The enhanced peroxymonosulfate-assisted photocatalytic degradation of tetracycline under visible light by g-C3N4/Na-BiVO4 heterojunction catalyst and its mechanism

Abstract In this study, to enhance the peroxymonosulfate (PMS)-assisted photocatalytic degradation of tetracycline (TC) under visible light over BiVO4, g-C3N4 coupling and Na+ doping was used to co-modify BiVO4 to obtain g-C3N4/Na-BiVO4 (CN/Na-BiVO4) heterojunction catalyst. The prepared CN/Na-BiVO4 exhibited the apparently enhanced PMS-assisted photocatalytic TC degradation efficiency and can degrade approximately 98.20% of TC in 40 min, being 3.13 folds of BiVO4. The boosted TC degradation over CN/Na-BiVO4 was ascribed to the Z-scheme heterojunction formation, doped Na+, more V4+ and oxygen vacancies resulting from Na+ doping facilitate the electron-hole pairs migration and separation. Meanwhile, more V4+ and oxygen vacancies generated in Na-BiVO4 also promoted the PMS activation. Therefore, a large number of reactive oxygen species (ROSs), including •O2−, h+, •OH, SO4•−, and 1O2, were produced in CN/Na-BiVO4+PMS+Vis system to degrade TC. The mechanism of enhanced PMS-assisted photocatalytic degradation of TC was proposed. This work further highlighted the advantages of the PMS-assisted photocatalytic technology in antibiotics removal and also demonstrated that g-C3N4 coupling and Na doping co-modify BiVO4 was one effective and feasible method for promoting the PMS-assisted photocatalytic degradation of TC under visible light.