Ceramic Glazing to Enhance Stability and Selectivity of CoAl₂O₄ Catalyst for Wastewater Advanced Oxidation

Catalytic membranes for persulfate-based advanced oxidation processes (AOPs) are gaining prominence in wastewater treatment due to their high reactivity and application potential. However, their real-world deployment faces two key limitations: (i) catalyst deactivation from leaching and site poisoning in harsh reactive conditions and (ii) nonselective oxidation causing excessive oxidant use due to background organic matter interference. To address these challenges, we developed a glazed CoAl₂O₄ spinel catalyst with an amorphous surface through high-temperature quenching. This amorphized surface structure eliminates grain boundaries, significantly enhancing resistance to oxidative degradation and minimizing cobalt catalyst leaching (∼20 ppb). More importantly, the glazed surface interface promotes a nonradical electron-transfer mechanism from pollutants to persulfate, enabling selective degradation of persistent micropollutants such as 1,4-dioxane. Structural characterization and electrochemical analysis reveal that the amorphous interface introduces abundant oxygen vacancies and suppresses radical generation, supporting direct pollutant-to-oxidant electron transfer. Membrane tests confirm high flux operation, excellent pollutant selectivity, and long-term stability, positioning this catalyst as a next-generation platform for selective, stable, and sustainable AOP-based water treatment.