RICHLAND, Wash. – While useful in small amounts to scan and diagnose thyroid disease, a radioactive chemical called pertechnetate is a bad actor when it’s in nuclear waste tanks.
Pertechnetate is the soluble form of technetium-99, a radioactive byproduct of nuclear weapons production with a very long half-life. Since it is water soluble, it has a high potential for spreading and contaminating the environment if it were to leak out of tanks where radioactive wastes are held — like at the Hanford Site in Washington state.
PNNL materials scientist Praveen Thallapally is familiar with the makeup of Hanford tank waste from previous projects. While collaborating with USF on another project, he learned researchers had developed an organic material with many nano-sized pores, which are about one-billionth of a meter. Thallapally recognized its properties would attract and trap pertechnetate within those pores. Inspired, the research team did extensive testing of the material using simulated waste and recently published its findings in Nature Communications.
“This is the best material reported to date in terms of its affinity towards pertechnetate and record-high extraction efficiencies,” Thallapally said. “After running a pertechnetate simulant through a glass column of the material, the concentration dropped from 1,000 parts per billion to just one part per billion.”
The powdery material has a high surface area with many active sites that specifically attract and bind the pertechnetate. It’s also durable even when exposed to radiation and to the environments found in nuclear waste tanks at EM’s Savannah River and Hanford sites. The material is also reusable: it can release the pertechnetate attached to the material and then adsorb more.
The researchers report that existing commercially available resins are inefficient in capturing pertechnetate and have a much lower surface area that requires a greater quantity of resin to reduce the concentration of the contaminant.
“We believe the material could become highly influential for nuclear wastewater treatment technologies,” Thallapally said of this early-stage research. “In a perfect world, I’d like to see this technology applied to tank waste treatment in hopes of achieving cost savings and accelerating the cleanup schedule. I think it would have a positive impact.”
Funding for this work was provided by the National Science Foundation and USF. Professor Shengqian Ma led the USF team consisting of Qi Sun, Briana Aguila and David Rogers. Researchers from Soochow University, Southwest University of Science and Technology, and Tsinghua University in China also collaborated on the study.