Evaluation of MnO2-templated iron oxide-coated diatomites for their catalytic performance in heterogeneous photo Fenton-like system.

Herein, iron oxide-coated diatomites were prepared through hydrothermal synthesis and sacrificial template redox etching reaction. The microstructure characterization results revealed that the Fe2O3 nanorods were uniformly distributed on the surface of diatomite. The effects of diverse synthetic parameters on morphology of as-synthesized Fe2O3@diatomite were investigated. When the reaction time was prolonged from 12h to 24h, the morphology of FeOOH would change from nanorods into nanoflowers. Two different crystal phases of Fe2O3@diatomite were obtained from the FeOOH@diatomite samples calcined under different atmospheres. The catalytic activity of α-Fe2O3@diatomite was evaluated by the heterogeneous photo Fenton-like system through degradation of methylene blue (MB, 10 - 40mgL-1) in the presence of hydrogen peroxide (H2O2, 9mM - 120mM) under UV light irradiation. It was found that α-Fe2O3@diatomite composites showed very excellent degradation efficiency, which was about 99% within 120min under UV irradiation. This catalyst extended the range of pH values of homogeneous Fenton reaction, in which the MB removal rate was maintained over 80.8%. Moreover, the α-Fe2O3@diatomite catalyst still showed sound reusability after 5 rounds of degradation of MB dye. In principles, a possible photo-catalytic mechanism was proposed to testify metal oxides composites for heterogeneous photo Fenton-like reaction.