發(fā)布時(shí)間：2018-06-22 04:44

  本文選題：光催化 + 二氧化鈦　； 參考：《湖南大學(xué)》2015年碩士論文

【摘要】：隨著工業(yè)化進(jìn)程的加速,人口數(shù)量不斷攀升,水資源安全成為人們?nèi)找骊P(guān)注的問題,然而嚴(yán)重的水體污染加劇了人們對水資源的需求。光催化降解水中污染物已經(jīng)成為一種有效的解決水體污染的方法。因?yàn)樗诨瘜W(xué)穩(wěn)定性,市場價(jià)格,光催化性能和環(huán)境保護(hù)等多方面優(yōu)勢明顯,二氧化鈦半導(dǎo)體受到了研究者們的廣泛關(guān)注。然而,二氧化鈦可吸收的光譜范圍狹窄,太陽光利用率和光量子效率低,這些都限制了二氧化鈦在實(shí)際中的廣泛應(yīng)用。摻雜改性二氧化鈦可以拓寬其光響應(yīng)范圍,提高光量子效率,是提高二氧化鈦光催化活性非常有效的措施。本論文旨在探究溶膠-凝膠法獲取具有高光催化活性二氧化鈦的最優(yōu)工藝;通過調(diào)整形貌窄化二氧化鈦的禁帶,提高光催化性能;同時(shí)探究了稀土元素?fù)诫s對二氧化鈦晶體結(jié)構(gòu)、光化學(xué)性能及光催化活性的影響。主要結(jié)論如下所示:(1)以鈦酸四正丁酯為原料,乙醇為溶劑,冰醋酸為螯合劑,采用溶膠-凝膠法制備了粉體二氧化鈦。探討了乙醇、水、冰醋酸和pH等條件對凝膠時(shí)間和光催化降解甲基橙性能的影響。同時(shí)探討了焙燒溫度和焙燒時(shí)間對二氧化鈦光催化活性的影響。最佳制備條件為: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℃焙燒1 h。(2)采用溶膠-凝膠法,在600℃條件下焙燒1 h制備了棒狀結(jié)構(gòu)的二氧化鈦,與球狀二氧化鈦相比,棒狀二氧化鈦的能隙值明顯減小。實(shí)驗(yàn)探討了甲基橙初始濃度和催化劑投加量對甲基橙降解率的影響。棒狀二氧化鈦表現(xiàn)出了優(yōu)異的光催化性能:當(dāng)催化劑濃度為0.4 g·dm~(-3),甲基橙初始濃度為10 mg·dm~(-3)時(shí),光照1h后,棒狀二氧化鈦對甲基橙的降解率達(dá)到了95.7%,而球狀二氧化鈦對甲基橙的降解率只有74%。(3)本文對La、Ce、Pr、Sm四種稀土元素?fù)诫s的二氧化鈦進(jìn)行研究,實(shí)驗(yàn)結(jié)果表明La、Ce、Pr、Sm的摻雜能提高二氧化鈦由銳鈦礦相向金紅石相轉(zhuǎn)變的溫度,并使吸收帶邊出現(xiàn)不同程度的紅移。摻雜元素和摻雜量對二氧化鈦的光催化活性影響很大。稀土元素的摻雜可以明顯提高二氧化鈦的光催化活性,并且存在最佳摻雜量,La、Ce、Pr、Sm的最佳摻雜量分別為1.5 wt%、0.5 wt%、0.2 wt%、0.2 wt%。在最佳摻雜量下,對每種稀土元素?fù)诫s的二氧化鈦進(jìn)行光催化降解甲基橙穩(wěn)定性能研究,結(jié)果表明,稀土元素?fù)诫s的TiO_2樣品光催化降解甲基橙的穩(wěn)定性程度依次為: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.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ134.11;O643.36

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