Effect of long-range electrostatic repulsion on pore clogging during microfiltration.

We perform computer simulations based on adhesive contact mechanics to demonstrate the clogging process of charged microparticles at the single-pore level. The effect of long-range Coulomb repulsion on clogging is characterized in terms of bulk permeability, the number of penetrating particles, and particle capture efficiency. Results indicate that the repulsion among particles delays or even totally prevents the formation of clogs. A clogging phase diagram, in the form of the driving pressure and a proposed charge parameter κ_{q}, is constructed to quantify the clogging-nonclogging transition. In addition, a critical state, where the capture efficiency of particles decreases to its minimum, is identified as a clogging-nonclogging criterion for repulsive particles. The distributions of the local volume fraction show that the structure of clogs is mainly determined by short-range adhesion. With relatively strong adhesion, a loose clog will be formed and it is easier for particles to penetrate. Finally, a schematic representation of the clogging process, considering both long-range repulsion and adhesion, is proposed to show the relationship between the clogging results and the interparticle interactions.