Salt Effects on Liquid–Liquid Equilibria of Water + Phenol + (Propan-2-yl) Benzene + Salts Systems

The effect of three dissolved salts, namely, sodium chloride, sodium sulfate, and magnesium sulfate, on the liquid–liquid equilibrium of phenol extraction from aqueous phase by (propan-2-yl) benzene (cumene) was investigated at the temperature of 298.2 K and the ambient pressure of 81.5 kPa. Salts with mass fractions of 0.005 and 0.020 in water were used and significant enhancement in the phenol extraction was achieved compared to salt-free system. Results showed that the presence of salts caused the solute separation factor to reach as (46.29 and 95.81)% with NaCl, (63.52 and 165.19)% with Na2SO4, and (86.39 and 238.55)% with MgSO4, related to the used low and high salt concentrations. Therefore, the salting-out effect appeared in the order MgSO4 > Na2SO4 > NaCl, in agreement with the Hofmeister series. The Eisen–Joffe equation confirmed the consistency of experimental tie-line data. To correlate the obtained data, the well-known NRTL and UNIQUAC thermodynamic models were satisfactorily used and the maximum root-mean-square deviations were as low as 0.0071 and 0.0013 for these models, respectively.