sábado, 12 de enero de 2013

Graphene oxide causes radioactive material to "clump" out of water

January 12, 201
Scientists have discovered that graphene oxide flakes are very effective at removing radioactive contaminants from water (Image: Shutterstock)Image Gallery (2 images)
Removing radioactive material from contaminated water, such as that in Japan’s Fukushima nuclear power plants, could be getting a little easier. Scientists from Houston’s Rice University and Lomonosov Moscow State University have discovered that when flakes of graphene oxide are added to such water, it causes the radionuclides to condense into clumps. Those clumps can then be separated and disposed of.

Presently, bentonite clays and activated carbon are used to remove radioactive contaminants from water. The graphene oxide flakes are reportedly much more effective, however. Their large surface area allows each flake to adsorb a large amount of toxins, and the clumping action occurs within minutes. The clumped material is still radioactive, and must be handled and disposed of accordingly.

In a test of the technique, the one-atom-thick microscopic flakes were added to water containing uranium and plutonium, along with substances like calcium and sodium, that have been shown to negatively affect their adsorption. The graphene oxide was nonetheless able to “clump” the worst toxins quickly, regardless of the water’s pH value.
A vial holding graphene oxide flakes in solution (left), and one in which those flakes have caused simulated nuclear waste to form into clumps (right)
Where you have huge pools of radioactive material, like at Fukushima, you add graphene oxide and get back a solid material from what were just ions in a solution,” said Rice chemist James Tour, who led the research along with Moscow’s Stepan Kalmykov. “Then you can skim it off and burn it. Graphene oxide burns very rapidly and leaves a cake of radioactive material you can then reuse.

Along with its use in disaster scenarios, Tour also believes the technique could be used to remove naturally-occurring radioactive material encountered in hydraulic fracturing (or “fracking”) operations, and in the mining of rare earth metals.

About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

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