A Novel Material for Removal of Organochlorine Pesticides from Aqueous Environment: Kinetics and Thermodynamics Investigations
Abdul Ghaffar, Azhar Mashiatullah and Naveed IqbalAffiliation:
IAD, Pakistan Institute of Nuclear Science & Technology, P.O. Nilore Islamabad, Pakistan.
AbstractChitosan Grafted Silica (CGS) material was prepared by using tetraethyl-orthosilicate as grafting and/or cross linking agent. The structural of the material was characterized by SEM (scanning electron microscopy), FTIR (Fourier transform infrared Spectroscopy), and BET (Brunauer, Emmett and Teller) analysis. The synthesized material was proved an excellent sorbent for the removal of organo-chlorine pesticides (OCPs) like DDT and DDE. The higher sorption potential of the CGS was due to its high surface area, porous rigid structure and active sites such as –OH, –NH2, and –CONH2. Maximum removal of DDT (94±2.9%) and DDE (86 ±1.8 %) were achieved on CGS with agitation of 2 and 3 hours respectively, at pH 6 and 40°C. The thermodynamics data suggested an endothermic, spontaneous and higher stable sorption process with no structural changes at the solid-solution interface during the sorption. The ∆G value increased as the temperature increased up to 40oC, indicating a greater driving force resulting in higher sorption capacity. The coefficients of correlation R2 indicate that the Freundlich isotherm fitted the sorption data better than the Langmuir isotherm, suggesting a multilayer sorption. The Freundlich sorption isotherm suggested that the sorption of DDT was favorable as compared to DDE. The developed method was applied to actual industrial waste at laboratory level. The experimental data revealed that developed method might be employed for the removal of DDT and DDE from aqueous industrial effluents before discharging them into water bodies.
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