Separation of rare earth compounds from water into an organic phase in practical cases requires the use of specific ion binding ligands in high concentrations, that form a blocking layer above an ion concentration threshold, experimentally characterized.
These tend to form complex liquid crystalline phases preferentially at ion-rich locations inside a pertraction membrane. They form a blocking layer above an ion concentration threshold, which is experimentally characterized. It is shown to limit the flux through the membrane in a pertraction system. This feedback leads to a stationary membrane permeation rate that can be modeled-without any free parameters in very good agreement with experiment.