Electrolyte Cubic Square-Well Equation of State for Computation of the Solubility of CO2 in Aqueous Salt Solutions

The electrolyte cubic square-well (eCSW) equation of state of Haghtalab and Mazloumi is used o study the solubility of CO2 in aqueous salt solutions in the wide range of concentration, pressure, temperature. This electrolyte equation of state is composed of the mean spherical approximation (MSA) theory, the Born equation and a cubic square-well equation of state (SWEOS). Calculations of the vapor-liquid equilibrium of the H2O-CO2 and the H2O-CO2 -salt systems are performed using the electrolyte eCSW EOS so that the binary molecular interaction parameters kij, in the combining rule of EOS, for the pairs of ion-H2O and ion-CO2 are optimized by the six scenarios. Using electrolyte SWEOS, the solubility of CO2 in aqueous binary solutions of the different salts such as NaCl, KCl, Na2SO4, MgSO4, MgCl2 and CaCl2 is calculated. A Vapor- Liquid Equilibrium algorithm is applied to obtain the best binary interaction parameters using optimization of solubility of CO2 in aqueous electrolyte solutions. In comparison to the experiment, the results demonstrate that the eCSW EOS is able to obtain the solubility data of ternary aqueous electrolyte systems with very good accuracy