| 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 phase. Effects of PMS concentrations, Co2+- concentrations and various inorganic anions (H2PO-4, HCO-3, NO-3, 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 H2PO-4 had positive effect on the degradation of Imidacloprid, low concentration HCO-3 had positive effect and high concentration HCO-3 had negative effect, Cl- had negative effect, while NO-3 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 SO·-4 induced by homogeneous Co/PMS was proposed accordingly. |
