The Research On Application Of New Co-doped TiO₂ In The Treatment Of Paper Wastewater

At present, nano-TiO2 photocatalyst is a good photocatalysis material. It has been applied to water, air purification and the destruction of bacteria and viruses. A large number of researchers focus their attention on it with regard to environmental pollution. However, it has some problems. The wave band for light absorption mainly focused on the rage of ultraviolet radiation, while it is out of work in the visible light region. Recombining rate of electron and hole in the semiconductor is high and quantum efficiency is low. It is difficult to be widely used in practice. In order to enhance the photocatalytic efficiency of TiO2 in the visible light region, tetrabutyl titanate was as precursors and sol-gel method was applied in this study to make TiO2, TiO2 mixed with F-Zn and La-B. Also XRD, UV-Vis and SEM analysis on specimen were carried out. By using xenon lamp of 500W as light resource (simulate sunlight). Methyl orange (40mg/L) solution which is to simulate dye wastewater as the goal degradation production, the photocatalysis performance of specimen were investigated under different mixture ratio and sintering temperature. In addition, the application of TiO2 photocatalytie oxidation technology in disposal of paper wastewater was researched, the results indicate:(1) The photocatalysis degradation rate of TiO2 specimen modified by adding F, Zn are enhanced in different degree. Especially, F(0.5%)/Zn(1.0%)/TiO2 sintered under the temperature of 500℃presents best photocatalysis activity and the degradation rate of degrading methyl orange can be as high as 75.8%,1.81 times,1.34 times and 1.31 times than that of TiO2(sintered under the temperature of 500℃), F(0.5)/TiO2, Zn(1.0%)TiO2, respectively.(2) La(0.05%)/B(2.0%)/TiO2, made under 500℃, shows best photocatalysis activity and the degradation rate of degrading methyl orange can be as high as 92.0%,2.2 times as high as TiO2(sintered under 500℃),2.20 times La(0.05)/TiO2 and 1.45 times B(2.0%)TiO2. In general comparison, the order of photocatalysis activity of each Tio2 specimen to visible light from high to low is: La(0.05%)/B(2.0%)/TiO2> La(0.1%)TiO2> F(0.5%)/Zn(1.0%)/TiO2> B(2.0)/TiO2> TiO2. Thus it can determine the optimal mixing modified make condition, that is, the optimal adding amount of La and B are 0.05% and 2.0% respectively, and the best temperature is 500℃ (3) In the study of its application in paper wastewater, single factor experiment of 0.05%La/2.0%B/TiO2 specimen, whose photocatalysis result is optimal, was conducted. It can be found that pH value in the solution, photocatalysis amount, light time and H2O2 amount all have impact in the degradation rate of degrading waste by TiO2 photocatalysis. By orthogonal test, it draws a conclusion that the optimal technology condition of photocatalysis degradation of paper wastemter is pH=7, TiO2 amount is 3g/L, H2O2 is 1.25ml/L, and the light time is 150min. Under this condition, COD clearance can be as high as 86.5%using xenon lamp as light resource.It indicates by XRD analysis that grain size of specimen can be decreased effectively by adding and modifying TiO2 specimen under the same condition, and inhibits the change of TiO2 crystal formation from anatase to rutile. Meanwhile, the UV-Vis analysis shows that the mixture modification can improve the photocatalysis activity of TiO2 specimen under the visible light.