M. Duvail

Collaborations: Pr. Th. Zemb (ICSM/LTSM), Pr. L. Arleth (University of Copenhagen, Danemark), Dr. S. Marcelja (Australian National University, Canberra) 

The mesoscopic modelling of the microemulsion (water / oil / surfactant) thermodynamics properties is crucial to understand the phenomena occuring during the liquid-liquid extraction process (mainly used for the ions separation).
The mains objectives of this study are :

• the description and prediction of the microemulsion microstructures,
• bridging the microscopic properties of such solutions (at the molecular scale) and the macroscopic ones.

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Collaborations: Dr. Ph. Guilbaud (CEA), Pr. J.-F. Dufrêche (ICSM), Pr. M. Jardat (PHENIX, Sorbonne Université)

Multiscale modeling approaches are developed and implemented to determine the thermodynamic properties of ions in solution, including lanthanide (Ln³⁺) and uranyl (UO₂²⁺) salts. These approaches couple classical molecular dynamics simulations with explicit polarization and "coarse-grained" simulations. For example, by calculating the mean force potentials, we analyze the association/dissociation processes of the complexes formed in solution.
We also access the activity coefficients of electrolytes in solution, directly comparable to experiments, by molecular modeling of osmotic equilibrium.

Molecular dynamics simulations of lanthanoid in organic phases (alcohol and alkane) are performed to understand the solvation properties of such cations. We also focus on the thermodynamics properties of micelles composed of ions, water and extractant molecules in apolar solvents (such as alkanes), and especially their curvature free energies. These simulations pave the way for further structural studies in organic solvents: anion coordination, association / complexation with ligands (monoamide, diamide, nitrogen ligands, ...), and therefore may improve the understanding of ion speciation in organic phases.

Collaborations: Dr. S. Dourdain (ICSM/LTSM), S. Pellet-Rostaing (ICSM/LTSM), Dr. S. Le Crom (ICSM/LMCT)

Projet : Lab'UM Chimie (University of Montpellier) RAMELI

The objective of the RAMELI project (Molecular dynamics to rationalize structural effects on extraction mechanisms in Ionic Liquid) is to study and compare the effect of ionic liquids structure on the supramolecular aggregation of extraction phases and to put them in relation with their extraction properties. This project is based on results obtained from studies performed at ICSM in an attempt of developing extraction processes in ionic liquids, which demonstrated that the best extraction performances in ionic liquid media are not only due to different complexation mechanisms, but also to different structural properties.

Since no experimental approach has so far been able to fully describe the structural organization of the extraction phases in ionic liquid, the project aims at rationalizing all the experimental results by simulating these phases by molecular dynamics. By allowing the definition of proper adjustment models for the previously acquired data, this theoretical approach will make possible to describe the multiscale structure of these phases (complexes, aggregates, structure of the ionic liquid) and will thus provide new elements of understanding on the impact of structural effects on extraction performance.

Collaborations: Dr. A. Poulesquen (CEA), Dr. D. Petit (L2C, University Montpellier), J. Lind (Woellner GmbH & Co.KG, Germany)

Projet : ANR DYNAMISTE ANR-15-CE07-0013

DYNAMISTE (Dynamics of Alumino-Silicates Fluids) aims at developing experimental and theoretical tools in order to optimize industrial processes in which alkali solutions of aluminosilicates are involved in an attempt of developing sustainable and clean industry. This project gathers the expertise of ICSM, a CEA department for the waste retreatment and conditioning and specialist for the characterization and formulation of cement-based materials, and a CNRS team at the Laboratoire Charles Coulomb expert in multi-scale NMR technics, in collaboration with the German industrial partner Wo?llner GmbH & Co.KG, who is one of the leaders in production of alkali silicate solutions.

This project relies on a synergic approach coupling both experiments and modeling. In order to access all the spatio-temporal phenomena of such systems, the experimental part consists in studies based on (i) rheology techniques coupled with scattering techniques: Dynamic light scattering (DLS), small and wide angle x-ray and (or) neutron scattering and diffraction (SWAXS, SANS and XRD), and on (ii) multi-scale NMRapproaches (from Å to few tens μm). In the meantime, the theoretical part is based on multi-scale methods coupling molecular dynamics and coarse-grained simulations, allowing for accessing the structural and dynamical properties of these fluids at both the molecular and supramolecular scales.