abstract
In this work, the ability of Na(2)SO(4) and ionic liquids to induce the formation of acidic aqueous two-phase systems (ATPS) is investigated. Ternary phase diagrams, tie lines, and tie-line lengths for several systems were determined and reported at 298 K and atmospheric pressure. It is here shown that among the ionic liquids studied only those containing long alkyl side chains at the ions and/or anions with low hydrogen bond basicity are capable of undergoing liquid-liquid demixing in the presence of Na(2)SO(4) aqueous solutions. The results obtained indicate that, besides the salting-out ability of the inorganic salt, the pH of the aqueous solution plays a crucial role toward the formation of ionic-liquid-based ATPS. In acidic media the range of ionic liquids that are able to undergo ATPS formation is substantially reduced when compared to alkaline aqueous salt solutions. The use of inorganic salts and ionic liquids to promote acidic ATPS is envisaged as particularly valuable in the extraction of compounds that exhibit low acid dissociation constants.
keywords
BIPHASIC SYSTEMS; 1-BUTYL-3-METHYLIMIDAZOLIUM BROMIDE; MUTUAL SOLUBILITIES; 298.15 K; EXTRACTION; SALTS; WATER; SEPARATION; EQUILIBRIA; PYRIDINIUM
subject category
Chemistry
authors
Claudio, AFM; Ferreira, AM; Shahriari, S; Freire, MG; Coutinho, JAP
our authors
Ana Filipa M. Cláudio
Post-doc Fellowship
Ana Maria Ferreira
Researcher
João Manuel Costa Araújo Pereira Coutinho
Vice-Director
Mara Guadalupe Freire Martins
Research Coordinatoracknowledgements
A.F.M.C. and M.G.F. acknowledge Fundacao para a Ciencia e a Tecnologia for the doctoral grant SFRH/BD/74503/2010 and the postdoctoral grant SFRH/BPD/41781/2007, respectively.