【作者】 邓安平；

【导师】 黄应平；

【作者基本信息】 三峡大学 ， 生态学， 2010， 硕士

【摘要】 纳米TiO₂因其具有粒径小、比表面积大、分散性好、实际应用中无二次污染等优点而备受关注,纳米TiO₂的制备、性能及应用成为国内外学者研究的热点。本文研究了水热（溶剂热）制备条件对纳米TiO₂微观结构的影响及其在光照射下对有毒有机污染物降解的催化特性,探讨了其制备条件对纳米TiO₂晶型、形貌的影响,比较了不同条件下制备TiO₂的催化性能,分析了TiO₂的光谱学性质,并通过跟踪分析不同光催化体系过程中主要活性物种·OH和H2O₂的变化,探讨了光催化反应作用机理。1利用溶剂法在不同溶剂介质（水,NaOH溶液、乙醇、OP乳化剂、二乙醇胺）条件下制备了纳米TiO₂。考察了以不同溶剂及溶剂比例,NaOH溶液浓度、温度等条件下对TiO₂晶体微观结构的影响,通过在紫外光照射下对有机染料的光催化降解性能试验,分析了不同微观结构纳米TiO₂的光谱学特性。2低温溶剂制备了TiO₂粉末,X射线衍射仪（XRD）、比表面积及孔径分析仪（BET）和透射电镜（TEM）对TiO₂进行了初步表征。表明:纳米TiO₂主要为锐钛矿相（含板钛矿相（121））,比表面积为106.2m2/g。在紫外光（λ≤387nm）照射条件下,以有机染料罗丹明B（rhodamine B, RhB）和无色小分子2,4-二氯苯酚（2,4- dichlorophenol , 2,4-DCP）的光催化降解试验为探针反应,研究了催化剂的催化活性。表明低温（50℃）下制备的TiO₂粉末具有较高光催化活性,对RhB和2,4-DCP有较好的降解效果。通过紫外-可见光谱（UV-vis）、红外光谱（FTIR）和总有机碳（TOC）测定,发现TiO₂/UV体系能使RhB和2,4-DCP发生有效的降解,反应5h后RhB和7h后2,4-DCP的矿化率分别达到81.2%和86.8%。同时,采用辣根过氧化物酶（POD）、N,N-二乙基对苯二胺（DPD）分光光度法和苯甲酸荧光光度法分别测定了在降解过程中H2O₂和羟基自由基（·OH）的变化,表明TiO₂光催化机理涉及到·OH历程。3以无定形TiO₂沉淀为前驱体,在水热条件下制备了含板钛矿型TiO₂纳米颗粒,考察了水热反应的温度和时间等因素对含板钛矿型TiO₂光催化活性的影响。采用XRD、TEM对制备的TiO₂进行初步表征,并结合光催化（λ≤387 nm）降解有机染料的光活性探针反应,结果表明水热温度为150℃,时间为24 h时可制得具有较高光催化活性含板钛矿的纳米TiO₂。光催化试验中研究了染料酸性桃红（Sulforhodmine B,SRB）的褪色及降解情况,并对中间产物H2O₂和·OH进行跟踪测定,表明含板钛矿型TiO₂的光催化主要涉及·OH氧化历程。4以正辛胺（n-octyl amine, OA）为模板通过溶胶—沉淀法制备了TiO₂@SiO₂纳米球,通过TEM、XRD、电化学性能及有机染料酸性桃红（Sulforhodamine B, SRB）、罗丹明B（rhodamine B, RhB）的光催化探针反应,探讨了TiO₂@SiO₂纳米球制备过程中酸度及煅烧温度对其形貌、晶型及光催化性能的影响。结果表明:在反应温度50℃、1mol/L HCl的介质条件和550℃煅烧温度的条件下制得的TiO₂@SiO₂粉末主要为比电容最高,分散度好的锐钛矿型纳米球;试验通过自旋共振（Electron Spin Resonance, ESR）、分光光度法、红外光谱及总有机碳分析探讨了该催化剂在紫外光下催化降解有机染料SRB及RhB及小分子2,4-DCP的光催化反应特性、矿化氧化效果及降解机理。实验表明:其光催化效果与商业P25相近,对有机污染物有较好的矿化效果,降解过程主要涉及·OH氧化机理。5以钛酸四丁酯和硝酸铈以及碘等为原料,利用溶胶-凝胶法,于450℃温度下煅烧制备了不同掺杂比例的TiO₂催化剂。采用XPS、XRD、TEM以及TG等对催化剂进行了表征及光学性质的测试。结果表明:共掺杂后TiO₂的禁带宽度从3.03eV降低到2.51eV,TiO₂纳米尺寸为13nm左右,主要为锐钛矿相,碘和铈元素掺杂到TiO₂晶格间,催化剂均有良好的热稳定性,热失重小于2%。以降解RhB为探针反应,对碘铈共掺杂纳米TiO₂进行了优化,并对光催化反应体系中氧化物种进行跟踪测定,发现掺杂后可见光下TiO₂降解动力学常数提高了6倍,且光催化过程涉及穴氧化机制。更多还原

【Abstract】 Nano-TiO₂ particle has drawn more and more people’s attention owing to the smaller particle size, the larger surface area, good dispersion and no pollution properties. Preparation and development of nano-TiO₂ has become a central issue of the material science and nanotechnology both here and abroad. This paper was studied the low-temperature hydrothermal （solvent-thermal ） under the micro-structure of nano-TiO₂, as well as its application in light irradiation degradation of organic pollutants, and analyzed the spectral properties of TiO₂ and photocatalytic mechanism.1 Nano-TiO₂ was prepared in the different solvents of H2O, NaOH, CH3CH2OH, OP emulsifier and diethanolamine. The effects of solvent and temperature on the microstructure of TiO₂ were investigated. Morevover, the degradation of organic dyes under ultraviolet light by nano-TiO₂ and the spectroscopy properties of nano-TiO₂ with various structures were analysed.2 TiO₂ particles were prepared under low temperature by solvothermal method. XRD, BET surface area and pore size analyzer and TEM were carried out to characterise TiO₂. The results showed that the cannular frame of TiO₂ was mainly anatase phase with the existence of brookite phase （121） and specific surface area was 106.2m2/g. The photocatalytic degradation of organic dye rhodamine B （RhB） and colorless small molecule 2,4-DCP under UV （λ≤387nm） were used as probe reactions to evaluate the photocatalytic activity of TiO₂. It was indicated that TiO₂ prepared under low temperature （50℃） showed good photocatalytic activity in the degradation of RhB and 2,4-DCP in view of the analysis of UV-visible spectroscopy, infrared spectroscopy （FTIR） and total organic carbon. In the TiO₂/UV system, the mineralized rates of RhB and 2,4-DCP were 81.2% （5h later） and 86.8% （7h later）, respectively. The concentration of H2O₂ was determined using horseradish peroxidase （POD） and N, N-diethyl-p-phenylenediamine （DPD） spectrophotometry. The content of·OH was detected by fluorescence spectrophotometry of benzoic acid. The experiment indicated that photocatalytic degradation of TiO₂ mainly involved·OH mechanism.3 Brookite titania particles were prepared from a precursor of TiO₂ by hydrothermal method. The effects of the reaction temperature and the reaction time on the photocatalytic activity of the brookite titania were studied. The TiO₂ samples were characterized by XRD and TEM. Photocatalytic degradation of organic dye under UV light （λ≤387 nm） was used as the probe reaction to evaluate the properties of the optimum TiO₂. It was indicated that TiO₂ prepared under 150℃for 24h with the existence of brookite phase had a high photocatalytic activity. The discoloration and degradation of sulforhodamin B （SRB） were tracked, and the produced intermediate H2O₂ and·OH were determined during the photocatalytic experiments. It was indicated that photocatalytic degradation of brookite TiO₂ mainly involved the·OH mechanism. Brookite TiO₂ also exhibited the potential of application in photocatalysis.4 TiO₂@SiO₂ nanosphere powders were prepared using n-octylamine as a template by the sol-precipitation method. The effects of reaction acidity and calcination temperature on morphology, crystal and photoelectric properties of TiO₂@SiO₂ nanosphere powders were researched through XRD, TEM, electrochemical properties and photocatalytic degradation which used organic dyes as probe reaction. It was indicated that TiO₂@SiO₂ nanosphere powders prepared at the condition of reaction temperature 50℃, medium 1mol/L of HCl and calcination temperature 550℃were mostly anatase nanospheres with the highest dispersity and specific capacitance. The photocatalytic degradation properties of organic dyes and small molecules, the effect of mineralization and the mechanism of degradation were studied by Electron Spin Resonance （ESR）, Spectrophotometry, IR and TOC. It was indicated that the photocatalytic effect of TiO₂@SiO₂ nanosphere powders were similar to that of business P25 and the photocatalytic process mainly involved·OH mechanism.5 Titania of different doping amounts was prepared by sol-gel method, which used tetrabutyl titanate, cerium nitrate and iodine as materials and were calcined at 450℃. XPS, XRD, TEM and thermal gravimetric analysis （TG） were carried out to characterise the optical properties of the catalysts. It was indicated that the band gap of doped-TiO₂ decreased from 3.03eV to 2.51eV and the size of it was 13nm. The doped-TiO₂ which was mainly anatase with iodine and Ce doped in the crystal lattice of TiO₂ had good thermal stability and TG was less than 2%. Nano-TiO₂ doped with iodine and cerium had been optimized in the degradation of RhB and the oxidizing species in photocatalytic reaction system was measured. It was found that the degradation rate of doped TiO₂ raised to six times under visible light, and photocatalytic mechanism referred to the hole oxidation.更多还原