Photocatalytic breakdown of tetracycline via Z-scheme BiFeO3/Ag/Cr2O3 nanocomposite under visible light irradiation: Degradation mechanism, toxicity evaluation and antibacterial activity

Abstract

Antibiotics are being released into the environment due to their extensive use; thus, treating bacteria in aquatic environments that are resistant to antibiotics rapidly and effectively is serious. In this study, a Z-scheme BiFeO₃/Ag/Cr₂O₃ photocatalyst for tetracycline degradation was prepared using the hydrothermal method. The photodegradation efficiency of TC-HCl was 91.5% following a 90-min exposure to visible light. Additionally, the recyclability test confirmed the stability of the BiFeO₃/Ag/Cr₂O₃ nanocomposite during tetracycline photodegradation by achieving an 86% degrading efficiency after four cycles. According to the pseudo-first-order degradation, the rate constant of BiFeO₃/Ag/Cr₂O₃ was 0.089 min⁻¹ as compared to BiFeO₃/Ag (0.040 min⁻¹). Also, free radicals $•O_2^{-}$and •OH may accelerate antibiotic degradation, allowing for the development of helpful breakdown procedures. The ESR investigation revealed the presence of DMPO- •O₂Hand DMPO-•OH, with signals intensifying up to a visible exposure time of 08 minutes. Moreover, LC-MS spectrometry assisted in clarifying the TC photodegradation mechanisms. Interestingly, bacterial strains such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) growth suppression were assessed using the well diffusion method via BiFeO₃/Ag/Cr₂O₃ nanocomposite. Therefore, BiFeO₃/Ag/Cr₂O₃ nanocomposite is a promising candidate for toxicity assessments and wastewater treatment due to its long-term reliability and excellent degradation efficiency.