Gas solubility data of carbon dioxide (CO 2 ) in water (H 2 O) and aqueous sodium or potassium chloride (NaCl, KCl) solutions were measured by means of the static synthetic method in a temperature range from 313 to 393 K and pressures up to 10 MPa. The experimental data were compared to the results of other authors and to calculated values using an equation of state (EoS) approach. The calculations were enabled by the combination of the PSRK group contribution EoS with the LIFAC method for the prediction of vapor-liquid-phase equilibria containing strong electrolytes. The required interaction parameters were fitted to experimental data from this work and from the literature.

The g E model LIQUAC and the corresponding group contribution model LIFAC are widely used for the reliable prediction of vapor-liquid equilibria (VLE), osmotic coefficients, and mean ionic activity coefficients for aqueous systems that contain strong electrolytes up to high concentrations. These models consist of a Debye-Hückel term, a Pitzer type virial equation for the middle-range contribution, and the UNIQUAC, respectively, the UNIFAC term. However, with the variable reference state proposed herein, a reliable prediction of liquid-liquid equilibria (LLE) using the LIQUAC or the LIFAC model is not possible. Because the mean ionic activity coefficient in all existing liquid phases must be predicted reliably, an explicit fixed reference state for the ions had to be introduced for the normalization of the middle-range term. The aim of this work is to modify the LIQUAC and LIFAC model for the prediction of ternary LLE using interaction parameters based on binary datasets. In addition, the results for binary properties could be improved by further changes of the original models. Using a comprehensive database, the interaction parameters for the modified LIQUAC and the modified LIFAC model had to be refitted and the obtained results for the calculated properties of binary and ternary mixtures were finally compared to the results of the original models.

Gas solubility data of methane (CH4) in aqueous electrolyte solutions were measured using the static synthetic method in a temperature range from 313 to 373 K, at pressures up to 10 MPa, and with molalities up to 8 mol·(kg of water)-1. The experimental P − x data were used to fit interaction parameters for an equation of state approach, which consists of a combination of the predictive Soave−Redlich−Kwong (PSRK) group contribution equation of state and the LIFAC method for the prediction of vapor−liquid equilibria in systems with strong electrolytes. Furthermore, Henry coefficients were derived from these experimental P − x data and compared to the results of the extended PSRK model.

Liquid densities of several binary aqueous electrolyte mixtures and mixtures containing methanol and electrolytes were measured over a large range of concentrations and temperatures from 283 to 353 K using an oscillating-tube densitometer. From these values, molar volumes were calculated for all experimental data. A new empirical correlation method was introduced to determine densities and molar volumes using only two additional parameters, which were fitted for all ionic species investigated in this work. The experimental and calculated results are presented in comparison to results of other authors.

Isobaric vapor−liquid equilibrium data for the system methyl acetate (1) + methanol (2) + lithium nitrate (3) and ethyl acetate (1) + ethanol (2) + lithium nitrate (3) at constant salt molalities have been measured with the help of a modified Scott ebulliometer at 101.3 kPa and temperatures between 53 °C and 83 °C. The measured data were correlated using the electrolyte model LIQUAC.