Graphene has been tipped as a promising material for this kind of purpose for some time, but previous attempts have failed because graphene oxide membranes swell up when submerged. This allows salt particles to flow through, impeding its ability to properly filter the liquid.
Graphene oxide membranes have already proven their worth in sieving out small nanoparticles, organic molecules and even large salts. But until now, they couldn’t be used to filter out common salts, which require even smaller sieves.
Previous work had shown that graphene oxide membranes became slightly swollen when immersed in water, allowing smaller salts to flow through the pores along with water molecules.