Polydopamine/Imogolite Nanotubes (PDA/INTs) Interlayer Modulated Thin Film Composite Forward Osmosis Membrane For Minimizing Internal Concentration Polarization

Forward osmosis (FO) as an energy-saving membrane process has attracted much attention in food concentration, water treatment, and desalination. Thin film composite (TFC) membrane is the most popular FO membrane, but it suffers from the internal concentration polarization (ICP), which significantly limits the water flux and FO efficiency. In this report, we demonstrate a novel and high-performing thin film nanocomposite (TFN) membrane that employs a hydrophilic interlayer composed of imogolite nanotubes (INTs) and polydopamine (PDA). The INTs can be adhered to the porous substrate by the self-polymerization of PDA, and the as-prepared PDA/INTs interlayer displays a nanostructured network with outstanding hydrophilicity. The detailed investigation was conducted to understand the relationship between the structure and property of the PDA/INTs interlayer and the morphology and performance of the TFN membrane. The TFN membrane with the PDA/INTs interlayer performs a thinner and smoother polyamide selective layer. Correspondingly, the TFN membrane shows a water flux of 18.38 L center dot m(-2)center dot h(-1), which is 2.18 times of the pristine TFC membrane. Moreover, the TFN membrane has a minimized structural parameter (577 mu m), almost a half of that of the pristine one (949 center dot m). It reveals that the ICP effect of TFC membrane can be effectively alleviated by using a hydrophilic PDA/INTs interlayer. This TFN membrane with a satisfactory water permeability is promising in terms of future applications.