Synthesis and characterization of N,N,N′,N′-tetraalkyl-4-oxaheptanediamide as extractant for extraction of uranium(VI) and thorium(IV) ions from nitric acid solution

Abstract

Tridentate ligand N,N,N′,N′-tetraoctyl-4-oxaheptanediamide(TOOHA) and other three analogous diamides have been prepared and characterized by using NMR spectra and element analysis. The extraction of UO2 2+ and Th4+ with the present extractants was investigated at 293 ± 1 K from nitric acid solutions. n-Octane was found to be the most suitable diluent in the present study compared with other diluents tested. Extraction distribution ratios (D) of U(VI) and Th(IV) have been studied as a function of aqueous concentrations of HNO3, extractant concentrations. The results indicated that U(VI) is mainly extracted as UO2(NO3)2·2TOOHA. In the case of Th4+ ion, the possible compositions of extracted species in organic phase were presumed to be Th(NO3)4·2TOOHA and Th(NO3)4·3TOOHA. In addition, the influence of concentration of sodium nitrate as salting-out agent on the distribution ratio of U(VI) and Th(IV) with TOOHA was also evaluated.