Enhanced efficiency of refractory organic pollutant degradation over a wide pH range by peroxymonosulfate activated by cobalt-doped FeS

A series of cobalt-doped FeS (x% Co-FeS) nanoparticles, prepared via a hydrothermal method, were introduced as catalysts for generating radicals from peroxymonosulfate (PMS) to degrade the endocrine disrupter bisphenol S (BPS) in wastewater. The kinetic results revealed that only a small amount of Co doping (7% At.) could greatly improve the efficiency of PMS activation by FeS, leading to the rapid degradation of BPS (0.21min(-1) vs. 0.0046 min(-1)), and no secondary pollution caused by Co leaching. Notably, exceptional activation was observed over a wide pH range from 4 to 11. Moreover, various background ions (NO3, Cl, CO32) and temperatures (10.0-55.0 degrees C) minimally affected BPS degradation, suggesting excellent applicability in different sewage environments. Furthermore, quenching experiments, coupled with electron paramagnetic resonance technology, identified singlet oxygen (O-1(2)) and sulfate radicals (SO4 center dot-) as the primary reactive oxygen species responsible for BPS degradation. Due to the selectivity of O-1(2) and the high redox potential of SO4 center dot-, this technology had excellent anti-interference and degradation ability. In six repeated batch experiments, the catalysts showed favorable cyclability and stability due to Co(II)/Co(III) cycling mediated by structural S2-. These results provided insights into the potential applications of modifying natural FeS-type minerals as a promising heterogeneous catalyst for environmental restoration.