【作者】 李静；

【导师】 张培新； 刘剑洪；

【作者基本信息】 广西大学 ， 应用化学， 2004， 硕士

【摘要】 采用均匀沉淀法，以硫酸氧钛为主原料，尿素为沉淀剂宿主制备出8～30nm的TiO₂，采用X射线衍射（XRD）、透射电子显微镜（TEM）、差热—热重（DTA-TG）等分析测试手段研究了反应温度、反应时间、反应物配比、反应物浓度，煅烧时间以及煅烧温度等因素对纳米TiO₂的粒径、形貌、晶型转变的影响，结果表明：纳米TiO₂的收率随反应温度、反应物配比、反应时间的增大而增加，随反应浓度的增大减小；TiO₂的粒径随反应温度、反应浓度、煅烧温度、煅烧时间的增大而增大；TiO₂的晶型随煅烧温度的升高，由无定型转变为锐钛矿再向金红石型转变。通过正交化实验设计得出制备纳米TiO₂的最佳工艺条件为：反应温度：90℃；[TiO²⁺]浓度：0.8mol／l；反应时间：4h；TiOSO₄／CO（NH₂）₂：1：3。通过DTA对纳米TiO₂的晶型转变进行研究，得出了在最佳工艺条件下制备出的纳米TiO₂的晶型转化温度，在470℃左右由无定型转变为锐钛矿型，在830℃左右开始由锐钛矿型向金红石型转变，这与XRD的结果完全一致。 在不同条件下对工业级TiO₂和合成的纳米TiO₂进行表面Si包覆，采用透射电子显微镜（TEM）、X光电子能谱（XPS）、X荧光光谱（XRF）等测试手段分别对包覆颗粒的表面形貌、表面组成、成膜机理、颗粒界面的化学键合进行了研究，结果表明TiO₂表面元素的Si元素是以化学键结合于TiO₂颗粒表面的，形成Ti—O—Si键；得出包覆的最佳反应条件：1、工业级TiO₂：反应温度：85℃；反应时间：5h；C_Na2SiO3：0.5mol／l；反应pH：9.5；C_TiO2：200g/l；2、纳米TiO₂：反应温度：90℃；反应时间：1h；C_Na2SiO3：0.5mol／l；反应pH：9.5；C_TiO2：100g/l。更多还原

【Abstract】 Nano-TiO2 whose crystal size is from 8nm to 30nm is prepared by using homogeneous precipitation method using TiOSO4 as precursor and CO(NH2)2 as precipitator. The factors including of reaction temperature and time, TiOSO4/CO(NH2)2, [TiO2+], calcination temperature and time which have effect on production rate, crystal size and crystalline phase of nano-TiO2 are studied by XRD, TEM and DTA-TG Experimental results show that production rates of nano-TiO2 are increased with accretion of reaction temperature, TiOSO4/CO(NH2)2, reaction time and reduced with decreasing of [TiO2+]; Crystal size is largen with reaction temperature, [TiO2+], calcinations temperature and time. Crystalline phase of nano-TiO2 is transformed from amorphism to anatase, subsequently to rutile with accretion of calcinations temperature. Optimum reaction conditions are choiced by orthogonal experiments, which are that eaction temperature was 90 C, [TiO2+] is 0.8mol/l, reactiontime was 4h, TiOSO4/CO(NH2)2 was 1:3. Crystal shape changing is studied by DTA. Results which is in consistent with XRD show that crystalline phase of nano-TiO2 which is prepared in optimum reaction condition is transformed from amorphism to anatase in 470 C, from anatase to rutile in 830 C.It is researched on SiO2-coated for TiO2 and nano-TiO2 that has been prepared in optimum reaction conditions. Characters of SiO2-coated nano-TiO2, including of crystal size, shape, mechanism,chemical bond combining and surface composing, are studied by TEM, XPS, XRF. Optimum reaction conditions are gained. For TiO2, they are that reaction temperature was 85 C, reaction time was 5h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2 was 200g/l; For nano-TiO2, reaction temperature was 90 C, reaction time was 1h, concentration of Na2SiO4 was 0.5mol/l, pH was 9.5, concentration of TiO2was 100g/l.更多还原