Electrophoretic NMR studies of electrical transport in fluid-filled porous systems

Holz, Manfred; Heil, Stefan R.; Schwab, Ilona A.

doi:10.1016/s0730-725x(01)00267-3

Cited by 13 publications

(14 citation statements)

References 7 publications

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“…In addition, the local S/V p ratio in the sectors with Sephadex gel matches the values of S/V p = 330,550 m -1 measured in previous work [8,14,16].…”

Section: Resultssupporting

confidence: 88%

“…Therefore, the measured tortuosities between 1.25 and 1.4 in these sectors are in good agreement with the calculated values. For Sephadex gel a tortuosity of s = 1.82 is reported [14,16]. Within the experimental error this value coincides with the measured local tortuosity of the Sephadex domain, which is between 1.8 and 2.0.…”

Section: Resultssupporting

confidence: 67%

“…With increasing fraction of Sephadex gel the local porosity increases up to values between 0.90 and 0.97 for pure Sephadex gel (see sectors 25-28). Holz and Heil [14,16] report for Sephadex gel a porosity of f = 0.88, thus the local porosities are slightly overestimated. Nevertheless, the local porosities obtained are in excellent agreement with the expected values.…”

Section: Resultsmentioning

confidence: 99%

“…The characteristics of each material are well known since they were tested by prior self-diffusion experiments on each component [14,15].…”

Section: Methodsmentioning

confidence: 99%

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Combination of Time‐Dependent Self‐Diffusion Measurements (Dynamic Imaging) with Magnetic Resonance Imaging

2006

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“…In addition, the local S/V p ratio in the sectors with Sephadex gel matches the values of S/V p = 330,550 m -1 measured in previous work [8,14,16].…”

Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

“…The characteristics of each material are well known since they were tested by prior self-diffusion experiments on each component [14,15].…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Combination of Time‐Dependent Self‐Diffusion Measurements (Dynamic Imaging) with Magnetic Resonance Imaging

2006

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“…Thus, it is not surprising that this field of ENMR application developed comparatively fast in the last years. The first successful measurements of ionic mobilities in porous systems, namely in gels, have been performed in the author's laboratory [26,27]. It could be demonstrated that in the fluidfilled pore space both the observed ionic self-diffusion coefficient D ± and the ionic mobility u ± in an external electric field show a dependence on the observation time ∆ (see Fig.…”

Section: Diffusion and Field-assisted Diffusion Of Ions In Porous Mediamentioning

confidence: 99%

Field-Assisted Diffusion Studied by Electrophoretic NMR

Holz

Diffusion in Condensed Matter

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Characterization of Structure and Transport in Porous Media by Pulsed Field Gradient (PFG) NMR Technique. Part I: Master Curve and Characteristic Inner Length

2006

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Systematic experimental studies focusing on the practical application of observation time dependent pulsed-field-gradient (PFG) NMR were performed. The objective was to provide engineering scientists with a reliable experimental tool for characterizing the structure and transport in fluid-filled porous media. Observation time dependent self-diffusion in glass bead packs as model systems was investigated, where the diffusing species (molecules of the solvent or dissolved particles) served as probes for the confining geometry in the porous medium. First, the basic question whether the obtainable structure information is independent of the actual mobility of the diffusing probe particles was examined experimentally. It could be demonstrated that plotting the normalized time-dependent diffusion coefficient D(t)/D 0 versus the actual migration length l D (t) during a given observation time t indeed yields a characteristic "master curve" that is independent of the mobility of the diffusing species, thus reflecting, as desired for a reliable method, solely the effects of the confining geometry of the porous system of interest. It was further shown that from the master curve a new quantity, i.e., a "characteristic inner length" or "correlation length" n D can be derived that corresponds to a path length in the porous medium, after which particles in the pore fluid experience an averaged restricting geometry and diffuse with an effective diffusion coefficient D eff . It turned out that n D is surprisingly short, that is, in the order of the bead radius. Moreover, it was demonstrated that normalization of this migration length with the bead radius yields a common master curve for all monodisperse bead packs used and thus, it is obviously possible to derive and record master curves for different kinds of packs, beds or other porous media as references that can be used to characterize or certify the kind of the porous matrix of interest.

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Electrophoretic NMR studies of electrical transport in fluid-filled porous systems

Cited by 13 publications

References 7 publications

Combination of Time‐Dependent Self‐Diffusion Measurements (Dynamic Imaging) with Magnetic Resonance Imaging

Combination of Time‐Dependent Self‐Diffusion Measurements (Dynamic Imaging) with Magnetic Resonance Imaging

Field-Assisted Diffusion Studied by Electrophoretic NMR

Characterization of Structure and Transport in Porous Media by Pulsed Field Gradient (PFG) NMR Technique. Part I: Master Curve and Characteristic Inner Length

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