Jobs offers

1. Hydration forces and ionic specificity in silica surfaces Thesis supervisor: J.-F. Dufrêche

We propose to study by modelling the origin of hydration forces between silica surfaces, and their link with the specific adsorption of ions. This theoretical work will be based on a multi-scale approach. The idea consist in understanding the origin of surface phenomena who couple electrostatic force and hydration. This work is all the more significant since these phenomena drive many of the numerous applications of silicas, i.e. in separation chemistry as a nanoporous material.
More precisely, an atomic model of silica, depending on the pH and of the ions in solution will be proposed. Molecular dynamics and Monte Carlo simulations will allow the deduction of a coarse-grained model, which will be solved by density functional theory.

Together with dynamical (electrokinetic phenomena) and equilibirum (ion exchange) experiments performed in ICSM, we will determine how the various ions modify the surface and drive the behaviour and the one of the solvent. In a longer term, it should be possible to propose a theory which is quantitatively in agreement with experiments, and which takes into account molecular effects.

2. Multiscale modelling for separation chemistry: aggregates in organic phase for separation chemistry Thesis supervisor: J.-F. Dufrêche

Separation processes performed for recycling of heavy metals commonly use liquid-liquid extraction for which ions are selectively transferred from an aqueous to an organized organic phase. The description of the aqueous phase is being relatively well established, but for the organic phase nothing exists from a predictive point of view. This thesis will study the physical chemistry of liquid-liquid extraction from a theoretical approach. The main goal is the understanding of the various effects (solvation, electrostatic and Van der Waals forces, entropy), which drive the transfer from one aqueous phase to an organic organized phase. A method based on density functional theory (classical DFT) will allow the calculation of the ion distribution in the various inverse micelles. Then the various thermodynamical properties of the system will be obtained. The experimental support will be first the extraction of Europium nitrate thanks to DMDOHEMA for which experimental data have been measured. Molecular modelling will allow the checking of this mesoscopic approach and it will provide some physical parameters, specially for the solvation effects.