Aqueous polymeric solutions as environmentally benign liquid liquid extraction media

Several liquid-phase extraction technologies employing environmentally beni gn phase- or micelle-forming polymers in aqueous solution have the potentia l to replace volatile organic compounds in classical solvent extraction tec hnologies. The examples reviewed here include aqueous biphasic system's, cl oud-point extraction, micellar extraction, and thermoseparating polymer sys tems. The apparent similarities of these systems, their phase-separating pr operties, and their ability to solubilize a wide variety of solutes ranging from metal ions, organic compounds, and biologicals are discussed. Some co mparative data from the literature whereby the solvating power of these sys tems may be compared to traditional solvents are presented along with new d ata on the polarity of the phases in typical aqueous biphasic systems. The need for additional comparative data in this area and the need to demonstra te the validity of the approach in operational processes are emphasized. A "toolbox" approach to implementing environmentally benign polymers in clean separations science and technology could lead to new and better solvent ex traction systems.