Scientists Recycle Plastic Bags Into Carbon Nanotubes
September 25, 2013

Scientists Recycle Plastic Bags Into Carbon Nanotubes

Lee Rannals for – Your Universe Online

One man's waste plastic bags could be a high-tech's nanomaterial, according to a new study published in the journal Carbon.

Researchers at the University of Adelaide have developed a process for turning plastic bags like you get at the grocery store into "carbon nanotube membranes." This high-tech nanomaterial is a sophisticated and expensive material with a variety of potential applications, including filtration, sensing, energy storage and other biomedical innovations.

"Non-biodegradable plastic bags are a serious menace to natural ecosystems and present a problem in terms of disposal," Professor Dusan Losic, ARC Future Fellow and Research Professor of Nanotechnology in the University's School of Chemical Engineering, said in a press release. "Transforming these waste materials through 'nanotechnological recycling' provides a potential solution for minimizing environmental pollution at the same time as producing high-added value products."

Carbon nanotubes are tiny cylinders of carbon atoms, one nanometer in diameter, which is about one-ten-thousandth the diameter of a human hair. These nanotubes are hundreds of times stronger than steel but six times lighter. The material has unique mechanical, electrical, thermal and transport properties present, making it an exciting tool for researchers. Carbon nanotubes are already being used in industries such as electronics, sports equipment, long-lasting batteries, sensing devices and wind turbines.

Researchers grew the carbon nanotubes onto nanoporous alumina membranes using pieces of grocery bags, which were vaporized in a furnace to produce carbon layers that line the pores in the membranes.

"Initially we used ethanol to produce the carbon nanotubes," says Professor Losic. "But my student (Tariq Altalhi) had the idea that any carbon source should be useable."

The potential for carbon nanotubes hinges on the industry's ability to produce large quantities more cheaply and uniformly. Current synthesis methods involve complex processes and equipment, and most companies in the market measure production output in only several grams per day.

"In our laboratory, we've developed a new and simplified method of fabrication with controllable dimensions and shapes, and using a waste product as the carbon source," says Professor Losic.

The process used by the researchers is seen as a jumping point for a future where plastic waste can be used without generating poisonous compounds.

The University of Adelaide researchers are not the only scientists trying to make carbon nanotubes more affordable. Researchers at the Technische Universitaet Muenchen (TUM) have found a way to provide low-cost, industrial scale manufacturing of the material. They have even devised a way to use carbon nanotubes to make a gas sensor that could be integrated into food packaging to gauge freshness.