Modeling of Gas Solubility in Aqueous Electrolyte Solutions using the Electrolyte Cubic-Plus-Association Equation of State
Prediction of the solubilities for carbon dioxide and methane in aqueous inorganic salt solutions plays a key role in geological carbon storage, enhanced oil recovery and seawater desalination.
And accuracy solubility calculations for carbon dioxide and methane in aqueous solutions of quaternary ammonium salts are important for semi-clathrate hydrate formation, There are a few electrolyte Equation of State (EOS) for gas solubility calculation in wide temperature-pressure-salt molality (T-P-m) ranges.
This work presents a thermodynamic modeling study for gas solubilities of carbon dioxide and methane in several aqueous solutions with the electrolyte Cubic-Plus-Association (e-CPA) EOS [1, 2].
The ion-gas interaction parameters are obtained by fitting the experimental data of gas solubilities. The model is extended to multi-salt solution systems with single salt-gas interaction parameters, and the model performance for these multi-salt systems is similar with that of single salt solutions.
The modeling results show that e-CPA can satisfactorily correlate gas solubilities in wide T-P-m ranges, with deviation around 7% for most systems. Compared with other electrolyte EOS, e-CPA can give better performance in wide T-P-m ranges.
The salting-out effects and the effect of various factors (ion size, charge density, salt concentration) are also discussed, based on experimental data and the calculated values from e-CPA.