Iron nanoparticles snatch uranium

Using wee balls of iron, scientists can catch radioactive fuel — hook, line and sinker.

In liquid, iron nanoparticles quickly lure and encase uranium, which researchers can then reel in with a simple magnet. The method, reported online February 17 in the Journal of the American Chemical Society, could be used to sop up radioactive spills or to fish for fuel for nuclear power plants.

The tiny particles have a core of pure iron and a shell of iron hydroxide. Negative charges in the shell attract positive charges in a water-soluble form of uranium, in this case uranyl nitrate. Once baited by a nanoparticle’s outer shell, the uranium gets sucked into the middle of the sphere. There, the iron shackles uranium with extra electrons, locking it into the globe’s nanostructure. The whole process occurs within minutes.

Environmental engineers Lan Ling and Wei-xian Zhang of Tongji University in Shanghai used high-powered microscopes to observe the capture. They also found that a simple magnet can then gather the particles and their radioactive booty. The researchers estimate that for every gram of iron, they can collect 2.4 grams of uranium.

The method could prove useful in responding to events such as the 2011 Fukushima Daiichi nuclear disaster, in which radioactive material spilled into the ocean after a tsunami slammed into Japan. The particles could also harvest uranium that is naturally present in seawater. The oceans contain about 4.5 billion metric tons of uranium (at very low concentrations). That amount of uranium could fuel current global nuclear power plants for thousands of years.