Séminaire Théorie

Mardi 12 Avril 2016 à 11h00.

Transport in hydrated clays at the nanoscale : simulations and experiments

''Clays are porous lamellar materials. Their wide use in industrial applications, energy and environmental engineering (oil recovery, ground water remediation, geological barrier for radioactive waste and CO2) is partly due to their remarkable properties of retention at the mineral surface. In environmental engineering, the role of water on clay permeability and their retention properties is crucial. Indeed, the water is the vector of the motion of the species present in the medium, including for instance the hazardous elements. Clays can show different behaviors towards water, depending in particular on the value of the negative structural charge carried by the mineral layers and the relative interactions between water, cations and clay surfaces. Provided that the interatomic interactions are properly defined, classical molecular simulations can help to better understand what happens at the clay/water interface because they allow a detailed picture of the structure, thermodynamics and dynamics of the system. The first part of my talk will be dedicated to the dynamical properties of water in clays obtained by classical molecular dynamics and quasi-elastic neutron scattering. I will show how the comparison between both is crucial in order to interprete experiments on the one hand and to test the validity of simulations parameters (force-field) on the other hand. In a second part, I will indeed explain how to improve the existing classical force-fields by including atomic polarisability.''