Kumar, Abhijeet ; Kleinen, J. ; Venzmer, Joachim ; Gambaryan-Roisman, Tatiana (2017)
Effect of Geometry on Electrokinetic Characterization of Solid Surfaces.
In: Langmuir, 33 (30)
doi: 10.1021/acs.langmuir.7b00344
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
An analytical approach is presented to describe pressure-driven streaming current (Istr) and streaming potential (Ustr) generation in geometrically complex samples, for which the classical Helmholtz−Smoluchowski (H−S) equation is known to be inaccurate. The new approach is valid under the same prerequisite conditions that are used for the development of the H−S equation, that is, the electrical double layers (EDLs) are sufficiently thin and surface conductivity and electroviscous effects are negligible. The analytical methodology is developed using linear velocity pro files to describe liquid flow inside of EDLs and using simplifying approximations to describe macroscopic flow. At first, a general expression is obtained to describe the Istr generated in different cross sections of an arbitrarily shaped sample. Thereafter, assuming that the generated Ustr varies only along the pressure-gradient direction, an expression describing the variation of generated Ustr along the sample length is obtained. These expressions describing Istr and Ustr generation constitute the theoretical foundation of this work, which is first applied to a set of three nonuniform cross-sectional capillaries and thereafter to a square array of cylindrical fibers (model porous media) for both parallel and transverse fiber orientation cases. Although analytical solutions cannot be obtained for real porous substrates because of their random structure, the new theory provides useful insights into the effect of important factors such as fiber orientation, sample porosity, and sample dimensions. The solutions obtained for the model porous media are used to device strategies for more accurate zeta potential determination of porous fiber plugs. The new approach could be thus useful in resolving the long-standing problem of sample geometry dependence of zeta potential measurements.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2017 |
| Autor(en): | Kumar, Abhijeet ; Kleinen, J. ; Venzmer, Joachim ; Gambaryan-Roisman, Tatiana |
| Art des Eintrags: | Bibliographie |
| Titel: | Effect of Geometry on Electrokinetic Characterization of Solid Surfaces. |
| Sprache: | Englisch |
| Publikationsjahr: | 2017 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Langmuir |
| Jahrgang/Volume einer Zeitschrift: | 33 |
| (Heft-)Nummer: | 30 |
| DOI: | 10.1021/acs.langmuir.7b00344 |
| URL / URN: | http://dx.doi.org/10.1021/acs.langmuir.7b00344 |
| Kurzbeschreibung (Abstract): | An analytical approach is presented to describe pressure-driven streaming current (Istr) and streaming potential (Ustr) generation in geometrically complex samples, for which the classical Helmholtz−Smoluchowski (H−S) equation is known to be inaccurate. The new approach is valid under the same prerequisite conditions that are used for the development of the H−S equation, that is, the electrical double layers (EDLs) are sufficiently thin and surface conductivity and electroviscous effects are negligible. The analytical methodology is developed using linear velocity pro files to describe liquid flow inside of EDLs and using simplifying approximations to describe macroscopic flow. At first, a general expression is obtained to describe the Istr generated in different cross sections of an arbitrarily shaped sample. Thereafter, assuming that the generated Ustr varies only along the pressure-gradient direction, an expression describing the variation of generated Ustr along the sample length is obtained. These expressions describing Istr and Ustr generation constitute the theoretical foundation of this work, which is first applied to a set of three nonuniform cross-sectional capillaries and thereafter to a square array of cylindrical fibers (model porous media) for both parallel and transverse fiber orientation cases. Although analytical solutions cannot be obtained for real porous substrates because of their random structure, the new theory provides useful insights into the effect of important factors such as fiber orientation, sample porosity, and sample dimensions. The solutions obtained for the model porous media are used to device strategies for more accurate zeta potential determination of porous fiber plugs. The new approach could be thus useful in resolving the long-standing problem of sample geometry dependence of zeta potential measurements. |
| Fachbereich(e)/-gebiet(e): | 16 Fachbereich Maschinenbau 16 Fachbereich Maschinenbau > Fachgebiet für Technische Thermodynamik (TTD) Profilbereiche Profilbereiche > Thermo-Fluids & Interfaces |
| Hinterlegungsdatum: | 28 Aug 2017 16:12 |
| Letzte Änderung: | 07 Aug 2019 14:45 |
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