Author(s): Azarmidokht Hosseinnia, Mansoor KeyanpourRad, Mohammad Pazouki
Single phase anatase titania powders with size below 20 nm and surface area of 75 m /g were 2 synthesized by a simple precipitation method at pH 5 and dehydration of agglomerates by azeotropic distillation. The powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area, after calcinations at 550°C for 3 hrs. This nanoparticles was used for photocatalytic degradation of various dyes with different chromophores such as triphenyl methane (Methyl violet), heteropolyaromatic dyes (Methylene blue, Rhodamine B), azoic dyes (Methyl red, Methyl orange) and hydroquinone dye (Sudan blue II B) under visible-light irradiation. The effect of catalyst loading and concentrations of the dyes on the rate of degradation was investigated. In order to mask the ultraviolet (UV) radiation of sun light partially, the photocatalytic reactions were done in Pyrex glass reactors. These photooxidation reactions gave similar results when 500 W white halogen lamp was used as the light source. A mechanism for the photoassisted degradation of the dyes mediated by TiO nanoparticles under visible light 2 radiation is proposed.