Seeking to scrub radioactive waste

A NOVEL material has been developed that is capable of absorbing double its weight in iodine before reuse, and according to researchers could aid in the cleanup of nuclear accidents.

The porous organic material was developed by a team of researchers in the US, who say that this is the first demonstration of iodine scrubbing from water. Radioactive iodine is a common byproduct of nuclear fission and a pollutant in disasters such as Japan’s Fukushima Daiichi meltdown in 2011.

Lead researcher, Chenfeng Ke of Dartmouth College in the US, said: “We have solved the stubborn scientific problem of making a porous material with high crystallinity that is also chemically stable in strong acidic or basic water.”

The material is described in the Journal of the American Chemical Society paper as a crystalline microporous hydrogen-bonded cross-linked organic framework. It is capable of reducing the concentration of iodine in water from 288 ppm to 18 ppm in 30 minutes. The research used non-radioactive iodine in salted water, but researchers say that it will also work in real-world conditions.

According to Ke, upon application to contaminated water the compound would initially float, then sink as it absorbs iodine and becomes heavier. Due to its elastic nature, it could then be collected and cleaned by solvent evacuation, before being reused while the radioactive elements are sent for storage. He hopes that through continued testing the material will prove to be effective against caesium and other radioactive contaminants associated with nuclear plants.

Ke said: “It would be ideal to scrub more radioactive species other than iodine – you would want to scrub all of the radioactive material in one go.

'We are not sure how efficient this process will be, but this is definitely the first step toward knowing its true potential.'

The authors created the porous material using a ‘soft stitching’ technique that involves chemically cross-linking molecular precursors that had been pre-organised into a crystalline state by hydrogen-bonding interactions.

“In the process of developing a material that combats environmental pollution, we also created a method that paves the way for a new class of porous organic materials.'

Journal of the American Chemical Society: http://doi.org/b8dz