【作者】 杨信媛；

【导师】 李德良；

【作者基本信息】 中南林业科技大学 ， 环境科学， 2011， 硕士

【摘要】 当前,纳米二氧化钛作为一种性能较好的光催化材料,已经应用于水和空气的净化、细菌和病毒的破坏等领域,成为众多研究者在治理环境污染方面所关注的热点。但目前依然存在的主要问题是：TiO2光催化剂对光的吸收范围狭窄,主要集中在紫外光区,对可见光基本无光催化活性；半导体载流子复合效率高,量子效率低,因而很难在实际中得到广泛应用。为此,为了提高TiO2的可见光催化活性,近年来国内外学者对TiO2的改性进行了大量的研究。本研究以钛酸四丁酯为前驱体,采用溶胶-凝胶法(Sol-Gel)制备了TiO2、F-Zn及La-B共掺杂的TiO2,并利用XRD、UV-Vis、SEM对样品进行了表征,使用500W高压氙灯为光源(模拟太阳光),以甲基橙(40mg/L)溶液模拟染料废水为目标降解物,考察了样品在不同掺杂量配比和焙烧温度下的光催化性能,并且对TiO2光催化氧化技术在实际造纸废液处理中的应用进行了研究。结果表明：(1)经F、Zn掺杂改性后的TiO2样品光催化降解率均得到了不同程度的提高,尤其500℃煅烧制得的F(0.5%)/Zn(1.0%)/TiO2表现出最好的光催化活性,对甲基橙的降解率可达75.8%,分别是活性最好的TiO2(500℃), F(0.5)/TiO2, Zn(1.0%)TiO2的1.81倍、1.34倍和1.31倍。(2)500℃焙烧制得的La(0.05%)/B(2.0%)/TiO2表现出最好的光催化活性,对甲基橙的降解率可达92.0%,分别是活性最好的TiO2(500℃焙烧),La(0.05)/TiO2, B(2.0%)TiO2的2.20倍、1.12倍和1.45倍,综合比较来看,各TiO2样品的可见光光催化活性高低顺序为：La(0.05%)/B(2.0%)/TiO2>La(0.1%)TiO2>F(0.5%)/Zn(1.0%)/TiO2>B(2.0)/TiO2>TiO2。因此可确定的最佳掺杂改性制备条件,即La、B的最佳掺杂量分别为0.05%、2.0%,最佳焙烧温度为500℃。(3)在造纸废液的处理研究中,采用光催化效果最佳的0.05%La/2.0%B/TiO2样品进行单因素实验研究发现,溶液中的pH、光催化剂用量、光照时间和H2O2添加量对TiO2光催化降解污染物降解速率均有显著影响。利用正交试验探讨出造纸废液光催化降解的最佳工艺条件为：pH=7,TiO2用量为3g/L,H2O2添加量为1.25mL/L,光照时间150min。使用500W氙灯为光源,此条件下COD去除率可达到86.5%。XRD分析表明在同等条件下对TiO2样品进行掺杂改性后有效的减小了样品的晶粒尺寸,抑制了TiO2晶型由锐钛矿向金红石相的改变。同时,UV-Vis图谱表明了掺杂改性提高了TiO2样品在可见光下的光催化活性。更多还原

【Abstract】 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.更多还原