A superior active and stable spinel sulfide for catalytic peroxymonosulfate oxidation of bisphenol S

Abstract In this paper, for the first time the spinel sulfide carrollite (CuCo2S4) was applied to activate peroxymonosulfate (PMS) for the abatement of an endocrine disrupting compound (EDC) bisphenol S (BPS) in water. The hydrothermally synthesized CuCo2S4 outperformed conventional cobalt and copper oxides/sulfides in both catalytic activity and stability (i.e. metal leaching) in this oxidation process. The spinel sulfide was most active under neutral pH conditions, which is preferred for water/wastewater treatment. Sulfate radicals (SO4 −) which was proved to be the prominent oxidant species in this oxidation process, attacked on BPS producing multiple hydroxylated degradation intermediates. Cu(II)/Cu(I) and Co(III)/Co(II) synergetic surface redox couples are found responsible for the catalytic activation of PMS producing SO4 −; furthermore, the thermodynamically favorable reaction between surface Cu(I) and surface Co(III) guarantees the electron transfer between the surface metal sites. As confirmed by turnover frequency calculation, CuCo2S4 has higher catalytic effect per surface cobalt atom than the counterpart oxides for PMS activation, probably due to the lower electronegativity of S2− than O2−. CuCo2S4 could be a potentially useful catalyst for water/wastewater treatment.