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Optimization and kinetic studies for degradation of insecticide monocrotophos using LR grade and P25 TiO2 under UV/Sunlight conditions



Photocatalytic degradation of monocrotophos (MCP), an organophosphorous insecticide, present as a severe contaminant in surface water was studied in slurry batch photoreactor by using Aeroxide P-25 and LR (laboratory reagent) grade TiO2 as catalysts. Effect of varying parameters such as initial concentration, catalyst loading, area/volume ratio, pH of the solution, light conditions and intensities, and types of the catalyst has also been studied. Aeroxide P25 showed better degradation efficiency than LR grade TiO2 in both UV and sunlight conditions under optimized parameters. Optimum degradation of 25 ppm MCP was observed under UV light (30 W m−2), at solution pH 5 and catalyst loading of 2.5 g L−1 in both catalyst (LR & P25) cases. Chemical oxygen demand (COD) analysis of samples was performed in order to authenticate the mineralization of MCP. The disappearance of MCP in slurry reactor obeys first order kinetics. The rate of degradation shows a notable enhancement (15%) by the addition of small quantities of oxidant (H2O2) in sample solution with LR TiO2, under both UV and sunlight conditions. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1201–1208, 2014