Hollow and oval-configured ultrafine Co 3 O 4 as a highly-efficient activator of monopersulfate for catalytic elimination of Azorubin S

Azorubin S (ARS) represents one of the most common and frequently-utilized toxic azo dyes produced from industrial activities. While various conventional treatment techniques could not effectively eliminate ARS from water, heterogeneous metal-based catalyst coupled with monopersulfate (MPS) is a highly-efficient process for eliminating ARS, in which tricobalt tetroxide (Co 3 O 4 ) has been attracted increasing attention as a preeminent MPS activator due to its outstanding physicochemical properties. However, the nanoscale Co 3 O 4 particles usually pose a limitation of serious agglomeration in the aqueous environment, thus lowering their efficiency. Thus, developing an easy-synthesized and exceptionally efficient Co 3 O 4 -based catalyst is crucially paramount. Therefore, in this work, a special hollow-structured oval-like cobalt oxide (abbreviated as HOCO) was successfully constructed using Co-metal organic framework as a precursor, which was then utilized for catalyzing activation of MPS to degrade ARS. This as-obtained HOCO exhibited distinct physicochemical characteristics from commercially-available Co 3 O 4 , which subsequently resulted in superior activities for MPS activation in ARS degradation. Specifically, 100% of ARS could be degraded in 30 min with a corresponding reaction kinetic of 0.22 min − 1 by HOCO + MPS system. SO 4 •– radicals were validated to be primary reactive species for ARS degradation while the degradation pathway of ARS was also elucidated. This study further provides insightful information about the development of novel hollow-structured Co 3 O 4 -based catalyst for catalyzing activation of MPS to remove toxic dyes from water.