Magnetic core-shell-structured Fe 3 O 4 @CeO 2 as an efficient catalyst for catalytic wet peroxide oxidation of benzoic acid.

A magnetic core-shell-structured Fe 3 O 4 @CeO 2 catalyst was prepared by a simple solvothermal method and applied in the solid state for catalytic wet peroxide oxidation (CWPO) of benzoic acid. The obtained catalyst was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), magnetic measurements, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that Fe 3 O 4 @CeO 2 possessed superior catalytic efficiency for CWPO of benzoic acid than that of Fe 3 O 4 . The high catalytic activity was caused by a synergistic effect between Fe 3 O 4 and CeO 2 , which assisted the decomposition of H 2 O 2 into hydroxyl radicals (·OH). Fe 3 O 4 @CeO 2 exhibited low Fe leaching of 4.2 mg L -1 , which approximately accounted for barely 0.76% of the total Fe amount in the catalyst. The effects of radical scavengers indicated that benzoic acid was degraded mainly by ·OH attack, which occurred both in the bulk solution and on the Fe 3 O 4 @CeO 2 surface. In the stability tests, there was loss of merely 4% in the benzoic acid removal rate after six cycles of reaction, and the saturation magnetization of Fe 3 O 4 @CeO 2 hardly changed, which suggested that the Fe 3 O 4 @CeO 2 catalyst was fairly effective in reutilization and stability.