Characterization of Pore Geometry of Alumina Membrane

Pore radius and tortuosity of an alumina membrane were calculated from the flux through the membrane and liquid capillary rise rates of several solvents, and compared with the values obtained by convensional methods. Tortuosity value by this method agreed well with that obtained by the measurement of effective ionic conductivity of the alumina membrane. However, pore radius by this method was 1.17 times larger than that by the Hg intrusion method. This difference was explained by the pore geometry that is, pores in the alumina membrane are rectangle because the membrane was prepared by packing alunina particles. By the Hg intrusion method, measured pore radius corresponds to that of inscribed circles for rectangle alumina pores. On the other hand, measured value by the transport phenomena of liquids through membrane voids is equivalent to the radius of a circle of which area is comparable to the cross sectional area of a rectangle alumina pore. Therefore, geometrical coefficient which accounts for the discrepancy of pore shape from circle was derived by comparing the pore radius values by this method with those by Hg intrusion method.