Development of a heterogenous catalyst FeWO4/Cu2S as peroxymonosulfate activator for effective sulfachloropyridazine elimination

This work successfully synthesized magnetic FeWO 4 /Cu 2 S through a facile method with efficient peroxymonosulfate (PMS) activation to eliminate sulfachloropyridazine (SCP) in water, in which 97.56% of SCP was removed in 30 min with activating only 0.2 mM PMS . Factors such as calcination temperature, the addition amount of WS 2 in FeWO 4 /Cu 2 S, molar ratio of Cu/Fe in FeWO 4 /Cu 2 S, catalyst dosage, solution pH, inorganic anions and natural organic matters（NOM）were investigated. It was found that in FeWO 4 /Cu 2 S at 1:2 possessed the best catalytic performance for PMS. FeWO 4 /Cu 2 S performed well in a wide pH range (3–9) and the effect was better under acidic conditions. A high catalyst dosage could supply more catalytic active sites for PMS activation and encourage the production of reactive oxygen species . Anions (HCO 3 − and HPO 4 2− ) and NOM significantly inhibited SCP degradation, whereas Cl − had only a tiny inhibitory impact. In addition, H 2 PO 4 − and NO 3 − demonstrated duality in the degradation of SCP. The oxidation process was dominated by non free radical oxidation by 1 O 2 rather than free radicals oxidation by HO⋅ and SO 4 •− . Three SCP degradation pathways—SO 2 extrusion, S-N bond cleavage and hydroxylation were proposed according to intermediate products analysis. The mechanism was found that the introduction of W improved the dual metals cycles of Fe 3+ /Fe 2+ and Cu + /Cu 2+ which could efficiently promote PMS activation. In addition, the magnetic FeWO 4 /Cu 2 S was easy to separate after reaction, which had great application potential in the water treatment .