•A new solvent system for highly selective UO22+ extraction was developed.•The new system provides a highly efficient extraction of UO22+ from HNO3 media.•The new system shows good practical feasibility by cycling organic phase.•The new system is potentially to be applied in group separation of An over Ln.A novel tetradentate ligand combining hard O-donor and soft N-donors in the same molecule, N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen), was developed in our laboratory aiming at the group separation of actinides from lanthanides. Herein, the solvent extraction of UO22+ by Et-Tol-DAPhen in 1-(trifluoromethyl)-3-nitrobenzene diluent was investigated in detail. The effects of contact time, Et-Tol-DAPhen concentration, acidity, and competing ions on the extraction were discussed, the extracted UO22+ speciation was analysed, and the stripping of UO22+ from organic phase was performed. The results clearly show that Et-Tol-DAPhen/1-(trifluoromethyl)-3-nitrobenzene provides a highly efficient extraction of UO22+ from HNO3 media with a fast extraction kinetics of less than 5 min and a large distribution ratio of more than 300. Moreover, the system shows excellent selectivity toward UO22+ over Ln3+ in a wide acidity range. Stripping experiments indicate that almost a complete back extraction of UO22+ could be achieved via only one stage operation using 5% Na2CO3 solution. Findings of the present work provide new data for assessing the feasibility of Et-Tol-DAPhen, as well as other new ligand with hard–soft donors combined in the same molecule, applied in the group separation of actinides over lanthanides.

Functionalized magnetic Fe3O4@SiO2 composite nanoparticles were prepared by simply embedding iron oxide nanoparticles into MCM-41 through one-step synthesis process, followed by aminopropyls grafting on the mesopore channels, aiming to efficiently and conveniently uptake U(VI) from aqueous solution. The resultant material possesses highly ordered mesoporous structure with large surface area, uniform pore size, excellent thermal stability, quick magnetic response, and desirable acids resistance, confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption/ desorption experiments, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Detailed U(VI) sorption test indicated that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of 160 mg/g at pH 5.0±0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The absorbed U(VI) can be easily desorbed by 0.01 mol/L or more concentrated HNO3 solution, and the reclaimed sorbent can be reused with no obvious decrease of sorption capacity even after 4 sorption-desorption cycles. The present results suggest the vast opportunities of this kind of magnetic composite on the solid-phase extraction of U(VI).

A dihydroimidazole functionalized magnetic mesoporous silica with core–shell structure was fabricated, aiming to convenient remove U(VI) from aqueous solution. The batch sorption tests revealed that this material is indeed an effective U(VI) sorbent with fast sorption kinetics of less than 2 h, large sorption capacity of more than 100 mg/g at pH 5.5 ± 0.1, and desirable selectivity towards U(VI) ions over a range of competing metal ions. The sorbent can be readily separated from solution by simply adding an external magnetic field.

The selective extraction of minor actinides(III) from the lanthanides(III) is a key step for spent fuel reprocessing. Theoretical calculations of geometries, electronic structures, coordination complexion, and thermodynamic properties of the actinides are essential for understanding the separation mechanisms and relevant reactions. This article presents a critical review of theoretical studies on actinide systems involved in the An(III)/Ln(III) separation process. We summarize various theoretical methods for electronic and molecular scale modeling and simulations of actinide coordination systems. The complexing mechanisms between metal cations and organic ligands and the strategies for the design of novel ligands for separation are discussed as well.Highlights► We review recent advances in computational modeling and simulations on the An(III)/Ln(III) separation process. ► Various theoretical methods for electronic and molecular-scale modeling and simulations of actinide systems are summarized. ► The complexation between soft-donating ligands and An(III)/Ln(III) ions are explored. ► The strategies for design of novel organic ligands for separation are discussed.