Simulation of a Magnetophoretic Device for the Separation of Colloidal Particles in Magnetic Fluids

Magnetophoresis of non-magnetic particles is the induced motion of non-magnetic particles suspended in magnetic media on the application of a magnetic field gradient. It involves many driving forces arising from different transport phenomena. Magnetophoresis can be used in special separation devices to separate colloidal particles based on their sizes. Multiphysics computational programs, such as COMSOL, are ideal for the modeling and simulation of those devices. In this work, we used the calculated magnetic field for a quadruple configuration of permanent magnets to solve the recently-developed magnetophoretic model for the transfer of the non-magnetic colloidal particles due to diffusion, convection, and magnetophoretic forces. The model also takes into account the electrostatic repulsion between the particles. The device chosen for the simulation was similar to a separation device used in an experiment to separate fluorescent polystyrene beads in the size range of 500 to 2000 nm. The two-dimensional results show excellent correlation with the published experimental results. The successful use of COMSOL now opens the door for simulating new devices to arrive at the best configuration of the magnets and flow pathway before building those devices for experimental trials.