New Forward Osmosis Polyamide Thin Film Composite Membrane Based On Moderate Hydrophilic Support Layer

Current state-of-the-art polymeric desalination membranes (i.e., RO membranes) show relatively low water fluxes in forward osmosis (FO) mode due to high internal concentration polarization (ICP) caused by large mass transfer resistance in hydrophobic support membranes. To overcome low FO water flux, many studies have focused on the chemical (hydrophilic) and structural modifications of polyamide thin film composite (PA TFC) membranes and cellulose membranes to decrease mass transfer resistance in the support membranes. However, mechanically stable microporous support membranes should be demanded for real-world applications although hydrophilic, highly porous FO membranes exhibit higher FO water flux than commercial RO and FO membranes. Here, carboxylated polysulfones (CPSFs) were considered as moderate hydrophilic, mechanically-stable membrane materials for microporous support layer. The porous support layers using carboxylated polymers and their polyamide TFC FO membranes were prepared to reduce the concentration polarization effect by enhancing the water transport and salt passage in the polymeric support layer. CPSF-based FO membranes showed higher water fluxes than PSF-based FO membranes at the same membrane formation conditions, which might be caused by enhanced hydrophilicity and reduced ICP.