Preparation, catalytic efficiency and mechanism of Fe3O4/HNTs heterogeneous Fenton-like catalyst

In situ anchor of Fe3O4 nanoparticles (NPs) onto the external surface of natural halloysite nanotubes (HNTs) was achieved by a simple one-pot solvothermal method. The Fe3O4/HNTs composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and N2 adsorption-desorption. Characterization results showed that the magnetic Fe3O4 NPs formed tightly on the external surface of HNTs with good dispersion. Fe3O4/HNTs composites exhibited typical ferromagnetic property determined by VSM tests and could be recovered by an external magnet. Degradation experiments were conducted using the active dye RhB as the target probe to evaluate the Fenton-like catalytic efficiency of Fe3O4/HNTs composites obtained under different preparation conditions. The experimental results indicated that the degradation efficiency of RhB could reach more than 98 % within 10 min reaction time, when the initial pH was 3.5, initial RhB concentration was 100 mg L−1, H2O2 concentration was 1.96 mmol L−1, and catalyst dosage was 0.5 g L−1, realizing the rapid degradation of high concentration dye. Comparative investigations revealed that the Fenton-like catalytic efficiency of Fe3O4/HNTs for degrading high concentration RhB was much higher than that of Fe3O4 NPs. The heterogeneous Fenton-like catalytic mechanism of Fe3O4/HNTs was elucidated. Hydroxyl radicals (•OH) and superoxides radicals (•O2-) dominated the RhB degradation in the Fe3O4/HNTs-H2O2 system.