Issue 6, 2023

Diffusiophoresis of a spherical particle in porous media

Abstract

Recent experiments by Doan et al. (Nano Lett., 2021, 21, 7625–7630) demonstrated and measured colloid diffusiophoresis in porous media but existing theories cannot predict the observed colloid motion. Here, using regular perturbation method, we develop a mathematical model that can predict the diffusiophoretic motion of a charged colloidal particle driven by a binary monovalent electrolyte concentration gradient in a porous medium. The porous medium is modeled as a Brinkman medium with a constant Darcy permeability. The linearized Poisson–Boltzmann equation is employed to model the equilibrium electric potential distribution that is driven out-of-equilibrium under diffusiophoresis. We report three key findings. First, we demonstrate that colloid diffusiophoresis could be drastically hindered in a porous medium due to the additional hydrodynamic drag compared to diffusiophoresis in a free electrolyte solution. Second, we show that the variation of the diffusiophoretic motion with respect to a change in the electrolyte concentration in a porous medium could be qualitatively different from that in a free electrolyte solution. Third, our results match quantitatively with experimental measurements, highlighting the predictive power of the present model. The mathematical model developed here could be employed to design diffusiophoretic colloid transport in porous media, which are central to applications such as nanoparticle drug delivery and enhanced oil recovery.

Graphical abstract: Diffusiophoresis of a spherical particle in porous media

Article information

Article type
Paper
Submitted
09 des. 2022
Accepted
15 jan. 2023
First published
17 jan. 2023

Soft Matter, 2023,19, 1131-1143

Diffusiophoresis of a spherical particle in porous media

S. Sambamoorthy and H. C. W. Chu, Soft Matter, 2023, 19, 1131 DOI: 10.1039/D2SM01620F

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