Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The liquid-liquid equilibrium (LLE) for 2-propanol + tripotassium phosphate+ water at 298.15, 308.15, and 318.15 K and 2-propanol +dipotassium hydrogen phosphate + water at 298.15 K, were measured. The binodal curves of 2-propanol + potassium sulfate / potassium sulfite + water at 298.15 K, were measured and compared. Accordingly, the experimental binodal data were correlated using Merchuk, Hu, and Pirdashti equations and the tie-line compositions were correlated using Othmer-Tobias and Bancroft equations. The effect of temperature, anion type, and the length of alcohol chain on the binodal curve, tie-line length (TLL), the slope of tie-line (STL), and the phases' physical properties were studied. It was found that an increase in salt's hydrophobicity and alcohol's carbon number in low temperature led to the expanding biphasic region and approaching the binodal curve to the origin. The phase-forming ability of different anions was studied using effective excluded volume (EEV) model and the relation between the EEV value, saturation solubility, anion's surface charge density, and salt solubility in water was investigated. It was found that kosmotropic ions with higher surface charge density and lower solubility in water has higher EEV value and able to form wider two-phase area. Finally, the salting-out ability of different alcohols was compared with the Setschenow-type equation and found that increasing the carbon number of alcohols enable the ATPS salt out effectively.