Scientists create graphene-based sieve that is able to make seawater drinkable

The prospect of drinkable seawater has moved a step closer with the invention of a graphene-based sieve.

The sieve, developed by UK-based researchers, is able to remove any traces of salt – meaning there is a real possibility of providing clean drinking water to millions of people who struggle to gain access.

The team at the University of Manchester, where colleagues won a Nobel Prize in 2010 for first extracting graphene, have managed to precisely control the sizes of pores in a graphene oxide sieve.

Their discovery allows them to filter out salts from water to make it safe to drink, according to the Nature Nanotechnology journal.

Dr Ram Devanathan, from the Pacific Northwest National Laboratory in Richland, wrote: “The ultimate goal is to create a filtration device that will produce potable water from seawater or wastewater with minimal energy input.”

Graphene oxide membranes have already been proven to filter out large salts but it is only now that the team have worked out how to filter out common salts.

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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.

However, the researchers demonstrated that placing walls made of epoxy resin (a substance used in coatings and glues) on either side of the graphene oxide membrane was enough to stop the expansion.

With man-made climate change reducing cities’ water supplies, countries have been increasingly investing in “desalination” technologies.

The UN has predicted that around 1.2 billion people, or 14% of the world’s population, will experience difficulties sourcing clean water by 2025.

Professor Rahul Nair, who led the team of researchers in Manchester, said it is a “significant step forward” that will “open new possibilities for improving the efficiency of desalination technology”.

What is graphene?

Graphene is the world’s first 2D material and was first isolated in 2004. It is incredibly light and flexible but immensely tough – around 200 time stronger than steel. It is the thinnest material on Earth – one MILLION times thinner than the human hair – and acts as a perfect barrier, able to prevent even helium from passing through it. Made up of a hexagonal lattice of carbon atoms in a honeycomb like structure, graphene could one day be used to create flexible phones, wearable technology and lightweight planes.

Top pic: University of Manchester