Distribution of ions near a charged selective surface in critical binary solvents

TL;DR

This paper investigates how near-critical binary solvent mixtures with ions behave near charged surfaces, revealing that critical adsorption significantly alters ion distribution and impacts electrostatic screening.

Contribution

It extends the Landau-Ginzburg approach to include electrostatics and solvent preference, providing a simple correction to Debye-Huckel theory for ion profiles near charged surfaces.

Findings

Critical adsorption affects ion distribution near charged walls.

The correction modifies the classical Debye-Huckel charge density profile.

Implications for electrostatic screening in near-critical solvents.

Abstract

Near-critical binary mixtures containing ionic solutes near a charged wall preferentially adsorbing one component of the solvent are studied. Within the Landau-Ginzburg approach extended to include electrostatic interactions and the chemical preference of ions for one component of the solvent, we obtain a simple form for the leading-order correction to the Debye-Huckel theory result for the charge density profile. Our result shows that critical adsorption influences significantly distribution of ions near the wall. This effect may have important implications for the screening of electrostatic interactions between charged surfaces immersed in binary near-critical solvents.