Prediction of phase equilibria with strong electrolytes with the help of the volume translated Peng-Robinson group contribution equation of state (VTPR)

The volume translated Peng-Robinson (VTPR) group contribution equation of state, which is commonly used for the prediction of phase equilibria with sub-critical as well as supercritical compounds, was extended to electrolyte systems by linking it with the group contribution model LIFAC. The approach was at first evaluated by applying it for the calculation of vapor–liquid equilibrium (VLE) data of binary and ternary systems with strong electrolytes (two solvents + one salt) using the available VTPR and LIFAC group interaction parameters. For the description of gas solubility data additional group interaction parameters (gas–ion interactions) are necessary. For fitting the required interaction parameters, a large number of gas solubility data are required. These data have been taken from published data stored in the Dortmund Data Bank. Typical results for the prediction of methane and carbon dioxide in aqueous electrolyte mixtures are presented over a wide concentration, temperature, and pressure range.