No abstract

Graphene oxide (GO), as an emerging nanofiller, is commonly incorporated into the polypiperazine amide (PPA) selective layer to enhance nanofiltration (NF) performance. However, GO’s dispersibility and compatibility present outstanding challenges for fabricating high-performance GO-incorporated NF membranes. In this study, polyvinyl alcohol (PVA) and GO were introduced into the aqueous solution at the same time to enhance the membrane performance by taking advantage of the synergetic effects of GO and PVA. GO’s dispersibility in aqueous solution and its compatibility within the PPA matrix were significantly improved because of the introduction of PVA. Furthermore, both PVA and GO contributed to the diffusion behavior of aqueous monomers for constructing defect-free, rougher, thinner, and more hydrophilic NF membranes. With the introduction of 100 ppm GO and 0.05 wt % PVA into the aqueous solution during the interfacial polymerization process, the optimal thin-film nanocomposite NF membrane exhibited a water flux of 84.2 LMH without reducing the salt rejections (97.6% for Na2SO4), which were 69.1 and 36.7% higher than the pristine thin-film composite (TFC)-blank and TFC-PVA membranes, respectively. Meanwhile, an excellent antifouling performance was achieved with a flux recovery rate of 92.1% because of the lower negative charge and excellent hydrophilicity of the membrane surface. This study develops a simple and effective approach to construct high-performance NF membranes.