【作者】 林立；

【导师】 周继承；

【作者基本信息】 湘潭大学 ， 化学工程， 2006， 硕士

【摘要】 二氧化钛光催化氧化技术是一种高级氧化技术,该技术在室温下几乎可以无选择性的氧化水环境和大气环境中的有机污染物,而且有望直接利用太阳能,在新能源开发和环境保护领域有着巨大的应用前景,吸引了分别来自物理、化学和材料等领域的学者们的广泛兴趣。在围绕太阳能的转化和储存,探索光催化过程的原理,致力于提高光催化效率,并拓展其应用领域做了大量的研究。尽管二氧化钛光催化氧化技术有着十分广泛的应用前景,然而现在大多数研究都处在实验室阶段,实际应用比较少。主要是因为现有的光催化剂效率不高、对可见光利用率低是阻碍其实用化的主要因素,其次就是高效光催化反应器的设计,再有光催化剂的固载化或回收都是实用化要解决的问题。围绕高活性纳米尺度的二氧化钛粉体、晶须和纤维的制备以及在此基础上各种高性能的复合纳米结构的光催化剂的研发是当前的热点。目前国内外纳米二氧化钛的生产工艺主要可以分为气相法和液相法,气相法属于高温反应,有腐蚀性,对设备的设计和维修要求高,技术难度大,其关键技术为国外少数大公司垄断。液相法主要包括溶胶凝胶法、水热法、微乳液法、均匀沉淀法等,但都不同程度的存在原料昂贵,操作条件复杂,工艺流程长等缺点。而液相法特别是以无机钛盐为原料的反应沉淀法是最具有工业化前景的方法。同时为了促使二氧化钛的光生电子空穴对的分离,拓展其在可见光区的光谱响应范围,达到充分利用太阳光的目的,一些研究者通过贵金属复合,过渡离子和无机阴离子掺杂,与其他半导体复合以及表面光敏化等一系列的方法进行了研究,本文针对以上现状,主要做了以下几个方面的工作。本文在课题组已有的研究工作基础上,结合相关文献,通过比较分析硫酸钛和四氯化钛的不同水解机理,结合低温控制中和水解法制备纳米二氧化钛研究中关于在沉淀过程中对前驱体组成的控制机理,开辟了一条以四氯化钛为原料氨水为水解沉淀剂控制中和水解合成纳米二氧化钛的工艺路线。分别考察了pH值,温度和浓度对反应过程和产品的综合影响,结果表明最佳工艺反应条件为反应温度为常温, pH值为2.2-4.2之间,浓度为0.8mol/l。该条件下可以得到前驱体为具有锐钛晶型的H2TiO3使粒子在焙烧中晶粒生长缓慢,可以得到粒径为20纳米左右的纳米二氧化钛,收率在97%以上,通过600-800℃热处理得到的锐钛矿纳米二氧化钛具有最佳光催化活性。二氧化钛在光激发下的光生电子空穴对可以参与氧化还原反应,本文利用光催化的这一机理采用直接光催化还原的新方法制备了纳米复合光催化剂Ag@TiO2结果表明,少量的银以纳米颗粒分散沉积在二氧化钛的表面可以显著提高纳米二氧化钛的光活性,有无空穴捕获剂对制备出的Ag@TiO2活性影响不大,更多还原

【Abstract】 Photocatalytic oxidation technology is one kind of advanced oxidation technology which have been developed from 70 years in the 20th century.This technology have many virtues,for example,it can completely oxidize almost all the organics harmful pollutants which exist in water and air in room temperature,and can make use of sunlight energy,so have great application prospects.lots of scholars who come from physical,chemical and material field and so on have been mostly interesting in the field. a great quantity works have been carried out for the transformation and storage of sorlar energy,founding the theory of photocatalytic process,aiming to increase the photocatalytic efficiency,and extending the application field.At the present time ,TiO2 is the most important material studied in photocatalytic field.because its cheap ,safety and very stable physical-chemical properties.Although the titanium dioxide photocatalytic oxidation technology has the extremely widespread application prospect, however the most present research works occupies the laboratory stage, the practical application are very few.Firstly The most important factor which hinders its practical is the low efficiency and poor using of the visible light.secondly,the design of high efficiency photocatalytic reactor and the fixation and recycling of the photocatalyst also limit the practical application. the preparation for high-activity nanometer criterion titanium dioxide powder,the crystal and textile fiber as well as the research and development for high performance compound nanometer structure photocatalyst in this foundation is present hot Topic.The mainly production technology of Nano-TiO2 can be classified with vapor phase method and liquid phase method. Vapor phase method belong to high temperature reaction,have strongly corruption properties and high ask for designing and maintenance to the equipment.The key technology have been monopolized by few companies abroad.The liquid phase include sol-gel,hydrothermal, microemulsion, even precipitation method. But these methods exist some shortcoming such as expensive raw material, complex operating condition, long technical process and so on. The reactive-precipitation method with inorganic titanium salt as material posses most prospects. At the same time in order to urge the titanium dioxide photoproduction electron-hole pair separation, develop its response scope in the visible light spectral, achieve goal for sunlight using, precious metal compound, the transition ion and the inorganic anion doping, compound with other semiconductors更多还原