Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 110741
Title Macroscopic heterogeneities in electroosmotic and pressure-driven flow through fixed beds at low column-to-particle diameter ratio
Author(s) Tallarek, U.; Scheenen, T.W.J.; As, H. van
Source The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 105 (2001). - ISSN 1520-6106 - p. 8591 - 8599.
Department(s) Biophysics
Publication type Refereed Article in a scientific journal
Publication year 2001
Abstract By using dynamic NMR microscopy with 40 μm spatial resolution we have demonstrated the existence of specific wall effects in electroosmotic and pressure-driven flows through a fixed bed at low column-to-particle diameter ratio. While the geometrical wall effect encountered in pressure-driven flow through the packed capillary is due to the radial distribution of interstitial porosity, with increasing void space closer to the wall, the electrokinetic wall effect is caused by different values of the zeta-potential associated with the inner surface of the capillary and those of the particles. It is shown that these wall effects are very systematic along the column axis for both types of fluid flow. They can cause a persistent (i.e., long-time) disequilibrium in the axial dispersion behavior, and associated correlation lengths of the flow field may cover the total radius of the packed capillary needing trans-column equilibration. The characteristic times of these macroscopic flow heterogeneities in electroosmotic and pressure-driven flows exceed by far those of the stagnant mobile phase mass transfer in the bed as we show by complementary pulsed field gradient NMR measurements.
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