Favorable recycling photocatalyst TiO ₂ /CFA: Effects of loading percent of TiO ₂ on the structural property and photocatalytic activity

A series of photocatalysts TiO ₂ /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 TiO ₂ on the photocatalytic activity and re-use property of TiO ₂ /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 TiO ₂ /CFA both increased with the increase in the loading percent of TiO ₂ , which improved the photocatalytic activity of TiO ₂ /CFA. However, when the loading percent of TiO ₂ was too high (up to 54.51%), superfluous TiO ₂ was easy to break away from CFA in the course of water treatment, which was disadvantaged to the recycling property of TiO ₂ /CFA. In this study, the optimal loading percent of TiO ₂ 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.