Preparation of Ultrafine Powders by Reaction-Precipitation in Impinging Streams III Nano Titania

PREPARATION OF ULTRAFINE POWDERS BY REACTION-PRECIPITATION IN IMPINGING STREAMS III NANO TITANIA 

Nano Titania is one of the earliest nano materials to be applied commercially. It has a number of superior properties, such as super strong scattering and anti-ultraviolet capabilities, special electromagnetism and catalysis characteristics, especially the photocatalysis ability decomposing microbes, and also extremely high surface activity 

As for other inorganic nano materials, a number of preparation methods have been proposed for nano Titania. Because of its economic advantages and its simplicity, Li 

Actually, during the reactions, the meta-titanic acid H2Ti03 is precipitated first, which adsorbs considerably large amounts of water and soluble impurities such as ammonium sulfate, ammonium chloride etc, and also contains some insoluble impurity particles such as oxides of iron, strontium, and calcium etc. Therefore, it is essential to fully wash the precipitate to obtain a product of high purity. The insoluble and part of the soluble impurities can be removed by multiple washings ammonium chloride and ammonium sulfate are decomposed and released as the precipitate is later heated to 300°C and 700°C, respectively, during the calcination. 

During calcination the particles grow by themselves, but the growth rate is smoothed after achieving certain sizes and the crystalline form may also be partially changed. For example, some of the titanic crystalline may also appear in the product calcined at 600 °C for a long time. 

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