Separation of curium from europium by cloud point extraction using 8-hydroxyquinoline

NUCL 13

Troy A Robinson, robin212@unlv.nevada.edu, Harry Reid Center Radiochemistry Group, University of Nevada, Las Vegas, 4505 Maryland Pkwy, Box 454009, Las Vegas, NV 89154-4009, Ken Czerwinski, czerwin2@unlv.nevada.edu, Department of Chemistry, University of Nevada, Las Vegas, 4505 Maryland Parkway, Box 454003, Las Vegas, NV 89154-4003, and Micheline Draye, Micheline.Draye@univ-savoie.fr, Laboratoire de Chimie Moléculaire et Environnement Polytech'Savoie, Université de Savoie Campus Scientifique, 73376 Le Bourget du Lac Cedex, France.
A recent extension of cloud point extraction separations of lanthanides has shown that the method offers some degree of separation of the trivalent actinides from the lanthanides. Current studies show that curium can be extracted in solutions containing europium to yield heavy phases that are enriched in curium. The current system under development uses triton X-114, a surfactant, 8-hydroxyquinoline (8-HQ), a chelator, and nitric acid to adjust the pH. The system shows no extraction at pH 5.0 (pKa1 of 8-HQ = 5.13), but shows increased extraction as pH increases over range of pH of 5.7–6.5. Concentrations of 8-HQ examined are 0–4.5 mM. These concentrations correspond to a ratio of [8-HQ]:[total metal] of 0–14.3. Initial tests show that metals extracted into the surfactant rich phase can be back-extracted to the surfactant poor phase by decreasing pH of aqueous phase to around pH 2.5.