Studies On Treatment Of Drinking Water By Nanometer Ag-TiO₂ Photocatalysis

Nano-semiconductor photocatalysis, as a promising advanced oxidization technology, has been a hot research issues in recent years. It is supposed to have important application in water treatment, environmental protection and medicine and health and so on. In this paper, nanometer Ag-TiO₂ film was prepared by sol-gel method and dip-coating process. The Ag-TiO₂ film photocatalyst was characterized by XRD,DRS,SEM and AFM. The influencing factors to eliminate bacterial growth factor (TOC, NO₂-N and T-P) and affact bactericidal action (microbial colony and coliform) under different photocatalytic conditions were compared. The mechanism of eliminating bacterial growth factors and bactericidal action were also discussed. The experimental results show as follows:1, The sol-gel method and dip-coating process were the good methods for preparing nanometer Ag-TiO₂ photocatalytic thin film. The crystal structure phase in the Ag-TiO₂ thin film was characterized as anatase phase with approximately 10 nanometer diameter of particle size by XRD and DRS. The absorption peak of Ag-TiO₂ thin film shifted to the visible range in the absorption spectrum, and the absorbance of Ag-TiO₂ thin film increased strongly in the UV or visible light range.2, In the experiments of eliminating bacterial growth factor by using nanostructure Ag-TiO₂ film photocatalyst, the photocatalytic activities of Ag-TiO₂ film for eliminating bacterial growth factor were higher than that of TiO₂ film by UV or visible light irradiation. The removal rate of TOC and NO₂-N attained more than 90% in 1h when the amount of doped Ag on TiO₂ film and aerating rate were controlled at 0.5%(w/w) and 0.5 L·min^-1, respectively. Althought Ag-TiO₂ film was used more than one times, the photocatalytic activity and the removal rate of TOC and NO₂-N still maintained at high lever. However, the eliminating T-P rate by using nanostructure Ag-TiO₂ film photocatalytic treatment was scarcely affected by some factors, perhaps, mechanism of T-P elimination was adsorption effect rather than photocatalytic decomposition。...