Graphene carbon shows promise as cheaper heavy-water filter

A model of a graphene molecule
A model of a graphene molecule | Courtesy of the University of Mancherster

One of the most promising materials in modern science is graphene, a two-dimensional honeycomb lattice of carbon that won the 2010 Nobel Prize in Physics.

Potential applications for the material range from biotechnology to batteries; and now one of the scientists who won that Nobel, Andre Gein, and his colleagues at the University of Manchester in England, have begun looking at how this material can change nuclear power.

“Producing heavy water is an expensive process," Marcelo Lozada-Hidalgo, a post-doctoral researcher with the University of Manchester’s School of Physics and Astronomy, recently told Power News Wire. "Graphene membranes could substantially reduce the energy requirements."

Heavy water, or deuterium, is water whose hydrogen atoms carry a neutron and a proton, instead of the proton-only atoms found in protium, the more common form of hydrogen found in regular water. While deuterium occurs naturally, it is found in only one molecule for every 20,000 molecules of normal water. Manchester researchers used a graphene membrane as a sieve to separate deuterium from protium.

Nuclear reactors use deuterium as a coolant and moderator that allows the use of natural, unenriched uranium as a fuel source. The methods of harvesting deuterium from regular water have, until now, been excessively expensive, however. Graphene sieves could change that.

“We have shown that the technology is scalable and ready to use," Lozada-Hidalgo said. "The implementation timelines would then depend on industrial partners. Like any new technology, it must be adapted to the current state-of-the-art facilities.”

The same technology could be applied to other parts of the nuclear process as well. When deuterium captures a neutron, it becomes the radioactive version of heavy water, tritium. Graphene membranes also can separate tritium from water and deuterium, both to remove the radioactive substance from the environment and to harvest it for use in experimental reactor designs.

“Graphene membranes are the first membranes shown to separate isotopes of hydrogen at room temperature," Lozada-Hidalgo said. "We expect they will quickly find their way into industrial applications. Indeed, membranes are used across industry to separate species efficiently, and now we have shown that graphene is the membrane with ultimate selectivity -- subatomic.”

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University of Manchester

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