The influence of 1-butyl-3-methyl-imidazolium bromide on the partitioning of l-tyrosine within the {polyethylene glycol 600 + potassium citrate} aqueous biphasic system at T = 298.15 K

• [C4mim]Br effect on the partitioning of Tyr in {PEG 600 + K3C6H5O7} ABS was studied.
• Partition of Tyr into the PEG-rich phase was enhanced using [C4mim]Br as an adjuvant.
• [C4mim]Br was also preferentially partitioned into the PEG-rich top phase.
• The LLE and partitioning data were satisfactorily correlated by the NRTL model.

Partitioning in aqueous biphasic systems (ABS) is widely recognized today as a rapid, gentle, and highly efficient technique for the separation of soluble as well as particulate biomaterials. This technique has gained increasing attention as the separation method of choice in biotechnology. In recent years, a new approach has been proposed based on the use of ionic liquids (ILs) as adjuvants for the separation and purification of bio-molecules using polymer-based ABS. In this regard, the influence of IL 1-butyl-3-methylimidazolium bromide ([C4mim]Br) on the phase behavior and extraction capability of {PEG 600 + tri-potassium citrate (K3C6H5O7)} ABS for l-tyrosine (Tyr) is investigated here. For this purpose, phase diagrams and the liquid–liquid equilibrium (LLE) data for the {PEG 600 + K3C6H5O7} ABS with the addition of small quantities of IL were determined at T = 298.15 K. It was found that, for the studied polymer-based ABS, the addition of 5 wt% of [C4mim]Br to ABS caused the expansion of two-phase area in the salt-rich region; while, for the PEG-rich region no change was observed. The partition coefficients of l-tyrosine (KTyr) within the studied system were determined at T = 298.15 K. The results obtained indicate that the addition of small quantities of [C4mim]Br to the {PEG 600 + K3C6H5O7} ABS could enhance the extraction efficiency for l-tyrosine. In addition, the experimental data are correlated using the NRTL model. The comparisons between the correlation and the experimental data reveal a good agreement.