Solid-liquid equilibria and thermodynamic correlation for the ternary system (KCl + PEG10000/20000 + H2O) at 288.2 K and 298.2 K

Abstract

This work finished measuring the phase equilibria of ternary systems {KCl + polyethylene glycol (PEG) 10000/20000 + H2O} at 288.2 and 298.2 K. The solubility, density and refractive index were determined and corresponding diagrams were plotted in this work. There was only solid–liquid phase equilibrium existing in the ternary systems {KCl + PEG10000/20000 + H2O} at 288.2 K and 298.2 K. All of the phase diagrams of four systems are divided into three parts which respectively are the regions of unsaturated homogeneous liquid (L), one liquid and one solid KCl (L + S), and one liquid and two solids KCl and PEG (L + 2S). In addition, the effects of molar mass of PEG (PEG1000/4000/10000/20000) and temperature (288.2 K and 298.2 K) on phase equilibria were discussed. Results show that the sizes of regions of (L) and (L + S) increased and that of (L + 2S) decreased with the increase of temperature, and the regions of (L) and (L + S) decreased and that of (L + 2S) increased with the increase of the molar mass of PEG. The modified Pitzer model was adopted as the equilibrium thermodynamics model to correlate the experimental data. Comparing the experimental data and calculated dada, it can give a precise result with small error.