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

ABSTRACT

The phase diagrams and the liquid-liquid equilibrium (LLE) data of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) + tripotassium citrate and 1-butyl-3-methylimidazolium bromide ([C4mim]Br) + trisodium citrate aqueous two-phase systems (ATPS s) were determined experimentally at T = (278.15, 298.15, and 318.15) K. The Merchuk equation with three dependent-temperature adjustable parameters was used for reproducing the binodal curves. In the studied systems, the salting-out effect caused by the addition of the inorganic salts to the aqueous solutions of the water-miscible ionic liquids (ILs) was investigated. The effects were analyzed using the corresponding composition phase diagrams. The effect of temperature on the phase-forming ability in the investigated systems was also evaluated based on a salting-out coefficient obtained from fitting the tie-line data to a Setschenow-type equation. The values of the salting-out coefficients may reflect the extent of the preferential hydration of the IL. Furthermore, the salting-out effect and the consequent phase separation in the investigated ATPS s were interpreted taking into account the complex and competing nature of the interactions between the solutes and water. Finally, the intensity of the phase-forming ability in the [C4mim]X (X = Cl- or Br-) + salt ATPS s was also examined on the basis of the ionic viscosity B-coefficients of the Jones-Dole equation.