Modified carbon might hold the key to Fukushima cleanup Monday, 23 January 2017

A joint Russian-American team have found a way to extract radioactivity from water, a discovery which could help purify the contaminated water stored after the 2011 Fukushima nuclear accident.

The researchers from Rice University in Texas and Kazan Federal University (800 km east of Moscow) say their oxidatively modified carbon (OMC) material is inexpensive and highly efficient at absorbing radioactive metal cations, such as uranium, thorium and radium.

The material makes use of the porous nature of two specific sources of carbon. One is an inexpensive, coke-derived powder known as C-seal F, used by the oil industry as an additive to drilling fluids. The other is a naturally occurring, carbon-heavy mineral called shungite found mainly in Russia.

Treating the carbon particles with oxidising chemicals increased their surface areas and 'decorated' them with the oxygen molecules needed to adsorb the toxic metals. The particles were between 10 and 80 microns wide.

Rice University's James Tour said OMCs can also trap radioactive elements such as cesium and strontium which were released into the environment when the Fukushima nuclear plant in Japan melted down after an earthquake and tsunami.

While graphene oxide excelled at removing strontium, Tour said, the two types of OMC were better at extracting cesium, which he said has been the hardest element to remove from water stored at Fukushima. The OMC was also much easier and less expensive to synthesise and to use in a standard filtration system, he said.

“We know we can use graphene oxide to trap the light radioactive elements of relevance to the Fukushima cleanup, namely cesium and strontium,” he said.

“But in the second study, we learned we can move from graphene oxide, which remains more expensive and harder to make, to really cheap oxidised coke and related carbons to trap these elements.”

While other materials used for remediation of radioactive waste need to be stored with the waste they capture, carbon presents a distinct advantage, he said.

“Carbon that has captured the elements can be burned in a nuclear incinerator, leaving only a very small amount of radioactive ash that’s much easier to store,” Tour said.

[An electron microscope image of C-seal F, a source used to synthesise oxidatively modified carbon. Image: Kazan Federal University]