A novel highly selective ligand for separation of actinides and lanthanides in the nuclear fuel cycle. Experimental verification of the theoretical prediction. Issue 33 (2nd August 2017)

• Record Type: Journal Article
• Authors: Lavrov, H. V.; Ustynyuk, N. A.; Matveev, P. I.; Gloriozov, I. P.; Zhokhov, S. S.; Alyapyshev, M. Yu.; Tkachenko, L. I.; Voronaev, I. G.; Babain, V. A.; Kalmykov, S. N.; Ustynyuk, Yu. A.
• Is Part Of: Dalton transactions. Volume 46:Issue 33(2017)
• Page Start: 10926
• Page End: 10934
• Publication Date: 2017-08-02
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt01009e
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Predicted by DFT simulation dilactams (B ) are selective and efficient extractants for the separation of Eu 3+ and Am 3+ . Abstract : We have predicted earlier by DFT simulation that tridentate O, N, O-donor cyclic dilactams (B ) belonging to the family of pyridine-2, 6-dicarboxamides are much more selective and efficient extractants for the separation of lanthanides and actinides than open-structure pyridine-2, 6-dicarboxamides due to the higher degree of "ligand preorganization". In the present work, three new ligands of type (B ) were synthesized. Extraction experiments showed that, in line with the data from DFT simulation, these ligands have 5–6-fold higher selectivity for the separation of an Am 3+ /Eu 3+ pair and provide distribution coefficients D which are by three orders of magnitude higher than those for the related parent ligands with an open structure. Determination of the solvate numbers (SNs) for Eu 3+ and Am 3+ cations by slope analysis has shown that the stoichiometry of complexes, in the form of which these ions pass from the aqueous into the organic phase, depends to a considerable extent on the polarity of the organic solvent. Strongly polar solvents ( ε > 20) extract these cations mainly in the form of 1 : 1 complexes LM(NO3 )3 having according to the DFT simulation the largest dipole moments ( μ = 18.6–19.7 D). The solvents of low polarity ( ε ≤ 10) extract these cations mainly in the form of less polar 2 : 1 complexes L2 M(NO3 )3 ( μ ≈ 1.6 D). For solvents of intermediate polarity fractional values of solvate numbers were obtained which indicates the coexistence of complexes LM(NO3 )3 and L2 M(NO3 )3 in the organic phase.