Preparation of $α-Al2O3$ Supports for Thin Membrane Fabrication

Abstract

In this study, macroporous -alumina supports were prepared by using vacuumassisted filtration of α-Al2O3 suspensions with different particle size. The average particlesizes of the powders are 400 and 200 nm. The prepared supports had smooth and uniformsurface microstructure and well suited for the fabrication of thin continuous membrane.The microstructure consists of a random close-packing of 200 nm particles led to improvedsurface uniformity and roughness. ZnO spheres were prepared by homogeneousprecipitation and added to the colloidal suspension to modify the support structure andincrease the support flux. Structural parameters such as pore diameter and tortuosity ofthe prepared macroporous supports were estimated by using He, N2, CO2 permeancemeasurements. Slight pressure dependence in the permeance values indicated thecontribution of viscous flow to the Knudsen flow. The supports prepared by alumina powderwith a larger particle size exhibited a He permeance of three times higher than that ofprepared with a smaller particle size. The addition of ZnO resulted in the increase in Hepermeance value significantly for the support prepared by 400 nm particles in size. Hepermeance was in a range of 8.5-8.7x10-6 mol/(m2sPa) which is very close to the desiredvalue of 1x10-5 mol/(m2sPa).