Engineers keep a new technology clean

Particles in a liquid solution help keep single-wall carbon nanotubes dispersed.

 

by Donna Hesterman

The percentage of electronic waste occupying our landfills has grown at an alarming rate over the last decade, giving rise to concerns about the toxicity of components used in consumer electronics.

Researchers at the University of Florida are looking for ways to minimize environmental hazards associated with a material likely to play an increasingly important role in the manufacture of these goods in the future. The results of their most recent study are published in Nanotoxicology.

Carbon nanotubes are already being used in touch screens and to make smaller, more efficient transistors. And if current research to develop them for use in lithium ion batteries is successful, carbon nanotubes could become important technology for powering everything from smartphones to hybrid vehicles. But for all of the promise developers see in this emerging technology, there is also some concern.

“Depending on how the nanotubes are used, they can be toxic – exhibiting properties similar to asbestos in laboratory mice,” said Jean-Claude Bonzongo, associate professor of environmental engineering at UF’s College of Engineering. He is involved in a research collaboration with Kirk Ziegler, a UF associate professor of chemical engineering, to minimize this important material’s potential for harm.

Nanotubes tend to clump together so they have to be treated in some way to keep them dispersed and available for the electron interactions that make them good conductors. One way to do it is to mix them with an aqueous solution that acts as a detergent and separates the tangled bundles.

“But some surfactants, or solutions, are toxic or become toxic in the presence of carbon nanotubes.”

Their current research finds that toxicity can be reduced by controlling the ratio of liquid to particulate.

A cost-effective means of unbundling nanotubes remains one of the last hurdles for manufacturers to clear before they can employ the technology in mass-produced electronics.

Liquid suspension agents may be the way forward. Bonzongo said they want to get ahead of this emerging technology and make sure progress is environmentally sustainable.

Jean-Claude Bonzongo, bonzongo@ufl.edu

Kirk Ziegler, kziegler@che.ufl.edu