Novel α-MnO2/AC catalysts for heterogeneous catalytic ozonation process to remove BAA in dye wastewater

Abstract

Designing catalysts that are both efficient and resistant to interference poses a significant challenge in the field of catalytic ozone oxidation. In this study, four composite nanomaterials with different crystalline phase structures of MnO₂ and its loading onto activated carbon were synthesized by hydrothermal synthesis-calcination method and successfully used to catalyze the degradation of BAA by ozonation. The synthesized α-MnO₂/AC showed excellent performance and stability, and the degradation rate of 100 mg/L BAA could reach 96.27 % within 40 min under optimal conditions. Compared with MnO₂ alone, α-MnO₂/AC possessed lower polarization resistance, faster charge transfer rate, and higher Mn³⁺ and oxygen vacancy contents. Through the mechanistic study of Heterogeneous catalytic ozonation (HCO), it was confirmed that Mn(III) and oxygen vacancies together acted as active sites to enable O₃ adsorption and activation to generate ROS, and OH and ¹O₂ reacted with BAA as the main ROS in this system. In addition, a potential pathway for the degradation of BAA by HCO was proposed and evaluated for its toxicity. This study provides a new strategy and understanding for designing manganese dioxide composite catalysts with different crystalline phases and the mechanistic exploration of the HCO pathway.