Unveiling the reaction pathways in the degradation mechanism of enrofloxacin by hydroxyl radicals: A DFT and experiment study

Fluoroquinolone antibiotics, widely used in daily life, contribute to environmental pollution due to their persistence in natural ecosystems. However, the degradation mechanism of fluoroquinolones remains elusive, which not only hinders the understanding of their environmental behavior but also restricts the development of effective remediations. This study investigates the degradation mechanism of enrofloxacin (ENR) through hydroxyl radicals (•OH), integrating density functional theory (DFT) calculations and experimental validations. The degradation process involves key steps such as bond activation (C–F, C–H, C–C) and decarboxylation, with the C–F bond and decarboxylation identified as rate-limiting steps. Experimental results confirm the theoretical predictions of degradation pathways and major by-products. Toxicity analysis shows that most degradation products exhibit significantly reduced toxicity compared to ENR. This work provides valuable insights into the degradation behavior of fluoroquinolones and lays the groundwork for designing advanced environmental remediation strategies. © 2025 Elsevier B.V.