Potoccatalytic oxidation of oganophosphorus pesticides using zinc oxide

Abstract In recent years, the application of heteroge-neous photocatalytic water treatment processses has gained wide attention due to its effectiveness in degra-ding and mineralizing the pesticides. These pesticides are often found in many surface and groundwater sources and their concentration levels often exceed the drinking water permissible limits recommended by Iran and European drinking water standards. The aim of the present study was to investigate the influence of various parameters such as initial malathion and diazinon concentration catalyst amount, initial pH of the reaction medium and pesticide types on the photocatalytic decomposition of pesticides in the presence of ZnO using an ultraviolet lamp as the light source. The best conditions for the photocatalytic degradation of pesticides were obtained. Results showed that the optimal concentration of catalyst was found to be 100 mg. L -1 . The photodegradation efficiency of pesticides increases with the increase of the illumination time. The photodegradation rate of pesticides was higher in alkaline than in acidic conditions. The photocatalytic degradation rate of the malathion was more than diazinon. The photodegradation efficiency decreases with the increase in the initial concentration of pesticides. The photocatalytic system afforded the highest removed percentage at initial concentration for diazinon and malatlion were 100 and 200 mg.L-1 respectivel