| The nanometer titania is an important high performance fine inorganic materials. Because of its advantages, such as big specific surface area, high surface activity, good resistance to weathering, chemical resistance and good uvioresistant properties, nanosized TiO2 is applied in pianting materials, cosmetic, photosensitive materials, photocatalyst, project of environment, peeking material of the food and medicine field and so on. All kinds of these applications are connected with the crystal structure and shape of nanopowder, so the preparation of nanometer titania has become a research hot spot of nano-material science.Rutile TiO2 has many advantages, such as high refractive index, good heat resistance and stable chemical properties. But nowadays, few people research on the preparation of rutile TiO2 powders. Most of the methods to prepare rutile TiO2 need high-temperature calcination, but in this way it will cause agglomeration of the powders. This will limit the powder application. Based on the above reasons, we studied the preparation of rutile TiO2 powders. We selected TiO2 as precursor and got the products by boiling reflux and aging method. These two methods have such outstanding characteristics as simple equipment, fast rate of reaction and low reaction temperature etc. And all of these characteristics may offer the theoretical and practical basis for industrial production.The main research aspects are as follows:(1)The preparation of rutile titania by aging methodThe nanometer titania powders were prepared by aging at low temperature. The influences of reactant initial concentration, reaction temperatrue, reaction pH value etc were studied. The optimum condition of rutile titania were determined. The results as follows: higher initial concentration of reactant, lower reaction temperature, lower pH value and adding rutile seeds would have benefit to preparation of rutile TiO2 powders. The products we got under this condition of static state were needle-shaped, but when stirring, the shape became sphere.We synthesized the rutile TiO2 whisker by the simple aging method in the liquid phase, and found the appropriate reaction condition: [Ti4+]=2.0mol/L , temperature was70 C. Electron diffraction was used to characterize the whiskers. (2)The preparation of rutile titania by boiling reflux method.The nanometer titania powders were prepared by forced hydrolysis under boiling reflux method. In the experiment, the influences of reactant initial concentration, temperature rising rate were studied. Finally, we got the rutile TiO2 sphere of the particle size of 10nm with [Ti4+]=0.9mol/L and certain temperature rising rate.(3)The preparation of sphere-shaped titania by adding PO43-We controlled the size of titania by adding different concentration of H3PO4, NaH2PO4 and HEDP. The influences of reactant initial concentration, additive concentration on the particle size were researched. When the concentration of Ti4+ was about 1.0mol/L and [Ti4+].- [PO43-]=1: 0.02, we got the uniform sphere-shaped and mixed crystal titania.Studying the influences of adding PO43- by phosphomolybdate blue spetrophotometric method.We calcined the powders to get rutile TiO2, and found that the addition of PO43- had the stable effects of anatase TiO2. At certain additive concentration, some rutile TiO2 even transformed to anatase TiO2... |
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