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

Synthesis of ZnO/SiO₂ nanocomposite materials in a nanoreactor which formed by the water-rich adsorption layer on the surface of SiO₂ were studied in this dissertation.First, the characteristic and application of ZnO nanoparticles were reviewed. Also the traditional methods and microscale reaction technology of preparing nano-ZnO were introduced in details. And the author introduced the principle and characteristic of adsorption phase nanoreactor technology including its principle and its progress. Then the research orientation of this paper was proposed on the basic of summarizing the achievements obtained. It was to study the principle of preparing nano-ZnO by this technology in a much higher concentration of the reactants. And this may be a foundation for the further study of the adsorption phase nano-reactor technology.For the established system the author designed a series of experiments including water concentration, NaOH concentration and temperature experiments. The influence of these factors to the distribution of NaOH and the products ZnO were gained with the help of many kinds of analytical methods such as TEM, XRD, Complexometric titration and Acid and alkali titrate.(1) Under certain conxentration of NaOH, the grain size of ZnO change slowly in a little concentration of water. Then it increases as the increasing of the congcentration of water. Finally it keeps at a steady one. Because there are two kinds of water adsorption layer on the surface of silica. And the distribution of NaOH changes accordingly. But the reaction zone dose not change, the reaction is controlled in the adsorption layer.(2) Different from the study result of low concentration of NaOH, with the increasing of the concentration of NaOH, the distribution of NaOH in the two phases changed from the non-ideal inter-phase distribution to the ideal inter-phase distribution under certain concentration of system water and temperature. The grain size of ZnO changes slowly in the first stage and it becomes small in the second stage.(3) The reaction zones changes from only the adsorption layer to both the two zones the as the temperature rised to a certain one. The grain size of ZnO becamessmaller in the adsorption layer and then it obviously increases because of the change of reaction zones.Then the ZnO/SiO₂ prepared by the adsorption phase nanoreactor technology were used as the catalyst for AC foaming agent, and found that it played well.At last, the work in the dissertation was generalized, and the problems which still need to discuss in paper were represented.