Enhancing the Permeability and Fouling Resistance of Thin-Film Composite Forward Osmosis Membranes via Poly(ethylene glycol) Diamine as a Comonomer

In this study, poly(ethylene glycol) diamine (PEG-diamine) was proposed to be used as a key functional monomer to modify the conventional polyamide thin-film composite (PA-TFC) membrane via interfacial polymerization (IP). PEG-diamine with end amine functional groups could participate in IP reaction and change the morphology and chemistry of the PA layer. Thus, PEGdiamine was incorporated into the active layer during IP reaction, and then, its loading effects on the PA layer surface properties and separation performances were investigated thoroughly. Modified membranes revealed a more hydrophilic and smoother surface than the control TFC membrane, resulting in improved separation performance. Indeed, the PEG-diamine controls the diffusion of MPD monomers to the reaction side, modifying PA layer properties. Compared with the pristine membrane, the water flux of the TFCPEG-diamine-0.2 membrane increased by about 200% without sacrificing the reverse salt flux. Furthermore, the TFC-PEG-diamine 0.2 membrane has excellent antifouling properties against sodium alginate foulant. Therefore, this work presents a simple and facile route to prepare PA-TFC membranes with good stability, high hydrophilicity, high performance, and strong fouling resistance.