Nanoparticle-embedded nanofibers in highly permselective thin-film nanocomposite membranes for forward osmosis

Here we report a scalable approach to fabricate osmotic membranes with high permselectivity based on nanocomposite of mesoporous silica nanoparticles and nanofibers by electrospinning. Transmission electron microscopy (TEM) images provide visualization of dispersed and clustered nanoparticles embedding within or at the surface of nanofibers. Energy-dispersive X-ray (EDX) point analysis confirms the chemical identity of the nanocomposite structure. Brunauer-Emmett-Teller (BET) analyses show a 75-fold increase in specific surface area when 15% of silica nanoparticles were integrated into polyacrylonitrile nanofibrous mats. Mechanical strength tests show that even at high load of silica nanoparticles, e.g. 15 wt%, the mechanical integrity of the membranes was maintained. Incorporating nanoparticles into nanofibrous mats enhanced their water uptake up to two times. In osmotic transport studies, we observed an outstanding permselectivity of our membranes compared to ones reported in literature. Our membranes show a remarkable 7-fold and 3.5-fold enhancements in osmotic water permeability and water/sodium chloride selectivity, respectively, compared to standard commercial forward osmosis membranes. These results suggest a pathway to develop scalable, high performance osmotic membranes and to further study the predominant mechanism governing transport behaviors of water and solute across nanomaterials interfaces.