Researchers have announced they have successfully created cesium-absorbing radiation decontamination sponges using Prussian blue pigment, the same type of pigment used in famous Japanese Edo-era ukiyoe paintings.
Prussian blue pigment was used in the renowned "Thirty-six Views of Mount Fuji" works by Edo-era artist Katsushika Hokusai. While it has been known that Prussian blue is good at sticking to radioactive cesium, work to actually use the pigment had until now not progressed far.
The research group combined the pigment with the next-generation material "cellulose nano-fiber," which is made of the ingredients of paper, miniaturized to an exceedingly small size. This allowed the researchers to overcome the problem of the pigment being easily diluted by water. They then incorporated this combination into foam resin sponges.
In February last year they buried around 1.5 kilogram's worth of sponges, each a few cubic centimeters in size, in the soil of around 30 square meters of farmland in Namie, Fukushima Prefecture, near the disaster-stricken Fukushima No. 1 Nuclear Power Plant. They say that after four weeks, the cesium content of the soil was reduced by up to half of what it had been.
Until now, cesium absorbents have faced a problem of high production costs, but University of Tokyo professor Ichiro Sakata, who was part of the research group, says the new sponges' cost won't be "much different from that of a kitchen sponge." After absorbing materials, the sponges can be shrunk to about 1 percent of their original size, which would assist in reducing garbage volume, he says.
The research results were published in the Nov. 15 edition of the British academic journal Scientific Reports.