Cd(II) plus iodide species were extracted into PEG-rich phases in the aqueous PEG(1550)-(NH4)2SO4 system at pH 2.05–7.12. IR spectra show that increasing (NH4)2SO4 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.
 A.E. Visser, S.T. Griffin, C.C. Ingenito, D.H. Hartman, J.G. Huddleston and R.D. Rogers: “Aqueous biphasic systems as a novel environmentally benign separation technology for metal ion removal”, Metal Sep. Technol. Beyond, (2000), pp. 119–130.
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