Fe–Mn/MCM-41: Preparation, Characterization, and Catalytic Activity for Methyl Orange in the Process of Heterogeneous Fenton Reaction

Active Fe- and Mn-loaded MCM-41 (Fe–Mn/MCM-41), which was synthesized via a hydrothermal reaction followed by impregnation, is used in the heterogeneous Fenton reaction to degrade methyl orange (MO) in aqueous solution. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption isotherm analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Compared with Fe/MCM-41 and Mn/MCM-41, Fe–Mn/MCM-41 showed higher activity for MO degradation and mineralization. Effects of various operating parameters, such as pH, Mn content, and H2O2 dosage, on the degradation process were subsequently investigated. Results of experiments on the effect of radical scavengers revealed that the degradation of MO could be attributed to oxidation by HO·. The synergy of Fe and Mn species in the Fenton oxidation process was also explained.