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Thesis Advisor李晋林
Degree Grantor中国科学院研究生院
Abstract纳米金红石型TiO_2由于纳米材料其特殊的表面效应和粒度效应,使得其在催化剂载体,抗紫外线吸收剂,功能陶瓷等有着广泛的应用前景。本研究针对以入纳米金红石TiO_2制备方法中的不足,提出了一种新的制备方法-沉淀包覆溶出法:利用ZnCO_3包覆Ti(OH)_4 沉淀,使Ti(OH)_4沉淀的过滤、洗涤性能大大提高;酸溶后剩余的少量的ZnO与 H_2SO_4生成的ZnTiO_3 具有与金红石型TiO_2相似的晶体结构,能促进TiO_2从锐钛型向金红石型转化,从而降低了晶型转化温度,缩短了转化时间,抑制了粒了的长大。实验发现,当ZnO/TiO_2 (摩尔比)值为5/1时,控制反应温度约20~30 ℃,沉淀完20~30 ℃ Zn~(2+)后溶液 pH值为 7.0~7.3 ,所制得的沉淀包覆体易过滤、洗涤,干燥后粉体疏松,易碎。在500 ℃预焙解沉淀包覆粉体2h,可使ZnSO_4完全分解为 ZnO,Ti(OH)_4脱水为H_2TiO_3,而不生成ZnTiO_3。进一步利用浓度≤3mol/L时酸溶解97%的ZnO,溶解较快。在800 ℃时对H_2TiO_3焙烧1.5h,结果表明 H_2TiO_3已完全转变为金红石型TiO_2,其中TiO_2含量可达97%。其微观型貌为球型或椭球粒子,粒径约20~60nm。该粉体对240~400nm 的紫外线有较强的吸收,对 400~850nm 波段的光反射率达94%以上。
Other AbstractNanometer rutile TiO_2 has a widely applied prospect in catalyst carrier, absorbent of ultra violet, functional ceramics because of its particular surface effect and particle size effect. In the present work, a new method has been designed-the dissolving coated precipitate method to prepare nanometer rutile TiO_2: making ZnCO_3 particles coat on the Ti(OH)_4 particles so as to improve the properties of filtering and washing. Dissolving most of ZnO with dilute H_2SO_4, surplus ZnO will react with H_2TiO_3 to form ZnTiO_3, which has the same crystal structure as that of rutile TiO_2, and can accelerate the progress of transforming anatase TiO_2 to rutile TiO_2, reduce the temperature of crystal transformation and the transforming time, prohibit the particles from growing further. During the experiment, when ZnO/TiO_2 (mole ratio) is above 5/1, the pH value is 7.0~7.3 after precipitating ZnSO_4, and the reaction temperature is controlled at 20~30 ℃, the results show that the coated precipitate are loose and brittle. ZnCO_3 can be transformed to ZnO and Ti(OH)_4 can be transformed to H_2TiO_3 completely by calcining the coated precipitate at 500 ℃ for 2h and there was no ZnTiO_3 to be found. Using dilute H_2SO_4 to dissolve the outer 97% ZnO powder, ZnO will be dissolved quickly when H_2SO_4 concentration is ≤3mol/L. The resultsd of XRD proved that H_2TiO_3 containing 3%ZnO can be transformed rutile TiO_2 after having calcined H_2TiO_3 powder at 800 ℃ for 1.5h, TiO_2 content is about 97wt% in the product, the rutile TiO_2 particle is spherical or elliptic and the grain size is about 20~60nm. Using the ultraviolet spectrometer analysis to detect the optical properties of product, the powder had an intensive absorption of 240~400nm ultra violet lights, the absorptivity is over 90%, the refractive index is about 94% in the range of 400~850 nm wavelength light.
Document Type学位论文
Recommended Citation
GB/T 7714
林元华. 沉淀包覆溶出法制备纳米的金红石钛白粉及其性能表征研究[D]. 中国科学院研究生院,1998.
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