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  1. 1. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 77 Research Paper ADSORPTION ISOTHERM STUDIES OF Hg(II), Pb(II), and Cd(II) IONS REMOVAL FROM AQUEOUS SOLUTIONS USING UNMODIFIED AND ESTER MODIFIED (ESTERIFIED) SENILIA SENILUS AND THAIS CORONATA BIOMASS OSU CHARLES I.1* and S.A. ODOEMELAM2 1Department of Pure and industrial chemistry, University of Port Harcourt, PMB, 5323, Port Harcourt, Rivers State. Nigeria. 2 *Corresponding Author: Phone: +2348037783246; Email: charsike@yahoo.com Department of Chemistry, Michael Okpara University of Agriculture, Umudike, Nigeria. Received: 7rd February 2012; Revised: 3rd June 2012; Accepted: 3rd June 2012 Abstract: Removal of heavy metal from aqueous solutions using developed alternative treatment methodologies was investigated. Senilia senilus (anadara) and Thais coronata (grastropoda) biomass were found to be a better adsorbent for the removal of Hg2+, Pb2+, and Cd2+ .This method of heavy metals removal proved highly effective as removal efficiency increased as the initial concentration increased. The removal was high for Hg2+ ranging from 98.00 – 99.97 %. Also, the ester modification did not enhance the adsorption capacity. Among three adsorption isotherm tested, Freundlich adsorption isotherm gave the best fit with r2 value ranging from 0.9887 to 1.0000 and average value of 0.9998. The biomass and method used were efficient and cost effective, and have successfully used for the removal of Hg2+and Cd2+ ions from aqueous solution. Keywords: Adsorption isotherm, biomass, heavy metal ions INTRODUCTION Heavy metals pollution increases with the advancement in industrialization and urbanization. The release of these heavy metals poses a significant threat to the ecosystem and public health because of their toxicity [1, 2]. Heavy metals are not biodegradeable. When they accumulate in the environment and in food chains, they can profoundly disrupt biological processes. Anthropogenic activities such as agriculture, electroplating, metal finishing industries, metallurgical industries, tannery, fertilizer industries etc increase the level of heavy metals in the This work is licensed under the Creative Commons Attribution 3.0 Unported License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ISSN 2088-3218 V o l u m e 2 , N u m b e r 2 : 7 7 - 8 6 , A u g u s t , 2 0 1 2 © T2012 Department of Environmental Engineering Sepuluh Nop em ber Institute of Technolog y, Suraba ya & Indonesian Society of Sanitary and Environmental Engineers, Jakarta O p e n A c c e s s h t t p : / / w w w . t r i s a n i t a . o r g / j a t e s International peer-reviewed journal
  2. 2. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 78 environment [3, 4]. Heavy metals, Hg2+ , Pb2+ and Cd2+ Due to the demerit of conventional method, biosorption has provided an alternative measure to physicochemical methods. Recently, low cost agricultural by-products have been used to heavy metals from aqueous solution. This include maize cob and husk [6, 7, 8]; cassava waste [9]; sawdust and coconut fibre [8]; fluted pumkin [10] and so on. In this study, the adsorption isotherm for the bioremediation of Hg have health implications which include kidney dysfunction, mental retardation, cancer, hepatic damage and hypertension [5]. 2+ ,Pb2+ and Cd2+ ions on unmodified and ester modified Thais coronate and Senilia Senilus biomass were studied. The effect of concentration of the adsorbate on the adsorbents used was also investigated. MATERIALS AND METHODS Adsorption isotherm equation Temkin, Langmuir and Freundlich adsorption isotherm were used for interpreting the biosorption equilibrium of the metal ions. [11, 12]. The classical Langmuir equation is given as follows: q = (QmaxbCe)/(1 + bCe Where, q = quantity of heavy metal ion adsorbed in milligrams per gram of the adsorbent used. ) (1) Ce Q = final concentration of metal ion (mg/l) in the solution. max b = equilibrium constant related to the affinity of the binding sites for the metals. = maximum amount of metal ions adsorbed per unit weight of adsorbent. Equation (1) can be linearised as follows: 1/q = (1/qmax) + (1/qmaxb)(1/Ce The Langmuir isotherm represents the equilibrium distribution of metal ions between the solid and liquid phases. The essential characteristic of the Langmuir isotherm can be expressed in terms of a dimensionless constant, separation factor or equilibrium parameter, R ) (2) L R , which indicate the shape of the isotherm and is defined as follows [13]: L = 1/(1+ bCo Where b is the Langmuir constant and C ) (3) o is the initial concentration of the metal ions. The RL The classical Freundlich equation is given as follows: values between zero and 1 indicate favourable adsorption [14]. q = KfCe1/n Where, q = quantity of heavy metal adsorbed on the adsorbent (mg/g) (4) Ce K = final concentration of metal (mg/l) in the solution f n = an empirical constant that provides an indication of the intensity of adsorption [15] = an empirical constant that provdes an indication of the adsorption capacity of the adsorbent. Equation (4) can be linearised as follows: log q = log Kf + (1/n)logCe The adsorption constant (K (5) f and 1/n) were obtained by plotting log q as a function of log Ce n values between 1 and 10 represents beneficial adsorption [16]. [17], reported that the values of K . f The classical Temkin equation is given [12] as follows: and n determine the steepness and curvature of the isotherm. Freundlich equation is suitable for a highly heterogeneous surface and homogeneous surface, and an adsorption isotherm lacking a plateau, indicating a multi-layer adsorption [18]. X = a + blnCe Where, C (6). e X = amount of metal ion adsorbed per unit weight of adsorbent (mg/g) = concentration of adsorbate in solution at equilibrium (mg/gl)
  3. 3. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 79 a & b = are constants related to adsorption capacity and intensity of adsorption. The adsorption constants a and b were obtained by plotting lnCe against X. Collection and preparation of samples The marine animal shells was collected from Okirika village of Rivers state of Nigeria and was washed thoroughly, clean of adhering dirt, rinsed thoroughly with de-ionized water and dried in the oven at 105 oC for two days. The process helped to remove moisture present in the material, which was different from the chemisorbed water normally, released during carbonization reactions of elevated temperature. Higher temperature of 150 o H C was used to ensure complete dehydration. The purpose of dehydration was to effect de-sorption of physically absorbed water which may catalyze the decomposition of the char carbon thereby producing a very low carbon. 2O + C ------------ H2 After oven drying, the sample was macerated into powdered form. The powdered form of the sample obtained was first sieved through a 1000 µm mesh and then through 500 µm meshes. + CO Chemical activation of the adsorbent The sieved sample was soaked in 0.3 M HNO3 for 24 hours at room temperature. The adsorbents was then filtered through what man no. 41 filter paper and rinsed thoroughly with de- ionized water to maintain a pH of 7.4. The rinsed adsorbent was kept in an oven at 100oC for 12 hours for the moisture and finally stored in a tight plastic container. The treatment of the absorbent with 0.3 M HN03 aids to oxidize the adhering organic material, removal of any debris or soluble bio-molecules that might interact with the metal ions during the sorption. This process is called chemical activation. Chemical modification of the absorbent The oven dried chemical activated sample was weighed and divided into two parts. 200g of first part was left untreated was labeled the unmodified sea animal shell A and B (USASA and USASB) where A is shell of Senilia Senilus (Anadara) and B is Thais Coronata (Grastropoda) biomass. 400g of second part was treated with 5 dm3 of 3 M Oxalic acid solution for 24 hours at 28o C in a well ventilated place according to the method of [19]. The biosorbent was then esterified [15, 20] by suspending the adsorbent in 2.6 L of ethanol and 240 Ml of concentrated hydrochloric acid. The mixture was shaken for 5 hours at 150 rpm, filtered and the residue was washed thoroughly with distilled water to maintain pH of 6.9 and finally oven dried at 100o C, stored and was labeled modified sea animal shell A and B (MSASA and MSASB). Surface functional group can be introduced via chemical modification [19, 15 , 20]. All reagents used were analytical grades, purchased and used without further purification. Effect of metal ion concentration The metal ions solution with standard concentrations of 2 mgL-1, 4 mgL-1, 8 mgL-1 and 10 mgL-1 were made from analytical grade standards Cd2+ ( from CdCl2 ), Pb2+ from (Pb(NO3)2 ), and Hg(II) from ( HgCl2 ). 2g sample of the adsorbents both modified and unmodified of particle size 500 µm were put into 100 Ml solutions of each of the various metal ion solutions of different initial concentrations prepared above in a conical flask. The samples were left to stand for 10 minutes in a rotary shaker at a constant speed of 150 rpm, at a temperature of 29o C. At the end of the time, the mixtures were filtered and the various metal ions content of the filtrates were determined by AAS.
  4. 4. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 80 RESULTS AND DISCUSSION Fig. 1: Effect of concentration for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using USASA and USASB Fig. 2: Effect of concentration for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using MSASA and MSASB Fig. 3: Langmuir plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using USASA and USASB 96.000 96.500 97.000 97.500 98.000 98.500 99.000 99.500 100.000 0 2 4 6 8 10 12 %adsorbed Concentration (mgL-1) USASA Hg(II) USASA Pd(II) USASA Cd(II) 96.000 96.500 97.000 97.500 98.000 98.500 99.000 99.500 0 2 4 6 8 10 12 %adsorbed Concentration (mgL-1) MSASA Hg(II) MSASA Pb(II) MSASA Cd(II) 0.00000 0.00020 0.00040 0.00060 0.00080 0.00100 0 0.1 0.2 0.3 0.4 Ce/qe(mgl) Ce (mgL-1) USASA Hg(II) USASA Pb(II) USASA Cd(II)
  5. 5. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 81 Fig. 4: Langmuir plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using MSASA and MSASB Fig. 5: Freundlich isotherm plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using USASA and USASB Fig. 6: Freundlich isotherm plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using MSASA and MSASB 0.00000 0.00010 0.00020 0.00030 0.00040 0.00050 0.00060 0.00070 0.00080 0.00090 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 Ce/qe(mgl) Ce (mgL-1) MSASA Hg(II) MSASA Pb(II) MSASA Cd(II) MSASB Hg(II) 0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 -6.000 -5.000 -4.000 -3.000 -2.000 -1.000 0.000 lnqeln ce USASA Hg(II) USASA Pb(II) USASA Cd(II) USASB Hg(II) 0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 -5.000 -4.000 -3.000 -2.000 -1.000 0.000 lnqe ln ce MSASA Hg(II) MSASA Pb(II)
  6. 6. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 82 Fig. 7: Temkin isotherm plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using USASA and USASB Fig. 8: Temkin isotherm plot for the adsorption of Hg2+, Pb2+ and Cd2+ ions from aqueous solution using MSASA and MSASB Table 1: Values of Freundlich constants for the adsorption of Hg2+,Pb2+,and Cd2+ Metal ions ions from aqueous solution using USASA and MSASA USASA MSASA K 1 / n r² K 1 / n r² Hg(II) 763.87 0.4332 0.9999 863.76 0.5657 0.9961 Pb(II) 746.05 0.469 0.9823 965.46 0.6553 0.9939 Cd(II) 937.86 0.4933 0.9734 924.91 0.5587 0.9709 0.000 100.000 200.000 300.000 400.000 500.000 600.000 -6.000 -5.000 -4.000 -3.000 -2.000 -1.000 0.000 qe(mg/g) ln ce USASA Hg(II) USASA Pb(II) USASA Cd(II) USASB Hg(II) 0.000 100.000 200.000 300.000 400.000 500.000 600.000 -5.000 -4.000 -3.000 -2.000 -1.000 0.000qe(mg/g) ln Ce MSASA Hg(II) MSASA Pb(II) MSASA Cd(II) MSASB Hg(II)
  7. 7. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 83 Table 2: Values of Freundlich constants for the adsorption of Hg2+,Pb2+, and Cd2+ ions from aqueous solution using USASB and MSASB USASB MSASB Metal ions K 1 / n r² K 1 / n r² Hg(II) 759.45 0.4618 0.9989 882.46 0.5437 0.9831 Pb(II) 765.32 0.4361 0.9723 786.11 0.5003 0.9542 Cd(II) 1004.25 0.5472 0.9569 951.84 0.588 0.9743 Table 3: Values of Langmuir constants for the adsorption of Hg2+,Pb2+, and Cd2+ ions from aqueous solution using USASA and MSASA USASA MSASA Metal ions KL(dm3 qmaxg) r² S KF QmaxL r² S Hg(II) F 0.056 555.556 0.9685 0.816993 0.1333 646.967 0.9638 0.556234 Pb(II) 0.118 588.235 0.9071 0.679348 0.2308 769.23 0.971 0.519967 Cd(II) 0.059 568.232 0.9897 0.809061 0.1333 666.667 0.938 0.652231 Table 4: Values of Langmuir constants for the adsorption of Hg2+,Pb2+,and Cd2+ ions From aqueous solution using USASB and MSASB USASB MSASB Metal ions KL(dm3 qmaxg) r² S KF qmaxL r² S Hg(II) F 0.118 588.235 0.9527 0.679348 0.133 666.667 0.9638 0.652742 Pb(II) 0.118 588.235 0.9002 0.679348 0.133 666.667 0.8102 0.652742 Cd(II) 0.125 625 0.9913 0.666667 0.143 714.286 0.9358 0.636132
  8. 8. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 84 Table 5: Values of Temkin constants for the adsorption of Hg2+,Pb2+,and Cd2+ ions From aqueous solution using USASA and MSASA. USASA MSASA Metal ions a b r a2 B r Hg(II) 2 551.69 102.42 0.9481 566.76 123.39 0.9561 Pb(II) 539.9 108.21 0.8875 608.99 155.86 0.9632 Cd(II) 610.92 120.54 0.9823 597.04 132.01 0.9213 Table 6: Values of Temkin constants for the adsorption of Hg2+,Pb2+,and Cd2+ ions from aqueous solution using USASB and MSASB. USASB MSASB Metal ions a b r a2 B r Hg(II) 2 548.46 108.46 0.9364 581.98 134.34 0.9592 Pb(II) 545.95 100.53 0.8698 550.3 114.59 0.8467 Cd(II) 631.03 135.05 0.9884 604.01 139.02 0.9271 The effect of concentration of the adsorbates was illustrated in figure 1 and 2. The results were found to be highly concentration dependent. The percentage removal efficiency shows a decreasing trend with increasing concentration of the adsorbate. At concentration of 10 ppm, the removal efficiency rarely falls below 80% for the Hg(II), Pb(II), and Cd(II) ions. Decrease in sorption percentage at higher concentrations might be due to the relatively smaller numbers of active sites available at higher adsorbate concentrations. But with increasing of the initial concentration of the adsorbate, the total amount of metal ions removal in mg/g is increased. The decrease in percentage removal can also be explained by the fact that as the concentration of the adsorbate increases so does the metal loading on the adsorbent. For example, a concentration of 10 ppm will have higher surface loading as compared to concentration of 2 ppm or 4 ppm. Because it causes an equal increase in number of metal ions coming in contact with the adsorbent increases during same time while on the other hand the number of adsorbing sites available for adsorption are constant for all concentration. So, when the concentration is higher, more number of ions will be competing for same adsorption sites and will go through without being adsorbed. The adsorption data obtained with the adsorbent correlates well with the Frundlich, Langmuir, and Temkin adsorption models and were illustrated in figure 3 to 8. The Langmuir equation was chosen for the estimation of maximum adsorption capacity corresponding to complete monolayer coverage on the biomass surface [21]. The Langmuir model assumes the surface of the sorbent to be homogenous and the sorption energies to be equivalent for each sorption site. The essential characteristics of the Langmuir model can be expressed in terms of a
  9. 9. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 85 dimensionless constant, separation factor or equilibrium parameter, RL. From the results in table 3 to 4, the RL values were found to be greater than zero and less than one i.e 0 < RL < 1. According to [14], RL Freundlich model was chosen to estimate the adsorption intensity of the sorbent towards the sorbate. [21]. K value between 0 and 1 indicates favorable adsorption. This means that a favorable adsorption was observed in this study. F, and n determine the curvature and steepness of the isotherm [8]. The values of n also indicate the affinity of the sorbent towards the biomass. The values of n, KF and r2 The values for the constant and r were shown on table 1 and 2. The 1 / n values ranged from 0.4332 – 0.4933 USASA; 0.5587 – 0.6553, MSASA; 0.4361 – 0.5472, USASB; and 0.5003 – 0.5880. The values of 1/n for the unmodified samples were less than the modified samples. These suggest that the unmodified adsorbents had a greater sorption capacity than the modified adsorbents. Also, the value of n is greater than unity for the metal ions indicating that adsorption of the metal ions were favorable. 2 for Temkin isotherm is presented in table 5 – 6. The r2 values ranged from 0.8875 – 0.9823, USASA; 0.9213 – 0.9632, MSASA; 0.8698 – 0.9884, USASB; and 0.8467 – 0.9592, MSASB. Examination of these plots suggests that the Freundlich, Temkin and Langmuir isotherm fit the experiment but Freundlich isotherm is a better model than Langmuir and Temkin isotherm with respect to their r2 values which is greater than 0.9000 and less than 1. CONCLUSION Senilia Senilus and Thais Coronata biomass are agricultural waste, which are found to be useful for the removal of heavy metal from aqueous solution. The adsorption capacity increased with increasing concentration of the adsorbate. Freundlich adsorption isotherm proved best fit, followed by the Langmuir isotherm and then Temkin isotherm. The modification of the adsorbent using esterification have been shown not to enhance the adsorption capacity, probably, this is attributed due to ester groups attached to the adsorbents. References 1. Amuda, O.S. and Ibrahim, A.O. (2006). Afri. Journ. Biotechnol. 5(16): 1483 – 1487. 2. Ceribasi, H.I. and Yetis, U. (2001). Water S.A. 27(1): 15 – 20. 3. Reed, B.F., Arnnachalam, S., and Thomas, B. (1994). Removal of Lead and Chromium from aqueous waste streams using Grannular activated carbon (GAC) columns. Environ. Prog. 13: 60 – 65. 4. Faisal M., and Hasnain, S. (2004). Microbia conversion of Cr(vi) into Cr(iii) in industrial effluent. African J. Biotechnol. 3(11): 610 – 617. 5. Klaassen, C.D. (2001). Heavy metal and Hardmen J.G., Limbird, L.E., Gilman A.G. (eds.). Goodman and Gilmans: The pharmacological Basis of Therapeutics, McGraw Hill, New York. Pp. 1851 – 1875. 6. Igwe J. C. and Abia A. A. (2003) Maize Cob and Husk as adsorbents for removal of Cd, Pb and Zn ions form wate water. Trhe physical scientist, 2; 83-945 7. Igwe, J. C., and Abia A. A. (2005). Sorption Kinetics and intraparticulate diffusivities of Cd, Pb and Zn ions on maize cob. Afr. J. Biotehc. 4(6): 509 – 512. 8. Igwe J. C., Ogunewe D. and Abia A. A. (2005). Competitive adsorption of Zn (II), Cd (II) and Pb (II) ions form aqueous and non-aqueous solution by maize cob and husk. Africa J. of biotehcnol. Vol. 4 (10 pp. 1113 – 1116). 9. Horsfall M. Jr., and A. A. Abia (2003). Sorption of Cadium and zinc (II) ions form aqueous solutions by cassava waste biomass (Manihot sculenta Cranz) water Res. 37, 4913.
  10. 10. Osu Charles I. and S.A. Odoemelam, 2012. Adsorption Isotherm Studies of Hg(II), Pb(II), and Cd(II) Ions Removal from Aqueous Solutions Using Unmodified and Ester Modified (Esterified) Senilia senilus and Thais coronata Biomass. Journal of Applied Technology in Environmental Sanitation, 2 (2): 77-86. 86 10. Michael Horsfall I. and Ayebaemi Ibuteme Spiff (2005). Adsorption of transition metals in aqueous solutions by fluted pumpkin Telfairia occidentals Hookf) waste. Chemistry and biodiversity vol. 2 pp 1266 – 1276. 11. Atkins, P. and de Paula, J. (2003). Atkins’ Physical Chemistry. Oxford Unievrsity Press. Seventh edition. Indian edition. 12. Abdel-Ghani, N.T., Hefney, M., El-Chaghaby, G.A.F. (2007). Removal of Lead from aqueous solution using low cost abundantly available adsorbents. Int. J.Environ. Sci. Tech. 4(1): 67 – 73. 13. Ahalya, N., Kanamadi, R.D., Ramachandra, T.V. (2005). Biosorption of chromium (Vi) from aqueous solutions by the husk of Bengal gram (Cicer arientinum). Electron. journ. Biotechnol. 8(3): 258 – 264. 14. Mckay, G., Blair, H.S., Gardener, J.R. (1982). Journal of applied polymer Science, 27(8): 3043 – 3057. 15. Krishnakumar Parvathi; Ramachandramurthy Nagendran and Redhakrishnan Nreshkumar(2007) Lead biosorption onto waste beer yeast by-product, a means to decontaminate effluent generated form artery manufacturing industry. Electron. J. of biotehcnol. Vol. 10. No. 92 – 104. 16. Kairvelu, K., Namasivayam, C. (2000).Environmental technology 21(10): 1091 – 1097. 17. Akgerman, A., Zardkoohi, M. (1996). Eng.Data 41: 185 – 191 18. Juang, R.S., Wu F.C., Tseng R.L. (1996). J. chem. Eng. Data: 487 – 492. 19. Okieimen, C. O., Okiemen, F. E., (2001). Enhanced metal sorption by groundnut (Arachis Iypugea) Husks modified with thioglycolic Acid. Bulletin of Pure and Applied Sciences 20 c (i), 13 – 20. 20. Drake, Lawrence R., Lin, Shan; Rayscon, Gary D. and Jackson, paul J, (1996) Chemical modification and metal binding studies of Datura innoxia, Envroenmental Sicnece and Tehncology, Vol. 30 (i); 110 – 114. 21. Gang, S. and Weixing, S. (1998). Sunflower, Stalks as Adsorbents for the Removal of metal ions form waste water. Ind. Eng. Chem. Res. Vol. 37, No 4, 1324 – 1327.

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