Additional considerations about the role of ion size in charge reversal

Abstract

The effect of the ion size on the charge reversal process is studied via canonicalMonte Carlo simulation. To this end, a primitive model of electrolyte is usedto analyze the electric double layer formed by an asymmetric electrolyte in thepresence of a charged planar wall. Different values of ion diameters and surfacecharge densities are used so as to determine the conditions at which the chargereversal first occurs. For each case, the apparent surface charge density is calculatedas a function of the distance from the charged wall for the different electrolyteconcentrations in order to establish the minimal salt concentration required for the chargereversal. We will refer to this electrolyte concentration as the reversal concentrationand will show how it depends on the surface charge density and on the ion size.From the apparent surface charge density profiles, the distance from the wallat which the charge reversal arises as well as its intensity can be also inferred.