Workers stand near pressure vessels at Britain’s first-ever mainland desalination plant, known as the Thames Gateway Water Treatment.
The latest technology for removing salt from seawater, developed by Lockheed Martin, will be a game-changer for the industry, according to Ray O. Johnson, senior vice president and chief technology officer of the jet and weapons manufacturer.
Desalination technology is used in regions of the world, particularly developing countries, where fresh water is not available. Water from oceans or rivers is diverted into treatment plants where the salt is removed and clean drinking water is produced through a process called reverse osmosis.
Imagine a tank with seawater on one side and pure water on the other, separated by a filter with billions of tiny holes. Lots of pressure on the salty side pushes water through faster than the salt, so fresh water comes out the other end.
The problem is that current filters use plastic polymers that use an immense amount of energy (800 to 1,000 pounds per square inch of pressure) to push water through.
Lockheed has developed a special material that doesn’t need as much energy to drag water through the filter.
Graphene is a substance made of pure carbon. Carbon atoms are arranged in a regular hexagonal or honeycomb pattern in a one-atom thick sheet.
This special material is a film of a special structure of carbon, a honeycomb lattice called graphene.
“Graphene is pure carbon that is made in a hot oven on top of a copper sheet
in a vacuum,” John Stetson, the chief technologist at Lockheed for this initiative explained to Business Insider. “Methane gas is put into the vacuum and the methane changes
into a single film of carbon atoms all linked together tightly like chickenwire (at the atomic level) 1,000 times stronger than steel and tolerant of temperature, pressure and pH.”
The sheet is dotted with holes that are one nanometer or less. These holes between carbon atoms trap the salt and other impurities.
Graphene researchers won the Nobel Prize in Physics in 2010 for developing the wonder-material.
In addition, the film is super thin — just a single atom thick — so that the water simply “pops through the very, very small holes that we make in the graphene and leaves the salt behind,” said Stetson.
Lockheed anticipates that their filters will be able to provide clean drinking water “at a fraction of the cost of industry-standard reverse osmosis systems,” their press release says. Water-poor regions of the world will be the first to benefit.
The perforated graphene is aptly called Perforene. Lockheed has the U.S. Patent on this technology and is currently pumping out “pretty big quantities of it” at Lockheed’s advanced technology center in Palo Alto, California, according to Stetson.
The Perforene has a smoky grey-color film that is translucent, even though its carbon, because it is so thin. It’s also about 1,000 times stronger than steel, but still has a permeability that is about 100 times greater than the best competitive membrane out in the market, said Stetson.
Perforene isn’t a game-changer, yet. Lockheed is still in the prototype stage. One challenge is figuring out how to scale up production. Graphene is cheap but it’s very delicate because of its thinness, also making it difficult to transfer.
Stetson says Lockheed is targeting to have a prototype to test in a reverse osmosis plant by 2014 or 2015, where they would simply be able to “plug in” the Perforene to replace the existing filter.
The great news is that this technology is not just limited to desalination plants. It can potentially be used for pharmaceutical filtration, dialysis, and gas separation, to a name a few other uses.
The possibilities are endless.