Oxidation towards enrofloxacin degradation over nanoscale zero-valent copper: Mechanism and products

Abstract

Enrofloxacin (ENR) is a widely used veterinary fluoroquinolone antibiotic and is frequently detected in water environments. The degradation of ENR was examined utilizing molecular oxygen mediation using nanometer zero-valent copper (nZVC) as the catalyst in this work. The dosage of nZVC, initial pH, and reaction temperature were investigated as contributing factors to ENR degradation. The reactive oxygen species (ROS) that participated in the reaction were identified, their generation mechanisms were elucidated, and the effects on ENR degradation were assessed. More emphasis was given to exploring ENR degradation and transformation pathways via analyses of HPLC-TOF-MS. Data showed that at 35 ℃, with an initial pH of 3 and exposed to air, an nZVC dose of 0.5 g·L− 1 degraded ENR by 99.51% dramatically. HO• radicals were identified as the dominant ROS, and conversions among Cu0, Cu+, and Cu2+ played crucial roles in the generation of ROS. The destruction mechanism of ENR was speculated based on analyses of HPLC-TOF-MS results as the transformation of the piperazine ring into an oxidized state with a -COOH substitution with HO•, which caused ENR to be mineralized and converted into CO2, H2O, and \({\text{NO}}_{\text{3}}^{\text{-}}\). This research proposes a capable and practical method for removing ENR from water.