Type-II heterojunction Se-g-C3N4/ZnO coupled MnCo2O4 photocatalyst for enhanced levofloxacin hydrochloride degradation activated by peroxymonosulfate

Abstract

The advanced oxidation process induced by photocatalysis under visible light undoubtedly possesses greater application potential and cost-effectiveness due to the high excitation energy supply costs. Here, we proposed a novel Type-II heterojunction Se-g-C3N4/ZnO (Se-CN/ZnO) and MnCo2O4 (MCO) photocatalyst for the efficient degradation of levofloxacin hydrochloride (LEV) activated by peroxymonosulfate (PMS) under sunlight. Analysis results confirmed the oxidation process was executed by Se-CN/ZnO synergistic MCO-activated PMS for the responsive degradation of LEV, achieving a removal efficiency greater than 98.6 % within 15 min (kinetic rate constant Kobs = 0.299 min−1), under optimal conditions ([Se-CN/ZnO (300 °C)]0 = 46 mg, [MCO]0 = 1.6 mg, [PMS]0 = 0.27 mM, [Aeration rate]0 = 146 mL/min, pH = 5.5). Effective interfacial transfer and spatial segregation of the photogenerated electron-hole were attributed to the stabilized Type-II energy band structure of Se-CN/ZnO, the rapid cyclic redox of metal ions Mnn+(n = 2,3,4) and Com+(m = 2,3) promoted the activation of PMS reduction of LEV through synergistic action of various endogenous substances. Analysis of the contribution of reactive oxygen species by electron paramagnetic resonance substantiated the dominant role of ·OH and O2·-, and the superiority of the degradation process was further validated with the analysis of the non-toxic and ecological safety characteristics of intermediates. The recommended method of eco-friendly and stable catalytic performance of LEV has engineering application prospects that are incomparable to many publicly available treatment methods.