(543a) A Bio-Inspired Surface Modification to Improve Membrane Fouling Resistance

Membrane fouling in water purification processes causes dramatic decreases in membrane performance. Membrane surface modifications are effective at remediating fouling of many common contaminants including emulsified oils, proteins, and biofoulants. Here we report a simple and effective membrane modification applicable to any membrane surface. Polydopamine was recently found to non-selectively deposit from solution onto virtually any surface. The polydopamine coating renders the surface very hydrophilic after only a few minutes of contact with dopamine solution. Such short immersion times allow us to achieve the desired surface modification with an extremely thin, conformal coating, avoiding significant membrane flux reduction. Seven membranes of various types were modified using polydopamine and showed reduced fouling while filtering a synthetic oil-water emulsion. Because polydopamine forms a non-selective coating on any surface tested to date, its deposition provides a route to universal membrane modification, eliminating the need to choose membrane-specific chemistries for further surface modification. Poly(ethylene glycol) ad-layer formation on the polydopamine surface further improved membrane performance in oil-water emulsion filtration. Fluxes of modified membranes were maintained at higher levels than those of unmodified membranes. Irreversible fouling was reduced in the modified membranes. Membranes modified with polydopamine and with a grafted poly(ethylene glycol) ad-layer were also tested for protein and bacterial adhesion, precursors to biofilm formation and membrane biofouling. All seven polydopamine- and polydopamine-g-poly(ethylene glycol)-modified membranes showed reduced adhesion of bovine serum albumin protein and Pseudomonas aeruginosa bacteria relative to unmodified membranes. Finally, due to the non-specific nature of polydoapmine deposition, entire membrane modules may be easily modified by flowing dopamine solution through the module, allowing coating of the membrane, spacers, and pressure vessel. Polydopamine deposition is a simple and effective anti-fouling treatment that can be universally applied to membranes of all types and serve as a platform for further surface modification.