International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 1(3), 55-57, October (2012) I. Res. J. Environment Sci. International Science Congress Association 55 Short Communication Chitosan for the Removal of Chromium from Waste Water Singh Dhanesh 1 and Singh Anjali 2 Deptt. of chemistry, K.G. Arts and Science College, Raigarh, C.G, INDIA School of Applied and Social Sciences, Singhania University, Pacheri Bari, Jhunjhunu, Raj, INDIA Available online at: www.isca.in Received 28th August 2012, revised 22nd September 2012, accepted 25th September 2012 Abstract The sorption of chromium (VI) on chitosan has been found to be dependent on contact time, concentration, temperature, and pH of the solution. The process of removal follows first order kinetics and absorption of heat. Keywords: Chitosan, bioabsorbent, chromium (VI), heavy metal adsorption, Chitin Introduction The general methods of treating wastewater having chromium follow precipitation and ion exchange. Recently, much interest has been exhibited in the use of sorption technique for the removal of cadmium from wastewater using chitosan. The present investigation aims at using chitosan, a low cost and highly effective sorbent for the removal of cadmium from waste water. Chitosan is a biopolymer, which is extracted from crustacean shells or from fungal biomass. The structure of chitosan is presented schematically in figure-1 Figure-1 Structure of chitosan Material and Methods Experimental Procedure: Chitosan was obtained from India sea foods, cochi India. Batch sorption experiments were carried out in temperature controlled shaking machine by agitating 25ml aqueous solutions of sorbates with 1.0 g sorbent in different glass bottles at different conditions of concentrations, temperatures and pH. The pH of different solutions was adjusted with 0.05 M NaOH or HCl by pH meter, systronic 335. The speed of agitation was maintained at 1000 rpm to ensure equal mixing. The progress of sorption was noted after each 20 min till saturation. At the end of predetermined time interval each 20 min, the sorbate and sorbent were separated by centrifugation at 16,000 rpm and the supernatant liquid analyzed by atomic absorption spectrophotometer.Results and Discussion Effect of Contact Time and Concentration: The removal of Cr (VI) by sorption on chitosan from aqueous solution increase with time (figure-2) till equilibrium is attained in 140 min. The figure show that time of saturation is independent of concentration. It is further noted that the amount of Cr (VI) sorbed increases from1.960 mg.g-1 to 5.701 mg.g-1 by increasing Cr (VI) concentration from 100 mg/l to 250 mg/l. the time-amount sorbed curve is single, smooth and continuous indicating monolayer coverage of Cr (VI) on the outer surface of chitosan. Figur-2 Effect of concentration for the sorption of chromium (VI) on chitosan;  100 mg/L,  150 mg/ L,  200 mg/L, * 250 mg/L International Research Journal of Environment Sciences_____________________________________________ ISSN 2319–1414 Vol. 1(3), 55-57, October (2012)I. Res. J. Environment Sci. International Science Congress Association 56 Sorption Kinetics: The kinetics of sorption of Cr (VI) on chitosan was studied using Lagergren equation, Log (qe –q) = log q- kt / 2.3 (1) Where q and q are the amount sorbed (mg.g-1) of Cr (VI) at equilibrium and at time‘t’ respectively and k is sorption constant. The straight lines obtained from the plots of log (q-q) against‘t’ (figure-3) and different concentrations indicate that the sorption process follows first order kinetics. Effect of Temperature: The amount of Cr (VI) sorbed on chitosan increases from 1.987 mg.g-1 to 2.488 mg.g-1 by increasing temperature from 30C to 40C indicating the process to be endothermic (figure-4). Langmuir Isotherm: The equilibrium data at the different temperatures follow Langmuir equation, /q = 1/.b + C (2) Where Ce mg.L-1 is equilibrium concentration of Cr (VI) and and b are Langmuir constants related to sorption capacity and sorption energy respectively. The value of and b (table 4) were determined from the slope and intercept of linear plots figure-5. The sorption capacity also increases with 0 temperature suggesting that the active centers available for sorption have increased with temperature. Figure-3 Lagergren plot for the sorption of Cr (VI) on chitosan;  100 mg/L,  150 mg/ L,  200 mg/L, * 250 mg/L, pH 5, temp 30C The change in free energy (), enthalpy (), and entropy ) of sorption have been calculated using following equations, = -RT lnK (3) = RT T (T – T) ln k /k (4) = - / T (5) Where K and K2 are equilibrium constants at temperature Tand T respectively. The negative values of (table 2) indicate the spontaneous nature of the sorption process. The positive values of at different temperature support the endothermic nature of the process. Figure-4 Effect of temp. On the sorption of Cr (VI) on Chitosan  30C,  40C,  50 oC Table-1 Ø Values at Different Temp and pHTemperature (°C) Ø mg.g-1 p H Ø mg.g-1 30 0.4718 2 0.0155 40 0.4439 4 0.0153 50 0.3927 6.5 0.0137 Figure-5 Langmuir isotherm for the sorption of Cr (VI) on chitosan;  30oC,  40C,  50 oC. Effect of pH: The amount of Cr (VI) sorbed on chitosan decreases from 2.298 mg.g-1 (91.92 %) to 1.598 mg.g-1 (63.92 %) by increasing pH of the solution from 2.0 to to 6.5 (figure-5). The Sorption capacity , also decrease with the increase of pH. International Research Journal of Environment Sciences_____________________________________________ ISSN 2319–1414 Vol. 1(3), 55-57, October (2012)I. Res. J. Environment Sci. International Science Congress Association 57 Figure-7 Effect of pH on the sorption of chitosan; 2.0,  4.0, 6.5; temp: 30 C, conc. 100 mg/l Table-2 Thermodynamic parameters at different temperatures Temperature (°C) G o (kcal.mol - 1) H o (kcal.mol - 1) S o (kcal.mol - 1) 30 -17.110 11.37 0.191 40 -25.27 28.10 0.708 50 -37.87 Conclusion From the above discussion it is clear that due to chemical composition, structure, more adsorption sites, cheap, availability in plenty etc. this substance will provide to be efficient adsorbent. Acknowledgement The authors are thankful to Dr. Nagesh Gaveli, Director, Sudarshan College of science, management and research, Pune (Maharashtra), for providing research facilities, co- operation and constant encouragement to carry out the work. References 1.Pandey K.K., Prasad G. Singh V.N., Fly ash China Clay for the removal of Cr (VI) from aqueous solution, Indian Journal of Chemistry,23(A), 514-515 (1984)2.Singh V.N., Singh I.S. and Singh N.P., Removal of Cu (II) from aqueous solution by fly ash. Indian Journal of Technology,22(2), 22-27 (1984)3.Vishwakarma P.P. and Singh V.N., Removal of Ni (II) by China Clay, Asian Environment, 11(3), 49-64 (1984)4.Yadav K.P., Tyagi B.S., Pandey K.K and Singh, Flyash for the treatment of Cd (II) rich effluents, Env. Tech. Letter,(8), 225- 234 (1989)5.Namasivayam C. and Yamuna R T., Environ Pollut.,9(1),1-4 (1985)6.Sekeran G., Shanmugasundaram K.A., Mariappan M. and Raghavan K.V., Indian J Chemical Technol2(311), 71-75 (1995)7.Ikhuoria and Omonmhenle S.I., Removal of heavy metals from aqueous solution by adsorption onto chemically modified pumpkin, (Telfaira accidentalisHook) Seed Husk, J. Chem. Soc. Nig.,31(1-2), 109-113 (2006)8.Gotoh T., Matsushima K. and Kikuchi K.I., Preparation of alginatechitosan hybrid gel beads and adsorption of divalent metal ions., Chemosphere,5.5(1), 135-140 (2004)9.Grosse D.N., A review of alternative treatment process for metal bearing hazardous waste streams, J. Air Pollution Contr. Assor.,36, 603-614 (1986)10.Findon A., Mckay G. and Blair H.S., Transport studies for the sorption of copper ions by chitosan, J. Environ. Sci. Health, A2 8(1), 173-185 (1993)