Design And Characterization Of Rutile Nano Titania Composites And Studies On Preparation Of Rice Husk Based High-Purity Nano Silica

Titania has been widely used as the principal white pigment material in various branches of industry, because of its high refractive index, high dielectric constant, and chemical stability, even in strongly acidic or basic environments.With the development of manufacturing technology, it is possible for people to prepare nanosize titania which has much better properties than bulk titania because of the greatly decrease in size. In this thesis, the main topic is the design and characterization of functional nanosize titania materials with deferent crystalline phases and morphology.TiO2/Wollastonite composite was first obtained by chemical organization of titania and wollastonite.All kinds of detections reveal that the properties of TiO2/Wollastonite composite are similar to that of titania.On the other hand, the phase transformations of all these materials were studied.On the basis of experiments some beneficial principles and conclusions were brought forward as follows.TiO2/Wollastonite composites were first achieved by organizing a thin film of titania particles on the surface of wollastonite powders.Three methods were used to fabricate the composites and better organization technologies have been well mastered.It is notable that rutile TiO2/wollastonite composites were directly obtained at lower temperature by adding SnO2 as the nuclei.The particle sizes of composites were about 0.2~0.4(m by SEM, which is in the range of optimum particle sizes of titania powders.But the grain size of titania particles on the surface of wollastonite powders were only 3(4 nm when observed by TEM.Also the composite presents similar whiteness compared to titania.In short, TiO2/wollastonite composites have both good properties of titania and nanomaterial.Another research work is recycling the silica from rice husk.It was shown that pure, nano amorphous silica can be obtained from rice husk by burning the RH at 873-1073 K after leaching RH in HCl, presented a homogeneous particle size distribution compared to the sample, preparation techniques.The product with narrow particle size distribution (30-50 nm) and the purity exceed 99.5%.