Scientists invent Graphene-oxide membranes which turn seawater into drinking water

In a breakthrough invention, scientists have introduced a graphene-based sieve which is capable of removing salt from seawater. The sieve has powers to turn seawater into potable water. In an advance that may provide clean drinking water to millions of people, researchers, including one of Indian origin, from the University of Manchester in the UK, have developed this Graphene sieve.

Graphene-oxide membranes when immersed in water become slightly swollen. Thus, smaller salts flow through the Graphene-oxide membranes along with water, while the larger ions or molecules are blocked.

However, now the researchers have successfully created graphene membranes and have discovered a strategy that would avoid swelling of the membrane when immersed in water.

They said that the membrane’s pore size can be controlled precisely, which can sieve common salts out of the seawater and make it safe to drink.

When dissolved in water, the common salts always form a ‘shell’ of water molecules around the salt molecules. Thus, the tiny capillaries of the graphene-oxide membranes become capable of blocking the salt from flowing along with the water.

Water molecules manage to pass through the membrane barrier and flow anomalously fast which is ideal for application of these membranes for desalination, researchers 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,” said Rahul Nair, professor at University of Manchester.

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“The 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,” said Jijo Abraham of University of Manchester.

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The research was published in the journal Nature Nanotechnology.