Abstract

Chitosan Grafted Silica (CGS) material was prepared by using tetraethyl-orthosilicate as grafting and/or cross linking agent. The structure of the material was characterized by SEM (Scanning Electron Microscopy), FTIR (Fourier transform infrared Spectroscopy), and BET (Brunauer, Emmett and Teller) analysis. The higher sorption potential of synthesized material for organo-chlorine pesticides (OCPs) like DDT and DDE was attributable to its large surface area, porous rigid structure and active sites such as –OH, –NH₂, and –CONH₂. Most removal of DDT (94±2.9%) and DDE (86 ±1.8%) was achieved at 40°C and pH 6 with agitation of 2 and 3 hours, respectively. The thermodynamics data suggested an endothermic, spontaneous and higher stable sorption process with no structural changes at the solid-solution interface. The ΔG value was increased with an increase in temperature up to 40°C, indicating a greater driving force ensuing a higher sorption capacity. The co-efficient of correlation (R²) suggested that the sorption data was best fitted in Freundlich isotherm rather than the Langmuir isotherm, indicating a multilayer sorption. The Freundlich sorption isotherm proposed a favorable sorption of DDT as compare to DDE. The developed method was applied to real 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.

Keywords: DDT & DDE, remediation and kinetics, thermodynamics parameters, waste treatment application.