Nanofluidic charge transport under strong electrostatic coupling conditions

Abstract

The comprehensive depiction of the many-body effects governing nanoconfined electrolytes is an essential step for the conception of nanofluidic devices with optimized performance. By incorporating self-consistently multivalent charges into the Poisson-Boltzmann equation dressed by a background monovalent salt, we investigate the impact of strong-coupling electrostatics on the nanofluidic transport of electrolyte mixtures. We find that the experimentally observed negative streaming currents in anionic nanochannels originate from the collective effect of the Cl attraction by the interfacially adsorbed multivalent cations, and the no-slip layer reducing the hydrodynamic contribution of these cations to the net current. The like-charge current condition emerging from this collective mechanism is shown to be the reversal of the average potential within the no-slip zone. Applying the formalism to surface-coated membrane nanoslits located in the giant dielectric permittivity regime, we reveal a new type of streaming current activated by attractive polarization forces. Under the effect of these forces, the addition of multivalent ions into the KCl solution sets a charge separation and generates a counterion current between the neutral slit walls. The adjustability of the current characteristics solely via the valency and amount of the added multivalent ions identifies the underlying process as a promising mechanism for nanofluidic ion separation purposes.

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• Nanofluidics, from bulk to interfaces
• Nanofluidics coming of age
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• Strong-Coupling Theory for Counter-Ion Distributions
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• Electrostatics of ions inside the nanopores and trans-membrane channels
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• Virial expansion for charged colloids and electrolytes

Cited by in corpus (5)

• Explicit Solvent Theory of Salt-Induced Dielectric Decrement
• Systematic incorporation of the ionic hard-core size into the Debye-Huckel theory via the cumulant expansion of the Schwinger-Dyson equations
• Dielectric manipulation of polymer translocation dynamics in engineered membrane nanopores
• Theoretical and computational analysis of the electrophoretic polymer mobility inversion induced by charge correlations
• Interactions between polyelectrolytes mediated by ordering and orientation of multivalent non-spherical ions in salt solutions