(601b) Nanoparticle Only Layer by Layer Surface Modification of Microfiltation/Ultrafiltration (MF/UF) Membranes

Luis Escobar-Ferrand (1, 3), Lydia Ngai (1), Christopher Durning (1), Diya Li (2), Daeyeon Lee (2), Tom Gsell (3) and Amarnauth Singh (3)

(1) Department of Chemical Engineering, Columbia University, New York, New York 10027

(2) Department of Chemical and Biomolecular Engineering University of Pennsylvania, Philadelphia, PA 19104

(3) Pall Corporation - 25 Harbor Park Drive, Port Washington, NY 11050

            Layer by Layer (LbL) deposition using primarily inorganic silica nanoparticles is employed for the modification of polymeric micro and ultrafiltration (MF/UF) membranes. A variety of porous substrate membranes are employed, all exhibiting moderate hydrophobicity including polycarbonate track etched (PCTE), polyethersulfone (PES) and sulfonated PES (s-PES) MF/UF membranes.    Both spherical (cationic/anionic) and elongated (anionic) silica nanoparticles are deposited using conditions similar to those reported by Lee et al [1]. Appropriate selection of the pH’s for anionic and cationic particle deposition enables the construction of nanoparticle only layers 100-200 nm in thickness atop the original membrane substrates. The surface layer thickness varies monotonically with the number of bilayers (anionic/cationic deposition cycles) as expected. The deposition process is optimized to eliminate drying induced cracking and to improve mechanical durability via thickness control and post-deposition hydro-thermal treatment. The work suggests that nanoparticle based LbL surface modification can be systematically manipulated to achieve goals for particular membrane applications, e.g. nanofiltration (NF) softening processes, natural organic matter (NOM) elimination and reverse osmosis (RO) desalination.

[1]. D. Lee, M.F. Rubner, R.Cohen , Nanoletters 2006, 6, 2305-2312