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

In this paper, for the first time the spinel sulfide carrollite (CuCo 2 S 4 ) was applied to activate peroxymonosulfate (PMS) for the abatement of an endocrine disrupting compound (EDC) bisphenol S (BPS) in water. The hydrothermally synthesized CuCo 2 S 4 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 (SO 4 − ) 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 SO 4 − ; 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, CuCo 2 S 4 has higher catalytic effect per surface cobalt atom than the counterpart oxides for PMS activation, probably due to the lower electronegativity of S 2− than O 2− . CuCo 2 S 4 could be a potentially useful catalyst for water/wastewater treatment.