Scientists at The University of Manchester have created a graphene-based sieve capable of removing salt from seawater.

Graphene-oxide membranes have already demonstrated to have the potential of filtering out small nanoparticles, organic molecules and even large salts. However, until now, they couldn’t be used in desalination for sieving common salts, which require even smaller sieves.

Previous research at the University of Manchester found that, if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the enlarger holes in the membrane along with water.

The Manchester group has now further developed these graphene-oxide membranes and found a way to avoid the swelling of the membrane when exposed to water by coating both sides of the membrane with epoxy resin.. The pore size in the membrane can be precisely controlled to sieve common salts out of salty water and make it safe to drink.

The researchers have also demonstrated that there are realistic possibilities of scaling up the approach to mass produce graphene-based membranes with required sieve sizes. Graphene oxide can be produced as an ink or solution by simple oxidation. It can then be composed on a substrate or porous material which can be used as a membrane.