Phase behavior of ionic liquids-cesium carbonate-water aqueous two-phase systems and their extraction of L-tryptophan

Phase behavior and extraction ability of aqueous two-phase systems(ATPs) consisting of ionic liquids(ILs), Cs 2 CO 3 and water were investigated in this paper. Four kinds of ionic liquids, namely, 1-amyl-3-methylimidazolium bromide([C 5 mim]Br), 1-hexyl-3-methylimidazolium bromide([C 6 mim]Br), 1-heptyl-3-methylimidazolium bromide ([C 7 mim]Br) and 1-octyl-3-methylimidazolium bromide([C 8 mim]Br), were examined to discuss the influence of alkyl groups. Binodal curves and tie-lines at 288.15, 298.15 and 308.15 K were obtained. The partitioning behavior for L -tryptophan in such ATPs was further investigated. The effect of temperature, pH, Cs 2 CO 3 concentration and the structure of ionic liquids on the partitioning were discussed in detail.