Measurement and correlation of phase equilibria in aqueous two-phase systems containing functionalized magnetic ionic liquids and K2HPO4/K2CO3/Na2CO3 at 298.15 K

Functionalized magnetic ionic liquids (MILs)([C(2)TMG][TEMPO-OSO3], [C(3)TMG][TEMPO-OSO3], [C(4)TMG][TEMPO-OSO3]) and three inorganic salts (K2HPO4/K2CO3/Na2CO3) were used to form aqueous two-phase system at 298.15 K. Three classical experienced equations were applied for the correlations of the binodal curves. All of them demonstrated satisfactory performance in data association. The binodal curves were investigated in detail. Both K2HPO4 and K2CO3 was excellent phase forming salts for all the three MILs. Both of them can meet the need of practical applications. There is a narrow biphasic region for the MIL+ Na2CO3 + water system because of a relatively low solubility of salt in water. Additionally, tie-line data were experimentally obtained for the three MILs with K2HPO4 or K2CO3 at 298.15 K. Three empirical formulas including Othmer-Tobias equation, Bancroft equation together with another equation derived from binodal theory were used to fit the tie-line data. Consequently, Othmer-Tobias has shown ideal correlation performance and the reliability of our experimental tie-line data can be ensured. Hopefully, these aqueous two-phase equilibrium data should be useful in the areas of chemical separation, purification and analysis. (C) 2017 Elsevier B.V. All rights reserved.