Highly Efficient Florfenicol Removal via Nitrogen-Doped Zero-Valent Iron/Carbon Composites Activated with Peroxodisulfate: Mechanisms and Pathways
Abstract
Florfenicol (FF) accumulation in aquatic environments is a critical concern due to ecosystem disruption, microbial resistance, and health risks. While zero-valent iron (ZVI) is recognized for antibiotic remediation, studies on FF removal using nitrogen-doped ZVI-based materials activated by peroxodisulfate (PDS) and their degradation mechanisms are limited. This study synthesizes N-doped ZVI/C-1 via pyrolysis of iron-based metal-organic frameworks (MOFs), where organic ligands form a carbon matrix supporting ZVI particles and incorporate nitrogen atoms. The resulting N-doped ZVI/C-1 exhibits increased defect density, higher specific surface area, and improved hydrophobicity compared to ZVI/C. Electrochemical analyses further reveal that N-doped ZVI/C-1 possesses superior corrosion resistance, faster charge transport, and reduced hydrogen evolution activity. Consequently, N-doped ZVI/C-1 achieves a high FF removal efficiency of 96.0% within 30 minutes when activated by PDS. Mechanistic investigations indicate that the dominant degradation involves the generation of •OH and •SO4⁻ radicals, resulting in higher dechlorination and defluorination capacities compared to ZVI/C. Identified degradation pathways include C-Cl and C-F bond cleavage, C=O addition, and benzene ring decomposition, leading to a gradual reduction in FF toxicity. This study presents a promising strategy for FF removal and enhances the understanding of degradation mechanisms utilizing nitrogen-doped ZVI-based materials.