Bioinspired graphene oxide nanofiltration membranes with ultrafast water transport and selectivity for water treatment

This picture shows the separation effect of the composite membrane composed of graphene oxide and chitosan in water and water treatment, showing excellent performance in the field of nanofiltration. [Display omitted] •Inspired by cell membranes, graphene oxide-chitosan composites were used for dye separation nanofiltration membranes.•A composite membrane was prepared on a cellulose acetate carrier by vacuum filtration.•The water permeability and dye repellency of the obtained membrane were significantly improved.•The composite membrane has long-term stability over a wide pH range. The weak interlayer interactions and poor mechanical stability of graphene oxide (GO) membranes pose significant challenges in any practical application environment. Moreover, the layered stacked GO membranes have low water permeability and low selectivity for small molecules due to their inherent nano-interlayer channels. In order to solve the problems of mechanical properties and size control of interlayer nanochannels, we synthesized GO-chitosan (GO-CS) composites with covalent bonds by a one-step hydrothermal method, and prepared a series of composite membranes by vacuum filtration. The GO-CS composite membrane resulted in a widened and defined two-dimensional (2D) channel due to the intercalation of GO-CS. The prepared GO-CS composite membrane has the highest water permeability of 107.4 L·m−2·h−1·bar−1, which is nearly 4 times that of the GO membrane. Almost complete of methylene blue (MnB), Congo red CR), rhodamine B (RB) dye molecules, with excellent molecular sieving ability. Furthermore, the presence of covalent bonds between GO and CS resulted in significantly enhanced membrane stability. We aim to provide potential applications for next-generation nanofiltration membranes by tuning the microstructure of the membranes.