Covalent cross-linking mediated TA-APTES NPs to construct a high-efficiency GO composite membrane for dye/salt separation

The excellent water transport and molecular sieving properties of graphene oxide (GO)-based membranes have shown application prospects in solving the freshwater crisis. However, it is challenging to further increase water permeability while ensuring separation efficiency, and the destruction of the membrane structure caused by the electrostatic repulsion between the graphene oxide nanosheets also hinders its practical application. In this study, a simple vacuum-assisted method is proposed to prepare a chemical cross-linking mediated composite graphene oxide nanofiltration membrane (GO-TA-APTES-x) by adding tannic acid (TA)-aminopropyltriethoxysilane (APTES) nanoparticles (TA-APTES NPs). Thanks to the expansion of GO membrane interlayer spacing by TA-APTES NPs, the permeability of the GO-TA-APTES-10 membrane is 15 times higher than that of the original GO membrane, and the rejection rate of Congo red remains at 99.9%. In addition, TA-APTES NPs improves the application stability of composite membrane in water environment by means of chemical crosslinking agent, which is expected to promote the transformation of GO nanofiltration membrane from the laboratory environment to industrial application.