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 MnO2, which was prepared by liquid-phase oxidation method. The prepared MnO2 was characterized by transition electron microscopy, X-ray diffraction, N2 adsorption-desorption, and X-ray photoelectron spectroscopy. Characterization results showed that α-MnO2 exhibited the highest surface area and Mn (III) content. The PMS activation by MnO2 in 2, 4-DCP degradation followed the order of α-MnO2 >  γ-MnO2 > β-MnO2, which is dependent on the properties of MnO2 including crystal structure, surface area and Mn (III) content. Influences of initial concentration of 2, 4-DCP, PMS and MnO2 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-MnO2 was an attractive catalyst for activation of PMS to degrade 2, 4-DCP in aqueous solution.