ABSTRACT
The extractant-assisted transfer of metal ions between aqueous and organic phases underlies the industrial process of solvent extraction, which is important for separating, isolating, and thus purifying metal ions. X-ray studies of interfaces between immiscible liquids promise to reveal the mechanism of ion transport across the interface that occurs during solvent extraction. This chapter reviews advances that used interface-sensitive X-ray techniques to probe molecular ordering at the oil–water interface under conditions relevant to solvent extraction, as well as a recent pair of studies that combined X-ray and neutron reflectivity measurements. It discusses X-ray studies of liquid–liquid interfaces and liquid–vapor interfaces that investigated the molecular ordering and binding of ions and extractants. Neutron reflectivity shares many of the advantages with X-ray reflectivity in the investigation of molecular structures at liquid interfaces. Ion–extractant complexes can exhibit long-range ordering within the plane of the surface.
