Saturday, March 15, 2014

The Key to Large Scale Desalination: Graphene Oxide

With all the promise and hype surrounding the discovery of graphene and the subsequent award of the physics Nobel to Geim and Novoselov you'd have thought the world be transformed by now. I mean it's been almost four years since they got the heads-up from a guy with a Scandinavian accent.
(side note: If someone sounding like the Swedish Chef* calls you some morning in early October, take the call!) 

Well, we may finally have a use for the stuff that makes a real difference.

From Singularity Hub:
Can Graphene Oxide Filters Unlock Our Most Abundant Water Source?
graphene-oxide-water-filter (1)
Humans live on a water world, and yet, many of us still struggle to slake our thirst. Why is that? Earth’s oceans are salty. Just 2.5% of the Earth’s water is freshwater, and of that, 60% is trapped in glaciers, 30% in groundwater (not all of which is accessible), and just 10% is on the surface in lakes and rivers.

There is, of course, great demand for freshwater, and it isn’t all for drinking. Freshwater is used for industrial and agricultural purposes too. Because current methods for removing the salt from ocean water (desalination) are energy intensive and expensive—there is increasing competition for a limited supply of freshwater.

Figuring out how to efficiently remove salt from Earth’s oceans would provide a nearly inexhaustible source of our most precious resource—and wouldn’t you know it? The super material graphene may offer a solution.

Graphene, a one-atom-thick carbon wafer, has been hyped in recent years for its laundry list of useful properties—superconductivity, supercapacitance, and super strength, for example.
Graphene also happens to behave strangely around water.

Its lattice of carbon atoms, akin to chicken wire with nanoscale gaps, allows water through and almost nothing else. Having noted this property, researchers have begun investigating the viability of water filters of graphene.

Last year, Lockheed Martin introduced their Perforene graphene filter. Lockheed claims the filter would reduce energy costs of reverse osmosis desalination 99%.

Desalination plants either use heat to evaporate and re-condense water or force it through a filter (reverse osmosis). The former is obviously energy intensive, but the latter requires large amounts of energy to create pressure and isn’t terribly efficient either. Lockheed’s filter potentially reduces the pressure and therefore energy needed for the process.

“[Perforene is] 500 times thinner than the best filter on the market today and a thousand times stronger,” Lockheed’s John Stetson said. “The energy that’s required and the pressure that’s required to filter salt is approximately 100 times less.”...MORE
*From a prior Nobel Laureate post:

...In the meantime here's Salon on "What do Swedes Think of the Swedish Chef?":

"They think he sounds Norwegian. Also, they’d like you to stop asking"...