Synthesis of Rectorite/Fe3O4/ZnO Composites and Their Application for the Removal of Methylene Blue Dye

A novel series of rectorite-based magnetic zinc oxide (ZnO) photocatalysts (REC/Fe3O4/ZnO) was synthesized and characterized in the present work. The fabricated REC/Fe3O4/ZnO composite possessed a high specific surface area and high capacity of adsorption and photocatalysis toward methylene blue (MB) dye. The adsorption isotherm of the dye on the composite fitted well to the Langmuir model, with a maximum adsorption of 35.1 mg/g. The high adsorption capacity increased the interactions between the dye and the REC/Fe3O4/ZnO, which enabled efficient decomposition of the dye under simulated solar radiation using REC/Fe3O4/ZnO as the photocatalyst. The degradation kinetics of MB dye followed the Langmuir-Hinshelwood model. More importantly, the degradation of MB dye and the mass loss of REC/Fe3O4/ZnO after three repetitive experiments were quite small. This suggests that the magnetic composite has great potential as an effective, stable, and easily recovered catalyst. Four major intermediates were detected during the degradation of MB dye and the degradation pathway was proposed.