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The liquid-liquid equilibria (LLE) data were experimentally measured for the partially miscible systems of n-propanol-water-NaCl, n-propanol-water-NaBr, n-propanol-water-KCl, and i-propanol-water-NaCl at 25 °C. A method of calculation for the prediction of the salting effect on the LLE of organic aqueous solutions was proposed to correlate the experimental tie-line data. In the proposed method, the activity coefficients of the solvents were calculated by Tan's modified Wilson model which was combined with a vapor pressure model of electrolyte solutions, and the mean ionic activity coefficient was calculated by the Gibbs-Duhem equation. The parameters required by the proposed method could be estimated by the vapor pressures of a water-salt system and the alcohol-water interaction parameters in the liquid-phase activity coefficient model. No ternary parameter was required. The proposed method has been used to predict the LLE data measured by this work, and the overall average deviation of tie-line compositions was 0.018.

The membrane potentials across cation- and anion-exchange membranes were measured for five LiBr−various-solvent systems. Water, dimethyl sulfoxide, ethylene glycol, methanol, and n-propanol were used as the solvents in this work. The experimental data were analyzed on the basis of the Donnan equilibrium and the Nernst−Planck equation of ion flux considering the effect of ion pairing of the electrolyte in the external solution. The Fuoss formalism of ion pairing was adopted to estimate the effective ion concentration in the external solutions, and the theoretical predictions agreed well with the experimental data. The effective membrane charge densities and the cation-to-anion mobility ratios in the membrane were also determined in this work. The results showed that the effective membrane charge density will vary with the kind of solvent. We attempted to introduce the concept of ion pairing inside the membrane to clarify this phenomenon.

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