Influence of Ionic Strength and Flow Rate on Silt Particle Deposition and Release in Saturated Porous Medium: Experiment and Modeling

In this paper, the influence of ionic strength on the dynamic transport of silt microparticles through saturated sand texture is studied in the presence of repulsive interactions. The deposition and release phenomenon is investigated through experimental column trials. Different ionic strengths are applied by adjustment of suspension salinity. Two trial configurations are performed: Monotonic experiments highlight particle deposition mechanisms, and non-monotonic tests focus on release phenomena under ionic strength and flow rate perturbations. Through this experimental study, the ionic strength influence on the deposition and release phenomenon is shown. The presence of both mechanical and physico-chemical mechanisms is proved experimentally. This study proves that ionic strength variation is a primal parameter which predicts the attachment and detachment of particles at constant flow. These experiments are simulated and reproduced through a numerical model based on original deposit and release kinetics which are proposed in this study. This model is the coupling of two multiphasic problems describing conservative salt and microparticle transport. The proposed kinetics formulations are founded on performed experimental test constitutions in this study. They take into account the flow rate and the suspension ionic strength. The suggested model reproduces well the experimental description of the suspended particles transport under the influence of ionic strength and flow velocity variations. It permits to predict the deposition and release phenomenon.