Highly Efficient Europium(III) Uptake with an Extraction Chromatographic Resin Containing a Unique Multiple Diglycolamide Ligand with a Tetraaza-12-crown-4 Scaffold

An extraction chromatographic resin was prepared by impregnating Chromosorb-W with a unique ligand consisting of four diglycolamide moieties functionalized to a tetraaza-12-crown-4 scaffold. This resin was evaluated for the uptake of Eu3+, as a representative of trivalent lanthanides and actinides, from moderate acid solutions. The distribution coefficient of Eu3+ on the resin was very large (>1 × 104) in the acid range 0.1–6 M HNO3, and its sorption followed the pseudo-second-order kinetic model. The sorption of Eu3+ proceeded via a chemisorption phenomenon with a sorption energy of 26 ± 2 kJ/mol. The Eu3+ sorption onto the resin was both enthalpy and entropy driven. FTIR and fluorescence measurements of the Eu3+ complex formed on the resin confirmed the chemical interaction between the Eu3+ and the ligand present on the solid support. The resin capacity was 14.4 ± 0.1 mg of Eu3+ per g of resin corresponding to the formation of a 1:1 metal/ligand complex. The sorbed Eu3+ from the resin could be efficiently desorbed with 0.1 M HEDTA (N-(2-hydroxyethyl)ethylenediamine triacetic acid). The column loading of Eu3+ was 83% of the equilibrium value with a narrow elution profile. The hydrolytic and leach stability of the impregnated resin was excellent, tested in five successive cycles of loading and elution.