Gas-liquid critical point in ionic fluids

Abstract

Based on the method of collective variables we develop the statistical field theory for the study of a simple charge-asymmetric $1:z$ primitive model (SPM). It is shown that the well-known approximations for the free energy, in particular DHLL and ORPA, can be obtained within the framework of this theory. In order to study the gas-liquid critical point of SPM we propose the method for the calculation of chemical potential conjugate to the total number density which allows us to take into account the higher order fluctuation effects. As a result, the gas-liquid phase diagrams are calculated for $z=2-4$. The results demonstrate the qualitative agreement with MC simulation data: critical temperature decreases when $z$ increases and critical density increases rapidly with $z$.

18 pages, 1 figure

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• Vapor-liquid phase behavior of a size-asymmetric model of ionic fluids confined in a disordered matrix: the collective variables-based approach
• Phase behaviour in ionic solutions: restricted primitive model of ionic liquid in explicit neutral solvent
• Spatial inhomogeneities in ionic liquids, charged proteins and charge stabilized colloids from collective variables theory
• Vapour-liquid phase behaviour of primitive models of ionic liquids confined in disordered porous media
• Gas-liquid phase equilibrium in ionic fluids: Coulomb versus non-Coulomb interactions