Correlation of structural and permeation properties in sol–gel-made nanoporous membranes

• Published in: Journal of colloid and interface science 2003-03, Vol.259 (2), p.322-330
• Main Authors: Kikkinides, E.S., Stoitsas, K.A., Zaspalis, V.T.
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Knudsen diffusion; Membranes; Nanoporous membranes; Simulation of pore structure; Sol–gel techniques; Viscous flow
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/S0021-9797(02)00210-2

The aim of the present work was to establish a fundamental link between the basic structural properties of ceramic nanoporous membranes made by the sol–gel process and their respective transport properties, for a systematic evaluation of their performance in gas and liquid applications. For this purpose, supported and unsupported γ-Al 2O 3 and TiO 2 membranes were prepared from different colloidal dispersions (sols) by a sol–gel dipping process followed by drying and calcination, resulting in structures of crystallites of different shape and stacking arrangement. Accordingly, the pore structure of each membrane was simulated employing process-based reconstruction techniques and the permeation properties were predicted by solving the appropriate transport equations in the generated structures. Excellent agreement was achieved between the computed and experimental permeability values in the Knudsen and viscous flow regimes, validating the considerations made regarding the basic structural characteristics and the procedure for generation of the membrane structures. Moreover, it was shown that the shape and stacking arrangement of the primary particles (crystallites) of the sol have a major impact on the formation of pathways in the membrane pore structures and control the transport and therefore also the separation properties of these materials.