Evaluation of salting-out effect in the liquid-liquid equilibrium of aqueous two-phase systems composed of 2-propanol and Na2SO4/MgSO4 at different temperatures

Liquid-liquid equilibrium data (LLE) were obtained for aqueous two-phase systems (ATPS) composed of 2-propanol + inorganic salt (Na2SO4 or MgSO4) + water, at different temperatures T = (293.15, 303.15, 313.15 e 323.15) K. The effect of temperature on the binodal curves and tie-lines was studied. Temperature increase resulted in an expansion of the biphasic region, and this effect was more pronounced in the systems composed of 2-propanol + Na2SO4. A nonlinear equation was used to describe the binodal curves in terms of the mass fraction of 2-propanol versus sulfate salt. The effects of the different salts (Na2SO4 or MgSO4) on the phase-separation abilities of the studied ATPS was discussed using the values of parameters in the effective excluded volume (EEV) model. The salting-out abilities of the investigated salts followed the order Na2SO4 >MgSO4. The experimental results of LLE were correlated using the UNIFAC model. Calculated RMS deviations between the experimental and predicted LLE compositions for the 2-propanol + Na2SO4 and 2-propanol + MgSO4 systems were 1.76 and 0.68%, respectively. The UNIFAC model was able to effectively represent the studied biphasic aqueous systems.