二氧化钛光催化剂的制备及其掺杂改性研究

发布时间：2018-06-22 04:44

本文选题：光催化 + 二氧化钛　；参考：《湖南大学》2015年硕士论文

【摘要】：随着工业化进程的加速,人口数量不断攀升,水资源安全成为人们日益关注的问题,然而严重的水体污染加剧了人们对水资源的需求。光催化降解水中污染物已经成为一种有效的解决水体污染的方法。因为它在化学稳定性,市场价格,光催化性能和环境保护等多方面优势明显,二氧化钛半导体受到了研究者们的广泛关注。然而,二氧化钛可吸收的光谱范围狭窄,太阳光利用率和光量子效率低,这些都限制了二氧化钛在实际中的广泛应用。掺杂改性二氧化钛可以拓宽其光响应范围,提高光量子效率,是提高二氧化钛光催化活性非常有效的措施。本论文旨在探究溶胶-凝胶法获取具有高光催化活性二氧化钛的最优工艺;通过调整形貌窄化二氧化钛的禁带,提高光催化性能;同时探究了稀土元素掺杂对二氧化钛晶体结构、光化学性能及光催化活性的影响。主要结论如下所示:(1)以钛酸四正丁酯为原料,乙醇为溶剂,冰醋酸为螯合剂,采用溶胶-凝胶法制备了粉体二氧化钛。探讨了乙醇、水、冰醋酸和pH等条件对凝胶时间和光催化降解甲基橙性能的影响。同时探讨了焙烧温度和焙烧时间对二氧化钛光催化活性的影响。最佳制备条件为:n(C_2H_5O H)/n(Ti(OBu)4)=15;n(H_2O)/n(Ti(OBu)_4)=4;n(CH_3COO H)/n(Ti(OBu)_4)=1;pH=3;500℃焙烧1 h。(2)采用溶胶-凝胶法,在600℃条件下焙烧1 h制备了棒状结构的二氧化钛,与球状二氧化钛相比,棒状二氧化钛的能隙值明显减小。实验探讨了甲基橙初始浓度和催化剂投加量对甲基橙降解率的影响。棒状二氧化钛表现出了优异的光催化性能:当催化剂浓度为0.4 g·dm~(-3),甲基橙初始浓度为10 mg·dm~(-3)时,光照1h后,棒状二氧化钛对甲基橙的降解率达到了95.7%,而球状二氧化钛对甲基橙的降解率只有74%。(3)本文对La、Ce、Pr、Sm四种稀土元素掺杂的二氧化钛进行研究,实验结果表明La、Ce、Pr、Sm的掺杂能提高二氧化钛由锐钛矿相向金红石相转变的温度,并使吸收带边出现不同程度的红移。掺杂元素和掺杂量对二氧化钛的光催化活性影响很大。稀土元素的掺杂可以明显提高二氧化钛的光催化活性,并且存在最佳掺杂量,La、Ce、Pr、Sm的最佳掺杂量分别为1.5 wt%、0.5 wt%、0.2 wt%、0.2 wt%。在最佳掺杂量下,对每种稀土元素掺杂的二氧化钛进行光催化降解甲基橙稳定性能研究,结果表明,稀土元素掺杂的TiO_2样品光催化降解甲基橙的稳定性程度依次为:Sm-TiO_2Pr-TiO_2Ce-TiO_2TiO_2La-TiO_2。
[Abstract]:With the acceleration of industrialization process and the increasing number of population, the safety of water resources has become a problem that people pay more attention to. However, serious water pollution aggravates people's demand for water resources. Photocatalytic degradation of pollutants in water has become an effective method to solve water pollution because it is in chemical stability, market price, and light. Titanium dioxide semiconductors have attracted wide attention from many aspects, such as catalytic performance and environmental protection. However, the absorbable spectral range of titanium dioxide is narrow, the utilization rate of solar light and the light quantum efficiency are low. These all restrict the wide application of titanium dioxide in practice. Doping modified titanium dioxide can widen it. The light response range and the enhancement of the light quantum efficiency are very effective measures to improve the photocatalytic activity of titanium dioxide. The aim of this paper is to explore the optimal process of obtaining high photocatalytic activity of titanium dioxide by sol-gel method, and to improve the photocatalytic performance by adjusting the band gap of titanium dioxide to improve the photocatalytic performance. At the same time, the rare earth element doping to two is explored. The influence of the crystal structure, photochemical properties and photocatalytic activity of titanium oxide. The main conclusions are as follows: (1) powder titanium dioxide was prepared by sol-gel method with four n-butyl titanate as raw material, ethanol as solvent and glacial acetic acid as chelating agent. The gelation time and photocatalytic degradation of methyl orange by the conditions of ethanol, water, glacial acetic acid and pH were discussed. The best preparation conditions are: n (C_2H_5O H) /n (Ti (OBu) 4) =15; n (H_2O) /n (Ti (OBu)); 500 degrees centigrade calcined 1 (2) using sol-gel method and roasting 1 at 600 centigrade to prepare a bar like structure. TiO2, compared with spherical titanium dioxide, the energy gap of TiO2 decreased obviously. The effect of initial concentration of methyl orange and the dosage of catalyst on the degradation rate of methyl orange was investigated. Rod like titanium dioxide showed excellent photocatalytic performance: the initial concentration of the catalyst was 0.4 g dm~ (-3), and the initial concentration of methyl orange was 10 mg. Dm~ (- 3) after light 1H, the degradation rate of rod like titanium dioxide to methyl orange reached 95.7%, and the degradation rate of spherical titanium dioxide to methyl orange was only 74%. (3). This paper studied the titanium dioxide doped with four rare earth elements, La, Ce, Pr, Sm. The experimental results showed that the doping of La, Ce, Pr and Sm enhanced the transformation of titanium dioxide from anatase to rutile. The temperature is changed, and the absorption band edge appears in varying degrees of red shift. Doping elements and doping amount have great influence on the photocatalytic activity of titanium dioxide. The doping of rare earth elements can obviously improve the photocatalytic activity of titanium dioxide, and there is the best doping amount. The optimum doping amount of La, Ce, Pr, Sm is 1.5 wt%, 0.5 wt%, 0.2 wt%, 0.2 wt%., respectively. Under the optimum doping amount, the stability of methyl orange by photocatalytic degradation of each rare earth doped titanium dioxide was studied. The results showed that the stability degree of photocatalytic degradation of methyl orange by TiO_2 samples doped by rare earth elements was in turn: Sm-TiO_2Pr-TiO_2Ce-TiO_2TiO_2La-TiO_2.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.11;O643.36

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