Investigation of Photo–Fenton–Like Process Efficiency in Diazinon Pesticide Removal from Aqueous Solutions

Diazinon pesticide and its metabolites have been identified in aquatic systems worldwide. It was related to toxicity for aquatic organisms, animals, and humans. Waters contaminated with such persistent insecticides should be treated with suitable treatment processes. In this research, Diazinon removal from aqueous solutions by the photo–Fenton–like process (UV/H2O2/Fe0) was investigated. This experimental laboratory scale study was performed on synthetic wastewater in a batch system. The reaction was done in the cylindrical UV irradiation photo–reactor with 2.5 L useful volume at 25 ±2 °C. The effects of H2O2, pH, ZVI, retention time and initial Diazinon concentration on removal efficiency were studied. The results showed that the optimal parameters for this process were as follows: [Fe0]/[H2O2] molar ratio of 1:1, pH 4, the reaction time of 30 min, and initial concentration of 10 mg/L. Diazinon removal and COD reduction in this condition were achieved 83.05% and 71.34%, respectively. Photo–Fenton like process can be suggested as a pretreatment step for the biological removal or post treatment of Diazinon and other pesticides with a similar structure in the aqueous environments. Also, considering the high potential of the photo–Fenton–like process in the reaction with pollutants, a modifying pilot system to ensure concurrent proper rotation speed and UV radiation seem to be necessary.