Improved heterogeneous photo-Fenton-like degradation of ofloxacin through polyvinylpyrrolidone modified CuFeO2 catalyst: Performance, DFT calculation and mechanism

Abstract

The exploitation of effective modification means to get highly active and stable catalytic materials for heterogeneous photo-Fenton-like (HPF-like) process has been enormously stimulated by the globally increased demands for water purification. Oxygen vacancies (OVs) modulation is regarded as a prevalent strategy to improve the performance of heterogeneous catalysts. Herein, the polyvinylpyrrolidone (PVP) modified CuFeO2 (PVP/CFO) catalysts were prepared to degrade ofloxacin (OFX) target pollutant in HPF-like process. The modification of PVP introduced the rich OVs and more Fe2+ active sites on PVP/CFO surface, while the aggregation of CuFeO2 particles was inhibited by the modification of PVP. The PVP/CFO catalyst with the addition of 4 g PVP in the synthesis (PVP/CFO-4) possessed more superior catalytic performance for OFX degradation than other prepared catalysts in the present work. Additionally, the as-prepared PVP/CFO-4 catalyst possessed good stability for OFX degradation in HPF-like system. The introduced OVs by PVP modification and the generated photoelectron on PVP/CFO by light excitation effectively accelerated in-situ recycling of Cu2+/Cu+ and Fe3+/Fe2+, which was beneficial for •OH/•O2– formation and OFX mineralization. The quenching experiment and EPR spectra revealed that •OH, •O2- and e- were the major active species, and h+ was auxiliary species for OFX degradation. The OFX degradation pathways were proposed by density functional theory calculation and liquid chromatography mass spectrometry. The overall toxicity of intermediates was relieved after HPF-like degradation of OFX based on quantitative structure–activity relationship predictions.