Abstract:In this research, photocatalytic degradation of diazinon by amino-functionalized Fe 3 O 4 -WO 3 nanoparticles under UV irradiation was investigated with variation of pH, nanocatalyst dose, initial diazinon concentration, different purging gases, H 2 O 2 concentration, and type of organic compounds. Under optimal conditions: pH=.23 % of the insecticide was removed after 120 min. A decrease was observed in the removal efficiency of diazinon in the presence of different purging gases and organic compounds. Based on the three kinetic models developed in this study, it was found that the removal of diazinon followed the first order kinetic. Also, application of the UV/amino-functionalized Fe 3 O 4 -WO 3 nanoparticles both increased the performance and decreased electric power consumption. However, 86.17 % of diazinon in real water samples was removed under the optimized conditions. Furthermore, the photocatalytic activity was kept after five successive cycles.