title: Selective extraction of metal ions from aqueous phase to ionic liquids: a novel thermodynamic approach to separations.
abstract: The selective extraction of metals from aqueous mixtures has generally relied on the use of selective ionophores. We present an alternative strategy that exploits a recently developed approach to extraction into an ionic liquid phase, and show that a high degree of control over selectivity can be obtained by tuning the relative concentrations of extraction agents. A thermodynamic model for the approach is presented, and an experimental separation of strontium and potassium ions is performed. It is shown that tuning the concentrations of the species involved can shift the ratio of potassium to strontium in the ionic liquid phase from 4:1 to 3:4. This extraction is performed under mild conditions with relatively common reagents. The result is a proof-of-concept for a novel separations scheme that could have great importance in a wide range of technological applications.
authors.affiliation: Process Equipment Department of Process & Energy, Faculty of Mechanical, Maritime & Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft (The Netherlands); Wetsus Centre of Excellence for Sustainable Water Technology, Agora 1, 8900 CC, Leeuwarden (The Netherlands).
authors.forename: Camiel H C
authors.initials: CH
authors.lastname: Janssen
authors.forename: Antonio
authors.initials: A
authors.lastname: Sánchez
authors.forename: Mark N
authors.initials: MN
authors.lastname: Kobrak
keywords: ionic liquids; metal extraction; thermodynamics; water purification