مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Adsorption of Thymol From Aqueous Solution Using Granulated Surfactant Initiated Modified Bentonite via Packed Column Method M. H. Abdul Latif, A. K. Mahmood and M. A. Al - Abayaji Department of Chemistry, Ibn Al Haitham College of Education, University of Baghdad Received in : 16 June 2011 Accepted in :18 October 2011 Abstract The adsorption study of thymol, was carried out at (25±0.1) °C, using granulated surfactant modified Iraqi Na – montmorillonite clay (initiated modified bentonite); in a down-flow packed column, the modified mineral was characterized by FT-IR spectroscopy. A linear calibration graph for thymol was obtained, which obey Beer's law in the concentration range of 5-50 mg/L at 274 nm against reagent blank. Single-factor-at-a-time approach; showed that the equilibrium time required for complete adsorp tion was 45 minute with flow rate (4.0drop/ mint). The adsorption of thymol increased with rising pH of the adsorbate solution, increase of solute uptake when the initial adsorbate concentration is increased. The adsorption is mostly physically in nature and fitted with Langmuir model. The result indicated that the pseudo-second-order kinetic models is fitted very well with the experimental data. Keywords : adsorption, thymol, Na – montmorillonite, clay, packed column. Introduction Phenolic compounds are the most important contaminants present in the environment. It can be originated naturally due to the degradation of humic substances, tannins, lignins and many of environment processes, These compounds are used in several industrial processes to manufacture chemicals such as pesticides, explosives, drugs and dyes. They are also used in the bleaching process of paper manufacturing. Apart from these sources, phenolic compounds have substantial applications in agriculture as herbicides, insecticides and fungicides [1, 2]. Thymol (Scheme1) is phenolic monoterpene, isolated from Thymus vulgaris, Origanum vulgare, Satureja thymbra and Thymbra capitata plants [3] , confers antimicrobial properties to these oils. In addition, this phenolic compound is currently used in conjunction with chlorhexidine to inhibit oral bacteria. It has been postulated that thymol decreases enzyme activity and/or disrupts membrane integrity by altering protein reactions [4]. Studies have shown that thymol inhibits Gram-positive and Gram-negative bacteria and possess multiple biological properties such as anti-inflammatory, anti-leishmanial, antioxidant [5], hepatoprotective and anti-tumor activities [6]. It have been shown to be an efficient acaricide molecule against the Varroa destructor, an external parasitic mite that attacks honey bees [7]. Many methods are used for determination of thymol such as liquid chromatographic methods by making a comparison between the use of a silica-based monolithic column and a RP- Amide C16 column for the separation of phenol, thymol and carvacrol [8], NM R [9] and HPTLC [10]. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 CH3 H3C CH3 OH Scheme 1: The chemical structure of thymol Clays are hydrated alumino silicates, composed of mixture of fine-grained minerals, crystals of other minerals and oxides. Natural mineral clays possess specific surface chemical properties, e.g., cation exchange capacity , and adsorptive affinity for some organic and inorganic compounds, which have led to investigate on the potential use of clays as adsorbents for treating heavy metals and organic pollutants, or as coagulant aids for improving the settling performance in coagulating low particle content water. By replacing the natural inorganic exchange cations with alkyl ammonium ions, clay surfaces are converted from being primarily hydrophilic to hydrophobic, which enable them to interact strongly with organic vapors and organic compounds dissolved in water [11]. Clays obtaining montmorillonite are referred to bentonite which belongs to the 2:1 clay family composed of two tetrahedrally coordinated sheet of silicon surrounding an octahedrally coordinated sheet of aluminum ions [12].While the number of Al ions in tetrahedral sites determines the net negative charge of the host layer, which can adopt a number of interesting stacking arrangements to form ordered, partially ordered, or disordered three-dimensional structures. Another interesting feature of clay is swelling [13], indicating that the interlayer of some clay can reversibly incorporate amounts of polar molecules, such as water and cations. Much attention has been drawn to the modification of clay mineral properties, because it has low cost and readily available in several technological applications [14]. Clays can be modified to increase the attenuation of some organic compounds and improve its sorp tion ability. Since hydration of exchangeable alkali and alkaline earth metal cations creates a hydrophilic environment on the surface and in the interlayer region of natural clays[15]. The adsorbent properties can be improved by replacing the natural inorganic cations with organic cations such as quaternary ammonium cations of the (CH3)3N + (CH2)15CH3 form. The main purpose of such modification is to increase the hydrophobic nature of the mineral surface and consequently enhance the affinity towards organic compounds. Organo clays show different hydrophobic properties depending on the organic cations structure and its uptake into the gallery. This is an important feature because the treatment of the mineral can be adjusted according to need [16]. Another very important attribute when clay modification is proposed for organo clay is the cation exchange capacity (CEC). Vermiculite and bentonite are clay minerals with high CEC. The CEC for vermiculite, for instance, is approximately 100– 150 meq per 100 g [15]. West Iraqi (Traifawi) bentonite consists mostly of calcium – montmorillonite. The percent of montmorillonite is between (60 – 65 %) of crude bentonite, table (1) shows the chemical analysis of West Iraqi (Traifawi) bentonite, therefore it is necessary to remove the impurities before the bentonite is ready to use. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Apparatus A Cintra 5 spectrophotometer with 1 cm quartz cells was used for absorbance measurements. Sartorius BL 210S (±0.0001g)scientific balance, scientific shaker with thermal control(GCA precision), pH-meter DW-9421 from Philips instrument, a glass column (70 cm X 15 mm i.d.) and Pentium 4 computer (DELL 1545) was used for data processing. Experimental Material and Reagents All Chemicals used were of analytical reagent grad unless otherwise is mentioned, bentonite mineral clay obtained from the General Company for Geological Survey and Mining in Baghdad; Iraq, thymol crystal (Riedel- De Haen). Standard solution Thymol stock solution (250 mg/L ), was prepared by dissolving 0.025gm of thymol in 5ml ethanol and diluting to 100 ml in volumetric flask with distilled water. Working solutions were freshly prepared by subsequent dilutions. General Recommended procedure for determination of thymol 1 ml aliquots of thymol standard solution containing (25-250 mg/L) were transferred into a series of 5 ml volumetric flask; and diluted with distilled water. Measure the spectrum at 274nm against a reagent blank prepared similarly without addition of thymol. Procedure for synthesis of granulated surfactant modified Iraqi Na – montmorillonite clay a. Initiation In this study the bentonite was beneficiated to improve its Smectite (Montmorillonite) content by attrition – scrubbing at high solid concentration (50%) and at high impeller speed (2500 r.p.m.) for 1 h, using flotation cell. Then is converted calcium - montmorillonite to sodium - montmorillonite by process of activation using ion-exchange technique, by mixing the bentonite preconcentrate with Na – form activated amberlight orange ion exchanger followed by agitation for 1 h, at 150 r.p.m[17]. The clay was separated from the mixture by filtration, washed about five times with distilled water. Each washing step involved stirring the slurry in distilled water, followed by centrifugation and removal of the supernant, then Na – monmorillonite was treated with 0.5 M NaCl to ensure complete transformation to the Na – form , then the treated clay was washed with distilled water to remove excess NaCl[17] . b. Modification Then the sodium-form montmorillonite was modified with a surfactant Hexadecyltrimethyl ammonium bromide (HDTMA) to form organic modified clay ready to use in our research, it was done by adding (50 m mol/L) solution of (HDTMA) TO A 7% aqueous clay suspension. The mixture was stirred in a mixer for 3h, at 350 r.p.m. The organic modified clay was separated from the mixture by filtration and washed about five times with distilled water[18]. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 c. Granulation The organic modified montmorillonite turned to a granules of (2mm) diameter using granulating machine (GK Dry Granulating Machine) and dried at 110 ºC for 3h, until constant mass, to make an ion – exchange column ready to adsorb thymol from aqueous solution. The surface area of 5 gm mass of adsorbent was calculated physically and it equals to (75.09cm 2). Adsorption Experiments A glass column (70 cm X 15 mm i.d.) filled with known mass (5gm) of adsorbent (modified organic Na – montmorillonite)corresponding to bed heights of 3cm, percolated with 5 ml of (5-50 mg/L) thymol solution adjusted to different pH values 2.5, 5.5 and 10.8 (optimum 5.5) by ~ 0.1 N NaOH or ~ 0.1 N HCl, and different contact time ( from 5 to 120 minutes) with flow rate (4.0drop/ mint).The equilibrium adsorption uptake (qe mg/g) and percentage removal of thymol from the aqueous solution was determined or calculated using the following relationship[19]. Amount adsorbed qe = ( C0-Ce )V/W (mg of adsorbate / g of adsorbent) % removal = 100( C0-Ce )/ Ce Where C0 is the initial sorbate concentration (mg/L), Ce the equilibrium sorbate concentration(mg/L), V is the volume of solution in L and w is the mass of the adsorbent in (g). Results and Discussion Characterization of clay Natural Iraqi bentonite FTIR spectrum[20] showed adsorption band at 3628.10 cm-1 (Al-Al-OH)(Mg-OH-Al) corresponding to streching vibration of structural OH groups coordinating to Al-Al pair or Mg-OH-Al fig.(1). Adsorbed water gives broad bands from 3406.29 cm -1 to 3533.59cm-1 corresponding to H2O- stretching vibration . Al, Mg bound water molecules gives H-O-H stretching vibration bond at 1643cm-1. Also three bands at 1546.91, 1427.32 and 1384.89 cm-1corresponding to H..O..H weak . The complex broad band around 1033 cm -1 belongs to Si-O stretching vibration . Two bands at 914.26 cm -1 and 837.11 cm -1 are most characteristic for quartz. Finally the bands from 420.00 cm-1to 516.93 cm-1 are related to Al-O-Si , Si-O-Si deformations. Initiated bentonite FTIR spectrum fig.(2) showed the same bands of fig.(1) but with higher transmittance percent and sharper than bands of FTIR spectrum of natural bentonite. Nevertheless H..O..H weak disappear in this spectrum. Adsorbed water band appear at 3421.72 cm -1,two bands belong to Al, Mg bound water molecules observed at 1654.92 cm-1 and 1641.42 cm-1 . The broad complex band becomes single band at 1039 cm -1 belongs to Si- O stretching vibration. Also we observe two bands belongs to Al…OH stretching vibration at 937.04 cm -1 and 916.19 cm-1 with higher transmittance percent .The quartz characteristics band from 694.37 cm -1 to 839.03 cm -1 become boarder. Finally Al-O-Si , Si-O-Si and Si-O stretching vibration bands from 426.27 cm -1 to 522.71 cm-1 become sharper and triplet bond[18] Hexadecyl trimethyl ammonium bromide modified Iraqi bentonite FTIR spectrum (Figure 3) showed two adsorption bands, the first at 2927.94 cm-1 corresponding to C – H of (- CH2) groups assymetric stretching vibration, and the second at 2854.65corresponding to C – H of (- CH3) groups stretching for tetrahedral carbon[18]. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Also we see an adsorption band at 1475.54 cm-1 corresponding to C – H bending of (- CH3) groups, and a band at 1456.26 cm-1 corresponding to C – H scissering in (- CH2) groups. C – N stretching adsorption band of quaternary aliphatic amine daesnt appear due to low force constant of this C – N bond of 4O aliphatic amine. The adsorption spectrum of thymol adsorbed on initiated modified Iraqi bentonite fig.(4), showed a band at 3545.16 cm -1 corresponding to O – H stretching free sharp band. Also two bands at 1643.35 cm-1 and 1475 cm-1 corresponding to C – C aromatic stretching. Another band appears at 1311.59 cm-1 corresponding to C – O stretching of thymol . Out of plane bending C – H bands appears at 939.33 cm-1. Absorption spectrum Fig.(5) shows the absorption spectrum of (25 mg/L) thymol against the reagent blank (distilled water), the maximum absorp tion wavelengths at 274nm. Calibration graph Employing the experimental conditions, linear calibration graph for thymol were obtained fig. (6), which show that Beer's law obey in the concentration range of (5-50 mg/L),The regression equations, correlation coefficients, molar absorptivities, and sandell sensitivities in addition to other parameters are given in table (2). Effect of time of adsorption(contact time) In order to establish the equilibrium time for adsoption, the effect of contact time was studied table (3) shows the results for the effect of contact time on the removal of thymol from aqueous solution at an initial concentration of 25 mg/l. about 52.040 %of thymol had been removed within the first fifteen minutes of adsorption and 67.876% within thirty minutes of adsorption. This is as a result, the adsorption capacity generally increases with the increase in contact time until reaches the equilibrium time of adsorption at 45 minutes with 77.072% had been removed. Effect of pH The pH of the thymol solution will effect on the ability of adsorption, increases the pH of (25mg/ L ) thymol solution from 2.5 to 5.5 leads to increase 3.5% of the % adsorbate removal, until when reaches to pH 10.8 leads to increase 4.1% of the % adsorbate removal, dissociation of thymol into (C10H13O –) will be repressed at pH > pKa[18]; (pKa value of thymol is10.59 ± 0.10) [21] , resulting in higher repulsion between the positive surface charge of the adsorbante and the anion. Effect of initial concentration The influences of thymol concentration on the adsorption activity are illustrated, This means that an increase in initial adsorbate concentration resulted in increasing of solute uptake fig.(7). The initial solute concentrations provide an important driving force to overcome all mass transfer resistance of adsorbate between aqueous and solid phase, the higher initial solute concentration will decrease the mass transfer resistance. Hence, higher initial concentration of adsorbate enhances adsorp tion process with the result of higher interaction between solute and the adsorbent[22,23]. Adsorption isotherm The equilibrium adsorption isotherm is important in the design of adsorption systems. Because it's useful to describe how solutes interact with adsorbents and very important to evaluate the feasibility of the adsorbate-adsorbent system. The set of experimental results as مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 presented in (Figure 8) at room temperature (25±0.1) was fitted with the Freundlich and Langmuir model. Adsorption isotherms were obtained and the adsorp tive capacity interpreted using both models. Freundlich isotherm The Freundlich expression [23] is an empirical equation describing sorp tion onto heterogeneous surface. The isotherm assumes that the surface sites of the adsorbent have a spectrum of different binding energies. The linear equation is presented as: log qe = log kF + 1/n log C0 where KF is The Freundlich constant (L/g) and 1/n is the adsorp tion intensity. The value of n indicates the favorable adsorption ability. , the values of log KF and 1/n can be calculated from the intercept and the slope of the linear plot of log qe versus log Ce fig.(9). Langmuir isotherm The Langmuir model [24] is widely used for modeling equilibrium data. The isotherm is valid for monolayer adsorption onto a surface containing a finite number of identical sites. It can be described by the linear form: 1/qe=1/qmax+1/qmaxKL ٠1/Ce where qmax is the adsorption capacity at saturation (mg/g) and KL (L/mg) is the adsorption coefficient related to energy of adsorption, the values of qmax and KL can be evaluated from the intercept and the slope of the linear plot of expermantal data of 1/qe versus 1/Ce fig.(10). The Langmuir isotherm can also be expressed by a separation factor [25], which is given by the equation . RL = 1/ (1 + KL٠ C0) Where, ‘C0’ is the initial concentration of thymol in mg/L and ‘KL’ is the Langmuir constant in g/L. The separation factor ‘RL’ indicates the nature of the adsorption process[26] as given in (Table 4). The results reveal that the adsorption of thymol was best fitting with Langmuir model rather than Freundlich table(5), as indicated by higher R 2 values, the low value of the Freunlich constant (kF = 0.001 L/g), which indicates the effectiveness of the thymol- Na – montmorillonite clay system and the value of adsorp tion intensity, ‘n’ is found to be 0.633 did not satisfy the condition of heterogeneity, i.e., 1< n < 10 as well as 0 < 1/n < 1 [27]. While the higher magnitude of ‘qmax’ (0.170 mg/g) for Langmuir mode indicates that the amount of thymol per unit weight of sorbent (to form a complete monolayer on the surface) seems to be significantly higher, also a relatively lower ‘KL’ value (0.018 L/mg) implies low surface energy (KL < 0.3), thus indicating a probable stronger bonding between thymol and sorbents [28]. Adsorption kinetics Kinetic models are used to examine the rate of the adsorption process in the present work, the kinetic data obtained from the studies have been analyzed by using pseudo-first-order and pseudo-second-order models. The pseudo first order equation of Lagergren is generally expressed as follows[29]. dq/dt=k1(qe-qt) مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 where qe is the amount of thymol adsorbed at equilibrium (mg/g), qt is the amount of thymol adsorbed at time t (min-1), and k1 is the rate constant of pseudo-first-order adsorption. If it supposed that q=0 at t=0, then: ln (qe-qt)= lnq- k1t The pseudo-second-order kinetic rate equation is expressed as follows [30]. dqt/dt=k2(qe-qt) 2 Where k 2 is the rate constant of pseudo-second-order sorption (g/mg/min). The integrated form of equation when (t=0 →t and qt=0→ 0qe) the following expression is obtained: t/qt=1/k2qe 2 + t/qe The rate constant k1, k2 and qe calculated from the slopes and intercepts of the linear plot of ln(qe-qt) or (t/qt ) against t respectively fig.(11and 12). It is seen that thymol removal well described by the psudo second order reaction kinetc. Moreover, the correlation coefficient (R 2), of pseudo-second-order reaction kinetic(0.991) is higher than that of the pseudo-first- order reaction kinetic(0.989) and greater value of rate constant for the adsorption data. While the value of qe experimental is approximately equal qe calculated for the both first and second order reaction kinetic; Table(6) shows the rate constants, qe (experimental , calculated ) and correlation coefficient (R 2 ) for psudo first and second order reaction kinetc. Analysis of Thymol The concentration of residual thymol (after adsorption) was determined spectrophotometrically according to the standard methods, at 274nm. Accuracy and precision The accuracies of the proposed methods were confirmed by analyzing three replicate analyses of four different amounts of thymol ;within Beer's law ( before and after adsorption) by calculating the relative error percentage. The results indicated good accuracies of the method. The precision was determined by calculating the percentage relative standard deviation (RSD %) for three determinations at each of the studied concentration level tables (7 and 8). Conclusion In this study, the adsorption of thymol from aqueous solution was investigated using granulated surfactant initiation modified bentonite. The results indicated that adsorption capacity of the adsorbent was considerably affected by contact time, initial pH, and initial thymol concentration. The results indicated that the uptake of thymol took place at a pH in the range of (2.5-10.8); the adsorption of thymol increased with increase of pH. The result also showed that the amount of thymol adsorbed increased the increase of initial thymo concentration. The results reveal that the adsorption of thymol obeys Langmuir adsorption isotherms. The pseudo-first and second-order kinetic models were used to analyze the data obtained for thymol adsorption from aqueous solution. The result indicated that the pseudo-second-order equation provided the better correlation coefficient (R 2 ) and the greater value of rate constant for the adsorption data. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 References 1. Nielson, A. H.; Allard, A. S.; Hynning, P. A. and Rememberger, M. (1991) Distribution, fate persistence of organochlorine compounds formed during production of bleached pulp, J. of Toxicol. Environ. Chem., 30: 3-41. 2. Cristina, M. S.; Zoraida, S. F.; Esther, M. T. P. and José, J. S. R. (2009) Review- Methodologies for the Extraction of Phenolic Compounds from Environmental Samples: New Approaches, J. of Molecules , 14: 298-320. 3. Chandra, S. M.; Krishna, K. S. and Vivek, K. G. 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(2006) Liquid chromatographic determination of phenol, thymol and carvacrol in honey using fluorimetric detection, J. of Talanta, 69: 1063–1067. 9. Nadja, B.W. ; Till, K. D. M. and Oliver, Z. (2005) determination of natural products using new methods of NMR spectroscopy, J. of Chemistry & Biodiversity, 2(2): 147- 177. 10. Jayant, K. V. and Anil, V. (2006) Rapid HPTLC method for identification and quantification of curcumin, piperine and thymol in an ayurvedic formulation, J. of Planar Chromatography, 19 (111): 398-400. 11. Zhao, H.T. and Vance, G.F.(1998) Sorption of trichloroethylene by organo-clays in the presence of humic substances, J. of Water Res. 32: 3710-3716. 12. Brindley,G.W. and Brown, G.(2010) Crystal Structures of Clay Minerals and their Xray Identification, Mineralogical Society , London, edited by IdentifierBot 31-July Last edited:1-495. 13. van Olphen, H.(1977)An Introduction to Clay Colloid Chemistry: For Clay Technologists, Geologies’, 2nd edition, Wiley Interscience, New York.316-318 14. Zadaka, D.; Mishael, Y.; Polubesova, T.; Serban, C. and Nir, S. (2007) Modified silicates and porous glass as adsorbent for removal of organic pollutants from water and comparison with activated carbons, J. of Applied Clay Science, 36 (1-3): 174– 181. 15. Abate, G. and Masini, J. C. (2005). Sorption of atrazine, propazine, deethylatrazine, deisopropylatrazine and hydroxylatrazine onto organovermiculite, J.of the Brazilian Chemical Society , 16 (5): 936–943. 16. Sandro, F.; Raquel, .F M .; Willian, F. and Marcelo, R. E.(2009)Water Remediation by Adsorption of Phenol onto Hydrophobic Modified Clay, J. of Water, Air, & Soil Pollution . 199 (1-4,):107-113.p مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 17. Hassan, M.S. ; Abdel-Khalek, N.A. (1998) Beneficiation and applications of an Egyptian bentonite, J. of Applied Clay Science 13(2): 99-115. 18. Uday, F. A.; Abduljabar, A. M. and Ammar, H. Al. (2009) The removal of phenol from aqueous solutions by adsorption using surfactant-modified bentonite and kaolinite, J. of Hazardous Materials, 169 (1-3): 324-332. 19. Zlem, C. and Demet, B. (2000) Adsorption of Some Textile Dyes by Hexa decyltrimethylammonium Bentonite, J. of Turk Chem, 25: 193-200. 20. Russell, J.D. and Fraser, A.R. (1994) Clay Mineralogy-Spectroscopic and chemical determinative methods (Wilson M.J. editor) Chapman and Hall, London. Chapter two(Infrared methods)11-67. 21. Budavari, S. (2001) “The Merck index”, New Jersy , Merck Company, Inc.. 22. Hawaiah, I. M.; Bassim, H. H. and Abdul Latif, A.(1996) adsorption equilibrium of phenols from aqueous Solution using modified clay, J. of jurutera Kimia Malaysia, 3:85 – 96. 23. Uddin, M. T.; Islam, M. S. and Abedin, M. Z. (2007) Adsorption of phenol from aqueous solutions by water hyacinth , J. of Engineering and Applied Sciences (ARPN). 2 (2):11-17. 24. Mahvi, A. H.; Maleki, A. and Eslami, A. (2004) Potential of Rice Husk and Rice Husk Ash for Phenol Removal in Aqueous Systems J. of American Applied Sciences, 1(4): 321-326. 25. Juang, R.S.; Wu, F.C.; Tseng, R.L.(1997) Ability of activated clay for the adsorption of dyes from aqueous solutions.J. of Environ. Technol. 18:525-535. 26. Srihari, V.; Das, A. (2009) Adsorption of phenol from aqueous media by an agro- waste (Hemidesmus indicus) based activated carbon. J. of Applied Ecology and Enviromental Research. 7(1): 13-23. 27. Khalid, N., Ahmad, S.and Toheed, (2000): A Potential of Rice Husk for Antimony Removal. J. of Applied Radiation and Isotopes 52:30-38. 28. Aksu, Z. and Yener, J. (2001)Acomparative adsorption/biosorption study of monochlorinated phenols onto various sorbent. – Waste management 21 (8): 695-702. 29. Lagergren, S. (1998) Zur theorie der sogenannten adsorp tion geloster stoffe, Kungliga Svenska Vetenkapsakademiens. J. of Handlingar, 24:1-13. 30. Ho, Y.S. and Mckay, G. (1999) Pseudo-second-order model for sorp tion process. J. of Process Biochem. 34 (5): 451-465. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Table (1): Chemical analysis West Iraqi (Traifawi) bentonite. Compound (wt, %) Iraqi (Traifawi) bentonite SiO2 55.81 Al2O3 14.91 Fe2O3 5.78 CaO 5.72 MgO 3.5 Na2O 1.29 K2O 0.41 LiO2 0.67 SO3 ---- L.I.O. 10.86 Total 98.95 Table (2): Spectral characteristics and statistical data of the regression equations for determination of thymol. Parameter Thymol λmax (nm) 274nm Color colorless Linearity range (mg/L) 5-50 Molar absorpitivites (l.mol-1.cm-1) 1922.816 Regression equation A = 0.0128 [ Thymol(mg/L)] + 0.0245 Calibration Sensitivity 0.0128 Sandell's Sensitivity (µg.cm -2 ) 78.125 Correlation of Linearity (R 2 ) 0.9983 Correlation coefficient (R) 0.9991 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Table (3): Effect of contact time on the adsorption of (25mgl/L) thymol from aqueous solution. Initial Conc. (mg/L) Time (minute) Equilibrium Conc. (Ce) (mg/L) % Removal qe (mg/g) Equilibrium Time (minute) 5 16.156 35.376 0.0088 10 13.798 44.808 0.0112 15 11.990 52.040 0.0130 20 10.426 58.296 0.0146 30 8.031 67.876 0.0169 40 6.379 74.484 0.0186 45 5.714 77.072 0.0193 60 5.714 77.072 0.0193 75 5.714 77.072 0.0193 90 5.714 77.072 0.0193 25.000 120 5.714 77.072 0.0193 45 Table(4): The process nature of separation factor. S .No. RL Value Type of process 1 RL > 1 Unfavorable 2 RL = 1 Linear 3 0 < RL < 1 Favorable 4 RL = 0 Irreversible Table(5): Freundlich and Langmuir isotherm parameters for the adsorption of thymol at (25±0.1) °C under optimum conditions. Freundlich isotherm parameters Langmuir isotherm parameters KF (L/g) n R 2 qmax (mg/g) KL (L/mg) R 2 RL * 0.001 0.633 0.988 0.170 0.018 0.990 0.526-0.917 * for (5-50 mg/L) initial concentration of thymol . مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Table(6): The pseudo- first and second- kinetic order parameters for the adsorption of 25 (mg/L) of thymol at (25±0.1) °C under optimum conditions. qe Expe. (mg/g) The pseudo-first-order kinetic models The pseudo-second-order kinetic models qe ca lc. (mg/g) K1 (min-1) R 2 qe ca lc. (mg/g) K2 (g/mg/min) R 2 0.0193 0.016 0.069 0.989 0.023 4.167 0.992 Table (7): Evaluation of accuracies and precisions for thymol before adsorption. *Average of three determinations. Table (8): Evaluation of accuracies and precisions for thymol after adsorption at optimum conditions. Concentration (mg/L) Taken Found(Co)* After Adsoption % Removal Relative Error* % R.S.D.* % 10 3.014 69.860 1.427 1.701 25 5.714 77.144 1.383 1.663 40 8.471 78.822 1.522 1.874 50 9.964 80.072 2.721 2.987 *Average of three determinations. Concentration ((mg/L) Taken Found* Before Adsoption Relative Error* % R.S.D.* % 10 9.897 1.030 1.212 25 24.775 0.900 1.158 40 39.572 1.070 1.371 50 48.878 2.244 2.816 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig. (1): FTIR spectrum for crude Iraqi bentonite (Trifawi). Fig. (2): FTIR spectrum for initiated Iraqi bentonite (Trifawi). Fig. (3): FTIR spectrum for initiated modified Iraqi bentonite (Trifawi). مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig. (4): FTIR spectrum for thymol adsorbed on initiated modified Iraqi bentonite. Fig. (5): Absorption spectrum of (25mg/L) thymol, against reagent blank (distal water). مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig. (6): Calibration curve for thymol Fig.(7): Effect of initial against reagent blank(distilled water) concentration onto adsorption at 274nm. of (10, 25 and40)mg/L of thymol solution Fig.(8):Adsorption isotherm for Fig.(9):Freundlich isotherm for thymol at(25±0.1) °C under the adsorption of thymol optimum conditions. at(25±0.1) ° C under optimum conditions. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(10): Langmuir isotherm for the Fig.(11): The pseudo -first- orde kinetic a dsorption of thymol at(25±0.1) °C models for the adsorption of under optimum conditions. 25(mg/L)thymol at(25±2) °C under optimum conditions. Fig.(12): The pseudo-second-order kinetic models for the adsorption of 25 (mg/L) of thymol at (25±0.1) ° C under optimum conditions. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 امتزازالثایمول من محلوله المائي بأستعمال طین البنتونایت المنشط والمحورعضویآ بطریقة العمود المعبأ محمد حسن عبد اللطیف، علي خلیل محمود ، مھا عبد الحمید العبایجي قسم الكیمیاء، كلیة التربیة ابن الھیثم، جامعة بغداد 2011 تشرین األول 18: قبل البحث في 2011 حزیران 16: استلم البحث في الخالصة طین البنتونایت العراقي المنشط المعغرفة، بأست اجریت دراسة ألمتزاز الثایمول من محلوله المائي بدرجة حرارة ال شخص البنتونایت المنشط . ت طریقة العمود في عملیة االمتزازلمع استاذ المونتموریلونایت والمحور عضویآ، أةعلى هی كما تم الحصول على منحني تدریجي خطي ه وبعد والمحور بأستخدام طیف االشعة تحت الحمراء، قبل امتزاز الثایمول وعند الطول الموجي ، لتر/ ملي غرام) 50-5(لول الثایمول وبمطاوعة لقانون المبرت بیر لمدى من التراكیز یتراوح بینلمح ة الزم لحصول وجد ان الزمن ااذ المتغیرات المؤثرة في عملیة االمتزاز، تدرس. نانو متر، ضد محلول الخلب274 ل عملی دالة الحامضیة حظولو. قطرات لكل دقیقة4 دقیقة، وبسرعة جریان 45االتزان هو pH)( زیادة في امتزاز المحلول بزیادة ال ا فيشكل فیزیائي وكما وجد ان طبیعةعملیة االمتزاز ذ. اوبزیادة التركیز االبتدائي للمادة الممتزة، االغلب، وینطبق علیه . وأظهرت النتائج ان عملیة األمتزاز تتبع تمامآ حركیة المرتبة الثانیة الكاذبة. زایزوثیرم النكمایر لالمزا مونتموریلونایت، طین، طریقةالعمود - امتزاز، ثایمول، صودیوم :الكلمات المفتاحیة مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012