(171i) Elucidating Hydrodynamic Interactions and Steric Hindrance in Diffusiophoresis in Porous Media

Diffusiophoresis is the deterministic colloidal motion induced by a solute concentration gradient. Existing theories focus on diffusiophoresis in a free electrolyte solution but a predictive model for diffusiophoresis in porous media is lacking. In this work, we develop a predictive model for diffusiophoresis in porous media saturated with electrolytes, accounting for both the hydrodynamic interactions and steric hindrance. First, we present a micromechanical model that accounts for hydrodynamic interactions in diffusiophoresis in porous media. Second, we present the results from particle dynamics simulations that account for steric hindrance in diffusiophoresis in porous media. Third, we present the use of statistical mechanics theories to combine the result from the micromechanical model and particle dynamics simulations to furnish the predictive model for diffusiophoresis in porous media. The model predictions show excellent agreement with experiments. The predictive model developed here can be employed to tailor diffusiophoretic transport in porous media, which are central to applications such as nanoparticle drug delivery and enhanced oil recovery.