Phase stability estimated for adhesive charged sphere fluids with an analytical solution

Abstract

Phase separation, which can occur in a fluid mixture system (FMS) containing adhesive charged hard spheres (ACHSs) by the addition of a salt of pointlike ionic species, can be enhanced by increasing the absolute value of the charge z0e on the ACHS. Phase stability in the FMS can be revealed using an analytical solution based on the mean spherical approximation for the Ornstein–Zernike equation and can behave nonlinearly. For such a phenomenon, the effect given by the potential of mean force plays an important role. When the adhesive interaction between ACHSs is weak in an FMS containing ACHSs of low charge and low density, an increase in |z0e| can stabilize the dispersed state of the FMS. When each of the ACHSs reaches a highly charged state, the increase in |z0e| can enhance phase separation. When the adhesive interaction between ACHSs is strong in an FMS containing ACHSs of low charge, the stability of the dispersed state depends nonlinearly on the volume fraction φ of ACHSs. The clusters of the ACHSs resulting from phase separation can completely dissolve when φ reaches a certain value as φ increases.