Degradation and mineralization of diazinon pesticide by G/PbO2 anodic oxidation process

Abstract

The high toxicity and bio-stability of organochlorine pesticides have made organophosphorus pesticides (OPPs) more preferred today. Diazinon is one of the most widely used insecticides in the group of OPPs, which has high stability in the environment and causes neurobehavioral side effects in case of long-term exposure to humans. The present study aims to fabricate the PbO2 electrocatalyst on a graphite sheet (G/PbO2) and use it as a non-active anode for diazinon degradation. The effect of independent variables such as solution pH, current applied to the electrodes, initial concentration of diazinon and reaction time on the removal efficiency of the pesticide was studied. SEM and XRD results showed that lead dioxide crystals in the β-PbO2 phase were formed as compact pyramidal clusters on the surface of the anode. At solution pH 8, diazinon removal efficiency was significantly improved. However, in mild operating conditions (solution pH = 5 and a current = 0.4 A), diazinon removal efficiency with initial concentrations of 20 and 100 mg/L after 90 min of reaction was 100% and 70%, respectively. After optimizing the independent variables effective in the diazinon removal, the mineralization pathway was proposed considering intermediates identified by LC-MS analysis. The results of the present study confirm that anodic oxidation with PbO2 electrocatalyst can be an effective method for the degradation and mineralization of diazinon pesticide.