Over the last decade, the percentage of electronic waste occupying our landfills has grown quickly and has increased concerns about the toxicity of consumer electronics.  

According to R & D Magazine, Researchers Jean-Claude Bonzongo, associate professor of environmental engineering at University of Florida College of Engineering and  Kirk Ziegler, a UF associate professor of chemical engineering, are looking for ways to minimize environmental hazards associated with a material likely to play an important role in the manufacture of these goods in the future. The results of their most recent studies are published in Nanotoxicology.

Carbon nanotubes are being used in touch screens and to make smaller, more efficient transistors. If 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 there is still some concern.

"Depending on how the nanotubes are used, they can be toxic, exhibiting properties similar to asbestos in laboratory mice," Bonzongo.

The UF team is investigating toxicity associated with aqueous solutions of carbon nanotubes that would be used in certain manufacturing processes.

"At the nanoscale, electron interactions between atoms are restricted, and that creates some of the desirable traits like the high conductivity that manufacturers want to take advantage of with carbon nanotubes," Ziegler said.

This task can be difficult however, as carbon nanotubes have to be treated to keep them dispersed and available for electron interactions that make them good conductors.

"Some of the surfactants, or solutions, are toxic on their own," Bonzongo said. "And others become toxic in the presence of carbon nanotubes."

Bozongo and Zeigler are focusing their investigations on solutions that become hazardous when mixed with the carbon nanotubes. Their most recent results indicate that toxicity can be reduced by controlling the ratio of liquid to particulate.

A cost-effective means of unbundling nanotubes is one of the last problems for manufacturers to solve before they can mass-produce the technology. Current processes used for laboratory prototypes, including mechanical homogenization or centrifugal sifting, would be too expensive for manufacturing consumer electronics, so liquid suspension agents may be the way to go.

Bozongo said, "We want to get ahead of it and make sure that the progress is sustainable—in terms of the environment and human health."