In this computer simulation, light and dark purple highlight the cavities within the 3D pore structure of CC3.
(Nature Materials 2014)
Scientists have come up with a technique that could make cleaning radioactive elements from the air, such as krypton, xenon and radon, easier and cheaper than current technologies.
While those radioactive materials naturally mix in the air, the quantities are usually low — typically less than one part per million.
The international research team from England, France and the United States, outlined its findings in Nature Materials.
Current methods for removing xenon from the air involve chilling the affected air to a temperature that is much further below the point where water freezes. This can be very expensive and use a lot of energy.
The new technique centers around a new material, CC3, which was developed by research team and members from the University of Liverpool. It’s a molecule that contains a number of cavities, or cages, structured to such an exacting size and shape that radioactive gas molecules of elements like xenon and radon fit very precisely into them.
“If you imagine sorting marbles, then you see the problem with sorting these atoms,” said chemist Andy Cooper from the University of Liverpool and lead study author in a press release. “They are round in shape and of a similar size, not to mention that only one marble in every million is the one you are looking for.”
Researchers performed laboratory experiments and simulations in order find out how effectively the CC3 material was able to separate these radioactive gases.
The CC3 absorbs all types of molecules or atoms that stick to the material’s surface. While only the radioactive gas molecules remain locked into place within the molecular cavities of the CC3, other molecules, such as water or nitrogen, are released.
An animation of a xenon flash lamp being fired. (Gregory Maxwell Wikimedia Commons)
The scientists say that their approach in removing these radioactive materials could prove helpful not only in removing these dangerous airborne elements that result from nuclear fuel clean up or naturally occur in buildings, but could be used to help recycle these elements for future use.
“Xenon, krypton and radon are noble gases, which are chemically inert. That makes it difficult to find materials that can trap them,” said study coauthor Praveen Thallapally of the Pacific Northwest National Laboratory. “So we were happily surprised at how easily CC3 removed them from the gas stream.”
Krypton and xenon gases are used in the manufacture of specialty lighting such as flash lamps and are most popular in photographers’ flash units.
Radon gas can accumulate in buildings, posing a health hazard. According to the U.S. Environmental Protection Agency (EPA), radon causes 21,000 deaths each year in the U.S. alone due to lung cancer.
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