Removal of Antibiotic Florfenicol by Sulfide-Modified Nanoscale Zero-Valent Iron

Florfenicol (FF, C 12 H 14 Cl 2 FNO 4 S), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zerovalent iron (S-nZVI). Sulfidized nZVI (62.5 m 2 g –1 ) that was prepared using a one-step method resulted in small Fe 0 /Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m 2 g –1 ). No obvious removal of FF was observed by unsulfidized nZVI. S-nZVI degraded FF, having a surface area normalized reaction rate constant of 3.1 × 10 –4 L m –2 min –1 . The effects of the S/Fe molar ratio, initial FF concentration, initial pH, temperature, and water composition on the removal of FF by S-nZVI, and on the formation of reaction products, were systematically investigated. Both dechlorination and defluorination were observed, resulting in four degradation products (C 12 H 15 ClFNO 4 S, C 12 H 16 FNO 4 S, C 12 H 17 NO 4 S, and C 12 H 17 NO 5 S). High removal efficiencies of FF by S-nZVI were achieved in groundwater, river water, seawater, and wastewater. The reactivity of S-nZVI was relatively unaffected by the presence of both dissolved ions and organic matter in the waters tested.