Experimental studies and modeling of CO₂ solubility in high temperature aqueous CaCl₂, MgCl₂, Na₂SO₄, and KCl solutions

The phase equilibria of CO₂ and aqueous electrolyte solutions are important to various chemical-, petroleum-, and environmental-related technical applications. CO₂ solubility in aqueous CaCl₂, MgCl₂, Na₂SO₄, and KCl solutions at a pressure of 15 MPa, the temperatures from 323 to 423 K, and the ionic strength from 1 to 6 mol kg^-1 were measured. Based on the measured experimental CO₂ solubility, the previous developed fugacity-activity thermodynamic model for the CO₂-NaCl-H₂O system was extended to account for the effects of different salt species on CO₂ solubility in aqueous solutions at temperatures up to 523 K, pressures up to 150 MPa, and salt concentrations up to saturation. Comparisons of different models against literature data reveal a clear improvement of the proposed PSUCO2 model in predicting CO₂ solubility in aqueous salt solutions.