Effects of electrostatic correlations on electrokinetic phenomena
Name
Storey-2012-Effects of electrostatic correlations on electrokinetic phenomena.pdf
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367.28 KB
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Author(s)
Storey, Brian D.
Bazant, Martin Z.
Date Issued
November 2012
Journal
Physical Review E
Publisher
American Physical Society
Citation
Storey, Brian D., and Martin Z. Bazant. “Effects of Electrostatic Correlations on Electrokinetic Phenomena.” Physical Review E 86.5 (2012). ©2012 American Physical Society
Version
Final published version
Abstract
The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture subtle aspects of molecular simulations and allows for simple calculations of electrokinetic flows in correlated ionic fluids. Charge-density oscillations tend to reduce electro-osmotic flow and streaming current, and overscreening of surface charge can lead to flow reversal. These effects also help to explain the suppression of induced-charge electrokinetic phenomena at high salt concentrations.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mathematics
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevE.86.056303
