Graphene oxide composite membranes with amazing stability in water

Graphene oxide (GO) membranes are outstanding candidates for water treatments thanks to the fast water permeation through two-dimensional nano capillaries, combined with size and electrostatic ion exclusion mechanisms. However, their use for aqueous separations processes is limited due to swelling phenomena, which reduce both the selectivity and mechanical stability of GO laminates. Here, we demonstrate an easily scalable method with a low environmental impact exploiting GO self-assembly on a porous polymeric film driven by attractive electrostatic interactions to produce GO membranes with excellent stability in water and saline solutions. The experimental results highlight the key role of support chemistry, surface charge and topography to obtain composite membranes free from swelling or delamination issues. The composite GO membranes developed represent a further step ahead toward the large-scale application of GO-based membranes in separation processes. Beyond the exceptional stability of these nanocomposite systems, they present a water flux higher than that predicted for a viscous flow. Moreover, these composite membranes are also stable in organic solvents and they might be potentially used in organic solvent nanofiltration.