abstract
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): (1) 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.
keywords
SOLVENT RELAXATION PROCESSES; 2-PHASE SYSTEMS; 298.15 K; POLYETHYLENE-GLYCOL; PHASE-BEHAVIOR; SALTING-OUT; COUNTERCURRENT CHROMATOGRAPHY; IMIDAZOLIUM TETRAFLUOROBORATE; VIBRATIONAL-RELAXATION; MUTUAL SOLUBILITIES
subject category
Chemistry
authors
Kurnia, KA; Freire, MG; Coutinho, JAP
our authors
Kiki Adi Kurnia
Post-doc Fellowship
Mara Guadalupe Freire Martins
Coordinating ResearcherGroups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
G6 - Virtual Materials and Artificial Intelligence
Projects
acknowledgements
This work was financed by national funding from FCT-Fundacao para a Ciencia e a Tecnologia, through the projects PTDC/QUI-QUI/121520/2010 and Pest-C/CTM/LA0011/2013. Kiki A. Kurnia also acknowledges FCT for the postdoctoral grant SFRH/BPD/88101/2012 and Mara G. Freire for the FCT 2012 Investigator Programme.