Phase Equilibria of the Ternary Systems Potassium Sulfate + Polyethylene Glycol (PEG6000/10,000) + Water at 288.2, 298.2 and 308.2 K: Experimental Determination and Correlation

Abstract

The phase equilibrium data were determined for the ternary systems potassium sulfate + polyethylene glycol (PEG6000/10,000) + water at 288.2, 298.2 and 308.2 K. Only solid–liquid equilibrium exists for the ternary system K2SO4 + PEG6000/10,000 + H2O at 288.2 and 298.2 K, the solubility, density, and refractive index were measured by using the isothermal dissolution equilibrium method. The solid–liquid equilibrium and liquid–liquid equilibrium exist simultaneously for the ternary system K2SO4 + PEG6000/10,000 + H2O at 308.2 K, the corresponding compositions of binodal curve and tie-line were obtained experimentally by using the turbidimetric method. Results show that the solubility of K2SO4 decreases as the content of PEG increases in the PEG–H2O mixed solvents. Meanwhile, as the molar mass of PEG increased, the liquid–liquid equilibrium formed more easily and the liquid–liquid equilibrium area was larger. In addition, the modified Pitzer model was used to calculate the solid–liquid equilibrium data for systems K2SO4 + PEG6000/10,000 + H2O at 288.2, 298.2 and 308.2 K.