Enhanced removal of bisphenol S in ozone/peroxymonosulfate system: Kinetics, intermediates and reaction mechanism

The degradation process of bisphenol S (BPS) in ozone/peroxymonosulfate (O 3 /PMS) system was systematically explored. The results showed that the removal efficiency of BPS by O 3 could be significantly improved with addition of PMS. Compared with ozonation alone, the pseudo-first-order constant ( k obs ) was increased by 2–5 times after adding 400 μM PMS. In O 3 /PMS system, accelerated removal of BPS was observed under neutral and alkaline conditions. The removal efficiency of BPS reached 100% after 40 s of reaction at pH 7.0, with the k obs of 0.098 s −1 . Moreover, Cu 2+ had a catalytic effect on the O 3 /PMS system, because it could catalyze the decomposition of ozone and PMS to produce •OH and SO 4 •- , respectively. Electron paramagnetic resonance illustrated that •OH and SO 4 •- were the reactive species in O 3 /PMS system. Twelve intermediates were identified by mass spectrometry, and the degradation reactions in O 3 /PMS system mainly included hydroxylation, sulfate addition, polymerization and β-scission. Finally, the toxicity of the products was evaluated by the EOCSAR program. Our results introduce an efficient method for BPS removal and would provide some guidance for the development of O 3 -based advanced oxidation technology .