Iodine is removed from an aqueous solution by the addition of the novel microporous material, termed HCOF-1. Photos: Chenfeng Ke/Dartmouth College.
Iodine is removed from an aqueous solution by the addition of the novel microporous material, termed HCOF-1. Photos: Chenfeng Ke/Dartmouth College.

For the first time ever, researchers at Dartmouth College have developed a new material that can scrub radioactive iodine from water. This breakthrough could hold the key to cleaning radioactive waste in nuclear reactors and after nuclear accidents like the 2011 Fukushima disaster in Japan.

"There is simply no cost-effective way of removing radioactive iodine from water, but current methods of letting the ocean or rivers dilute the dangerous contaminant are just too risky," said Chenfeng Ke, assistant professor in the Department of Chemistry at Dartmouth College. "We are not sure how efficient this process will be, but this is definitely the first step toward knowing its true potential."

Radioactive iodine is a common by-product of nuclear fission and a common pollutant after nuclear disasters like the recent meltdown in Japan and the 1986 Chernobyl disaster. While removing iodine in the gas phase is relatively common, iodine had never been removed from water prior to the Dartmouth research.

"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," said Ke, the principal investigator of the research. "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."

In a paper in the Journal of the American Chemical Society, the researchers describe how they produced the new material by using sunlight to crosslink small organic molecules. This approach is different from the traditional production method of combining molecules in one pot.

The resultant microporous material could reduce concentrations of iodine from 288 parts per million (ppm) to 18 ppm within 30 minutes, and below 1 ppm after 24 hours. The crosslinking technique resulted in a breathable material that changed shape and adsorbed more than double its weight of iodine. The compound was also found to be elastic, making it reusable and potentially even more valuable for environmental clean-up.

According to Ke, the material can simply be added to contaminated water. Since it is lighter than water, the material floats on top to adsorb the iodine and then sinks as it becomes heavier. After taking on the iodine, the compound can be collected, cleaned and reused, while the radioactive elements are sent for storage.

The researchers tested the material on non-radioactive iodine in salted water, but say that it will also work in real-world conditions. Ke and his team hope that continued testing of the material will also demonstrate its effectiveness against cesium and other radioactive contaminants associated with nuclear plants.

"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," said Ke.

The researchers are also hopeful that the same technique can be used to create materials able to target other types of inorganic and organic pollutants, particularly antibiotics in water supplies, which can lead to the creation of super-resistant microorganisms.

This story is adapted from material from Dartmouth College, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.