Highly efficient activation of porous CeO2 for peroxydisulfate outperforming peroxymonosulfate: Kinetic behavior and mechanism study

Abstract

High activation capacity of porous CeO2 is demonstrated in persulfate-driven advanced oxidation processes (PS-AOPs) for organic pollutant degradation. Herein, porous CeO2 with abundant active sites was synthesized using a self-template method, followed by an investigation of its catalytic activity and mechanism in PMS/PDS-driven systems. In the CeO2/PDS system, a non-covalent complex [≡Ce(IV)–O–H‧‧‧S2O82−]* was formed, and the high proportion of Ce(Ⅳ) facilitated a 1O2-mediated nonradical pathway for norfloxacin (NOR) degradation. Conversely, the formation of a covalent complex [≡Ce(III)–O–O–SO3−]* in the CeO2/PMS system initiated a radical pathway involving surface-bonded SO4•−/•OH. However, strong electrostatic repulsion between CeO2(+)—NOR+,0 limited the accessibility of these surface-bonded radicals, greatly reducing oxidant utilization efficiency. Consequently, porous CeO2 exhibited a notably higher activation capacity (17.2 times) for PDS compared to PMS. This study introduces an efficient strategy for developing high-performance CeO2 catalysts and provides novel insights into the application of Ce-based catalysts in PS-AOPs.