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

High activation capacity of porous CeO 2 is demonstrated in persulfate-driven advanced oxidation processes (PS-AOPs) for organic pollutant degradation. Herein, porous CeO 2 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 CeO 2 /PDS system, a non-covalent complex [≡Ce(IV)–O–H‧‧‧S 2 O 8 2 − ]* was formed, and the high proportion of Ce(Ⅳ) facilitated a 1 O 2 -mediated nonradical pathway for norfloxacin (NOR) degradation. Conversely, the formation of a covalent complex [≡Ce(III)–O–O–SO 3 − ]* in the CeO 2 /PMS system initiated a radical pathway involving surface-bonded SO 4 •− /•OH. However, strong electrostatic repulsion between CeO 2 (+) —NOR +,0 limited the accessibility of these surface-bonded radicals, greatly reducing oxidant utilization efficiency. Consequently, porous CeO 2 exhibited a notably higher activation capacity (17.2 times) for PDS compared to PMS. This study introduces an efficient strategy for developing high-performance CeO 2 catalysts and provides novel insights into the application of Ce-based catalysts in PS-AOPs. • A porous CeO2 with hierarchical macrostructure and abundant micro/mesopores is developed. • The porous CeO2 demonstrated superior activation capacity for PDS compared to PMS. • A nonradical pathway of 1O2-mediated oxidation is driven by the non-covalent complex in PDS system. • A radical pathway involving surface-bonded SO4•− and •OH is activated by the covalent complex. • Electrostatic repulsion hinders the accessibility of surface-bonded SO4•− and •OH in PMS system.