(99a) Thermodynamic Modeling of CO2 Solubility in Aqueous Solutions of NaCl, KCl, CaCl2, MgCl2 and Their Mixed Salts Using ENRTL Model

The influence of electrolytes on phase equilibria of CO2 is important to various chemical, petroleum, and environmental applications including CO2 capture and sequestration. A thermodynamic model based on the electrolyte NRTL activity coefficient equation and PC-SAFT equation-of-state is developed for CO2 solubility in aqueous NaCl, KCl, CaCl2, and MgCl2solutions at temperatures from 273 to 473 K, pressures up to 150 MPa, and salt concentrations up to saturation. Effects of different electrolyte species on CO2 solubility in aqueous solutions have been investigated. The eNRTL binary interaction parameters for the CO2–ion pair are regressed against the experimental CO2 solubility data for aqueous single electrolyte solutions. Additionally, the solubility of CO2 in aqueous solutions of mixed electrolytes including NaCl + KCl, NaCl + CaCl2 , KCl + CaCl2), NaCl+MgCl2, KCl+MgCl2 and CaCl2+MgCl2 (each at weight ratio = 1:1) are predicted with the eNRTL binary parameters. the prediction results favorably agree with the experimental values.