Characterization And Mechanism Of The Surface Of Titanium Dioxide Coated

Titania, as an important white pigment with excellent covering power and whiteness, is widely used in paints, plastics, paper, rubber, fiber, graphite and cosmetics. Untreated titanium dioxide particles is very small, with high specific surface energy, and are very unstable. Larger particles were formed soon, that is metastable. For a certain amount of TiO2, the smaller the particles are, the stronger the gravitational attraction among particles are the easier the particles aggregate. TiO2 must be surfacely treated for practical application, i.e. form a continuous coating of film on the surface of TiO2 particles. Many aterials were used for coated titanium dioxide, but so far the most widely used inorganic coated at home and abroad is silicon, aluminum, zirconium compounds and other substances, that in a certain concentration of TiO2 slurry by adding acidic or alkaline pack film, then alkali or acid to make film coating in a certain pH conditions to form hydrated oxide particles deposited on the surface of TiO2.Al2(SO4)3.18H2O and Na2SiO3-9H2O were used for inorganic coated agent; HO(CH2CH2O)nH, C6H15O3N and Na(ClgH35O2) were used for organic coated agent. By means of liquid phase deposition method, the experiment for inorganic coatings on TiO2 particles were made under different conditions, composite particles with a surface layer coated on untreated TiO2.Then the surface of TiO2 was modified the effects on coating results were studied under different technological conditions.The technological parameters were decided according to the change of acid solubility, dispersion of TiO2 particles after coating.In addition,The thermodynamic analysis of coated Titania was studied in this paper. Ion concentration was woked out in different pH value and different temperature. Theoretical value of ion concentration was got and compared with theoretical value.Experimental results show that:by mesns of studing the relation between the height of dear water layer in settling experiment, grain size distribution and dispersing agent,pH value,temperature and dispersing agent were key factors. Dispersity of titania were influenced on them. It was founded that:recombination coatings was the best way in the surface modification of titanium dioxide.the optimal coming method of recombination coatings was 3% silica and 5% alumina; suspension pH=10 coming; reaction temperature was 80℃.Furthermore the thermodynamics TiO2 inorganic coating is analyzed and calculated, Ion concentration were calculated in different pH value,different temperature .and ion got,Theoretical comparison were compared with the experimental value.