A novel phosphoramide task specific ionic liquid for the selective separation of plutonium (IV) from other actinides

A novel phosphoramide task specific ionic liquid, diethyl-3-(-3-butylimidazolium)propylphosphoramide bis(trifluoromethanesulfonyl)imide ([BuImPA][NTf2]), was synthesized and characterized by NMR and FTIR spectroscopy, for the first time. The extraction behavior of Pu(IV), U(VI) and Am(III) from nitric acid medium was studied by using [BuImPA][NTf2] dissolved in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]). The extraction was studied as a function of various parameters such as concentration of nitric acid, extractant concentration, temperature, alkyl chain length attached to imidazolium moiety etc. The distribution ratio of Pu(IV) in [BuImPA][NTf2]/[C4mim][NTf2] increased with increase in the concentration of nitric acid, reached a maximum at 5 M nitric acid followed by a plateau. In contrast to this, the distribution ratio of U(VI) in [BuImPA][NTf2] was quite less and showed a decreasing trend. The extraction of Am(III) was insignificant at all nitric acid concentrations. As a consequence, the separation factor of Pu(IV) over U(VI) and Am(III) achieved with the use of [BuImPA][NTf2]/[C4mim][NTf2] varied from 10 to 103, respectively. The extraction stoichiometry of Pu(IV)-[BuImPA][NTf2] was determined by the slope analysis of extraction data. The recovery of Pu(IV) from loaded organic was studied and the results are reported in this paper.