Natural magnetic pyrrhotite as a high-Efficient persulfate activator for micropollutants degradation: Radicals identification and toxicity evaluation

Abstract

This study discusses the SO4− based process mediated by natural magnetic pyrrhotite (NP) for the degradation of refractory organic micropollutants. Complete degradation of 20 μM phenol in distilled water (DW) was obtained within 20 min using NP/PS (persulfate) system. Electron paramagnetic resonance spectra indicated aerobic and acidic conditions favored the generation of both SO4− and OH species, but only OH signal was survived at alkaline condition. The leaked Fe2+ and Fe(II) of NP collectively work to activate PS and generate surface and bulk SO4− and OH simultaneously. The identified intermediates indicate the transformation of benzene ring is the key step for phenol degradation by NP/PS system. Moreover, phenol degradation was greatly inhibited in surface water (SW, 29%) and wastewater (WW, 1%), but 25.9% and 17.5% of TOC removal were obtained in the SW and WW during NP/PS treatment, respectively. Additionally, the acute toxicity tests for NP/PS process exhibited a fluctuating trend depending on the water matrix, while the genotoxic activity analysis indicated that the treated phenol solutions were not genotoxic but cytotoxic. Overall, this study provides a solution to abate refractory organic micropollutants in water systems.