Novel Antifouling Reverse Osmosis Membranes Grafted with Biocidal Silver Nanoparticles and Antifouling Polymer Brushes

摘要

Thin-film composite (TFC) polyamide reverse osmosis (RO) membranes are prone to biofouling due to its inherent physicochemical surface properties. In order to address the bio-fouling problem, we have developed novel surface coatings via polyelectrolyte layer-by-layer (LBL) self-assembly, functionalized with biocidal nanoparticles and antifouling polymer brushes. The novel surface coating is prepared with polyelectrolyte [PEI: poly(ethylene imine); PAA: poly(acrylic acid) (PEI/PAA)] LBL films containing PEI coated silver nanoparticles (Ag-PEI), grafted either with hydrophilic [poly(sulfobetaine)] or with low surface energy [poly(dimethylsiloxane), PDMS] polymer brushes. Coating with both LBL films and sulfobetaine polymer brushes significantly increases the hydrophilicity of the membrane surfaces. Overall, surface modifications resulted in significant reduction of bacterial cell adhesion. In static bacterial adhesion tests with E. coli K12 MG1655, a normalized cell adhesion in the range of only 4 to 16% on the modified membrane surfaces is observed. Modified surfaces containing silver nanoparticles are also noted to have strong antimicrobial activity. The membranes containing bilayers of PAA/100% Ag-PEI are observed to achieve over 95% inactivation of bacteria attached to the surface within 1 hour of contact time. Both antifouling and antimicrobial results suggest the potential of using these novel surface coatings in controlling the fouling of RO membranes.