Oxygen vacancy induced peroxymonosulfate activation by Mg-doped Fe₂O₃ composites for advanced oxidation of organic pollutants

Abstract

Oxygen vacancy engineering has emerged as an effective approach to improve the performance of catalysts for peroxymonosulfate (PMS) activation. Herein, we report a facile precipitation method followed by calcination to synthesize cost-effective and environmentally friendly magnesium-doped hematite (Mg/Fe2O3) composites. Multiple characterization results reveal that the incorporation of Mg can significantly increase the oxygen vacancies and specific surface area of 5%Mg/Fe2O3, leading to a significantly enhanced performance in degrading Rhodamine B (RhB) through PMS activation. In a typical reaction, almost complete RhB (10 mg/L) removal can be achieved by the activation of PMS (0.2 g/L) using 5%Mg/Fe2O3 (0.5 g/L). Moreover, the as-synthesized catalyst exhibits a broad pH working range (3.96-10.69), high stability, and recyclability. The effects of several parameters (e.g., catalyst amount, PMS dosage, solution pH and temperature, and coexisting inorganic anions) on the removal of RhB in the 5%Mg/Fe2O3/PMS system are investigated. A plausible PMS activation mechanism is proposed, and 1O2 and O2- are identified as the predominant reactive species in RhB degradation instead of SO4- and OH. This study provides new insights into the development of highly efficient iron-based catalysts and highlights their potential applications in environmental purification.