Graphene sieve transforms seawater into drinking water
© University of Manchester

Graphene sieve makes seawater drinkable

New research has demonstrated the potential of providing clean drinking water to millions of people through graphene-based filtration technologies.

The new findings from a group of scientists at the University of Manchester (UoM), UK, were published in the journal Nature Nanotechnology.

Graphene-oxide membranes developed at the National Graphene Institute have already demonstrated the potential of filtering out small nanoparticles, organic molecules, and even large salts. Until now, however, they couldn’t be used for sieving common salts used in desalination technologies, which require even smaller sieves.

Previous research at UoM found that if immersed in water, graphene-oxide membranes became slightly swollen and smaller salts flew through the membrane along with water, but larger ions or molecules were blocked.

The Manchester-based group have now further developed these graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water. The pore size in the membrane can be precisely controlled which can sieve common salts out of salty water and make it safe to drink.

Professor Rahul Nair of UoM said: “Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology.

“This is the first clear-cut experiment in this regime. We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes.”

Jijo Abraham, one of the joint-lead authors on the research paper, added: “The developed membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.”

By 2025 the UN expects that 14% of the world’s population will encounter water scarcity. This technology has the potential to revolutionise water filtration across the world, particularly in countries that cannot afford large-scale desalination plants.