Magnetically Separable and Durable MnFe2O4 for Efficient Catalytic Ozonation of Organic Pollutants

Abstract

Magnetically separable MnFe2O4 was prepared successfully by a sol–gel combustion method. The synthesized MnFe2O4 was characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, zeta potential, and magnetic hysteresis loops. The catalytic activity of MnFe2O4 was evaluated by the ozonation of 4-chlorophenol (4-CP) at different solution pH value, ozone gas concentration, MnFe2O4 dosage, and initial 4-CP concentration. The ozone consumption was monitored and the ·OH exposure was calculated in different processes. It was found that MnFe2O4 was highly effective in catalyzing ozone decomposition and favored to generate more hydroxyl radicals. Moreover, the synergistically catalytic effect between Mn and Fe in MnFe2O4 was confirmed. Finally, lifetime of MnFe2O4 was measured in a novel integrated membrane-heterogeneous catalytic ozonation reactor designed for the first time. All the experimental results show that MnFe2O4 is a highly recoverable, efficient, and durable catalyst in the ozonation.