Theoretical Insights into the Substitution Effect of Phenanthroline Derivatives on Am(III)/Eu(III) Separation

Abstract

Separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) poses a huge challenge in the reprocessing of spent nuclear fuel due to their similar chemical properties. N,N′-Diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) is a potential ligand for the extraction of An(III) from Ln(III), while there are still few reports on the effect of its substituent including electron-withdrawing and electron-donating groups on An(III)/Ln(III) separation. Herein, the interaction of Et-Tol-DAPhen ligands modified by the electron-withdrawing groups (CF3, Br) and electron-donating groups (OH) with Am(III)/Eu(III) ions was investigated using scalar relativistic density functional theory (DFT). The analyses of bond order, quantum theory of atoms in molecules (QTAIM), and molecular orbital (MO) indicate that the substitution groups have a slight effect on the electronic structures of the [M(L-X)(NO3)3] (X = CF3, Br, OH) complexes. However, the thermodynamic results suggest that a ligand with the electron-donating group (L-OH) improves the extraction ability of metal ions, and the ligand modified by the electron-withdrawing group (L-Br) has the best Am(III)/Eu(III) selectivity. This work could render new insights into understanding the effect of electron-withdrawing and electron-donating groups in tuning the selectivity of Et-Tol-DAPhen derivatives and pave the way for designing new ligands modified by substituted groups with better extraction ability and An(III)/Ln(III) selectivity.

Heterocyclic Ligands with Different N/O Donor Modes for Am(III)/Eu(III) Separation: A Theoretical Perspective

“…Thermodynamics of Extraction Reactions. On the basis of previous works, 30,33 ). The Gibbs free energy changes (ΔG) for the reactions in n-dodecane were calculated at the B3LYP/6-311G(d,p)/RECP level of theory (see Table 5).…”

Combined Experimental and Theoretical Insights on Selectivity of Rare Earth Elements with Tetra‐2‐ethylhexyl Diglycolamide

“…[37][38] The calculation with Eu 3 + was carried out using septet spin state and sextet spin state was used for Fe-complexes during the optimization of the structure and energy calculation. [39][40][41][42] The free energy was evaluated at 298.15 K [43] using standard methods at the B3LYP level of calculations due to its ability to provide reliable thermodynamic properties of lanthanides. [44][45] Conductor like screening model (COSMO) was adopted to represent the liquid state of water, IDA and dodecane phase [46][47] having di-electric constant of 80, 8 and 2 respectively.…”

A Simple yet Efficient Hydrophilic Phenanthroline-Based Ligand for Selective Am(III) Separation under High Acidity

“…This high-level liquid waste (HLLW) is then subjected to the partitioning and transmutation (P&T) process to separate the radioactive minor Ans chemically and transmute them into short-lived nuclides though neutron bombarding. The prerequisite for P&T lies in the efficient separation of Lns from Ans due to the large neutron cross section of Lns. ,− …”