Reactive oxygen species and NOM-induced surface rejection guarantee effective removal of dye pollutants by cobalt-manganese bimetallic oxide loaded ceramic membrane activating peroxydisulfate

Abstract

Developing high-efficient, environmental-friendly, stable catalytic membrane is of great significance for the removal of organic pollutants from natural water. Herein, the aim of this study was to fabricate ceramic membranes loaded with cobalt-manganese bimetallic oxides (Co–Mn-M) and evaluate their effectiveness and reaction mechanisms in activating peroxydisulfate (PDS) to degrade organic pollutants. The result showed that Co–Mn-M not only had exceptional effect on dye removal (91.36 %) through PDS activation, but also exhibited synergistic efficacy in mitigating membrane irreversible fouling during filtration. The superiority of the Co–Mn-M/PDS system could be attributed to two reasons. On the one hand, dual redox cycles of Co3+/Co2+ and Mn2+/Mn3+/Mn4+ and oxygen vacancy on membrane surface ensured the continuous activation of PDS to generate abundant reactive oxygen species including SO4•-, •OH, O2•-, and 1O2, among which SO4•- played a predominant contributor to dye degradation. On the other hand, the hydroxylation and carboxylation via radical oxidation could increase the energy barrier for natural organic matter (NOM) adhering to the membrane surface, thereby achieving a NOM-induced surface rejection for contaminants. Consequently, the Co–Mn-M/PDS system showed lesser energy consumption than conventional ceramic membrane filtration. In conclusion, this study presented a promising strategy for dye removal, ensuring the safe reclamation of water resources.