Bisphenol S degradation by visible light assisted peroxymonosulfate process based on BiOI/B4C photocatalysts with Z-scheme heterojunction

Abstract In this study, we developed the BiOI based photocatalytic activation of peroxymonosulfate technology by synthesized Z-scheme heterojunction BiOI/B4C (BOBC). The BOBC could remove 90.4% of bisphenol S (BPS) in 30 min under optimal condition ([BOBC-24-5]0 = 0.1 g/L, [PMS] = 0.05 mmol/L, pH = 7) and had good reusability. Meanwhile, the results of control experiments indicated that the synergistic effects resulted in higher activity than single photocatalysis system and single peroxymonosulfate system. From the characteristic results, the Z-scheme heterojunction formed by hydrothermal method improved the separation efficiency of photogenerated electron and hole pairs, thereby increasing the content of active free radicals in the system and improving the degradation efficiency of BPS. Free radical quenching experiments and electron spin resonance showed that O2•−, h+, •OH and SO4•− played important roles in the system. The photogenerated electrons and holes generated by the photocatalyst under visible light activated PMS and generated free radicals to degrade BPS. Based on the intermediates identified by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometer/mass spectrometer (UPLC-QTOF-MS/MS), the possible degradation pathways of BPS were proposed. This work provided a new reference for improving the oxidation efficiency of peroxymonosulfate assisted by visible light.