Excellent Selectivity for Actinides with a Tetradentate 2,9-Diamide-1,10-Phenanthroline Ligand in Highly Acidic Solution: A Hard–Soft Donor Combined Strategy

Abstract

In this work, we reported a phenanthroline-based tetradentate ligand with hard-soft donors combined in the same molecule, N,N'-diethyl-N,N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen), for the group separation of actinides over lanthanides. The synthesis and solvent extraction as well as complexation behaviors of the ligand with actinides and lanthanides are studied experimentally and theoretically. The ligand exhibits excellent extraction ability and high selectivity toward hexavalent, tetravalent, and trivalent actinides over lanthanides in highly acidic solution. The chemical stoichiometry of Th(IV) and U(VI) complexes with Et-Tol-DAPhen is determined to be 1:1 using X-ray crystallography. The stability constants of some typical actinide and lanthanide complexes of Et-Tol-DAPhen are also determined in methanol by UV-vis spectrometry. Density functional theory (DFT) calculations reveal that the An-N bonds of the Et-Tol-DAPhen complexes have more covalent characters than the corresponding Eu-N bonds, which may in turn lead to the selectivity of Et-Tol-DAPhen toward actinides. This ligand possesses merits of both alkylamide and 2,9-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-1,10-phenanthroline (R-BTPhen) extractants for efficient actinide extraction and the selectivity toward minor actinides over lanthanides and hence renders huge potential opportunities in high-level liquid waste (HLLW) partitioning.

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

“…The peak at λ = 252 nm decreases gradually, and the appearance of a new peak at λ = 290 nm suggests that a metal–ligand complex is formed. Moreover, two isosbestic points are present in the spectra; therefore only one metal–ligand complex is present in the solution , …”

Synthesis, Structures, and Luminescent Properties of Lanthanide Complexes with Triphenylphospine Oxide

“…In recent years interest in complexes containing lanthanide triflates or chlorides arises because of their varied structures, coordination mode, physicochemical, biochemical, and medical applications as well as luminescent properties, and function as catalysts for organic reactions , . Facts prove that PO‐based ligands are widely used in f‐element chemistry for coordinating to lanthanide metal ions due to their strong coordination abilities and attractive luminescent properties .…”

Application of graphene oxides and graphene oxide-based nanomaterials in radionuclide removal from aqueous solutions

“…Different kinds of techniques such as sorption, (co)precipitation, ion exchange, solidification, and membrane separation, have been extensively applied to eliminate radionuclides from wastewater [3,4]. Among these methods, sorption technique has widely been applied in large scale and in real environmental pollution management because of its simple operation, low cost and applications in large scale [5][6][7][8]. The application of sorption technique in the removal of radionuclides from large volumes of aqueous solutions has been studied extensively by using batch techniques, and the interaction mechanisms were discussed from the results of surface complexation modeling, spectroscopic analysis and theoretical calculations.…”