Preparation And Coating Of The Micro Spherical TiO₂

Due to the high refractive index, hiding power, tinting strength and inert chemicalproperties, spherical micrometer titania powders are most widely used in painting,plastic, papermaking, ployster, printing ink to improve quality of the product effectivelyand enhance properties of product, which is the most important resource in thefabricating of dye chemical product.Nowadays, although our country has becomepowerful in the manufacturing and employing of TiO2powder in the world, generalusing TiO2in medium and low is the main product, while the making and coating ofhigh quality TiO2falls behind far away from America and Japanese, titanium powderused in high grade painting and printing ink relies on import, practically.TiO2powder in good dispersion and uniform particle size can be manufactured byhydrolysis of titanium alkoxides, but it cost a lot and poor in application prospect.According to existing document, cheap inorganic titanium salt can be used to prepareTiO2in good morphology. This article use Ti(SO4)2to make nanometer TiO2in narrowparticle size distribution bywater bath hydrolysis in normal pressure and microwaveassistant process and coat the titamium powder with silicon and aluminum inmultiplemethodsto overcome agglomeration decrease photocatalytic activity. With the assist ofultraphonic, the coating time and concentration of coating agent are dicussed and theeffect of coating is verifiedby photocatalytic testing and obtain the optical coatingparameters. According to the making and coating of nanometer TiO2, the mainconclusion is as follows:(1)Spherical anatase TiO2in small particle diameter can be made with Ti(SO4)2bywater bath in normal pressure and microwave assistant process, the particle size ofTiO2by microwave assistant is bigger than water bath in normal pressure. The opticalparameters of hydrolusis reaction are: concentration of Ti(SO4)2is0.02mol/L-1, PVPwas used as surfactant, the volume ratio of n-propyl alcohol to water of the solution iscontrolled to be1.(2)TiO2obtained with different composite coating is anatase type. XRD shows thatthe obtained particle has a sharp peak and narrow peak width which indicates the goodcrystalline. This treatment improves the dispersibility and photocatalytic activity of theTiO2particle.(3)Both of sigle component coating and Composite coating withSiO2/Al2O3can avoid photocatalytic activity well in ultraphonic assistant process, but the compositecoating is better, and the optical parameter of coating is: at70℃，the mass fraction ofSiO2/Al2O3is3%.(4)According to the study results, the composite coating mechanism of SiO2/Al2O3inultraphonic is that at proper pH, the adding coating agent react to hydrate precipitatedparticles, the hydrate adsorbed at the surface of TiO2particle and chemical bonded withthe·OH, with a series of chain reaction, a compact and uniform in fine densitycomposite film is formed.