Spatial confinement-regulated peroxymonosulfate activation to boost the generation of high-valent cobalt and radical species for achieving rapid removal of organic pollutants

It is of great significance to establish simple and effective methods to tackle water pollution problems. Herein, Co-loaded hollow carbon sphere (namely Co-HCS-1) served as PMS activation mediator was synthesized. The construction of hollow structure can improve specific surface areas and offer more active sites, thereby reducing electron transfer resistance and increasing contact among PMS, pollutant and catalyst. Hence, the Co-HCS-1-mediated direct electron-transfer oxidation between PMS and pollutant was enhanced. After embedding Co-based catalyst in the shell of hollow carbon sphere, hollow carbon shell will provide spatial confinement for Co-based catalyst, which shortened mass transfer process. Thus, spatial confinement effect originating from carbon sphere can accelerate the charge transfer between PMS and active sites of Co-HCS-1, thereby promoting O-O bond cleavage of PMS. As a result, the generations of radicals and high-valent metal complexes (namely Co-HCS-1≡Co4+) were boosted. Under the combined effects of electron-transfer oxidation, reactive oxygen species and Co-HCS-1≡Co4+, more than 90 % of typical organic pollutants can be removed from simulated wastewater within 5 min by Co-HCS-1/PMS system, and a high removal efficiency of total organic carbon can also be realized. To sum up, current work provided a valuable reference for the preparation and application of catalyst with high activity in PMS activation.