The Electrodiffusion Theory of Electrophoresis

Dukhin, S. S.

doi:10.1007/978-1-4899-5666-8_36

Cited by 6 publications

(6 citation statements)

References 11 publications

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“…7 As originally explained by Dukhin and coworkers, 8,9 the high surface charge results in an exponential amplification of the counterion concentration near the surface, enabling significant ionic currents through the diffuse portion of the double layer. This "surface conduction" mechanism affects the dominant electrokinetic transport through counterion exchange between the diffuse-charge ("Debye") layer and the surrounding electro-neutral bulk.…”

Section: A Backgroundmentioning

confidence: 90%

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Nonlinear electrophoresis at arbitrary field strengths: small-Dukhin-number analysis

Schnitzer

Yariv

2014

Physics of Fluids

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Smoluchowski's formula for thin-double-layer electrophoresis does not apply for highly charged particles, where surface conduction modifies the electrokinetic transport in the electro-neutral bulk. To date, systematic studies of this nonzero Dukhinnumber effect have been limited to weak fields. Employing our recent macroscale model [O. Schnitzer and E. Yariv, "Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction," Phys. Rev. E 86, 021503 (2012)], valid for arbitrary Dukhin numbers, we analyze herein particle electrophoresis at small (but finite) Dukhin numbers; valid for arbitrary fields, this asymptotic limit essentially captures the practical range of parameters quantifying typical colloidal systems. Perturbing about the irrotational zero-Dukhin-number flow, we derive a linear scheme for calculating the small-Dukhin-number correction to Smoluchowski's velocity. This scheme essentially amounts to the solution of a linear diffusion-advection problem governing the salt distribution in the electro-neutral bulk. Using eigenfunction expansions, we obtain a semi-analytic solution for this problem. It is supplemented by asymptotic approximations in the respective limits of weak fields, small ions, and strong fields; in the latter singular limit, salt polarization is confined to a diffusive boundary layer. With the salt-transport problem solved, the velocity correction is readily obtained by evaluating three quadratures, corresponding to the contributions of (i) electro-and diffuso-osmotic slip due to polarization of both the Debye layer and the bulk; (ii) a net Maxwell force on the electrical double layer; and (iii) Coulomb body forces acting on the space charge in the "electro-neutral" bulk. The velocity correction calculated based upon the semi-analytic solution exhibits a transition from the familiar retardation at weak fields to velocity enhancement at moderate fields; this transition is analytically captured by the small-ion approximation. At stronger fields, the velocity correction approaches a closed-form asymptotic approximation which follows from an analytic solution of the diffusive boundary-layer problem. In this régime, the correction varies as the 3/2-power of the applied field. Our smallDukhin-number scheme, valid at arbitrary field strengths, naturally lends itself to a tractable analysis of nonlinear surface-conduction effects in numerous electrokinetic problems. C 2014 AIP Publishing LLC. [http://dx

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Section: A Backgroundmentioning

confidence: 90%

“…41 and 42. The weak-field theories of Dukhin 8 and O'Brien and Hunter 10 are valid for arbitrary Dukhin numbers but are limited to weak fields. The results derived in the present paper focus upon small but finite Dukhin numbers, thus removing the weak-field limitation.…”

Section: Strong Fields-diffusive Boundary Layermentioning

confidence: 99%

Nonlinear electrophoresis at arbitrary field strengths: small-Dukhin-number analysis

Schnitzer

Yariv

2014

Physics of Fluids

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“…It was later realized, however, that this model can strongly oversimplify the system in the close vicinity of the solid–liquid interface . Due to different factors such as surface roughness, gel-like surface properties, or specific behavior of water molecules in contact with a solid, a thin layer of immobilized water close to the surface can exist, forming the so-called “stagnant layer”.…”

Section: Introductionmentioning

confidence: 99%

Extension of a Classic Thin Double Layer Polarization Theory of Colloidal Suspensions to Include the Stagnant Layer Conductivity

Grosse

2011

J. Phys. Chem. B

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A rigorous extension of the classic Dukhin-Shilov thin double layer polarization theory including the stagnant layer conductivity is presented. Precisely the same assumptions and approximations made in the original theory are maintained, and the same adsorption isotherms are used as in most of the existing numerical calculations. The obtained analytical results improve upon existing approximate extensions, mainly for low surface conductivities and high surface potentials and for high surface conductivities and low surface potentials. Moreover, they avoid the assumption that all the adsorbed ions in the stagnant layer must have a single sign. Finally, they present a very good agreement with numerical calculations specifically made using the same system parameters.

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“…A major drawback in the application of CE to biocolloidal and liposomal analysis is that the interpretation of electrophoretic mobilities and the modeling of these structures is typically based on traditional colloidal theories such as those developed by Overbeek, , Booth, , O'Brien, − and Dukhin, − which do not take into account the unique properties of these populations. This has led to difficulties in the interpretation of data and limited the usefulness and applicability of the information obtained.…”

Section: Introductionmentioning

confidence: 99%

Effects of Deformability, Uneven Surface Charge Distributions, and Multipole Moments on Biocolloid Electrophoretic Migration

Pysher

Hayes

2005

Langmuir

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Liposomes have been widely used as cellular and bioparticle mimics due to their lipid bilayer structure and relative ease of production and manipulation. Such biocolloids are frequently characterized by capillary electrophoresis (CE), which promises a wealth of information about such properties as surface charge, composition, and rigidity. The applicability of this information is somewhat limited, however, since it is interpreted with colloidal theories that do not account for the unique properties of biocolloids. In this work, the effects of deformability, mobile surface charges, intrinsic polarizability, and uneven surface charge distributions are incorporated into colloidal theories in order to better model the electrophoretic behaviors of liposomes.

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The Electrodiffusion Theory of Electrophoresis

Cited by 6 publications

References 11 publications

Nonlinear electrophoresis at arbitrary field strengths: small-Dukhin-number analysis

Nonlinear electrophoresis at arbitrary field strengths: small-Dukhin-number analysis

Extension of a Classic Thin Double Layer Polarization Theory of Colloidal Suspensions to Include the Stagnant Layer Conductivity

Effects of Deformability, Uneven Surface Charge Distributions, and Multipole Moments on Biocolloid Electrophoretic Migration

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