Degradation of diazinon by dielectric barrier discharge plasma

Abstract

Pesticides are chemical compounds widely used in crop pest control, ensuring high productivity and product quality control. However, pesticides are toxic and can be bioaccumulative, and their excessive use causes environmental and health impacts. In this study, the potential of atmospheric cold plasma to degrade diazinon present in water was investigated. For the degradation process, a dielectric barrier discharge (DBD) plasma system was used to process diazinon at a varying voltage (10, 15, and 20 kV), excitation frequency (200, 400, 600, 800, and 1000 Hz), and exposure time (10, 20, and 30 min). The concentration of diazinon and the identification of the by-products were analyzed by gas chromatography coupled to mass spectrum (GC-MS). DBD plasma processing efficiently degraded diazinon, reaching a maximum degradation of 9.44 ± 0.09 mg/L, sufficient to bring diazinon-contaminated waters to safe levels. Analysis of variance indicated that increasing voltage and treatment time and low plasma excitation frequencies increased diazinon degradation. Two parallel degradation routes were proposed for diazinon degradation by cold plasma consisting of an oxidative desulphurization route and a hydrolytic route followed by a ring-opening reaction.