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E-Journal of Chemistry
Volume 6, Issue 3, Pages 713-724

Sorptive Response Profile of Chitosan Coated Silica in the Defluoridation of Aqueous Solution

Y. Vijaya and A. Krishnaiah

Biopolymers and Thermophysical Laboratories, Department of Chemistry, Sri Venkateswara University, Tirupati-517 502, A.P., India

Received 16 October 2008; Accepted 12 December 2008

Copyright © 2009 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


As excess of fluoride (> 1.5 mg/L) in drinking water is harmful to the human health, various treatment technologies for removing fluoride from groundwater and aqueous medium have been investigated in the past. Present investigation aims to develop chitosan coated silica (CCS) and to investigate the removal of fluoride by CCS through adsorption. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermo gravimetric analysis (TGA), X-ray diffraction (XRD) were used for the characterization of the sorbent. The surface morphology of the CCS was observed using SEM. Series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The factors investigated include the influence of pH, contact time, adsorbent dose and initial fluoride concentration. The studies revealed there is an enhanced fluoride sorption on CCS. The sorption data obtained at optimized conditions were subjected to Langmuir and Freundlich isotherms. The monolayer sorption capacity, Q° (44.4 mg/g) and binding energy b (0.010 L/mg) have been estimated using Langmuir isotherm. The kinetic studies indicate that the sorption of fluoride on CCS follows Pseudo second-order kinetics.