【作者】 徐蕾；

【导师】 袁星；

【作者基本信息】 东北师范大学 ， 环境科学， 2010， 博士

【摘要】 本论文针对目前TiO2光催化剂存在的量子效率低、可见光利用率低和回收困难等问题,分别制备了多酸-二氧化钛(H3PW12O40/TiO2)及银掺杂多酸-二氧化钛(H3PW12O40/Ag-TiO2)复合光催化材料,对其结构、形貌、光吸收特性和表面物理化学性质进行了表征,系统研究了两种复合材料的光催化行为,探讨了H3PW12O40/TiO2光催化降解邻苯二甲酸二乙酯(DEP)和邻苯二甲酸二丁酯(DBP)的机理。具体研究如下：1.利用溶胶-凝胶结合程序升温方法,制备了具有较高光催化活性的H3PW12O40/TiO2复合材料。通过电感耦合等离子体-原子发射光谱、透射电子显微镜、X-射线粉末衍射、紫外-可见漫反射光谱和X-射线光电子能谱对该复合材料的组成和结构、光吸收性质、形貌以及表面物理化学性质进行了表征；通过在模拟太阳光条件下降解水中酞酸酯类化合物(PAEs)对其光催化活性进行了评价；测定了溶液pH值对光催化降解效率的影响。结果表明：复合材料中活性组分H3PW12O40的基本骨架结构未发生改变,而且与TiO2网络间存在较强的化学作用,母体TiO2以锐钛矿晶型为主；H3PW12O40/TiO2具有微孔-介孔双重孔径及较大的BET比表面积；H3PW12O40/TiO2光催化剂的活性随着H3PW12O40的担载量(0%-19.8%)增加而增强,并且明显好于纯TiO2; H3PW12O40/TiO2复合材料光催化降解PAEs的效率由大到小的顺序是DBP>DEP>DMP;中性或碱性条件可以促进H3PW12O40/TiO2对DEP的光催化降解。2.采用高效液相色谱-质谱和离子色谱对H3PW12O40/TiO2复合材料在模拟太阳光条件下光催化降解DEP和DBP的中间产物进行了分析,测定了降解过程中TOC的变化。结果表明：DEP可以通过三条路径实现矿化,降解的主要中间产物有羟基化的邻苯二甲酸二乙酯、邻苯二甲酸、二羟基苯甲酸、马来酸酐和苯酚等化合物；DBP可通过四条路径实现矿化,降解的主要中间产物有羟基化的邻苯二甲酸二丁酯、羟基邻苯二甲酸、苯甲酸丁酯等化合物,两者的中间产物均可进一步降解生成甲酸、乙酸和丁二酸等小分子酸,最后生成CO2和H2O。3.采用溶胶-凝胶结合程序升温溶剂热处理方法制备了H3PW12O40和金属Ag共掺杂的TiO2复合材料H3PW12O40/Ag-TiO2。通过电感耦合等离子体-原子发射光谱、透射电子显微镜、X-射线粉末衍射、紫外-可见漫反射光谱和X-射线光电子能谱对复合材料的组成和结构、光吸收性质、形貌以及表面物理化学性质进行了表征；通过在模拟太阳光条件下降解DEP和磺胺甲恶唑(SMZ)对其光催化活性进行了评价。结果表明：该复合材料具有锐钛矿相结构,金属银以单质形式存在；复合材料不仅在200-380 nm处有强烈吸收,而且在400-600 nm之间也有明显的光吸收；H3PW12O40/Ag-TiO2具有微孔(0.45 nm)和介孔(4.2 nm)双重孔径；BET比表面积较H3PW12O40/TiO2略小；不同光催化剂的活性顺序是H3PW12O40/Ag-TiO2>Ag/TiO2> H3PW12O40/TiO2>TiO2。更多还原

【Abstract】 In this thesis, we focus on the vital scientific difficult problem in the TiO2 photocatalytic technology such as the lower quantum efficiency, the lower activity under visible light, and difficult separation of powder catalyst from catalysed system. H3PW12O40/TiO2 and H3PW12O40/Ag-TiO2 were prepared and well-characterized, and their catalytic activities were systematically studied. The photocatalytic degradates mechanism of DEP and DBP were studied.New and efficient heterogeneous photocatalytic material, H3PW12O40/TiO2 with anatase crystalline phase, was prepared by combination of the methods of sol-gel and hydrothermal treatment at a lower temperature. Composition, structure, optical absorption property, physicochemical properties, and surface morphology of the composite were characterized by test technologies. Under simulated-sunlight irradiation, we studied the photocatalysic activities of H3PW12O/TiO2 for phthalate acid esters (PAEs) in aqua, and tested the effects of the pH value of solution on photocatalysic degration efficiency. Research results indicated that the starting Keggin structure of H3PW12O40 in the as-synthesized composites was still remained intactly after immobilization of the unit into the TiO2 network. Hydrogen bonding and chemical interactions between the unit and the anatase network existed in the composite. Moreover, the BET area of this material with dual-pore structures, micro-and meso-porosity, was increased obviously. Under simulated-sunlight the photocatalytic activity of the composites was evaluated by degradation of aqueous phthalate esters. The results showed that the photocatalytic activity of H3PW12O40/TiO2 was higher than that of pure TiO2, In addition, the photocatalytic activity of H3PW12O40/TiO2 monotonically increased along of loadings H3PW12O40 from 0 to 19.8%. Under the simulated-sunlight irradiation, the degradation efficiency of H3PW12O40/TiO2-19.8 for PAEs was determined in sequence DBP>DEP>DMP. It is also observed that pH variations influence the photocatalytic activity of the H3PW12O40/TiO2 composite, and neuter or alkaline conditions can promote the photocatalytic degradation of H3PW12O40/TiO2 for DEP.HPLC-MS and IC were used to detect and analysis the intermediates generated during the DEP and DBP degradation process. Tests of TOC also were carried out. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of DEP and DBP were put forward. DEP can realize mineralization by three path, and the main products among the degradation process is consist of hydroxyl DEP, phthalic acid,2-hydroxyl benzoic acid, maleic anhydride and phenol, etc. DBP can realize mineralization by four path, and the main products among the degradation process is consist of hydroxyl DBP, hydroxyl phthalic acid, butyl acrylate acid, etc. Both the intermediates generate formate, succinic acid, and acetic acid, etc. through degradation, further CO2 and H2O.H3PW12O40/Ag-TiO2 nanocomposites, H3PW12O40 and Ag co-doped TiO2 nanocomposites with enhanced photocatalytic activity, was successfully prepared by combination of the methods of sol-gel and hydrothermal treatment at a lower temperature. Composition, structure, optical absorption property, physicochemical properties, and surface morphology of the composite were characterized by test technologies. It was obsreved that the H3PW12O40/Ag-TiO2 show anatase crystalline phase, and metallic Ag particles well distributed on the surface. Also it was shown that the maximum absorption of composite material after introduction of Ag ion occured a obvious small shift toward longer wavelengths, and appeared not only at 200-380 nm but also at 400-600 nm; Compared with pure TiO2, the BET area of composite material with dual-pore structures, micro-and meso-porosity (0.45 nm and 4.2 nm) was slightly decreased. The photocatalysic activities of H3PW12O40/Ag-TiO2 was tested by degradation of aqueous DEP and Sulfamethoxazole (SMZ) under simulated-sunlight irradiation. The results showed that the photocatalytic activity of H3PW12O40/TiO2 was higher than that of pure TiO2. The photocatalytic activity of different composites are arranged as follows:H3PW12O40/Ag-TiO2>Ag/TiO2>H3PW12O40/TiO2>TiO2. The reasons of this enhanced photocatalytic activity were discussed logically.更多还原