Hydrophilic Clicked 2,6-Bis-triazolyl-pyridines Endowed with High Actinide Selectivity and Radiochemical Stability: Toward a Closed Nuclear Fuel Cycle

Abstract

There is still an evident need for selective and stable ligands able to separate actinide(III) from lanthanide(III) metal ions in view of the treatment of the accumulated radioactive waste and of the recycling of minor actinides. We have herein demonstrated that hydrophilic 2,6-bis-triazolyl-pyridines are able to strip all actinides in all the different oxidation states from a diglycolamide-containing kerosene solution into an acidic aqueous phase. The ascertained high actinide selectivity, efficiency, extraction kinetics, and chemical/radiolytic stability spotlight this hydrophilic class of ligands as exceptional candidates for advanced separation processes fundamental for closing the nuclear fuel cycle and solving the environmental issues related to the management of existing nuclear waste.

Time-Resolved Laser Fluorescence Spectroscopy Study of the Coordination Chemistry of a Hydrophilic CHON [1,2,3-Triazol-4-yl]pyridine Ligand with Cm(III) and Eu(III)

“…PTD was synthesized at the University of Parma. 32 The ligand stock solutions for titration experiments were prepared by dissolving 13.16 mg of PTD in 500 L of the respective medium (10 -3 mol/L HClO 4 or 0.44 mol/L HNO 3 ) yielding a PTD concentration of 80 mmol/L. All solutions were prepared with ultrapure water (Millipore, Billerica, USA; 18.2 MΩ•cm).…”

“…Recently, a new CHON water-soluble ligand, 2,6-bis[1-(propan-1-ol)-1,2,3-triazol-4-yl]pyridine (PTD, Figure 2), was developed. 32 Similar to SO 3 -Ph-BT(B)P, PTD efficiently strips actinide ions, however with a slightly lower selectivity. Furthermore, PTD is satisfactorily stable towards radiolysis to allow for an application under conditions encountered in solvent extraction processes for actinide recycling.…”

“…Furthermore, PTD is satisfactorily stable towards radiolysis to allow for an application under conditions encountered in solvent extraction processes for actinide recycling. 32…”

Selective Extraction of Americium(III) over Europium(III) Ions with Pyridylpyrazole Ligands: Structure–Property Relationships

“…Kiefer et al examined the complexation behaviors of 2,6‐bis[1‐( p ‐tolyl)‐1 H ‐1,2,3‐triazol‐4‐yl]pyridine (BTTP) with Eu III , Sm III , and Cm III ions through single‐crystal X‐ray diffraction and time‐resolved laser fluorescence spectroscopy (TRLFS) . Afterwards, Macerata et al found that hydrophilic clicked 2,6‐bis(triazolyl)pyridines could selectively strip the actinides from a diglycolamide‐containing kerosene solution into an acidic aqueous phase . These findings provided new information about the relationship between molecular structure and extraction for An III /Ln III separation.…”

Do An(iii) and Ln(iii) ions form heteroleptic complexes with diglycolamide and hydrophilic BT(B)P ligands in solvent extraction systems? A spectroscopic and DFT study

“…While this study is the first to support the existence of heteroleptic complexes in solvent extraction systems combining heterocyclic N-donor ligands and TODGA, its results may be of more general relevance: for example, in the case of another water-soluble N-donor ligand, 2,6-bis(1H-1,2,3-triazol-4-yl) pyridine, similar discrepancies between the results of solvent extraction 47 and spectroscopic studies 48 were observed.…”