Ion-pair extraction of uranyl ion from aqueous medium using crown ethers

Ion-pair extraction behaviour of uranyl ion from aqueous solutions was stud ied at pH 3.0 employing crown ethers viz. benzo 15 crown 5 (B15C5), 18 crow n 6 (18C6), dibenzo 18 crown 6 (DB18C6), and dibenzo 24 crown 8 (DB24C8) in chloroform as the organic phase and picric acid as the organophilic counte r anion. The stoichiometry of the extracted species corresponded to [UO2(cr own ether)(n)](2+).[pic(-)](2) where n = 1.5 for benzo 15 crown 5 and 1 for 18 crown 6 as well as dibenzo 18 crown 6. Adducts of DB24C8 could not be o bserved as practically no extraction was possible using this reagent. The s eparation behaviour of fission products from an irradiated uranium target w as also studied. An interesting observation on the separation of trivalent lanthanides from uranyl ion is reported. (C) 1998 Elsevier Science B.V. All rights reserved.