Thermodynamic modeling of CO2 solubility in aqueous solutions of NaCl and Na2SO4

A thermodynamic model based on the electrolyte NRTL activity coefficient equation and PC-SAFT equation-of-state is developed for CO2 solubility in aqueous solutions of NaCl and Na2SO4 with temperature up to 473.15 K, pressure up to 150 MPa, and salt concentrations up to saturation. The Henryʹs constant parameters of CO2 in H2O and the characteristic volume parameters for CO2 required for pressure correction of Henryʹs constant are identified from fitting the experimental gas solubility of CO2 in pure water with temperature up to 473.15 K and pressure up to 150 MPa. The NRTL binary parameters for the CO2–(Na+, Cl−) pair and the CO2–(Na+, SO42−) pair are regressed against the experimental VLE data for the CO2–NaCl–H2O ternary system up to 373.15 K and 20 MPa and the CO2–Na2SO4–H2O ternary system up to 433.15 K and 13 MPa, respectively. Model calculations on solubility and heat of solution of CO2 in pure water and aqueous solutions of NaCl and Na2SO4 are compared to the available experimental data of the CO2–H2O binary, CO2–NaCl–H2O ternary and CO2–Na2SO4–H2O ternary systems with excellent results.