Tetracycline sensitizes TiO2 for visible light photocatalytic degradation via ligand-to-metal charge transfer

Treatment of antibiotics contaminated water remains a global environmental challenge. In this study, tetracycline (TC) was found to effectively sensitize pure TiO₂ for visible light photocatalytic degradation via a ligand-to-metal charge transfer mechanism. The sensitization was attributed to the formation of TC-TiO₂ complex and the overlap of the molecular orbitals of TC and the conduction band of TiO₂. The intermediate degradation products of TC, however, did not sensitize TiO₂, which was the reason for the low mineralization rate. Nevertheless, our results showed that the intermediate degradation products of TC had significantly reduced bactericidal effects and less induction of antibiotic-resistance genes (ARGs). This study showcases an effective treatment of antibiotics-containing wastewater using the most common photocatalyst TiO₂ with reduced risk in the spread of ARGs.