Preparation of Fe3O4/α-MnO2 Magnetic Nanocomposites for Degradation of 2,4-DCP through Persulfate Activation

In this study, Fe3O4 magnetic nanoparticles (MNPs) were loaded on α-MnO2 nanowires using an improved hydrothermal synthesis method combined with an ultrasonic coprecipitation method, the loading ratio was optimized, the efficiency of the prepared Fe3O4/α-MnO2-activated persulfate (PS) system for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated, and the effects of PS concentration, Fe3O4/α-MnO2 magnetic nanocomposites (MNCs) dosage, pH value and initial pollutant concentration on the degradation of 2,4-DCP were investigated. The results showed that when the initial concentrations of 2,4-DCP, PS, and Fe3O4/α-MnO2 MNCs were 100 mg/L, 30 mmol/L, and 0.4 g/L, the degradation rate of 2,4-DCP reached 96.3% after 180 min of reaction at 30 °C under a neutral condition, and the fitting results showed that the degradation of 2,4-DCP by the Fe3O4/α-MnO2-activated PS system conformed to quasi-first-order kinetics. The degradation of 2,4-DCP by different Fe3O4/α-MnO2-activated PS systems was compared, and a possible PS activation mechanism was proposed. The Fe3O4/α-MnO2 MNCs exhibited excellent reusability, and by introducing Fe3O4/α-MnO2 MNCs as the PS activator into the advanced oxidation process (AOP) system, the electron transfer of Mn(III/IV) and Fe(III/II) on the surface of MNCs was realized, thus greatly improving the reaction efficiency.