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Critical assessment of the formation of ionic-liquid-based aqueous two-phase systems in acidic media.

Authors
  • Cláudio, Ana Filipa M
  • Ferreira, Ana M
  • Shahriari, Shahla
  • Freire, Mara G
  • Coutinho, João A P
Type
Published Article
Journal
The Journal of Physical Chemistry B
Publisher
American Chemical Society
Publication Date
Sep 29, 2011
Volume
115
Issue
38
Pages
11145–11153
Identifiers
DOI: 10.1021/jp204865a
PMID: 21846140
Source
Medline
License
Unknown

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.

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