The solid–liquid equilibrium of the binary system H2O–DMSO and the influence of a salt (NaCl, KCl) on the thermodynamic behavior: Correlations using a revised LIQUAC model

The solid–liquid equilibrium of the binary system water (H2O)–dimethyl sulfoxide (DMSO) is investigated and the results are compared to experimental values to ensure that the applied measurement procedure provides reliable results. After that, the freezing point depression of water is measured in the presence of different amounts of salt. Furthermore solubility measurements are carried out and compared to published experimental data to show that the apparatus used is also capable to provide reliable results for salt solubilities. Afterwards the ternary system is investigated using this measurement procedure to determine the solubilities of the salt in the mixed solvent system as well as the freezing point depression of the mixed solvents after the addition of salt. Two salts are investigated, sodium chloride (NaCl) and potassium chloride (KCl). Most of the measured ternary data seems to be reported for the first time. A correlation of the experimental results is also carried out using a revised version of the electrolyte model LIQUAC.

► A method for the measurement of salt solubilities and freezing points is presented.
► The solid–liquid equilibrium of DMSO–H2O + salt (NaCl, KCl) is measured.
► A revised LIQUAC model is presented. Experimental data are correlated with the revised LIQUAC model.
► Results of the model are given for different electrolyte properties.