Two extraction chromatography resins were prepared for the first time by impregnating multiple diglycolamide-functionalized ligands such as diglycolamide-calix[4]arene (C4DGA) and tripodal diglycolamide (T-DGA) on Chromosorb-W, an inert solid support, for the removal of hazardous actinides like Am(III) from radioactive waste solutions at 3M nitric acid. The resins were characterized by SEM, thermal and surface area (BET) analyses. The sorption of Am(III) on the two resins followed pseudo-second order sorption rate kinetics and was exothermic in nature. The sorption of trivalent f-elements proceeded through a chemisorption monolayer phenomenon as analyzed by using several isotherm models. The negative free energy change (ΔG) values of -34.46 and -28.45kJ/mol for T-DGA and C4DGA, respectively, indicate a chemical interaction between the metal ions and the ligands on the surface of the resins. Distribution coefficient measurements of various metal ions showed a selective sorption of trivalent f-elements over hexavalent uranyl ions and other fission product elements. Column studies on breakthrough indicated 0.76 and 0.37mg/g as the breakthrough capacities of the T-DGA and the C4DGA resins, respectively. It was possible to quantitatively elute the loaded metal ion using EDTA solutions.
Keywords: Actinides; Diglycolamides; Extraction chromatography; Separation; Sorption.
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