Seminar Pauline Etienne

Soil and groundwater remediation is a major challenge. A promising approach relies on diffusiophoresis, i.e., the motion of colloids induced by solute concentration gradients generated by contaminants.
This mechanism could enable particles to access otherwise poorly connected regions of the porous medium, such as dead-end pores. However, it remains largely overlooked in conventional transport models and has been scarcely investigated in heterogeneous geometries.

This study aims to improve the understanding of this phenomenon using microfluidic devices that replicate natural sandstone-like structures.
These systems allow high-resolution observation of particle trajectories at the pore scale. Experiments are conducted with and without a controlled salt gradient, visualized using a dye with similar transport behavior. This approach isolates the specific effect of diffusiophoresis on micron-sized polystyrene particles.

The results show that chemical gradients influence particle behavior by modifying their mobility and trajectories. The role of pore structure is also highlighted. These findings demonstrate the importance of
diffusiophoresis in colloid transport within heterogeneous porous media.