Colloidal dynamics in a non-transparent soil-like matrix

The physical understanding of colloidal transport within liquid-saturated porous media is a prerequisite in many environmental and industrial fields. We wish to use XPCS to study colloidal transport in 3D in a non-transparent mineral-based confining matrix filled with water. This presents several advantages over optical studies of colloidal transport, which rely on optically transparent samples, a 2D geometry and optical matching of the filling fluid. We build upon our knowledge of aqueous clay suspensions and gels to provide a “soil-like” confining matrix, which presents a local planar confinement (platelets separated by the order of 10 to 100 nm) in an overall isotropic sample. In such matrix, we shall study diffusion of 30nm Au nanoparticles. We expect to extract (a) effective diffusion coefficents of Au colloids as a function of platelet separation and size (b) the detailed shape of the time-dependent scattering function for future development of diffusion models in such media.