Extraction of U(VI) and Th(IV) ions from nitric acid solutions with N,N,N′,N′-tetra-2-ethylhexylglutaramide

Abstract

N,N,N′,N′-Tetra-2-ethylhexylglutaramide (TEHGA) was used as a new extractant for the extraction of U(VI) and Th(IV) from nitric acid solutions. Toluene was found to be the most suitable diluent for TEHGA. The extraction of nitric acid was also studied. The influence exerted on the distribution ratio (D) of U(VI) and Th(IV) by the concentrations of HNO₃, TEHGA, and LiNO₃ as salting-out agent, and also by the equilibration time, temperature, and kind of diluent was examined. Good U–Th separation can be achieved using 2–3 M HNO₃. The results obtained show that U(VI) and Th(IV) are mainly extracted as UO₂(NO₃)₂·2TEHGA and Th(NO₃)₄·TEHGA, respectively. The IR spectra of the extracted species were analyzed. The thermodynamic functions of the process were calculated. Back-extraction of U(VI) and Th(IV) from the organic phases was also studied.