Equation of state for electrolyte aqueous solution based on perturbation theory

Using perturbation theory, an equation of state was built for electrolyte solution in which a mixture of charged hard spheres and uncharged hard spheres was used as the reference system, and intermolecular forces such as dispersion, dipolar, and induction forces were considered. The densities for 22 single-, 9 binary- and 1 quaternary-electrolyte aqueous solutions at different temperatures were calculated using water parameters and ionic diameters. Also, the densities of NaCl solution at 25 300 and 0.1 100 MPa were calculated. The calculation precision was good. The results show that this equation of state is suitable for calculating densities of single and mixed electrolyte solutions in wide ranges of temperatures and pressures. No empirical parameter is needed when this equation is used for high temperatures and high pressures or for mixed electrolyte solutions.