In situ fabrication of a novel S-scheme heterojunction photocatalyts Bi2O3/P-C3N4 to enhance levofloxacin removal from water

Abstract

The removal of antibiotics from water by S-scheme heterojunction photocatalytic materials has become a research hotspot in recent years. Herein, an S -scheme heterojunction Bi2O3/P-C3N4 composite photocatalytic material was prepared via in situ thermal polymerization and the degradation effect and internal mechanism of levofloxacin (LVFX) were explored under simulated sunlight. The results show that the Bi2O3/P-C3N4 composite photocatalytic material can remove 89.2% of the LVFX in water within 75 min under simulated sunlight, which is greatly improved compared to the original Bi2O3 and P-C3N4. The degradation effect is improved because the constructed S-scheme system helps spatially separate the electrons with higher reducing abilities generated by P-C3N4 and the holes with higher oxidizing ability generated by Bi2O3; moreover, BET specific surface area and the hydrophilicity is improved. Further through radicals capture, electron spin resonance (ESR), the density functional theory (DFT) experiments verified the mechanism of S-scheme heterojunction degradation of LVFX and revealed that holes and superoxide free radicals are the main active substances in the degradation of LVFX. Finally, liquid chromatography–tandem mass spectrometry (LC–MS) was used to determine the intermediate products in the degradation path, and the LVFX degradation pathway was proposed. This study provides a new insight into the degradation of LVFX and provides support for antibiotic removal of photocatalytic materials in real water environments.