Magnetic Nanoscaled Fe3O4/CeO2 Composite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of 4-Chlorophenol

Abstract

Magnetic nanoscaled Fe₃O₄/CeO₂ composite was prepared by the impregnation method and characterized as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation. The catalytic activity was evaluated in view of the effects of various processes, pH value, catalyst addition, hydrogen peroxide (H₂O₂) concentration, and temperature, and the pseudo-first-order kinetic constant of 0.11 min^–1 was obtained for 4-CP degradation at 30 °C and pH 3.0 with 30 mM H₂O₂, 2.0 g L^–1 Fe₃O₄/CeO₂, and 0.78 mM 4-CP. The high utilization efficiency of H₂O₂, calculated as 79.2%, showed a promising application of the catalyst in the oxidative degradation of organic pollutants. The reusability of Fe₃O₄/CeO₂ composite was also investigated after six successive runs. On the basis of the results of metal leaching, the effects of radical scavengers, intermediates determination, and X-ray photoelectron spectroscopic (XPS) analysis, the dissolution of Fe₃O₄ facilitated by CeO₂ played a significant role, and 4-CP was decomposed mainly by the attack of hydroxyl radicals (•OH), including surface-bound •OH_ads generated by the reaction of Fe²⁺ and Ce³⁺ species with H₂O₂ on the catalyst surface, and •OH_free in the bulk solution mainly attributed to the leaching of Fe.