Th(IV) and U(VI) removal by TODGA in ionic liquids: extraction behavior and mechanism, and radiation effect
- 60 Downloads
Extraction behavior of thorium(IV) and uranium(VI) from nitric acid (HNO3) was studied using N,N,N′,N′-tetraoctyldiglycolamide (TODGA) as extractant in different ionic liquids, and isooctane as comparison. Slope analyses with varying HNO3 concentrations and diluents revealed the extraction mechanism. With increasing length of alkyl chain and HNO3 concentration, the extraction mechanism of TODGA/IL system changed from cation exchange to neutral complex and/or anion exchange, and the molar ratio between TODGA and metal ions varied gradually from 2:1 to 1:1 for Th(IV) and 3:1 to 1:1 for U(VI). The kinetics and thermodynamic studies of Th(IV) and U(VI) by the best TODGA/[C2mim][NTf2] system showed that the extraction equilibrium was reached within 2 h and extraction reactions were endothermic. Compared to TODGA/isooctane system, TODGA/[C2mim][NTf2] system presented higher radiation stability under γ-irradiation. Therefore, it would have a promising application in spent fuel reprocessing.
KeywordsExtraction TODGA Ionic liquids Thorium(IV) and uranium(VI) Radiation effect
- 2.E. Merle-Lucotte, D. Heuer, M. Allibert et al., Introduction to the physics of molten salt reactors, in Materials Issues for Generation IV Systems. NATO Science for Peace and Security Series B: Physics and Biophysics, ed. by V. Ghetta, D. Gorse, D. Mazière et al. (Springer, Dordrecht, 2008), pp. 501–521. doi: 10.1007/978-1-4020-8422-5_25
- 3.A.M. Dodson, R.A. McCann, Investigation of thermal feedback design for improved load-following capability of thorium molten salt reactors, in: Green Technologies Conference, 2013, IEEE (IEEE, 2013), pp. 215–219. doi: 10.1109/GreenTech.2013.40
- 17.T. Mori, K. Takao, K. Sasaki et al., Homogeneous liquid-liquid extraction of U(VI) from HNO3 aqueous solution to betainium bis(trifluoromethylsulfonyl)imide ionic liquid and recovery of extracted U(VI). Sep. Purif. Technol. 155, 133–138 (2015). doi: 10.1016/j.seppur.2015.01.045 CrossRefGoogle Scholar
- 28.W.J. Yuan, Y.Y. Ao, L. Zhao et al., gamma-ray induced radiolysis of [C(2)mim][NTf2] and its effects on Dy3+ extraction. Nucl. Sci. Tech. 26, 92–96 (2015)Google Scholar