Anaerobic degradation and defluorination of the polyfluorinated pharmaceutical fluoxetine by sulfidated nanoscale zerovalent iron

Fluoxetine (FLX) is a widely used pharmaceutical that enters the environment through wastewater treatment plant effluents and land application of biosolids. FLX is a per- and polyfluorinated alky substance (PFAS) and is of environmental concern because of its toxicity. Current FLX treatment strategies yield persistent fluorinated products (e.g., trifluoroacetate) or rely on costly catalysts that hinder field-scale implementation. Herein, we demonstrate the capacity of sulfidated nanoscale zerovalent iron (S-nZVI), a less costly reductant, to defluorinate the perfluorinated moiety in FLX. Degradation of FLX by S-nZVI under anaerobic conditions was evaluated in microcosms at different sulfidation doses at 25 °C to determine the most reactive S-nZVI composition. S-nZVI [S/Fe]=0.28 provided the highest reactivity to FLX, and twostage particle dosing at 38 °C yielded complete degradation of FLX (8 mg/L) and 87% defluorination. Degradation involved sorption and C-O cleavage to phenylpropan-1-1amine and 4-(trifluoromethyl) phenol, followed by formation of defluorinated aromatic compounds. In sludge, S-nZVI 0.28 increased FLX defluorination and degradation by up to 7.5-fold compared with sludge alone, but reactions were slower. Overall, S-nZVI can eliminate C-F bonds that contribute to persistence of FLX and its natural transformation products in both water and wastewater sludge, although reactivity varies with environmental matrices.