Résumé
Recycling of metals, such as rare earths, lanthanides or actinides, into valuable material relies on ion specific separation, basis of the hydrometallurgy. Most of efficient methods known for separating ions are based on equilibria between complex fluids, i.e. water in oil (w/o) microemulsions. In the diluted regime, w/o reverse micelles, that selectively up-take some ions, are generally considered as spheres containing extractant molecules, water molecules, and complexed ions. However, in industrially relevant cases of liquid – liquid extraction, it is known that extractant aggregates cannot be described as simple metal-ion complexes spherical on average, since the high conductivity observed in the oil phase proves a bicontinuity degree of the system.Examples of nonionic w/o microemulsions have been simulated using the wavelet method developed by Arleth and Marčelja [1]. The thermodynamics of the interface is based on the Helfrich formalism [2]. In our model, the Helfrich free energy is minimized as a function of the bending and Gaussian elastic constants, which refer to the rigidity of the surfactant film in term of energies, and the spontaneous curvature of the surfactant film, which corresponds to its preferred curvature [3].Influence of the bending and Gaussian elastic constants is observed on frustrated and unfrustrated microemulsion structures, their scattering properties, and predicted ternary phase diagrams.However, it is well known that efficient surfactants used for such processes are mainly ionic. Therefore, it is crucial to develop a more realistic model that takes into account (i) the ionic character of the surfactant, and (ii) the presence of cations in solutions. Taking into account, in a same model, both the metal complexation and the colloidal terms [4], will provide predictive modelling of ion separation.References[1] L. Arleth, S. Marčelja and Th. Zemb, J. Chem. Phys., 115, 3923 – 3936 (2001)[2] W. Helfrich, Z. Naturforsch. C, 28, 693 – 703 (1973)[3] M. Duvail, L. Arleth, J.-F. Dufrêche and Th. Zemb, Phys. Chem. Chem. Phys., 15, 7133 – 7143 (2013)[4] Th. Zemb, M. Duvail and J.-F. Dufrêche, Isr. J. Chem., 53, 108 – 112 (2013)