Favorable recycling photocatalyst TiO2/CFA: Effects of loading percent of TiO2 on the structural property and photocatalytic activity

A series of photocatalysts TiO2/CFA were prepared using coal fly ash (CFA), waste discharged from coal-fired power plant, as substrate, and then these photocatalysts were characterized by scanning electron microscope, X-ray diffraction analysis, nitrogen adsorption test and ultraviolet-visible absorption analysis. The effects of loading percent of TiO2 on the photocatalytic activity and re-use property of TiO2/CFA were evaluated by the photocatalytic decoloration and mineralization of methyl orange solution. The results show that the pore volume and the specific surface area of the TiO2/CFA both increased with the increase in the loading percent of TiO2, which improved the photocatalytic activity of TiO2/CFA. However, when the loading percent of TiO2 was too high (up to 54.51%), superfluous TiO2 was easy to break away from CFA in the course of water treatment, which was disadvantaged to the recycling property of TiO2/CFA. In this study, the optimal loading percent of TiO2 was 49.97%, and the efficiencies of photocatalytic decoloration and mineralization could be maintained above 99% and 90%, respectively, when the photocatalyst was used repeatedly, without any decline, even at the sixth cycle.