(685b) High Performance Magnetically Responsive Membranes for Ultrafiltration

Dong, R., University of Arkansas
Qian, X., University of Arkansas
Wickramasinghe, S. R., University of Arkansas

Membrane fouling is a major problem in numerous membrane based separation processes. During ultrafiltration, membrane performance is compromised by the formation of a concentration polarization boundary layer consisting of rejected species at the membrane surface.  This boundary layer provides an additional resistance to permeate flow, resulting in a decrease in flux. Further, since the concentration of rejected species is higher in the boundary layer than the bulk feed, the apparent rejection coefficient of retained species is often lower.  In addition, concentration polarization can lead to deposition of rejected species on the membrane surface leading to reversible as well as irreversible fouling.

While many surface modification methods have been described that suppress adsorption of rejected species on the membrane surface, they do not suppress concentration polarization.  Here we modify the surface of commercially available nanofiltration membranes in order to impart a magnetically responsive nanostructure.  In an oscillating magnetic field, movement of the grafted polymer chains leads to break up of the concentration polarization boundary layer.  Results presented for BSA filtration indicate higher permeate fluxes in the presence of an oscillating magnetic field.  In addition, use of an oscillating magnetic field leads to greater flux recovery.