Phenol Removal Performance and Mechanism Using Catalytic Ozonation with the Catalyst of Cobalt-doped -MnO₂

In this paper, Cobalt-doped alpha-MnO2 (i.e., Co-alpha-MnO2) were synthesized through hydrothermal method. Phenol was employed as targeted pollutants to investigate the catalytic ozonation performance of Co-alpha-MnO2. Results showed that Co-alpha-MnO2 significantly improved the phenol removal increased to 97.47 % after 40 min, which was 16.46 %, 38.92 % higher than that of alpha-MnO2 catalytic ozonation and single ozonation without catalyst. Additionally, the physicochemical properties of alpha-MnO2 and Co-alpha-MnO2 were analyzed using technologies such as XRD, TEM, BET and XPS. Compared to alpha-MnO2, Co-alpha-MnO2 has larger specific surface area (79.496 m(2)/g) and pore volume (0.0396 cm(3)/g), higher Mn3+ relative content (41.16 %) and adsorbed oxygen content (18.99 %). Also, the oxygen vacancy content, lattice defect content and surface hydroxyl content of Co-alpha-MnO2 are higher than that of alpha-MnO2, which could result in higher catalytic oxidation performance of Co-alpha-MnO2. The influence of masking agent showed that surface hydroxyl group, similar to OH and similar to O-2(-) were involved in the catalytic ozonation of phenol. This study could help recognize the role of surface hydroxyl groups and active free radicals and demonstrate the contribution of reactive oxygen species on phenol removal in Co-a-MnO2 systems.