Photocatalytic degradability of insecticide Chlorpyrifos over UV irradiated Titanium dioxide in aqueous phase

Photocatalytic degradation of Chlorpyrifos in aqueous phase by using photocatalyst TiO₂ in the presence of artificial UV-light and sunlight was reported. Experiments were performed in both UV and solar light at optimized conditions. The degradation of insecticide was investigated in terms of reduction in COD. The effect of catalyst loading, pH, addition of oxidant on the reaction rate was ascertained and optimum conditions for maximum degradation were determined. In this case catalyst concentration was optimized at 4.0 gL⁻¹, pH 6.5 and oxidant concentration at 3.0 gL⁻¹, where 90% degradation of the insecticide was observed. Treatment under natural solar conditions showed better results as compared with UV treatment. The effect of sonication on the catalyst slurry was also studied for the better dispersion of the catalyst. The complete mineralization of pesticide from water or waste water followed first–order Langmuir-Hinshelwood (L-H) kinetic model.