Abstract

MALDONADO, Rainier; GARCIA, Mariana; PAEZ, Victoria  and  TORREALBA, Karla. Transfer mechanism of water, methanol and ethanol by pervaporation as pure substances in zeolites DD3R. Rev. Fac. Ing. UCV [online]. 2014, vol.29, n.1, pp.75-86. ISSN 0798-4065.

The study of diffusion through nanoporous ceramic membranes is relevant for the improvement of separation techniques in industry. The zeolite Decadodecasil 3R (DD3R) is a pure silica material with a pore window size that allows molecular size exclusion, selective for water permeation and for its separation from other substances of larger molecular size. In this work experimental data for the diffusion of pure substances (water, methanol and ethanol) by pervaporation through a zeolite DD3R membrane, supported on alumina, were modeled in order to identify the mechanism governing the mass transfer in the membrane. For the three substances under study, different mechanisms of mass transport in porous media were analyzed at different conditions of temperature and pressure. It was found that the pervaporation of water in the DD3R zeolite membrane corresponds to a surface diffusion mechanism, in a parallel combination with capillary condensation diffusion. Methanol molecular transport is due to surface diffusion with a contribution of Knudsen diffusion through crystalline defects in the zeolite structure. Ethanol permeation can be described exclusively by surface diffusion.

Keywords : DD3R Zeolite; Knudsen diffusion; Maxwell-Stefan model equations; Pervaporation.

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