Inhibition of mineral dissolution by aggregation of colloidal particles driven by diffusiophoresis

This letter presents a new mechanism of interaction between mineral dissolution and colloidal transport. Using microfluidic experiments, we demonstrate that diffusiophoresis, i.e., the motion of colloidal particles due to solute concentration gradients, offers an appealing solution to drive colloidal particles toward a dissolving mineral. We report that particle aggregation limits the mineral dissolution through the formation of a passivation layer around the mineral. This work could be exploited to turn undesirable mechanisms (e.g., dissolution of confinement barriers and release of toxic components by contaminants trapped in porous formations) into positive feedback as the concentration gradients resulting from these events become the driving force to deliver colloids for remediation.