Abstract
Carbon-coated TiO2 photocatalysts were prepared by a simple heat treatment of powder mixtures of anatase-type TiO2 (ST-01) with poly (vinyl alcohol) at 700 and 900°C in a N2 gas flow. The diffuse optical reflectance spectra of carbon-coated TiO2 showed on absorption edge for the anatase-type structure with a clear overlap with the absorption edge caused by carbon coated over the whole range of wavelengths used. These carbon-coated anatase photocatalysts had a relatively large apparent BET (Brunauer-Emmett-Teller) surface area, from 50 to 170m2·g-1, which suggests the formation of porous carbon layers, and showed a relatively high adsorptivity for various pollutants, e.g., methylene blue, reactive black-5, phenol and iminoctadine triacetate in water. The photocatalytic activity of the carbon-coated anatase thus prepared was evaluated by determinating rate constant for the decomposition of different pollutants in water. Rate constant was strongly dependent on the type of pollutant, but its dependence on the crystallinity of anatase phase, which was characterized by behavior the full width at half maximum intensity of its 101 X-ray diffraction line, was different, however, its tendency was similar. The relationsips between adsorptivity and rate constant for the four pollutants looked similar, and the pollutants adsorbed in the large amount was decomposed at a higher rate.
