resumo
Among the numerous and interesting features of ionic liquids is their ability to form aqueous biphasic systems (ABSs) when combined with inorganic or organic salts in aqueous media. In this work, a wide range of salts was studied, aiming at gathering a detailed picture on the molecular mechanisms that govern the ability of the salt ions to induce the formation of ionic-liquid-based ABSs. For that purpose, 1-butyl-3-methylimidazolium trifluoromethanesulfonate was chosen due to its facility to undergo liquid-liquid demixing in aqueous media containing conventional salts. The corresponding ternary phase diagrams, tie-lines, and tie-line lengths were determined at 298 K and atmospheric pressure. With the large body of data measured in this work, it was possible to establish a scale on the salt cation and anion abilities to induce the formation of ionic-liquid-based ABSs, which follows the Hofmeister series, and to show that the molar entropy of hydration of the salt ions is the driving force for aqueous two-phase system formation.
palavras-chave
2-PHASE SYSTEMS; DIFFERENT TEMPERATURES; MUTUAL SOLUBILITIES; PHASE-BEHAVIOR; SALTING-OUT; PLUS WATER; EXTRACTION; GLYCOL); EQUILIBRIUM; SEPARATION
categoria
Chemistry
autores
Shahriari, S; Neves, CMSS; Freire, MG; Coutinho, JAP
nossos autores
Catarina Maia Seco Seiça Neves
Investigador Auxiliar
Mara Guadalupe Freire Martins
Investigador CoordenadorGrupos
G4 - Materiais Renováveis e Economia Circular
G5 - Materiais Biomiméticos, Biológicos e Vivos
Projectos
agradecimentos
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/LA0011/2011. The authors also acknowledge FCT for the postdoctoral and doctoral grants SFRH/BPD/41781/2007 and SFRH/BD/70641/2010 of M.G.F. and C.M.S.S.N., respectively.