Understanding the effect of hydroxyl/epoxy group on water desalination through lamellar graphene oxide membranes via molecular dynamics simulation

The lamellar graphene oxide (GO) membranes could offer well-defined 2D nanochannels for fast water permeation and excellent ions rejection. In this work, lamellar GO membranes were constructed by stacking GO nanosheets layer-by-layer via molecular simulation. The effect of hydroxyl and epoxy groups as well as their content on the desalination performance in lamellar GO membranes were investigated by molecular dynamics simulation. The transport and separation mechanisms of water molecules and ions passing through the lamellar GO membranes with different functional group were also revealed from thermodynamic and hydrogen bond network. It is found that water flux in GO membranes would be influenced by the order of water molecules and the hydrogen network formed between functional groups and water molecules. GO(OH) membranes showed a higher Na+ rejection rate than Cl- at high hydroxyl contents.