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, PEG-diamine 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 TFC-PEG-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.