Nuclear power plants produce radioactive iodine as a waste material. These iodine isotopes are harmful to human health and can cause, e.g., thyroid cancer. Efficiently capturing iodide, iodate, and organoiodine species from liquid nuclear waste is, thus, important. Silver-impregnated zeolites, for example, are a promising capture material for iodide and organoiodine. However, their performance for the removal of iodate is insufficient.

Wooyong Um and colleagues, Pohang University of Science and Technology (POSTECH), Republic of Korea, have developed bismuth-functionalized graphene oxide (GO) for the removal of both iodide and iodate from radioactive wastewater. The team synthesized GO from natural graphite powder. Then they functionalized the GO by mixing it with Bi(NO₃)₃·5H₂O in water and sonicating the mixture. The product was removed by centrifugation and calcined at 70 °C under an argon atmosphere.

The prepared material was tested in sorption experiments using iodide and iodate solutions. The team found that roughly 90 % of the iodine was removed within five minutes, regardless of the iodine species. The removal efficiencies of the functionalized GO for iodide and iodate are significantly higher than those of silver-impregnated zeolites. According to the researchers, BiOI and Bi(IO₃)₃ are formed on the material’s surface upon iodide and iodate removal, respectively.

• Development of bismuth functionalized graphene oxide to remove radioactive iodine,
  Sangsoo Han, Wooyong Um, Wonseok Kim,
  Dalton Trans. 2018.
  https://doi.org/10.1039/c8dt03745k