Structure of a novel Co-based heterogeneous catalyst via Mn3(PO4)2 as a carrier to efficiently activate peroxymonosulfate for improving degradation of sulfonamides.

Effective degradation of sulfonamides (SAs) in water is of global importance for decreasing its pathogenicity and bioaccumulation. In this study, Mn3(PO4)2 was used as a carrier to fabricate a novel and high-efficient catalyst with Co3O4 anchored (Co3O4@Mn3(PO4)2) for the activation of peroxymonosulfate (PMS) to degrade SAs. Surprisingly, the catalyst exhibited superior performance, and nearly 100% of SAs (10 mg L-1) including sulfamethazine (SMZ), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and sulfisoxazole (SIZ) was degraded by Co3O4@Mn3(PO4)2-activated PMS within 10 min. A series of characterization of the Co3O4@Mn3(PO4)2 composite were conducted and the main operational parameters of SMZ degradation were investigated. SO4•-, •OH, and 1O2 were determined to be the dominating reactive oxygen species (ROS) responsible for the degradation of SMZ. Co3O4@Mn3(PO4)2 also exhibited excellent stability and the removal rate of SMZ still maintained over 99% even in the fifth cycle. The plausible pathways and mechanisms of SMZ degradation in the system of Co3O4@Mn3(PO4)2/PMS were deduced on the basis of the analyses of LCMS/MS and XPS. This is the first report on high-efficient heterogeneous activating PMS by mooring Co3O4 on Mn3(PO4)2 to degrade SAs, which provides us with a strategy to structure novel bimetallic catalysts for PMS activation.