CATION-EXCHANGE BEHAVIOR OF BERKELIUM IN AQUEOUS-ORGANIC SOLUTIONS OFNITRIC-ACID, CONTAINING TRIOCTYLPHOSPHINE OXIDE

Behavior of transplutonium elements (TPEs), Eu, and Zr on Dowex-50 cat ion-exchange resin in aqueous-organic solutions of HNO3 containing tri octylphosphine oxide (TOPO) has been studied as influenced by the natu re of the solvent (H2O, CH3OH, C2H5OH, CH3COOH, CH3CN), the compositio n and concentration of various components of the solution, and the pre sence of an oxidant (PbO2) in the resin phase. We found that the facto rs of Bk distribution between the PbO2-containing resin and CH3CN-HNO3 -TOPO solutions are considerably lower than the distribution factors o f other TPEs, which is due to oxidation of Bk(III) into Bk(IV). This f act can be used for separation of Bk(IV) from other TPEs with a cation -exchange column containing an oxidant. The optimal conditions of sepa ration (elution with solutions containing 1.0-2.5 M HNO3, 0.1 M TOPO, and 80-90% CH3CN) have been determined. A mechanism is proposed for TP E sorption on the cation-exchange resin from aqueous-organic solutions of HNO3 containing TOPO. The analogy between behavior of TPEs in ion- exchange and extraction processes in these systems is discussed.