Mid-term thesis: Prediction of concentration gradients in geological porous media

The objective of this PhD is to predict the magnitude and location of local concentration gradients that develop in geological porous media due to mineral reactions. These concentration gradients can further lead to diffusiophoresis of charged particles, a phenomenon that is still not well understood in porous media. We will use microfluidic devices to study dissolution mechanisms of calcite crystals in controlled conditions We will assess the species transport dynamics in the vicinity of a dissolving crystal. Experimental results will extend the numerical models developed in our team that simulates the dissolution of solid minerals at the pore-scale. In a second step, more complex reactive micromodels will be considered, like flow-through reactors to localize concentration gradients generated by dissolution/precipitation. The experiments coupled with micro-Raman spectroscopic techniques will allow a quantitative in situ assessment of mineralogical changes in porous media during reactive transport processes. From Raman spectra we will obtain the mineral composition and solute composition, thus providing new insights into hydro-geochemical coupling in porous media.