(686c) Surface Nano-Structuring with Hydrophilic Polymer Brush Layers for Tailored Performance of Fouling Resistant RO and UF Membranes

Surface nano-structuring with hydrophilic polymer brush layers is an effective approach for imparting fouling resistance to membrane surfaces due to improved surface wettability as well as partial chain mobility. In the present approach, a base membrane of a suitable level of rejection and permeability is selected, and its surface is activated via treatment with atmospheric pressure plasma (APP) followed by free radical graft polymerization in an aqueous vinyl monomer solution. The resulting polymer brush layer grafted onto the membrane surface alters the base membrane separation performance (i.e., permeability and solute rejection), which can be tailored by the plasma and graft polymerization conditions. Therefore, selection of the base membrane and the conditions at which surface nano-structuring is performed is critical to achieve a fouling resistant membrane with the target membrane performance. Accordingly, the present study focused on evaluating the impact of plasma surface activation (i.e., APP type and treatment time) and graft polymerization (i.e., monomer type and concentration, grafting temperature and reaction time) conditions on the performance of surface nano-structured (SNS) polyamide (PA) RO and polysulfone (PSf) UF membranes with respect to water permeability and solute rejection. Polymer surface grafting was confirmed via X-ray photoelectron spectroscopy (XPS), and surface wettability and topography of the SNS membranes were evaluated via contact angle measurement and AFM, respectively. Permeability and solute rejection of the SNS-PA and SNS-PSf membranes were evaluated using laboratory scale plate-and-frame and stirred cells, respectively. Fouling propensity of the SNS-PA and SNS-PSf membranes was evaluated using model foulants (i.e., BSA and alginic acid), and membrane cleaning effectiveness was evaluated with DI water flushing at the end of foulant filtration. Results of the present study indicate that the present membrane surface nano-structuring approach is suitable for tailoring the performance of both RO and UF membranes in addition to mitigating membrane fouling and improving membrane cleaning effectiveness.