Vapour-liquid critical parameters of a $2$:$1$ primitive model of ionic fluids confined in disordered porous media

TL;DR

This study investigates how a disordered porous medium affects the vapour-liquid critical parameters of a 2:1 ionic fluid model, revealing that charge asymmetry influences the impact of the medium.

Contribution

It extends the theoretical analysis of ionic fluids in porous media to the 2:1 valency case, highlighting the effects of charge asymmetry and particle sizes on critical behavior.

Findings

Critical temperature and density trends are similar to monovalent cases.

Ion charge asymmetry weakens the matrix's influence on critical parameters.

Porosity and particle size significantly affect phase coexistence.

Abstract

We study the vapour-liquid critical parameters of an ionic fluid confined in a disordered porous medium by using the theory which combines the collective variables approach with an extension of the scaled particle theory. The ionic fluid is described as a two-component charge- and size-asymmetric primitive model, and a porous medium is modelled as a disordered matrix formed by hard-spheres obstacles. In the particular case of the fixed valencies $2$:$1$, the coexistence curves and the corresponding critical parameters are calculated for different matrix porosities as well as for different diameters of matrix and fluid particles. The obtained results show that the general trends of the reduced critical temperature and the reduced critical density with the microscopic characteristics are similar to the trends obtained in the monovalent case. At the same time, it is noticed that an ion charge asymmetry significantly weakens the effect of the matrix presence.