Polyethylene glycol (PEG) chemistry: Partitioning of chaotropic ions in PEG-based aqueous biphasic systems and structural investigation of lanthanide isothiocyanate/PEG complexes

This work probes polyethylene glycols (PEGs) as the basis for a new extraction technology for metal ions. The combination of PEG with a suitable salt in sufficient concentrations forms aqueous biphasic systems (ABS) suitable for separating various solutes. This study shows that a salt's anion determines whether an aqueous biphasic system will form when a PEG is mixed with the salt in water. The characterization (phase diagrams, dispersion numbers, viscosities, etc.) of a number of aqueous biphasic systems has been systematically carried out.The difficulty in stripping the ionic solutes from the loaded polymer-rich phases in ABS has been overcome for pertechnetate using the reducing reagent SnClSmall chain polyethylene glycols have been investigated as complexing ligands for lanthanide using lanthanide(III) isothiocyanates as the starting salts. The oxygen donors of the acyclic PEGs readily coordinate the lanthanides. Most of the studied complexes are nine-coordinate with a tricapped trigonal prismatic geometry. In addition, the possibility of the thiocyanate anion (NCSThis study demonstrates that ABS are a powerful technology for separations of the ionic solutes. Fundamental studies have been performed in order to understand partitioning of chaotropic ions in ABS using...