Magnetophoresis of transition metal salts through porous media

Magnetomigration, or the movement of solutes in a solution driven by magnetic field gradients, presents a possible mechanism for emerging chemical process separations technologies, pollutant removal, and drug delivery; however, this phenomenon is still poorly understood. In this work, we investigate the motion of transition metal ions subject to magnetic fields using 2D numerical simulations. A modified version of the Stefan-Maxwell model is numerically solved for a mixture of ions in aqueous solutions and solved simultaneously with the Navier-Stokes and static magnetic field equations. Simulations are performed in a silica gel based porous medium. Using a finite-element model validated against prior published experimental studies, we demonstrate that solutes can overcome their thermal motion and experience net motion towards strong magnetic gradient fields. Additionally, we found that differences in adsorption activity can cause differences in magnetophoresis of different solutes to deviate from predictions based on magnetic susceptibility.