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. Bilogarithmic dependencies of distribution coefficients on the ligand concentration reveal non-integer slopes higher than those expected from saturation. Such features, very often observed for amides, can be explained by outer sphere coordination. Thus, two kinds of interactions were observed : - in the inner sphere of the metal : diamide-metal ion complexation; - in the outer sphere of the metal : diamide-metallic complex interactions.