Iron nanoparticles could lead to more effectives carbon tetrachloride cleanup

Researchers at Pacific Northwest National Laboratory, the University of Minnesota and Oregon Health and Science University discovered that not all iron nanoparticles are created equal. Some, in fact, may be especially useful for cleaning up groundwater contaminated with carbon tetrachloride. In the past, carbon tetrachloride was used for various purposes by industry and government. Today, it is found in the soil and groundwater at sites around the country. Exposure to high levels of this chemical can damage the liver, kidneys and nervous system.

“Nanoparticles could find use in remediating deep inaccessible groundwater plumes, where other remediation technologies cannot be used cost-effectively,” said James Amonette, PNNL senior research scientist.

When carbon tetrachloride reacts with iron particles, the carbon tetrachloride breaks apart. Some of the products that can be produced are harmful, such as chloroform. Others are completely benign, such as water. The researchers’ challenge was to figure out how to tip the balance of this reaction to the safest possible products.

The research team characterized iron nanoparticles from a wide variety of sources. They discovered that one type of iron nanoparticle in particular produced much less chloroform than the other particles.

Then, the team determined the specific properties of this type of nanoparticle to understand why carbon tetrachloride followed the more benign reaction path. The team characterized the particles using x-ray diffraction and x-ray photoelectron spectroscopy in DOE’s Environmental Molecular Sciences Laboratory. At OHSU, the researchers performed electrochemical studies using an electrode designed especially for nanoparticles.

Based on the results of this fundamental research, the team believes they have identified the key contributors to chloroform formation. This new information could be used to help select and design iron nanoparticles for future carbon tetrachloride remediation efforts.