【作者】 林会亮；

【导师】 周国伟；

【作者基本信息】 山东轻工业学院 ， 制浆造纸工程， 2007， 硕士

【摘要】 介孔材料是一类孔径分布在2-50 nm之间的多孔材料,具有比表面积大、孔隙率高、孔径分布窄、孔排列有序的特点,使其一问世即成为工业应用（如光催化、离子交换、分子筛、吸附和分离等）的首选。非均相半导体光催化技术在水污染控制,尤其在处理废水中难降解有机污染物方面具有独特的优越性,纳米TiO₂作为一种性能优良的光催化剂已成为治理环境污染的研究热点,本实验通过制备具有较大比表面积的介孔TiO₂及TiO₂-SiO₂介孔复合材料,结果表明介孔TiO₂比纳米TiO₂具有更优异的光催化性能,少量SiO₂掺杂有利于提高介孔TiO₂的光催化活性和反应效率,在处理废水有机污染物等方面具有广阔的应用前景。本项研究以钛酸四丁酯（TBOT）为钛源,正硅酸乙酯（TEOS）为硅源,三嵌段共聚物（P123）为模板剂,溶胶-凝胶法合成了介孔TiO₂及具有不同钛硅摩尔比的TiO₂-SiO₂介孔复合材料,用小角X射线衍射（SAXRD）、X射线粉末衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）,红外光谱（FT-IR）、N2吸-脱附和紫外可见吸收光谱（UV-Vis）等分析手段对产物结构和光学性能进行了表征。结果表明:400℃煅烧得到的样品XRD谱图中仅在2θ=25.3°（101）,37.9°（004）,47.8°（200）,54.3°（211）处出现锐钛矿相特征衍射峰,该特征峰随着钛硅比的增加而增强,但XRD谱图中并未出现SiO₂的特征峰,表明SiO₂以无定形的形式存在于复合材料中;SAXRD图中在2θ<1°处有明显的介孔材料的特征衍射峰;TEM图中有明显的短程有序的孔径分布,且分布较均匀;FT-IR显示TiO₂与SiO₂基质之间存在着Ti-O-Si键; N2吸脱附曲线表明合成材料具有介孔结构,随着SiO₂含量的增强,复合材料的孔径减小,比表面积增加;UV-Vis分析表明,复合材料吸收峰发生红移,使光谱响应范围向可见光拓展,提高TiO₂对太阳光的利用率。以制浆蒸煮黑液、对氯苯酚和对硝基苯酚为目标降解物,考察了SiO₂复合对介孔TiO₂光催化活性的影响。发现介孔TiO₂的光催化活性优于纳米TiO₂,而SiO₂少量掺杂的介孔TiO₂光催化剂则比纯介孔TiO₂有更好的光催化性能,能有效提高对蒸煮黑液和对硝基苯酚光催化降解;考察了催化剂的种类、光照时间、催化剂的用量、初始pH、通氧方式等对降解制浆黑液的影响因素。探明了在反应条件为:催化剂用量为1.5 g/L、初始pH = 6、连续通氧条件下降解效果最佳,在紫外光照射下,反应12 h后,少量SiO₂的存在能有效促进介孔TiO₂对蒸煮黑液的光催化降解,提高蒸煮黑液的COD_Cr和色度的去除效果。以介孔TiO₂-SiO₂复合材料（Ti/Si=100:1）为催化剂,反应体系中COD_Cr及色度的去除率分别达94.9%和97.6%,较介孔TiO₂分别提高了5.8%和5.4%,较纯纳米TiO₂分别提高了44 %和12.8 %。更多还原

【Abstract】 Mesoporous material with pore size between 2-50 nm, high specific surface area, large pore volume and narrow pore size distribution, have considerable potential for wide use in photocatalysis、ion exchange、molecular sieves、adorption and separation applications. Heterogeneous photocatalysis by semiconductors has unique advantages in water pollution control,especially in the treatment of waste water containing poisonous organic compounds which are hard to be destroyed. Titanium dioxide （TiO₂）, which can decompose most organic pollutants into inorganic substances under UV irradiation, has become a hot research area because of its attractive application in the treatment of environmental pollutants. In this research, we prepared mesoporous TiO₂ and mesoporous TiO₂-SiO₂ complex materials with more high specific surface area, and the results show that the mesoporous TiO₂ has the better properties than the nano TiO₂ and the complex materials have more superior properties than the pure mesoporous TiO₂ or SiO₂, then they have better photocatalytic properties in the degradation of organic wastewater.Mesoporous TiO₂ and TiO₂-SiO₂ photocatalysts （with different molar ratio of Ti/Si） has been successfully synthesized by using nonionic triblock copolymer （P123） as template agent via sol-gel reactions of tetrabutyl titanate （TBOT） and tetraetethyl orthosilicate （TEOS）, then the prepared material（safter calcined at 400℃for 4h） were characterized by Low-angle X-ray diffraction （SAXRD）, X-ray diffraction （XRD）, Transmission electron microscopy （TEM）, Scanning electron microscope（SEM）, Fourier transform infrared spectrophotometer （FT-IR）, N2 adsorption-desorption isotherm, Ultraviolet-visible （UV-Vis）, and so on. The SAXRD shows the samples possess a short - range ordered mesoporous structure but lack of a long - range ordered structure; the XRD shows the samples were all anatase and the silica or silicate in the prepared samples exists as amorphous state ; TEM shows that the synthesized materials have lots of channels and possess a short-range ordered mesoporous structure; FT-IR analysis shows the formation of the band for Ti-O-Si vibration between TiO₂ and SiO₂ matrix; BET analysis shows the synthesized materials possess the mesoporous structure（BET surface area=105.41m2g-1, total pore volume 0.2039 cm3g-1, average pore diameter 7.74 nm for TiO₂）, also synthesized materials’s the BET surface area increases and the pore diameter decreases with the increase of the silica content. From UV-Vis analysis, the absorption spectra of TiO₂-SiO₂ shifted toward visible light region and the absorbance dramatically increased with the increase of silica content.The presence of mesoporous structure and a little silica in TiO₂ crystalling were found to promote the photocatalytic activity of TiO₂ in degradation p-chlorophenol、p-nitrophenol and black liquor from pulping and papermaking. The results showed the mesoporous TiO₂ had the better photocatalytic properties than nano TiO₂ and the mesoporous TiO₂ with the little doption of silica had the better photocatalytic properties than mesoporous TiO₂. The influencing factors on the degradation of black liquor such as the kinds of catalyst, light application time, catalyst dosage, initial pH value, aerating mode etc. in the photocatalysis system were investigated. The presence of mesoporous structure and silica in TiO₂ crystal were found to improve the removement of efficiency of chemical oxygen demand (COD_Cr) greatly. Its COD_Cr was decreased from 450 mg/L to 46.14 mg/L and 23.07 mg/L, respectively. The removing rate of COD_Cr of black liquor from pulp was up to 89.7 % and 94.9 % and the removing rate of chroma was 92.6 % and 97.6 %. The best parameters during the photocatalysis processes were determined also, its best conditions were the catalyst （Ti/Si=100:1） dosage was at 1.5g/L, the initial pH = 6 with continuous aerating and reaction time 12h.更多还原