Synthesis of cubic Mn2O3 and its catalytic performance in activating peroxymonosulfate for degradation of MB

In this study, uniform Mn2O3 cubic with a size of 0.6–1.1 µm was prepared using a simple carbonate precipitation-calcination method, and its performance in activating peroxymonosulfate (PMS) for degradation of methylene blue (MB) was investigated. A single factor experiment was conducted to investigate the degradation of MB by taking process parameters as variables, such as catalyst amount, PMS dosage, initial MB concentration, reaction temperature and co-existed anions. The results showed that a MB degradation rate of 81.49% was achieved within 50 min under the reaction conditions: Mn2O3 amount of 0.1 g/L, PMS dosage of 0.6 mmol/L, MB concentration of 10 mg/L, a total volume of 500 mL and reaction temperature of 25 °C. In addition, it was found that the introduction of C2O42- or PO43- had a negative effect on MB degradation, with inhibition ratio reaching 33.08% and 17.47%, respectively. However, Cl- had no inhibitory effect on MB degradation. Furthermore, reactive species in the system of Mn2O3/PMS were identified by electron paramagnetic resonance (EPR) tests, and results showed that •OH, SO4•-, •O2– and 1O2 all participated in the MB degradation process. Moreover, Mn2O3 exhibited stable catalytic performance during four consecutive cycling runs, indicating that the as-prepared cubic Mn2O3 is expected to be a potential catalyst for PMS activation and dye wastewater treatment.