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

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 K(2)SO(4)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.