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

The exploitation of effective modification means to get highly active and stable catalytic materials for hetero-geneous photo-Fenton-like (HPF-like) process has been enormously stimulated by the globally increased de-mands 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 center dot OH/center dot O2- formation and OFX mineralization. The quenching experiment and EPR spectra revealed that center dot OH, center dot 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.

Automated summary

The development of highly active and stable catalytic materials for heterogeneous photo-Fenton-like (HPF-like) process has gained significant attention due to the increasing demands for water purification worldwide. Oxygen vacancies (OVs) modulation is a prevalent strategy to enhance the performance of heterogeneous catalysts. In this study, polyvinylpyrrolidone (PVP) modified CuFeO2 (PVP/CFO) catalysts were prepared for the degradation of ofloxacin (OFX) in HPF-like process. The introduction of PVP resulted in rich OVs and more Fe2+ active sites on PVP/CFO surface, while inhibiting the aggregation of CuFeO2 particles. The PVP/CFO-4 catalyst with 4 g of PVP showed superior catalytic performance for OFX degradation and good stability in the HPF-like system. The introduced OVs and photoelectron generated on PVP/CFO effectively accelerated the in situ recycling of Cu2+/Cu+ and Fe3+/Fe2+, promoting the formation of center dot OH/center dot O2- and OFX mineralization. The primary active species for OFX degradation were identified as center dot OH, center dot O2-, and e-, with h+ serving as an auxiliary species. Density functional theory calculation and liquid chromatography mass spectrometry were used to propose the OFX degradation pathways, and the overall toxicity of intermediates was reduced after HPF-like degradation based on quantitative structure-activity relationship predictions.