UC Irvine

The fission and neutron capture reaction occurring in nuclear reactors generates a waste stream which includes more than 40 elements across the periodic table. The chemical separation of metal ions by liquid-liquid extraction from an aqueous phase into an organic phase is an important technology for purifying, recycling or disposing of solutions from metallurgical or nuclear industry. In recent studies, the extraction of the metal ion into microemulsion containing an anionic surfactant and an electrically neutral organic ligand (extractant) has been introduced as a new technology.

In this study, we applied an anionic surfactant to understand better the mechanism of liquid-liquid extraction under microemulsion-forming conditions. Aerosol OT (AOT) is well used as an anionic surface-active agent to form a microemulsion but it is not used alone in extraction systems because of poor extractability, and poor selectivity for lanthanides in their extraction from aqueous nitric acid solutions. It is known that the separation of lanthanides is considerably improved by using the combination of AOT and neutral extractant such as CMPO or bulky diamide, but the mechanism of the extraction remains

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unclear. The aim of this research is to understand the extraction mechanism of an extraction system combining AOT and CMPO using various aqueous conditions and by analyzing the coordinate environment surrounding the extracted metal ion. A variety experimental technique including UV-vis-NIR, X-ray scattering and absorption spectroscopy, have been employed to gain a thorough understanding of the system. I will discuss the findings and their implementations on the extraction process of lanthanides from acidic environments.