In Situ Simultaneous Generation and Activation of Hydrogen Peroxide by the ZVI-Mn Catalyst for the Degradation of Enrofloxacin

Abstract

Fenton oxidation is highly efficient for removing pollutants from wastewater. However, the low utilization efficiency of oxidants increases operating costs and limits their application in water treatment. To address these issues, this study designed a novel Fenton-like catalyst: zerovalent iron/amorphous manganese composites (ZVI-Mn). This catalyst can activate O₂ in situ to generate H₂O₂ and simultaneously activate H₂O₂ to produce free radicals, achieving a 96.3% removal efficiency of enrofloxacin (ENR) from water. Radical quenching experiments showed that superoxide radicals (•O^2–) (46%) play a dominant role in ENR removal, while hydroxyl radicals (•OH) (28.2%) and singlet oxygen (¹O₂) (25.8%) also participate. Liquid chromatography–mass spectrometry (LC–MS), density functional theory (DFT) calculations, and toxicity estimations demonstrated effective ENR degradation and significant toxicity reduction of the intermediates, primarily through decarboxylation and ring opening. Additionally, ZVI-Mn achieved a 90.1% removal efficiency of ENR in aquaculture wastewater. This study proposes a new Fenton oxidation technique based on the in situ generation of H₂O₂, providing a meaningful research basis for environmentally friendly water treatment technologies.