Singlet oxygen presenting a higher detoxification potential on enrofloxacin than sulfate and hydroxyl radicals

With the aid of radical and non-radical reactive species (RS), advanced oxidation processes can efficiently degrade emerging organic contaminants including antibiotics but may generate toxic transformation products (TPs). However, the detoxification capacity of popular RS has not been well elucidated. This study compared the detoxification of enrofloxacin (ENR) with three RS-dominated systems: ¹O₂, SO₄^•-+^•OH, ^•OH. The toxicity of ENR TPs generated from those systems was evaluated with multiple methods. It was found that the ¹O₂-dominated system detoxified ENR more effectively than the other systems in terms of microbial respiratory inhibition, developmental toxicity in zebrafish embryos, and three typical molecular biomarkers, including reactive oxygen species (ROS), and lactate dehydrogenase (LDH), and glutathione S-transferase (GST). Based on their chemical structures of ENR TPs projected with UPLC-QTOF-MS/MS, the toxicity prediction tool (T.E.S.T) revealed that the ¹O₂-dominated system led to more harmless TPs than the others. The results of this study underscore the great potential of ¹O₂-dominated system in the detoxification of organic contaminants.