Preparation of alumina hollow fiber ultrafiltration membrane by filtering coating

The filtering coating method was introduced to prepare gamma-Al2O3 ultrafiltration membrane using alpha-Al2O3 hollow fiber microfiltration membrane as substrate. The thermostabitity, phase transformation, structure and appearance of ultrafiltration membrane were characterized by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy, respectively. The results showed that the gamma-Al2O3 ultrafiltration membrane with support prepared by filtering coating method is defect-free. The membrane is of gas selectivity, and the separation factors of nitrogen to argon are 1.133 and 1.139 at 0.3 and 0.4 MPa respectively. It was showed that the gas diffusion through the membrane is governed by Knudsen diffusion mechanism. The most probable pore diameter of an unsupported membrane after calcination at 700 degreesC is about 4.5 nm and its specific surface area is 282.9 m(2)/g characterized by nitrogen isothermal adsorption measurement.