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 mate- rials 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 electroposi- tive 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 com- posting 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 spe- cic 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, in- cluding 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 pollu- tants because it has many advantages such as eco-friendly, eco- nomic 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 or- ganic pollutants. Juleanti et al. (2021) conducted a study by https://crossmark.crossref.org/dialog/?doi=10.26554/sti.2022.7.4.461-468&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 com- pared 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 thermo- dynamic 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 hex- acyanoferrate (III) (K3[Fe(CN)6]), buer solution pH 10, HCl, and NaOH. The synthesized material was characterized us- ing an X-Ray Rigaku Miniex-600 diractometer, Shimadzu Prestige-21 FTIR Spectrophotometer, BET Surface Area Ana- lyzer Micrometric ASAP Quantachrome, and absorbance mea- surement of solution using Biobase Spectrophotometer UV- Visible 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 tempera- ture 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 copre- cipitation 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 adsor- bent 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 dirac- tion at Zn/Cr-LDH appeared at angles of 11.74° (003), 23.49° (006), 34.33° (009), 39.26° (012) and 60.41° (110) accord- ing 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 lay- ered 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/Cr- C 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/Cr- C 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 FT- IR 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 IU- PAC classication with the presence of particles of mesoporous size with hysteresis activity. Hysteresis activity shows the ma- terial has non-uniform pores, so that the graph between ad- sorption 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 char- acterization 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 com- posites 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 kinet- Figure 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 ini- tial concentration and temperature on the phenol adsorption process. Basedongure7, it isknownthat themoretheconcen- tration and temperature increase, the adsorbed concentration also increases. From the test of the inuence of the initial con- centration 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 indi- Figure 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 mate- rial. 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 mate- rials 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 success- fully 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 authors thank to Research Center of Inorganic Materi- als and Coordination Complexes, Faculty of Mathematics and Natural Sciences, Sriwijaya University for support and instru- mental analysis. REFERENCES Alminderej, F. M., A. M. Younis, A. E. Albadri, W. A. El- Sayed, Y. El-Ghoul, R. Ali, A. M. Mohamed, and S. M. Saleh (2022). The Superior Adsorption Capacity of Phenol from Aqueous Solution Using Modied Date Palm Nanoma- terials: A performance and Kinetic Study. Arabian Journal of Chemistry, 15(10); 104120 Chaghaganooj, Z. D., N. Asasian-Kolur, S. Sharian, and M. Sillanpää (2021). Ce and Mn/bio-waste-based Activated Carbon Composite: Characterization, Phenol Adsorption and Regeneration. Journal of Environmental Chemical Engi- neering, 9(4); 105788 da Silva, M. C., C. Schnorr, S. F. Lütke, S. Knani, V. X. Nasci- mento, É. C. Lima, P. S. Thue, J. Vieillard, L. F. Silva, and G. L. Dotto (2022). KOH Activated Carbons from Brazil Nut Shell: Preparation, Characterization, and Their Appli- cation in Phenol Adsorption. Chemical Engineering Research and Design, 187; 387–396. Debnath, B., P. Duarah, D. Haldar, and M. K. Purkait (2022). Improving the Properties of Corn Starch Films for Applica- © 2022 The Authors. Page 467 of 468 Wijaya et. al. Science and Technology Indonesia, 7 (2022) 461-468 tion as Packaging Material Via Reinforcement with Micro- crystalline Cellulose Synthesized from Elephant Grass. Food Packaging and Shelf Life, 34; 100937 Dehbi, A., Y. Dehmani, H. Omari, A. Lammini, K. Elazhari, S. Abouarnadasse, and A. Abdallaoui (2020). Compara- tive Study of Malachite Green and Phenol Adsorption on Synthetic Hematite Iron Oxide Nanoparticles (𝛼-Fe2O3). Surfaces and Interfaces, 21; 100637 Dehmani, Y., D. Dridi, T. Lamhasni, S. Abouarnadasse, R. Ch- tourou, and E. C. Lima (2022). Review Of Phenol Adsorp- tion On Transition Metal Oxides And Other Adsorbents. Journal of Water Process Engineering, 49; 102965 Dehmani, Y., O. El Khalki, H. Mezougane, and S. Abouar- nadasse (2021). Comparative Study on Adsorption of Cationic Dyes and Phenol by Natural Clays. Chemical Data Collections, 33; 100674 Dehmani, Y., L. Sellaoui, Y. Alghamdi, J. Lainé, M. Badawi, A. Amhoud, A. Bonilla-Petriciolet, T. Lamhasni, and S. Abouarnadasse (2020). Kinetic, Thermodynamic and Mechanism Study of the Adsorption of Phenol on Moroc- can Clay. Journal of Molecular Liquids, 312; 113383 Dong, F.X., L. Yan, X.H. Zhou, S.T. Huang, J.Y. Liang, W.X. Zhang, Z.W. Guo, P.-R. Guo, W. Qian, L.-J. Kong, et al. (2021). Simultaneous Adsorption of Cr (VI) and Phenol by Biochar-based Iron Oxide Composites in Water: Per- formance, Kinetics and Mechanism. Journal of Hazardous Materials, 416; 125930 Gao, W., Z. Lin, H. Chen, S. Yan, H. Zhu, H. Zhang, H. Sun, S. Zhang, S. Zhang, and Y. Wu (2022). Roles of Graphiti- zation Degree and Surface Functional Groups of N-doped Activated Biochar for Phenol Adsorption. Journal of Analyti- cal and Applied Pyrolysis, 167; 105700 Hernández-Barreto, D. F., L. Giraldo, and J. C. Moreno- Piraján (2020). Dataset on Adsorption of Phenol Onto Ac- tivated Carbons: Equilibrium, Kinetics and Mechanism Of Adsorption. Data in Brief, 32; 106312 Ingole, R. S., D. H. Lataye, and P. T. Dhorabe (2017). Ad- sorption of Phenol Onto Banana Peels Activated Carbon. KSCE Journal of Civil Engineering, 21(1); 100–110 Juleanti, N., N. R. Palapa, T. Taher, N. Hidayati, B. I. Putri, and A. Lesbani (2021). The Capability of Biochar-based CaAl and MgAl Composite Materials as Adsorbent for Re- moval Cr (VI) in Aqueous Solution. Science and Technology Indonesia, 6(3); 196–203 Keshvardoostchokami, M., M. Majidi, A. Zamani, and B. Liu (2021). Adsorption of Phenol on Environmentally Friendly Fe3O4/Chitosan/Zeolitic Imidazolate Framework- 8 Nanocomposite: Optimization by Experimental Design Methodology. Journal of Molecular Liquids, 323; 115064 Liu, J., J. Li, X. Bing, D. H. Ng, X. Cui, F. Ji, and D. D. Kionga (2018). ZnCr-LDH/N-Doped Graphitic Carbon- incorporated g-C3N4 2D/2D Nanosheet Heterojunction with Enhanced Charge Transfer for Photocatalysis. Materials Research Bulletin, 102; 379–390 Lupa, L., L. Cocheci, R. Pode, and I. Hulka (2018). Phenol Adsorption usingAliquat 336 Functionalized Zn-Al Layered Double Hydroxide. Separation and Purication Technology, 196; 82–95 Mohammad, Y., E. Shaibu-Imodagbe, S. Igboro, A. Giwa, and C. Okuofu (2014). Adsorption of Phenol from Renery Wastewater Using Rice Husk Activated Carbon. Iranian (Iranica) Journal of Energy & Environment, 5(4) Padalkar, N. S., S. V. Sadavar, R. B. Shinde, A. S. Patil, U. M. Patil, D.S.Dhawale, R.N.Bulakhe, H.Kim, H.Im, A.Vinu, et al. (2022). Layer-by-layer Manohybrids of Ni-Cr-LDH Intercalated with 0D Polyoxotungstate for Highly Ecient Hybrid Supercapacitor. JournalofColloidandInterface Science, 616; 548–559 Safwat, S. M., N. Y. Mohamed, M. N. Meshref, and A. Elawwad (2022). Adsorption of Phenol onto Aluminum Oxide Nanoparticles: Performance Evaluation, Mechanism Exploration, and Principal Component Analysis (PCA) of Thermodynamics. Adsorption Science & Technology, 2022 Sahu, J., R. R. Karri, and N. Jayakumar (2021). Improvement in Phenol Adsorption Capacity On Eco-friendly Biosorbent Derived From Waste Palm-oil Shells Using Optimized Para- metric Modelling of Isotherms and Kinetics by Dierential Evolution. Industrial Crops and Products, 164; 113333 Saleh, T. A., S. O. Adio, M. Asif, and H. Dafalla (2018). Statis- tical Analysis of Phenols Adsorption on Diethylenetriamine- modied Activated Carbon. Journal of Cleaner Production, 182; 960–968 Sani, D. E., J. O. Idoko, E. S. Okwute, and M. C. Apeh (2020). Adsorption of Phenol Onto Unactivated Moringa Oleifera Seed Shells Residue byUV-visible Spectrophotometer. GSC Biological and Pharmaceutical Sciences, 13(2); 080–090 Sun, J., Y. Wang, Y. He, J. Liu, L. Xu, Z. Zeng, Y. Song, J. Qiu, Z. Huang, and L. Cui (2022). Eective Removal of Nanoplastics from Water by Cellulose/MgAl Layered DoubleHydroxidesCompositeBeads. CarbohydratePolymers, 298; 120059 Ullah, N., Z. Ali, S. Ullah, A. S. Khan, B. Adalat, A. Nasrul- lah, M. Alsaadi, and Z. Ahmad (2022). Synthesis of Ac- tivated Carbon-surfactant Modied Montmorillonite Clay- alginate Composite Membrane for Methylene Blue Adsorp- tion. Chemosphere; 136623 Wang, X., B. Cheng, L. Zhang, J. Yu, and I. Normatov (2022). Adsorption Performance of Tetracycline on NiFe Layered Double Hydroxide Hollow Microspheres Synthesized with Silica as the Template. Journal of Colloid and Interface Science, 627; 793–803 Yuliasari, N., Badri, A. F., Wijaya, A., Mega, P., Bahar, S., Siregar, N., and Mohadi, R. (2022). Modication of Mg/Al- LDH Intercalated Metal Oxide (Mg/Al-Ni) to Improve the Performance of Methyl Orange and Methyl Red Dyes Ad- sorption 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