Iron nanoparticles may reduce the cost of Superfund site cleanup by 75%

[satya]

http://www.csmonitor.com/2005/0210/p14s01-sten.html

The nanoparticles are particularly useful because of their size - a single human hair is 500 to 5,000 times as wide. At that scale, they can move through microscopic flow channels in soil and rock, reaching and destroying groundwater pollutants that larger particles cannot.

But the ultra-small size of iron nanoparticles alone is not enough to neutralize carbon tetrachloride; the chemistry is crucial. For example, when Tratnyek's team compared two leading types of particles, only one converted carbon tetrachloride to a mixture of relatively harmless product consisting of iron oxide with a magnetite shell high in sulfur. "This type of nanoparticle is now commercially available," says Tratnyek. (The other type of particle, coated with oxidized boron, created chloroform, a toxic and persistent contaminant.)

Other researchers are using nanoparticles containing palladium to convert toxic organic chemicals into harmless products. The palladium enables the iron to react with organic contaminants much faster than other types of iron nanoparticles, says Dr. Zhang.

When air-conditioner manufacturer Trane tested these nanoparticles at its Trenton, N.J., plant in 2001, they reduced the toxic organic solvent trichloroethylene, or TCE, in nearby well water by about 96 percent after 12 hours. More recently, field tests have been performed at several sites including a GlaxoSmithKline pharmaceutical facility in North Carolina.