Study On Preparation Of Alumina Functional Materials And Mesoporous Silica From Bentonite

Bentonite is known as the "universal clay". This unique clay is widely used in chemical and pharmaceutical industries, because it can be processed into binders, suspending agents, thixotropic agents, catalysts, etc. In recent years, the development and utilization of bentonite has increased rapidly, particularly in the deep processing and efficient usage field. In this thesis, the synthesis processes of alumina microsphere, ultrafine alumina and mesoporous silica were studied by use of aluminum sulfate, aluminum ammonium sulfate and sodium silicate, which were prepared by bentonite as a raw material. Production equipment was suggested through the studies, as well as economic benefits and environment analysis. The product structure and morphology of alumina microsphere, ultrafine alumina and mesoporous silica were fully characterized by XRD, SEM, FT-IR and N2 adsorption-desorption.(1) The synthesis processes of alumina microsphere were studied through aluminum sulfate prepared by bentonite. The recovery ratio of alumina can reach up to 97%. It can be clearly seen by use of XRD and SEM that the sample was a-alumina powder with spherical and ultrafine, with an average size of about 4μm.(2) The optimum conditions for production of ultrafine alumina experiment was determined. XRD and SEM reveal the sample was a-alumina powder with clubbed or bacilliform, and its average size was 300-400 nm.(3) The synthesis processes of mesoporous silica were studied through sodium silicate prepared by bentonite. It can be clearly seen by the Small Angle XRD diagram that diffraction peaks are similar to that of mesoporous materials MCM-41.N2 adsorption-desorption isotherm, which was a typical IV isothermal adsorption curve, has a small hysteresis loop and confirms that these samples are indeed typical mesoporous materials.(4) Economic benefit estimation investigations show that alumina microsphere and mesoporous silica prepared from bentonite is cost effective. Further, environmental analysis shows that there is essentially zero waste pollution produced by the synthetic process, which demonstrates that it is also cleaner than previous methods.