Cd(II) extraction in PEG-based two-phase aqueous systems in the presence of iodide ions.: Analysis of PEG-rich solid phases

Cd(II) plus iodide species were extracted into PEG-rich phases in the aqueous PEG(1550)-(NH4)(2)SO4 system at pH 2.05 - 7.12. IR spectra show that increasing (NH4)(2)SO4 solution acidity does not protonate PEG ether oxygen atoms, but decreases water content in the PEG-rich phases. Metallic species' extraction into the PEG predominantly alters how water molecules bind to polymer chains; the changes in their absorption bands depend on pH. Microscopy shows that "fixation" of the extracted metal in the PEG-rich phase occurs by specific interactions which depend on the species. These also determine changes in the polymer chains' conformation. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.