Chemically functionalized diglycolamide resin for rapid and efficient recovery of Am(III) from nitric acid medium

A diglycolamide (DGA)-functionalized silica-based extraction chromatography resin was synthesized and evaluated for the separation of trivalent actinides from nitric acid medium. Batch sorption studies showed strong affinity of the resin toward Am³⁺, with distribution coefficients (K_d) exceeding 5000 mL/g above 3 M HNO₃. Sorption equilibrium was achieved within 20 min, indicating rapid uptake kinetics suitable for separation applications. Equilibrium sorption studies were performed using Eu³⁺ as a non-radioactive surrogate for Am³⁺. The resin exhibited a maximum Eu³⁺ uptake capacity of 9.5±0.5 mg/g. The equilibrium data were interpreted using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherm models. The Langmuir model provided the best agreement with the experimental data, confirming monolayer sorption on a homogeneous surface containing a finite number of active sites. The mean sorption energy obtained from the D-R model was found to be 15.9±0.7 kJ/mol, demonstrating that the uptake process proceeds mainly through chemical interaction, rather than physical sorption. Further mechanistic evaluation using a theoretical sorption kinetic model also confirmed the predominance of monolayer sorption for Am³⁺. The developed DGA-grafted silica resin shows promise for efficient recovery of minor actinides from acidic radioactive waste streams.