title: Metal ion separations in polyethylene glycol-based aqueous biphasic systems: correlation of partitioning behavior with available thermodynamic hydration data.
abstract: Solvent extraction utilizing an oil-water mixture (e.g., chloroform-water) and a suitable complexant, is a proven technology for the selective removal and recovery of metal ions from aqueous solutions. Aqueous biphasic systems (ABS), formed by mixing certain inorganic salts and water-soluble polymers, or by mixing two dissimilar water-soluble polymers, have been studied for more than 40 years for the gentle, non-denaturing separation of fragile biomolecules, yet ABS have been virtually ignored as a possible extraction technology for metal ions. In this report we review our metal ion partitioning work and discuss the three major types of partitioning: (1) those rare instances that the metal ion species present in a given solution partitions to the PEG-rich phase without an extractant; (2) the use of halide salts which produce a metal anion complex that partitions to the PEG-rich phase; and (3) the use of a water-soluble extractant which distributes to the PEG-rich phase. In addition, we correlate the partitioning behavior we observed with available thermodynamic data for metal ions and their complexes.
authors.affiliation: Department of Chemistry, Northern Illinois University, DeKalb, 60115, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Rogers
authors.forename: A H
authors.initials: AH
authors.lastname: Bond
authors.forename: C B
authors.initials: CB
authors.lastname: Bauer
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: S T
authors.initials: ST
authors.lastname: Griffin
mesh_terms: D016014:Linear Models; D008670:Metals / Q000737:chemistry*; D009994:Osmolar Concentration; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D008670:Metals; D011108:Polymers; D012492:Salts; D012997:Solvents; D014867:Water; D011092:Polyethylene Glycols; D013670:Sodium Pertechnetate Tc 99m