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

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 UO 2 2+ and Th 4+ 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 HNO 3 , extractant concentrations. The results indicated that U(VI) is mainly extracted as UO 2 (NO 3 ) 2 ·2TOOHA. In the case of Th 4+ ion, the possible compositions of extracted species in organic phase were presumed to be Th(NO 3 ) 4 ·2TOOHA and Th(NO 3 ) 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.