Experimental connections between aqueous-aqueous and aqueous-ionic liquid biphasic systems

Aqueous-ionic liquid (A-IL) biphasic systems containing deuterated water, deuterated nitric acid (10(-2) M to 7 M) and either [C(1)C(4)im(+)][Tf2N-], [C(1)C(10)im(+)][Tf2N-] or [Me3BuN+][Tf2N-] have been examined in terms of water and acid solubilities in the IL-rich phase and in terms of IL cation and anion solubilities in the water-rich phase. Other experiments focused on the IL cation and anion solubility in the water-rich phase upon addition of either [C(1)C(4)im(+)][Cl-] or [Li+][Tf2N-]. The results evidence a complex interplay between all negatively and positively charged ions of the samples that could be described following the usual approach used for aqueous-aqueous (A-A) biphasic systems. Other examples from the literature are discussed and demonstrate that the frontier between A-A and A-IL systems is questionable. Predictions are made for the extraction of metallic ions by use of biphasic systems in this work that are successfully compared to literature data.