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Titolo:
Macroscopic heterogeneities in electroosmotic and pressure-driven flow through fixed beds at low column-to-particle diameter ratio
Autore:
Tallarek, U; Scheenen, TWJ; Van As, H;
Indirizzi:
Univ Wageningen & Res Ctr, Dept Biomol Sci, Wageningen NMR Ctr, NL-6703 HAWageningen, Netherlands Univ Wageningen & Res Ctr Wageningen Netherlands NL-6703 HA Netherlands Univ Wageningen & Res Ctr, Phys Mol Lab, NL-6703 HA Wageningen, Netherlands Univ Wageningen & Res Ctr Wageningen Netherlands NL-6703 HA Netherlands
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 36, volume: 105, anno: 2001,
pagine: 8591 - 8599
SICI:
1520-6106(20010913)105:36<8591:MHIEAP>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; FIELD-GRADIENT NMR; POROUS-MEDIA; CAPILLARY ELECTROCHROMATOGRAPHY; CHROMATOGRAPHIC COLUMNS; PACKED-BEDS; HYDRODYNAMIC DISPERSION; AXIAL-DISPERSION; LIQUID-CHROMATOGRAPHY; TAYLOR DISPERSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
93
Recensione:
Indirizzi per estratti:
Indirizzo: Tallarek, U Univ Magdeburg, Lehrstuhl Chem Verfahrenstech, Univ Pl 2, D-39106 Magdeburg, Germany Univ Magdeburg Univ Pl 2 Magdeburg Germany D-39106 g, Germany
Citazione:
U. Tallarek et al., "Macroscopic heterogeneities in electroosmotic and pressure-driven flow through fixed beds at low column-to-particle diameter ratio", J PHYS CH B, 105(36), 2001, pp. 8591-8599

Abstract

By using dynamic NMR microscopy with 40 mum 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. Itis shown that these wall effects are very systematic along the column axisfor both types of fluid flow. They can cause a persistent (i.e., tong-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 bedas we show by complementary pulsed field gradient NMR measurements.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/06/20 alle ore 01:46:56