High performance of the A-Mn2O3 nanocatalyst for persulfate activation: Degradation process of organic contaminants via singlet oxygen.

A-Mn 2 O 3 nanocatalyst possess efficient catalytic properties for PS activation and exhibits remarkable performance for the degradation of organic contaminants via singlet oxygen. In this study, the catalytic activation of persulfate (PS) via metal oxides was investigated, and the A-Mn 2 O 3 nanocatalyst was found to have the highest efficiency among other PS activators for the degradation of organic contaminants. Additionally, A-Mn 2 O 3 exhibited a remarkable efficiency in activating PS for the degradation of phenol compared to both B-Mn 2 O 3 and C-Mn 2 O 3. This was attributed to the longer bonds between edge-sharing MnO 6 octahedra, the unique structure, the high content surface –OH groups, and the average oxidation states. This indicated that all these properties played an important role in an efficient PS activation. Electron paramagnetic resonance (EPR) spectroscopy, scavenger tests, and chemical probes were conducted to investigate the reactive oxygen species (ROS). Singlet oxygen (1O 2) was determined to be the main ROS generated from PS activation. A plausible mechanism study was proposed, which involved inner-sphere interactions. An electron transfer of the Mn species facilitated the decomposition of PS to generate HO 2 • /O 2 • − radicals, which were utilized as a precursor for 1O 2 generation via direct oxidation or the recombination of HO 2 • /O 2 • −. Finally, the phenol and Sulfachloropyridazine (SCP) degradation pathways were proposed by 1O 2 over the A-Mn 2 O 3 /PS system according to HPLC and LC-MS results. [ABSTRACT FROM AUTHOR]