Seminar of Dr Michael J. SERVIS (Argonne National Laboratory, Lemont, IL, USA)

Recovery and recycling of critical materials through solution-phase separations enables a wide range of important technologies. Deeply inspired by work performed at ICSM, we investigate the relationships between structure and phase transitions (i.e., third phase formation) in malonamide-based organic phases with application to lanthanide separations. We combine molecular dynamics simulations with experimental small angle x-ray scattering and x-ray photon correlation spectroscopy to explore how solution structure depends on temperature, extractant concentration, and the presence and composition of extracted aqueous solutes. Overall, we find composition fluctuations resulting from the incipient phase transition can dominate solution mesostructure under a large range of conditions, providing an explicit connection between mesoscopic ordering of the liquid and its phase behavior. By connecting x-ray scattering measurements of composition fluctuations with molecular simulation and thermodynamic modeling, we aim to create a comprehensive picture of solution behavior, including prediction of liquid-liquid phase diagrams.