Preparation And Performance Of Silica Gel Supported TiO₂

Photocatalytic technology possesses many merits such as strong oxidation power, low cost, high efficiency, easy operation, innocuity, no secondary pollution and etc., which suggests its promising application. Nano titanium dioxide is well known as a cheap, chemical stability, large-band gap semiconductor with photocatalytic activity attached much attention of the researchers. At present, the core point in this technology is to develop new nanosized TiO₂, which is Vis-light responsive, possesses high quantum yield and is of lower cost. In order to improve the photocatalystic ability of the TiO₂, titanium dioxide was modified by metal oxide depositing, metal ion doping and precious metal depositing.In this paper, TiO₂-SiO₂ composites catalyst was prepared. Methyl blue was chosen as the representative of organic pollutants to investigate the photocatalytic activity of the as-prepared TiO2-SiO₂ composites. XRD, BET, UV-Vis and AFM were employed in the influence analysis of TiO₂-SiO₂ composites catalyst.1,TiO₂-SiO₂ composite catalysts were prepared by hydrothermal of cheap Ti(SO₄)₂. These composites were charactered by BET, XRD measurements. The photocatalytic activity of the catalysts was investigated by photodegrading the target pollutants of Methyl blue (MB). The TiO₂-SiO₂ composite catalysts show much better photocatalytic activity than that of pure TiO₂. Among of these catalysts, the 5h-70%Ti composite catalysts shows best photocatalytic activity, its rate constant attach to 0.0307 min^-1, almost two times then the pure TiO₂. Although the rate constant of P-25 is higher than the 5h-70%Ti composite catalysts, the UV-Vis spectras of Methylene blue(MB) solution which was irradiated by UV light in the presence of catalysts for 60 min showed no absorption by 5h-70%Ti composite catalysts and higher absorption by P-25 from 200 to 400 nm.2,Studied the influence of the solvent in synthesis TiO₂-SiO₂ composite catalysts used sol-gel method. Make the titanium alkoxides dissolved in various alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-hexanol). Photocatalytic experiments showed that the samples calcinated at 700℃displayed the best photocatalytic activity, the rate constants of w-700, b-700, h-700 and P-25 was 0.0594 min^-1, 0.0828 min^-1, 0.0886 min^-1, 0.0461 min^-1 respectively. The results showed that the crystallite size, the pore size and crystallinity have been influenced by alcohols. In general, when increased the number of carbon atoms in the alcohols, the crystallite size and pore size were all increased.3,TiO₂ films were prepared used chitosan as additive. These films were charactered by XRD and AFM measurements.