Synthesis and evaluation of N,N-di-alkyl-2-methoxyacetamides for the separation of U(VI) and Pu(IV) from nitric acid medium

Abstract

Abstract The homologs of N,N-di-alkyl-2-methoxyacetamides (DAMeOA) having three different alkyl chains varying from hexyl to decyl (C6, C8 and C10) were synthesized and characterized by NMR and IR spectral analyses. Extraction behavior of U(VI) and Pu(IV) from nitric acid medium in a solution of 0.5 M of DAMeOA in n-dodecane (n-DD) was studied and the results were compared with those obtained using N,N-di-hexyloctanamide (DHOA) in n-dodecane. The effect of various parameters on the distribution ratio of U(VI) and Pu(IV) in DAMeOA was studied. The extraction of nitric acid increased with decrease in chain length of alkyl group attached to amidic nitrogen atom of DAMeOA and the conditional nitric acid extraction constant was determined. The extraction of nitric acid in DAMeOA/n-DD resulted in the formation of third phase in organic phase and the third phase occurred early with DAMeOA having smaller alkyl chain length. In contrast to this, the distribution ratio (D) of U(VI) and Pu(IV) in DAMeOA/n-DD increased with increase in the concentration of nitric acid and with increase in the chain length of alkyl group attached to amidic nitrogen atom of DAMeOA. The stoichiometry of the metal – solvate was determined from the slope of extraction data. Quantitative recovery of uranium and plutonium from the loaded organic phase was achieved using dilute nitric acid.