Effects of electrostatic correlations on electrokinetic phenomena

Storey, Brian D.; Bazant, Martin Z.

doi:10.1103/physreve.86.056303

Cited by 152 publications

(212 citation statements)

References 56 publications

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“…Finally, our description of the electric double layer also relies on a mean-field description. Recently, Bazant, Storey, and co-workers have developed models for the electric double layer when the mean-field approximation breaks down [57,58]. Incorporating these additional effects constitutes a natural extension of this study.…”

Section: Discussionmentioning

confidence: 97%

Nonlinear electrophoresis in the presence of dielectric decrement

et al. 2016

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The nonlinear phenomena that occur in the electric double layer (EDL) that forms at charged surfaces strongly influence electrokinetic effects, including electro-osmosis and electrophoresis. In particular, saturation effects due to either dielectric decrement or ion crowding effects are of paramount importance. Dielectric decrement significantly influences the ionic concentration in the EDL at high ζ potential, leading to the formation of a condensed layer near the particle's surface. In this article, we present a model incorporating both steric effects due to the finite size of ions and dielectric decrement to describe the physics in the electric double layer. The model remains valid in both weakly and strongly nonlinear regimes, as long as the electric double layer remains in quasiequilibrium. We apply this model to the study of two archetypal problems in electrokinetics, namely the electrophoresis of particles with fixed surface charges and the electrophoresis of ideally polarizable particles.

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Section: Discussionmentioning

confidence: 97%

Nonlinear electrophoresis in the presence of dielectric decrement

et al. 2016

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“…It is therefore important to take gradients in into account in Gauss' law. Electrostatic correlations were recently included in a fourth-order modified Poisson equation [38] that could be applied to the case of polymer adsorption as well. However, we will limit our model to the second-order Poisson equation described by Eq.…”

Section: Electrostatic Potentialmentioning

confidence: 99%

Adsorption of charged and neutral polymer chains on silica surfaces: The role of electrostatics, volume exclusion, and hydrogen bonding

2015

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We develop an off-lattice (continuum) model to describe the adsorption of neutral polymer chains and polyelectrolytes to surfaces. Our continuum description allows taking excluded volume interactions between polymer chains and ions directly into account. To implement those interactions, we use a modified hard-sphere equation of state, adapted for mixtures of connected beads. Our model is applicable to neutral, charged, and ionizable surfaces and polymer chains alike and accounts for polarizability effects of the adsorbed layer and chemical interactions between polymer chains and the surface. We compare our model predictions to data of a classical system for polymer adsorption: neutral poly(N -vinylpyrrolidone) (PVP) on silica surfaces. The model shows that PVP adsorption on silica is driven by surface hydrogen bonding with an effective maximum binding energy of about 1.3 k B T per PVP segment at low pH. As the pH increases, the Si-OH groups become increasingly dissociated, leading to a lower capacity for H bonding and simultaneous counterion accumulation and volume exclusion close to the surface. Together these effects result in a characteristic adsorption isotherm, with the adsorbed amount dropping sharply at a critical pH. Using this model for adsorption data on silica surfaces cleaned by either a piranha solution or an O 2 plasma, we find that the former have a significantly higher density of silanol groups.

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“…Such correlations lead to a breakdown of the mean-field approximation, and a non-local theory [47,48] that can account for strong fluctuations in the electrostatic potential is required to improve upon the standard continuum theory [49].…”

Section: Discussionmentioning

confidence: 99%

The influence of excluded volume and excess ion polarisability on the capacitance of the electric double layer

Minton

Lue

2016

Molecular Physics

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This version is available at https://strathprints.strath.ac.uk/55894/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. We apply a modified Poisson-Boltzmann theory which permits ions of different sizes and excess polarizabilities to the study of these properties' effects on the differential capacitance of the electric double layer. For a planar electrode, we find an analytical expression for the differential capacitance, which is examined in the limits of low and high applied potential. In the low potential limit, a reduction of the solution relative permittivity caused by the ion polarizability causes the differential capacitance to decrease above a certain concentration, relative to the Gouy-Chapman-Stern theory. A similar effect is observed for the excluded volume, but only if the ions are of different sizes. In the high potential limit, the differential capacitance decreases inversely with the square root of the applied voltage. In a mixed electrolyte, asymmetries in both ion size and excess polarizability alter the surface adsorption of species: at high potentials, smaller ions displace larger ions and less polarizable ions displace more polarizable ions. The extent of the displacement agrees favorably with experimental data. A further consequence of this displacement is the appearance of a second peak in the differential capacitance, which is enhanced by excess ion polarizability.

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Effects of electrostatic correlations on electrokinetic phenomena

Cited by 152 publications

References 56 publications

Nonlinear electrophoresis in the presence of dielectric decrement

Nonlinear electrophoresis in the presence of dielectric decrement

Adsorption of charged and neutral polymer chains on silica surfaces: The role of electrostatics, volume exclusion, and hydrogen bonding

The influence of excluded volume and excess ion polarisability on the capacitance of the electric double layer

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