Extraction/removal of uranium, U(VI) from chloride solutions by an environment-friendly extractant

Abstract

The extraction/removal of uranium U(VI) from chloride solutions have been investigated in the pH region by using N, N-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA, HA) as an environment-friendly extractant. The influence of acid concentration in the aqueous phase, the ligand concentration in the organic phase, and the temperature on the extraction of U(VI) have been studied. The results from slope analysis methods reveal that the extraction of uranium is strongly pH-dependent and directed by cation-exchange mechanism. The proposed composition of the extracted complex species is UO2A2·HA with a core UO2A2 and one protonated ligand molecule binding to the second coordination sphere of the metal ion via hydrogen bonding. The extraction thermodynamic data demonstrate an exothermic reaction. The considerably high extraction affinity for uranium makes the HDEHDGA/kerosene system a promising candidate for the purification of water solutions from radioactive pollutants.