Layered carbon nanotube/polyacrylonitrile thin-film composite membrane for forward osmosis application

A novel thin-film composite (TFC) membrane design with the inclusion of a carbon nanotube (CNT) layer is proposed in this study for forward osmosis (FO) application. A mixed-CNT (mCNT) layer with an interconnecting porous structure and hydrophilic property is placed in between commercially available polyethylene terephthalate (PET) nonwoven fabric and a polyacrylonitrile (PAN) layer fabricated through a simple casting method. A novel method is applied for fabricating a high-quality substrate with a clear-layered structure and higher surface roughness, which can reduce the internal concentration polarization, enhancing the water flux. Subsequently, the molecular layer-by-layer method is utilized for PA deposition on the substrate to prepare the mCNT-containing TFC membrane. Excellent FO properties of 29.04-LMH water flux and 9.41-gMH reserve salt flux are achieved by incorporating the PA layer in the PET30-mCNT-PAN30 substrate, indicating that the proposed CNT-containing TFC membrane has significant potential for FO application.