Salting-out effect of sodium, potassium, carbonate, sulfite, tartrate and thiosulfate ions on aqueous mixtures of acetonitrile or 1-methyl-2-pyrrolidone: A liquid-liquid equilibrium study

The binodal curves, tie-line compositions and cloud point data as a function of temperature and concentration were measured for aqueous two phase systems composed of acetonitrile (ACN) + K2CO3 + H2O, ACN + Na2CO3 + H2O, 1-methyl-2-pyrrolidone (NMP) + K2CO3 + H2O and NMP+ Na2CO3 + H2O. Additionally, salting-out ability of sodium sulfite, sodium thiosulfate and sodium tartrate was studied. The free energy, enthalpy and entropy of clouding point (CP) estimated using a simple method, and the driving force of the two-phase formation process was discussed on the base of the estimated free energy values. Also, an empirical equation was modified as a function of organic solvents density and dielectric constants and used for the simultaneous correlation of all experimental binodal data. Furthermore, e-NRTL and e-Wilson models were used for the correlation of tie-line compositions. The obtained results confirm the high performance of these models in the correlation of binodal and tie-line data. (C) 2013 Elsevier B.V. All rights reserved.