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

Florfenicol (FF, C12H14Cl2FNO4S), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zerovalent iron (S-nZVI). Sulfidized nZVI (62.5 m2 g–1) that was prepared using a one-step method resulted in small Fe0/Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m2 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 (C12H15ClFNO4S, C12H16FNO4S, C12H17NO4S, and C12H17NO5S). 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.