(Liquid + liquid) equilibria and extraction capacity of (imidazolium ionic liquids + potassium tartrate) aqueous two-phase systems

To explore the large range of aqueous two-phase system (ATPS) applications, ionic liquid (IL) and organic salt have been recently reported to be able to form ATPS. They could thus be interesting media in biotechnological applications for the separation and purification of biomolecules. In this work, phase diagrams and tie-lines for the 1-butyl-3-methylimidazolium chloride ([C4mim]Cl)/1-hexyl-3-methylimidazolium chloride ([C6mim]Cl)/1-benzyl-3-methylimidazolium chloride ([C7H7mim]Cl)-K2C4H4O6 ILATPSs at 298.15 K were measured and presented. It is shown that the larger the cation alkyl chain is, the greater is the IL's ability for ATPS formation, meanwhile the slope of tie-line increases with the increase of cation alkyl chain length. In addition, the extraction capacity of the studied ILATPSs was evaluated through their application to the extraction of chloramphenicol. The partition coefficient of CAP obtained in the IL-K2C4H4O6 ILATPS is followed in the order: [C6mim]Cl > [C4mim]Cl > [C7H7mim]Cl. Moreover, the CAP easily enters the top phase with the increase of temperature of the systems and initial concentration of the solute.