LAUSR

Abstract Graphene based membranes are widely used in the separation of various molecules and ions due to their unique size barrier properties. Here, a hydroxylated graphene (GOH) and graphene oxide (GO) composite nanofiltration membrane was prepared by vacuum filtration. GO was hydrophilic and softly and easily to wrinkle and stack into a dense GO membrane. GOH, which contained more sp2 hybridized aromatic ring structures, was more rigid than GO sheets and tended to form loose porous structure. It could be found that GOH was well embedded into the soft layer of GO to form a membrane. Then, the performance of the composite membrane (GO/GOH) was evaluated through typical dye molecules and proteins. When the GOH content in the composite membrane was less than 50 wt%, it had no significant effect on the retention of methyl orange (MO), rhodamine B (RhB) and bovine serum albumin (BSA) (> 99.4), but the pure water permeability was 3.6–4.5 times that of the pure GO membrane, reaching 22.7-26.5 L m−2 h-1. In this work, the superior water flux of the GO/GOH composite membrane compared to the reference GO membrane was mainly attributed to the moderate increase of interlayer spacing and nanochannels of the membrane.