Preparation And Photocatalystic Properties Of N And Ag Doped TiO₂

Single-doped and co-doped TiO2 with various amounts of silver and nitrogen have been prepared by the sol-gel using tetrabutyl titanate, silver and nitrogen as raw materials. The photodegradation ability to methyl orange solution with using various amounts and different calcination temperatures of TiO2 was studied by some techniques of XRD and others. Then the best shape TiO2 was used on the experimental of degradation of different organic compounds, to make sure that how to exploit the best photodegradation ability of TiO2.The photocatalytic activities to methyl orange of single-doped and co-doped TiO2 were all higher than pure TiO2. The photocatalytic activities were highest when the proportion of N-doped was N:TiO2=4:1 and Ag-doped was Ag:TiO2=0.02:1.The two degradation rates of single-doped catalysts were more 36% and 42% than pure TiO2 separately. But the photocatalytic activities of co-doped TiO2 (molar ratio TiO2:N:Ag=1:4:0.02) was higher than single-doped. Each of the degradation rates was:pure TiO2 was 40%, N-doped was 75%, Ag-doped was 70% and co-doped was 84%. It proved that the mechanisms of metal-doped and non-metal-doped affected together in co-doped. The phase transformation of every kind TiO2 which was prepared under different temperatures was as:The rutile peak of TiO2 and TiO2/N appeared at 500℃, and the peak of TiO2/N was weaker. The rutile peak of TiO2/Ag and TiO2/N-Ag appeared at 600℃. These phenomena show that both N and Ag could control the phase transformation, and the effect of control of silver was higher than nitrogen.The photocatalytic degradations of different organic matter experiment were conducted under different conditions by use the best shape of TiO2/N-Ag to be sure that how the catalyst could exert its best catalytic under the best conditions, and made the study on the relationship of removal rate of COD and decolorization rate of the organic solution. The results show that the best conditions of cresol red were:temperature of solution was 35℃, pH=5, initial concentration of cresol red was 10mg/L, the concentration of catalyst was 1g/L. The decoloration rate was 100% after 160mins which was irradiated by visible-light, the removal rate of COD was 86% under the UV-light; the best conditions of bromophenol blue were most like cresol red except the pH, its best pH was 8. The decoloration rate was 100% by use 150mins, removal rate of COD was 89%; the best pH of methyl red was 4. The decoloration rate was 100% by use 170mins, removal rate of COD was 82%; the best pH of cochineal red was 6. The decoloration rate was 100% by use 160mins, removal rate of COD was 86%.