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Sorptive Removal of Dyes Using Titanium Phosphate Kalpana C. Maheria and Uma V. Chudasama* Applied Chemistry Department, Faculty of Technology & Engineering, The M.S. UniVersity of Baroda, Vadodara-390001, Gujarat, India
Basic dyes have been found to be the most soluble dyes used in textile industries that, with their tinctorial values being high and even in small quantities, produce obvious coloration. Adsorption has often been used as a method to remove dissolved contaminated organic compounds because of simplicity of design, ease of operation, and insensitivity to toxic substances. When a cation-exchange material is used as a sorbent, it is believed that the interaction of the functional groups present in the dye with the matrix material (sorbent) being used could be anywhere from covalent to Coulombic, hydrogen bonding, or weak van der Waals forces. In the present study, titanium phosphate (TiP), an inorganic ion-exchange material of the class of tetravalent metal acid salt has been synthesized by sol-gel method, characterized, and used as a sorbent. The sorption behavior of cationic dyes Crystal Violet (CV), Rhodamine 6G (R6G), Methylene Blue (MB), and Pink FG (PFG) toward TiP has been studied, based on thermodynamic parameters evaluated and adsorption isotherms (Langmuir and Fruendlich). Breakthrough capacity and elution behavior of dyes have also been studied. Sorption affinity of dyes toward TiP is found to be MB > CV> R6G > PFG. 1. Introduction Dyes are highly dispersible aesthetic pollutants that contribute to aquatic toxicity. It has been reported that dye wastewater is poisonous, carcinogenic, and teratogenic to human beings.1 Wastewater is the principle route by which dyestuffs enter the environment. A large variety of dyestuffs such as acid, basic, reactive, and direct dyes can be found in effluents out of which basic dyes have been found to be the most soluble dyes that, with their tinctorial values being high and even in small quantities, produce obvious coloration.2 It thus becomes essential to design a cost-effective color-removal process that has attracted wide attention.3 Literature4-6 is available on the problem of color search for solutions and currently available technologies. The various treatment methods for the removal of color/dyes are adsorption,7-9 coagulation,5,10 chemical oxidation (using chlorine and ozone),11,12 membrane filtration,13 ion-exchange14,15 chemical reduction, and biological treatment.16,17 Factors affecting the technical and economic feasibility of each technique are wastewater composition, operation costs, dye type, and generated waste products. The coagulation process effectively decolorizes insoluble dyes but does not work well for soluble dyes. There is also a large volume of sludge formation. Oxidation processes such as ozonation decolorize almost all dyes except disperse dyes but do not remove chemical oxygen demand (COD) well. The biological process does not effectively decolorize commercial dyes. Therefore, the use of one individual technique is not sufficient to achieve complete decolorization. Therefore, dye-removal strategies consist of a combination of different techniques.18 Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorptives are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Adsorption has often been used as a method to remove dissolved contaminated organic compounds16 because of simplicity of design, ease of operation, and insensitivity to toxic substances. Ion exchange * To whom correspondence should be addressed. Tel.: (0265) 2434188 (O). Cell No.: 9426344434. Fax: (0265) 2423898. E-mail:
[email protected].
is also a highly effective method for eliminating dissolved contaminants such as colorants and toxic metal ions. It has been observed that ion-exchange systems have been ignored as a viable technology for treatment of dye effluents, probably because of the fact that ion exchangers cannot accommodate the wide diversity of dyes; the dye bath conditions, due to the poor performance; or the presence of other additives in the wastewater stream.19,20 However, there are a few publications where ion-exchange materials have been used as sorbents for the removal of dyes.15,19,21-23 A large number of suitable sorbents such as activated carbon, coal, clays, zeolites, peat, lignite, corn cobs, fly ash, bagasse fly ash, recycled alum sludge, perlite, agriculture waste residues, and so on have been studied.24,25 McKay and co-workers26-29 have carried out extensive work on adsorption of a variety of dyes using natural sorbents such as bentonite, bagasse pith, coal, etc. Allen et al.30 have studied basic dyes adsorption by Kudzu. The use of novel alternative sorbent materials continues to attract attention because of economic considerations, availability, and adsorption efficiency. In particular, there is a need for more research into tailoring the manufacture of specific adsorbents for particular applications together with more general adsorbents with wider applications. Among the various ion exchangers used, synthetic ion exchangers of the class of tetravalent metal acid (tma) salts have been receiving increasing attention31-33 because of their stability toward heat, ionizing radiation, and selectivity toward several metal ions. These materials possess the general formula M(IV) (HXO4)2‚nH2O, where M(IV) ) Zr, Ti, Th, Ce, Sn, etc. and X ) P, Mo, As, W, Sb, etc. The presence of structural hydroxyl protons is responsible for the ion-exchange behavior. Dyes, in general, contain one or more of the following functional groups in their structure (-OH, -COOH, -SO3H, -NO2, -NH2, s NdNs, etc.). It is believed that, in ion exchange, the interaction of the above functional groups with the matrix material (ion exchanger) being used could be anywhere from covalent to Coulombic, hydrogen bonding, or weak van der Waals forces. The ability of the dye to be eluted out depends on the strength and type of interaction. It was thought of interest to use tma salts for wastewater treatment containing dyes. Because of the
10.1021/ie061520r CCC: $37.00 © 2007 American Chemical Society Published on Web 09/12/2007
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Figure 1. Structure of dyes.
presence of the structural hydroxyl groups, it is expected that the dye could either be bound by hydrogen bonds or by the weak van der Waals forces. Though the cation-exchange characteristics of tma salts are well-established, not much work has been reported on the adsorption characteristics of these materials. The present study involves the synthesis of amorphous titanium phosphate (TiP), of the class of tma salt by sol-gel method. TiP has been characterized for elemental analysis (ICPAES), thermal analysis (TGA and DSC), spectral analysis (FTIR), and X-ray diffraction. Because of the presence of structural hydroxyl groups in TiP, it is expected that the dye could either be bound to the matrix material (TiP) by hydrogen bonds or by the weak van der Waals forces, making sorption and desorption easy and possible. It was, therefore, thought of interest to use TiP as a sorbent for wastewater treatment containing dyes. The sorption behavior of cationic dyes, namely, Methylene Blue (MB), Crystal Violet (CV), Rhodamine 6G (R6G), and Pink FG (PFG) (Figure 1), toward TiP has been studied, based on thermodynamic parameters evaluated and adsorption isotherms (Langmuir and Fruendlich). Breakthrough capacity and elution behavior of dyes have also been studied and discussed. 2. Materials and Methods Titanium tetrachloride was procured from Spectrochem Pvt. Ltd., and sodium dihydrogen phosphate was procured from E. Merck Ltd. (India). Dyes CV, RG, and MB were supplied by S.D. Fine chem. Ltd., whereas PFG was procured from Colortex Ltd. (India). All reagents (H2SO4, HNO3, HCl, KCl, etc.) used were of analytical grade. 2.1. Synthesis of TiP. TiP has been prepared by dropwise addition of aqueous solution of sodium dihydrogen phosphate (0.1 M, 50 mL) and titanium tetrachloride (0.1 M, 50 mL, prepared in 20% HCl), with continuous stirring and maintaining temperature of the solution at 343 K. On complete precipitation, the gel obtained was stirred for a further 5 h. It was then kept in contact with the mother liquor overnight for aging. It was further stirred for 1 h at 343 K, filtered hot, and washed with hot conductivity water till the complete removal of chloride ions, followed by drying at room temperature. The material was then broken down to the desired particle size [30-60 mesh (ASTM)] by grinding and sieving. The material was converted to the acid form by taking 5 g of the material and treating it with 50 mL
of 1 M HNO3 for 30 min with occasional shaking. The sample was then separated from acid by decantation and washed with conductivity water for removal of the adhering acid. This process was repeated at least five times. After final washing, the material was dried at room temperature. The Na+ ion-exchange capacity (IEC) of the material was determined by the column method.34 This material was used for all studies. 2.2. Calcination Studies. The effect of heating on IEC was studied by heating a 1 g portion of the material TiP for 2 h at temperatures between 373 and 773 K with 100 K intervals in a muffle furnace and determining the Na+ IEC by the column method34 at room temperature. 2.3. Chemical Resistivity. The chemical resistivity of the material in various mediasacids (H2SO4, HNO3, and HCl), bases (NaOH and KOH), and organic solvents (ethanol, benzene, and acetone)swas studied by taking 500 mg of sample in 50 mL of the particular medium and allowing it to stand for 24 h. The change in nature, weight, and color was observed. 2.4. Instrumentation. TiP has been analyzed for titanium and phosphorus by ICP-AES. The FTIR spectrum of TiP was obtained using KBr powder on Shimadzu (model 8400S). Thermogravimetric analysis of TiP was performed on a SII Seiko (model TG/DTA-32) thermal analyzer at a heating rate of 20 K‚min-1. Differential scanning calorimetric analysis was carried out using Shimadzu (model DSC-50) system at a heating rate of 10 K‚min-1. The X-ray diffractogram was obtained on an X-ray diffractometer (model Brucker AXS D8) using Cu KR radiation source with a nickel filter. A temperaturecontrolled shaker bath having a temperature variation of (0.5 K was used for thermodynamic studies. Dye adsorption/ desorption was determined using visible spectrophotometer. 2.5. Sorption Experiments. 2.5.1. Effect of pH. Effect of pH on sorption was studied by taking 1 g of TiP and transferring it into a glass column (diameter ) 1.2 cm and length ) 20 cm). Feed solution (5 mL) containing 100 mg‚L-1 of each dye under study was allowed to pass through the column, varying pH in the range of 2-10 with increments of 2 and maintaining a flow rate of 0.1 mL‚min-1. pH was adjusted in the acidic range using dilute HNO3 and in the alkaline range using dilute NaOH. Dye concentration was determined spectrophotometrically using the calibration curve of the individual dye. 2.5.2. Adsorption Isotherms. Adsorption isotherms were studied by taking 20 mL of each dye solution of varied concentrations [10, 20, 30, 40, and 50 mg‚L-1] and shaking it
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Figure 2. FTIR spectra of TiP.
water, was prepared. Synthetic effluent (50 mL) was shaken with 500 mg of TiP in stoppered conical flasks at constant temperature (303 K) at different time intervals with increments of 15 min (15, 30, 45, 60, and 75 min). The supernatant liquid was removed immediately, and the COD was measured each time to determine the extent of dye removal. 3. Results and Discussion
Figure 3. TG/DTA plot of TiP.
with 200 mg of TiP [30-60 mesh (ASTM)] for 90 min in stoppered conical flasks at 313 and 323 K. The pH of the solution was adjusted to the value at which the maximum sorption of the respective dye took place. The supernatant liquid was removed immediately after the requisite time, and the dye concentration was evaluated spectrophotometrically. Results obtained from this study were utilized to evaluate thermodynamic parameters (∆H°, ∆G°, and ∆S°) using the equations discussed in the Results and Discussion section. 2.5.3. Breakthrough Capacity. Breakthrough capacity was determined by taking 5 mL of feed solution containing dye (100 mg‚L-1 in the case of CV, R6G, and PFG and 5000 mg‚L-1 in the case of MB) and passing it through the column containing 1 g of TiP, maintaining a flow rate of 0.1 mL‚min-1. The process was continued until the amount of dyes was the same in the feed and the effluent. Breakthrough capacity was calculated using the ratio Ce/Co, where Ce is the concentration of the dye in the effluent and Co is the concentration of dye in the feed.35 2.5.4. Elution Behavior of Adsorbed Dyes. Elution behaviors were studied by taking 5 mL of each dye solution (containing 100 mg‚L-1 of CV, R6G, and PFG and 500 mg‚L-1 of MB) and passing them through the column containing 1 g of TiP, maintaining a flow rate 0.1 mL‚min-1. It was then eluted with reagents like HCl, HNO3, H2SO4, and KCl of 0.01 M concentration. The amount of dye recovered was calculated as (Ce/Co) × 100, where Ce ) concentration of dye in eluted solution and Co ) initial concentration of dye. The amount of dye adsorbed or eluted was determined spectrophotometrically in all cases. 2.5.5. Case Study. In order to explore the utility of TiP in wastewater treatment containing dyes, a synthetic effluent containing MB, having similar composition to textile waste-
3.1. Characterization of TiP. Titanium phosphate is obtained as white granules. Elemental analysis by ICP-AES shows the titanium-to-phosphorus ratio to be 1:1. The FTIR spectra of TiP (Figure 2) shows a broad band in the region ∼3400 cm-1 attributed to symmetric and asymmetric -OH stretching, while a band at ∼1614 cm-1 is attributed to HsOsH bending. A band in the region ∼975.91 cm-1 is attributed to PdO stretching. This indicates the presence of structural hydroxyl groups in TiP, with the H of the OH groups being the cationexchange site. This fact is more evident from the IEC values that have been evaluated. The Na+ IEC, determined by the column method,34 is found to be 3.09 meq‚g-1. The IEC of the samples calcined at temperatures between 373 and 773 K with 100 K intervals is found to be 3.60, 3.40, 1.99, 1.33, and 1.02 meq‚g-1, respectively. The initial increase in the IEC value at 373 K could be attributed to the loss of moisture adhered to it, thereby increasing the active exchanger content for the same weight of material taken for IEC determination. The decrease in IEC beyond 573 K could be attributed to the condensation of structural hydroxyl groups. The theromogram of TiP (Figure 3) exhibits two regions of weight loss. The first weight loss within the temperature range 303-427 K is attributed to the loss of moisture/hydrated water, while the second weight loss observed in the range 427-766 K is attributed to the condensation of structural hydroxyl groups. The differential scanning calorimetric curve of TiP (Figure 4) exhibits an endothermic peak at ∼408 K, which is attributed to the loss of moisture/hydrated water. However, beyond this temperature, no peaks are observed, indicating the absence of any phase change in the material upon thermal treatment. The absence of sharp peaks in the X-ray diffratogram of TiP (Figure 5) indicates the amorphous nature of the material. On the basis of the titanium and phosphorus content determined by (ICP-AES) and thermal analysis (TGA) data, TiP has been formulated as TiO(OH)(H2PO4)‚H2O using the Alberti Torracca formula.36 TiP is found to be stable in an acid medium, with the maximum tolerable limits being 18 N H2SO4, 16 N HNO3, and 11.3 N HCl, and also stable in organic solvent media
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Figure 6. Freundlich adsorption isotherms for MB.
Figure 4. DSC curve of TiP.
Figure 7. Langmuir adsorption isotherms for MB. Table 3. Thermodynamic Parameters for Sorption of Dyes dye CV R6G MB PFG Figure 5. X-ray profile of TiP. Table 1. Effect of pH on the Sorption of Dyes percentage adsorbed dye (Co ) 100 mg‚L-1) pH ) 2 pH ) 4 pH ) 6 pH ) 8 pH ) 10 CV R6G MB PFG
98.02 83.02 94.72 90.53
97.80 84.59 96.94 82.72
98.20 86.54 99.09 83.71
96.19 81.22 93.96 81.20
92.90 78.46 90.20 100.0
Table 2. Langmuir and Freundlich Constants for Sorption of Dyes Langmuir constants dye CV R6G MB PFG
Freundlich constants
temp (K)
θ° (mg‚g-1)
b (L‚mg-1)
R2
k
1/n
R2
313 323 313 323 313 323 313 323
54.94 29.67 217.39 33.11 196.08 128.21 142.85 25.06
0.057 0.029 0.004 0.010 0.027 0.010 0.010 0.036
0.9551 0.7921 0.9969 0.9913 0.9886 0.9299 0.9710 0.9050
7.39 1.17 1.26 8.60 0.03 3.18 2.09 1.96
0.425 0.874 0.449 0.541 1.514 0.420 0.802 0.515
0.9845 0.8986 0.9869 0.9820 0.9708 0.9594 0.8988 0.9993
(ethanol, benzene, and acetone) but not so stable in a base medium, with the maximum tolerable limits being 5 N NaOH and 0.5 N KOH. 3.2. Sorption Studies. It is observed from Table 1 that maximum adsorption takes place at pH 6 in the cases of CV, MB, and R6G and at pH 10 for PFG. For all other studies, the pH was adjusted to 6 and 10, respectively. Generally, both Langmuir and Freundlich isotherms are used for explaining the adsorption on materials. Standard equations37 have been used to find values of various constants of both
temperature (K)
∆H° (kJ‚mol-1)
∆G° (kJ‚mol-1)
∆S° (kJ‚mol-1‚K-1)
313 323 313 323 313 323 313 323
-56.794
-0.521 -9.042 -9.530 -6.280 -8.577 -12.452 -5.939 -9.615
-0.1478 -0.1478 -0.2300 -0.2350 -0.3870 -0.3876 -0.3290 -0.3080
-82.192 -112.75 -109.10
isotherms. Values of their constants and correlation coefficients (R2) have been summarized in Table 2. It is observed that the values of R2 are very close to unity for both isotherms, indicating applicability of both isotherm models. As a representative, Freundlich and Langmuir isotherms for MB have been given in Figures 6 and 7, respectively. It is observed from Table 2 that the values of θ0 (maximum adsorption capacity) decrease with the rise in temperature, indicating the exothermic nature of the adsorption process,38 whereas R2 varies with temperature, which is attributed to the fact that the surface adsorption is not a monolayer with a single site. Two or more sites with different affinities may be involved in dye sorption.39 In order to explain the effect of temperature on the sorption, thermodynamic parameters, standard free energy ∆G°, standard enthalpy ∆H°, and standard entropy ∆S°, were determined using the standard equations37 and are presented in Table 3. Negative ∆G° values indicate high affinity of dyes toward TiP and that the adsorption process is spontaneous. Negative ∆H° values indicate that sorption of dyes is exothermic in nature. This is also supported by the decrease in θ° values with the increase in temperature. The negative ∆S° values in all cases indicate the absence of disorderliness in the system. A decrease in ∆S° values indicates higher uptake of the dyes, which is a result of the high S° in the external aqueous phase and a lower S° in the sorbent phase.40 The breakthrough capacity depends on the flow rate of the feed solution through the column, the bed depth, the selectivity coefficient, the particle size, and the temperature. Breakthrough
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Good sorption as well as elution of dyes using TiP indicates its promising use in wastewater treatment containing dyes. Literature Cited
Figure 8. Breakthrough curves for CV, MB, R6G, and PFG. Table 4. Elution of Dyes Using Acids and Electrolytes as Eluantsa CV
R6G
MB
PFG
eluting agent
Ev
%E
Ev
%E
Ev
%E
Ev
%E
0.01 M HNO3 0.01 M HCl 0.01 M H2SO4 0.01 M KCl
25 40 40 40
95.40 82.80 81.00 31.00
35 40 40 40
95.10 81.00 93.00 82.10
40 40 40 35
99.30 84.00 91.90 50.00
60 65 55 55
100.0 94.00 58.00 100.0
a
Ev ) mL of eluting agent, and % E ) percentage elution.
curves (plots of Ce/Co vs effluent volume) for the sorption of the dyes, CV, R6G, MB, and PFG, on TiP are presented in Figure 8. It is observed that breakthrough capacity follows the order MB > CV > R6G > PFG being sorbed on the cation exchanger, which could be attributed to the cationic nature of dyes. Probably even small changes in the dye structure may significantly influence the adsorption capacity. The very high value observed in the case of MB could be due to the positive charge at the heteroatom. Though there is a positive charge in the cases of CV and PFG, the breakthrough capacity is less, which may be attributed to phenyl rings causing steric effects. In the case of R6G, lower values may be due to both steric effects as well as the nonionic nature of R6G. The percentage elution of dyes sorbed on TiP (Table 4) ranges between 80-100%, indicating acids and electrolyte to be good eluting agents. From Table 4, it is observed that acids, in general, are better eluants than electrolytes. However, 0.01 M HNO3 is the best eluant for all dyes. In the case of PFG, there is 100% elution using 0.01 M HNO3 as well as 0.01 M KCl. Because of the presence of structural hydroxyl groups in TiP, the dyes are probably bound by hydrogen bonds or the weak van der Waals forces, making sorption and elution easy and possible. In the present study, the maximum sorption capacity of MB toward TiP is 196.08 mg‚g-1. Similar studies carried out on activated carbon made from guava seeds showed that the sorption toward MB41 is 0.667 mg‚g-1. Though activated carbon obtained from guava seeds is a low-cost material, TiP is more effective toward removal of dyes, probably because of its cation-exchange property. A case study using a synthetic effluent containing MB shows that COD reduction at different time intervals is 83.01% (15 min), 90.12% (30 min), 96.45% (45 min), 97.23% (60 min), and 98.65% (75 min), indicating good efficiency of TiP toward removal of MB from textile wastewater. Conclusions Titanium phosphate, an inorganic ion-exchange material, exhibits good chemical resistivity and thermal stability, which are characteristics of a good sorbent. Thermodynamics of sorption as well as adsorption isotherms indicate good sorption behavior. Breakthrough capacity indicates good affinity of dyes toward TiP, found to be in the order MB > CV > R6G > PFG.
(1) Azim, W.; Sani, R. K.; Banerjee, U. C. Biodegradation of triphenylmethane dyes. Enzyme Microb. Technol. 1998, 22, 185-191. (2) Mohan, D.; Singh, K. P.; Singh, G.; Kundan, K. Removal of dyes from wastewater using flyash, a low-cost adsorbent. Ind. Eng. Chem. Res. 2002, 41 (15), 3688-3695. (3) Walker, G.; Weatherley, L. Biodegradation and biosorption of acid anthraquinone dye. EnViron. Pollut. 2000, 108 (2), 219-223. (4) Reife, A.; Freeman, H. S. EnVironmental Chemistry of Dyes and Pigments; Wiley: New York, 1996. (5) Cooper, P. Colour in dye house effluent; Society of Dyers & Colorists: Bradford, U.K., 1995; ISBN-0 901956 69 4. (6) Yeh, Y.-L.; Thomas, A. Colour difference measurement and colour removal from dye wastewaters using different adsorbents. J. Chem. Technol. Biotechnol. 1995, 63 (1), 55-59. (7) Cooper, P. Removing colour from dye house wastewater. Asian Text. J. 1995, 3 (4), 52-56. (8) Vandevivere, P.; Bianchi, C.; Verstaete, R. W. Treatment and reuse of wastewater from the textile wet processing industry: Review of emerging technologies. J. Chem. Technol. Biotechnol. 1998, 72 (4), 289-302. (9) Smith, K. T.; Brent, H. S. Decolorizing dye wastewater using chitosan. Am. Dyest. Rep. 1993, 82, 18-36. (10) Klimiuk, E.; Filipkowska, U.; Libecki, B. Coagulation of wastewater containing reactive dyes with the use of polyaluminium chloride (PAC). Polish J. EnViron. Stud. 1999, 8 (2), 81-88. (11) Arslan-Alaton, Ik.; Kornmuller, A.; Jekel, M. R. Contributions of free radicals to ozonation of spent reactive dye baths bearing aminofluorotriazine dyes. Color. Technol. 2002, 118 (4), 185-190. (12) Hasan, M. M.; Hawkyard, C. J. Reuse of spent dye bath following decolorization with ozone. Colour Technol. 2003, 118 (3), 104-111. (13) Albanis, T. A.; Hela, D. G.; Sakellarides, T. M.; Danis, T. G. Removal of dyes from aqueous solutions by adsorption on mixtures of fly ash and soil in batch and column techniques. Global Nest.: Int. J. 2000, 2, 237-244. (14) Annadurai, G.; Juang, R. S.; Lee, D. J. Use of cellulose based wastes for dyes. J. Hazard Mater. 2002, 92, 263. (15) Jorgenson, S. E. Examination of the applicability of cellulose ion exchangers for water and wastewater treatment. Water Res. 1979, 13, 12391247. (16) Safarik, I.; Safarikova, M.; Buricova, V. Sorption of waste soluble organic dyes on magnetic Poly(Oxy-2,6-Dimethyl-1,4-Phenylene). Collect. Czech. Chem. Commun. 1995, 60, 1448-1456. (17) Pagga, U. M.; Taeger, K. Development of a method for adsorption of dyestuffs on activated sludge. Water Res. 1994, 28, 1051-1057. (18) Kuo, W. G. Decolorizing dye waste water with Fenton’s reagent. Water Res. 1992, 26 (2), 881-886. (19) Laszlo, J. A. Electrolyte Effects on hydrolyzed reactive dye binding to quaternized cellulose. Text. Chem. Color. 1995, 27 (4), 25-27. (20) Reife, A. Dyes, Environmental Chemistry. In Encyclopedia of Chemical Technology, Vol. 8, fourth ed.; Howe, G., Ed.; Wiley: New York, 1993; p 753. (21) Laszlo, J. A. Removing acid dyes from textile wastewater using biomass for decolourization. Am. Dyest. Rep. 1994, 83 (8), 17-21. (22) Laszlo, J. A. Preparing an ion exchange resin from sugarcane bagasse to remove reactive dye from wastewater. Text. Chem. Color. 1996, 28 (5), 13-17. (23) Skelly, K. Water Recycling. ReV. Prog. Color. 2000, 30, 21-34. (24) Gupta, V. K.; Suhas, L. Ai.; Mohan, D. Equilibrium uptake and sorption dynamics for the removal of basic dye (basic red) using low cost adsorbents. J. Colloid Interface Sci. 2003, 265, 257-264. (25) Ho, Y. S.; Chiang, C. C.; Hsu, Y. C. Sorption Kinetics for Dye removal from aqueous solution using activated clay. Sep. Sci. Technol. 2001, 36, 2473-2488. (26) McKay, G.; Geundi, M. E.; Nassar, M. M. Equilibrium studies during the removal of dyestuffs from aqueous solutions using bagasse pith. Water Res. 1987, 21 (12), 1513-1520. (27) McKay, G. Equilibrium studies for the adsorption of dyestuffs from aqueous solutions by low-cost materials. Water, Air, Soil Pollut. 1986, 29, 273-283. (28) Poots, V. J. P.; Mckay, G.; Healy, J. J. The removal of acid dye from effluent using natural adsorbents. II: Wood. Water Res. 1976, 10, 1067-1070.
Ind. Eng. Chem. Res., Vol. 46, No. 21, 2007 6857 (29) Choy, K. K. H.; McKay, G.; Porter, J. F. Sorption of acid dyes from effluents using activated carbon. Resour. ConserV. Recycl. 1999, 27, 57-71. (30) Allen, S. J.; Gan, Q.; Matthews, R.; Johnson, P. A. Comparison of Optimized Isotherm Models for Basic Dye Adsorption by Kudzu. Bioresour. Technol. 2003, 88, 143-152. (31) Takahashi, H., Oi, T.; Hosoe, M. Characterization of semi crystalline titanium (IV) Phosphates and their selectivity of cations and lithium isotopes. J. Mater. Chem. 2002, 12, 2513-2518. (32) Clearfield, A. Inorganic Ion Exchange Materials; CRC Press, Inc.: Boca Raton, FL, 1982. (33) Qureshi, M.; Varshney, K. G. Inorganic ion exchangers in chemical analysis; CRC Press, Inc.: Boca Raton, FL, 1991; p 177. (34) Samuelson, O. Ion Exchangers in Analytical Chemistry; Wiley: New York, 1953; pp 45 and 117. (35) Benefield, L. D.; Judkins J. F.; Weand, B. L. Process Chemistry for water and wastewater treatment; Prentice Hall Inc.: Englewood Cliffs, NJ, 1982. (36) Alberti, G.; Torracca, E. Crystalline insoluble acid salts of polyvalent metals and polybasic acids. VI. Preparation and ion exchange properties of crystalline titanium arsenate. J. Inorg. Nucl. Chem. 1968, 30, 3075-3080.
(37) Singh, D. K. Basic dyes removal from wastewater by adsorption on rice husk carbon. Indian. J. Chem. Technol. 2001, 8, 133-139. (38) Jain, K.; Gupta, V.; Bhatnagar, K.; Jain, A.; Suhas, S. Comparative assessment of adsorbents prepared from industrial wastes for the removal of cationic dye. J. Indian Chem. Soc. 2003, 80, 267-270. (39) Horsfall, M.; Ayebaemi, J.; Spiff, I. Effects of temperature on the sorption of Pb(II) and Cd(II) from aqueous solution by caladium bicolor (wild cocoyam) biomass. Electron. J. Biotechnol. 2005, 8 (2), 162169. (40) Qureshi, M.; Rawat, J. P. Ion exchange studies in niobium arsenate. J. Indian Chem. Soc. 1981, LVIII, 855-858. (41) Rahman, I. A.; Saad, B. Utilization of guava seeds as a sources of activated carbon for removal of methylene blue from aqueous solutions. Malaysian J. Chem. 2003, 5 (1), 008-019.
ReceiVed for reView November 28, 2006 ReVised manuscript receiVed May 3, 2007 Accepted July 29, 2007 IE061520R
