Phase diagrams have been measured for the ternary systems KCl + PEG + H2O and NaCl + PEG + H2O at 298.15 K and 313.15 K and for the quaternary system NaCl + KCl + PEG + H2O at 298.15 K. In all the cases PEG of molecular weight 4000 has been used. Density, refractive index and electrical conductivity were also determined for all the saturated solutions at 298.15 K. Equations are proposed in order to correlate the equilibrium and physical properties data of the ternary systems at 298.15 K. At 298.15 K, the PEG addition decreases the solubility of all the experimental systems and only one liquid phase in equilibrium with solid phase is found. In the quaternary system, the presence of two salts decreases the individual salt solubility values, being this effect more important for KCl. At 333.15 K, both ternary systems contain a region with two liquid phases in equilibrium, where a liquid is rich in salt and the other one in PEG. The liquid−liquid-solid equilibrium was determined for both systems. The field of crystallization of the corresponding salt is bigger at 298.15 than to 333.15 K. Similar behavior for both salts, KCl and NaCl was found.

The partitioning of iodide was studied in an aqueous biphasic system (ABS) comprised of ammonium sulfate, polyethylene glycol (PEG), and water at 25 °C. The average molecular weights of PEG were (2078, 3819, and 9887) g·mol-1. In a prior determination, data for the liquid−liquid equilibrium of this system were obtained and correlated with the nonrandom, two-liquid (NRTL) thermodynamic model. Data on the partition coefficients and percentage extraction of iodide were obtained , which were correlated as a function of the concentration gradient of the PEG between the phases and the average molecular weight of the PEG. The fit equation obtained had a mean deviation of 0.0171 and a mean error of 1.89 %.