Catalytic Ozonation of Quinoline by Prepared Fe-α-MnO2 and Ce-α-MnO2: The Role of Surface Hydroxyls and Oxygen Vacancies

Abstract

Quinoline, as one of the typical toxic and refractory organic pollutants in coal chemical industry wastewater, poses a significant threat to human health and environmental quality. In this study, MnCexOy and MnFexOy catalysts were successfully synthesized by doping Ce3+ and Fe2+ into α-MnO2 at a molar ratio of 1∶10 and were applied to the process of catalytic ozonation for the degradation of quinoline. Additionally, a variety of characterization techniques were employed to elucidate the characteristics of the catalysts, including scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy, H2-TPR, NH3-TPD. The results show that, in the catalytic ozonation system for quinoline removal, MnCexOy demonstrates excellent quinoline removal efficiency of 87.45%, which is higher than that of MnFexOy (78.83%) and unmodified α-MnO2 (62.67%). By introducing the surface hydroxyl masking agent HPO42−, the significant role of surface hydroxyl groups and oxygen vacancies in the catalytic degradation of quinoline by MnCexOy was further demonstrated. Exploring the surface characteristics of catalysts is beneficial for continued understanding of the active centers of catalysts. Research results will be helpful to the deep treatment and reuse of tailing water of coking wastewater.