Recent advances in cobalt-activated sulfate radical-based advanced oxidation processes for water remediation: A review.

Sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted increasing attention for the degradation of organic contaminants in water. The oxidants of SR-AOPs could be activated to generate different kinds of reactive oxygen species (ROS, e.g., hydroxyl radicals (OH), sulfate radicals (SO), singlet oxygen (O), and superoxide radicals (O)) by various catalysts. As one of the promising catalysts, cobalt-based catalysts have been extensively investigated in catalytic activity and stability during water remediation. This article mainly summarizes recent advances in preparation and applications of cobalt-based catalysts on peroxydisulfate (PDS)/peroxymonosulfate (PMS) activation since 2016. The review covers the development of homogeneous cobalt ions, cobalt oxides, supported cobalt composites, and cobalt-based mixed metal oxides for PDS/PMS activation, especially for the latest nanocomposites such as cobalt-based metal-organic frameworks and single-atom catalysts. This article also discussed the activation mechanisms and the influencing factors of different cobalt-based catalysts for activating PDS/PMS. Finally, the future perspectives on the challenges and applications of cobalt-based catalysts are presented at the end of this paper.