Peroxymonosulfate activation by surface-modified bismuth vanadate for ciprofloxacin abatement under visible light: Insights into the generation of singlet oxygen.

[Display omitted] • Surface-modified bismuth vanadate is prepared for PMS activation under visible light. • CIP oxidation in BVO-2/PMS/Vis system is dominated by 1O 2 and photogenerated holes. • Surface C O acts as Lewis base site to induce PMS hydrolysis in acidic condition. • The efficiently separated electrons can reduce PMS for SO 4 − and OH generation. Lewis basic sites have been shown to induce singlet oxygen (1O 2) generation in metal-free catalysts while have yet to be elucidated in metal-containing bismuth vanadate (BiVO 4). Herein, surface-modified BiVO 4 photocatalysts are developed and applied in peroxymonosulfate (PMS) activation for ciprofloxacin (CIP) abatement employing 1O 2 and photogenerated holes as the primary reactive species. The surface carbonyl moiety acts as Lewis basic sites to induce PMS hydrolysis under acidic conditions for 1O 2 generation. The occurrence of electron transfer from PMS to catalyst accounts for 1O 2 generation via PMS oxidation. Moreover, PMS as an electron acceptor kinetically accelerates charge separation, not only inducing SO 4 − and OH generation but also allowing direct oxidation of CIP by efficiently separated holes. Accordingly, the optimal BVO-2/PMS/Vis system can completely degrade CIP in 9 min under visible light with a reaction rate of 0.4264 min−1, far exceeding the BVO-2/PMS (0.0063 min−1) and BVO-2/Vis (0.0411 min−1) systems. [ABSTRACT FROM AUTHOR]