PREPARATION OF A SOL-GEL DERIVED THIN MEMBRANE ON A POROUS CERAMIC HOLLOW FIBER BY THE FILTRATION TECHNIQUE

A filtration technique is proposed to prepare a sol-gel derived thin membrane, instead of a dip technique based on capillary action. A pinhole-free gamma-alumina membrane is formed from a boehmite sol on the inner surface of a porous ceramic hollow fiber support (2.0 mm o.d., 1.4 mm i.d.), which is not thick enough to apply the dip technique. Pre-treatments to wet the support are essential to avoid pinholes. The membrane formation rate is proportional to the square root of the filtration time, suggesting the filtration resistance is mainly located in the formed gel layer. Gas permeation and ultrafiltration measurements indicate that the present method is effective in preparing a homogeneous sol-gel membrane.