Cyphos nitrate: A potential ionic liquid for the extraction and selective separation of plutonium (IV) from other metal ions present in nitric acid

Cyphos nitrate (Trihexyl(tetradecyl)phosphonium nitrate: [P66614][NO3]) is a well-known ionic liquid which is strongly hydrophobic and sustainable for the recovery of metal ions from waste matrix. In the present study, the ionic liquid was explored for the selectively separation of plutonium(IV) from uranium(VI), zirconium(IV), americium(III) and europium(III) present in the nitric acid medium in conjunction with 1,3-diisopropyl benzene (DIPB) as the diluent. The extraction factors of Pu(IV) were evaluated as a function of various experimental parameters such as the concentration of feed acidity, the concentration of ionic liquid, equilibration time, temperature, type of ionic liquid ions, etc. Facile formation of the anionic nitrato complex of Pu(IV) in the ionic liquid phase was found to be the driving force for the preferential extraction of Pu(IV) over other metal ions. Effect of radiation dose suggested the stability of the proposed ionic liquid by acquiring the similar extraction factors like that in the unirradiated ionic liquid phase. Remarkable separation factors of Pu(IV) over the aforementioned metal ions were computed and presented in the paper. Various thermodynamic parameters accompanied by the extraction as well as the back extraction processes of Pu(IV) from the loaded ionic liquid phase have been presented in detail.