ZrO2 modified MnO2 catalysts for efficient peroxydisulfate activation and wide pH-range pollutant removal

Abstract

Maintaining the stability and efficiency of pollutant degradation across a wide pH range remains a critical challenge for the practical application of advanced oxidation processes (AOPs). In this study, a heterogeneous catalyst was developed by integrating acidic-active ZrO₂ with multivalent MnO_x to activate persulfate for the efficient degradation of a typical dye, Acid Orange II. Benefiting from the amphoteric nature of ZrO₂, the reaction environment maintains pH stability under varying conditions, thereby preventing changes in the surface charge state of the catalyst caused by pH fluctuations. The ZrO₂/MnO₂ composite exhibited excellent performance over a broad pH range (3–9), along with a significantly reduced manganese leaching ratio. Moreover, the presence of ZrO₂ promoted the formation of oxygen vacancies, enhancing the activity of manganese species and thereby improving the catalytic performance and reusability of the composite. The acidic microenvironment provided by ZrO₂ facilitated the generation and activity of sulfate radicals (SO₄˙⁻), resulting in a markedly improved total organic carbon (TOC) removal efficiency. This work presents a pH-adaptive catalytic system for persulfate activation through microenvironmental modulation, demonstrating promising potential for practical applications in AOP-based water treatment.