【作者】 武丽娟；

【导师】 雷绍民； 管俊芳；

【作者基本信息】 武汉理工大学 ， 矿物加工工程， 2007， 硕士

【摘要】 纳米TiO₂因其光催化活性高、无毒、价廉、稳定性好而引起人们广泛关注。但是TiO₂的带隙较宽（3.2ev），能利用的太阳能仅占太阳能总量的大约3％，论文采用稀土La掺杂以拓宽TiO₂光谱响应范围并提高其可见光催化能力。论文采用sol-gel法制备了La掺杂TiO₂／高岭石光催化材料。研究了掺杂量、焙烧温度、焙烧时间、水解温度和水解时间五种因素对催化剂光催化活性的影响。分别以模拟印染废水酸性红G、罗丹明B和偶氮染料工业废水为反应物，研究了La掺杂TIO₂／高岭石光催化剂的液相光催化性能，考察了降解条件对其光催化性能的影响，着重考察了多种因素（催化剂用量，反应时间，废水pH值，光照条件，氧化助剂H₂O₂）对La掺杂TiO₂／高岭石光催化剂紫外光下光催化降解污染物的影响以及催化剂在自然光下的光催化反应活性。分别采用XRD、Raman、FTIR和TEM技术对光催化剂的晶体结构、分子结构及表面形貌加以表征，探讨了La掺杂对TiO₂／高岭石基光催化剂光催化活性的影响和稀土离子掺杂机理。结论如下：1．La掺杂TiO₂／高岭石光催化剂的最佳制备条件为：掺La量0.5％，焙烧温度550℃，焙烧时间2h，水浴温度50℃，水浴时间3h。2．XRD、Raman、FTIR和TEM分析。样品XRD光谱显示：La掺杂后，高岭石基材表面TiO₂晶体为锐钛矿相，未见金红石相的X衍射特征峰，与Raman光谱测试结果一致；FTIR测试表明La至少被复合到TiO₂晶体表面或进入TiO₂晶体中。由于热效应差异导致TiO₂晶型转变温度发生改变，提高了TiO₂由锐钛矿相向金红石相的转变温度。TEM照片显示，TiO₂晶体颗粒均匀分布在片状基材高岭石表面。3．研究表明，紫外光下，La掺杂后的光催化剂对酸性红G溶液、罗丹明B溶液和偶氮染料工业废水的脱色率最高分别为97.03％、98.18％和99.57％，比未掺杂样品对废水脱色率分别提高了14.36％、17.45％和12.34％；自然光下，La掺杂催化剂比未掺杂样品对酸性红G溶液、罗丹明B溶液和偶氮染料工业废水的脱色率也分别提高了13.87％，6.73％和5.96％。La的掺杂能有效地使TiO₂的光谱响应范围向可见光区拓展。4．废水初始pH值对其脱色率有明显影响。在强酸性条件下，催化剂废水的脱色率均在90％以上。5．适量外加H₂O₂能促进·OH的生成，提高光催化反应速率和效率。更多还原

【Abstract】 Nano-TiO₂ photocatalysts have been the focus of the investigations, for its high photocatalytic activity, no toxicity, low price and chemical stability. However, the band gap of TiO₂ is large（Eg=3.2eV）, and it is only active in the ultraviolet region which is about 3% of the overall solar intensity. La-doped was adopted to extend the light responsible range and improve the photocatalytic activity of TiO₂.In this thesis, La-doped nano-TiO₂/Kaolinite was prepared with sol-gel method. These factors has been researched such as the dosages of La, calcination temperature and time, hydrolysis temperature and time which affecting crystal structure and photocatalytic activity. The acid red G, RhB, AZO-dye has been degradated to make use of the photocatalyst. The photocatalytic activity was also evaluated under the visible light and UV light irradiation. The influences of photocatalyst dosage, degradable time, solution pH, difference illumination condition, H₂O₂ quantity were investigated. XRD, Raman, FT-IR and TEM were adopted respectively to characterize the structure of the molecular and crystal, and morphology of TiO₂. As the same time the doping mechanism has been also discussed.The conclusions are as follows:1. The optimized process conditions of preparation are La doping dosage of 0.5%, calcined at 550℃for 2h and hydrolyzed at 50℃for 3h.2. The XRD, Raman and FT-IR were adopted to characterize and analyze the mechanisms of modification. TiO₂ crystal doped with La presented as phase of anatase only on the surface of kaolinite in XRD spectra of samples. The results obtained are in fair agreement with the results from the analysis of Raman. The results showed that the doping of La inhibited the phase transformation of TiO₂. Results of FTIR spectroscopy testing showed that La entered into TiO₂ crystal lattice or combined on TiO₂ surface at least. Transforming temperature of TiO₂ crystal structure was improved due to heat effect differences. It could be seen that TiO₂ had been loaded on the surface of kaolinite successfully and uniformly from photo-TEM which is still a positive factor to promote the photocatalytic rate. 3. Acid red G, RhB and AZO-dye wastewater were degraded in order to evaluate the photocatalytic activity of La-doped nano-TiO₂/Kaolinite. The results showed that under the UV-light, the rate of decolorization of wastewater were 97.03%, 98.18% and 99.57% respectively; compared with the un-doped nano-TiO₂/Kaolinite, the decolorization rate increased 14.36%, 17.45% and 12.34% respectively, and the rate of decolorization increased 13.87%, 6.73% and 5.96% respectively under the visible light. The photocatalytic effects enhanced obviously with doping of La in sunlight. Doping element La could develop effectively towards visible light area.4. The initial pH of wastewater had obviously influence on the decolorization rate. It was more than 90% in acidic solutions.5. Additive H₂O₂ will benefit to change of hydroxy·OH and enhence the photocatalytic rate and efficiency.更多还原