Salt could be separated from water using an ultrathin porous membrane made up of a single sheet of carbon atoms, a computational study suggests.
David Cohen-Tanugi and Jeffrey Grossman at the Massachusetts Institute of Technology in Cambridge simulated the molecular interactions between graphene, salt and water, and looked at the effects of different pore sizes on salt filtration. The researchers found that graphene with a pore size of 0.7–0.9 nanometres should stop the passage of salt while letting water through. Attaching hydroxyl groups to the edges of the graphene pores would boost water flow-rate but impair salt rejection — because the chemical groups can swap with water molecules surrounding the salt ions. By contrast, attaching hydrogen atoms to the pores would improve filtration.
Graphene promises to be many times more permeable to water than conventional membranes used in desalination, the authors say.
Nano Lett. http://dx.doi.org/10.1021/nl3012853 (2012)