Sequestration of Actinides by an Extraction Chromatography Resin Containing a Triaza-9-crown‑3 Functionalized Diglycolamide

We prepared a new extraction chromatography resin by coating a diglycolamide (DGA) ligand having three DGA moieties tethered to a triaza-9-crown-3 scaffold (TAM-3-DGA) on an inert solid support. This resin was evaluated for the separation of actinides and lanthanides from moderate acid solutions of 0.01–6 M HNO3. The distribution coefficient (K d) values for trivalent and tetravalent actinides (Am3+, Np4+, and Pu4+) on the resin were large enough (>1 × 104 mL/g) between 2 and 6 M HNO3 for its real application in separating these minor actinides. The metal ion sorption mechanism studied for Eu3+ and Pu4+ indicated the existence of a chemisorption phenomenon. The sorption energies for Eu3+ and Pu4+ were 12.1 ± 0.72 and 18.5 ± 0.5 kJ/mol, respectively. The resin capacity was 13.9 ± 0.3 mg of Eu3+ and 11.7 ± 0.4 mg of Pu4+ per g of the resin, corresponding to the formation of a 1:1 metal/ligand complex for the Eu3+ ion and a 1:2 metal/ligand complex for the Pu4+ ion. The sorbed Eu3+ and Pu4+ ions from the resin phase were effectively eluted with complexing reagents like HEDTA and oxalic acid, respectively. The column capacity was ∼80% of the batch equilibrium value for both Eu3+ and Pu4+ ions.