In this study, extraction of uranium(VI) from an aqueous nitric acid solution was investigated using tri-n-butyl phosphate (TBP) as an extractant in an ionic liquid, 1-alkyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide ([Cnmim][Tf2N]). The distribution ratio of U(VI) in 1.1 M TBP/[Cnmim][Tf2N] was significantly high when the concentration of nitric acid was low. The value of the distribution ratio decreased as the concentration of the nitric acid increased at lower acidities, and then increased with a nitric acid concentration of up to 8 M. This can be attributed to the different extraction mechanisms of U(VI) based on nitric acid concentrations. Thus, a cation exchange at low acidity levels and an ion-pair extraction at high acidity levels were suggested as the extraction mechanism of U(VI) in the TBP/[Cnmim][Tf2N] system.

1. Introduction
2. Experimental
    2.1 Reagents and apparatus
    2.2 Extraction procedure
3. Results and Discussion
    3.1 Kinetics of extraction
    3.2 Effect of aqueous phase acidity
    3.3 Mechanism of extraction
4. Conclusion
Acknowledgements
REFERENCES

• Ik-Soo Kim(Korea Atomic Energy Research Institute) Corresponding Author
• Dong-Yong Chung(Korea Atomic Energy Research Institute)
• Keun-Young Lee(Korea Atomic Energy Research Institute)