∞ ln(𝜏) = l(𝜏) ∀𝜏> 0. now, it will be established that l(𝜏)=1; ∀𝜏> 0 suppose there is 𝜏◦ > 0 with 0 <l(𝜏◦) < 1. then �̃�(l)(𝜏◦)) = lim n−∞ �̃�(l)(𝜏◦)) ≤ 𝜗(𝜏◦) lim n−∞ �̃�(ln−1)(𝜏◦)) ≤ 𝜗(𝜏◦) lim n−∞ �̃�(l)(𝜏◦)) ≤ �̃�(l)(𝜏◦)) a contradiction. thus, l(𝜏)=1 and conclude that lim n−∞ ln = 1 (4) after that, in order to demonstrate that pn is a cauchy sequence. consider pn is not cauchy. consequently there is ϶ ∈(0,1) such that ∀k∈n, there are m(k),n(k) ∈n with mk > nk ≥ k and fn (pmk − pnk, 𝜏◦) ≤ 1− ϶ where𝜏◦ > 0 (5) suppose m(k) is the smallest number that is larger than n(k), and meets the equation (5) fn (pmk−1 − pnk, 𝜏◦) > 1− ϶ which indicates 1− ϶ ≥ fn (pmk − pnk, 𝜏◦) ≥ fn (pmk − pmk−1, 𝜏◦) ⊗ fn (pmk−1 − pnk, 𝜏◦) > fn (pmk − pmk−1, 𝜏◦) ⊗ 1− ϶ as a result, we find lim k−∞ fn (pmk − pnk, 𝜏◦) = 1− ϶ (6) now from fn (pmk−1 − pnk, 𝜏◦) ≥ fn (pmk+1 − pmk, 𝜏◦) ⊗ fn (pmk − pnk, 𝜏◦) ⊗ fn (pnk − pnk+1, 𝜏◦) taking limit as k → ∞, we arrive lim k−∞ fn (pm(k)+1 − pn(k)+1, 𝜏◦) ≥ 1− ϶ (7) now, combining the results of (4) and (6), we yield fn (pmk − pnk, 𝜏◦) ≥ fn (pmk − pmk+1, 𝜏◦) ⊗ fn (pmk+1 − pnk+1, 𝜏◦) ⊗ fn (pnk+1 − pnk, 𝜏◦) thus, it follows lim k−∞ fn (pmk+1 − pnk+1, 𝜏◦) = 1− ϶ additionally fn (pmk − pnk, 𝜏◦) ≥ fn (pmk − pmk+1, 𝜏◦) ⊗ fn (pmk+1 − pnk+1, 𝜏◦) ⊗ fn (pnk+1 − pnk, 𝜏◦) indicates lim k−∞ fn (pmk − pnk+1, 𝜏◦) ≥ 1− ϶ likewise, lim k−∞ fn (pnk − pmk+1, 𝜏◦) ≥ 1− ϶ now fn (pmk+1 − tpmk, 𝜏) = na(ũ ,ṽ , 𝜏) fn (pnk+1 − tpnk, 𝜏) = na(ũ ,ṽ , 𝜏) (8) indicates �̃�(fn (pmk+1 − pnk+1, 𝜏) ≤ 𝜗(𝜏◦)𝔅�̃�(pmk, pnk, 𝜏◦) ≤ 𝜗(𝜏◦)max { �̃�(fn (pmk − pnk, 𝜏◦)�̃�(fn (pmk, pmk+1, 𝜏◦) ⊗ (fn (pnk − pmk+1, 𝜏)�̃�(fn (pnk, pnk+1, 𝜏◦)) } as k goes to ∞ in above, we obtain �̃�(1− ϶) ≤ 𝜗(𝜏◦)max { �̃�(1− ϶), �̃�(1 ⊗ (1− ϶)), �̃�(1) } = 𝜗(𝜏◦)�̃�(1− ϶) if �̃� (1-϶) = 0 then ϶=0 but this contradiction. if ˜𝜓(1− ϶) > 0then�̃�(1− ϶) ≤ 𝜗(𝜏◦)�̃�(1− ϶) < �̃�(1− ϶) a contradiction since 0<𝜗(𝜏◦)<1 therefore pn is a cauchy. because (d,fn ),⊗) is complete then pn converges to p* ∈ d, lim n−∞ fn (pn − p∗, 𝜏) = 1 (9) furthermore, © 2023 the authors. page 300 of 304 sabri et. al. science and technology indonesia, 8 (2023) 298-304 na(ũ ,ṽ , 𝜏) = (fn (pn+1 − tpn, 𝜏)(by equation 3) ≥ fn (pn+1 − p∗, 𝜏) ⊗ fn (p∗ − tpn, 𝜏) (applying condition(fn4)) ≥ fn (pn+1 − p∗, 𝜏) ⊗ fn (p∗ − pn+1, 𝜏) ⊗ tpn, 𝜏) (applying(fn4)) = fn (pn+1 − p∗, 𝜏) ⊗ fn (p∗ − pn+1, 𝜏) ⊗ na(ũ ,ṽ , 𝜏) which indicates na(ũ ,ṽ , 𝜏) ≥ fn (pn+1 − p∗, 𝜏) ⊗ fn (p∗ − tpn, 𝜏) ≥ fn (pn+1 − p∗, 𝜏) ⊗ fn (p∗ − pn+1, 𝜏) ⊗ na(ũ ,ṽ , 𝜏) using limit as n→∞ in the preceding inequality, the following result is obtained: na(ũ ,ṽ , 𝜏) ≥ 1 ⊗ fn (p∗ − tpn, 𝜏) ≥ 1 ⊗ 1 ⊗ na(ũ ,ṽ , 𝜏) that is, lim n−∞ fn (p∗ − tpn, 𝜏) = na(ũ ,ṽ , 𝜏) (10) now, to demonstrate that t has a bpp. note that (c) and (9) imply p*∈ ũ◦ (𝜏) and hence tp*(ũ◦ (𝜏)). t(ũ◦(𝜏)) ⊆ ṽ◦ (𝜏) assures the existence of ` ∈ ũ◦ (𝜏) for which fn ( ` − tp∗, 𝜏) = na(ũ ,ṽ , 𝜏) (11) we claim that `=p*. contrary to this, suppose that `≠p* by (1), (2), and (11), obtain �̃� (fn (`-pn+1, 𝜏)) ≤ 𝜗 (𝜏) 𝔅�̃� (pn-p∗, 𝜏) ≤ 𝜗(𝜏)max { �̃�fn (pn − p∗, 𝜏)�̃�(fn (pn − `, 𝜏)⊗ fn (p∗ − `, 𝜏))�̃�(fn (p∗ − pn+1, 𝜏)) } employing limit as n approaches to ∞ in the above equation, one obtain �̃� fn ( ` − p∗, 𝜏) ≤ 𝜗(𝜏)max { �̃�(fn (p∗ − p∗, 𝜏) �̃�fn (p∗ − `, 𝜏)) ⊗ (fn (p∗ − `, 𝜏)), �̃�(fn (p∗ − p∗, 𝜏) } ≤ 𝜗(𝜏)�̃�(fn (p∗ − `, 𝜏)) < �̃�(fn (p∗ − `, 𝜏)) a contradiction 0<𝜗(𝜏)<1. therefore, `=p*and as a result fn (p∗-`,𝜏)=na (ũ, ṽ , 𝜏) thus p∗ is the bpp of t. if 𝛼 is another bpp of t with 𝛼≠p∗, then 0< (fn (p∗-𝛼, 𝜏))<1 and fn (p∗tp∗, 𝜏) = na(ũ, ṽ , 𝜏) and fn (𝛼t𝛼, 𝜏) = na(ũ, ṽ , 𝜏) �̃� fn (𝛼 − p∗, 𝜏) ≤ 𝜗(𝜏)𝔅�̃�(𝛼 − p∗, 𝜏) ≤ 𝜗(𝜏)max { �̃�(fn (𝛼 − p∗, 𝜏)�̃�(fn (𝛼 − 𝛼, 𝜏)⊗ fn (p∗ − 𝛼, 𝜏))�̃�(fn (p∗ − p∗, 𝜏)) } = 𝜗(𝜏)�̃�(fn (𝛼 − p∗, 𝜏) < �̃�(fn (𝛼 − p∗, 𝜏) a contradiction. thus the bpp is unique. 3.4 example 4.4: let d = r. suppose fn :d ×r→[0,1] is a fuzzy norm, defined by: fn ( p,𝜏)= 𝜏 𝜏+p ; ∀p ∈ d 𝜏>0, where ||p||: r→[0,∞) with ||p||=|p|. let ũ= {1,2,3,4,5} and ṽ = {6,7,8,9,10} so that na(ũ, ṽ , 𝜏) = supfn (p-q,𝜏): p ∈ũ, q ∈ũ = 𝜏𝜏+1 define d : ũ→ṽ by t(p) = { 6 i f p = 5 p + 5 otherwise we have ũ◦𝜏=5 andṽ◦𝜏=6, t ⊆ṽ◦𝜏 since fn (`-tp,𝜏)= na(ũ, ṽ , 𝜏) = 𝜏 𝜏+1 implies (u,p)=(5,5) or (u,p)=(5,1) now, let �̃� defined by �̃� (`)=1-` for each `∈[0,1]. then from (1), we have �̃�(fn (u-𝜗,𝜏) ≥ 𝜗 (𝜏) 𝔅�̃� (p,q,𝜏) (fn (u − 𝜗, 𝜏) = 𝜏 𝜏 + ||u − v|| = 𝜏 𝜏 + |5 + 5| = 1 which implies �̃�(fn (u-𝜗,𝜏)=1(fn (u-𝜗,𝜏)=1-1=0 and this shows that �̃�(fn (u-𝜗,𝜏) ≤𝜗(𝜏) 𝔅�̃�(p,q,𝜏) hold for each p,q, u,v ∈ ũ and for all 𝜏 >0 and 𝜗(𝜏) ∈(0,1) .therefore, each of the requirements of theorem 4.3 are met, and there exists a uniquep∗∈ ũ such that fn (p∗-tp∗,𝜏)= na(ũ, ṽ , 𝜏) for all 𝜏 >0. in this example p∗=5 is a unique bpp. now if we assume that ũ◦ (𝜏) is a nonempty closed set, then we may reduce some requirements in theorem 4.3 as shown below. 3.5 theorem 4.5: assume that (d, fn , ⊗) is a fb space where ⊗ is min t-norm. suppose that ũ◦(𝜏) is a closed subset of d and t ũ →ṽ is a mapping meeting the following conditions: 1. t (ũ◦(𝜏)) ⊆ ṽ◦ (𝜏) for each 𝜏 > 0 2. there is a function �̃� ∈ 𝜓 for which 3. fn (u − tp, 𝜏) = na(ũ ,ṽ , 𝜏) fn (u − tq, 𝜏) = na(ũ ,ṽ , 𝜏) } (12) ⇒ �̃� (fn (u-v,𝜏)) ≤ 𝜗 (𝜏) 𝔅�̃� (p,q, 𝜏) © 2023 the authors. page 301 of 304 sabri et. al. science and technology indonesia, 8 (2023) 298-304 holds for each p,q,u,v ∈ ũ, and 𝜏>0, where 𝜗:(0,∞) →(0,1) is a function and 𝔅�̃�(p,q,𝜏)=max �̃�(fn (p,q,𝜏), �̃�(fn (p,q,𝜏) ⊗ (fn (p,q,𝜏), �̃�(fn (p,q,𝜏))) then t possesses a unique bpp proof : similar to the proof of theorem 4.3, construct a cauchy sequence pn in ũ◦ (𝜏). the sequence pn is convergent to some p∗ in ũ◦ (𝜏) because ũ◦ (𝜏) is a closed set, and the completeness of (d, fn , ⊗) guarantees this. the remainder of the proof is identical to the proof given for theorem 4.3. now the notion of 𝔅h 𝔍hfuzzy proximal contractive mapping is introduced as follows: 3.6 definition 4.6: let (d, fn , ⊗) be a fn space and let ũ,ṽ nonempty subsets of d. assume that t:ũ→ṽ is a given mapping. then t is termed as 𝔅h 𝔍hfuzzy proximal contractive mapping if for each p,q,u,v ∈ũ and 𝜏>0 we have, fn (u − tp, 𝜏) = na(ũ ,ṽ , 𝜏) fn (u − tq, 𝜏) = na(ũ ,ṽ , 𝜏) } ⇒ (fn (u − v, 𝜏)) ≥ 𝔍h(p, q, 𝜏) + 𝔅h(p, q, 𝜏) (13) where h:i→i with h(`)>0 for each ` ∈ (0,1] and 𝔅h (p,q,𝜏)= min { h(p-q,𝜏), (fn (p-u,𝜏) ⊗ fn (p-u,𝜏), hfn (p-𝜗,𝜏))} 𝔍h (pq,𝜏) + {fn (p-q,𝜏),fn (p-u,𝜏)} the next theorem employs a different contraction condition than the previous results. 3.7 theorem 4.7: assume that (d, fn , ⊗) is a fb space where ⊗ is min t-norm and let ũ,ṽ closed and nonempty subsets of d where ũ◦𝜏 is non-empty. let t ũ→ṽ be nonself mapping meeting the following conditions: 1. t (ũ◦(𝜏)) ⊆ ṽ◦ (𝜏) 2. t 𝔅h 𝔍h fuzzy proximal contractive mapping. 3. if sequence {qn} is in ṽ◦ (𝜏) and p ∈ ũ with fn (p-qn𝜏)= na(ũ, ṽ , 𝜏) as n → ∞ then p ∈ ũ◦ (𝜏) thent possesses a unique bpp. proof : consider p◦ in ũ◦(𝜏. since t (ũ◦(𝜏)) ⊆ ṽ◦(𝜏, there exists p1 ∈ ũ◦(𝜏) such that fn (p1-tp◦𝜏) = na(ũ, ṽ , 𝜏) : for each 𝜏 > 0 the process is repeated, and we get a sequence pn in ũ◦(𝜏) fulfilling fn (pn1 − tpn−1, 𝜏) = na(ũ ,ṽ , 𝜏) fn (pnk+1 − tpn, 𝜏) = na(ũ ,ṽ , 𝜏) (14) from (13) and (14) obtain, fn (pn-pn+1, 𝜏) ≥ 𝔍h (pn−1, pn,𝜏) 𝔅h (pn−1, pn,𝜏) ≥ min{fn (pn−1 − pn, 𝜏)fn (pn − pn, 𝜏) + minh {fn (pn−1 − pn, 𝜏)hfn (pn−1 − pn, 𝜏) ⊗ fn (pn − pn, 𝜏), fn (pn − pn−1, 𝜏)))} (15) ≥ fn (pn−1-pn, 𝜏)+min { h (fn (pn−1-pn,𝜏)), h (fn (pnpn+1,𝜏))} which implies fn (pn-pn+1,𝜏) ≥ fn (pn−1-pn,𝜏) that is {fn (pn-pn+1,𝜏)} is is increasing, so there is 𝔧(𝜏) ∈(0,1] with limn−∞ fn (pn+1-pn,𝜏) = 𝔧(𝜏) ∀ 𝜏 > 0 now, it will be established that 𝔧(𝜏)=1 for each 𝜏 > 0. suppose there is 𝜏◦> 0 such that 0 <𝔧 (𝜏◦) < 1. considering limit as n goes to ∞ in (15), then 𝔧 (𝜏 ◦) ≥j(𝜏◦)+minh(𝔧(𝜏◦)),h(1)} if min h(𝔧(𝜏◦ )),h(1) =h(𝔧(𝜏◦)) then obtain 𝔧(𝜏◦) ≤(𝔧(𝜏◦ ) + h(𝔧(𝜏◦ )) implies thath (𝔧(𝜏◦ )=0 and this is a contradiction. if minh𝔧(𝜏◦ )),h(1) =h(1) then obtain 𝔧(𝜏◦) ≥ 𝔧(𝜏◦)+h(1) implies that h(1)=0 and this is a contradiction. this demonstrates that for all 𝜏> 0, 𝔧(𝜏) = 1. after that, to demonstrate pn is a cauchy sequence. consider pn is not cauchy. then there is ϶ ∈ (0,1) such that ∀k∈n, there are m(k),n(k) ∈n with mk > nk ≤k and fn (pmk − pnk, 𝜏) ≤ 1− ϶ (16) suppose m(k) is the smallest number that is larger than n(k), that meeting (16), fn (pmk − pnk, 𝜏) > 1− ϶ in a manner analogous to the proof of theorem 4.3, get lim n−∞ fn (pmk − pnk, 𝜏) = 1− ϶, lim n−∞ fn (pmk+1 − pnk+1, 𝜏) = 1− ϶ lim n−∞ fn (pmk − pnk+1, 𝜏) ≥ 1− ϶, lim n−∞ fn (pnk − pmk+1, 𝜏) ≥ 1− ϶ from (14) we get fn (pmk+1 −tpmk, 𝜏◦) = na(ũ ,ṽ , 𝜏◦)and fn (pnk+ −tpnk, 𝜏◦) = na(ũ ,ṽ , 𝜏◦) hence, (13) implies fn (pmk+1 − pnk+1, 𝜏◦) ≥ 𝔍h(pmk, pnk, 𝜏◦) + 𝔅h(pmk, pnk, 𝜏◦) ≥ min{fn (pmk −tpnk, 𝜏◦), fn (pnk −tpmk+1, 𝜏◦)} + min{h(fn (pmk − pnk, 𝜏◦)) © 2023 the authors. page 302 of 304 sabri et. al. science and technology indonesia, 8 (2023) 298-304 if k tends to ∞ in above inequality, one obtains 1-϶ ≥(1-϶)+min {h(1-϶) h(1)} thus 0≥ min {h(1-϶) h(1)} then, either h(1-϶)=0 or h(1)=0 but this is in both cases a contradiction, therefore pn is a cauchy. because (d,fn ,⊗) is complete then pn converges to p* ∈ d, lim n−∞ fn (pn − p∗, 𝜏) = 1f oreach𝜏 > 0 (17) now to demonstrate that t has bpp. like theorem 4.3, obtain p* ∈ ũ◦(𝜏). as (ũ◦(𝜏)) ⊆ ṽ◦(𝜏) assures the existence og ` ∈ũ◦(𝜏) fn ( ` −tp∗, 𝜏) = na(ũ ,ṽ , 𝜏) (18) we claim that `=p∗. contrary to this, suppose that `≠p∗ by (14) and (18), obtain fn (pnk+1 − `, 𝜏) ≥ 𝔍h(pn, p∗, 𝜏) + 𝔅h(pn, p∗, 𝜏 ≥ min{fn (pn − p∗, 𝜏), fn (p∗ − pn+1, 𝜏)} + min{h(fn (pn − p∗, 𝜏)), h(fn (pn − pn+1, 𝜏)⊗ (fn (p∗ − pn+1, 𝜏), h(fn (p∗ − `, 𝜏) using limit as n approaches to ∞ in above inequality, one gets fn (p∗ − `, 𝜏) ≥ 1 + min{h(1)fn (p∗, `, 𝜏))} so1 ≥ fn (p∗ − `, 𝜏) ≥ 1, which impliesfn (p∗ − `, 𝜏) = 1, that is` = p∗andfn (p∗ −tp∗, 𝜏) = na(ũ ,ṽ , 𝜏) to demonstrate the uniqueness, assume 𝛼 is another bpp of t such that 𝛼≠p∗, that is 0< fn (p∗ − 𝛼, 𝜏) < 1for𝜏 > 0asfn (p∗ −tp∗, 𝜏) = na (ũ ,ṽ , 𝜏)andfn (𝛼 −t𝛼, 𝜏) = na(ũ ,ṽ , 𝜏) hence, from (13) we obtain fn (p∗ − 𝛼, 𝜏) ≥ 𝔍h(p∗, 𝛼, 𝜏) + 𝔅h(p∗, 𝛼, 𝜏) ≥ min{fn (p∗, 𝛼, 𝜏), fn (𝛼, p∗𝜏)} + min{h(fn (p∗, 𝛼, 𝜏)), h(fn (p∗, p∗, 𝜏)⊗ (fn (𝛼, p∗, 𝜏), h(fn (𝛼, 𝛼, 𝜏)} (fn (p∗, 𝛼, 𝜏) + min{h(fn (p∗, 𝛼, 𝜏))h(1)} therefore (fn (p∗, 𝛼, 𝜏) ≥ (fn (p∗, 𝛼, 𝜏) + min{h(fn (p∗, 𝛼, 𝜏))h(1)} (19) which implies h fn (p∗,𝛼,𝜏)=0 or h which is in both cases a contradiction as h(`)>0 for each ` ∈ (0,1]. thus fn (p∗,𝛼,𝜏)=1 and so p∗=𝛼. 4. conclusion the bpp theorem for various non-self fuzzy contractive mapping types such as 𝔅hfuzzy proximal contractive mapping and 𝔅h 𝔍hfuzzy proximal contractive mapping in a fn space is established in this study. an example is presented to show the significance of the results that were obtained. the generalizations of these kinds of contraction mappings and studies of their applications in the fn space needs more investigation in upcoming work. 5. acknowledgment i would like to convey my profound appreciation to the reviewers of this work and the publishers of the "science and technology indonesia journal" for presenting me with this splendid opportunity. references abbas, m., v. parvaneh, and a. razani (2012). periodic points of t-ciric generalized contraction mappings in ordered metric spaces. georgian mathematical journal, 19(4); 597– 610 bag, t. and s. samanta (2003). finite dimensional fuzzy normed 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(1978). fuzzy sets as a basis for a theory of possibility. fuzzy sets and systems, 1(1); 3–28 zainab, a. and j. kider (2021). the hausdorff algebra fuzzy distance and its basic properties. engineering and technology journal, 39(7); 1185–1194 zeana, z. j. and k.assma (2016). data dependence result and stability of picard-s iteration scheme for approximating fixed point of almost contraction mappings. international journal of advanced research, 4(5); 760–763 zhang, y. and b. hofmann (2020). two new non-negativity preserving iterative regularization methods for ill-posed inverse problems. inverse problem image, 2(15); 229–256 © 2023 the authors. page 304 of 304 introduction experimental section preliminaries definition 3.1 15 definition 3.2 2 definition 3.3 2 results and discussion definition 4.1 definition 4.2 theorem 4.3 example 4.4: theorem 4.5: definition 4.6: theorem 4.7: conclusion acknowledgment research article http:sciencetechindonesia.com science & technology indonesia p-issn: 2580-4405 e-issn: 2580-4391 sci. technol. indonesia 3 (2018) 45-48 © 2018 the authors. production and hosting by arts publishing in association with indonesian science and technology society. this is an open access article under the cc-by-nc-sa license. article history: received 24 november 2017; revised 16 january 2018; accepted 16 january 2018 http://doi.org/10.26554/sti.2018.3.1.45-48 diversity of cu and total cr metals in surface water and sludge of textile wastewater from tuan kentang village seberang ulu i sub district palembang mirza firdyah astari1, adipati napoleon2, risfidian mohadi3, 1environtmental management departement, graduate school of sriwijaya university 2 faculty of agriculture, sriwijaya university 3 department of chemistry, faculty of mathematics and natural science, sriwijaya university *corresponding author e-mail: mirza@student.pps.unsri.ac.id abstract nowadays, the production of rainbow fabric as a traditional fabric of palembang city has been grown rapidly. commonly, the waste water as the by-product of rainbow fabric production is discharged directly to domestic channels without any previous waste water treatment. this research was aimed to evaluate the presence of cu and total cr heavy metal in the area of rainbow fabric industrial center in tuan kentang village, sebrang ulu i sub distric, palembang. the cu and total cr polluted in the collected wastewater sample was analyzed by using atomic adsorption spectrometry method with wet destruction technique. the results indicated that the area of tuan kentang villages is contributing metal contaminants distribution and accumulation to nature. keywords: textile, waste water, heavy metal 1. introduction the growing interest of the community to develop and maintain the values of customs and traditions is reflected in the development of cloths and fashion trends based on rainbow fabric (kain pelangi) as the traditional fabric in all societies. this is further supported by the local government by declaring the area of tuan kentang village district of seberang ulu i as the traditional fabric village and the center of rainbow fabric household industry. in the city of palembang. the production volume of rainbow fabric is increasing from last year so that operational activity will increase. but the problem arises, the waste water that is a by-product of this activity is discharged directly to domestic channels without any previous waste water treatment. dyestuffs are closely related to the content of metal contaminant ions and are the rest of the coloring process will be wasted and pollute the surrounding environment if not through the processing treatment (sasongko & tresna, 2010). the heavy metal content to be observed in this research is heavy metal ions of cu and cr total. although these two metals fall into the category of intermediate hazards in the long term, they can be carcinogenic (vodyanitskii, 2016). the nature of heavy metal contamination that comes out of the human activity and into the environment can dissolve and accumulate in the sediment and will continue to grow as time passes and the natural events are occurring at that location (wulan, thamrin, & amin, 2013). so the spread of cu and cr total metal ions is feared will be at risk of contaminating the life of environmental biota and ultimately this contaminant will affect human health even in the long term and far from the central of the pollution source. in order to evaluate the status of environmental conditions that actually occur in the location of research, this study was conducted to observe changes in conditions that occurred in industrial center of rainbow fabric in tuan kentang village at seberang ulu i subdistrict, palembang for 4 months. 2. experimental section the chemicals used in this research was reagent grade supplied from merck including sulfuric acid and hydrochloric acid. the water used for cu and cr standard solution was double distilled water. the rainbow fabric wastewater as the wastewater sample was collected from the surface water and the sludge at the source of the waste liquid which is the wastewater of residual immersion and kain pelangi rinsing, domestic channels prior to disposal site, domestic channels along the flow of waste water discharges, swamp where the final estuary of sewerage flow. subsequently, 5 (five) critical points as sampling points are observed from june to september 2017. the 5 (five) stations are show in table 1. this research was conducted from june to september 2017. sampling location was done in the residential area around the industrial center rainbow fabric in tuan kentang village at seberang ulu i subdistrict, palembang. analysis of heavy metal content of cu and cr using aas (atomic absorption spectrophotometer) conducted at the laboratory test of various commodities baristand industry palembang. the cu and total cr analymirza et al. 2018 / science & technology indonesia 3 (1) 2018: 45-48 46 sis on sludge using aqua regia destruction on hotplate at 180oc until the solution almost dry. then the sludge dried at 600c and it weighed as much as 2 grams for further treatment. after that sample destructed with 30 ml aqua regia (hno3 : hcl, 1 : 3), the result than cooled. after cooled, the sample was diluted with 100 ml distilled water. the sample solution then measured with atomic adsorption spectrometer (aas) shimadzu aa-7000 type 324 at 323,7 nm in order to determine the cu and cr content. the research method used in this study used descriptive analysis with quantitative analysis approach to water and sludge conditions in domestic channels at 5 stations with 4 different weather conditions. in each station, field testing is also done to see the condition of the location at the time of sampling. environmental quality parameters measured in the field include temperature, ph, turbidity, tss (total suspended solid), tds (total dissolve solid) and cod (chemical oxygen demand). the research design that will be carried out include: 1) study of literature related to research topic; 2) field observation; 3) determine the location of research; 4) determining objects and sampling points; 5) primary and secondary data collection (moisture and rainfall); 6) interview and data analysis; 7) calculation and comparison of data of total cr metal cation concentration in textile wastewater and the determination of metal cation contamination status based on south sumatera governor regulation no 8 the year 2012 on the quality standard of liquid waste for industrial, hotel, hospital, domestic and coal mining activities; regulation of the minister of environment of the republic of indonesia no 5 the year 2014 on wastewater quality standard; the quality standard of sludge (sediment) base on anzecc isqg-low 2010 8) calculation and comparison of data of cu metal cation concentration and textile wastewater field data on the surface water with the classification of iv class quality water based on south sumatera governor regulation no 16 the year 2005 on water allocation and river water quality standard; the quality standard of sludge (sediment) base on anzecc isqg-low 2010 3. results and discussion this observation result shows that the consentration of ions cu and total cr as below : the research result show that average of concentration cu in surface water is still under 0,2 mg/l although there are some data shows that upper than 0,2 mg/l such as in swamp area shows 0,2383 mg/l. it means that the location on under the craftsman house and swamp are the deepest depth than other area and upper from quality standard of south sumatera governor regulation no 16 the year 2005 on water allocation and river water quality standard that cu concentration on surface water is 0,2 mg/l. according to sujantoko and natakusumah (2003), the water depth is shallow if it smaller compare to width then there is only insignificant layer formed. because of it, if there is a quick current of water the layer taken along to the deepest depth area with it and will accumulate there. it shows in sampling point 4 that figure 1. map of research location on industrial center craft kain pelangi on tuan kentang village at seberang ulu i subdistrict, palembang table 1. observed critical points table sampling point position titik koordinat x y 1 a current 3°1’5,35” 104°45’ 22,4” 2 b current 3°1’5,23” 104°45’22,79” 3 end of ab current 3°1’5,63” 104°45’22,96” 4 filling under craftsman house and 3°1’5,48” 104°45’23,69” not flowing 5 swamp 3°1’5,31” 104°45’23,95” mirza et al. 2018 / science & technology indonesia 3 (1) 2018: 45-48 47 the highest cu concentration on sludge is 91,2174 mg/l that it is upper from the quality standard of sludge (sediment) base on anzecc isqg-low 2010 that cu concentration is maximum 65 mg/kg. in same case, figure 3. shows that the cr concentration on surface water and sludge has increase in sampling point 4 and 5. the highest cr concentration on sludge is 17,2563 mg/l and on surface water is 0,4888 mg/l. both is still under the quality standar of south sumatera governor regulation no 8 the year 2012 on the quality standard of liquid waste for industrial, hotel, hospital, domestic and coal mining activities; regulation of the minister of environment of the republic of indonesia no 5 the year 2014 on wastewater quality standard; the quality standard of sludge (sediment) base on anzecc isqg-low 2010 that cr concentration is maximum 80 mg/kg. the highest concentration in cu and total cr can be proof from cod value, turbidity value, tss value, and tds value. in sampling point 4 location, cod value shows 653,0 mg/l on june 2017 and 893,4 mg/l on august 2017. according to of south sumatera governor regulation no 8 the year 2012 on the quality standard of liquid waste for industrial, hotel, hospital, domestic and coal mining activities; regulation of the minister of environment of the republic of indonesia no 5 the year 2014 on wastewater quality standard, the cod concentration value must be under 150 mg/l. according to south sumatera governor regulation no 16 the year 2005 on water allocation and river water quality standard, the cod concentration value must be under 100 mg/l. base on these regulations, the cod concentrations value is not fulfill the government standart and will cause some damage too nature. as known before, cod is a need of oxygen for organic material describing anorganic material in nature. the high of concentration cod value shows that many anorganic material to describe by organic material. so the high of concentration cod value similar to high need of oxygen and similar to high concentration of anorganic material include cu and total cr concentration too. high concentration of anorganic material is also show in turbidity, tss and tds. the high value of turbidity can block the sunray entering the water channels so fotosintesis process not happen. the cause of it such as dye, organic material and anorganic material. according to rusdiansyah (2006), household water channels have unsteady non uniform properties, meaning that this channel has a flow influenced by the speed and direction that changes to space and time where the aeration process depends on the rate of flow rate so that the concentration of substance which is the parameter of water quality at each point of uneven flow field and the quality is always changing depending on fluctuations in the flow rate that occurs. in figure 2. and 3. there is trendline that shows the depth location on this area, but the concentration value of cu and total cr is not spread evenly. in order to find the most influential factors to the concentration of the content in the small industrial estate, researcher assume the datas on sample of september 2017 as the outlier data because it is extremely different. the percentage decrease of it shows as in table 2. and table 3 below. as shown in table 2. and table 3. that the decrease percentage of ions cu and total cr for sludge and surface water on june until september 2017 has differs markedly. base on this obser figure 2. cu concentration in sludge and surface water on june – september 2017 figure 3. total cr concentration in sludge and surface water on june – september 2017 table 2. decrease percentage of cu sampling point critical points jun 2017 versus sep 2017 jul 2017 versus sep 2017 aug 2017 versus sep 2017 sludge surface water sludge surface water sludge surface water 1 a current 824,374 100% 822,573 100% 858,143 100% 2 b current 511,546 488,184 321,026 3 end of ab current 702,075 646,678 619,975 4 filling under craftsman 957,181 949,575 919,795 house and not flowing 5 swamp 171,760 579,643 512,342 mirza et al. 2018 / science & technology indonesia 3 (1) 2018: 45-48 48 vation and calculation researcher assume that the reason for this decreases was the most influential factors to the concentration of the content in this area is the weather. 4.conclusion household water channels have unsteady non uniform properties, meaning that this channel has a flow influenced by the speed and direction that changes to space and time where the aeration process depends on the rate of flow rate so that the concentration of substance which is the parameter of water quality at each point of uneven flow field and the quality is always changing depending on fluctuations in the flow rate that occurs. so household water channel was not an ideal place to throw out the textile wastewater that not processed yet. because of the high mobility of it can be a contaminant to nature whether it is far away and long-term period from the source. in this research location, the quality of surface water and sludge include the concentration of cu and total cr are intense influenced by the weather. acknowledgement thanks to my lecture and all friends who always help and give a motivation to finish this research. references badan standardisasi nasional. 2005. sni 6989.57:2008. metoda pengambilan contoh air permukaan. jakarta. badan standardisasi nasional. 2004. sni 06-6989.17-2004. air dan air limbah-bagian 17 : cara uji krom total (cr-t) dengan metode spektrofotometri serapan atom (ssa)-nyala. jakarta. badan standardisasi nasional. 2004. sni 06-6989.15-2004. air dan air limbah-bagian 15 : cara uji tembaga (cu) dengan metode spektrofotometri serapan atom (ssa)-nyala. jakarta. badan pusat statistik. 2016. issn 2527-9009 nomor publikasi 16716.16.01 katalog 1102001.1671. kota palembang dalam angka 2016. cv. data network. palembang direktorat jenderal sumber daya air departemen pekerjaan umum.. 2009. keputusan direktur jenderal sumber daya air nomor 39/kpts/d/2009. pedoman konstruksi dan bangunan sipil survey dan monitoring sedimentasi waduk. jakarta. gubernur sumatera selatan. 2005. peraturan gubernur sumatera selatan no. 16 tahun 2005. peruntukan air dan baku mutu air sungai. palembang. gubernur sumatera selatan. 2012. peraturan gubernur sumatera selatan no. 8 tahun 2012. baku mutu limbah cair bagi kegiatan industri, hotel, rumah sakit, domestik dan pertambangan batubara. berita daerah provinsi sumatera selatan tahun 2012 nomor 8. palembang. menteri lingkugan hidup republik indonesia. 2014. keputusan menteri lingkungan hidup no. 5 tahun 2014. baku mutu air limbah. rusdiansyah, achmad. 2006. pola arus di kolam pasang surut akibat pengaruh angin. jurnal info teknik vol.7 no.1 juli 2006, 01-07. sujantoko. natakusumah, d.k.juli 2003.model simulasi interaksi gelombang dan arus di perairan dangkal. jurnal teknik sipil vol.10 no.03, 99-108. vodyanitskii, y. n. (2016). standards for the contents of heavy metals in soils. annals of agrarian science, 257-263. wulan, s. p., thamrin, & amin, b. (2013). konsentrasi, distribusi dan korelasi logam berat pb,cr dan zn pada air dan sedimen di perairan sungai siak sekitar dermaga pt. indah kiat pulp and paper perawang propinsi riau. kajian lingkungan, 72-92. table 2. decrease percentage of total cr sampling point critical points jun 2017 versus sep 2017 jul 2017 versus sep 2017 aug 2017 versus sep 2017 sludge surface water sludge surface water sludge surface water 1 a current 148,994 89,035 268,205 -2 b current 209,809 222,923 232,491 3 end of ab current 294,161 265,119 393,324 4 filling under craftsman 802,938 51,86% 840,107 49,39% 792,031 34,02% house and not flowing 5 swamp 76,860 38,38% 155,112 44,61% 96,765 32,81% title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 1, january 2023 research paper a multi-period model for optimal changi airport check-in counter operations nur haliza md alimuddin1, qatrunnada noor izzuddin2, muhammad amirul amat3, zati aqmar zaharudin4* 1citi transaction services (m) sdn bhd, menara citibank, kuala lumpur, 50450, malaysia2hiraki timur sdn bhd, kolej teknologi timur, sepang, 43900, malaysia3infosys, petaling jaya, selangor, 47410, malaysia4college of computing, informatics and media, universiti teknologi mara cawangan negeri sembilan, kampus seremban, 70300, malaysia *corresponding author: zati@uitm.edu.my abstractgrowth in air passenger flow has caused severe congestion at the airport check-in counter, posing a significant problem for airportmanagement. particularly during the check-in process, the necessary authorities must coordinate sufficient facilities with adequatestaffing levels. the airport check-in counter problem (accap) is a field concerned with establishing the optimal number of check-incounters to balance operating expenses and passenger wait times in order to reduce airport congestion. expanding the numberof counters and staff to a minimum operating cost is able to prevent the congestion problem from escalating without incurringfurther operating expenses. this paper focused on proposing optimal scheduling of airport check-in counters operations, includingstaffing. a dynamic model with multi-period principles is adapted to address the aforementioned problem by balancing the trade-offbetween service performance and operational cost. as a case study, data from singapore changi international airport was utilized.the findings are also discussed in terms of the flow of passengers throughout the airport check-in procedure and operations. as aresult, the number of activated counters is minimized throughout all shifts by applying the dynamic model at the average servicetime. at the same time, there are fewer passengers in the queue. keywordsairport check-in, scheduling, counter allocation, multi-period model received: 22 oktober 2022, accepted: 10 january 2023 https://doi.org/10.26554/sti.2023.8.1.116-122 1. introduction airport congestion and delays are caused by rapid air transport demand growth (zografos et al., 2017) . however, due to an unprecedented crisis due to the outbreak of the covid19 pandemic in 2020 (although some countries experience covid-19 in late 2019), almost all airports have been paralyzed (dabachine et al., 2020) . the number of passengers remained relatively consistent before covid-19 until plummeting dramatically due mainly to the pandemic from 2019 to 2020. nevertheless, the situation is showing a steady recovery path and the number of passengers is likely to increase. increased passenger numbers would initiate airport congestion problems (bruno et al., 2019; parlar and sharafali, 2008), especially in crucial areas such as check-in counters. the inability to accommodate passenger demand within capacity usage would incur delay costs to the airport terminal management (pita et al., 2013) . for this reason, it is important for airport management to sustain and maintain the availability of infrastructure (rajapaksha and jayasuriya, 2020) . however, increasing the airport capacity is not an option because that would require additional funding (xu et al., 2014) yet the airport terminal management must reduce congestion to guarantee that all passengers may board their flights on time. proper organization of the staff at these check-in counters directly influences passenger congestion and delay (xin et al., 2014) . in terms of the length of the queue and waiting periods, this setup achieves a balance between operational costs and the passenger’s level of acceptable service (bruno et al., 2019) . moreover, better service, shorter queues, and quicker check-ins for passengers will all result from more effective use of check-in counters (lalita and murthy, 2022) . in the case of restricted financing sources, increasing the number of counters and staff would incur more operating expenses; therefore, improving the current system at the minimum costs is the most effective way to handle this scenario. looking at this issue, this paper improves the airport’s operation of check-in counters at the singapore changi international airport, by applying a multi-period model specifically for solving the operational problem as proposed by bruno et al. (2019) . using this model, we can determine the appropriate https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.1.116-122&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.1.116-122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 number of active check-in counters for departing aircraft in order to reduce operating expenses. in addition, we noticed that the presence of mathematical modelling for addressing the problem for the airport check-in counter allocation (or in short, accap) was rather challenging, despite being one of the most crucial phases of air travel. consequently, utilizing a mathematical modelling approach to solve the corresponding issue is a significant advantage. the remainder of the paper is structured as follows: section 3 reviewed the relevant literature of the study area, section 4 describes the dynamic multi-period model and the data acquisition, and section 5 discussed the results. finally, the entire work of this paper is enclosed in section 6. 2. experimental section 2.1 past related studies the accap study focuses on allocating an adequate number of check-in counters so that the passenger waiting time is minimized and satisfactory service can be provided to the passengers over a given planning horizon with respect to certain constraints (nandhini et al., 2012) . the accap involves the optimization procedures in the decision making of service management. simulation approaches had gained attention from several studies. van dijk and van der sluis (2006) projected a combination of simulation and integer programming (ip) to solve the counters for check-in at brisbane airport corporation (bac) and dutch airport schiphol. the bac was also utilized by paloma garcia (2017) as case study, but using only on the simulation approach to analyze all the possibilities of different situations on bac such as variability in demand, services working, queuing type or redirection between areas. meanwhile, bevilacqua and ciarapica (2010) integrated queueing theory into the proposed simulation model. the simulation showed that optimization of average queuing times was preferred in a common check-in. a deterministic approach was adapted in solving accap, such as hsu et al. (2012) which utilized binary integer programming (bip) to minimize the total service time for the assignment of passengers. the authors indicated that a much wider network, such as the inclusion of check-in counters in the solution process, must be considered to ensure a faster passenger check-in process. meanwhile, al-sultan (2015) integrated ip and stochastic approach to propose the schedule for the check-in counter at the international airport in kuwait so that the total counters and staffing periods at these counters can be reduced. meanwhile, the stochastic approach was used to allocate the operational and staff scheduling at these counters. araujo and repolho (2015) applied three version of mixed integer linear programming (milp) formulation to a case study in amsterdam airport schiphol using the simulated and dynamic model. the milp formulations were applied to two check-in systems in accap which are the common accap (caccap) and the dedicated accap (daccap). both proposed deterministic models are able to find the total counters of check-in per time interval, but daccap is able to compute the solution for each flight. stochastic elements were also found in dynamic models’ approach in solving the accap such as study by parlar and sharafali (2008) . the proposed model was based on the multi-server queue by computing and generating the transient queueing probabilities. the study aimed to optimize the opening of the number of counters for passengers check-in over a specific period. meanwhile, dynamic opening and closing of counters approach was being used by nandhini et al. (2012) . the authors provide a satisfactory service level to passengers by reducing the average queuing time. similarly, marintseva (2014) focused on the problem of check-in technologies at the boryspil airport in ukraine. the authors adapted queuing theory of m/m/s model to find the optimal check-in counter operating periods. as a result, the waiting time at the check-in area could be minimized by almost one hour. focusing on parallel queuing, parlar et al. (2018) focused the problem of accap for a single flight. the authors found the optimal counters for check-in by deploying a real-event dynamic method. in 2018, parlar et al. (2018) analyzed the suitable number of counters for check-in at singapore changi international airport using the event-based dynamic programming model. meanwhile, bruno and genovese (2010) developed a dynamic mathematical model for both static and dynamic airport check-in problems by minimizing the expenses associated with the check-in service via optimal resource allocation. in 2014, bruno et al. (2014) developed supplementary variants of the dynamic model. the authors proposed a dynamic capacitated lot-sizing model and applied it to several practical logistic applications, including accap. in 2019, bruno et al. (2019) integrates staff scheduling within the proposed dynamic accap model. the authors applied the model in italy. our work focused on improving the facility operation, including providing an optimal number of staff at the counters for check-in. hence, the dynamic multi-period model proposed by bruno et al. (2019) is applied to solve the problem of the check-in counter operation at the selected case study, i.e., the singapore changi international airport. next section presents the dynamic multi-period model. 2.2 a multi-period model for airport check-in counters allocation problem let the planning horizon, t be divided into a finite number n indexed by t(t = 1, 2, ..., n). each t is assumed to be identical periods of length l. each departing flight f ( f = 1, 2, ..., f) in such time horizon is characterized a time window, in which check-in operations can be performed. assuming that checkin counter service times are consistent and passenger arrivals increase over time, a queue will undoubtedly form. hence, these passengers in the queue, with notation if t, is assumed will be served during the subsequent period. thus, the dynamic multi-period model proposed by bruno et al. (2019) is consuming this scenario as the conservation flow of passengers. © 2023 the authors. page 117 of 122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 the remaining indices, sets, parameters, and decision variables of the model are as follows: t planning horizon; n number of periods in which the planning horizon is subdivided, indexed by t; l length of single period; j set of shift types that can be selected for check-in counters operators; f index of departing flights in the considered planning horizon; qf average service time to process a single passenger of flight f at check-in counters; df t arrival of passengers of flight f during period t; 𝛾 service level to be guaranteed i.e., minimum number of passengers to be accepted expressed as percentage of arrivals; cj cost for shift type j in j; a j kt binary parameter equal to 1 if and only if the shift j in j, activated in the period k covers the period t (with t > k); 𝛽 f t binary parameter equal to 1 if and only if the check-in time window for flight f is closed in period t; x jt number or operators starting the shift type j at the beginning of period t; qf t passengers of flight f accepted at the check-in counters in period t; if t passengers of flight f in queue at the check-in counters at the end of period t; the dynamic multi-period model as follows: min z = j∑︁ j=1 n∑︁ t=1 cjx j t (1) where 𝛽 f tif t = 0;∀f = 1, 2, ..., f , ∀t = 1, 2, ..., n (2) if t = if (t−1) +df t −qf t;∀f = 1, 2, ..., f , ∀t = 1, 2, ..., n (3) ∑︁ f ∈f if t ≤ (1 − 𝛾) ∑︁ f ∈f df t;∀t = 1, 2, ..., n (4) ∑︁ f ∈f pf qf t ≤ l ∑︁ f ∈f ∑︁ k=1 a j kt x jt ;∀f = 1, 2, ..., f , ∀t = 1, 2, ..., n (5) x jt ≥ 0;∀j ∈ j , ∀t = 1, 2, ..., n (6) qf t, if t ∈ {0, 1};∀f = 1, 2, ..., f , ∀t = 1, 2, ..., n (7) the objective function of the model as shown in (1) aims to minimize the total cost for the activated counters at all times and across all shifts. equations (2)-(5) present the constraints of the model. constraint (2) dictates that passengers of each flight f will only be attended to during their designated check-in time windows. additionally, this constraint guarantees that no queue forms outside of the flight f check-in time windows. constraint (3) sets passenger flow conservation limits, i.e., within the check-in time windows, passengers are served or else wait in a queue. therefore, guarantees that all passengers are served within the operational times of the check-in counter. inequalities (4) restrict the queue to a specified percentage based on the arrival of passengers. inequalities (5) represent the level of service capacity. finally, constraints (6) and (7) characterize the decision variables of the model. 2.3 data acquisitions singapore changi international airport has become a global leader in the airport industry in less than 30 years, according to the prestigious publication business traveler (bok, 2015) and has become a global leader in the airport business (lee et al., 2014) . the airport has been the skytrax airport of the year winners since 2013 (wu and tsui, 2020) . prior to covid-19, changi airport handled around 68.3 million passengers in 2019, representing a 4.0% growth over the previous year, via 100 airlines serving 400 cities in approximately 100 countries and territories worldwide (lee et al., 2022) . airport passenger traffic has increased significantly since the pandemic ended, and this trend is expected to continue. table 1 provides information from parlar et al. (2018) regarding airport check-in counters, including the total number of counters used, the number of available counters for each 5minutes duration, and the number of passengers (m). as seen, m has an average of 149 passengers for every flight, ranging from 81 to 261 passengers. with a range of 1 hour 8 to 2 hours 45 minutes, the average operation time for the check-in counter is 1 hour 34 minutes. it is observed that the minimum counter needed for the check-in process is one, while the maximum is four. the total number of counters used reflects the assumption that each counter has the same amount of staff allocation. the operation of these counters for every five minutes, as shown in the final column of table 1. in general, as time increases, the number of operational counters in 5 minutes period decreases. although these numbers are consistent with the operation of check-in counters but are highly dependent on the quantity of passengers arriving at each time interval. parlar et al. (2018) discovered that around six passengers arrived at the check-in counter, with the average waiting time for each flight ranging from 57 seconds to 16 minutes and 28 seconds. instead of the number of passengers in each queue, parlar et al. (2018) assigned enumerators to each activated counter for observing the system operation. therefore, the pattern used to © 2023 the authors. page 118 of 122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 table 1. details of the operation of counters of 14 randomly selected flights (source: parlar et al. (2018) ) flight, f m check-in counter operational times duration (hour:min) number of counters used f01 81 03:59-05:28 01:29 1 f02 156 04:00-05:20 01:20 3 f03 121 03:48-05:58 02:10 2 f04 131 05:06-06:28 01:22 2 f05 111 08:35-10:00 01:25 4 f06 137 10:35-11:50 01:15 3 f07 145 10:57-12:22 01:25 2 f08 185 12:55-15:15 02:20 2 f09 151 14:55-16:03 01:08 4 f10 167 15:50-17:15 01:25 3 f11 131 16:45-18:05 01:20 2 f12 138 18:45-20:05 01:20 3 f13 261 18:58-20:32 01:34 4 f14 172 21:25-00:10 02:45 2 table 2. total activated check-in counters for each shift ( ∑t t x j t ) , for three scenarios scenario total number of check-in counters for all t for each shift j ( ∑t t x j t ) morning afternoon night actual 26 40 26 pf = 1.5 24 40 25 pf = 4.0 32 42 29 distribute the total number of passengers for each time period follows the international air transport association’s (iata) distribution, as obtained from ahyudanari (2003) . to suit the model of bruno et al. (2019) , information of table 1 was modified according to 10-minute time interval (as presented in figure 1). the time periods were classified into three shifts, namely morning, afternoon, and night shifts. figure 1 illustrates the arrival of passengers regarding the shift and the flight. flights f01 through f05 are covered during the morning shift, which is between 00:10 and 9:50. check-in activities for the afternoon shift occur between 10:00 and 18:00, covering flights f06 to f11. finally, the night shift is from 18:10 to 00:00 and includes flights f12 to f14. meanwhile, the number of activated counters for check-in of each shift is depicted in figure 2. the morning shift has a maximum of two activated counters, the afternoon shift has one activated counter, and the night shift has a maximum of two activated counters. please note that each activated counter is expected to have one working staff. meanwhile, for this study, it is assumed that the cost of staffing the counter is constant throughout shift j. the 𝛽 f t is based on the estimated departure time for each flight f . it is assumed that the check-in counter would be open for three hours. subsequently, the departure time was set 30 minutes after the counter closing time. for instance, the departure time for flight f01 is 6.30 a.m., hence it is assumed figure 1. passengers’ arrival distributions based on iata arrival distribution (source: ahyudanari (2003) ) that the check-in counter will be open three hours prior, at 3.30 a.m., and close 30 minutes prior, at 6.00 a.m. it is presumed that all passengers could check in before the flight’s departure. the value of pf parameter was set to 1.5 and 4.0 minutes. the average service time is 1.5 minutes, while the maximum service duration is 4 minutes. the service level, 𝛾, denotes the guaranteed service level as the expenses of check-in processes that must be minimized by taking queue length into account, i.e., the number of passengers who are still in line. the value of 𝛾 is set consistently at 0.2 or 20% of service level is guaranteed to passengers, it is regarded that less than 80% of passengers are still in queue at the check-in counters at the end of time t. the problem is solved by cplex solver using a pc with © 2023 the authors. page 119 of 122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 figure 2. actual operating counters for each shift within a 10-minutes interval configuration: intel core i5 cpu 3.1 ghz, ram 12.00 gb, and 64-bit windows 10 operating system 3. result and discussion the check-in counter operators were assigned based on the optimal number of counters to be opened in each shift. some of these counters may be unused due to the unpredictable arrival pattern every flight. during off-peak hours, the number of unused counter(s) or operational capacity can be minimized. this can be identified by modifying the number of counters based on value 𝛾=0.2 and pf at 1.5 and 4.0. the optimal number of activated counters is shown in table 2 for three scenarios, which are, the actual, pf =1.5 and pf =4.0. from table 2, for the morning shift, for actual scenario, from 12:01 a.m. and 10:00 a.m. there are 26 check-in counters are activated (with a 10-minute interval) for all five flights f01, f02, f03, f04, and f05. when pf =1.5, the optimal number of activated counters is reduced to 24, and when pf =4.0, this number increased to 32. this indicates that additional counters must be activated to serve airline passengers when the service time increases. figure 3 illustrates the activated counters for each shift for better understanding. figure 3. total number of check-in counter for each shift within a 10-minute interval, under three different shifts figure 4 depicts the total number of passengers served by the activated counters by shift, using pf values of 1.5 and 4.0. figures 4(a) and 4(b) show that for both pf values, some passengers served for each 10-minute time interval for each flight are slightly different. figure 5 is derived from both figures 4(a) and 4(b) that highlight the number of passengers served by flight f13. for each value of pf , the highest number of passengers served by the activated counter occurs at a different time. when pf is 1.5, 78 passengers are served at 19:40, however when pf is 4.0 only 60 passengers are served at 19:30. when the maximum service time, pf is used, fewer passengers will be served. it could be noted that the average service time required to process a single flight passenger at the check-in counter has a substantial impact on the total number of passengers in queue. in addition, for our study, because a single check-in counter is activated for each flight during the night shift, it is anticipated that this situation may occur. this is investigated further utilizing the decision variable of the number of passengers in the queue (if t). figure 4. total number of passengers served for each shift within a 10-minute interval, using two service times figure 5. total number of passengers served for f13 within a 10-minute interval, using two service times table 3 depicts the number of passengers in queue for pf values of 1.5 and 4.0 while keeping a service level, 𝛾 at 0.2. the actual number of passengers for each shift is shown in the same table. it is found that for pf = 1.5 and 4.0, the highest © 2023 the authors. page 120 of 122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 table 3. number of passengers in the queue at check-in counters ( ∑t t ∑f f if t ) shift actual number of passengers (m) passengers of all flight f in queue at check-in counters at the end of period t ( ∑t t ∑f f if t ) pf =1.5 pf =4.0 morning 600 227 (38%) 254 (42%) afternoon 916 132 (14%) 220 (24%) night 571 247 (43%) 221 (39%) table 4. comparison between the actual and predicted on the total activated counters at all time t and for all flight f for each shift j ( ∑t t x j t ) shift actual pf = 1.5 difference (%)* actual pf = 4.0 difference (%)* morning 26 24 -7.70% 26 32 23.10% afternoon 40 40 40 42 5% night 26 25 -3.80% 26 29 10.30% *note:difference (%) = (predicted – actual)/actual × 100% number of passengers in the queue during the night shift was 247 (43%) and 221 (39%), respectively. the afternoon shift has the most passengers despite being the shortest queue, i.e., pf = 1.5 is 132 (14%) and pf = 4.0 is 220 (24%). as indicated earlier, the night shift is most likely to have the longest queue length because each flight has just one activated counter. from table 2, we can see that the total counters that were activated for all times t and flight f during the night shift for both pf values are the least ones. meanwhile, the afternoon shift has the highest number of total activated counters; hence, this shift is expected to have the shortest queues. table 4 provided a summary of the findings based on the actual, projected, and difference percentage values. for service times of 1.5 minutes, the model underestimates the total number of activated counters during the morning and night shifts. for maximum service times, i.e., 4.0 minutes, the model overestimated the total number of activated counters throughout all shifts. the average absolute percentage difference between actual and predicted outputs is 8.4%. from the findings, the model’s suitability for system operation monitoring, particularly for the cause-and-effect analysis, has been demonstrated. clearly, less counters for check-in were activated at time t due to a shorter average service time to process a passenger. thus, more passengers can be accepted at time t in the designated capacity level. the model can estimate the optimal check-in counters based on system capacity and service availability. this study utilizes two service times, namely, the average service times and the maximum service times that guarantee a service level of 80%. when the service time is relatively short, only 24 counters should be activated during morning shift, 40 counters during afternoon shift, and 25 counters during night shift. meanwhile, extended service times requires more counters, specifically 32 counters for the morning shift, 42 counters for the afternoon shift, and 29 counters for the night shift. consequently, the utilized multi-period model was able to identify the appropriate number of total activation counters for changi airport, precisely for the corresponding airlines. our study shows that there is a direct correlation between the optimal number of active check-in counters, the total number of passengers served during each 10-minute interval, and the total number of passengers waiting in the queue are existing. 4. conclusion this study focuses on optimizing the facility’s operations, including supplying the optimal number of check-in counters, so that overall demand can be served at a maximum level at the minimum cost. this paper utilized the dynamic multiperiod model developed by bruno et al. (2019) to solve the check-in counter operation problem at the selected case study, i.e., changi international airport in singapore. the applied model demonstrates that the number of passengers in the queue increases in relation to service level guarantees. the results obtained clearly minimize the total cost for the activated check-in counters at all times and throughout all shifts, especially when the average service time is 1.5 minutes. clearly, there is a direct correlation between the optimal number of active check-in counters and the total number of passengers served during each 10-minute interval, as well as the total number of passengers waiting in the queue. utilizing the dynamic model, the airline check-in flow at the counters can be optimized. furthermore, the results show any adjustments would have direct effects on airport operations. if a more comprehensive dataset is used, airport operations will undoubtedly become more productive and economical. additionally, this study shows a decision© 2023 the authors. page 121 of 122 alimuddin et. al. science and technology indonesia, 8 (2023) 116-122 making model that employs the dynamic characteristics of a multi-period model can provide insights on management’s decision-making solutions. further enhancements to the mathematical model presented in this paper could be constructed to replicate the real-world scenario, such as integrating specific measurements for counter activation for each time period and flight or imposing a limit on the total number of employees working at activated counters. 5. acknowledgment the authors are appreciative of the insightful suggestions made by the anonymous reviewers, which significantly improved the paper. references ahyudanari, e. 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a case study of singapore changi airport. journal of air transport management, 82; 101742 xin, z., d. lin, y. huang, w. cheng, and c. c. teo (2014). design of service capacity for the ground crew at the airport check-in counters. international journal of quality and service sciences, 6(1); 43–59 xu, s. z., r. m. wang, b. zhu, j. f. zhu, and j. du (2014). operation optimization of the airport check-in system. applied mechanics and materials, 457; 1665–1668 zografos, k. g., m. a. madas, and k. n. androutsopoulos (2017). increasing airport capacity utilisation through optimum slot scheduling: review of current developments and identification of future needs. journal of scheduling, 20(1); 3–24 © 2023 the authors. page 122 of 122 introduction experimental section past related studies a multi-period model for airport check-in counters allocation problem data acquisitions result and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper the subclasses of analytic functions of complex order with application of q-derivative operators aini janteng1*, desmond lee ching yiing2, yong enn lun1*, jaludin janteng3, lee see keong4, rashidah omar5, andy liew pik hern1 1faculty of science and natural resources, universiti malaysia sabah, kota kinabalu, sabah, 88400, malaysia2faculty of science, universiti teknologi malaysia, johor bahru, johor, 81310, malaysia3labuan faculty of international finance, universiti malaysia sabah, federal territory of labuan, 87000, malaysia4school of mathematical sciences, universiti sains malaysia, penang, 11800, malaysia5faculty of computer and mathematical sciences, universiti teknologi mara cawangan sabah, kota kinabalu, sabah, 88997, malaysia *corresponding author: aini−jg@ums.edu.my; yongel@ums.edu.my abstractin this article, we represent a as the of analytic functions in the open unit disk. further, new subclasses of analytic functions ofcomplex order utilising q-derivative operator are generated. the subclasses are symbolised by hq,b(𝜑) and iq,b(𝜑). additionally, wediscover that these function classes are implicated with the fekete-szegö inequalities. keywordsanalytic, q-derivative operator, fekete-szegö inequality received: 24 march 2023, accepted: 10 june 2023 https://doi.org/10.26554/sti.2023.8.3.436-442 1. introduction in recent times, research on the field of quantum calculus is actively being done by mathematicians. this is demonstrated by the use of it in the study of complex analysis, particularly geometry functions theories. quantum calculus referred to as calculus without limits, is a kind of standard infinitesimal calculus that does not include the concept of limits. the terms q-calculus and h-calculus are defined, where q is quantum and h is planck’s constant. q-calculus bridges the gap between physics and mathematics. its applications are often seen in numerous branches of mathematics such as discrete mathematics, complex numbers, fundamental hypergeometric polynomials, symmetric coefficients, as well as other fields like quantum physics, general relativity and mechanics. jackson (1908) and jackson (1910) started the implementation of q-calculus. jackson pioneered the q-integral and q-derivative systematically. motivated by the research by aldweby and darus (2016) and aldweby and darus (2017) , this study focuses on the q-derivative in defining several subclasses of analytic functions. in the current study, let a symbolise the class of analytic functions in the open unit disk 𝕆 = {z : z ∈ ℂ, |z | < 1}. the analytic function is represented by function f and has a maclaurin series expansion as below: f (z) = z + ∞∑︁ 𝜏=2 a𝜏 z 𝜏 , a𝜏 ∈ ℂ, z ∈ 𝕆 (1) by jeyaraman and suresh (2014) , if f and g are represented by the analytic functions in 𝕆, then the subordinate to g is f denoted as f ≺ g in 𝕆 or f (z) ≺ g(z) for all z ∈ 𝕆 if the presence of the schwarz function w(z) is analytic in 𝕆 that has the properties |w(z)| < 1 and w(0) = 0 for all z ∈ 𝕆 such that f (z) = g(w(z)), z ∈ 𝕆 in the case g is univalent, we can state that f ≺ g, if and only if f (0) = g(0) and f (𝕆) ⊆ g(𝕆). now, we provide the basic definition of q-derivative in this study. let dq f symbolise the q-derivative operator of f with 0 < q < 1. it is defined in aral et al. (2013); jackson (1908) as below: dq f (z) = { f (qz )− f (z ) (q−1)z , z ≠ 0 and q ≠ 1 f ′(0), z = 0 (2) in view of (1) and (2), it can be shown that https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.436-442&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.436-442 janteng et. al. science and technology indonesia, 8 (2023) 436-442 dq( f (z)) = 1 + ∞∑︁ 𝜏=2 [𝜏]qa𝜏 z 𝜏−1 where the formulae of [𝜏]q is given as below: [𝜏]q = 1 − q𝜏 1 − q and noted that as q → 1−, [𝜏]q → 𝜏. in the studies of previous researchers, several new subclasses of analytic functions utilising q-derivative operator have been proposed. aldweby and darus (2016) have introduced the following subclasses: s∗q (𝛾) = { f ∈ a : re ( zdq( f (z)) f (z) ) > 𝛾, z ∈ 𝕆 } and cq(𝛾) = { f ∈ a : re ( 1 + zqdq(dq( f (z)) dq( f (z)) ) > 𝛾, z ∈ 𝕆 } where 0 ≤ 𝛾 < 1. further, if q → 1−, the class s∗q (𝛾) and cq(𝛾) reduces to the starlike functions of order 𝛾, s∗(𝛾), and convex functions of order 𝛾, c(𝛾), respectively. furthermore, there are several new subclasses of a involving q-derivative that have been introduced by other mathematicians (see aldweby and darus, 2017; alsoboh and darus, 2019; altinkaya and yalçin, 2017; bulut, 2017; janteng and halim, 2009b; karahuseyin, 2017; lashin et al., 2021; hern et al., 2022; hern et al., 2020; olatunji and dutta, 2018; piejko and sokół, 2020; ramachandran et al., 2017; shamsan et al., 2021; shilpa, 2022). in fact seoudy and aouf (2016) have introduced how classes of q-convex and q-starlike of complex order can be obtained using the principle of subordination and q-derivative. this study has inspired other mathematicians to study subclasses of analytic functions of complex order utilising q-derivative (see ali and el ashwah, 2021; ibrahim et al., 2020; purohit and raina, 2014; selvaraj et al., 2017; srivastava and el deeb, 2020; srivastava and zayed, 2019). the research from seoudy and aouf (2016) and the research from janteng and halim (2009a) ; janteng and halim (2020) serves as our inspiration as we utilise the q-derivative of f ∈ a and the subordination principle to propose new subclasses of analytic functions of complex order. definition 1. let p represents the class of analytic and univalent functions 𝜑(z) in 𝕆. 𝜑(z) is convex with the properties 𝜑(0) = 1 and re(𝜑(z)) > 0 for all z ∈ 𝕆. f ∈ a is considered as belonging to class hq,b(𝜑) if f fulfils the subordination criteria as below: 1+ 1 b [ zdq( f (z)) f (z) + 𝜖qz2dq ( dq( f (z)) ) f (z) − 1 ] ≺ 𝜑(z) (3) with 𝜖 ≥ 0, b ∈ ℂ\{0} , and 𝜑(z) ∈ p. definition 2. f ∈ a is considered as belonging to class iq,b(𝜑) if f fulfils the subordination criteria as below: 1+ 1 b [( zdq( f (z)) f (z) )𝜖 ( 1 + zqdq(dq( f (z))) dq( f (z)) )1−𝜖 − 1 ] ≺ 𝜑(z) with 𝜖 ≥ 0, b ∈ ℂ \ {0} ,and 𝜑(z) ∈ p. the demonstration of our key findings requires the use of the preceding lemmas. lemma 1. ma and minda (1992) if 𝜐 is a complex number and p(z) = 1 + c1z + c2z2 + · · · is a function that has a positive real part in 𝕆, then |c2 − 𝜐c21 | ≤ 2max {1, |2𝜐 − 1|} (4) the equality (4) holds for functions provided by p(z) = 1 + z 1 − z and p(z) = 1 + z2 1 − z2 lemma 2. ma and minda (1992) if p(z) = 1 + c1z + c2z2 + · · · is a function that has a positive real part in 𝕆, then |c2 − 𝜐c21 | ≤  −4𝜐 + 2 if 𝜐 ≤ 0 2 if 0 ≤ 𝜐 ≤ 1 4𝜐 − 2 if 𝜐 ≥ 1 when 𝜐 < 0 or 𝜐 > 1, the result is sharp if and only if p(z) = 1 + z 1 − z or a rotation of itself. if 0 < 𝜐 < 1, the result is sharp if and only if p(z) = 1 + z2 1 − z2 or a rotation of itself. if 𝜐 = 0, the result is sharp if and only if p(z) = ( 1 2 + 1 2 𝛿 ) · 1 + z 1 − z + ( 1 2 − 1 2 𝛿 ) · 1 − z 1 + z (0 ≤ 𝛿 ≤ 1) © 2023 the authors. page 437 of 442 janteng et. al. science and technology indonesia, 8 (2023) 436-442 or a rotation of itself. if 𝜐 = 1, the result is sharp if and only if p(z) is the reciprocal of a function of itself such that the result is sharp when 𝜐 = 0. it is a sharp upper bound, with the possible improvements when 0 < 𝜐 < 1: |c2 − 𝜐c21 | + 𝜐 |c1| 2 ≤ 2 (0 ≤ 𝜐 ≤ 1/2) and |c2 − 𝜐c21 | + (1 − 𝜐)|c1| 2 ≤ 2 (1/2 ≤ 𝜐 ≤ 1) 2. results and discussion throughout this study, the fekete-szegö inequalities for classes hq,b(𝜑) and iq,b(𝜑) provided 0 < q < 1, b ∈ ℂ \ {0} and 𝜑(z) ∈ p and z ∈ 𝕆 are obtained. theorem 1. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 ≠ 0. if f is provided by equation (1) in class hq,b(𝜑) with y ≥ 0, then |a3 − `a22 | ≤ |b1b| q[2]q(y[3]q + 1) max { 1; ����b2b1 + b1bq(y[2]q + 1) ( 1 − [2]q(y[3]q + 1) y[2]q + 1 ` )����} proof. let f ∈ hq,b(𝜑), then f fulfils subordination (3). according to the subordination principle, the schwarz function w(z) is present, and it is analytic in 𝕆, which has the properties w(0) = 0 and |w(z)| < 1 such that 1+ 1 b [ zdq( f (z)) f (z) + yqz2dq(dq( f (z))) f (z) − 1 ] = 𝜑(w(z)) (5) let p(z) be a function which is defined by p(z) = 1 + w(z) 1 − w(z) = 1 + c1z + c2z2 + · · · (6) since w(z) is a schwarz function, it is obvious for re(p(z)) > 0 and p(0) = 1. in view of equation (6), we obtain w(z) = p(z) − 1 p(z) + 1 = 1 2 [ c1z + ( c2 − c21 2 ) z 2 + . . . ] (7) from equation (5) and (7), we obtain 𝜑(w(z)) = 1+ 1 2 b1c1z + [ 1 2 b1 ( c2 − c21 2 ) + 1 4 b2c 2 1 ] z 2+. . . (8) now, by utilising equation (1) and (2), we obtain 1 + 1 b [ zdq( f (z)) f (z) + 𝜖qz2dq(dq( f (z))) f (z) − 1 ] = 1 + q(y[2]q + 1)a2z b + q ( [2]q(y[3]q + 1)a3 − (y[2]q + 1)a22 ) z2 b + . . . (9) by utilising equation (8) and (9), we compare the coefficients of z and z2, q(y[2]q + 1)a2 b = 1 2 b1c1 q([2]q(y[3]q + 1)a3 − (y[2]q + 1)a22) b = 1 2 b1 ( c2 − c21 2 ) + 1 4 b2c 2 1 or equivalently, a2 = b1c1b 2q(𝜖 [2]q + 1) (10) a3 = b1c2b 2q[2]q(y[3]q + 1) − b1c21b 4q[2]q(y[3]q + 1) + b2c21b 4q[2]q(𝜖 [3]q + 1) + b21c 2 1b 2 4q2[2]q(𝜖 [2]q + 1)(𝜖 [3]q + 1) (11) next, by utilising equation (10) and (11), we obtain a3 − `a22 = b1b 2q[2]q(y[3]q + 1)[ c2 − 1 2 [ 1 − b2 b1 − b1b q(𝜖 [2]q + 1) ( 1 − [2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 ` )] c21 ] (12) if we take © 2023 the authors. page 438 of 442 janteng et. al. science and technology indonesia, 8 (2023) 436-442 𝜐 = 1 2 [ 1 − b2 b1 − b1b q(𝜖 [2]q + 1) ( 1 − [2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 ` )] then, from equation (12), |a3 − `a22 | = |b1b| 2q[2]q(𝜖 [3]q + 1) ���c2 − 𝜐c21��� (13) as we demonstrate, the fekete-szegö inequality is derived for the class hq,b(𝜑) by applying inequality (4) of lemma 1 in equation (13). theorem 1 has been successfully proved. by setting b = 1, theorem 1 has a corollary as below. corollary 1. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 ≠ 0. if f provided by equation (1) is in class hq(𝜑) with y ≥ 0, then |a3 − `a22 | ⩽ |b1| q[2]q(y[3]q + 1) max { 1, ����b2b1 + b1q(y[2]q + 1) ( 1 − [2]q(y[3]q + 1) y[2]q + 1 ` )����} theorem 2. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 > 0 and b2 ≥ 0. let 𝜎1 = (y[2]q + 1)b21b + q(y[2]q + 1) 2(b2 − b1) [2]q(y[3]q + 1)b21b 𝜎2 = (𝜖 [2]q + 1)b21b + q(𝜖 [2]q + 1) 2(b2 + b1) [2]q(𝜖 [3]q + 1)b21b and 𝜎3 = (𝜖 [2]q + 1)b21b + q(𝜖 [2]q + 1) 2b2 [2]q(𝜖 [3]q + 1)b21b if f is provided by equation (1) in class hq,b(𝜑) with 𝜖 ≥ 0 and b > 0, then |a3 − `a22 | ≤  b2b q[2]q (𝜖 [3]q+1) + b21b 2 q2[2]q (𝜖 [2]q+1) (𝜖 [3]q+1)( 1 − [2]q(𝜖 [3]q+1) 𝜖 [2]q+1 ` ) , ` ≤ 𝜎1 b1b q[2]q (𝜖 [3]q+1) , 𝜎1 ≤ ` ≤ 𝜎2 − b2bq[2]q (𝜖 [3]q+1) − b21b 2 q2[2]q (𝜖 [2]q+1) (𝜖 [3]q+1)( 1 − [2]q(𝜖 [3]q+1) 𝜖 [2]q+1 ` ) , ` ≥ 𝜎2 further, if 𝜎1 ≤ ` ≤ 𝜎3, then |a3 − `a22 | + q(𝜖 [2]q + 1)2 [2]q(𝜖 [3]q + 1)b21b[ b1 − b2 − b21b q(𝜖 [2]q + 1) ( 1 − `[2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 )] |a2|2 ≤ b1b q[2]q(𝜖 [3]q + 1) and if 𝜎3 ≤ ` ≤ 𝜎2, then |a3 − `a22 | + q(𝜖 [2]q + 1)2 [2]q(𝜖 [3]q + 1)b21b[ b1 + b2 + b21b q(𝜖 [2]q + 1) ( 1 − `[2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 )] |a2|2 ≤ b1b q[2]q(𝜖 [3]q + 1) proof. by utilising lemma 2 in equation (12), we can obtain the results in theorem 2. by setting b = 1, theorem 2 has a corollary as below. corollary 2. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 > 0 and b2 ≥ 0. let 𝜎1 = (y[2]q + 1)b21 + q(y[2]q + 1) 2(b2 − b1) [2]q(y[3]q + 1)b21 𝜎2 = (𝜖 [2]q + 1)b21 + q(𝜖 [2]q + 1) 2(b2 + b1) [2]q(𝜖 [3]q + 1)b21 and 𝜎3 = (𝜖 [2]q + 1)b21 + q(𝜖 [2]q + 1) 2b2 [2]q(𝜖 [3]q + 1)b21 if f provided by equation (1) is in class hq(𝜑) with 𝜖 ≥ 0, then |a3 − `a22 | ≤  b2 q[2]q (𝜖 [3]q+1) + b21 q2[2]q (𝜖 [2]q+1) (𝜖 [3]q+1)( 1 − [2]q(𝜖 [3]q+1) 𝜖 [2]q+1 ` ) , ` ≤ 𝜎1 b1 q[2]q (𝜖 [3]q+1) , 𝜎1 ≤ ` ≤ 𝜎2 − b2q[2]q (𝜖 [3]q+1) − b21 q2[2]q (𝜖 [2]q+1) (𝜖 [3]q+1)( 1 − [2]q(𝜖 [3]q+1) 𝜖 [2]q+1 ` ) , ` ≥ 𝜎2 © 2023 the authors. page 439 of 442 janteng et. al. science and technology indonesia, 8 (2023) 436-442 further, if 𝜎1 ≤ ` ≤ 𝜎3, then |a3 − `a22 | + q(𝜖 [2]q + 1)2 [2]q(𝜖 [3]q + 1)b21[ b1 − b2 − b21 q(𝜖 [2]q + 1) ( 1 − `[2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 )] |a2|2 ≤ b1 q[2]q(𝜖 [3]q + 1) and if 𝜎3 ≤ ` ≤ 𝜎2, then |a3 − `a22 | + q(𝜖 [2]q + 1)2 [2]q(𝜖 [3]q + 1)b21[ b1 + b2 + b21 q(𝜖 [2]q + 1) ( 1 − `[2]q(𝜖 [3]q + 1) 𝜖 [2]q + 1 )] |a2|2 ≤ b1 q[2]q(𝜖 [3]q + 1) in addition, as shown above, the fekete-szegö inequality is discovered for the class iq,b(𝜑). we get the required outcome by carrying out the processes as in theorem 1. theorem 3. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 ≠ 0. if f is provided by equation (1) in class iq,b(𝜑) with 𝜖 ≥ 0, then |a3 − `a22 | ≤ |b1b| q𝛿3[2]q max { 1, �����b2b1 + b1bq𝛿23 ( 𝜌 + `𝛿3[2]q) ����� } where 𝜌 = 𝜖 − 𝜖 (𝜖 − 1) 2 q([2]2q + 1) + (1 − 𝜖)[2]q(𝜖q − [2]q) and 𝛿𝜏 = 𝜖 + (1 − 𝜖)[𝜏]q. by setting b = 1, theorem 3 has a corollary as below. corollary 3. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 ≠ 0. if f is provided by equation (1) in class iq(𝜑) with 𝜖 ≥ 0, then |a3 − `a22 | ≤ |b1| q𝛿3[2]q max { 1, �����b2b1 + b1q𝛿23 ( 𝜌 + `𝛿3[2]q) ����� } where 𝜌 = 𝜖 − 𝜖 (𝜖 − 1) 2 q([2]2q + 1) + (1 − 𝜖)[2]q(𝜖q − [2]q) and 𝛿𝜏 = 𝜖 + (1 − 𝜖)[𝜏]q. theorem 4. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 > 0 and b2 ≥ 0. let 𝜎4 = 𝜌b21b + q𝛿 2 2(b2 − b1) 𝛿3[2]qb21b , 𝜎5 = 𝜌b21b + q𝛿 2 2(b2 + b1) 𝛿3[2]qb21b , and 𝜎6 = 𝜌b21b + q𝛿 2 2b2 𝛿3[2]qb21b . if f is provided by equation (1) in class iq,b(𝜑) with 𝜖 ≥ 0 and b > 0, then |a3− `a22 |  b2b 𝛿3q[2]q + b 2 1b q2𝛿22𝛿3[2]q ( 𝜌 − `𝛿3[2]q), ` ≤ 𝜎4 b1b 𝛿3q[2]q , 𝜎4 ≤ ` ≤ 𝜎5 − b2b 𝛿3q[2]q − b 2 1b q2𝛿22𝛿3[2]q ( 𝜌 − `𝛿3[2]q), ` ≥ 𝜎5 further, if 𝜎4 ≤ ` ≤ 𝜎6, then |a3 − `a22 | + q𝛿22 𝛿3[2]qb21b [ b1 − b2 − b21b q𝛿22 ( 𝜌 − `𝛿3[2]q) ] |a2|2 ≤ b1b 𝛿3q[2]q and if 𝜎6 ≤ ` ≤ 𝜎5, then |a3 − `a22 | + q𝛿22 𝛿3[2]qb21b [ b1 + b2 + b21b q𝛿22 ( 𝜌 − `𝛿3[2]q) ] |a2|2 ≤ b1b 𝛿3q[2]q where 𝜌 = 𝜖 − 𝜖 (𝜖 − 1) 2 q([2]2q + 1) + (1 − 𝜖)[2]q(𝜖q − [2]q) © 2023 the authors. page 440 of 442 janteng et. al. science and technology indonesia, 8 (2023) 436-442 and 𝛿𝜏 = 𝜖 + (1 − 𝜖)[𝜏]q. by setting b = 1, theorem 4 has a corollary as below. corollary 4. let 𝜑(z) = 1 + b1z + b2z2 + · · · with b1 > 0 and b2 ≥ 0. let 𝜎4 = 𝜌b21 + q𝛿 2 2(b2 − b1) 𝛿3[2]qb21 , 𝜎5 = 𝜌b21 + q𝛿 2 2(b2 + b1) 𝛿3[2]qb21 and 𝜎6 = 𝜌b21 + q𝛿 2 2b2 𝛿3[2]qb21 if f is provided by equation (1) in class iq(𝜑) with 𝜖 ≥ 0 then |a3−`a22 | ≤  b2 𝛿3q[2]q + b 2 1 q2𝛿22𝛿3[2]q ( 𝜌 − `𝛿3[2]q), ` ≤ 𝜎4 b1 𝛿3q[2]q , 𝜎4 ≤ ` ≤ 𝜎5 − b2 𝛿3q[2]q − b 2 1 q2𝛿22𝛿3[2]q ( 𝜌 − `𝛿3[2]q), ` ≥ 𝜎5 further, if 𝜎4 ≤ ` ≤ 𝜎6, then |a3 − `a22 | + q𝛿22 𝛿3[2]qb21 [ b1 − b2 − b21 q𝛿22 ( 𝜌 − `𝛿3[2]q) ] |a2|2 ≤ b1 𝛿3q[2]q and if 𝜎6 ≤ ` ≤ 𝜎5, then |a3 − `a22 | + q𝛿22 𝛿3[2]qb21 [ b1 + b2 + b21 q𝛿22 ( 𝜌 − `𝛿3[2]q) ] |a2|2 ≤ b1 𝛿3q[2]q where 𝜌 = 𝜖 − 𝜖 (𝜖 − 1) 2 q([2]2q + 1) + (1 − 𝜖)[2]q(𝜖q − [2]q) and 𝛿𝜏 = 𝜖 + (1 − 𝜖)[𝜏]q. 3. conclusion this study demonstrates two 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(2022). fekete-szegö inequalities for certain analytic functionsassociated with q derivative operator. advances and applications in mathematical sciences, 21(4); 2125– 2135 srivastava, h. m. and s. m. el deeb (2020). a certain class of analytic functions of complex order connected with a q-analogue of integral operators. miskolc mathematicalnotes, 21(1); 417–433 srivastava, r. and h. m. zayed (2019). subclasses of analytic functions of complex order defined by q-derivative operator. stud. university babes-bolyai math, 64(1); 71–80 © 2023 the authors. page 442 of 442 introduction results and discussion conclusion acknowledgment title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 3, july 2018 research paper synthesis of alkyd resin modified with waste palm cooking oil as precursor using pretreatment with zeolite adsorbent fitrilia silvianti1*, wijayanti wijayanti1, wisnu a.a. sudjarwo2, wikan berliana dewi1 1 politeknik atk yogyakarta, jl. ateka, bangunharjo, sewon, bantul, yogyakarta, indonesia 2 fakultas teknik, universitas setia budi, jl. letjend sutoyo mojosongo, surakarta, indonesia *corresponding author: fitrilia.s@atk.ac.id abstract research on synthesis of alkyd resin (ar) modified with waste palm cooking oil (wpco) as precursor using alcoholys-polyesterification method was successfully conducted. the modified alkyd resin was characterized using fourier transform infrared spectroscopy (ftir) and thermogravimetry-differential thermal analysis (tg-dta). the pretreatment was carried out for wpco by applying adsorption technique using zeolites to remove free fatty acid (ffa). modified alkyd resin was synthesized with the main ingredients composition consisting of wpco, glycerol, anhydrous phthalate with the oil length of 40% at the total weight of 27.54 grams, and a small amount of cao as catalyst. the characterization result using ftir showed the presence of typical alkyd resin compound group at the absorption peaks 1597.06 and 1651.07 consecutively as the vibration of benzene ring from the phthalate and c=c stretching of unsaturated fatty acids. the thermal characterization was performed by using tg-dta analysis showing that the transition glass and recrystallization at the temperature 390.25 ◦c and 482.46 ◦c respectively. keywords modified alkyd resin, waste palm oil, zeolites, adsorption received: 12 march 2018, accepted: 24 july 2018 https://doi.org/10.26554/sti.2018.3.3.119-122 1. introduction alkyd resin is an additive that serves as a binder in the paint industry, coating, plastic industry, adhesives, etc. alkyd resin is widely used in anti-corrosion coating industry, such as in automotives and shipbuilding industry. alkyd-based coating are well-known for good corrosion protection, high gloss, and the ease of application even over poorly teated surface (gan and tan, 2001). they are used for protecting surfaces against various environmental e�ects like uv-radiation, chemical invasion and mechanical stresses (oladipo et al., 2013). alkyd resin speci�cally can be called as a plasticizer in the manufacture of plastics. the use of alkyd resin is important in manufacturing industry to provide additional strength, �exibility, endurance, and other positive properties (momodu et al., 2011; atta et al., 2013; haryono et al., 2005). alkyd resins are unsaturated hydroxylated polyesters resins modi�ed with vegetables/marine oils or their fatty acid. therefore alkyd resins are main product of poly condensation reactions between poly carboxylic acids and poly alcohol in presence of fatty acids or vegetable oils (ibrahim et al., 2014). oil modi�ed alkyd resins are usually prepared via alcoholysis and polyesteri�cation of polyhydric alcohols and dibasic acids together with the modi�ying oils. the basic reaction of alkyd resin is esteri�cation, which shown below: r cooh + roh rcoor + h2o (1) alkyd resins used in industry are still dominated by derivative products from petroleum, especially the phthalate group. in fact, phthalates can be degraded into digestion, such as di-2-ethylhexyl phthalate (dehp) because alkyd resins from petroleum are less heat-resistant (haryono et al., 2005; waskitoaji et al., 2012). the petroleum based products are expected to decline in future years because their unrenewable properties. nowadays, some research are conducted to try �nding the subtitute of petroleum with renewable natural resources, such as plants and animals oils. several research studies have begun to switch to vegetable oil as a modi�ed alkyd resin substituent because it is considered safer, non-toxic, and biodegradable by having properties as alkyd resins similar to petroleum derivatives (haryono et al., 2005; waskitoaji et al., 2012; vaidya et al., 2012; galli et al., 2014). therefore , it is also important for companies to develop alternative sources which is decrease their production cost. alkyd resins modi�ed with vegetable oils have been produced in industries such as soybean oil, sun�ower seed oil, and https://doi.org/10.26554/sti.2018.3.3.119-122 silvianti et. al. science and technology indonesia, 3 (2018) 119-122 castor oil (haryono et al., 2005). alkyd resin contains agro (5070%) and petroleum (25%) base raw materials as compared to commercials resin contain 50-70% petroleum based products is highly hydrophilic, hence it can be used in emultion polymer synthesis (uzoh et al., 2013). the development of modi�ed alkyd resin using vegetable oil began to be expanded because of its good result compared to alkyd resin of petroleum oil, in addition to its better price and productivity. some research on the synthesis of alkyd resin using various vegetable oil precursors has shown the good results based on the parameters of alkyd resin properties. menkiti and onukwuli (2011) studied the relation between oil length variation and the properties of rubber-seed oil based alkyd resin products. in addition, igbo et al. (2014) examined the modi�cation of sesame oil-based alkyd resin. shaker et al. (2012) also did the research on jojoba oil-modi�ed alkyd resins according to the standard parameters of alkyd resin. meanwhile, isaac and nsi (2013) successfully synthesized cotton-based oil-based alkyd resins with polybasic acid variables. based on those studies on the precursor of alkyd resin, it can be concluded that alkyd resin can be produced using vegetable oil. vegetable oil industry, especially palm oil is a large industry in line with its use. a number of food industries consume a lot of cooking oil, such as crackers industry and restaurants potentially provide waste cooking oil. the post-processing of frying makes the cooking oil become harmful waste because it could cause damage to the liver, heart, and blood vessels as what was tested on wistar rats (rukmini, 2007). on the other hands, if wpco is disposed to the enviroment may cause large contamination. one of the way to utilize this waste palm cooking oil is to make it as a precursor for alkyd resin synthesis. in the synthesis process of alkyd resin, vegetable oil is often supplemented with a polyol compound, such as glycerol or pentaerythritol for the occurrence of an alkylolysis process that produces monoglycerides, before the alkyd resin esteri�cation process is carried out (menkiti and onukwuli, 2011; igbo et al., 2014). it is interesting that the heating process of cooking oil will trigger a hydrolysis process that produces glycerol and free fatty acids (aziz et al., 2013). therefore, glycerol from the used cooking oil will become polyols in the synthesis of alkyd resin by removing the product-free fatty acids from the hydrolysis of cooking oil �rst. however, the comparison of the results using additional glycerol in the alkoholys process is still required. the previous research, based on patent ep 1 984 420 b1, has succesfully synthesized a fat-based polymer using a glycerin-based alcoholic process. the process of removing free fatty acids from used cooking oil is done by adsorption technique using zeolite. based on us patent 6 229 032 b1 (p.a et al., 2001) and the previous research by taylor et al. (1984), the removal of free fatty acids using zeolites has already been conducted. in general, zeolites are crystalline aluminosilicates in which the three components, namely aluminium, silicon, and oxygen, are arranged in a �xed, dimensional framework with cavities and pores of uniformed size and shape. the zeolite network is composed of sio4 and alo4 tetrahedra in which the negative charge on the latter is neutralised by cations like metal ions, ammonium ions, or alkali metal ions. 2. experimental section 2.1 time and place of research this research was conducted from october 2016 until november 2016 at the laboratory of waste treatment politeknik atk yogyakarta. characterization of materials was conducted in the laboratory of instrumentation and polymer technology politeknik atk yogyakarta and laboratory of organic chemistry universitas gadjah mada. 2.2 materials and instrumentations materials used in this study were waste palm cooking oil taken from crackers home industry at bantul yogyakarta and zeolites adsorbent industrial grade. the chemicals were pure products of analytical quality, i.e. glycerol, anhydrous phthalate, cao, koh, ethanol 95%, xylene, phenolpthalein. the characterizations were done by ftir (shimadzu 8201pc) and tg-dta (perkin elmer diamond) under air atmosphere from 30 to 1000◦c at a heating rate of 10◦c.min−1. the equipments were used such as glassware, batch system equipment (three neck boiling �ask, glass condenser), magnetic stirrer, thermometer and shaker. 2.3 methods 2.3.1 pretreatment of wpco pretreatment of the waste palm cooking oil was conducted by applying adsorption method using 0.3 g zeolite in 150 ml cooking oil which was heated around 100 ◦c for 2 hours. the percentage of ffa was determined using aocs method with few modi�cation. fifty ml of ethanol were used to dissolve 2 g of sample and titrated against 0.1 n sodium hydroxide solution. ffa was expressed as palmitic acid 2.3.2 synthesis of alkyd resin the synthesis of alkyd resin was carried out with the main ingredients composition of cooking oil, glycerol, and anhydrous phthalate with an oil length of 40% and a total weight of 27.54 grams. in the synthesis process, the oil was mixed with glycerol and a small quantity of cao as a catalyst. this mixture was heated in a heating mantle at the temperature of 230-250 ◦c for 2 hours. to indicate the reaction, after two hours a little amount of aliquot was taken to check the solubility in methanol as a sign of the formation of monoglyceride. then, at the onset of the second phase, the temperature of reaction was lowered to 180 ◦c. anhydrous phtalate was added as dissolved in xylene by 10% of total weight charged of the mixture. aliquots were taken every 30 minutes to check the decrease in the number of acid. the reaction was stopped when the number of acid reached 10 mg koh g−1. the determination of acid amount used the procedure of aocs method. then, alkyd resin as the result was cooled and characterized with ftir. © 2018 the authors. page 120 of 122 silvianti et. al. science and technology indonesia, 3 (2018) 119-122 figure 1. ftir spectra of wpco (a) before adsorption; (b) after adsorption 3. results and discussion the pretreatment of wpco was done before the synthesis which used adsorption method with zeolite as the adsorbent to remove the free fatty acid. the adsorption was done in 150 ml wpco compounded with 0.3 g zeolite which was heated around 100 °c for 2 hours. after the adsorption, the % ffa was checked using aocs method, and the value was 0.003%. the characterization of wpco before and after the adsorption were analyzed using ftir. the ftir spectra shown in figure 1 illustrates the functional group of oil in general. it shows the peak of –oh at 3464.15 cm−1, c=o at 1743.65 cm−1, and –ch at 2924.09 cm−1. the ffa property is related to a large part of spectrum, such as the bands due to bonded o-h, c=o stretching in ester, c-h and the �ngerprint region of oil at 1500 – 1000 cm−1 (man, 1999). the qualitative result which was based on the ftir data demonstrated that the ffa in wpco after the adsorption was reduced compared to that in wpco before the adsorption. the intensity number of -oh, -c=o, and –ch bands before adsorption was higher compared to that after adsorption. besides, some of the bands in the �ngerprint of oil region were shifted. the characterization of alkyd resin and ftir in comparison to wpco after the adsorption is presented in figure 2. the ftir spectra showed the presence of a typical alkyd resin compound group at the absorption peak of 1597.06 cm−1 due to the vibration of benzene ring from the phthalate. it also occurred in the absorption at 1651.07 cm−1 because of the c=c stretching of the unsaturated fatty acids, as well as a characteristic of chain ester band at 1735.93 cm−1. the presence of o=c-o-c also exhibits the characteristic of ester bands at 1126.43 cm−1 (uzoh et al., 2013). the absorption of c-o alicyclic also appeared at 1072.42 cm−1. ftir spectra of wpco showed the vibration peak of stretching c=o from ester triglyceride group at 1743.65, while in alkyd resins spectra appeared in 1735.93. the absorption peak vibration of stretching oh, aliphatic c-h stretching and c-h bending appeared in both wpco and alkyd resin spectra at 3464.15 cm−1, 2924.09 cm-1, and 1458.18 cm−1. figure 2. ftir spectra of (a) wpco after adsorption; (b) alkyd resin modi�ed wpco figure 3. tg-dta thermogram of alkyd resin modi�ed wpco the thermal properties of ar was studied using tg-dta. about 9.981 mg of the sample was heated under the air atmosphere from 30 to 1000 °c at a heating rate of 10 °c. min−1. the tg-dta thermogram shown in figure 3 showed melting, recrystallisation and further melting. the transition glass and recrystallization occured at 390.25 °c and 482.46 °c respectively. thermogram tg-dta of ar showed the degradation at four stages. the �rst stage was at temperature 180 to 332.62 °c with the weight reduction of 22.368%. the second stage is endothermic reaction starting at 332.62 °c to 387.88 °c with the weight reduction of 60.669%. the third stage occured at temperature 387.88 °c to 429.27 °c and exothermic reaction with the weight reduction of 85.308%. the fourth stage was endothermic reaction which occured at temperature 429.27 to 498.53 °c with the weight loss 97.712%. the tga curve showed better degradation behavior of alkyd resin compared to alkyd resin based on pet waste and camelina sativa oil. alkyd resin based on pet waste has 75% weight loss at 375 °c (güçlü, 2009) and 70% weight loss at 388 °c (acar et.al, 2012). additionally, alkyd resin based on camelina sativa oil has 60% weight loss at © 2018 the authors. page 121 of 122 silvianti et. al. science and technology indonesia, 3 (2018) 119-122 398 °c (nosal et al., 2015). 4. conclusions the result has revealed that alkyd resin modi�ed with waste palm cooking oil precursor which was pretreated with zeolites adsorption technique could be synthesized by alcoholyspolyesteri�cation method. in general, the result of characterization showed the presence of a typical alkyd resin compound group at the absorption peak 1597.06 and 1651.07 as the vibration of benzene ring from the phthalate and c=c stretching of unsaturated fatty acids. references atta, a. m., r. a. el-ghazawy, and a. m. el-saeed (2013). corrosion protective coating based on alkyd resins derived from recycled poly(ethylene terephtalate) waste for carbon steel. int. j. electrochem, 8; 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(2007). regenerasi minyak goreng bekas dengan arang sekam menekan kerusakan organ (regeneration of used cooking oil with coal cha� to reduce organ damage). in proceeding seminar nasional teknologi, a1–a9 shaker, n. o., n. a. alian, and m. m. el-sawy (2012). preparation, characterization and evaluation of jojoba seed oil–modi�ed alkyd resins. der chemica sinica, 3(5); 1157–1162 taylor, d. r., c. b. ungermann, and z. demidowicz (1984). the adsorption of fatty acids from vegetable oils with zeolites and bleaching clay/zeolite blends. journal of the american oil chemists' society, 61(8); 1372–1379 uzoh, c., o. onukwuli, r. odera, and s. ofochebe (2013). optimization of polyesteri�cation process for production of palm oil modi�ed alkyd resin using response surface methodology. journal of environmental chemical engineering, 1(4); 777–785 vaidya, r., g. chaudhary, n. raut, g. shinde, and n. deshmukh (2012). synthesis of biocomposites from natural oil–a review. in proceeding of ipcbee, volume 41. page 55–60 waskitoaji, a., e. triwulandari, and a. haryono (2012). synthesis plasticizers derived from palm oil and their application in polyvynil chloride. in procedia chemistry, volume 4. page 313–321 © 2018 the authors. page 122 of 122 introduction experimental section time and place of research materials and instrumentations methods pretreatment of wpco synthesis of alkyd resin results and discussion conclusions title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 3, no. 2, april 2018 research paper analysis of vegetation in green open space of gasing industrial area siti indah oktaviani1*, laila hanum2, zaidan p negara3 1 postgraduate of environmental biology, sriwijaya university 2 biology fmipa sriwijaya university 3 faculty of agriculture sriwijaya university *corresponding author: sitiindahoktaviani@gmail.com abstract the study aims to determine the diversity of vegetation in the green open space of the gasing industrial area. the study was conducted from april to july 2017. the method of analysis used quadratic method with two plots at different location with three repetitions, quantitative data analysis was done on density value, dominance, frequency, important value and diversity index of each plant species. the results showed that vegetation consists of 16 tribes and 19 species, dominated by pteridophyta and spermatophyta. value of vegetation diversity (2,24) and uniformity value 0.30. the higher number of the species, the higher diversity index of the species. such characteristics are caused by environmental influences such as organic matter content and low ph and factors derived from human intervention. keywords vegetation, diversity, industrial area received: 12 january 2018, accepted: 25 march 2018 https://doi.org/10.26554/sti.2018.3.2.81-88 1. introduction south sumatra is currently experiencing rapid growth, one of them in the �eld of industry �eld. based on regional regulation of bayuasin no. 28 on the year of 2012, to support the industrial progress the government set gasing banyuasin area as an industrial and warehousing area because of the location is close to the provincial capital. gasing industrial and warehousing areas currently had already standing several factories such as, food industry, rubber, palm oil and gas. industrial development in gasing area aims to expand employment, leveling business opportunities, increasing exports, increasing foreign exchange, supporting regional development, utilizing natural resources and energy, and human resources. the development of industry in addition to positive impacts also have negative impacts on the surrounding environment such as, growth of settlement around the industrial area, tra�c jam, damaged of the protected areas, and decreased of the diversity of living things. according to the departemen industri (2007), food industry produces a lot of liquid and solid wastes. rahardjo and nugro (2009), the palm oil industry produces solid and liquid wastes, bahrin et al. (2011) rubber industry produces solid, liquid and gas wastes. if the wastes are above the standard in a long time will certainly have impacts on the presence of vegetation plants in place. vegetation is a complex system that interacts with various factors that in�uence each other. the existence of vegetation has a role and serves as a bu�er of life, protecting the water resources, soil, both in preventing erosion, and maintaining the global climate stability and acting as the lungs of the world and maintaining the environmental stability. vegetation will reduce the carbon in the atmosphere (co2) through the process of photosynthesis and store it in plant tissue. until the time carbon is re�uxed into the atmosphere, the carbon will occupy one of a number of carbon bags. all the components of vegetation such as trees, shrubs, lianas and epiphytes are part of the top the biomass surface (putri et al., 2012). to know the natural changes of the ecosystem in the area, it is necessary to do the data collection about the diversity of vegetation and then will be able to know the ability of the areas to generate the potential carbon before the land reclamation. this study aims to determine the diversity of vegetation in the green open space of gasing industrial area. 2. experimental section 2.1 location and time of the study the research was conducted in april july 2017, located in green open space of gasing industrial area, talang kelapa subdistrict, banyuasin regency (figure 1). https://doi.org/10.26554/sti.2018.3.2.81-88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 figure 1. location map (source bapeda banyuasin 2016) 2.2 research methods this research uses descriptive survey method with the aim to give a description about the vegetation in green open space of gasing industrial area. the sampling method was used the quadratic method which was consisted of two plots (locations). location 1 is in an area close to the waters with the coordinate point s 2 ° 48’27.9972”, e 104 ° 43’44,4” and location 2 is in the area far from the waters with the coordinate point 2 ° 52’37.5312” , e 104 ° 44’3.2388”. 2.3 tools and materials the tools were used in this research are scissors, transparent plastic, newspaper, wood/iron, cardboard cartons, corrugated aluminum, strap/belt, hanging label, scissors, a3 paper, tape, digital camera, bench mark, yarn, needles and stationery. 2.4 ways of working sampling was done by quadratic method. put 2 plots in different locations with three repetitions each plot. the size of the plots was 20 x 20 m for the tree, 10 x 10 m for the shrub, 5 x 5 m for the bushes, 2 x 2 m for herbs. in each plot, the data were taken are the name, numbers and tree canopy (cover area) of each plant species to determine the density, hump and frequency. plants which were found directly photographed in the area, specimens were collected include the form of plant specimens with complete body parts (roots, stems, leaves, �owers). plant samples were taken and labeled. the specimens’ collection based on the theory of anderson (1999). 2.5 identi�cation and classi�cation collected specimens were observed one by one by observing their morphology based on purwoko (1991). 2.6 data analysis quantitative analysis to determine the number of density, hump, frequency and important value was done using the calculation according to mueller-dombois and ellenberg (1984). for the index of diversity is calculated according to the shanonwiener’s diversity index (krebs, 1985). 2.6.1 density the results of the calculations gave an idea of the number of individuals in a particular area. this density was determined based on the number of individuals of a type divided by the map area, with the following formula: density = number of individuals area of the measurement plots (1) relativedensity = density of one type density of all types ×100% (2) 2.6.2 shade (domination) the shade was calculated to illustrate the extent of the covered area by a plant species in an area, and also to describe the extent of the area were being controlled by a plant species. dominance = the covered area by a species plot area (3) relative dominance = dominance of a species dominance of all species ×100% (4) 2.6.3 frequency the frequency is the percentage of the presence of a type, can be calculated by the formula: frequency = number of plots of a species discovery total number of plots (5) relative frequency = f requency of a species f requency of all species ×100% (6) © 2018 the authors. page 82 of 88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 important value is the sum of relative density, relative frequency and relative dominance, with the range values between 0 and 300 (mueller-dombois and ellenberg, 1984). (important value = relative density + relative frequency + relative dominance) the shanon-wiener’s diversity index that exhibits species diversity (putri, 1997) is calculated by the formula: h ′ =− ∑ ( ni n ) ln ( ni n ) (7) h ′ =− ∑ ( pi ) ln ( pi ) (8) where h ′ is shannon-wiener’s diversity index, ni is the number of individuals of a species, n is total number of individuals of all species, and pi = ni\n. the uniformity index is calculated by the formula: e = h ′ hmax × a (9) where e is uniformity index, h ′ is the diversity index, hmax is the maximum of uniformity index, as big as lns, and s is the number of family/species. 3. results and discussion the research was conducted on two di�erent plots (locations) in the green open space of gasing banyuasin industrial area. location 1 is an area close to the river �ow and location 2 is an area far from the river. at location 1 found 13 species of plants belonging to 13 families with individual numbers are 1,094 individuals (table 1). table 1 showed that the number of individuals belonging to trees has a greater number than the group of seedlings, bushes and shrubs. individuals are mostly found on acacia mangium species with individual numbers are 335 individuals, and then followed by melaleuca cajuputi which has 215 individuals. and plants that have the lowest number in the seedlings and herbs types are stenochlaena palustris bedd with 3 individuals and 6 individuals, in the level of shrubs, mikania sp with the number of 23 individuals and in the level of trees, cerbera odollam with the numbers of to 18 individuals. in location 2 found 14 plant species belonging to 10 families with an individual numbers of 1,203 individuals, shown in table 2. based on table 2 can be seen that most plants are clumps. individuals are mostly found on acacia mangium species with the individual numbers are 306 individuals, and then followed by melaleuca cajuputi which has 263 individuals. from the two tables 1 and 2 above it can be seen that there are di�erences in the types and number of plants found in locations 1 and location 2. tree-type plants more than herbs, bushes and shrubs (in table 1) whereas at location 2 the number and type of herbs and shrubs more than bushes and trees (in table 2). 3.1 important value index the result of the research at location 1 showed that the lowest relative density (kr) was found on cerbera odollam type at tree level which had value 0.3%, while the highest was found on herbs type was scleria sumatrensis with the value of 15.60%. the lowest relative dominance (dr) of the herbs species is lygodium sp. with a value of 0.05% and the highest tree species namely schima wallichii with the value of 19.83%. the lowest relative frequency was found in stenochlaena palustris bedd type is 0.28% and the highest found in acacia mangium species is 31.21%. the lowest important value index on the herbs species is stenochlaena palustris bedd with the value of 0.35%, while the highest was found in acacia mangium species at the tree level with a value of 38.01%. for more details can be seen in table 3. in location 2, the lowest relative density (kr) was found on lophopetalum at the tree level with the value of 0.13% while the highest was acacia mangium, shrub level, with the value of 14,48%. the lowest relative dominance (dr) is cyperus pulcherrimus at herb level with the value of 0,002% and the highest is lophopetalum at level of tree as big as 31,91%. the lowest relative frequency (fr) is cyperus pulcherrimus on herbs type as big as 0,30% and the highest is acacia mangium at 25,44%. the lowest importance value index is dioscorea hispida at bush level with 3.57% value. and the highest value is acacia mangium at the shrub level of 46.92% value. for more details can be seen in table 4. based on the data from tables 3 and 4 it can be presented from the important value of plant habitat that is in the location 1, the percentage of herbs as big as 1%, 5% bushes, 35% shrubs and 59% trees. while based on data from table 4, then it can be presented from the important value of plant habitat that is in the location 2, the percentage of herbs is 16%, 9% bushes, 45% shrubs and 30% trees. for more details can be seen in figure 2. density describes the number or the amount of individual types in a given area. this density is determined by the average number of individuals divided by the area of observation. meanwhile, the relative density is determined based on the density of a species divided by the density of the whole number of species and then multiplied by 100%. the highest relative density (kr) value at location 1 was found in scleria sumatrensis type with a value of 15.6% while the lowest in cerbera odollam at the tree level has a value of 0.3%. in the location 2, the highest relative density values was acacia mangium at the shrub level of 14.48% and the lowest value was lophopetalum at the tree level having a value of 0.13%. the high of the values indicate the number of species in each location. the variety of relative density values is due to the location conditions that have high environmental variations. © 2018 the authors. page 83 of 88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 table 1. types of plants found in location 1 of gasing banyuasin industrial areas species family average amount herbs / seedlings stenochlaena palustris bedd polypodiaceae 3 scleria sumatrensis cyperaceae 8 lygodium sp. lygodiaceae 4 dicranopteris linearis gleicheniaceae 7 bushes stenochlaena palustris bedd polypodiaceae 6 scleria sumatrensis cyperaceae 8 mikania sp. asteraceae 13 eupatorium inulifolium asteraceae 22 melastoma malabathricum melastomataceae 32 shrubs mikania sp. asteraceae 23 eupatorium inulifolium asteraceae 51 melastoma malabathricum melastomataceae 48 melaleuca cajuputi myrtaceae 49 acacia mangium fabaceae 50 trees melaleuca cajuputi myrtaceae 215 acacia mangium fabaceae 335 dillenia excelsa dilleniaceae 131 lophopetalum celast raceae 19 schima wallichii theaceae 33 cerbera odollam apocynaceae 18 total 1074 according to loveless (1989), some plants can successfully grow in diverse environmental conditions so the plants tend to be widespread. plants that occupy the highest density due to these plants are suitable for life and breed in the conditions of the land and the environment where the soil and the water contain a low ph. while in plants that have the lowest density, it is presumably because the land and the environmental factors are less suitable as a place for the species to grow, especially the ph of water and soil is acidic (low). domination describes the extent of cover or part of the land that is dominated by plants. the dominant value of a plant species is obtained by looking at the percentage of area covered or dominated by the plant species. the highest relative dominant value at location 1 is occupied by schima wallichii type of 19.83%, whereas the lowest is herbs type of lygodium palmatum with value of 0,05%. at location 2 the highest value was occupied by lophopetalum type with the value of 31.91% at tree level and the lowest was cyperus pulcherrimus at the herbs level with value of 0.002%. the value of dominant relative shows the proportion between the areas covered by the plant species with the total area of the habitat and indicates the dominant plant species in the community (irwanto, 2007). according to odum (1993), the dominant species have large productivity, and in determining the dominant vegetation species, it should be known the diameter of the stems. the presence of dominant species at the research site becomes an indicator that the community is in an appropriate habitat and supports its growth. frequency describes the distribution or the spreading and the presence of a plant species to an area. frequency can be calculated from the appearance of each plant species in each plot. the calculation is determined based on the number of plots that were being observed and then multiplied by 100%. based on the value of fr can be seen the proportion between the number of a species with the number of other types in the community and can described the distribution of individuals within the community. the distribution and growth of individual trees is strongly in�uenced by seeding power, topography of soil conditions and other environmental factors. the seeds of trees scattered in areas that are poor in organic matter and with excessive light intensity such as those found in the green open areas of the gasing industry can be bad and deadly for the growth of the seed. the highest relative frequency (fr) value at location 1 is acacia mangium of 31.21%, while the © 2018 the authors. page 84 of 88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 table 2. types of plants found in location 2 of gasing banyuasin industrial areas species family average amount herbs / seedlings lygodium sp. lygodiaceae 9 lygodium palmatum lygodiaceae 6 cyperus pulcherrimus cyperaceae 4 eleocharis dulcis cyperaceae 4 scleria sumatrensis cyperaceae 7 dicranopteris linearis gleicheniaceae 7 bushes mikania sp. asteraceae 27 eupatorium inulifolium asteraceae 14 melastoma malabathricumê melastomataceae 21 dioscorea hispida dioscoreaceae 10 shrubs mikania sp. asteraceae 91 eupatorium inulifolium asteraceae 79 melastoma malabathricumê melastomataceae 104 melaleuca cajuputi myrtaceae 263 acacia mangium fabaceae 306 trees melaleuca cajuputi myrtaceae 99 acacia mangium fabaceae 122 dillenia excelsaê dillenia excelsaê 17 lophopetalum lophopetalum 11 total 1203 lowest in stenochlaena palustris bedd type is 0.28%. in location 2, acacia mangium was grown at 25.44%, while the lowest was cyperus pulcherrimus on herbs type of 0.30%. from these values it can be seen that the highest frequency value in both locations is acacia mangium widely found in green open areas of gasing industrial area. these types can adapt to environmental conditions so that plants have the ability to spread. as a result, the presence of this type can be found in every area of observation. in addition, it was supposed that this plant have the ability to compete with other plants so that the distribution is relatively more evenly than other types. the homogeneous environment, ph and organic macro elements in these lands are suspected to support for the growth and development of this plant species. according to senoaji (2009), this type breeds quickly with seeds. such the way of breeding is thought to contribute to the ability of plant species to spread. frequency of presence is often expressed by constancy. the constancy or frequency of the presence of the organism can be grouped into four groups: the accidental type (frequency 025%), the accessory type (frequency 25-50%), the constant type (frequency 50-75%), and the absolute type (frequencies above 75 %) (suin, 2002). based on the above data it can be seen that most of the green open areas of the gasing industry are included in the accidental category (fr 0-25%). this showed that the types distribution in the limited areas, and spreading of the seeds only in the vicinity of the forest where it grows. monk et al. (2000), states that trees that grow below to the optimum height, generally rely on the supply of seeds from the higher trees. an important value index of a plant species determines the role of the plant species in the plant community. the essential value of each plant species is determined based on the relative amount of density, relative dominance and relative frequency. based on table 3, the �rst and second highest importance index were found on the acacia mangium species at the tree level with a value of 37.44% and melaleuca cajuputi 25.90%. and in table 4, the �rst and second highest importance value indexes are acacia mangium at the shrub level of 49.59% and melaleuca cajuputi at the shrub level of 39.57%. according to dombois and ellenberg (1974), the name of the family of the type with the �rst and second largest importance values can represent the characteristics of the local vegetation so that it can be used to name the vegetation of the area. so, based to the importance value there is no di�erence between plant species in location 1 and location 2, it is only di�er in group © 2018 the authors. page 85 of 88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 (a) (b) figure 2. graph of the species number of each habitat in (a) location 1, and (b) location 2 table 3. important location value index 1 in green open space of gasing industrial area species family amount kr dr fr inp herbs / seedling stenochlaena palustrisêbedd polypodiaceae 3 5.9 0.07 0.28 0.35 scleria sumatrensis cyperaceae 8 15.6 0.06 0.74 0.8 lygodium sp. lygodiaceae 4 8.5 0.05 0.4 0.45 dicranopteris linearis gleicheniaceae 7 13 0.13 0.62 0.75 bushes stenochlaena palustrisêbedd polypodiaceae 6 1.8 0.91 0.53 1.44 scleria sumatrensis cyperaceae 8 2.4 0.7 0.71 1.41 mikania sp. asteraceae 13 4 0.91 1.18 2.09 eupatorium inulifolium asteraceae 22 7 0.51 2.08 2.59 melastoma malabathricumê melastomataceae 32 9.9 1.15 2.95 4.1 shrubs mikania sp. asteraceae 23 1.8 13.59 2.17 15.77 eupatorium inulifolium asteraceae 51 4 9.97 4.75 14.72 melastoma malabathricumê melastomataceae 48 3.7 11.33 4.44 15.77 melaleuca cajuputi myrtaceae 49 3.9 12.24 4.59 16.83 acacia mangium fabaceae 50 3.9 12.69 4.69 17.37 trees melaleuca cajuputi myrtaceae 215 4.2 5.89 20.01 25.9 acacia mangium fabaceae 335 6.6 6.8 31.21 38.01 dillenia excelsaê dilleniaceae 131 2.6 8.5 12.22 20.72 lophopetalum celastraceae 19 0.4 14.5 1.74 16.24 schima wallichii theaceae 33 0.6 19.83 3.04 22.87 cerbera odollam apocynaceae 18 0.3 11.9 1.64 13.54 total 1074 100 100 100 300 © 2018 the authors. page 86 of 88 oktaviani et. al. science and technology indonesia, 3 (2018) 81-88 table 4. important location value index 2 in green open space of gasing industrial area species families amount kr dr fr inp herbs / seedlings lygodium sp. lygodiaceae 9 11.04 0.33 0.78 12.14 lygodium palmatum lygodiaceae 6 7.49 0.12 0.53 8.14 cyperus pulcherrimus cyperaceae 4 4.34 0.002 0.3 4.64 eleocharis dulcis cyperaceae 4 4.73 0.1 0.33 5.16 dicranopteris linearis gleicheniaceae 7 7.88 0.28 0.55 8.72 bushes mikania sp. asteraceae 27 5.11 0.91 2.24 8.26 eupatorium inulifolium asteraceae 14 2.65 1.99 1.16 5.81 melastoma malabathricumê melastomataceae 21 4.04 2.52 1.77 8.33 dioscorea hispida dioscoreaceae 10 1.96 0.78 0.86 3.59 shrubs mikania sp. asteraceae 91 4.32 4.49 7.59 16.4 eupatorium inulifolium asteraceae 79 3.75 3.44 6.59 13.78 melastoma malabathricumê melastomataceae 104 4.94 4.87 8.67 18.48 melaleuca cajuputi myrtaceae 263 12.44 5.27 21.86 39.57 acacia mangium fabaceae 306 14.48 7.01 25.44 46.92 trees melaleuca cajuputi myrtaceae 99 1.17 3.44 8.26 12.87 acacia mangium fabaceae 122 1.45 21.47 10.17 33.09 dillenia excelsaê dillenia excelsaê 17 0.21 10.95 1.44 12.6 lophopetalum lophopetalum 11 0.13 31.91 0.89 32.92 total 1203 100 100 100 300 table 5. index of diversity and uniformity location diversity index uniformity index 1 2.24 0.32 2 2.02 0.29 habitat in location 1. the highest important value index in the tree group is 59% (�gure 1) whereas at location 2 the highest important value index in the group of shrubof 47% (�gure 2). 3.2 index of diversity and uniformity based on research at locations 1 and 2, were obtained the diversity index which was found at location 1 as big as 2.24 and location 2 as big as 2.02 while for uniformity index of location 1 was 0.32 and location 2 was 0.29. for more details can be seen in table 5. based on table 5, it can be seen that there is no big difference between location 1 and location 2 for diversity and uniformity index. according to mason (1980), if the value of the diversity index is smaller than 1 it means there were low species diversity, if the index between 1-3 it means medium species diversity, if greater than 3 it means high species diversity. the higher number of species, the higher diversity index of the species. high species diversity is an indicator of the growth environments stability. high stability indicates a high level of complexity; this is due to the high interaction so it will have a higher ability in the face of interference to its components. 4. conclusions from the results of this research that has been done in the green open space of gasing industrial area can be drawn the following conclusions: 1. the diversity of swamp vegetation composed by spermatophyta and pteridophyta consists of 16 families and 19 species. 2. based on the importance values and diversity index it can be seen that vegetation is diverse and evenly distributed with a low level of uniformity. 3. the condition of the vegetation caused by the environmental in�uences, which contain organic matter and low ph and factor derived from human intervention. 5. acknowledgement references anderson, l. 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(2009). kontribusi hutan lindung terhadap pendapatan masyarakat desa di sekitarnya: studi kasus di desa air lanang bengkulu (contribution of protected forest on income people in the village surrouttdings: case study in air lanang, bengkulu, sumatera, indonesia). jurnal manusia dan lingkungan, 16(1); 12–22 © 2018 the authors. page 88 of 88 introduction experimental section location and time of the study research methods tools and materials ways of working identification and classification data analysis density shade (domination) frequency results and discussion important value index index of diversity and uniformity conclusions acknowledgement title science and technology indonesia e-issn:2580-4391 p-issn:2580-4405 vol. 8, no. 3, july 2023 research paper synthesis, characterization, and antibacterial activity of some mesalazine derivatives ekhlas qanber jasim1, munther abduljaleel muhammad-ali2*, ayad almakki3 1department of pathological analyses, college of science, university of basrah, basrah, 61004, iraq2department of ecology, college of science, university of basrah, basrah, 61004, iraq3department of laboratory sciences, college of pharmacy, university of basrah, basrah, 61004, iraq *corresponding author: munther.ali@uobasrah.edu.iq, muntheralamery@yahoo.com abstractmesalazine, often referred to as mesalamine or 5-aminosalicylic acid (5-asa), and its derivatives are some of the first medications tobe approved for treating digestive tract inflammations, including ulcerative colitis and mild to moderate crohn’s disease. sulfasalazine,discovered in 1938 for therapeutic use, was the first mesalazine derivative. high yields of four different mesalazine derivatives weresynthesized, including two schiff bases and two azo compounds. the present study involved the synthesis of schiff bases throughthe reaction of mesalazine with pyrrole-2-carbaldehyde or indole-2-carbaldehyde, resulting in the formation of 5-(((1h-pyrrol-2-yl)methylene)amino)-2-hydroxybenzoicacid(1)or5-(((1h-indol-2-yl)methylene)amino)-2-hydroxybenzoicacid(2), respectively. thesynthesis of azo compounds involved the coupling of mesalazine with sulfamethoxazole or pyridoxine, resulting in the formation of5-amino-2-hydroxy-3-((4-(n-(5-methylisoxazol-3-yl)sulfamoyl)phenyl)diazenyl)benzoic acid (3) or 2-hydroxy-5-((5-hydroxy-3,4-bis(hydroxymethyl)-6-methylpyridin-2-yl)diazenyl)benzoic acid (4), respectively. the identification of the synthesized compoundswas carried out using ir and 1h-nmr spectroscopy. antibacterial assessment of the synthetic compounds was performed in vitroagainst gram-negative bacteria (such as escherichia coli and pseudomonas aeruginosa) and gram-positive bacteria (staphylococcus aureus). the antibacterial activity studies demonstrated that against escherichia coli and staphylococcus aureus, the schiff basecompounds are more active than azo compounds. compound 1 showed the highest activity, resulting in a 23 mm inhibition zoneagainst e. coli at 1000 `g/ml. in contrast, the antibacterial activity of compound 2 was observed to be 25 mm against s. aureus atthe same highest concentration. keywordsmesalazine, schiff bases, azo compounds, antibacterial activity, modification of drug received: 18 january 2023, accepted: 17 april 2023 https://doi.org/10.26554/sti.2023.8.3.338-343 1. introduction modifying the chemical molecules of commercially available medications is one of the most critical aspects of pharmacological development. molecular modification involves changing the chemical structure of drugs away from their active site, which can impact their efficacy and ability to treat certain diseases. thus, a new derivative of the drug molecule is prepared using different chemical reactions with physicochemical properties other than the original drug (ye and van langenberg, 2015) . the substance mesalazine, used to treat inflammatory bowel diseases like crohn’s disease and ulcerative colitis, is one essential medicine whose chemical structure has undergone modifications (yasutomi et al., 2019) . mesalazine has additional biological activities; it has been utilized as an antioxidant against oxygen and nitrogen free radicals (yousefi et al., 2017) , anti-ulcer (beiranvand, 2021) , against colorectal cancer (dixon et al., 2021) , and antimicrobial activity (zhang et al., 2018; cevallos et al., 2021). several pharmaceutical dosage forms of mesalazine derivatives are utilized in the drug market to treat uc, focusing on aminosalicylic acids and their associated derivatives. the most important derivatives are salazosulfapyridine (sasp), olsalazine, and mesalazine (zhang et al., 2015) . the chemical structure of mesalazine is of great importance in the process of chemical modification on this molecule, as it contains in its structure two groups, carboxyl and amine groups, and these two groups are easily subject to many types of chemical reactions, allowing the formation of many types of derivatives (yuri et al., 2020) . within the design of prodrugs as derivatives of the drug mesalazine, many polysaccharides were used by linking them using ester bonds of the carboxyl group because they are considered non-toxic. through the polysaccharide compounds, it is possible to observe the mutation in the characteristics of these compounds through their https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.338-343&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.338-343 jasim et. al. science and technology indonesia, 8 (2023) 338-343 absorption from the small intestine; it is also soluble in water (sardo et al., 2019) . the other type of modification is on the amino group, and the prodrugs of mesalazine can be prepared by linking them with amino acids. based on these functional groups, amino acids can be connected via an ester (yousefi et al., 2015) or amide bond, and an azo group (abdel alim et al., 2005) can be synthesized. in particular, when an amide bond is used, the synthesized compound is similar in structure to a dipeptide (monbaliu, 2016; taheri-ledari et al., 2022; tosi et al., 2022). in this study, four synthesized mesalazine derivatives were tested for their potential antibacterial activity against two types of gram-positive and gram-negative bacteria. two are derivatives of schiff bases (1 and 2), and the other are derivatives of azo dyes (3 and 4). 2. experimental section 2.1 materials the reagents and solvents utilized in this study were of reagentgrade quality and were procured from merck and sigma-aldrich. solid materials were used without additional purification, while liquid materials were subjected to double distillation. the gallenkamp thermal point apparatus was utilized to determine the uncorrected melting points. the ftir 8400s shimadzu ( japan) was utilized to record infrared spectra in kbr pellets at basrah university’s college of science. dmso-d6’s 1h-nmr spectra were measured at 500 mhz using a bruker ac 200 ft-nmr spectrometer with tms as an internal reference, (greece). the chn elemental analyzer flashes ea 1112 series was utilized to conduct the elemental microanalysis (chn) on the synthesized compounds, (thermo finnigan). 2.2 methods 2.2.1 synthesis of compounds schiff bases synthesis 5-(((1h-pyrrol-2-yl)methylene)amino)2-hydroxybenzoic acid (1) and 5-(((1h-indol-2-yl)methylene) amino)-2-hydroxybenzoic acid (2): in the mixture that contained 0.01 mole (1.51 g) of 5amino salicylic acid that had been dissolved in 15ml of ethanol, 0.01 mole of either pyrrole-2-carboxaldehyde or indol-2-carbo xaldehyde that had also been dissolved in 15 ml of ethanol was added, and then 1 ml of glacial acetic acid was added to the mixture. the mixture was stirred continuously for sixty minutes at room temperature. to get rid of any unreacted substances, the yellow precipitate that formed, as a result, was filtered out and then washed with cold methanol. ethanol was used to recrystallize the products that were the result (vhanale et al., 2019; warad et al., 2020). (1): a pale yellow crystal was obtained with a yield of 90%. the melting point was within the range of 187-189 °c. the infrared spectrum of the compound, obtained using kbr, showed absorption bands at 3305 cm−1 (o-h), 3010 cm−1 (c-h, aromatic), 1687 cm−1 (c=n, azomethine), 1606 cm−1, and 1508 cm−1 (c=c), as well as at 1253 cm−1 and 1145 cm−1 (c-n, co). the 1h nmr spectrum of the compound in dmso-d6 solution displays signals at 𝛿 = 12.80 (broad, 1h, carboxylic acid), 10.39 (singlet, 1h, hydroxyl), 9.25 (singlet, 1h, amine), 8.61 (singlet, 1h, imine), and a range of signals between 6.53 and 8.13. (m, 6h, ar-h). anal. calc. (found) for c12h10n2o3 (230.22): c, 62.61 (61.95); h, 4.38 (4.54); n, 12.17 (12.32). (2): crystal in a dark yellow color, with a yield of 92%, melting point in the range of 174-176 degrees celsius, and the following ir (kbr) spectrum: v (cm−1) = 3386 (o-h), 3010 (c-h, aromatic), 1656 (c=n, azomethine), 1600, 1510 (c=c), 1238, 1165 (c-n, c-o). 1h nuclear magnetic resonance (dmsod6): = 6.92-7.90 (m, 8h, ar-h), 8.84 (s, 1h, ch=n), 8.99 (br, 1h, nh), 10.25 (s, 1h, oh), 12.69 (br, 1h, cooh). anal. calc. (found) for c16h12n2o3 (280.28): c, 68.56 (67.87); h, 4.32 (4.22); n, 9.99 (10.21). the present study involves the synthesis of two compounds, namely 5-amino-2-hydroxy-3-((4-(n-(5-methylisoxazol-3yl)sulfamoyl)phenyl)diazenyl) benzoic acid (3) and 2-hydroxy5-((5-hydroxy-3,4-bis(hydroxymethyl)-6-methylpyridin-2-yl) diazenyl)benzoic acid(4). diazotization was accomplished by dissolving 0.025 mol of 5-aminosalicylic acid or sulfamethoxazole in 5 ml of 2 m hydrochloric acid. after that, the solution was placed in an ice bath until it reached a temperature of 0-5 degrees celsius, then kept at that temperature. a solution of sodium nitrite (5 mol, 2 g) in water (5 ml) was added drop by drop while the mixture was continuously stirred for ten minutes at the same temperature. general procedure for preparation of azo dyes: the coupling reaction was performed by gradually adding the diazonium solution of 5-aminosalicylic acid or sulfamethoxazole to the coupling component solution, which had been prepared by combining a suspension of one mmol of pyridoxine (0.2056 g) or one mmol of 5-aminosalicylic acid (0.253 g) (scheme 1) in 10 ml of water with sodium hydroxide (0.002 mmol) dissolved in 15 ml of water. during this procedure, the ph was between 9 and 10, while the temperature was maintained at 0 to 5 degrees celsius. the mixture was agitated for 6 hours, and the ph was lowered to about six. overnight, the mixture was kept. filtration was used to collect the precipitated crude dyes, which were then washed with solvents such as water, ethanol, and acetone (benkhaya et al., 2020; kareem samad, 2017). (3): powdered orange, 80% yield; melting point below 306 degrees celsius; infrared (kbr) spectral lines: v (cm−1) = 3412 (o-h), 1591 (c=n), 1511 (c=c), 1463 (n=n), 1300 (c-h, aliph), 1174, 1091 (c-n, c-o). for the hydrogen atom(1h) in dmso-d6, the nmr spectrum looks like this: = 12.56 (br, 1h, cooh), 10.40 (s, 1h, oh), 11.20 (br, 1h, nh), 6.868.02 (m, 7h, ar-h), 5.36 (s, 2h, nh2), 1.91 (s, 3h, ch3). anal. calc. (found) for c17h15n5o6s (417.40): c, 48.92 (48.67); h, 3.62 (3.52); n, 16.78 (16.61). (4): the color is dark purple, the yield is 85%, the melting point is below 350 degrees celsius, and the infrared spectrum looks like this: ir (kbr): v (cm−1) = 3425 (o-h), 1645 (c=n), 1500 (c=c), 1587 (n=n), 1384 (c-h, aliph), 1272 (c-n, c-o). 1h nmr (dmso-d6): 𝛿 = 12.77 (br, 1h, cooh), 10.35 © 2023 the authors. page 339 of 343 jasim et. al. science and technology indonesia, 8 (2023) 338-343 (s, 1h, oh), 9.79 (s, 1h, oh pyridoxine), 7.25-7.86 (m, 3h, ar-h), 5.63 (s, 2h, oh aliphatic), 4.21 (s, 4h, ch2), 2.37 (s, 3h, ch3). anal. calc. (found) for c15h15n3o6 (333.30): c, 54.05 (54.32); h, 4.54 (4.42); n, 12.61 (12.71). 2.2.2 antibacterial evaluation pathogenic strains of gram-positive (staphylococcus aureus) and gram-negative (escherichia coli and pseudomonas aeruginosa) were used to investigate the antibacterial activity of the prepared compounds using the filter paper disc diffusion method (kifby-bauer method). this method measured the inhibition zone in mm around these bacteria. a dimethyl sulfoxide solvent was used to prepare a stock solution of 1000 `g/ml for each compound, which was subsequently stored at 4-8 °c until utilized. the mueller hinton agar plates were inoculated using a sterile cotton swab dipped into the inoculum. the swab was then evenly streaked in three directions across the entirety of the petri-dish surface. discs of filter paper measuring 6 mm in diameter were saturated with a solution of tested compounds at a concentration of 1000 mg/ml and various other diluted concentrations. the impregnated discs were subsequently dried and positioned onto an agar plate inoculated with gram-positive and gram-negative bacteria cultures (salman, 2019; mohammed-ali and jasim, 2019). figure 1. compounds one and two synthesis 3. results and discussion 3.1 chemistry the synthesis of two products (1 and 2) was achieved by condensing the 5-aminosalicylic acid compound with pyrrole-2carboxaldehyde or indol-2-carboxaldehyde in refluxed ethanol solvent, with the addition of a tiny amount of glacial acetic acid. the resulting yellow crystals were analyzed using ir spectroscopy, revealing significant absorption broad bands at v 3305 and 3386 cm−1 for compounds (1) and (2), respectively. these bands were due to the vibrations caused by stretching of o-h for phenolic and carboxylic groups, as depicted in figure 1. the appearance of a distinct band at 1658 and 1656 cm−1 (bartyzel, 2017) (for compounds 1 and 2, respectively) is indicative of the c=n vibrations that stretch the azomethine fragment, thereby providing compelling evidence for the formation of schiff bases. four singlet signals were found in the 1h-nmr spectrum of compound (1). two of these signals referred to hydroxyl groups of carboxylic and phenol of salicylic fragment at 𝛿 12.80 figure 2. compound three synthesis figure 3. compound four synthesis and 10.39 ppm, respectively (kleks et al., 2021) . the h-n bond in the pyrrole ring and the ch=n bond in the azomethine group was responsible for two additional signals at 𝛿 9.25 and 8.61 ppm, respectively (jasim et al., 2020) . the multiple signals observed at the 6.53-8.13 ppm range for six protons corresponded to the aromatic protons of pyrrole and salicylic rings. figure 4. spectrum of 1h-nmr compound 2 singlet signals were observed in the 1h-nmr spectrum of compound 2 at 𝛿 12.69 and 10.25 ppm. these signals were ascribed to the salicylic acid fragment’s phenolic hydroxyl and carboxylic hydroxyl protons. another two singlet signals were observed at chemical shifts of 𝛿 8.99 and 8.84 ppm, attributed to the n-h of indole and ch=n of the azomethine group, respectively. figure 4 shows several aromatic signals between 𝛿 6.92 and 7.90 ppm, caused by the eight indole and salicylic acid group protons. aromatic amines react with concentrated hcl and sodium nitrite at 0-5 °c to produce diazonium salts. sulfamethoxazole or 5-aminosalicylic acid subjected to diazotization process to give the corresponding diazonium salts. another step in the © 2023 the authors. page 340 of 343 jasim et. al. science and technology indonesia, 8 (2023) 338-343 synthesis of an azo compound is coupling reaction with rich electron aromatic system, diazonium salt of sulfamethoxazole reacts with 5-aminosalicylic acid to give the azo compound (3). azo compound (4) was synthesized by reaction of diazonium salt of 5-aminosalicylic acid with pyridoxine with characteristic bright colored crystals, as shown in figure 2 and 3. figure 5. (a) iz of compound (1) against e. coli, (b) iz of compound (4) against s. aureus figure 6. inhibition zone of the studied compounds against s. aureus the ir spectra of the azo compounds gave broad peaks at the range about v 3400 cm−1 due to stretching vibration of o-h of carboxylic group overlapped with phenolic group. another characteristic strong-medium peak attributed to stretching vibration of azo group appeared at 1463 and 1587 cm−1 for compound (3) and (4), respectively. 1h-nmr of the compound (3) gave two singlet signals in download field at 𝛿 12.56 and 10.40 ppm attributed to hydroxyl group of carboxylic and phenolic groups, respectively. another singlet signals at 𝛿 11.20 ppm attributed to n-h proton of amide in sulfa fragment and at 𝛿 5.36 ppm due to two protons of nh2 group in salicylic fragment. aromatic protons gave multiplet signals at the range 𝛿 6.86-8.02 ppm referred to seven protons in each sulfa and salicylic fragments, and finally, singlet signal at highfield range 𝛿 1.91 ppm attributed to three protons of methyl group, as shown in table 1. the 1h-nmr analysis of compound 4 yielded a complex spectrum featuring two singlet signals at 𝛿 12.77 and 10.35 ppm, which were attributed to the hydroxyl proton of the figure 7. inhibition zone of the studied compounds against e. coli figure 8. inhibition zone of the studied compounds against p. aeruginosa phenolic and carboxylic groups, respectively. a singlet signal at 𝛿 9.79 ppm was also observed, which was attributed to a single phenolic proton of the pyridoxine group. multiplet signals at 𝛿 6.62-7.37 ppm referred to three protons of salicylic ring, singlet signal 𝛿 5.63 ppm due to two protons of aliphatic alcohol, singlet signal referred to four aliphatic protons of two groups of methylene in -ch2-oh fragment in pyridoxine ring at 𝛿 4.21 ppm, finally, as shown in table 1, the singlet signal at 𝛿 2.37 corresponds to the three protons of a methyl group in the pyridoxine ring. 3.2 antibacterial sensitivity test the activity of the synthesized compound was assessed through the disc diffusion method utilizing various concentrations (125, 250, 500, and 1000 `g/ml) while using dmso as a control. the results were then compared to the standard drug mesalazine. against s. aureus bacteria, compound (2) and (4) showed higher activity (25 and 19 mm, respectively) as compared other compounds. against e. coli bacteria, the compounds (1, 2 and 4) gave strong inhibition zone (23, 18 and 19 mm, respectively) as compared with other compounds, as shown in figure 5. the synthesized compounds exhibited considerable efficacy compared to the standard mesalazine drug, potentially due to the bacteria’s resistance to the commercial © 2023 the authors. page 341 of 343 jasim et. al. science and technology indonesia, 8 (2023) 338-343 table 1. 1h-nmr synthetic compound’s data compounds 𝛿 (ppm) -cooh -oh -nh -ch=n aromatic others 1 12.80 (s) 10.39 (s) 9.25 (s) 8.61 (s) 6.53-8.13 (m) 2 12.69 (s) 10.25 (s) 8.99 (s) 8.84 (s) 6.92-7.90 (m) 3 12.56 (s) 10.40 (s) 11.20 (s) 6.86-8.02 (m) 5.36 (s) -nh2, 1.91 (s) -ch3 4 12.77 (s) 10.35 (s) 7.25-7.86 (m) pyridine ring, 9.79 (s) -oh, 5.63 (s) aliph. -oh, 4.21 (s) -ch2-, 2.37 (s) -ch3 ppm: part per million, s: singlet signal, m: multiplet signal table 2. in vitro antibacterial sensitivity test of synthesized compounds in dmso concentration s. aureus e. coli p. aeruginosa (`g/ml) iz (mm) compound (1) 1000 16 23 11 500 10 19 8 250 nil 15 nil 125 nil 11 nil iz (mm) compound (2) 1000 25 18 14 500 20 12 10 250 17 9 nil 125 12 nil nil iz (mm) compound (3) 1000 12 10 nil 500 8 8 nil 250 nil nil nil 125 nil nil nil iz (mm) compound (4) 1000 19 19 12 500 15 17 7 250 10 17 nil 125 8 14 nil iz (mm) mesalazine 1000 nil 14 12 500 nil 8 8 250 nil nil nil 125 nil nil nil drug. overall view on the activity, the best activity is 23 mm attributed to (1) against e. coli and 25 mm for compound (2) against to s. aureus, as shown in figure 6-8. table 2 represents the data of in vitro antibacterial activity of synthesized compounds in dmso. schiff bases with a salicylic-imine moiety are also effective in the mechanism of inhibition on bacterial growth. compounds 1 and 2 belonging to this category of schiff bases exhibited complete growth inhibition against s. aureus and e. coli (tyagi et al., 2017; kumar and bansal, 2021). regarding p. aeruginosa, the highest antibacterial activity was detected by compound 2 with a minimum zone of inhibition of about 14 mm which was the weakest inhibition zone among other studied bacteria, moreover, p. aeruginosa shows complete resistance to compound 3 whatever its concentration was. 4. conclusion the schiff bases, denoted as compounds 1 and 2, and the azo compounds, designated as compounds 3 and 4, were successfully synthesized with high yield and purity. subsequently, spectroscopic techniques were employed to characterize these compounds. the inhibition zone method evaluated the synthesized compounds’ antibacterial sensitivity. compounds 1, 2, and 4 demonstrated intense activity against s. aureus and e. coli, while compound 3 exhibited moderate activity. the bacteria p. aeruginosa showed high resistance against the synthesized compounds. the standard drug mesalazine showed weak activity under the same experimental conditions, which referred to the high resistance of all three strains of bacteria to this known drug. another finding from this study is that the ability of synthesized compounds to inhibit bacterial growth increased with increased concentration. 5. acknowledgment the authors thank the department of pathological analyses within the college of science at the university of basra for their valuable support and guidance. references abdel alim, a. m., abdel, a. n. a. el shorbagi, s. g. abdel moty, and h. h. m. abdel allah (2005). synthesis and anti-inflammatory testing of some new compounds incorporating 5-aminosalicylic acid (5-asa) as potential prodrugs. archives of pharmacal research, 28; 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recycling in seremban, malaysia through decision-making trial and evaluation laboratory (dematel) analysis zahari md rodzi1*, ashiera nadiha hazri1, nurul ain syahirah mohd azri1, nurul dania farisha sharul rhmdan1, zati aqmar zaharudin1, saladin uttunggadewa2 1mathematical sciences studies, college of computing, informatics and media,universiti teknologi mara (uitm),negeri sembilan branch, seremban campus, seremban, negeri sembilan, 70300, malaysia2pusat pemodelan matematika dan simulasi (p2ms) institut teknologi bandung and combinatorial matematics research group, faculty of mathematics and natural sciences, institut teknologi bandung, gedung labtek iii lantai 1, jalan ganesha no. 10, bandung, 40132, indonesia *corresponding author: zahari@uitm.edu.my abstractthisstudyinvestigatesthebarrierstohouseholdwasterecycling inseremban, malaysia, usingthedecision-makingtrialandevaluationlaboratory (dematel) analysis. the research questions aimed to identify and rank the most significant barriers to recycling andunderstand the causal relationships between them. the study found that limited access to recycling facilities and services andlack of motivation or incentive to recycle were the most significant causes of household waste recycling barriers in seremban. onthe other hand, lack of motivation or incentive to recycle and negative attitudes towards recycling, were identified as the mostsignificant effects. the study’s findings have theoretical implications for waste management and sustainable development and offerpractical implications for policymakers and waste management practitioners in developing effective waste management strategiesand policies that can address these barriers. furthermore, the study’s insights into the most significant barriers to household wasterecycling can inform the design of recycling campaigns and educational programs to increase awareness and promote householdwaste recycling in seremban. overall, this study provides a valuable contribution to the field of waste management and sustainabledevelopment and offers insights into the challenges of promoting household waste recycling in urban areas. keywordswaste management, recycling, household waste, barriers, decision-making, dematel, seremban, malaysia received: 7 march 2023, accepted: 13 june 2023 https://doi.org/10.26554/sti.2023.8.3.422-428 1. introduction waste recycling has emerged as a crucial tactic in sustainable waste management, aiming to reduce landfill waste, conserve natural resources, and foster environmental preservation (ayeleru et al., 2023) . the aim of this research is to examine the barriers to waste recycling by means of a comprehensive review of literature and expert insights, followed by an assessment of the decision-making trial and evaluation laboratory (dematel) methodology in appraising these obstacles in the context of seremban, malaysia. the present investigation aims to address two distinct research inquiries: rq1: what are the key factors that influence household waste recycling in seremban, malaysia, and how do they relate to each other? rq2: what are the most significant barriers that prevent households in seremban, malaysia from engaging in waste recycling, and how do these barriers interrelate? the present study aims to attain its research objectives by utilizing the dematel method to scrutinize and determine the crucial factors and impediments associated with waste recycling in seremban, malaysia. the utilization of dematel analysis presents a thorough and methodical methodology for comprehending the intricate interconnections between the various factors and hindrances (garg, 2021) . this approach offers valuable discernment into prospective policies and practical solutions that can effectively surmount these obstacles and promote household waste recycling (favot et al., 2022) . according to statistics provided by the department of national solid waste management ( jpspn), malaysia’s recycling rate for the year 2020 was documented at 31.52%, which fell short of the government’s target of attaining a recycling rate of 40% by 2025. in contrast, a significant proportion of developed countries have attained a recycling rate of at least 60%. the imperative to surmount barriers that impede recycling endeavors in malaysia and enhance communal engagement in https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2023.8.3.422-428&amp;domain=pdf https://doi.org/10.26554/sti.2023.8.3.422-428 rodzi et. al. science and technology indonesia, 8 (2023) 422-428 recycling programs is of utmost significance. the findings of a research study that elucidate the barriers to waste recycling are presented in table 1. despite the challenges, malaysia has implemented various measures aimed at promoting recycling and reducing waste. the government at the national level launched a program called "kampungku bersih" (my clean village) to promote communal responsibility for waste management and encourage the adoption of recycling practices. private sector initiatives, such as the take-back program for pre-owned furniture by ikea malaysia and the tzu chi foundation’s dispersed recycling centers that cater to a wide range of recyclable materials, are aimed at promoting recycling practices and reducing waste. the icycle platform has been implemented in malaysia as a supplementary initiative to promote the recycling of domestic waste. the government of malaysia has initiated a campaign aimed at promoting sustainable practices and addressing the issue of waste management, which is referred to as the "zero waste" campaign. table 2 provides a comprehensive summary of recycling activities in seremban, focusing on the quantity of recycling materials collected in different sectors such as schools, kindergartens, communities, government offices, universities, and industries. the table includes the weight of the recycled materials measured in kilograms (kg) as well as their corresponding monetary value in ringgit malaysia (rm). over the course of five years, from 2017 to 2021, a significant amount of recycling materials was collected. the recycling bank in schools yielded a total of 313,180 kilograms, with a corresponding value of rm 68,185. similarly, the recycling bank in kindergartens contributed 20,768 kilograms of recyclables, amounting to rm 4,998. the community recycling bank collected a total of 59,297 kilograms of materials, valued at rm 17,100. government offices in seremban also actively participated in recycling, resulting in the collection of 124,109 kilograms of recyclables, with a value of rm 24,339. furthermore, universities in the area contributed 13,137 kilograms of recycling materials, which were valued at rm 2,049. the recycling efforts in industries were notable as well, with a total collection of 249,398 kilograms, amounting to rm 24,212. 2. experimental section the study’s first stage involved a research methodology that encompassed a thorough examination of published articles and reports related to household waste recycling. the aim of the literature review was to determine the previously identified and researched barriers to household waste recycling. in addition to performing a comprehensive literature review, the researchers engaged in discussions with experts in the fields of waste management and recycling to gather their insights on the barriers to household waste recycling in seremban. the second phase of the study involves gathering data from experts who have at least a decade of experience in waste management within the seremban region of malaysia. the expert panel was composed of an academic, a government official, figure 1. research methodology framework a representative from the waste management industry, and a member of a non-governmental organization specializing in household waste recycling. semi-structured interviews were conducted with the experts. the interview questions were designed to elicit expert opinions on the barriers that impede household waste recycling in seremban. the evaluators were tasked with assessing the degree of correlation between each obstacle, utilizing a likert scale that ranged from 1 to 5. the scale’s values ranged from "not related" at 1 to "highly related" at 5. the study utilized the decision-making trial and evaluation laboratory (dematel) methodology to analyse the data. this technique enables the investigation of causal relationships among variables. the experts’ ratings on the barriers were employed in the development of a dematel matrix. the matrix enabled the discernment of the causal connections that exist among the hindrances. the study employed the dematel software to conduct a matrix analysis and identify the main barriers to household waste recycling in seremban. the findings were then validated by experts. if the experts are content with the causal diagram and result analysis, they will be presented. however, if they are dissatisfied, the data collection process will be repeated. the figure 1 shows the research methodology framework for this study. figure 1 depicts the research methodology framework employed in this study. the steps involved in the dematel method are as follows: step 1. creating the matrix of direct influence the first step involves the creation of a direct relationship matrix, where xki j represents an integer score k assigned by an expert. this metric indicates the degree of impact that criterion i has on criterion j. the matrix a of dimension n×n , as presented in equation (1), the computation of household waste recycling scores involves the utilisation of an averaging process that incorporates the individual evaluations of three distinct experts, namely an academician, an industry specialist, and a government representative. table 3 presents the dematel binary comparison scale that was utilised. aj j = 1 h h∑︁ k=1 xki j (1) © 2023 the authors. page 423 of 428 rodzi et. al. science and technology indonesia, 8 (2023) 422-428 table 1. the barriers to waste recycling barriers references b1-negative attitudes towards recycling almasi et al., 2019; ayeleru et al., 2023; babaei et al., 2015; byrne and o’regan, 2014; corrado et al., 2022; gilli et al., 2018; padilla and trujillo, 2018; karaktekin et al., 2023; king et al., 2023; lau et al., 2021; malibari et al., 2023; vijayan et al., 2023; wu et al., 2021; yadav et al., 2022 b2-limited storage space for recyclable materials at home li et al., 2020a; lu et al., 2022; luthra et al., 2023; matsumoto, 2011; nguyen et al., 2022 b3-inconvenient or inconsistent recycling collection schedules de moraes et al., 2022; dias et al., 2022; shuvo, 2023; tsimnadis et al., 2023 b4-lack of awareness and understanding of the benefits of recycling almulhim, 2022; chengqin et al., 2022; jacobsen et al., 2022; ghaedrahmati et al., 2023; helmefalk et al., 2023; mousa, 2020; nguyen et al., 2022; azme et al., 2023; reijonen et al., 2021; shah and rezai, 2023; shaikh et al., 2020; tian et al., 2022; vijayan et al., 2023; zhong et al., 2022 b5-limited access to recycling facilities and services dutta and goel, 2021; gu et al., 2022; maiurova et al., 2022; wang et al., 2021b; zaharudin et al., 2022; zhang et al., 2016 b6-lack of motivation or incentive to recycle cheng et al., 2022; chengqin et al., 2022; li et al., 2020b; li et al., 2022; wang et al., 2021a; xu et al., 2023; yang and thøgersen, 2022; zhong et al., 2022; zhou et al., 2021 b7-lack of enforcement or penalties for non-compliance with recycling regulations ayeleru et al., 2023; favot et al., 2022; li et al., 2022; ma et al., 2020; woodard, 2020 h: number of experts. step 2. normalising of the matrix of direct influence formulas (2) and (3) are used to get the normalised directrelation matrix s from matrix a. s = k.a (2) k = min ( 1 max1≤i≤n ∑n j=1[ai j]′ 1 max1≤ j≤n ∑n i=1[ai j] ) (3) i, j ∈ (1, 2, ..., n) step 3. constructing the matrix of complete relations after normalising the direct-relation matrix s, the total-relation matrix m is computed using the formula (4), where i denote the identity matrix: m = s(i − s)−1 (4) step 4. the development of a cause-and-effect diagram the utilisation of c + r and r − c is demonstrated in formula (5) to (7) for matrix m, where r represents the sum of columns and c represents the sum of rows. criteria that exhibit positive r−c values exert a stronger influence on the remaining criteria. the term "dispatchers" is commonly used to refer to these individuals. individuals with lower r−c levels tend to be more susceptible to external influences. the entities are commonly denoted as "receivers." conversely, the summation of r and c denotes the extent of correlation between one criterion and the rest. m = [mi j]n×n i, j ∈ (1, 2, ..., n) (5) ri = n∑︁ j=1 [mi j]n×1 = [mi]n×1 (6) ci = n∑︁ i=1 [mi j]1×n = [mj]1×n (7) step 5. obtaining the matrix of internal dependencies and the map of effect relationships the dataset was mapped utilising the (r + c, r − c). the parameter known as the threshold value is employed to denote the degree of influence present between a set of criteria. © 2023 the authors. page 424 of 428 rodzi et. al. science and technology indonesia, 8 (2023) 422-428 table 2. summary of recycling activities in seremban year recycling bank recycling bank recycling bank recycling bank in recycling bank recycling bank in school in kindergarden in community government office in university industry kg rm kg rm kg rm kg rm kg rm kg rm 2017 45,608 9,488 8,803 2,213 2,522 576 41,127 12,899 6,262 1,249 224,767 17,647 2018 45,226 9,389 4,092 898 5,547 845 11,069 1,391 2,458 34 3,345 14 2019 74,048 16,154 4,042 1,015 7,001 1,306 5,385 1,455 1,171 144 2,417 5,123 2020 96,018 20,181 2,590 551 6,227 1,066 26,677 4,974 1,018 185 14,596 860 2021 52,279 12,974 1,242 320 38,001 13,307 39,851 3,620 2,229 437 4,272 568 total 313,180 68,185 20,768 4,998 59,297 17,100 124,109 24,339 13,137 2,049 249,398 24,212 table 3. linguistic term linguistic terms influence score unrelated 1 slightly unrelated 2 moderately related 3 related 4 very related 5 3. results and discussion this section presents the findings of the dematel analysis, which provided significant insights into the main barriers to household waste recycling in seremban and their underlying root causes. the study proposed effective interventions for mitigating barriers through recognizing causal relationships among them. the objective of this research is to elucidate the key outcomes of the dematel analysis and their significance in advancing the practice of household waste recycling in seremban. table 4 displays the prominence and net cause/effects of this study. the variable exhibiting the greatest r +c value of 10.9256 within the table pertains to "limited access to recycling facilities and services", indicating a noteworthy impact on recycling behavior. the recycling behavior of individuals can be influenced by various factors. among these factors, insufficient awareness and comprehension of the benefits of recycling, with a r + c value of 10.3973, inconvenient or irregular recycling collection timetables, with a r + c value of 10.0067, and inadequate motivation or incentive to recycle, with a r + c value of 10.6433, are noteworthy. the variables that demonstrate a lower r + c score, specifically "negative attitudes towards recycling" with a r + c score of 9.2361 and "lack of enforcement or penalties for non-compliance with recycling regulations" with a r + c score of 9.2680, exhibit a noticeable impact, albeit to a relatively lesser extent. mitigating these factors can generally aid in overcoming obstacles to recycling and promoting the adoption of environmentally responsible waste management practises. this influence diagram aids in figure 2 visualizing the cause-and-effect relationship among barriers to waste recycling in seremban. insufficient availability of recycling infrasfigure 2. waste recycling barrier’s criteria influence diagram tructure and services, coupled with inadequate knowledge and comprehension of the advantages of recycling, are significant contributing factors that can impact the recycling conduct of individuals. the restricted availability of recycling facilities and services may potentially lead to a decrease in recycling behavior among individuals, as the inconvenience and difficulty in locating a nearby recycling centre can act as a deterrent. this phenomenon may result in the disposal of recyclable materials in the conventional waste stream. the deficiency in knowledge and comprehension regarding the advantages of recycling can potentially result in a decreased inclination among individuals to engage in recycling practices. insufficient understanding of the advantages of recycling could lead to a decreased recognition of the significance of participating in recycling activities, ultimately lowering the probability of individuals taking the extra step to recycle their materials. inadequate understanding may lead to uncertainty regarding the categorization of recyclable and non-recyclable materials, which can further contribute to individuals’ hesitancy to engage in recycling. the interdependence between these two factors may potentially impact the remaining obstacles outlined in the table. the lack of access to recycling facilities and services may poten© 2023 the authors. page 425 of 428 rodzi et. al. science and technology indonesia, 8 (2023) 422-428 table 4. prominence and net cause/effects barriers r c r+c r-c identify b1-negative attitudes towards recycling 4.2517 4.9844 9.2361 -0.7327 effect b2-limited storage space for recyclable materials at home 4.7308 4.6358 9.3666 0.095 cause b3-inconvenient or inconsistent recycling collection schedules 5.0172 4.9894 10.0067 0.0278 cause b4-lack of awareness and understanding of the benefits of recycling 5.8796 4.5177 10.3973 1.3619 cause b5-limited access to recycling facilities and services 5.7631 5.1625 10.9256 0.6006 cause b6-lack of motivation or incentive to recycle 4.8764 5.7669 10.6433 -0.8906 effect b7-lack of enforcement or penalties for non-compliance with recycling regulations 4.403 4.865 9.268 -0.4619 effect tially decrease individuals’ motivation and incentives to engage in recycling practices. furthermore, irregular recycling collection timetables could potentially worsen the issue, thereby increasing the challenge of recycling for individuals. hence, tackling these two underlying factors could potentially play a pivotal role in enhancing recycling conduct and augmenting the overall recycling percentages. the initiatives may encompass endeavors aimed at enhancing the availability of recycling facilities and services, alongside educational endeavors designed to augment comprehension and recognition of the advantages associated with recycling. the absence of strict implementation or sanctions for nonadherence to recycling policies may result in diminished impetus or inducement to engage in recycling activities. this is because individuals may perceive little value in expending additional effort towards recycling when there are no repercussions for non-compliance. if individuals do not observe a substantial influence of their actions or the lack of repercussions for abstaining from recycling practices, they may develop a belief that the activity lacks value and is not worth their time and energy. a decrease in recycling rates due to a lack of motivation can have negative consequences on the environment. thus, the implementation of recycling regulations and the imposition of penalties for non-compliance can serve as effective measures to encourage individuals to engage in recycling practices and foster favorable recycling conduct. 4. conclusion to summarize, the present study utilized the dematel analysis methodology to identify the hindrances to household waste recycling in seremban, malaysia. this research undertaking conducted a comprehensive analysis of academic literature, consulted with experts, and scrutinized the causal relationships among the identified obstacles. the results underscore the significant obstacles that impede household waste recycling in the region, such as insufficient recycling infrastructure, absence of motivation, and restricted incentives. this study has noteworthy practical implications for waste management professionals and policymakers. the promotion of a recycling culture in seremban can be facilitated by policymakers through the identification and addressing of barriers, including the enhancement of recycling infrastructure and the implementation of incentive programmers. furthermore, promoting consciousness and cultivating favorable dispositions towards recycling can potentially enhance engagement in domestic waste recycling. the endeavors are of paramount importance in attaining sustainable waste management targets and conforming to the recycling rate objectives set forth by the government. 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