【作者】 董伟；

【导师】 丁士文；

【作者基本信息】 河北大学 ， 无机化学， 2008， 硕士

【摘要】 介孔TiO2因其具有高比表面积,发达有序的孔道结构,孔径尺寸在一定范围内可调,表面易于改性等特点,可以有效地增强纳米TiO2光催化、光电转换等功能,使其在水处理、空气净化、太阳能电池、纳米材料微反应器、生物材料等方面表现出广阔的应用前景而备受瞩目。然而,TiO2是宽禁带材料,通常需要用紫外光源(λ≤388nm)来激发,而太阳光谱中紫外光部分仅占5%,这就导致太阳能利用效率低,在很大程度上限制了它的实际应用。为了提高二氧化钛的光谱响应和对太阳光的利用率,人们做了大量的工作对二氧化钛进行改性,提出了染料敏化、贵金属掺杂以及利用溶胶-凝胶技术进行半导体-半导体复合等方法,但上述方法存在光化学稳定性差、原料成本高、操作工艺繁琐等弊端。为了弥补上述方法的不足,本文做了如下工作：第一部分,利用锐钛矿相和金红石相复合后的混晶效应,通过制备具有两种结构的混晶粉体的方法,对二氧化钛进行结构改性。本文采用独特的两步合成法,制备出高催化活性的二氧化钛粉体,表征结果显示产品具有混晶结构,颗粒呈球形,大小均匀,分散性好,且光吸收性能和光催化活性均明显高于纯相产品,同时对产品特殊结构形成的机理以及光催化过程中pH值、染料浓度和不同光源等影响因素进行了详细讨论。第二部分,利用表面活性剂大分子链的空间位阻效应,高分子网络的阻隔作用,通过制备具有介孔结构粉体的方法,对二氧化钛进行结构改性。本文采用多种单一、两两复合的表面活性剂做为模板和结构导向剂,制备出了具有高吸附性和催化活性的介孔二氧化钛粉体。表征结果显示,该产品具有介孔结构,其N2吸附一脱附等温线为典型的介孔结构吸附-脱附等温线Langmuir IV型,样品粒度均匀,孔径分布较窄。采用复合表面活性剂制得的介孔材料的吸附与光催化降解性能均好于单一表面活性剂制备的介孔氧化钛材料和无介孔结构存在的二氧化钛材料。同时考虑了在反应过程中表面活性剂的类型和配比的选择比例,反应温度,反应时间,焙烧温度等因素对介孔结构形成的影响进行了详细讨论。第三部分,纳米混晶TiO2介孔材料的实际应用。本文用此复合介孔材料对酸性红3R染料等有机染料和工业含氰废水进行了光催化降解实验。实验结果表明：酸性红3R染料在太阳光下照射40min后,脱色率可达到100%；工业废水在日光灯下照射3h后,废水中CN-的含量可完全达到污水综合排放标准(GB8978-1996)中的一级排放标准。更多还原

【Abstract】 Mesoporous TiO2 has attracted much attention because of its high specific surface area, ordered drill way structure, adjustable aperture size and surface modification, which effectively enhance function of photocatalysis and photoelectric conversion. TiO2 has widely application prospect in water treatment, air purge, cell battery, nanomaterial mini-reactor and biological materials. But TiO2 is a wide band semiconductor, and it is excited only by ultraviolet light resource (wavelength lower than 388nm). Ultraviolet light possesses 5% in the whole sunlight, which leads to low utilization rate of photos and limited application. For the sake of widening spectral response range of TiO2 and enhancing the utilization rate of sun’s rays, a lot of work has been done. People put forward to many modified methods, including the sensitization with organic dye, adulteration with notable metal, and complex of semiconductor with Sol-gel method. But above methods have some disadvantages of poor stability, high cost and complicated synthesizing technics. In order to offset these shortages, woke below is done in this paper:Firstly, preparation of composite-crystal structure TiO2 was another modified way, using composite-crystal effects between rutile phase and anatase phase in TiO2 base. A special modified way was reported in this paper. High photocatalytic active nano-TiO2 powder was prepared by two-step synthesizing method, and characterization results showed that the sample has composite-crystal structure and spherical morphology, and the distribution of particles is well-proportioned. Furthermore, the sample’s perfect properties of photo-absorbance and photocatalysis were observed, and sample’s mechanism of structural formation, several factors such as pH value, initial concentration of dye and different light resources in the process of photo-degrading acid dyes were discussed in detail.Secondly, preparation of mesoporousl structure TiO2 was another modified way, this method utilizes the positional hindrance effect of the long chain in space, obstruction effect of high polymer net. High adsorption and photocatalytic active nanometric mesoporous TiO2 was preparated on different organic surfactant template. The characterization results showed that the samples have mesoporous structure and the N2 adsorption-desorption isotherms of the materials exhibited typical LangmuireⅣpattern. The crystallites dispersed well and the pores structure among particles was mesoporous texture lacking of long-range order.. The samples using composite surfactant template had the better function than other titania materials Meanwhile, the best crafts parameters were obtained through optimizing various factors, for example, surfactants ratio of composite templates, reaction temperature, reaction times, and calcination temperature influencing the reaction.Thirdly, the practical application of nanometric composite-crystal TiO2 mesoporous material is effective. This article studies photocatalysis degradation experiment to acid red 3R dye and cyanide industrial wastewaters, using the composite-crystal mesoporous material. The experiment results indicate that the decolorizing rate of acid red 3R dye could be to 100% after 40min under sunlight, the CN- content of industrial wastewaters could reach primary emission standard after 3h under sunlight lamp.更多还原