Pathways, toxicity assessment, and mechanism study of Gatifloxacin photodegradation on Au-Black-TiO2 nanorod arrays system through theoretical calculations and experiments

Antibiotics have garnered significant interests because of their harmful effects on non-target aquatic organisms, photocatalysis is an important technique for their removal. However, the photodegradation pathways, the toxicity of intermediates and the photodegradation mechanism of antibiotics are still unclear. In this study, Gatifloxacin was picked as the antibiotics’ representative via theoretical calculations and experiments to gain a comprehensive understanding of its decomposition pathways, the toxicity of intermediates, and the photodegradation mechanism on the Au-Black-TiO 2 nanorod arrays system. The highest photodegradation rate of Gatifloxacin is up to 92.6 %, with a reaction rate constant value of 0.00437. Moreover, three potential photodegradation pathways for Gatifloxacin were proposed based on density functional theory (DFT) and LC-MS experiments. Additionally, the toxicity of intermediates produced during the photodegradation of Gatifloxacin was assessed using quantitative structure-activity relationship (QSAR), revealing a decreased level of toxicity. Furthermore, the superior photodegradation mechanism and possible charger transfer pathways were also investigated. In conclusion, this research suggests a potential approach to understand the pathways, toxicity assessment, and mechanism insight during the antibiotics’ photodegradation process.