Uranium extraction by a bifunctional extractant dialkyl (2-(hydroxyamino)-2-oxoethyl) phosphonate

In this paper, a novel bifunctional molecule dialkyl (2-(hydroxyamino)-2-oxoethyl) phosphonate (DAHAOEP) containing both phosphoryl and hydroxamic groups was designed and synthesized, and used as a uranium extractant. The extraction properties of DAHAOEP were focused. Dihexyl (2-(hydroxyamino)-2-oxoethyl) phosphonate (DHHAOEP) was shown to have a better extraction effect on uranyl ions than dibutyl (2-(hydroxyamino)-2-oxoethyl) phosphonate (DBHAOEP) and diethyl (2-(hydroxyamino)-2-oxoethyl) phosphonate (DEHAOEP). Under the optimal extraction conditions, the extraction efficiency of DHHAOEP on uranyl ions could reach up to 98 %. Extraction saturation capacity, reusability and selectivity results indicated that the saturation capacity of DHHAOEP continuous extraction can reach 596 % after 10 times of extraction, DHHAOEP had been recycled more than 5 times, and exhibited a superior selectivity for uranyl ions. Slope method showed that DHHAOEP mainly coordinated with uranyl ions in a 1:2 coordination, i.e., monomolecular bidentate coordination M 2 L. FTIR and XPS analysis further confirmed that DHHAOEP combined with uranyl ions through it’s -C(=O)-NHOH and P = O groups to form a five-membered ring and P-O-U configuration, respectively.