Breakthrough made in creation of graphene desalination sieve

Researchers at the University of Manchester have successfully developed a graphene ‘sieve’ that can be used to desalinate seawater.

Graphene sieves could provide solution to clean water shortages

If developed on a larger scale, this could potentially end the struggle millions face to access clean and safe sources of drinking water.

One of the hurdles to taking graphene to a commercial market has been production. Led by Professor Rahul Nair, the team demonstrated how this challenge could theoretically be overcome by using graphene oxide, which – as he explained to the BBC – can be produced by “simple oxidation in the lab”. Graphene oxide is more scalable and cost-effective than graphene, which gives it an advantage when it comes to potential industrialisation.

However, graphene oxide has not previously been suitable for the desalination of common salts, as membranes made from it have a tendency to swell in water and let smaller salt molecules through. The team overcame this by creating walls of epoxy resin on either side of the membrane, which stopped it from expanding in water.

A further benefit of the epoxy resin was the ability it gave the scientists to control precisely the size of the pores in the graphene oxide membrane. This allowed the researchers to create a membrane that prevented common salt molecules from passing through, but allowed water molecules to flow anomalously fast.

“A significant step forward”

“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,” says Prof Nair.

He continues: “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.”

An end to clean water shortages?

The UN recently warned that, by 2025, 14% of the world’s population – equivalent to 1.2 billion – would struggle to access safe and clean water.

Currently, large-scale desalination plants lack efficiency and are expensive to run. However, following this latest development, graphene membranes could one day provide a more efficient means of turning seawater and wastewater into clean drinking water.

It is hoped the technology could ultimately be rolled out in countries that are unable to fund large plants, without compromising the yield of fresh water produced.

Read the study in the journal Nature Nanotechnology.

▲ Up to the top