No abstract

The predictive Soave−Redlich−Kwong (PSRK) model widely used for the prediction of vapor−liquid equilibria and gas solubilities of nonelectrolyte systems was extended to electrolyte systems by the incorporation of the LIFAC model (electrolyte group contribution g E model) used to calculate the excess Gibbs energy of electrolyte systems in the g E mixing rule. Four new groups (charged or ionic groups Na+, NH4 +, Ca2+, and Cl-) were added to the already existing 73 noncharged UNIFAC and PSRK main groups. The group interaction parameters between the new and already existing groups were fitted using gas solubility data for electrolyte solutions stored in the Dortmund Data Bank. Typical results for CO2, N2, and CH4 solubilities predicted by the PSRK model are presented for various saltwater systems over a wide temperature and pressure range and different salt concentrations.

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.

Using gas−liquid chromatography (GLC), activity coefficients at infinite dilution have been measured for 37 solutes (alkanes, alkenes, cyclic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, ethers, aldehydes, esters, and halocarbons) in the solvents dimethyl sulfoxide, propylene carbonate, and N-ethylformamide. The measurements were carried out in the temperature range between 303.15 and 333.15 K. The obtained γ∞ values are compared with published data, and the observed temperature dependence of the limiting activity coefficients is confirmed using excess enthalpy data. Furthermore, the selectivities and capacities of the investigated solvents for the separation of aliphatics from aromatics are compared.