Studies On Preparation Of TiO₂/SiO₂ Nanocompsites By Adsorption Phase Reactor Technology

In-situ preparation of TiO2 nanoparticles on nano SiO2 in water-ethanol binary mixtures was studied in this dissertation. First, the research and application of nanocompsites and nano TiO2 were reviewed and the author introduced the preparation methods of nanocomposites in response to the dissertation. The author generalized the principles, characteristics and applications of traditional methods. And several kinds of preparation methods of nanocompsites via nanophase reactor (Reverse Microemulsion, Multipores Material and Layer Silicate) were represented detailed. Their principles, characteristics and applications were introduced, the advantage and disadvantage of this method were also generalized contrasted with traditional methods.A new preparation method of nanocompsites via nanophase reactor, called adsorption phase reactor technology, was presented. The principle and characteristic of this technology was represented combined with literatures. The literatures were generalized and the researches at present were illustrated with examples. Then the aspect which was not discussed deeply or not involved was also summarized. And on base of it the investigated orientation of this dissertation was presented.The author designed a series of experiment against the new system by the research on the literatures. Solvent replacement experiment provided direct evidence that there was water-rich adsorption layer and the reaction took place in the layer. The changes of the water in adsorption system were determined by KF-1 water microdetector and from these data the volume of the adsorption layer on SiO2 was calculated. By the blank experiment, the change of SiO2 after the experiment was found. TEM, XRD and electronic energy spectrum indicated uniform TiO2 particles laid over surface of SiO2. For discussing mechanics of the process in adsorption phase reactor technology, the author designed temperature, concentration and reaction time experiments. Then the adsorption and reaction mechanics were gained with kinds of analytical methods. Themechanics of adsorption had four characteristics: (1)The distribution of adsorption layer was very abroad; (2)The adsorption layer and the change of adsorption layer were non-uniform; (3)The influence of temperature on adsorption layer was very sensitive; (4)The change of adsorption layer could affect final pattern of TiO₂ nanoparticles. The hydrolysis reaction of tetrabutyl titanate in adsorption was special because the reactor was nanophase, the mechanics of hydrolysis reaction had three characteristics: (1)The hydrolysis reaction rate of tetrabutyl titanate was small; (2) The hydrolysis reaction in adsorption layer had three process, the influence of temperature on the last two process was small and different; (3) The diffusion rate was the most insensitive to temperature.At last, the work in dissertation was generalized and the problems which were unsolved in paper were represented base of this. The orientation of research in future was pointed out.