Highly hydrophilic thin-film composition forward osmosis (FO) membranes functionalized with aniline sulfonate/bisulfonate for desalination

Appropriate membranes are crucial to maximize the potential of forward osmosis (FO) in water treatment. In this study, high-performance and well-constructed thin-film composite (TFC) FO membranes were developed via chemical modifications for FO desalination. The newly developed membranes consist of an aniline sulfonate/bisulfonate functionalized polyamide layer formed by interfacial polymerization on a poly(ether sulfone) (PES) support. Aniline sulfonate/bisulfonates were covalently bonded to the nascent polyamide layer by the acylation reaction between primary amine and acyl chloride groups. The novel membranes have more hydrophilic and smoother surfaces which are important to increase antifouling capability, thus conducing to improved water transfer rates. The 2,5-disulfoaniline disodium salt (DSA-2Na) modified membrane produced water fluxes 71.5% and 52.0% higher than the pristine membrane under the respective PRO (draw solution facing the active layer) and FO (feed solution facing the active layer) modes against DI water. With simulated seawater as the feed and 2.0 M MgCl2 as the draw solution, DSA-2Na modified membrane created a water flux of 16.7 LMH (FO mode), a 36% increase compared to the pristine membrane with a water flux of 12.3 LMH. This is comparable to the best value reported for seawater desalination, indicating the superiority of the aromatic sulfonate/bisulfonate materials functionalized membranes in FO membrane separation.