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Sometimes smaller is better
This high-resolution transmission electron microscopy image of a metallic iron nanoparticle shows the nature of its 'protecting' shell. The chemistry of the shell appears to be crucial to the nanoparticle's ability to react with carbon tetrachloride to produce
A research team from the Pacific Northwest National Laboratory, Oregon Health and Science University, University of Minnesota and the University of Idaho is studying the ability of nanoscale iron particles to reduce carbon tetrachloride, a common groundwater contaminant. In the past, carbon tetrachloride was a common component in refrigerants, industrial degreasers and pesticides.
This chemical is now an environmental contaminant, and according to the U.S. Environmental Protection Agency, carbon etrachloride can cause liver, kidney and central nervous system damage.
One remediation method for
contaminated groundwater uses
microsized iron particles that react
on contact with carbon tetrachloride.
However, the reaction often produces chloroform, another environmentally undesirable chemical.
The research team's studies indicate
that one type of nanosized iron particle can be more effective in reducing carbon tetrachloride in water than the microsized
particles while also minimizing the
production of chloroform.
"The use of nanosized particles
of iron for cleaning up contaminants in groundwater, soil and sediments
is an exciting new technology that
contributes to a general enthusiasm about nanotechnology," said Don Baer, the project's principal investigator from PNNL.
The researchers examined two iron
nanoparticles, one produced by the
hydrogen reduction of an iron oxide
(FeH2) and the other produced by a
solution synthesis (FeBH) method. The FeH2 particles had a shell made of iron oxide, and the FeBH had a shell that included boron oxide as well as iron oxide. The research study involved both the characterization of the particles and
examination of their reactivity. The team determined that FeH2 produced lower quantities of chloroform in comparison to FeBH or micron-sized particles of iron.
This study suggests that nanosized
iron particles with the right chemistry
may be the better ingredient for
new technologies to clean up carbon
tetrachloride in contaminated
groundwater sites around the country.