【作者】 李经；

【导师】 谭欣；

【作者基本信息】 天津大学 ， 化学工程， 2005， 硕士

【摘要】 近年来,纳米TiO₂因具有高的光催化活性、良好的化学稳定性、并且廉价无毒等诸多优异性能,被广泛应用于有机污染物降解、污水处理、空气净化等领域,成为材料科学中的研究热点之一。而如何更有效地发挥其功能是保证光催化反应顺利进行乃至工业推广的关键环节。以污水处理为例,TiO₂本身对有机物的吸附能力较弱,若采用吸附性载体负载TiO₂则可显著提高TiO₂的光催化效率。吸附剂作为载体的最大优势是可以将有机物吸附到半导体粒子的周围,增加局部浓度及避免中间产物挥发或游离,加快反应速度。目前,这方面工作已取得了一定的进展。本文即在这一课题背景下采用溶胶凝胶工艺,通过程序控温进行煅烧处理,制备出具有较高光催化活性的纳米TiO₂。其晶粒尺寸在20～40nm左右。并采用多次浸渍-干燥-煅烧操作将其负载在活性炭上,形成负载型光催化剂AC/TiO₂。本文探讨了溶胶凝胶参数、负载量﹑载体孔径、稀土化合物掺杂等因素对光催化降解亚甲基蓝溶液的影响。通过TG﹑BET﹑SEM﹑XRD等分析手段对负载型催化剂的表面形貌、物化性能、晶态结构和价态等进行了表征。并实验完成了负载型催化剂用量、光强、亚甲基蓝初始浓度、pH值、H₂O₂添加量对脱色率的条件优化。研究表明:在升温至500℃后,可制备出具有较高活性的锐钛型TiO₂,其在活性炭上的最佳负载量为11.3%。镧和铈两种离子均可以显著细化TiO₂的晶粒尺寸。但只有La可以提高AC/ TiO₂的催化活性,其具体的光催化机理也通过XRD分析、XPS分峰拟合给出了合理的解释。更多还原

【Abstract】 Recently, because nano TiO₂ are of such good performance as chemical stability, high photocatalysis, low cost, no poison and so on. It has been applied to organic compound decomposition, sewage treatment and air purification broadly. TiO₂ has become a research hotspot in material field. But how to develop its function effectively has also been a key step to ensure photocatalysis in good progress and to promote for industries. Take sewage treatment for example, TiO₂ has weak adsorption capability for organic compound by itself. If we introduce adsorptive carriers to load h, Photocatalytic efficiency will increase obviously. It is adsorptive carriers′s maximum advantage that they can adsorb organic compound around semiconductor particle, improve local concentration and avoid middle materials volatile or escape. Such behavior can accelerate reaction. At present, Relative researches have made some progress. On the basis of the above background, the paper adopted Sol-Gel method to prepare nano TiO₂ of well photocatalytic property with the help of instrument of program controlling temperature. Its crystal size is at the range of 20⁴0nm.Moreover, the paper continue utilize dipping-drying-heating several times to load TiO₂ onto activated carbon forming photocatalytic agent AC/ TiO₂. The relations among Sol-Gel parameters, loading quantity, carrier pore width, rare earth intermingle and so on with photocatalytic degradation MB resolution are also evaluated. Physiochemical properties, morphology, crystalline phase and value of AC/TiO₂ were determined by methods of TG, BET, XRD, SEM. Lastly, the paper complete experiment conditions optimization. Parameters include amount of AC/ TiO₂, illumination intensity, initial concentration of MB, pH value and H2O2. As can be seen from the results: anatase TiO₂ can obtained with high photocatalysis after heating gel up to 500℃. As far as TiO₂ is concerned, there is a prime coating amount of 11.3﹪ on activated carbon. La and Ce ion can either reduce crystal size of TiO₂ evidently. However, only La can improve photocatalysis of AC/ TiO₂. For detailed mechanism of photocatalytic degradation, the paper give some reasonable explain through XRD analysis and XPS simulation.更多还原