Influence of solvent polarization and non-uniform ion size on electrostatic properties between charged surfaces in an electrolyte solution

Abstract

In this paper, we study electrostatic properties between two similar or oppositely charged surfaces immersed in an electrolyte solution by using the mean-field approach accounting for solvent polarization and non-uniform size effects. Applying a free energy formalism accounting for unequal ion sizes and orientational ordering of water dipoles, we derive coupled and self-consistent equations to calculate electrostatic properties between charged surfaces. Electrostatic properties for similarly charged surfaces depend on the counterion size but not on the coion size. Moreover, electrostatic potential and osmotic pressure between similarly charged surfaces are found to be increased with increasing counterion size. On the other hand, the corresponding ones between oppositely charged surfaces are related to both sizes of positive and negative ions. For oppositely charged surfaces, the electrostatic potential, number density of solvent molecules, and relative permittivity of an electrolyte having unequal ion sizes are not symmetric about the centerline between the charged surfaces. For either case, the consideration of solvent polarization results in a decrease in the electrostatic potential and the osmotic pressure compared to the case without the effect.

Ion-mediated charge-charge interactions drive aggregation of surface-functionalized gold nanoparticles

“…As such, this phenomenon is inherently local, leading to important conceptual and practical consequences. First, this behavior can't be described within the framework of the standard DLVO theory, and specific extension (as in other extended-DLVO theories [3][4][5] ) must be implemented if one wants to take this specific behavior into account. Second, this behavior can be exquisitely sensitive to kinetic processes such as NP surface ligand exchange, that could thus dynamically alter the propensity for NP aggregation over time 35 .…”

“…The DLVO theory is generally adequate for large particles or in the long-range regime, but at smaller ("nano") length scales, the continuum assumptions required by the DLVO theory break down. As a consequence, several discrepancies arise between the DLVO predictions and experimental results, due to deficiencies in the appropriate description of solvent polarization 2 , finite size of ions 3 , and hydration forces 4,5 . These discrepancies, generally defined as non-DLVO forces, can lead to unreliable predictions when the interparticle distance is less than 2 nm 1 .…”

Influence of solvent polarization and non-uniform ionic size on electrokinetic transport in a nanochannel

“…Based on these approaches, we studied several interesting phenomena related to multicomponent electrolytes (Sin et al 2016a), binary polar solvent mixtures (Sin et al 2016b), soft charged surfaces (Sin et al 2017) and electrostatic interaction between charged surfaces (Sin 2017).…”

“…It is worthwhile to mention that the solvent polarization effect has been extensively used to better represent biological interactions (Luque et al 1995), quantify electric double layer -mediated disjoining pressure between nanoscopically separated charged surfaces (Misra et al 2013;Sin 2017), study nitroethane deprotonation (Major et al 2005).…”

Steric effect of water molecule clusters on electrostatic interaction and electroosmotic transport in aqueous electrolytes: a mean-field approach

“…To derive the above formular we follow the corresponding one of 29 . Here we introduce the following dimensionless variables for more convenient determination of physical quantities:…”