Inventors Geim and Novoselov Hit the Big Time: Graphene Purifies Seawater

Posted: March 20, 2013 by tallbloke in Carbon cycle, Legal
Tags: , ,

grapheneFlashback to 2010:

The prestigious 2010 Nobel Prize for Physics was announced today (October 5), with the prize going to Andre Geim and Konstantin Novoselov, both from the University of Manchester for their work on the development of graphene.

Graphene is a sheet of carbon that is a single atom thick. It is the most efficient conductor of heat known and it conducts electricity as effectively as copper. It is completely transparent, but dense enough to trap helium.

So how did they do it? Gigantic particle accelerator? Interstellar observatory? Witchcraft? None of the above. They used a piece of sticky tape and a pencil to remove a flake of the carbon in the pencil that was one atom thick. Seriously.
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Fastforward to 2013:
(Reuters) – A defense contractor better known for building jet fighters and lethal missiles says it has found a way to slash the amount of energy needed to remove salt from seawater, potentially making it vastly cheaper to produce clean water at a time when scarcity has become a global security issue.

The process, officials and engineers at Lockheed Martin Corp say, would enable filter manufacturers to produce thin carbon membranes with regular holes about a nanometer in size that are large enough to allow water to pass through but small enough to block the molecules of salt in seawater. A nanometer is a billionth of a meter.

Because the sheets of pure carbon known as graphene are so thin – just one atom in thickness – it takes much less energy to push the seawater through the filter with the force required to separate the salt from the water, they said.

The development could spare underdeveloped countries from having to build exotic, expensive pumping stations needed in plants that use a desalination process called reverse osmosis.

“It’s 500 times thinner than the best filter on the market today and a thousand times stronger,” said John Stetson, the engineer who has been working on the idea. “The energy that’s required and the pressure that’s required to filter salt is approximately 100 times less.”

Access to clean drinking water is increasingly seen as a major global security issue. Competition for water is likely to lead to instability and potential state failure in countries important to the United States, according to a U.S. intelligence community report last year.

“Between now and 2040, fresh water availability will not keep up with demand absent more effective management of water resources,” the report said. “Water problems will hinder the ability of key countries to produce food and generate electricity.”

About 780 million people around the world do not have access to clean drinking water, the United Nations reported last year.

“One of the areas that we’re very concerned about in terms of global security is the access to clean and affordable drinking water,” said Tom Notaro, Lockheed business manager for advanced materials. “As more and more countries become more developed … access to that water for their daily lives is becoming more and more critical.”

PRODUCTION CHALLENGE

Lockheed still faces a number of challenges in moving to production of filters made of graphene, a substance similar to the lead in pencils. Working with the thin material without tearing it is difficult, as is ramping up production to the size and scale needed. Engineers are still refining the process for making the holes.

It is not known whether Lockheed faces commercial competition in this area. But it is not the only one working on the technology.

Jeffrey Grossman, an associate professor at the Massachusetts Institute of Technology who has done research on graphene membranes for filtration, said he was not familiar with details of Lockheed’s work. But he said finding a way to produce graphene sheets with nanometer-sized holes could produce a major advancement in desalination efficiency.

“If you can design a membrane that’s completely different than what we use today, then there’s a chance for more than two orders of magnitude (100 times) increase in the permeability of the membrane,” Grossman said.

Stetson, who began working on the issue in 2007, said if the new filter material, known as Perforene, was compared to the thickness of a piece of paper, the nearest comparable filter for extracting salt from seawater would be the thickness of three reams of paper – more than half a foot thick.

Read the rest here.

Comments
  1. Richard111 says:

    Handy to have a portable filter made of that stuff. Problem is the edges must be sharp! Remember reading a science fiction story where they used threads made of something like that. A long molecule. Invisible. Deadly when fixed across a doorway. yuck!

  2. michael hart says:

    Richard111, did you mean “shadow square wire”, Larry Niven’s embodiment of it the concept in “Ringworld”?
    http://en.wikipedia.org/wiki/Ringworld#Concepts
    http://www.technovelgy.com/ct/content.asp?Bnum=930

    Issac Asimov also had a bit a fun with with organic molecules:
    http://en.wikipedia.org/wiki/Thiotimoline

    Graphene isn’t quite as over-hyped, but still seems to be able to perform a remarkable amount of everything for a molecule made only of carbon (i.e. single sheets of graphite), so we shouldn’t be surprised to read reports that it can dice carrots. 🙂

  3. michael hart says:

    …and yes, first (& 2nd) time round I completely failed to register that, like molecular-sheets with sharp edges that apparently dice carrots, the Talk Shop’s banner is currently:

    “Cutting edge science you can dice with.” 🙂

    [Reply] I like to keep people on their toes by changing it regularly, and topically. 🙂