Ion Extractant as Cosurfactant at the Water-Oil Interface in Microemulsions

Bicontinuous microemulsions are investigated as a model system for the specific adsorption phenomena of metal ions at the water-oil interface. Mixing an extremely hydrophobic ion extractant - tributyl phosphate (TBP) used here as co-surfactant with an extremely hydrophilic sugar-based surfactant, we describe a new type of functionalized microemulsions that shows the classical Winsor phases, by varying the surfactant/extractant ratio. We focus on the Winsor III-type microemulsions by determining the phase diagrams whereas the microstructures were accessed by performing small angle neutron scattering experiments. Ultimately, these microemulsions may pave the way for the design of new selective ion extraction processes.