Washington, Jan 27 (IANS) Researchers have designed a novel material that targets and traps cesium, a radioactive ion in nuclear waste, and not other harmless ions like sodium.
The team was inspired by the Venus flytrap — a carnivorous plant that catches and digests animal prey, mostly insects.

The Northwestern University researchers found it to be extremely successful in removing cesium, found in nuclear waste but very difficult to clean up, from a sodium-heavy solution. The solution had concentrations similar to those in real liquid nuclear waste.

It is, in fact, cesium itself that triggers a structural change in the material, causing it to snap shut its pores, or windows, and trap the cesium ions within.

The synthetic material, made from layers of a gallium, sulphur and antimony compound, successfully segregates the total quantum of cesium ions from the solution while ignoring all the sodium ions.

“Ideally we want to concentrate the radioactive material so it can be dealt with properly and the non-radioactive water thrown away,” said Mercouri G. Kanatzidis, professor of chemistry at the Weinberg College of Arts and Sciences and senior study author.

“A new class of materials that takes advantage of the flytrap mechanism could lead to a much-needed breakthrough in nuclear waste remediation,” he said.

Capturing only cesium from vast amounts of liquid nuclear waste is like looking for a needle in a haystack, Kanatzidis said.

The waste has a much higher concentration of sodium compared to cesium, with ratios as great as 1,000-to-1. This difficult-to-achieve selectivity is why currently there is no good solution for cesium removal, said a Northwestern release.

The Northwestern material is porous with its atoms arranged in an open and layered framework structure with many windows to promote rapid ion exchange.

The results are published online in Nature Chemistry.