(586g) Steric Hindrance in Diffusiophoresis in Porous Media

Diffusiophoresis refers to the deterministic colloidal motion induced by a solute concentration gradient. Diffusiophoresis in porous media is distinct from diffusiophoresis in a free electrolyte solution in that the colloid experiences different hydrodynamic interactions and an additional steric hindrance. In this work, based on statistical mechanics theories we develop a predictive model for diffusiophoresis in porous media saturated with electrolytes, accounting for both the hydrodynamic interactions and steric hindrance. We report two key findings. First, we show that the predictions by our prior model that solely accounts for hydrodynamic interactions agree with experiments, but such agreement is lost when the colloid size and the pore size of the porous media become comparable. Second, we show that our present model that incorporates steric hindrance to our prior model gives accurate predictions to experiments, including the regime where the prior model underperforms. 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.