Complexation and Solvent Extraction Studies of High Valency Actinides by Hard/Soft Donor Schiff Base Ligands

摘要

Successful separation of the mid actinides (U, Np, Pu, Am) from other elements is imperative for drastically lowering the long term radiotoxicity of SNF. Ubiquitous to these mid actinides is a wide range of oxidation states (+Ⅲ, +Ⅳ, +Ⅴ, +Ⅵ) where the +Ⅴ and +Ⅵ oxidation states exist in a linear dioxo actinyl cation AnO_2~(n+) (O=An=O)~(n+) guaranteeing unique ligand coordination about the equatorial plane. Multidentate Schiff base ligands which possess nitrogen and oxygen donor groups can accommodate the steric demands of the actinyl cations as well as providing selectivity for actinides in a separation process. Group extraction or retention of the mid actinides in a biphasic solvent extraction process can be achieved by complexation of their actinyl species by Schiff base ligands in one phase while all other non actinyl cations are complexed in the other phase.