Graphene oxide has a remarkable ability to quickly remove radioactive material from contaminated water, researchers at Rice University and Lomonosov Moscow State University have found.
A collaborative effort by the Rice lab of chemist James Tour and the Moscow lab of chemist Stepan Kalmykov determined that microscopic, atom-thick flakes of graphene oxide bind quickly to natural and human-made radionuclides and condense them into solids. The flakes are soluble in liquids and easily produced in bulk.
The experimental results were reported in the Royal Society of Chemistry journal Physical Chemistry Chemical Physics.
The discovery, Tour said, could be a boon in the cleanup of contaminated sites like the Fukushima nuclear plants damaged by the 2011 earthquake and tsunami. It could also cut the cost of hydraulic fracturing ("fracking") for oil and gas recovery and help reboot American mining of rare earth metals, he said.
Graphene oxide's large surface area defines its capacity to adsorb toxins, Kalmykov said. "So the high retention properties are not surprising to us," he said. "What is astonishing is the very fast kinetics of sorption, which is key."
"In the probabilistic world of chemical reactions where scarce stuff (low concentrations) infrequently bumps into something with which it can react, there is a greater likelihood that the 'magic' will happen with graphene oxide than with a big old hunk of bentonite," said Steven Winston, a former vice president of Lockheed Martin and Parsons Engineering and an expert in nuclear power and remediation who is working with the researchers. "In short, fast is good."
Determining how fast was the object of experiments by the Kalmykov group. The lab tested graphene oxide synthesized at Rice with simulated nuclear wastes containing uranium, plutonium and substances like sodium and calcium that could negatively affect their adsorption. Even so, graphene oxide proved far better than the bentonite clays and granulated activated carbon commonly used in nuclear cleanup.
Graphene oxide introduced to simulated wastes coagulated within minutes, quickly clumping the worst toxins, Kalmykov said. The process worked across a range of pH values.
"To see Stepan's amazement at how well this worked was a good confirmation," Tour said. He noted that the collaboration took root when Alexander Slesarev, a graduate student in his group, and Anna Yu. Romanchuk, a graduate student in Kalmykov's group, met at a conference several years ago.
The researchers focused on removing radioactive isotopes of the actinides and lanthanides – the 30 rare earth elements in the periodic table – from liquids, rather than solids or gases. "Though they don't really like water all that much, they can and do hide out there," Winston said. "From a human health and environment point of view, that's where they're least welcome."
Naturally occurring radionuclides are also unwelcome in fracking fluids that bring them to the surface in drilling operations, Tour said. "When groundwater comes out of a well and it's radioactive above a certain level, they can't put it back into the ground," he said. "It's too hot. Companies have to ship contaminated water to repository sites around the country at very large expense." The ability to quickly filter out contaminants on-site would save a great deal of money, he said.
He sees even greater potential benefits for the mining industry. Environmental requirements have "essentially shut down U.S. mining of rare earth metals, which are needed for cell phones," Tour said. "China owns the market because they're not subject to the same environmental standards. So if this technology offers the chance to revive mining here, it could be huge."
Tour said that capturing radionuclides does not make them less radioactive, just easier to handle. "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," he said. "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."
The low cost and biodegradable qualities of graphene oxide should make it appropriate for use in permeable reactive barriers, a fairly new technology for in situ groundwater remediation, he said.
Rice University: http://media.rice.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Institute for Highway Safety is known for crash-test safety ratings, but as cars get smarter there's a need to look beyond crashworthiness
Researchers have long struggled to resolve what happens to information when it falls inside a black hole, but the famous physicist says he has a solution
Researchers have been using muons to take a peek inside the nuclear reactors in Japan that melted down in 2011. The results could aid the continuing cleanup operations.
Neutrinos, created by violent phenomena such as black holes and exploding stars, could hold the key to the universe’s most distant and mysterious events
Better MRI scanners could result from a trick in which a magnetic field springs up from nowhere, using materials famous for their link to invisibility cloaks
Water locked away in rocks for 1.5 billion years reveals conditions were right for complex organic molecules to form in deep sea hydrothermal vents
Helium, used in nuclear, medical and, yes, party industries, has become scarce, but new research has revealed a possible way to pinpoint fresh sources
New lab results show how collisions between comets and planets can make the molecules that are the essential building blocks of life.
A startup company says it is expanding the language of DNA to create new tools for drug discovery.
If scientists can convince people to use the app, they hope it will help them solve a cosmic mystery. This story originally aired on March 27, 2015 on All Things Considered.