3 Feb (NucNet): A team of scientists from Japan and the US say they may have discovered a way to remove radioactive caesium from the millions of litres of contaminated water being held at Japan’s Fukushima-Daiichi nuclear power station following the 2011 accident.
The team’s discovery stemmed from their work with lignin, a component of plant cell walls that is a hugely abundant by-product of pulp and paper production.
Yuichiro Otsuka, a researcher at the Forestry and Forest Products Research Institute in Tsukuba, Japan, and Tomonori Sonoki, professor of biochemistry and molecular biology at Hirosaki University in Japan, have been working with scientists from Virginia Tech in Blacksburg, Virginia, on ways to use waste lignin to produce more useful “platform chemicals” that can be used as precursors for the production of biofuels and biopolymers.
Through a bacterial fermentation of lignin waste compounds, the team was able to produce a unique molecule known as PDC, which can be combined with other molecules, or polymerised, into a variety of useful bioplastic compounds. The team determined the process for making large amounts of PDC from several types of lignin from pulp mills.
Although the targeted PDC molecule was intended as a platform chemical for biopolymer production, a surprising finding by the team led to a discovery that may help clean up radioactive caesium.
“Caesium is a unique compound known as an alkali metal,” said Barry Goodell, professor of sustainable biomaterials in Virginia Tech’s College of Natural Resources and Environment. “Metals like this can be removed from solutions if appropriate binding compounds can be identified, but finding an appropriate compound for the binding of caesium has been very difficult. The Japanese have been desperate to find an alkali metal binding compound that is specific to caesium.”
Because of the chemical structure of PDC, the team surmised that it might also be able to bind certain alkali metals. In the lab, when the PDC compound was tested on a nonradioactive isotope of caesium, the scientists discovered that PDC is especially good at both binding to caesium and pulling it out of a solution in a manner so that it could be readily collected.
When tests of the PDC were done with mixtures of other metal salts such as sodium chloride, the common table salt that is also the major salt in seawater, caesium was selectively bound by the PDC, allowing it to be pulled out of the solution for selective disposal.
“This could be a finding of major importance for the cleanup of the Fukushima-Daiichi reactor disaster,” a statement on Virginia Tech’s website said.
Japanese researchers are now exploring how the PDC compound can be further scaled up and how it can be applied to wastewater in Japan contaminated with radioactive caesium.
Details are online: www.vtnews.vt.edu/articles/2015/01/012815-cnre-nuclearcleanup.html
