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At a time when the world is worried about the disastrous impact of waste plastic bags which take hundreds of years to disintegrate, it is Nanotechnology that could hold the key to dealing with this problem effectively. Researchers at the University of Adelaide, Australia, have developed a process for turning waste plastic bags into a high-tech nanomaterial.

Photo courtesy: marineinsight.com

The international advocacy group Ocean Crusaders has estimated that shoppers worldwide consume approximately 500 billion single-use plastic bags per year. This, according to the group, translates to "a million bags every minute across the globe, or 150 bags a year for every person on earth," and the numbers are rising.

About one lakh marine creatures, besides one million sea birds, are killed every year due to plastic entanglement. The problem stands compounded as it takes between 20 to 1,000 years for a plastic bag to break into smaller pieces.

While environmentalists are crusading for a ban on the use of hazardous plastic bags and urging people not to use them, researchers across the world are trying to address the problem through technological intervention.

At the University of Adelaide, the Nanotech Research Group has found that nanotechnology offers innovative solutions to transform non-biodegradable plastic grocery bags into 'carbon nanotube membranes'. These highly sophisticated and expensive materials have a variety of potential advanced applications including filtration, sensing, energy storage and a range of biomedical innovations.

"Non-biodegradable plastic bags are a serious menace to natural ecosystems and present a problem in terms of disposal," says Professor Dusan Losic, ARC Future Fellow and Research Professor of Nanotechnology in the University's School of Chemical Engineering.

"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 (1/10,000 the diameter of a human hair). They are the strongest and stiffest materials yet discovered- hundreds of times stronger than steel but six times lighter- and their unique mechanical, electrical, thermal and transport properties present exciting opportunities for research and development. They are already used in a variety of industries including in electronics, sports equipment, long-lasting batteries, sensing devices and wind turbines.

The University of Adelaide's Nanotech Research Group has 'grown' the carbon nanotubes onto nanoporous alumina membranes. They used pieces of grocery plastic bags which were vaporized in a furnace to produce carbon layers that line the pores in the membrane to make the tiny cylinders (the carbon nanotubes). The idea was conceived and carried out by PhD student Tariq Altalhi.

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

The huge potential market for carbon nanotubes hinges on the industry's ability to produce large quantities more cheaply and uniformly. Current synthesis methods usually involve complex processes and equipment, and most companies on 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 is also catalyst and solvent free, which means the plastic waste can be used without generating poisonous compounds.

Thus, technological intervention, coupled with a conscious reduction in the use of plastic bags can go a long way in dealing with the hazardous pollution caused by plastic carry-bags.

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