Citrate appears to control buckyball clumping but environmental conce...( Blacksburg Va. -- Fullerenes also fo...)

Blacksburg, Va. -- Fullerenes, also fondly known as buckyballs, are showing an ugly side. Since being discovered in 1985, the hollow carbon atoms have been adapted for nanotechnology and biomedical applications ranging from electronics to carriers of imaging materials.

It appears that the hydrophobic, or water hating, carbon molecules clump together in water, forming aggregates of thousands of molecules. And there are reports that these aggregates can be toxic to microorganisms and even fish, should they escape from processing into surface water and ground water.

Now researchers at Virginia Tech have demonstrated that this behavior can be changed by the addition of citric acid although the good news and bad news of this recent discovery has yet to be determined. They will report on their research to both environmental chemists and colloidal chemists at the American Chemical Society 235th national meeting in New Orleans on April 6 to 10, 2008.

Our group and other research groups worldwide are examining what makes these fullerene aggregates tick and how they form, said Peter Vikesland, associate professor of civil and environmental engineering at Virginia Tech. Once they clump, they dont settle out. People dont know why they remain suspended. And we dont really know how many molecules are in a clump. We use the term nC₆₀ where N means some number that is extremely large.

What Vikeslands group has done that is different and novel is, instead of mixing the molecules with water, they have added citric acid, a naturally occurring and readily available acid. The result is that instead of unstructured clumps, we get reproducible sphere-shaped aggregates, he said.

They discovered, for example, that in the presence of a little bit of acid, which emulates the environment in the case of an accidental release of fullerenes, the aggregates are similar to those formed in water alone. But when more acid is added,
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