Development of Performance-Enhanced Graphene Oxide-Based Nanostructured Thin-Film Composite Seawater Reverse Osmosis Membranes

In this work, the desalination performance of the thin-film composite seawater reverse osmosis membrane (SWRO) was significantly improved by the inclusion of graphene oxide (GO) nanoparticles with a concentration between 0.25 and 1.0% into a polysulfone support (PSfs) membrane. Using an in situ interfacial polymerization method, a polyamide layer was synthesized by using 1,3-phenylene diamine and 1,3,5-benzenetricarboxylic acid chloride on the GO-embedded polysulfone support membrane to fabricate nanostructured thin-film composite seawater reverse osmosis (nTFC-SWRO) membranes. On addition of GO in the PSfs membrane, porosity appeared to show a maximum at 0.5 wt % GO. The hydrophilicity obtained through the water contact angle and surface energy was increased, and the enhanced hydrophilicity of the PSfs also resulted in the enhanced hydrophilicity of the nTFC-SWRO membrane. Raman infrared microscopy characterization established that GO nanoparticles are located on the surface of the PSfs membrane. The nTFC-SWRO membranes displayed over 30% increase in water flux with a slight increase in the NaCl rejection from 98.8 to 99.2% evaluated at 55 bar transmembrane pressure and 32,000 ppm NaCl feed solution. The presence of graphene oxide in the support polymer layer led to the formation of additional channels without introducing defects. nTFC-SWRO membranes were also found to be compaction-resistant than the pure polymeric TFC-SWRO membranes. This method avoids the increased possibility of defects encountered in thin-film nanocomposite membranes where nanoparticles are embedded within the polyamide layer. These high-performance nTFC membranes show excellent promise for commercial exploitation in SWRO.