Selective Separation of Neptunium from an Acidic Feed Containing a Mixture of Actinides Using Dialkylamides

Abstract

ABSTRACTExtraction of Np(IV), Pu(IV), U(VI), and Np(VI) was studied using N,N-di-2-ethylhexyl derivatives iso-butyramide (D2EHIBA) and n-propanamide (D2EHPrA). D2EHIBA showed higher selectivity for U(VI) over Np(IV) and Pu(IV). A flowsheet for the separation of Np(IV) from a mixture of uranium, neptunium, and plutonium in 3 M HNO3 was developed exploiting the selectivity of D2EHIBA for U(VI) over the tetravalent actinides followed by the selective stripping of Np(IV) from the di-n-hexyl-octanamide (DHOA) medium using acetohydroxamic acid (AHA). The results indicated that >90% of the neptunium present in the mixture could be recovered at the final step with a decontamination factor >103.