Breaking Oxygen Dependency: Enhanced Micropollutant Degradation during Periodate-Based Catalysis under Deoxygenated Conditions

Abstract

The presence of organic micropollutants in water sources worldwide has highlighted the need for effective oxidation methods suitable for various specialized conditions. This study is the first to elucidate the mechanisms driving enhanced pollutant removal using a periodate (PI, IO₄^–)-mediated system under oxygen-limited conditions. A carbonaceous catalyst was employed to activate PI, exhibiting significantly improved micropollutant degradation (sulfadiazine, SDZ) in a deoxygenated environment, achieving a degradation rate seven times faster than under aerobic conditions. Fe(IV), O₂^•–, reactive intermediates, and electron transfer mechanisms were found to contribute to SDZ degradation, but they were not the factors behind the increased degradation efficiency under deoxygenated conditions. Crucially, the absence of oxygen enhanced degradation by eliminating competition with IO₄^– for electrons, strengthening PI adsorption, and stabilizing the Fe–O bond, which collectively promoted PI activation. Continuous bubbling further accelerated the degradation of SDZ throughout the experiment. Additionally, this system demonstrated broad-spectrum degradation capabilities, with the catalytic activity of CWBC (carbon-based catalyst prepared with coagulation waste) restored through simple methanol treatment and minimal interference from coexisting substances in water. Overall, this study advances the understanding of PI-based advanced oxidation processes under deoxygenated conditions, broadening their potential applications.