Preparation Of Nanometer TiO₂ By Means Of Chemical Precipitation Method

Nanometer material is a new kind of materials developing gradually at the end of 80's and beginning of 90's in 20th century. Nanometer titanium dioxide(TiO2) is an important kind of new inorganic functional materials, applied to many aspects of industrial and daily life widely because of many excellent properties such as high photocatalytic activities, powerful capability to shield ultraviolet ray, queer color effect and so on. It's preparation and application is getting more and more attention in the world.Proceed from the present situation of nanometer TiO2 powder industry in our country, confront more problems in preparation of nanometer TiO2. On the base of analyzing advantages and disadvantages of existing every methods, Neutralization precipitation method is adopted, using self-prepare TiOSO4 solution as raw material, soda as precipitant to precipitate titanous hydroxide precipitation , then obtained anatase nanometer titanium dioxide after heat treatment. Due to preparing high grade rutile nanometer titanium dioxide in the same method have more disadvantages such as tall calcining heat, easy agglomerate, reunite gravely and difficult to attain the nanometer grade. Hence we combined coprecipitation method, using zinc carbonate as enclosure dose causing the crystal nucleus can not grow up, Zinc titanate acts as phase-transition accelerant, thereby we can obtain rutile nanometer TiO2 powder at lower calcining temperature and in briefer calcining time relatively. This method's installations are simple, operation is easily control, repeatability is powerful. Moreover resolve the difficult of filtration and scrubbing of titanous hydroxide and control effectively growing up and reunion.In this paper, concentrated sulfuric acid and titanium dioxide are used to prepare the TiOS04 solution that test later required under long time heat. The influences of reaction time and reaction temperature to yield of TiOSO4 are discussed.In the experiment of preparing TiO2 powder, reaction temperature, pH values, material ratio, operation way, velocity of feed, calcining heat and time are researched by the principle of nucleation and growth in thermodynamics and kinetics. The more favorable experiment conditions of preparing anatase nanometer TiO2 powder are obtained from a lot of data.Preparation technology of rutile nanometer TiO2 powder is researched on the base of experiment of anatase nanometer TiO2 powder. The influences of enclosure dose's quantity, preroasting temperatures phase-transition accelerant's quantity and calcining intensity and so on on the properties of inclusion body-ZnTiO3/Ti(OH)4, granule size and properties of rutile nanometer TiO2 powder are discussed. Phase composition of nanometer TiO2 is analyzed by X-ray diffraction, granule size and appearance of nanometer TiO2 are analyzed by scanning electron microscope and transmission electron microscope, so we modified the conditions of experiment and obtained even and dispersive nanometer grade rutile TiO2 powder that is spheric or oval-shaped. At the same time, phase-transition accelerant mechanism of zinc titanate in the product act to rutile nanometer TiO2 powder is discussed.The entire experiment result makes known, it is simple and practicable that prepare nanometer TiO2 powder by means of chemical precipitation method in laboratory. It is interesting to realize industrialize production of nanometer TiO2 powder.