Selective separation of zirconium(IV) from uranium(VI) using dioxoamide ligand present in ammonium based ionic liquid: An application towards spent metallic fuel reprocessing

Abstract

The alloy of an actinide (U or Pu) with zirconium (6%) has been proposed as metallic fuel. The removal of zirconium from the dissolver solution is required prior to the separation of actinides during reprocessing. In this context, the extraction behavior of zirconium was studied in a solution of 2-ethylhexyl- and the decyl-derivative of benzodioxodiamide, abbreviated as BD and BDD, respectively, in ionic liquid medium. Instead of the conventional imidazolium ionic liquid that displayed several drawbacks, strongly hydrophobic ionic liquids such as methyltributylammonium bis(trifluoromethylsulfonyl)imide ([N1444][NTf2]) and methyltrioctylammonium bis(trifluoro-methylsulfonyl)imide ([N1888][NTf2]) have been employed, as a diluent, in conjunction with the BD and BDD ligands for the extraction of Zr(IV). The effect of nitric acid concentration in aqueous phase, duration of equilibration, interference of uranium and the effect of temperature on the extraction of Zr(IV) in BD present in ionic liquid was studied. The number of BD-ligands involved in the extraction of zirconium was determined. The results showed the possibility of removing zirconium from the bulk quantity of uranium present in the dissolver solution.