Efficient activation of peroxymonosulfate on cobalt hydroxychloride nanoplates through hydrogen bond for degradation of tetrabromobisphenol A

Abstract

Heterogeneous activation of peroxymonosulfate (PMS) using cobalt-based nanomaterials is a promising strategy to degrade organic pollutants, in which the formation of Co(II)OH complex is a critical step. Here, cobalt hydroxychloride (Co2(OH)3Cl) nanoplates were synthesized by a one-pot precipitation method and exhibited high activity for the degradation of tetrabromobisphenol A (TBBPA) in the presence of PMS. The use of Co2(OH)3Cl and PMS caused a complete TBBPA degradation (40 mg L−1) at pH 9 in 2 min. The pseudo-first-order rate constant of TBBPA is 2.5 min−1, being 9, 14, and 6 folds larger than those for α-Co(OH)2, β-Co(OH)2, and Co3O4 as catalysts, respectively. The dissolved Co2+ (0.15 mg L−1) corresponds to 0.24% of the total cobalt in Co2(OH)3Cl and has negligible influence on the TBPPA degradation. Co2(OH)3Cl shows long-term stability (longer than 9 months) with the high activity after the oxidation treatment. The high activity of Co2(OH)3Cl attributes to the Cl− enhanced reactivity of surface Co(II)OH. The coordinated Cl− not only enhances the ability of surface Co(II)OH for anchoring both HSO5− and SO52− through the intermolecular hydrogen bond, but also improves electron transfer between Co(II) and PMS, leading to efficient generation of singlet oxygen for the TBPPA degradation.