【作者】 田丽红；

【导师】 钟家柽； 昝菱；

【作者基本信息】 武汉大学 ， 无机化学， 2004， 硕士

【摘要】 本文简要介绍了纳米TiO₂半导体催化剂的制备及其在环保领域的应用研究的最新进展及国内外研究现状，并主要进行了纳米TiO₂多孔薄膜光催化氧化NO_x及改性纳米TiO₂固相光催化降解聚苯乙烯薄膜两方面的研究。 以水玻璃为粘贴剂，氟硅酸钠为固化剂，采用涂膜法在钠玻璃板上低温制备了纳米TiO₂光催化薄膜，利用UV-Vis研究了薄膜的紫外吸收性能，SEM观察了其表面形貌，BJH法研究薄膜表面的孔径分布情况。在紫外光照条件下，进行催化薄膜对NO_x的光催化氧化实验，考察了催化剂负载量，反应体系中水蒸气分压以及氧气等因素对NO_x氧化脱除率的影响。实验结果表明：在一定的实验条件下，光照2h后，薄膜对氮氧化物的降解率可达到97.5％，FT-IR法定性分析出反应的最终产物为HNO₃。催化反应后的薄板经水洗后可重复使用，且仍然保持很高的光催化活性。 实验室的研究已经证明用聚合物接枝改性的纳米TiO₂微粒在非极性溶剂中的分散性能良好，所以本文用聚合物接枝改性的纳米TiO₂颗粒作为催化剂，采用包埋法制备了一种新型的可光催化降解的纳米PS-G-TiO₂复合薄膜，并分别在空气中紫外光照，及太阳光照的条件下进行了薄膜的光催化降解实验。利用UV-Vis，GPC，FT-IR，XPS，SEM等分别对光照前后纯的PS膜及PS-G-TiO₂复合薄膜进行分析表征，所有的实验结果均表明PS-G-TiO₂复合薄膜在空气中能被有效的降解。紫外光照396h后，PS-G-TiO₂复合薄膜比纯的PS膜有更高的光降解失重率，达到了31.9％，平均分子量降低率从18.3％上升到53.1％。太阳光照300h后复合膜的光失重率达到了18.9％，而纯的PS膜为0.53％，这说明在太阳光照的条件下，PS-G-TiO₂复合膜同样能达到很高的降解率。同时我们也初步探讨了PS-G-TiO₂复合膜的光催化氧化机理。更多还原

【Abstract】 The paper has reviewed the progress on the research of nanometer semiconductor catalysts. The current development of nano-TiOj photocatalyst has been considered including the preparation of catalyst and the application in degrading environment contaminants. In this thesis, we mainly focus on the study on the gas-phase photocatalytic oxidation of NOx with TiO2 nanometer film and the solid-phase phtotocatalytic degradation of PS film with modified nano-TiO2 catalyst.The porous titanium dioxide nanometer film was prepared on the glass plate with the water glass as binders and sodium fluorosilicate as solidifying agent. The film surface morphology was studied by scanning electron microscope (SEM), and pores distributing of the film was investigated by Barrett-Joyner-Halenda (BJH) method. The gas-phase photocatalytic oxidation of nitric oxides on the TiO2 composite film was carried out in the TiO2 /UV system. After UV-irradiation for 2 h, the photoxidation rate of NOx reached 97.5%. Some important factors affecting the photo-oxidation were also be considered such as the concentration of TiO2, vapour pressure and oxgen. The final product of the photocatalytic oxidation of NOx was detected to be HNO3 by FT-IR. The partial HNO3 was absorbed on the TiO2 surface, causing catalyst deactivation. But when it was washed by water, the catalyst could be reused without the significant loss of catalytic activity.The nano-TiO2 particles were modified by polymer. The photodegradable polystyrene-grafted-Ti02 (PS-G-TiO2) nanocomposite was prepared by embedding the grafted-TiO2 particles into the commercial polystyrene. Solid-phase photocatalytic degradation of the PS-G-TiO2 nanocomposite was carried out in ambient air at room temperature under ultraviolet lamp and sunlight irradiation. The properties of composite films were compared with that of the pure PS films by weight-loss measurement, SEM, gel permeation chromatogram (GPC), X-ray photoelectron spectroscopy (XPS), FT-IR, and UV-Vis spectroscopy etc. methods. The results showed that the photo-induceddegradation of PS-G-TiO2 composite film is significantly higher than that of pure PS film. The weight loss of composite film reached 31.9%, average molecular weight (Mw) of composite film decreased 53.1%, and the number average molecular weight (Mn) decreased 73.2% after 396 h UV-light irradiation. FT-IR analysis and weight loss result indicated that the benzene rings in PS-matrix of composite film were cleaved during UV-light irradiation. The photocatalytic degradation mechanism of the composite film is briefly discussed.更多还原