Study On Synthesis Technology Of Inorganic Composite Membrane By In Situ Hydrothermenal Method

An idea on the preparation of inorganic membrane have been proposed that is combining the technology of conventional in situ hydrothermal method, because of the research status of inorganic membrane is high cost, complex process, long period of process and hard to apply to industry. We have designed the process technology that is wide distribution materials, low-cost, short period of process and simple process, have researched the main factors impacting membrane synthesis, and got the optimal preparation method.In this research of synthesis inorganic composite membrane, glass was used as support. The hydro gel was prepared by adding colloidal silica to an aqueous solution containing sodium aluminates, nickelous oxide and sodium hydroxide, dip by dip and stirred at 323 K for 3-4 h. The hydro gel was transferred to a PTFE vessel of 25 mL, in which the glass plate was immersed; then the vessel was sealed. The preparation was performed by setting the PTFE vessel in the muffle at 453K for a given period of time. XRD, SEM and AFM were used to characterize the membrane. In the static hydrothermal synthesis, supports placed horizontal had a largest area which contacted with the precipitated particles, on one hand the surface of horizontal supports was rougher of the membrane than the supports placed vertically. On the other hand, the horizontal placed supports formed more thick composite membrane. Due to faster formation of the membrane of horizontal supports, surface of the membrane would be easy to exit defects, and quality of membrane not as good as vertical supports under same condition. The surface of the membranes was prepared with the vertical support form rough become to smooth and to rough again with the increasing of synthesis time. The membrane prepared by in situ hydrothermal treatment 48 h could get a smooth surface. The composite membranes contained Si, O, and seldom Na, Al, Ni, and the thickness of it was about 820 nm. XRD examination of the material showed that the material was amorphous. The composite membrane could improve the luminousness of the support. During the preparation using PVA-2000 as template, polymers chain restrictions effect of template could cause the deeper depression. So the membrane without template was more even. Burning of organic compounds, in which membrane and the supports had a different thermal expansion coefficient, also could cause the disbalance of stress, led to cracks in the membrane. In this study also discussed the mechanism of the composite membrane composite film of the film, during the deposition process, parts of atomic which migrate to the lowest could formed membrane by layers growth, the other parts of the atomic was island formation. So the membrane grew by the combination of single-layer formation mode and island formation mode.