Assembly of Graphene Oxide Nanosheets on Diamine-Treated PVDF Hollow Fiber as Nanofiltration Membranes

A graphene oxide (GO)-based nanofiltration membrane was fabricated on ethylenediamine-functionalized-polyvinylidene fluoride (EDA-PVDF) hollow fibers. EDA-PVDF was prepared by hydrothermal treatment of polyvinylidene fluoride (PVDF) with ethylenediamine (EDA). On the basis of the interaction of oxygen-containing functional groups of GO and amine groups of EDA-PVDF fiber, a uniform GO layer can be formed in a few seconds by simple immersion of the EDA-cross-linked PVDF fiber in a GO aqueous solution. The GO layer thickness can be controlled from ∼20 nm to several micrometers depending on the concentration of the GO solution (0.5 - 20 mg/mL). The GO layer is shown to be stable in water. The stability is attributed to the EDA in the EDA-PVDF fiber not only forming cross-links between GO and PVDF but also diffusing into the GO interlayer. Filtration tests with dye solutions show that the GO-EDA-PVDF fiber membrane can reject molecules with hydration radii larger than 8 Å (brilliant blue) with rejections (percentage of solute concentration of permeate removed from feed solution by the membrane) of over 95%. Finally, the stable performance of the GO-EDA-PVDF membrane is confirmed by practical crossflow filtration.