Efficient Degradation of 2,4-Dichlorophenol on Activation of Peroxymonosulfate Mediated by MnO2

Sulfate radical based-advanced oxidation process has received increasing interest in the remediation of wastewater and contaminated soil. In this study, degradation of 2, 4-dichlorophenol (2, 4-DCP) was investigated over peroxymonosulfate (PMS) activation by MnO 2 , which was prepared by liquid-phase oxidation method. The prepared MnO 2 was characterized by transition electron microscopy, X-ray diffraction, N 2 adsorption–desorption, and X-ray photoelectron spectroscopy. Characterization results showed that α-MnO 2 exhibited the highest surface area and Mn (III) content. The PMS activation by MnO 2 in 2, 4-DCP degradation followed the order of α-MnO 2  >  γ-MnO 2  > β-MnO 2 , which is dependent on the properties of MnO 2 including crystal structure, surface area and Mn (III) content. Influences of initial concentration of 2, 4-DCP, PMS and MnO 2 dosage, pH and co-existing inorganic ions on the degradation were examined. Electron paramagnetic resonance (EPR) and quenching experiments with ethanol and tert-butanol suggested that sulfate radicals were the dominant radicals in the process. Findings in this study indicated that α-MnO 2 was an attractive catalyst for activation of PMS to degrade 2, 4-DCP in aqueous solution.