Just two weeks after the Fukushima, Japan, nuclear crisis caused by the 9.0 earthquake-tsunami event on March 11, Tokyo water officials found 210 becquerels of radioactive iodine-131 per liter in the city’s drinking water.
Although levels up to 300 becquerels per liter are considered safe for adult consumption, anything over 100 becquerels is a risk, particularly for the young. The human body is incapable of distinguishing between radioactive iodide and non-radioactive iodide, which are chemically identical. The danger is comes from radioactive iodide accumulating in the thyroid gland, which can eventually lead to cancer.
Two weeks after that, on April 13, researchers at North Carolina State University, Raleigh, announced a new way to remove radioactive materials from drinking water, using forest byproducts and crustacean shells.
The NCSU material is a combination of hemicellulose, which is present (along with cellulose) in almost all plant cell walls, and chitosan, a polysaccharide derived from chitin. Chitin is widely present in the natural world, such as in the exoskeletons of insects. The NCSU process produces chitosan from crustacean shells that have been crushed into a powder.
The resulting substance binds iodide in water and traps it. The iodide can then be properly disposed of without risk to humans or the environment, explained Joel Pawlak, NCSU associate professor of forest biomaterials.
Pawlak said his material, which forms a solid foam and operates like a sponge when submerged in water, is also well suited for use in other disaster and emergency situations where water treatment or desalination is needed and there is no infrastructure power to operate municipal water systems.
“We think that the material will work well in survival situations where a simple tea bag or in-line filter can be used to remove salt from water to provide a personal drinking water supply,” Pawlak told Homeland1.
Pawlak has yet to field test the material, but he hopes to soon in Japan and is currently in contact with officials there.
“The biggest challenge that I foresee is the very small concentrations of radioactive elements dissolved in the water, which presents a challenge for any absorbent material,” he said.
“We have tested it with potassium iodide, and it works very similar to desalination applications,” he said, “so it can potentially be used to help safeguard water from radioactive elements dissolved in water.”
Pawlak also said the material is effective at removing heavy metals from water. “We can treat water contaminated with metals such as lead, mercury and arsenic.”
Finally, since the material is a hydrogel, it can be used in hazmat applications as an absorbent.