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Making Salt Water Drinkable Just Got 99 Percent Easier


Stashed in: Science!, Water!

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Humans... you are so selfish. First you suck up all the fresh water, and now you're coming for the salt water.

Fair enough, but you have to admit that the process is cool:

The Reverse Osmosis process works on a simple principle: molecules within a liquid will flow across a semipermeable membrane from areas of higher concentration to lower until both sides reach an equilibrium. But that same membrane can act as a filter for large molecules and ions if outside pressure is applied to one side of the system. For desalinization, the process typically employs a sheet of thin-film composite (TFC) membrane which is made from an active thin-film layer of polyimide stacked on a porous layer of polysulfone. The problem with these membranes is that their thickness requires the presence of large amounts of pressure (and energy) to press water through them.

Lockheed Martin's Perforene, on the other hand, is made from single atom-thick sheets of graphene. Because the sheets are so thin, water flows through them far more easily than through a conventional TFC. Filters made through the Perforene process would incorporate filtering holes just 100 nm in diameter—large enough to let water molecules through but small enough to capture dissolved salts. It looks a bit like chicken wire when viewed under a microscope, John Stetson, the Lockheed engineer credited with its invention, told Reuters. But ounce for ounce, its 1000 times stronger than steel.

"It's 500 times thinner than the best filter on the market today and a thousand times stronger," Stetson explained to Reuters. "The energy that's required and the pressure that's required to filter salt is approximately 100 times less."

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