EXTRACTION BY N,N,N',N'-TETRAALKYL-2-ALKYL-PROPANE-1,3-DIAMIDES .2. U(VI) AND PU(IV)

Extraction equilibria of U(VI) and Pu(IV) between aqueous nitric acid solutions and the diamide DMDBTDMA ((C4H9(CH3)NCO)2CHC14H29) dissolved TPH were investigated. Extraction takes place via the formation of L. UO2(NO3)2, L.Pu(NO3)4 and L2.Pu(NO3)4 for all the acidities. Bilogarit hmic dependencies of distribution coefficients on the ligand concentra tion reveal non-integer slopes higher than those expected from saturat ion. Such features, very often observed for amides, can be explained b y outer sphere coordination. Thus, two kinds of interactions were obse rved : - in the inner sphere of the metal : diamide-metal ion complexa tion; - in the outer sphere of the metal : diamide-metallic complex in teractions.