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Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids.

ABSTRACT: Under certain conditions, during binary mixture adsorption in nanoporous hosts, the concentration of one component may temporarily exceed its equilibrium value. This implies that, in contrast to Fick's Law, molecules must diffuse in the direction of increasing rather than decreasing concentration. Although this phenomenon of 'overshooting' has been observed previously, it is only recently, using microimaging techniques, that diffusive fluxes in the interior of nanoporous materials have become accessible to direct observation. Here we report the application of interference microscopy to monitor 'uphill' fluxes, covering the entire period of overshooting from initiation until final equilibration. It is shown that the evolution of the profiles can be adequately predicted from the single-component diffusivities together with the binary adsorption equilibrium data. The guest molecules studied (carbon dioxide, ethane and propene) and the host material (ZSM-58 or DDR) are of practical interest in relation to the development of kinetically selective adsorption separation processes.

SUBMITTER: Lauerer A

PROVIDER: S-EPMC4518250 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids.

Lauerer Alexander A Binder Tomas T Chmelik Christian C Miersemann Erich E Haase Jürgen J Ruthven Douglas M DM Kärger Jörg J

Nature communications 20150716

Under certain conditions, during binary mixture adsorption in nanoporous hosts, the concentration of one component may temporarily exceed its equilibrium value. This implies that, in contrast to Fick's Law, molecules must diffuse in the direction of increasing rather than decreasing concentration. Although this phenomenon of 'overshooting' has been observed previously, it is only recently, using microimaging techniques, that diffusive fluxes in the interior of nanoporous materials have become ac ...[more]

PMID: 26177626

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Dataset Information

Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids.

Publications

Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids.

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