Non-radical activation of peroxymonosulfate with oxygen vacancy-rich amorphous MnOX for removing sulfamethoxazole in water

Abstract

Non-radical activation of peroxymonosulfate (PMS) is a promising technology for removing refractory organic pollutants. However, improving its efficiency is still a challenge due to its ambiguous mechanism. In this work, amorphous MnOX was synthesized through the hydrothermal reaction between KMnO4 and carbon nanopowder. The characterization results indicate that the hydrothermal temperature had little effect on the structure of the products but affected their surface composition. The sample prepared at 180 °C (MnOX-180) had rich oxygen vacancies and exhibited high activity for sulfamethoxazole (SMX) degradation with PMS. More than 97% of SMX was removed within 30 min by 0.5 g L−1 of MnOX-180 and 1 mmol L−1 of PMS at pH0 = 6.5. Activated PMS adsorbed on catalyst surface and singlet oxygen (1O2) produced from the non-radical pathway were the active species. Surface Mn4+ and oxygen vacancies were found to be responsible for the generation of activated PMS and 1O2, respectively. The degradation efficiency of SMX by MnOX-180 increased with decreasing solution pH, which can be attributed to the enhanced productionof activated PMS under acidic conditions. The water matrix had little effect on the performance of MnOX-180 due to the non-radical activation mechanism, suggesting its practical application in real water treatment.