Thermodynamic modeling of gas solubility in aqueous sodium chloride solution

Abstract

Abstract An electrolyte Equation of State is presented by combining the Cubic Plus Association Equation of State, Mean Spherical Approximation and the Born equation. This new model uses experimental relative static permittivity, intend to predict well the activity coefficients of individual ions (ACI) and liquid densities of aqueous solutions. This new model is applied to model water + NaCl binary system and water + gas + NaCl ternary systems. The cation/anion-water interaction parameters of are obtained by fitting the experimental data of ACI, mean ionic activity coefficients (MIAC) and liquid densities of water + NaCl binary system. The cation/anion-gas interaction parameters are obtained by fitting the experimental data of gas solubilities in aqueous NaCl solutions. The modeling results show that this new model can correlate well with the phase equilibrium and volumetric properties. Without gas, predictions for ACI, MIAC, and liquid densities present relative average deviations of 1.3%, 3.6% and 1.4% compared to experimental reference values. For most gas-containing systems, predictions for gas solubilities present relative average deviations lower than 7.0%. Further, the contributions of ACI, and salting effects of NaCl on gases are analyzed and discussed.