Influential Factors and Degradation Pathway of Imidacloprid by Homogeneous Co/PMS System
均相Co/PMS系统降解吡虫啉的影响因素及降解途径研究

Cobaltous-mediated decomposition of peroxymonosulfate (Co/PMS) system is one of novel advanced oxidation technologies (AOTs), which leads to the formation of very strong oxidizing species in aqueous. Effects of PMS concentrations, Co2+ concentrations and various inorganic anions (H2PO4?, HCO3?, NO3?, Cl?) on the degradation of Imidacloprid induced by Co/PMS system was investigated as emphasis. The degradation kinetics of Imidacloprid followed pseudo first-order kinetics and reaction rates related to PMS and Co2+ concentrations. The reaction rates increased with increasing PMS] and Co2+] when the other parameters were constant. However, the decrease of degradation rates was found when the molar ratio of PMS versus Imidacloprid was over 20. The effects of H2PO4? had positive effect on the degradation of Imidacloprid, low concentration HCO3? had positive effect and high concentration HCO3? has negative effect, Cl? had negative effect, while NO3? had little effect. Based on the results of GC/MS, two main intermediates were identified, 6-chloronicotinic acid and 6-chloronicotinamide, and the reaction pathway for SO4?? induced by homogeneous Co/PMS was proposed accordingly.