【作者】 于书平；

【导师】 古国榜； 赵进才；

【作者基本信息】 华南理工大学 ， 环境工程， 2004， 博士

【摘要】 有毒难生化有机染料废水的治理因缺乏有效的处理方法成为了水处理领域的难点,对人类和环境造成了极大的危害。本论文对制备的掺杂钒和铅二氧化钛薄膜进行了表征和光催化研究。在此基础上,制备了具有更高的析氧电位和一定催化活性的二氧化铅电极,并进行了结构表征和可见光光电催化降解RhB的研究,提出可见光照射下的光电降解机理。 采用溶胶—凝胶法在玻璃表面制备钒离子掺杂的TiO₂薄膜（VD_x、VT_x,VB_x）,和铅离子掺杂的TiO₂薄膜（PbD_x、PbT_x）。通过XRD分析表明,晶型均为锐钛矿型。在同样掺杂摩尔比下,掺杂方式不同,薄膜所表现出的透过率也不相同。实验发现,通过VD_x/PbD_x方式制备的非均匀掺杂的TiO₂薄膜具有更高的光催化活性,掺杂摩尔比存在一个最佳值。以光催化降解甲基橙水溶液的探针反应,结果表明:V/Ti摩尔比为1.0%的非均匀掺钒的TiO₂薄膜光催化降解甲基橙的表观速率常数是纯TiO₂的2.3倍。Pb/Ti摩尔比为0.5%的非均匀掺铅的TiO₂薄膜光催化降解甲基橙的表观速率常数是纯TiO₂的2.52倍。 分析表明,掺杂金属离子在薄膜内部富集时,作为TiO₂薄膜表面光生电子和空穴的捕获位或复合中心的机会也大大减少,但掺杂金属离子在TiO₂薄膜内部的分布则分离了光生电子和空穴,增强了光生电子与空穴的分离效率。反而延长了激发电子的寿命,抑制了载流子的复合,同时电荷转移电阻变小,电子更易于转移,光电流响应好。从而提高了TiO₂薄膜的光催化活性。 提出较为理想的掺杂是,掺杂物离子在TiO₂薄膜近表面处捕获光生电子或空穴,随后,被捕获的电子或空穴迁移到TiO₂薄膜表面参与光催化反应。 采用恒电位电沉积工艺制备了具有更高析氧过电位和一定催化活性的二氧化铅电极,结构表征结果显示PbO₂电极为β与α晶型共存。薄膜表面平整,致密性好,厚度约为0.6μm。电极在可见光区有吸收,因此对太阳光的利用率较高。光电催化过程可完全在可见光下进行。 通过XPS分析表明,PbO₂膜表面Pb价态为+4价。电化学阻抗分析表明,在可见光光照下PbO₂的电荷转移电阻变小,具有良好的光电性能。 研究了罗丹明B（RhB）在PbO₂表面上的吸附对光电催化降解的影响,根据实验结果,得出Langmuir吸附等温方程Ce/q_e=1.30992X+30.8591。红外光谱分析表明,PbO₂对RhB有吸附作用。 以RhB的降解反应为探针反应,探讨了光催化技术与电催化技术联合对RhB的降解协同效果。结果表明,在本实验条件RhB的光电催化降解协同效应因子f更多还原

【Abstract】 The treatment of toxic and dye wastewater is one of the biggest technical difficulties due to the lack of highly effective solution, which has cause severe hazard both to the humankind and our environment. In this paper, a novel TiO₂ thin films modified by non-uniform doping was adopted for the photocatalytic degradation. Various characterization techniques were used to research the mechanism of photocatalytic degradation. At the same time, PbO₂ electrode was prepared, which had the higher oxygen potential and good photocatalytic activity. And the structure was characteristic, and studied degraddtion of RhB under visible light. The mechanism of RhB by photoelectrocatalytic degradation was discussed.Sol-Gel method was used to prepare the novel TiO₂ thin films modified by vanadium ion doped （VD_x VT_x, VB_x） and lead ion doped （PbD_x PbT_x） on the glasses. The crystal of the films was anatase by XRD analysis. The transmittances of each film were different on the same concentration of different doped method. It was observed that the non-uniform doped TiO₂ films modified by VD_x/PbD_x method had higher photocatalytic activity and best rate of molar. The photocatalytic degradation of methyl orange is used as the probed reaction. The result is that the apparent rate constant k of non-uniform doped vanadium ion TiO₂ films was 2.3 times that of pure TiO₂ films whose the rate molar of V/Ti is 1.0%. And the apparent rate constant k of non-uniform doped lead ion TiO₂ films was 2.52 times that of pure TiO₂ films whose the rate molar of Pb/Ti is 0.5%.The result showed that when the doped metal ion clustered in the inner of thin film, the effective capture or recombination chance of electron-hole pair was decreased, but the separation of electron-hole pair was enhanced. The electron life was prolonged and the recombination chance of electron-hole pair was restrained, so the resistance of charge movement turned small and the electron was easy to transfer. The ideal doping effect was that the ion doptant captured the electron/hole near the surface of TiO₂ thin film, then the captured electron/hole transferred to the surface to had photocatalytic reaction.Constant potential technique was used to electrodeposit PbO₂ films with higher oxygen potential and good photocatalytic activity. The crystals included both β and α . The surface was flat and the thickness was about 0.6 μ m. The electrode hadabsorption in visible light region, so it can have photoelectrocatalytic degradation under the visible light. XPS analysis showed that the Lead of the film surface of PbO2 is only +4 valency. The EIS showed that the charge transfer resistance of PbO2 turned to small under the visible light.The photoelectrocatalytic degradation of RhB is influenced by the adsorption of RhB on the PbO2 surface. The Langmuir adsorption isotherm equation of RhB on the PbO2 surface Ce/qe=1.30992X+30.8591 is put forward on the basis of the experimental results.The synergetic effect of the combination of photo catalytic and electric technology was discussed with RhB. It was observed that the synergetic effect performed well and the promoting factor f was 741%.The influence factors on the photoelectrocatalytic degradation of RhB were investigated. The degradation of RhB is more efficient in acidic medium. And it performed the best in the electrolyte of NaCl. The degradation efficiency of RhB increased with a increase of the potential. The degradation efficiency of RhB increased greatly when H2O2 was added.The mechanism of photoelectrocatalytic degradation of RhB was proposed. The reaction leads mainly to N-de-alkylation of the RhB chromophore skeleton. The removal of COD with reaction times followed the first reaction kinetics. The reaction kinetics constant of COD removal was 0.00359mm’1. The new products were DER^ EER^ DR> ER and R. The products were all experience a process of up then down except the original dye. It was showed that the process of producing and degradation.With PbO2 as the photoelectric catalyst, the photoreaction leads mainly to N-dea lkylation of the dye. By contrast, cleavage of the whole conjugated chromophore stru cture predominates in the electric chemistry oxidation.更多还原