A 'molecular trap' for capturing radioactive iodides in nuclear waste
Seeking a better way to capture radioactive iodides in spent nuclear reactor fuel, Rutgers-New Brunswick scientists have developed an extremely efficient "molecular trap" that can be recycled and reused.
These are two types of cages in the crystal structure of the metal-organic framework, MIL-101-Cr. The yellow spheres represent the pore space for capturing radioactive iodides and have diameters of 29 and 34 angstroms, respectively. An angstrom is one 10 millionth of a millimeter.
Credit: Hao Wang/Rutgers University-New Brunswick
The trap is like a tiny, porous super-sponge. The internal surface area of just one gram of this material could stretch out to cover five 94-by-50-foot basketball courts, or 23,500 square feet. And, once caught inside, radioactive iodides will remain trapped for eons.
"This type of material has tremendous potential because of its high porosity," said Jing Li, distinguished professor in the Department of Chemistry and Chemical Biology at Rutgers University-New Brunswick. "It has far more space than a sponge and it can trap lots of stuff."
Li is corresponding author of a study on molecular traps for nuclear fuel reprocessing that was published in Nature Communications. The first author is Baiyan Li, a former postdoctoral associate in Li's group, and other Rutgers co-authors include doctoral students Hao Wang and Benjamin J. Deibert.
Reprocessing means separating spent nuclear reactor fuel into materials that may be recycled for use in new nuclear fuel or discarded as waste, according to the U.S. Nuclear Regulatory Commission. The U.S. has no commercial reprocessing facilities at the moment, but commercial facilities are operating in other countries.
When spent fuel is reprocessed, radioactive molecular iodine and organic iodide gases that pose cancer and environmental risks must be captured and sequestered. The long-lived gases are hard to capture and can leak into the environment, the Rutgers study says.
Solid adsorbents like silver-infused silica, alumina and zeolites can capture iodides, but their low uptake capacity and poor recyclability make them inefficient and costly, according to Li, who works in the School of Arts and Sciences.
So Rutgers and other researchers developed a "molecular trap" that is made of a highly porous metal-organic framework. Its performance exceeds the standard set by nuclear industry rules, which require waste reprocessing plants to remove more than 99.9 percent of radioactive iodides from spent nuclear fuel rods.
It also far outperforms all current industrial materials in adsorbing, or binding to, radioactive organic iodides. For example, its ability to adsorb methyl iodide at 302 degrees Fahrenheit exceeds that of a benchmark industrial product by more than 340 percent.
Another benefit of the Rutgers molecular trap is that captured methyl iodide can be removed from metal-organic frameworks, enabling their recycling and reuse. This is not possible with current industrial products, from which adsorbent must be sequestered along with captured radioactive iodides.
The metal-organic framework is also cheaper than existing products because it doesn't use silver or other precious metals, and is very robust, able to handle harsh reprocessing conditions such as high temperatures, high acidity and high humidity, Li said.
"We're off to a very good start and we'd like to make improvements," Li said. "Eventually, we hope it can be commercialized."
Todd B.Bates | EurekAlert!
NASA's James Webb Space Telescope completes final cryogenic testing
21.11.2017 | NASA/Goddard Space Flight Center
Previous evidence of water on mars now identified as grainflows
21.11.2017 | US Geological Survey
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
21.11.2017 | Physics and Astronomy
21.11.2017 | Physics and Astronomy
21.11.2017 | Life Sciences