Enhanced permanganate oxidation of phenolic pollutants by alumina and potential industrial application

In this study, we found that alumina (Al₂O₃) may improve the degradation of phenolic pollutants by KMnO₄ oxidation. In KMnO₄/Al₂O₃ system, the removal efficiency of 2,4-Dibromophenol (2,4-DBP) was increased by 26.5%, and the apparent activation energy was decreased from 44.5 kJ/mol to 30.9 kJ/mol. The mechanism of Al₂O₃-catalytic was elucidated by electrochemical processes, X-ray photoelectron spectroscopy (XPS) characterization and theoretical analysis that the oxidation potential of MnO₄^- was improved from 0.46 V to 0.49 V. The improvement was attributed to the formation of coordination bonds between the O atoms in MnO₄^- and the empty P orbitals of the Al atoms in Al₂O₃ crystal leading to the even-more electron deficient state of MnO₄^-. The excellent reusability of Al₂O₃, the good performance on degradation of 2,4-DBP in real water, the satisfactory degradation of fixed-bed reactor, and the enhanced removal of 6 other phenolic pollutants demonstrated that the KMnO₄/Al₂O₃ system has satisfactory potential industrial application value. This study offers evidence for the improvement of highly-efficient MnO₄^- oxidation systems.