(706b) Hydrodynamic Permeability of Nanoparticle Modified, Thin Film Composite Membranes

 Luis Escobar-Ferrand (1, 2); Christian Lubombo (1); Amrut Biswal (1); Ji Seung Kim (1) and Christopher J. Durning (1)

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

(2) Pall Corporation, Port Washington, NY 11050

Layer by Layer (LbL) deposition of primarily inorganic silica nanoparticles enabled surface modification of polymeric micro and ultrafiltration (MF/UF) membranes to produce thin film composite (TFC) membranes with potential nanofiltration (NF) capabilities. The hydrodynamic permeability of these TFC’s is measured to evaluate their performance under typical operating conditions using dead-end permeation experiments. Several combinations of substrates and nanoparticles both spherical (cationic/anionic) and elongated (anionic) silica nanoparticles were tried and compared with realistic hydrodynamic models obtaining positive results. Surface modification results in permeability reduction of approximately two orders of magnitude with respect to the bare substrates to values comparable to those for typical commercial NF membranes. Comparison and good agreement with theoretical hydrodynamic models with no adjustable parameters was also established providing indirect confirmation that the surface layers are largely defect (crack) free. Imaging of our TFC membranes after permeation tests confirmed no significant mechanical damage, that is integrity and robustness of the TFC produced in typical applications.   

The work supports that nanoparticle based LbL surface modification of MF/UF membranes can produce filtration quality media, achieving goals for particular and specific membrane water applications, such as nanofiltration (NF) softening processes, natural organic matter (NOM) elimination and possibly reverse osmosis (RO) desalination.