(698e) A Simple Bioinspired Surface Modification to Improve Water Purification Membrane Separation Efficiency

Membrane fouling is problematic in water purification processes and causes dramatic decreases in membrane performance. Membrane surface modifications have been effective at remediating fouling of a number of common contaminants, including emulsified oils, proteins, and biofoulants. Nevertheless, many problems arise with most surface modifications. For example, processes, such as plasma treatment, to introduce radicals into the polymer backbone, and multi-step organic reactions are difficult to accomplish when considering large-scale operations. Here we report an effective, yet simple membrane modification that can be universally applied to all membranes. Polydopamine was recently found to non-selectively deposit from solution on virtually every surface with which it came into contact. Seven membranes with various properties 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 so far tested, its deposition provides a route to universal membrane modification, eliminating the need to choose appropriate, membrane-specific chemistries for further surface modification. Poly(ethylene glycol) ad-layer formation on the polydopamine surface further improved membrane performance. Membranes modified with polydopamine and with an additional poly(ethylene glycol) ad-layer were also tested for protein and bacterial adhesion. Protein and bacteria adhesion, a precursor to biofilm formation and membrane biofouling, universally occurs in water treatment facilities and in membrane bioreactors. All seven polydopamine-modified membranes showed reduced adhesion of bovine serum albumin relative to unmodified membranes. Futher reduction in adhesion of BSA was observed for membranes with an additional poly(ethylene glycol) ad-layer. Adhesion of Pseudomonas aeruginosa, a bacterium commonly found in freshwater drinking reserves and a notorious cause of robust biofilm growth in water purification operations, was also explored and will be presented. The simplicity and versatility of polydopamine deposition on membranes gave it distinct advantages over other common modifications.