The development and applications of ABEC resins.

摘要

Aqueous biphasic systems (ABS) represent wholly aqueous systems. Their aqueous nature, over 80% water on a molar basis, makes them excellent candidates for green separation processes. Due to their environmentally benign nature, these systems have been applied to the separation of a wide variety of solute molecules ranging from macromolecules and small organic solutes to metal ions. However, the major disadvantage of ABS systems is the difficulty in the back-extraction, or recovery, of the partitioned solute.;We have overcome this disadvantage by covalently attaching polyethylene glycol (PEG) polymers to a solid support. By utilizing a salt solution as the mobile phase with these resins in a column mode, an ABS-like condition is achieved, and separations normally observed in ABS can be observed in these resins. When the mobile phase is changed to a salt solution that does not support biphase formation, ABS conditions are not met, and any solute retained on the resin can be simply washed away. Thus, stripping can now be achieved by simply eluting with water! Because of the strong relationship of these materials with PEG-ABS, we prefer to name this separation technique Aqueous Biphasic Extraction Chromatography or ABEC.;The strong relationship between ABS and ABEC has been discussed in detail. ABEC behavior correlates to ABS behavior with two notable exceptions. First, ABEC resins can retain certain metal ions without the presence of a phase forming salt. Second, the distribution ratios of the pertechnetate anion decrease with increasing temperature for ABEL, while the distribution ratios increase for ABS. A procedure has been outlined to express ABEC in terms of equivalent ethylene oxide concentration in order to compare the two methods on the same terms.;The application of ABEL resins to several real world separations has been successfully demonstrated. These applications include the removal of 99TcO4− from radioactive tank waste, the separation of 188ReO4− from its parent 188WO42−, the separation of iodide from urine samples, the separation of metal ions in hydrometallurgical solutions, and the removal of Hg2+ from ground and tap water solutions.