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!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Materials Sciences
23.07.2018 | Information Technology
23.07.2018 | Health and Medicine