Peroxydisulfate activation by magnetic nanoflakes zero-valent iron/graphitized carbon composites for norfloxacin removal: Synergistic effect of ¹O₂ with surface Fe(IV)

The recycling and utilization of waste biomass resources have attracted widespread attention due to their enormous potential economic value. In this study, a magnetic zero-valent iron nanoflake-modified graphitic mesoporous carbon composite (Fe@SBCx) was prepared using ultrasound-assisted impregnation and pyrolysis strategies, and employed as an efficient peroxydisulfate (PDS) activator for the removal of the antibiotic norfloxacin (NOR) from water. The Fe@SBC1.13/PDS system exhibited excellent oxidation performance, achieving nearly complete removal (>99 %) of 10 mg/L NOR within 25 min. Singlet oxygen (O-1(2)) and ferryl iron species (Fe(IV)) were identified as the major oxidative reactive species in the system. The formation of electron donor-acceptor complexes during the reaction facilitated the decomposition of PDS and the generation of oxidative species. Fe@SBC1.13 demonstrated satisfactory recyclability and catalytic stability. Based on density functional theory (DFT) calculations and intermediate product analysis, the degradation pathways of NOR were proposed. Moreover, the toxicity evaluation results revealed a lower bacterial cytotoxicity in the treated drainage. Overall, this study not only enriches the theoretical research on the degradation mechanisms of fluoroquinolone antibiotics in the environment but also provides a viable approach for developing highly efficient and carbon-neutral catalysts.