Researchers publish radioactive strontium stripping method

Researchers at Japan’s Okayama University have described a system for removing radioactive strontium from aqueous solution based on its adsorption onto a naturally-occurring insoluble metamorphic mineral.

Researcher Toshiro Ono and colleagues found that adsorption onto a column of hydroxyapatite removed about 90% of the dissolved beta-emitter, strontium 90. The researchers said they were hopeful that their technique could be useful for removing strontium 90 from wastewater as well as natural water in the environment.
Removal of strontium 90 currently requires a complicated extraction and purification process for analysis using various types of organic and inorganic adsorbents. Therefore few studies on strontium 90 release have been performed so far.

The Okayama team found that the adsorption of strontium 90 by on hydroxyapatite was not influenced by calcium ion concentrations of up to 1 mM – more than the 0.375-0.5 mM average concentration of calcium ions in natural water in Japan. And magnesium ions had little effect on the removal of strontium 90 over the entire concentration range that was tested.

Once the strontium 90 was adsorbed, the researchers stripped it from the column using a small amount of eluate. They were then able to use the regenerated column for a further round of separation. The concentrated strontium 90 could be dried and stored securely as solid waste, reducing the volume and cost of disposal space

Radioactive strontium 90, with a half-life of close to 30 years, was among a number of long half- life nuclides released following the infamous catastrophe at the Fukushima nuclear power plant in 2011.