Direct separation of minor actinides from high level liquid waste by Me 2 -CA-BTP/SiO2-P adsorbent

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

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.

Synthesis of soft N-donor isoPentyl-BTBP and study on its removal of actinides from high level liquid waste

To directly separate actinides from high level liquid waste (HLLW), a novel molecule, i. e. isoPentyl-BTBP (6,6′-bis(5,6-bis(4-methylpentyl)-1,2,4-triazin-3-yl)-2,2′-bipyridines) was synthesized and characterized. A kind of isoPentyl-BTBP/SiO2-P adsorbent was obtained by impregnating isoPentyl-BTBP into porous silica/polymer support particles SiO2-P under reduced pressure. The effect of HNO3 concentration, contact time on the adsorption of isoPentyl-BTBP/SiO2-P towards 241Am(III) and 239Pu(IV) was studied. And the stability of isoPentyl-BTBP/SiO2-P in HNO3 medium was also evaluated. It turned out that isoPentyl-BTBP/SiO2-P had much higher affinity for 241Am(III) and 239Pu(IV) over FP elements in 3 M HNO3, fast adsorption kinetics towards 239Pu(IV), excellent stability in HNO3 medium, and should be a very promising adsorbent for separating 239Pu(IV) and 241Am(III) from HLLW.

Separation of trivalent actinides and lanthanides using various ‘N’, ‘S’ and mixed ‘N,O’ donor ligands: a review

Separation of trivalent actinide (An) and lanthanide (Ln) elements is one of the burning topics in the back end of the nuclear fuel cycle due to the similarity in their chemical behaviour. A significant amount of research is being carried out worldwide to develop suitable ligands for the separation of the trivalent actinides and lanthanides. Some of the research groups are engaged in continuous improvement of the di-ethylene-triamine-penta acetic acid (DTPA) based Ln/An separation method, whereas extensive research is going on for the development of the lipophilic and hydrophilic ‘N’ donor heteropolycyclic ligands as the actinide selective ligand. A number of ‘S’ donor ligands are also explored for the Ln/An separation. In the present review, we made an attempt to highlight various separation processes based on soft donor ligands developed for Ln/An separations. Beside the conventional solvent extraction processes, separation possibilities membrane based and solid phase extraction techniques are evaluated for the Ln/An separation and are compiled in the present review.