title: Speciation of indium(iii) chloro complexes in the solvent extraction process from chloride aqueous solutions to ionic liquids.
abstract: Most metal extraction studies focus on the kinetics, the maximum loading and the extraction equilibrium, while structural information on the extracted complexes has been limited. This paper concerns the nature of the indium(iii) chloride complexes, present in the organic and aqueous phase during the solvent extraction of indium(iii) from an aqueous HCl solution by undiluted ionic liquids Cyphos®IL 101 and Aliquat®336. In an aqueous HCl solution (0-12 M), indium(iii) exists as octahedral mixed complexes, [In(H2O)6-nCln]3-n(0 ≤ n ≤ 6). EXAFS and115In NMR were used to characterize these species. The stoichiometric composition of the extracted complexes, which is estimated from viscosity and maximum loading studies and confirmed by EXAFS, is unaffected by the HCl concentration in the aqueous phase. Indium(iii) is present in the ionic liquid phase as the tetrahedral [InCl4]-complex. Based on the speciation results an extraction mechanism is proposed.
authors.affiliation: KU Leuven, Department of Chemistry, Celestijnenlaan 200F, bus 2404, B-3001 Heverlee, Belgium. Koen.Binnemans@kuleuven.be and Umicore, Group Research & Development, Competence Area Recycling and Extraction Technologies, Watertorenstraat 33, B-2250 Olen, Belgium.
authors.forename: Clio
authors.initials: C
authors.lastname: Deferm
authors.affiliation: KU Leuven, Department of Chemistry, Celestijnenlaan 200F, bus 2404, B-3001 Heverlee, Belgium. Koen.Binnemans@kuleuven.be.
authors.forename: Bieke
authors.initials: B
authors.lastname: Onghena
authors.affiliation: KU Leuven, Department of Chemistry, Celestijnenlaan 200F, bus 2404, B-3001 Heverlee, Belgium. Koen.Binnemans@kuleuven.be.
authors.forename: Tom
authors.initials: T
authors.lastname: Vander Hoogerstraete
authors.affiliation: Dutch-Belgian Beamline (DUBBLE), ESRF - The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Banerjee
authors.affiliation: Umicore, Group Research & Development, Competence Area Recycling and Extraction Technologies, Watertorenstraat 33, B-2250 Olen, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Luyten
authors.affiliation: Umicore, Group Research & Development, Competence Area Recycling and Extraction Technologies, Watertorenstraat 33, B-2250 Olen, Belgium.
authors.forename: Harald
authors.initials: H
authors.lastname: Oosterhof
authors.affiliation: KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, bus 2450, B-3001 Heverlee, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Fransaer
authors.affiliation: KU Leuven, Department of Chemistry, Celestijnenlaan 200F, bus 2404, B-3001 Heverlee, Belgium. Koen.Binnemans@kuleuven.be.
authors.forename: Koen
authors.identifier: http://orcid.org/0000-0003-4768-3606
authors.initials: K
authors.lastname: Binnemans