Efficient degradation of ciprofloxacin by magnetic γ-Fe2O3-MnO2 with oxygen vacancy in visible-light/peroxymonosulfate system.

Abstract

In this work, the magnetic γ-Fe2O3-MnO2 bifunctional catalyst with oxygen vacancy was synthesized for peroxymonosulfate (PMS) activation under visible light. The activity of γ-Fe2O3-MnO2 was investigated by ciprofloxacin (cipro) degradation. Results showed that 98.3% of cipro (50\xa0μM) was removed within 30\xa0min in visible-light/PMS system mediated by γ-Fe2O3-MnO2 (2:1) with fine-tuned oxygen vacancy. The cipro degradation data fitted well with pseudo-first-order kinetic model with the highest kinetic constant of 0.114 min-1. Besides, the γ-Fe2O3-MnO2 exhibited stability, recyclability and practicability. High selectivity for cipro degradation was observed with coexisting anions in visible-light/γ-Fe2O3-MnO2/PMS system. Furthermore, the enhanced mechanism of PMS activation under visible light with γ-Fe2O3-MnO2 was proposed. The appropriate oxygen vacancy enhanced the separation of photo-induced carriers and Z scheme heterostructure maintained the highest redox potential. Accordingly, the synergistic effect of photocatalysis and PMS activation enhanced cipro degradation. Free radical and non-radical species including , h+, 1O2, •OH and co-existed in the coupled system. Impressively, this study provides a handy approach for oxygen vacancy regulation in metallic oxides composite and an easily recycled catalyst with high-activity in coupled oxidation system towards antibiotic degradation.