Tag Archives: nuclear waste

Graphene and radioactive waste

In fact, the material in question is graphene oxide and researchers at Rice University (Texas) and Lomonosov Moscow State University have found that it can rapidly remove radioactive material from water  From the Jan. 8, 2013 news item on ScienceDaily,

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 Rice University Jan. 8, 2013 news release, which originated the news item, was written by Mike Williams and provides additional insight and quotes from the researchers (Note: Links have been removed),

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.”

Here’s how it works (from the news release; Note: Links have been removed),

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.

Romanchuk, Slesarev, Kalmykov and Tour are co-authors of the paper with Dmitry Kosynkin, a former postdoctoral researcher at Rice, now with Saudi Aramco. Kalmykov is radiochemistry division head and a professor at Lomonosov Moscow State University. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science at Rice.

Here’s a ‘before’ shot of solution with graphene oxide and an ‘after’ shot where radionuclides have been added and begun to clump,

A new method for removing radioactive material from solutions is the result of collaboration between Rice University and Lomonosov Moscow State University. The vial at left holds microscopic particles of graphene oxide in a solution. At right, graphene oxide is added to simulated nuclear waste, which quickly clumps for easy removal. Image by Anna Yu. Romanchuk/Lomonosov Moscow State University

A new method for removing radioactive material from solutions is the result of collaboration between Rice University and Lomonosov Moscow State University. The vial at left holds microscopic particles of graphene oxide in a solution. At right, graphene oxide is added to simulated nuclear waste, which quickly clumps for easy removal. Image by Anna Yu. Romanchuk/Lomonosov Moscow State University

As noted in the ScienceDaily news item, the research has been published in the Royal Society’s Physical Chemistry Chemical Physics journal,

Anna Yu. Romanchuk, Alexander Slesarev, Stepan N. Kalmykov, Dmitry Kosynkin, James M Tour. Graphene Oxide for Effective Radionuclide Removal. Physical Chemistry Chemical Physics, 2012; DOI: 10.1039/C2CP44593J

This article is behind a paywall.

A brief reference to the Fukushima nuclear accident then, nanotechnology and cleaning up radioactive waste

I came across an excellent article about the Fukushima nuclear accident (courtesy @edyong209) that recounts the first 24 hours of  the emergency. It’s fascinating to find out what they did right and why it all went so wrong in 24 Hours at Fukushima by Eliza Strickland for the November 2011 issue of IEEE Spectrum (published by the Institute of Electrical and Electronics Engineers [IEEE]). Excerpted from the article,

True, the antinuclear forces will find plenty in the Fukushima saga to bolster their arguments. The interlocked and cascading chain of mishaps seems to be a textbook validation of the “normal accidents” hypothesis developed by Charles Perrow after Three Mile Island. Perrow, a Yale University sociologist, identified the nuclear power plant as the canonical tightly coupled system, in which the occasional catastrophic failure is inevitable.

On the other hand, close study of the disaster’s first 24 hours, before the cascade of failures carried reactor 1 beyond any hope of salvation, reveals clear inflection points where minor differences would have prevented events from spiraling out of control. Some of these are astonishingly simple: If the emergency generators had been installed on upper floors rather than in basements, for example, the disaster would have stopped before it began. And if workers had been able to vent gases in reactor 1 sooner, the rest of the plant’s destruction might well have been averted.

Strickland provides some historical context (Three Mile Island and Chernobyl nuclear accidents) in the addition to the 24 hour overview which provides details such as the fact that workers at the plant pulled the batteries out of their cars to generate some form of power after the plant generators failed.

Whether or not you believe we should be using nuclear, there can’t be any question that we have to deal with radioactive waste. From the Strickland article,

… So far, the cost of Fukushima is a dozen dead towns ringing the broken power station, more than 80 000 refugees, and a traumatized Japan.

On that note, the Nov. 2, 2011 news item (Nanotechnology makes storing radioactive waste safer) takes on some urgency. From the news item on Nanowerk,

Queensland University of Technology (QUT) researchers have developed new technology capable of removing radioactive material from contaminated water and aiding clean-up efforts following nuclear disasters.

The technology, which was developed in collaboration with the Australian Nuclear Science and Technology Organisation (ANSTO) and Pennsylvania State University in America, works by running the contaminated water through the fine nanotubes and fibres, which trap the radioactive Cesium (Cs+) ions through a structural change.

By adding silver oxide nanocrystals to the outer surface, the nanostructures are able to capture and immobilise radioactive iodine (I-) ions used in treatments for thyroid cancer, in probes and markers for medical diagnosis, as well as found in leaks of nuclear accidents.

“It is our view that just taking the radioactive material in the adsorbents isn’t good enough. We should make it safe before disposing it,” he [Professor Huai-Yong Zhu] said.

“The same goes for Australian sites where we mine nuclear products. We need a solution before we have a problem, rather than looking for fixes when it could be too late.”

“In France, 75 per cent of electricity is produced by nuclear power and in Belgium, which has a population of 10 million people there are six nuclear power stations,” he said.

“Even if we decide that nuclear energy is not the way we want to go, we will still need to clean-up what’s been produced so far and store it safely,” he said.

There’s no mention of commercializing this means of dealing with radioactive waste but I hope they manage it, or something better,  soon (from the news item),

“One gram of the nanofibres can effectively purify at least one tonne of polluted water,” Professor Zhu said.