High performance polyacrylonitrile-supported forward osmosis membranes prepared via aromatic solvent-based interfacial polymerization

A high performance thin film composite (TFC) forward osmosis (FO) membrane was prepared using a hydrophilic polyacrylonitrile (PAN) support with a tailored structure via a newly devised, aromatic solvent (toluene)based interfacial polymerization (TIP) technique. The use of toluene as the organic solvent promoted amine diffusion toward the organic phase and the subsequent reaction, leading to the formation of an ultrathin (highly permeable) and highly dense (highly selective) polyamide selective layer on the PAN support, which improved membrane performance. In addition, a relatively thin (similar to 80 mu m) and finger-like porous support structure embedded with a nonwoven fabric was favorable for facilitating mass transport in the support. As a result, the TFC FO membrane prepared via TIP showed similar to 2.1 times higher FO water flux and similar to 68% lower specific salt flux than the membrane prepared via conventional aliphatic solvent-based interfacial polymerization (IP) in FO mode. Importantly, our TIP-assembled membrane exhibited superior FO performance over commercial and other lab-made membranes. Our strategy provides a facile solution to overcome the technical limitations of the conventional IP method by enabling the fabrication of high performance PA layers on hydrophilic supports, expanding the application spectrum of TFC membranes.