(348b) Functionalization of Electrospun Membranes with Polyelectrolytes for Separation of Oil-in-Water Emulsions

Membrane fouling, which is partially determined by the electrostatic interaction between the membrane and emulsions, is one of the major challenges for the widespread of membrane technology in filtration field. To mitigate the effect of fouling, the layer-by-layer (LbL) technique was applied to alter the electrostatic properties of electrospun fiber membranes. This technique consists of plasma pretreatment to charge the pristine membrane and depositions of polycations and polyanions from solutions to build different charged polyelectrolyte layers on top of the pristine membrane. This technique is able to alter the surface charge of the electrospun membranes, while maintaining their interconnected pore structure and high porosity, both of which are preferred to achieve good robustness against fouling and high permeability. The LbL composite membranes were challenged by two types of emulsions, stabilized by anionic and cationic surfactants respectively in dead-end and cross-flow configurations, and the results were compared to those from the untreated membranes. When separating emulsions stabilized by anionic surfactants, the permeate flux of the plasma treated and polyanion-coated membranes increased by 3.2 fold and 2.5 fold respectively, after 4 hours of cross-flow filtration. When separating emulsions stabilized by cationic surfactants, the permeate flux of the polycation-coated membrane was increased by 3.3 fold. This work suggests that electrostatic repulsion can be used to mitigate the effect of fouling, and modification of membrane surface using LbL assembly technique is effective to improve membrane robustness against fouling.