title: MRI evidence for a receding-front effect in drying porous media.
abstract: After drying colloidal particles suspended in a porous medium a concentration gradient appears. Using ^{1}H MRI we propose a protocol to observe simultaneously the distributions of air, liquid, and colloid through the unsaturated solid porous structure. Thus we show that the above phenomenon comes from a receding-front effect: The elements migrate towards the free surface of the sample and accumulate in the remaining liquid films. Our understanding of the process makes it possible to establish a simple model without diffusion predicting the drying rate and the concentration distribution in time, in excellent agreement with the experimental observations.
authors.affiliation: Université Paris-Est, Laboratoire Navier (UMR8205), ENPC-IFSTTAR-CNRS, 2 Allée Kepler, Champs sur Marne, France. emmanuel.k@gmail.com
authors.forename: E
authors.initials: E
authors.lastname: Keita
authors.forename: P
authors.initials: P
authors.lastname: Faure
authors.forename: S
authors.initials: S
authors.lastname: Rodts
authors.forename: P
authors.initials: P
authors.lastname: Coussot
mesh_terms: D000327:Adsorption; D000388:Air / Q000032:analysis*; D003198:Computer Simulation; D003890:Desiccation / Q000379:methods*; D004058:Diffusion; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D016062:Porosity; D011522:Protons; D012996:Solutions / Q000737:chemistry*
chemical_list: D011522:Protons; D012996:Solutions