High-performance forward osmosis membrane with ultra-fast water transport channel and ultra-thin polyamide layer

Abstract To further improve the performance of forward osmosis (FO) membrane, a novel composite membrane was formed by introducing graphene oxide and oxidized multi-walled carbon nanotubes interlayer onto electrostatic spinning polyvinylidene fluoride (PVDF) nanofiber mat, in which the hydrophobic channel of PVDF nanofiber substrate was conducive to the rapid transport of water molecules. The interlayer not only provided transfer passage for water molecules, but also decreased the thickness of the polyamide layer. The thickness of the polyamide layer was 85 nm, and decreased by 60% compared with that without interlayer. Thus, the mass transfer resistance was reduced and the flux increased. Meanwhile, the graphene oxide sheets formed a secondary rejection for the salt ions, which resulted in the increase of the water flux without sacrificing the rejection. The forming FO membrane showed super high water flux (305.89 L m−2 h−1) and super low reverse salt flux (0.37 g m−2 h−1) after introducing the interlayer under the condition of using deionized water and 0.6 M NaCl solution as feed solution and draw solution, respectively. It is worth mentioning that its structural parameter was only 82 μm. The performance of the fabricated membrane was superior to the FO membranes reported so far, indicating a simple and practicable way to fabricate high-performance FO membranes with seawater desalination.