Degradation Effect and Mechanism Analysis of Pesticides Imidacloprid and Thiamethoxam by Electron Beam Irradiation
In order to further analyze the mechanism of pesticide irradiation degradation,the irradiation degrada-tion effects and influencing factors of typical neonicotinoid pesticides imidacloprid and thiamethoxam from 1 kGy to 5 kGy absorbed dose were studied by electron beam irradiation degradation technology,and the degradation path-way and mechanism of pesticides were analyzed.The results showed that the degradation rate of imidacloprid and thiamethoxam could be effectively degraded by electron beam irradiation.The degradation rate was positively cor-related with the absorbed dose and negatively correlated with the initial mass concentration of pesticides.The neu-tral solution and low hydrogen peroxide concentration could promote the degradation of pesticides.Through the analysis of irradiation products and their degradation pathways,it was found that imidacloprid and thiamethoxam mainly rely on·OH radical,·H radical and hydrated electron eaq-to degrade n-nitroimidazolidane structure and tetrahydrooxadiazine structure.These free radicals and hydrated electrons are produced by irradiation and can promote the degradation of pesticides.The final degradation products of imidacloprid and thiamethoxam were 6-chloronicotinic acid and 2-chlorothiazole-5-methylamine,respectively.
electron beam irradiationneonicotinoid pesticidesdegradation productsdegradation effectdegra-dation mechanism
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