Graphene-based filters could slash cost of chemical separation and purification

Researchers from the National Graphene Institute at Manchester University have devised a way to turn previously-impenetrable graphene oxide into a selective membrane that can be used to filter even the smallest particles out of fluid mixtures. The discovery could reduce the amount of energy needed for separation processes, which currently require pumps to force liquids through filters, by increasing solvent flow rates.

The team, led by Prof Rahul Nair, also involved colleagues from the School of Chemical Engineering and Analytical Science, and has published its research in Nature Materials. Although graphene oxide membranes have attracted attention for water filtration and desalination applications, until now they have been impenetrable to all solvents apart from water.

Nair’s team has solved this problem buy making the membranes ultra-thin. The membranes are assembled in such a way that minute holes in the structure are connected by grapheme nanochannels, forming an atomic scale sieve that allows all solvents to pass through the structure at high volumes but retaining its impermeability to particles down to the nanometre scale.