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/PMS) system was systematically explored. The results showed that the removal efficiency of BPS by O could be significantly improved with addition of PMS. Compared with ozonation alone, the pseudo-first-order constant (k) was increased by 2-5 times after adding 400 μM PMS. In O/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 of 0.098 s. Moreover, Cu had a catalytic effect on the O/PMS system, because it could catalyze the decomposition of ozone and PMS to produce •OH and SO, respectively. Electron paramagnetic resonance illustrated that •OH and SO were the reactive species in O/PMS system. Twelve intermediates were identified by mass spectrometry, and the degradation reactions in O/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-based advanced oxidation technology.