Synthesis and Characterization of Rectorite/ZnO/TiO2 Composites and Their Properties of Adsorption and Photocatalysis for the Removal of Methylene Blue Dye

As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites (REC/ZnO/TiO2) were synthesized and characterized in this study. Effects of experimental parameters including TiO2 mass ratio, solution pH and catalyst dosage on the removal of methyl blue (MB) were also conducted. The presence of a little mass ratio (2%-6%) of TiO2 highly promoted the photoactivity of REC/ZnO/TiO2 in removal of MB dye from aqueous solution, in which ZnO and REC played a role of photocatalyst and adsorbent. The promotion effects of TiO2 may result from the accelerated separation of electron-hole on ZnO. The observed kinetic constant for the degradation of MB over REC/ZnO and REC/ZnO/TiO2 were 0.015 and 0.038 min(-1), respectively. The degradation kinetics of MB dye, which followed the Langmuir-Hinshelwood model, had a reaction constant of 0.17 mg/(L.min). The decrease of removal ratio of MB after five repetitive experiments was small, indicating REC/ZnO/TiO2 has great potential as an effective and stable catalyst.