Activation of persulfate by magnetic MnFe₂O₄-bentonite for catalytic degradation of 2,4-dichlorophenol in aqueous solutions

Abstract

Magnetic MnFe₂O₄-bentonite was synthesized by chemical co-precipitation method(CCM) and applied as catalyst in heterogeneous activation of persulfate(PS) to oxidize a target pollutant, 2,4-dichlorophenol(2,4-DCP), in aqueous solutions. The surface morphology and structure of MnFe₂O₄-bentonite were characterized by X-ray diffraction( XRD), scanning electron microscope(SEM), energy dispersive X-ray(EDX) and X-ray photoelectron spectroscopy(XPS) analyses.The catalytic activity of MnFe₂O₄-bentonite for 2,4-DCP degradation was evaluated considering the effects of various process parameters, such as mass ratio of MnFe₂O₄ to bentonite, concentration of catalyst, PS concentration, and pH. The MnFe₂O₄-bentonite hybrid exhibited higher catalytic activity than pure MnFe₂O₄. Treatment with 5 g/L MnFe₂O₄-bentonite at 30 °C for 240 min oxidized 92% of 100 mg/L 2,4-DCP(70.2% mineralization), whereas treatment with pure MnFe₂O₄ under the same condition oxidized only 70% of the pollutant. This result indicate the enhanced performance of the activated PS. Moreover, MnFe₂O₄-bentonite exhibits stable performance with minimal loss in activity after five successive runs. Thus, MnFe₂O₄-bentonite could be a promising catalyst in oxidative degradation of 2,4-DCP.