Separation performance and interfacial properties of nanocomposite reverse osmosis membranes

Four different types of nanocomposite reverse osmosis (RO) membranes were formed by interfacial polymerization of either polyamide (PA) or zeolite A-polyamide nanocomposite (ZA-PA) thin films over either pure polysulfone (PSf) or zeolite A-polysulfone nanocomposite (ZA-PSf) support membranes cast by wet phase inversion. All three nanocomposite membranes exhibited superior separation performance and interfacial properties relative to hand-cast TFC analogs including: (1) smoother, more hydrophilic surfaces (2) higher water permeability and salt rejection, and (3) improved resistance to physical compaction. Less compaction occurred for membranes with nanoparticles embedded in interfacially polymerized coating films, which adds further proof that flux decline associated with physical compaction is influenced by coating film properties in addition to support membrane properties. The new classes of nanocomposite membrane materials continue to offer promise of further improved RO membranes for use in desalination and advanced water purification.

Research highlights
► Nanocomposite RO membranes with zeolites in the support membrane and/or thin film.
► Nanocomposites smoother and more hydrophilic than unmodified RO membranes.
► Nanocomposites increase permeability and maintain rejection by molecular sieving.
► Zeolites in support resist physical compaction via enhanced mechanical stability.
► Zeolites in coating resist compaction by mitigating densification of polymer film.