Preparation of Al2O3 Supports for Thin Membrane Fabrication

Abstract

In this study, macroporous a-alumina supports were prepared by using vacuum assisted filtration of α-Al₂O₃suspensions with different particle size. The average particle sizes of the powders are 400 and 200 nm. The prepared supports had smooth and uniform surface 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 improved surface uniformity and roughness. ZnO spheres were prepared by homogeneous precipitation and added to the colloidal suspension to modify the support structure and increase the support flux. Structural parameters such as pore diameter and tortuosity of the prepared macroporous supports were estimated by using He, N₂, CO₂ permeance measurements. Slight pressure dependence in the permeance values indicated the contribution of viscous flow to the Knudsen flow. The supports prepared by alumina powder with a larger particle size exhibited He permeance of three times higher than that of prepared with a smaller particle size. The addition of ZnO resulted in the increase in He permeance value significantly for the support prepared by 400 nm particles in size. He permeance was in a range of 8.5-8.7x10^-6 mol/(m²sPa) which is very close to the desired value of 1x10^-5 mol/(m²sPa).

Keywords

• membrane,support,alumina,high flux,colloidal processing

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