Inner and outer sphere plutonium(Ⅳ) coordination with amide and carbamide ligands

摘要

A thorough characterization of actinide coordinationchemistry in organic solution is of particular interest in thedevelopment of effective solvent extraction separations forwaste remediation in advanced nuclear fuel cycles. This isall the more important for plutonium(Ⅳ) extraction thatPu(Ⅳ) exhibits a large diversity of coordination structuresin organic solution.In the present work, we have combined spectroscopic andcomputational methods to elucidate the structures ofplutonium(Ⅳ) ions with dialkyl monoamide and tetraalkylcarbamideligands in the solid state and in solution.Monoamides are the most serious alternative candidates toreplace tri-n-butyl phosphate (TBP) to achieve uranium(VI)and plutonium(Ⅳ) separation and they have receivedincreasing attention. It has been shown that slightlyaltering ligand’s structure or experimental conditions inducelarge variations of Pu(Ⅳ) extraction properties whileuranium(Ⅳ) extraction is much less impacted. In order tobetter understand the key contributions that governplutonium extraction efficiency, Pu(Ⅳ) coordinationstructures with monoamide and carbamide ligands havebeen investigated by varying the extractant structures (sizeand branching of alkyls chains, amide versus carbamide)and experimental conditions (nitric acid or extractantconcentrations).