Role of peroxymonosulfate on enhancing ozonation for micropollutant degradation: Performance evaluation, mechanism insight and kinetics study

The enhancement performance, mechanisms and kinetic study of peroxymonosulfate (PMS) towards ozonation via prometon (PMT) degradation have been comprehensively investigated via the semi-continuous experiments in the present study. The removal of PMT ( > 97.34%) and the pseudo-first-order rate constant (k = 0.6095 min(-1)) were achieved after 7 min reaction with 7.5 mg min(-1) O-3 and 100 mg L-1 PMS at pH 6.5. Meanwhile, the PMT degradation performance was systematically evaluated in terms of inlet O-3 concentration, PMS dose, solution pH, water matrix species and etc. It was notable that pH played a significant role on the PMT degradation efficiency in O-3/PMS process, especially under the neutral and alkaline conditions. The mechanism of the synergistic effect was subsequently explored by the radical scavengers and electron paramagnetic resonance experiments, confirming that both( center dot)OH and SO4 center dot- were the dominant reactive radicals in O-3/PMS process. In addition, the second-order rate constants of PMT with (OH)-O-center dot and SO4 center dot- were determined to be 1.9 x 10(9) M-1 s(-1) and 1.7 x 10(9) M-1 s(-1) via competition kinetics for the first time. Moreover, the plausible degradation pathways of PMT were elucidated based on the seventeen transformation by-products detected. Furthermore, a modified kinetic model was put forward to quantify the relative contribution of (OH)-O-center dot and SO4 center dot-, in order to accurately predict the degradation rate of PMT in O-3/PMS process. This investigation could provide a promising alternative in developing more efficient O-3-based advanced oxidation process and supply a feasible approach for water decontamination.