Departamento de Química, CICECO, Universidade de Aveiro , 3810-193 Aveiro, Portugal.
J Phys Chem B. 2014 Jan 9;118(1):297-308. doi: 10.1021/jp411933a. Epub 2013 Dec 23.
Two main approaches were combined aiming at evaluating the impact of polyvalent salt cations on the formation of ionic-liquid-based aqueous biphasic systems (ABS): (i) experimental determination of a large array of ternary phase diagrams composed of sodium-, magnesium-, and aluminum-based salts with 1-butyl-3-methylimidazolium-based ionic liquids and (ii) determination of the ions speciation in each of these systems. The results here reported show, for the first time, that the phase behavior of ionic-liquid-based aqueous biphasic systems is not only dominated by the ability of the strong and "free" salting-out ions to interact with water creating thus hydration complexes but also a result of the interactions occurring between the different ions and, particularly, on their speciation in aqueous solutions. The gathered data indicate that the higher the salt ion valence, the more complex is its speciation with a number of different species in aqueous media present. Further results based on NMR spectroscopy and a proper analysis of the pH influence clearly demonstrated the impact of ion speciation through the phase separation and ABS formation.
两种主要方法相结合，旨在评估多价盐阳离子对离子液体基双水相体系（ABS）形成的影响：（i）实验测定由钠离子、镁离子和铝离子基盐与 1-丁基-3-甲基咪唑鎓基离子液体组成的大量三元相图，以及（ii）确定这些体系中每个体系的离子形态。这里报告的结果首次表明，离子液体基双水相体系的相行为不仅由强“游离”盐析离子与水相互作用形成水合配合物的能力决定，而且还由不同离子之间的相互作用决定，特别是它们在水溶液中的形态决定。收集的数据表明，盐离子价数越高，其在水溶液中存在的不同物种的形态越复杂。进一步基于 NMR 光谱和对 pH 值影响的适当分析的结果清楚地证明了离子形态通过相分离和 ABS 形成的影响。
