Graphene is the one-atom-thick carbon material that is incredibly strong, stretches a lot without suffering damage and conducts electricity and heat extraordinarily well. These traits have scientists all around the globe playing with it – in the serious way scientists play with stuff – for a range of possible cleantech applications, including photovoltaics.
But the MIT team isn’t focused on the electrical conductivity of graphene; their work is more basic: After doing computer simulations, the researchers believe graphene could be perfect for essentially filtering salt ions out of seawater while letting water molecules run through, producing potable water.
As it stands, desalination plants often use reverse osmosis to produce potable water, and they’ve gotten better at it over the years. But the membranes in use still require high pressure to overcome the natural osmotic pressure of seawater while also blocking salts, and this eats up a lot of energy.
Graphene might be different because it could be possible to create tiny pores – 1 nanonmeter, or a billionth of a meter, wide – that would block the salt ions but would hardly slow down the water molecules. “There’s a sweet spot, but it’s very small,” says MIT’s Jeffrey Grossman, who is the senior author of a paper describing the new process in the journal Nano Letters. At 0.7 nanometers, Grossman said, the system falters, completely blocking the water.
Graduate student David Cohen-Tanugi, lead author of the paper, said the new graphene-based system works “hundreds of times faster than current techniques, with the same pressure,” because of the tremendous strength of graphene.
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