Design and application of heterogeneous catalysts as peroxydisulfate activator for organics removal: An overview

Recently, redox oxidation technology based on peroxydisulfate (PDS) activation by heterogeneous catalyst has shown promising potential for environmental decontamination. The heterogeneous catalysts employed for PDS activation can be classified as metal-and carbon-based catalysts. Currently, the sustainability of metal-based catalysts as PDS activator is contentious due to metal leaching during application. Various strategies have been employed to address this issue, namely (1) optimizing the reaction conditions, (2) designing supported metal-based catalysts, and (3) developing metal-free (carbon) catalysts. This article reviews recent advancement in the development of metal-and carbon-based catalysts for PDS activation and provides critical discussion on the strategies to improve the robustness of these catalysts. Finally, potential future directions of the heterogeneous catalyst/PDS system are proposed to further improve the understanding and sustainability of the system. These include (1) developing Fe-0/PDS system operated under sequencing batch reactor mode, (2) establishing the relationship between type of pollutant and reusability of catalyst, (3) correlating the relationship between redox-active functional groups and mechanism of reaction, (4) integrating the heterogeneous catalyst/PDS system with other processes, and (5) application of the system with real industrial and secondary effluents at pilot scale level.