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

This study discusses the SO4 - based process mediated by natural magnetic pyrrhotite (NP) for the degradation of refractory organic micropollutants. Complete degradation of 20μM phenol in distilled water (DW) was obtained within 20min 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.