Towards Filtration of Oil-Water Mixtures Using Rotating Flow and Hydrophilic Membranes

This research aims to combine hydrophilic membranes with rotating flow to treat oil-water mixtures that result from oil spills and oil production.  The hypothesis of the work is that rotational flow, particularly that in a hydrocyclone, will force oil droplets away from a membrane surface, and hydrophilic coatings will also decrease fouling.  Simulations and fouling studies with rotating membranes and buoyant, glass beads demonstrate that with sufficiently large particles, centripetal forces prevent the beads from fouling the membrane wall.  Similar effects should occur with oil droplets in a rotating flow.   Upon immersion in water, hydrophilic membrane coatings such as polymer brushes and polyelectrolyte multilayers swell to become oleophobic, and oil dewets from these surfaces.  Moreover, when the oil surfactants have the same charge as the polyelectrolyte coating, oil rejection increases in dead-end filtration, even when membrane pores are much larger than the droplets.    Similar experiments with neutral surfactants show no oil rejection.  Thus, the choice of the emulsion surfactant should alter both fouling and rejection.   The combination of rotating flow and membrane modification may significantly enhance the role of membrane processes in treating oil-water mixtures.