Thermodynamics and phase separation of a de-ionized colloidal system in the symmetric Poisson-Boltzmann and mean spherical approximation theories

A model system of charged hard spheres and point counterions is used to analyze a de-ionized colloidal dispersion. Thermodynamic properties are calculated using a symmetric Poisson-Boltzmann equation, a linear form, and the Mean Spherical Approximation theory. The theories are found to predict a gas-liquid type transition and the spinodals computed. The results are compared among themselves and with recent Monte Carlo simulations for the model. (C) 2002 American Institute of Physics.