Preparation and Characterization of Buoyant Nitrogen-doped TiO2 Composites Supported by Fly Ash Cenospheres for Photocatalytic Applications

Fly ash cenospheres (FACs) coated with nitrogen-doped TiO2 (N-TiO2) composites were prepared by the sol-gel method for use as photocatalysts. The photocatalytic activity and kinetics of the composites produced at different calcination temperatures and with different nitrogen doping contents were studied under visible light irradiation by monitoring the environmental degradation of methylene blue (MB). The MB degradation ratio of N-TiO2/FAC (25%, 450 °C) was 10% higher than that of N-TiO2 and 40% higher than that of TiO2/FAC. These N-TiO2/FAC composites floated in water and could be recovered after the photocatalytic reaction by phase separation.