(514g) Scale up of RO and UF Membrane Surface Nano-Structuring with Hydrophilic Polymer Brush Layers - Evaluation of Uniformity of Membrane Performance

A novel process of membrane surface nano-structuring with hydrophilic polymer brush layers was evaluated for the scaled-up synthesis of high performance polyamide (PA) RO and polysulfone (PSf) UF membranes. The process is based on surface activation via treatment with atmospheric pressure plasma (APP) followed by free-radical graft polymerization. Surface nano-structuring was evaluated with two types of atmospheric pressure plasma (APP) sources based on air and a helium-oxygen mixture. In order to enable uniform level of surface treatment a robotic system was utilized that can translate the plasma source over a large surface area. Surface graft polymerization was subsequently carried out with acrylic acid (AAc) at various graft polymerization conditions (i.e., initial monomer concentration, graft polymerization time) so as to optimize the synthesized a poly(acrylic acid) (PAAc) polymer brush layer which was confirmed via X-ray photoelectron spectroscopy (XPS). The uniformity of surface activation was evaluated via characterization of surface wettability and topography. At the optimal conditions, membrane sheets of size suitable for 21” spiral-wound RO elements were synthesized. Performance of the nano-structured PA RO and PSf UF membranes, with respect to water permeability and salt rejection, was then quantified for different sections of the large sheet membranes. The results of the current study demonstrate that APPIGP approach can be scaled-up to produce commercial scale surface nano-structured RO and UF membranes.