【作者】 徐克涛；

【导师】 陈拥军；

【作者基本信息】 大连理工大学 ， 能源与环境工程， 2012， 硕士

【摘要】 Ti02半导体材料以其效率高、无毒、化学稳定性好等优点逐渐成为一种重要的光催化剂。在水净化实际应用方面,固定化二氧化钛薄膜因解决了悬浮态光催化剂难以分离回收等问题而倍受广泛的关注。本文采用溶胶-凝胶法和浸渍提拉技术制备了Ti02薄膜,并对其光催化性能进行了研究。主要研究内容和结论如下：(1)以钛酸异丙酯,无水乙醇,去离子水,乙酰丙酮,吐温20为原料制备含钛的溶胶,其中吐温20是一种表面活化剂,用来对Ti02薄膜改性。利用XRD、SEM、UV-Vis、 BET对薄膜的性能进行了表征。分析Ti02薄膜制备过程中加水量、反应温度、镀膜次数、提拉速度、pH值以及热处理温度等重要因素对薄膜结构和光催化性能的影响。结果表明：在酸性溶胶,水与钛酸异丙酯的摩尔比例为7：1,反应温度为20℃,提拉速度为1.33mm·s-1的条件下制备的Ti02薄膜具有良好的透光性,吸收紫外线能力强,二氧化钛颗粒均匀致密的附着在玻璃基体表面。(2)以亚甲基蓝溶液为污染物模型,对Ti02薄膜的光催化性能进行了研究。分析一些重要的因素对光催化性能的影响,并与粉状Ti02颗粒光催化性能进行了对比,同时分析了薄膜的稳定性。结论如下：加入吐温20后能够明显提高Ti02薄膜光催化效率；催化剂量增大、水量增多以及镀膜次数增加均能提高光催化效率且存在最佳值；亚甲基蓝的降解率随焙烧温度的升高先增大后减小,最佳温度为450℃；TiO2薄膜的光催化效率要低于TiO2粉末,并且紫外光条件下的降解率高于可见光；亚甲基蓝溶液的降解率随初始浓度升高而降低,并且Ti02薄膜的光催化稳定性较好。(3)TiO2薄膜光催化降解亚甲基蓝动力学研究和分析。结论如下：增加催化剂量有助于提高亚甲基蓝的光催化速率,直到出现最优的催化剂量；光催化速率常数随着溶液初始浓度的增大而减小；溶液的pH值是影响光催化反应速率的重要因素,在反应液中加入浓硝酸或者氨水可以增强反应速率；反应速率常数随着去离子水量增加而增大；实验中最高的反应速率常数,对应着热处理温度最佳值(450℃)；纳米Ti02薄膜光催化降解亚甲基蓝溶液的反应均符合Langmuir-Hinshelwood (L-H)动力学模型,且光催化氧化过程为一级反应。更多还原

【Abstract】 has been considered to be an important photocatalytic material due to its many advantages such as high efficiency, low cost, non-toxicity, and good chemical stability. Compared with suspended TiO2powder as photocatalyst for water treatment, immobilized TiO2thin film does not need to be separated after water purification. Therefore, the film type of TiO2photocatalyst has been paid more attention. In this dissertation, TiO2thin films have been prepared by a dip coating sol-gel method. The photocatalytic performances of TiO2thin films have been systematically investigated. The main research work and conclusions can be summarized as follows:In this dissertation, The Ti sol is composed of titanium isopropoxide, absolute ethyl alcohol, de-ionized water, acetyl acetone and Tween-20. Tween-20, as a kind of surfactant r, is used to modify TiO2films. The properties of the as-prepared TiO2films have been characterized by XRD, SEM, UV-visible spectrometer and BET. The effect of important preparation parameters, including the molar ratio of H2O/titanium isopropoxide, pH of the sol, calcinations temperature, the dip coating speed and number, on the structure and photocatalytic activity of the as-prepared TiO2films are investigated. The experimental results show that TiO2films is obtained under the conditions of acid sol, H20/titanium isopropoxide molar ratio of7:1,20℃of reaction temperature,33mm·s-1of dip-coating peed, which has good light transmission and UV absorbance. And TiO2particles attached to the surface of glass uniformly.The photocatalytic properties of TiO2thin films have been studied using methylene blue as a model pollutant in water. Some important factors that may affect photocatalytic properties of TiO2films in the reactor have been analyzed. A comparative study on photocatalytic properties of immobilized TiO2films with suspended TiO2particles has been discussed. And the stability of the film has been analyzed. The conclusions are as follows: adding Tween-20into Ti sol can obviously increase photocatalytic efficiency of TiO2thin films; the increase of photo catalytic dose, water, coating cycle all can improve the photo catalytic efficiency and have the best value;. With the enhancement of calcinations temperature, the degradation rate of methylene blue increases firstly and then decreases, the optimum temperature is450℃; our experimental results have confirmed that photocatalytic activity of TiO2thin film is less than that of suspended TiO2powders. In addition, the photocatalytic degradation rate of methylene blue by TiO2films under ultraviolet light radiation is higher than that under visible light radiation; increasing initial concentration of methylene blue can lead to the decrease in the degradation rate of methylene blue. The stability of the as-prepared TiO2thin films is good.The photocatalytic oxidation kinetics of TiO2films on the degradation methylene blue has been studied and analyzed. The conclusions are as follows:the reaction kinetics constant can be enhanced by increasing catalyst loading until the optimum catalyst loading can be reached; with the increase of initial concentration, the photocatalytic rate constant decreases; the pH value of solution is an important factor for the influence of photocatalytic rate constant, it seems that adding HNO3or NH3-H2O into the reaction liquid can lead to the enhancement in the reaction rate constant. In addition, with the increase of the amount of water in the sol, the reaction rate constant increases; there is also optimum calcinations temperature (i.e.,450℃) for the highest reaction rate constant. The photocatalytic oxidation of methylene blue by the TiO2films can be described by a Langmuir-Hinshelwood (L-H) model. It can be found that the photocatalytic oxidation reaction of methylene blue belongs to a first-order reaction.更多还原