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In this work, we proposed to synthesize CuFe2O4/Fe2O3 core-shell materials with different Fe2O3 contents in order to create new and efficient photo-Fenton-like catalysts for the degradation of methylene blue with oxalic acid as a radical-producing source. The catalysts were prepared through two stages: first, CuFe2O4 was prepared by a hydroxide coprecipitation – annealing method and then, Fe2O3 was immobilized on CuFe2O4 surface by a simple impregnation – annealing procedure. According to the experimental results, our CuFe2O4/Fe2O3 core-shell materials exhibit high photo-Fenton-like catalytic activity for the degradation of methylene blue under both UVA light and visible light, as well as good ferromagnetic properties, which allows them to be easily separated from the solution by a magnet. Among them, the catalyst prepared with the molar CuFe2O4/Fe2O3 ratio of 1:2 showed the best catalytic performance with the rate constant of 2.103 h–1 under UVA light and 0.542 h–1 under visible light, which were 2 times higher than CuFe2O4 sample. The enhanced catalytic activities of our core-shell materials can be attributed to the high content of surface Fe3+ species, high specific surface area and the presence of rod-like Fe2O3 particles on their surface.

In this work, we proposed to immobilize Fe2O3 nanoparticles on the surface of magnetic CuFe2O4 particles by a facile impregnation – annealing method at different annealing temperatures (200, 300, 400 and 500°C) in order to create new heterogeneous photo-Fenton catalysts with enhanced catalytic performance for the oxidation of organic dyes. The influences of annealing temperatures used in the synthesis procedure on the phase composition, the morphology, the particle size and the surface functional groups of our catalysts were investigated by XRD, FE-SEM and FTIR techniques, respectively. The photo-Fenton catalytic performance was evaluated by the degradation of methylene blue under both UVA and visible light illumination in the presence of H2C2O4 as radical-producing source. According to the experimental results, Fe2O3 nanoparticles were successfully coated on CuFe2O4 surface, which successfully formed the α-Fe2O3 phase in the phase composition and also increased the Fe3+ content on the surface. As a consequence, the rate constant of photo-Fenton catalytic degradation of methylene blue over these samples were clearly improved. More especially, owing to the good magnetic property of CuFe2O4 component, our CuFe2O4/Fe2O3 samples were easy to be separated from the solution by a magnet, making them more feasible in practical applications of environmental treatment. Among our catalytic samples, the CuFe2O4/Fe2O3 sample annealed at 300°C showed the best performance with the highest rate constants under both UVA light and visible light. Its catalytic activities was found to be 6.8 times higher than CuFe2O4 under UVA light and 2.1 times higher than CuFe2O4 under visible light. However, when the annealing temperature was up to 500°C, the catalytic activity was reduced, which can be explained by the growth of particles and the stabilization of surface Fe-O bonds.