Tuesday, April 24, 2012

Removing radioactivity

2 April 2012

Pellets capable of removing radioactive isotopes and heavy metals from milk, juice, and other beverages have been developed by chemists at Oklahoma State University. The material could be used to remove heavy metals from contaminated juices and other foodstuffs. And in emergency situations, such as the one that took place at the Fukushima nuclear plant in Japan last year, it could remove radioactive particles from liquids.

After the Fukushima accident, radioactive 89Sr was identified in milk as far afield as Hilo, Hawaii, according to EPA. Milk is the primary vector for human exposure to radioactive 89Sr, which tends to accumulate in bones and bone marrow and has been linked to bone cancer and leukemia.

Chemistry professor Allen Apblett and his team had been using nanoparticles to remove uranium from water, but after the events at Fukushima, they realized their technology could be made to take 89Sr out of liquids. He presented the work at the American Chemical Society national meeting in San Diego last week.

Pellets composed of nanoparticles can be used to decontaminate radioactive liquids, such as milk
Yellow pellets composed of CaWO4 nanoparticles can be used to remove radioactive 89Sr from liquids, such as milk.

The group’s technology uses calcium tungstate (CaWO4) nanoparticles, which swap Ca ions for Sr ions. The tungstate preferentially binds to Sr ions, instead of Ca ions, because of the former’s larger radius.

“It’s a chemical reaction that works its way from the outside of the particle to the core,” Apblett told C&EN.

The particles the group uses to make the pellets are 40–150 nm in diameter. The smaller the particle, Apblett said, the greater the total surface area, and therefore the higher the reactivity. The pellets are made by attaching the particles to alumina supports.

Apblett envisions loading the pellets into a porous cartridge, which consumers could put into a gallon of milk overnight. In the morning, they’d simply remove the cartridge from the decontaminated milk.

Apblett’s team has also prepared iron-based nanoparticles that can remove arsenic and other heavy metals from apple juice as well as liquids, such as baby formula, prepared with brown rice syrup. High arsenic concentration in these foodstuffs has been a recent concern.

“This work demonstrates how nanotechnology can be effectively and simply employed to solve a real-world problem,” comments Andrew R. Barron, a nanotechnology expert at Rice University. “More importantly, it is invisible as nanotechnology to the end user; it is just a product that works where no similar solution is possible.”

Source: American Chemical Society

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