Molecular insights into desalination performance of lamellar graphene membranes: Significant of hydrophobicity and interlayer spacing

Abstract

The multilayer graphene-based membranes have shown well prospect in seawater desalination application owing to their well-defined 2D for rapid water penetration and excellent ion rejection. In this work, the lamellar GRA-X membranes with different hydrophilicity were constructed by stacking functional graphene sheets layer-by-layer. The effect of interlayer spacing and the hydrophilicity of membranes on desalination performance was discussed. The relationship between the hydrophilicity of GRA-X membranes and water flux was also explored by non-equilibrium molecular dynamics simulations (NEMD). It was found that the water flux in GRA-X membranes increased with the decrease hydrophilicity of graphene membrane, and it could be regulated by adjusting the interaction between water molecules and functional groups or controlling the order of water molecules in the pore channels. The rejection rate was mainly determined by the effective distance of interlayer spacing in GRA-X membranes.