【作者】 陈捷；

【导师】 熊德琪； 冯威；

【作者基本信息】 大连海事大学 ， 环境科学， 2008， 博士

【摘要】 本文利用钠基膨润土作为载体,采用酸性溶胶法制备TiO₂柱撑膨润土材料和掺杂金属离子的TiO₂柱撑膨润土复合材料,利用TEM、XRD、FT-IR、TG-DTA、BET、XPS、DRS等手段对材料的形貌、结构和组成进行了表征,并研究了其吸附和光催化协同作用降解染料分子的影响因素和不同种类染料分子降解的机制与途径。现将结果归纳如下:（1）制备了TiO₂柱撑膨润土材料,考察了焙烧温度和TiO₂含量对其结构和性能的影响。TiO₂柱撑膨润土复合材料具有良好的层状结构,TiO₂以锐钛矿的形式存在于膨润土的层间。柱撑后的复合材料的层间距、比表面积、热稳定性以及吸附和光催化性能均得以提高。473 K时焙烧,TiO₂含量为50%时的TiO₂柱撑膨润土具有最佳的吸附性能和光催化活性。（2）制备了掺杂不同金属离子的TiO₂柱撑膨润土,掺杂的金属离子以非晶态形式存在,金属离子的掺杂对层间距几乎没有影响,与TiO₂柱撑膨润土相比较,掺杂金属离子后BET比表面积略有增加。其吸附性能和光催化活性由强至弱的顺序为:Fe-Ti-Na-MMT＞Y-Ti-Na-MMT＞La-Ti-Na-MMT＞Zn-Ti-Na-MMT＞Ni-Ti-Na-MMT＞Cu-Ti-Na-MMT＞Ti-Na-MMT。不同金属离子掺杂作用的变化规律与离子带电电荷数和半径的比值的变化规律基本相同。金属钇离子掺杂量为1.5%时制备的复合材料具有较高的吸附和光催化性能。（3）研究了TiO₂柱撑膨润土材料吸附和光催化降解染料的分子动力学规律。复合材料吸附甲基橙的动力学行为与Bangham和Langmuir方程所述规律基本符合。Freundlich吸附等温方程和Langmuir吸附等温方程都能很好的描述此类材料对甲基橙的吸附性能。TiO₂柱撑膨润土复合材料光催化降解甲基橙表现为一级反应,遵循Langmuir-Hinshelwood模式。适当的pH、甲基橙溶液初始浓度和适量的H₂O₂可以加速光催化氧化反应速率。不同结构的染料分子被吸附和光催化降解由易至难的顺序为:罗丹明B＞甲基橙＞刚果红＞活性艳蓝。（4）研究了掺杂金属钇离子的TiO₂柱撑膨润土降解不同结构染料的降解机理和途径。结果表明,染料吸附在复合材料表面,经历了一系列光氧化反应,导致溶液的脱色和以芳香酸、脂肪酸为主的中间产物的生成,这些物质进一步氧化成小分子量的分子,最终完全矿化为CO₂和无机离子,如NO₃^-、SO₄^2-和NH₄⁺。不同结构的染料分子在光催化过程中经历了不同的降解途径。TiO₂柱撑膨润土复合材料降解染料的过程存在着吸附和光催化的协同作用,吸附能力的增强可以提高光催化降解速率,同时建立了吸附和光催化协同作用反应模型。更多还原

【Abstract】 In this paper,TiO₂-pillared bentonite and TiO₂-pillared bentonite with transitional metal ions doping are synthesized by acid catalyzed sol method using bentonite as the carriers.The morph ology,structure and composition of the composites are characterized by TEM,XRD,FT-IR,TG-DTA,BET、XPS and DRS.The factors,which affect the synergistic effect on adsorptive and photocatalytic degradation of dyes,and the mechanism and pathways of degradation of dyes with different structure,are also investigated.Here,reslutes are summed up as follows:（1） TiO₂-pillared bentonite is prepared,and the influence of calcination temperature and the content of TiO₂ on the structure and degradated activity are studied.It has been found that TiO₂-pillared bentonite has the best samdwich and TiO₂ nanoparticles,the crystal type of which is Anatase,are distributed into the layers of bentonite.The d001 basal spacings,BET special surface area,the thermal stability and adsorptive and photocatalytic activity of composites are all enhanced compared with bentonite.Results indicate that TiO₂-pillared bentonite with 50%TiO₂ content,which is calcinated at 473K, exhibite the highest adsorptive and photocatalytic activity.（2） TiO₂-pillared bentonite composites with different metal ions doping are prepared. Results show that doped metal ions lie in the shape of noncrystal,which have no effect on the d001 basal spacings.Compared with TiO₂-pillared bentonite,BET special surface area has been increased slightly.The adsorptive and photocatalytic activity change from high to weak according to the regularity as follows:Fe-Ti-Na-MMT＞Y-Ti-Na-MMT＞La-Ti-Na-MMT＞Zn-Ti-Na-MMT＞Ni-Ti-Na-MMT＞Cu-Ti-Na-MMT＞Ti-Na-MMT,which is similar with the change regularity of the ratio between ionic charges and ionic radius.For Y³⁺-doped TiO₂-pillared bentonite,1.5%Y³⁺ content have the highest adsorptive and photocatalytic activity.（3） Kinetic model of adsorption and photocatalysis is investigated using Y³⁺-doped TiO₂-pillared bentonite in dyes solution.Adsorptive kinetic analyses indicate that the process of adsorption accords with Bangham and Langmuir equation.Meanwhile,the adsorptive capability of the composites can be well described using Freundlich and Langmuir isotherm adsorption equation.Photocatalytic kinetic analyses indicate that the photodegradation rates of methyl orange can usually be approximated as pseudo-first-order kinetic,according to the Langmuir-Hinshelwood model.Several factors such as pH,substrate concention,the presence of H₂O₂ and the structure of dye molecule,which affect the efficiency of adsorptive and photocatalytic degradation,are discussed.It has been found that the efficiency of degradated dyes can be enhanced by appropriate pH,substrate concention and H₂O₂ additive.The regularity of adsorptive and photocatalytic degradation of dyes with different structure is as follows:rhodamine B＞methyl orange＞congo red＞reactive blue.（4） The photocatalytic degradation of dyes with different structure has been investigated with the use of Y³⁺-doped TiO₂-pillared bentonite.It has been found that dyes adsorbs on the composites and undergoes a series of oxidation stepds,which lead to decolorization and formation of a number of intermediates,mainly aromatic and aliphatic acids.These molecules are further oxidized toward compounds of progressively lower molecule weight and,eventually,to CO₂ and inorganic ions,such as sulfate,nitrate and ammonium ions.There is a synergistic effect on the process of adsorption and photocatalysis using the composites,and the increase of adsorptive capabilitiy will enhance the photocatalytic activity.The reaction model of adsorption and photocatalysis is built for the first time.更多还原