Screening of ion–ion correlations in electrolyte solutions adsorbed in electroneutral disordered matrices of charged particles: Application of replica Ornstein–Zernike equations

Abstract

The replica Ornstein–Zernike (ROZ) equations for an ionic fluid adsorbed in an electroneutral, disordered matrix of ions were applied to a model where both ionic subsystems were presented as point charges interacting only via Coulomb forces. The effects of fluid (electrolyte) and matrix concentration on the screening of the ion–ion interactions in the fluid phase were investigated. The effects of the prequenching conditions were also examined. It was shown that augmenting the matrix concentration promotes attraction between equally charged ions and repulsion between ions of opposite sign. This peculiar behavior, observed first in the simulation study of Bratko and Chakraborty [J. Chem. Phys. 104, 7700 (1996)], follows straightforwardly from the ROZ equations. Moreover, we generalized the expression for the disorder averaged ion–ion potential for an arbitrary fluid concentration and prequenching conditions. In addition to these results, which are consistent with computer studies, we present some new results that have not been observed in simulations. For example, alternating ionic ordering, generated by the influence of the charged matrix was observed. This contribution can be considered as a first step toward a study of primitive model electrolytes adsorbed in disordered matrices of hard-sphere ions. The solution of this problem will be presented elsewhere.

The Screening Potentials of Ion-Dipole System Adsorbed in Ion-Dipolar Disordered Matrices

“…The results obtained for ion-ion screening potential coincide with the result [8] only for the case ε 0 = 1. In order to understand the reason of such difference we consider ionic mean force potentials at the infinite dilution of ions which play the role of interionic potentials for considering the system in the McMillan-Mayer level of a description [11].…”

“…In this way Given and Stell [1][2] recently proposed a set of coupled integral equations, the so-called replica Ornstein-Zernike (ROZ) equations, relating the total pair correlation functions h αβ (r) of fluid-matrix mixture to the corresponding direct For this time the application of ROZ equations was restricted the description of simple fluids in random and quenched matrices [3][4][5][6].Only recently a study of associating fluids [6][7] and ionic fluids [8][9] in porous media using ROZ equations was initiated. In particular, in [8] the ROZ equations were applied for the investigation of the screening potentials for the proposed in [10] model of ionic fluids adsorbed in an electroneutral totally disordered matrix of ion.…”

“…In particular, in [8] the ROZ equations were applied for the investigation of the screening potentials for the proposed in [10] model of ionic fluids adsorbed in an electroneutral totally disordered matrix of ion. In this model both ionic subsystems were presented as point charges interacting via Coulomb interactions.…”

Fluids confined in porous media: An ideal gas in different matrices

“…Although equation (150) looks formally identical to equation (51), the matrix density in these two equations have different meanings [compare equations (52) and (149)]. Nevertheless, for the same value of matrix density and the same matrix particle size, the thermodynamics of an IG is the same no matter whether it is adsorbed in a HS Madden-Glandt matrix or in a Van Tassel templated matrix generated from a binary HS mixture.…”

Application of Replica Ornstein-Zernike equations in studies of the adsorption of electrolyte mixtures in disordered matrices of charged particles

“…The thermodynamic and structural properties of these systems can be calculated using the computer simulations and/or the replica integral equation theories. This work presents the continuation of our previous studies of partly quenched systems containing charges [18][19][20][21][22][23][24][25]. The quenched "phase" (we shall call it the matrix) is some frozen (quenched) equilibrium distribution of a symmetric model +1:−1 electrolyte.…”