【作者】 文桂林；

【导师】 刘惠涛；

【作者基本信息】 兰州大学 ， 分析化学， 2006， 硕士

【摘要】 近年来,用纳米TiO₂等半导体光催化技术降解水中有机污染物的研究成为环境科学领域的一个热点。光催化技术具有常温、常压下进行,能彻底破坏有机污染物,无二次污染等优点。目前,纳米TiO₂制备方法很多,但制备方法的实际操作性和产品的最终催化性能参次不齐,从中找出一种简单实用、能制备出高活性而稳定的纳米TiO₂光催化剂的方法尤为重要。同时,纳米TiO₂自身也存在着一些不足,非常有必要对其进行合理的改性。本论文对最为常用的几种液相制备方法进行了系统的比较研究,并通过掺杂SiO₂对其进行了改性,主要结果如下: ☆ 采用化学沉淀法、溶胶-凝胶法和微乳液法等三种方法,在相近条件下制备了纳米TiO₂,并进行了系统的比较研究。XRD及TEM测试结果显示:化学沉淀法制备方法简单,且样品为锐钛矿相、颗粒均匀细小。以次甲基兰溶液的光催化降解为模型反应,其光催化性能良好。 ☆ 采用化学沉淀法、溶胶-凝胶法和微乳液法制备了TiO₂-SiO₂复合材料。结果表明:SiO₂的掺杂稳定了TiO₂的晶相,抑制了TiO₂粒子的长大,TiO₂-SiO₂复合材料的尺寸明显小于单一的TiO₂粒径。三种制备方法中,化学沉淀法的制备过程相对简单,且样品的掺杂效果最好。 ☆ 制备了不同SiO₂含量的TiO₂-SiO₂复合材料。光催化实验结果显示,在SiO₂掺杂量较低的情况下,随着SiO₂含量的增加,化学沉淀法和溶胶-凝胶法制备的样品的性能得到了改善。更多还原

【Abstract】 In recent years, the heterogeneous photocatalysis for the degradation of organic water pollutants using nano-TiO₂ semiconductors has been studied extensively in environmental science. The photocatalytic degradation technique has many advantages, such as carried out under ambient temperature and normal pressure, decomposing organic pollutants completely without second pollution. There are many methods in the preparation of nano-TiO₂ powders at present, but the photocatalytic activity of nano-TiO₂ powders prepared by various methods is much different. It is very important to find out a better method by which the catalysts possess good photocatalytic activity and thermal stability. Except for those advantages, nano-TiO₂ powders have some deficiencies, so it is necessary to modify TiO₂ by the adulteration to improve its photocatalytic activity. In this thesis, the comparative study of the properties of nano-TiO₂ powders prepared by different preparation methods was carried out. We did some experiments about the modifacation of TiO₂ through the SiO₂ adulteration, and the photocatalytic performances of the samples were examined. Some results were obtained as follows:Nano-TiO₂ powders were prepared by chemical precipitation method, sol-gel method and microemulsion method, respectively. The comparative study of the properties was carried out. Different preparation methods led to morphological and structural changes. X-ray diffraction （XRD） and transmission electron microscope （TEM） results showed that the particles synthesized by chemical precipitation method are single crystals of the anatase phase, with uniform and smaller particle size. Photocatalytic performance investigation of the TiO₂ particles in the photodegradation reaction of the methylene blue solution demonstrated that the TiO₂ powders prepared by chemical precipitation method have higher photocatalytic activity than those prepared by the other two methods.The TiO₂-SiO₂ composites were also prepared by chemical precipitation method, sol-gel method and microemulsion method, respectively. The result showed that the SiO₂ adulteration inhibits the accretion of the paticles, makes the crystal phase more stable and the particle size much smaller than the pure TiO₂. Among the samples prepared by the three methods, chemical precipitation method is relatively simple and the adulteration effect of the sample prepared by this method is the best.The TiO₂-SiO₂ composites with different SiO₂ content were synthesized. The result of photocatalytic experiment showed that on the condition of lower adulteration amount of SiO₂ the photocatalytic activity of the TiO₂-SiO₂ composites prepared by both chemicalprecipitation method and sol-gel method is promoted with the increase of SiO2 content.更多还原