Heterogeneous activation of peroxymonosulfate by flower-like cobalt sulfide enhanced sulfamethoxazole degradation via non-radical pathways

Abstract

The treatment of emerging pollutants has become a challenging and multidisciplinary subject. Advanced oxidation processes based on persulfate are a strategic opportunity to address this issue, with research into catalysts and catalytic processes being the focus of this process. In this work, flower-like cobalt sulfide (F-CoS) particles acted as catalysts in peroxymonosulfate (PMS) activation for degrading an organic pollutant, sulfamethoxazole (SMX). The results indicated that F-CoS/PMS combined system performed excellently, with SMX being completely oxidized within 10 min. And the system exhibited superior resistance to environmental factors (e.g. pH and anions). Radicals quenching and electron paramagnetic resonance (EPR) analyses indicated that non-radical pathways based on high-valent cobalt-oxo (Co(IV)) species and 1O2 take a dominant position in SMX degradation, instead of SO4•− and •OH. Electrochemical, in-situ Raman and density functional theory (DFT) calculations revealed that PMS interacts with Co sites on the F-CoS surface, and then electronic transfer processes occurred, in which PMS acts as an electron acceptor to produce Co(IV) species and as an electron donor to produce 1O2. This study not only implies a method with great potential application in organic wastewater treatment but also contributes to further comprehending the heterogeneous activation process and catalytic mechanism of PMS.