Graphene oxide/methylene blue composite membrane for dyes separation: Formation mechanism and separation performance

To improve the stability and rejection for dyes of graphene oxide (GO) membrane, we employed methylene blue (MB) as a modifier to prepare GO/MB composite membrane through vacuum filtration. The rejection of GO/MB membrane for different dyes (methyl orange, disperse black 9 and rhodamine B) reached 93.32%, 99.85% and 82.56%, respectively, and the pure water flux was 7.67 L.m(-2).h(-1), indicating that GO/MB composite membranes have good application prospects. The interaction mechanism between GO and MB was described in detail. Moreover, the united-atomic models for molecular dynamics (MD) simulation was performed, through which we can trace the nanoscale events occurring over the interfacial behaviors and provided molecular information at nanoscale interfaces for our study. The effects of the interaction between dye molecules and composite membrane, charges of the dyes, molecular weight and molecular structure of dyes on nanofiltration performance were also discussed, which laid foundation of the research in field of water treatment.