Jan 30, 2003
Nanotechnology could save the ozone layer
Whilst experimenting with nanospheres and perfluorodecalin, a liquid used in the production of synthetic blood, researchers at Germany's University of Ulm have stumbled across a phenomenon that could ultimately help remove ozone-harming chemicals from the atmosphere. The perfluorodecalin, against all expectations, was taken up by a water-based suspension of 60 nm diameter polystyrene particles.
The scientists believe that this occurred because nanoscopic perfluorodecalin droplets became encapsulated by self-assembled polystyrene nanospheres. Perfluorodecalin has very similar properties to chlorofluorocarbons (CFCs), the inert liquids that are known to destroy the Earth's protective ozone layer. And the Ulm team reckons that aerosol particle-carrying water droplets or ice crystals in clouds may be able to collect up chlorofluorocarbons in the same way, eventually returning them harmlessly to Earth as rain, hail or snow.
"I realized that I had developed a useful model system for the simulation of microphysical processes in the stratosphere," Andrei Sommer of the University of Ulm told nanotechweb.org. "In particular, for [simulating] the very complicated interplay between cloud droplets, nanoscopic aerosols emitted by man-made and natural sources, and chlorofluorocarbons - the principal ozone killers."
The solid aerosols that arise from urban and industrial sources, for example petrol and diesel particles, are roughly the same size as the polystyrene nanospheres used in this experiment.
"Nanoscale aerosols - which are also accused of suppressing rain and reducing the amount of sun reaching the Earth's surface - could in fact be helpful in reducing the stratospheric concentrations of ozone killers," added Sommer.
Sommer says that if tests confirm the predictions from the simple model system, the result could be a practical strategy to stop, or possibly even repair, one of the two potentially most destructive global problems caused by mankind. He reckons scientists could use space technology to carry large amounts of specially designed non-toxic nanoscale particles into the heart of the ozone hole.
In the short term, Sommer says it's worth optimizing the properties of such nanoscale particles - for example, aerosol size, chemical composition and solubility - while reducing the cost. Then it's a case of encouraging international space agencies to begin airborne experiments.
Back on Earth, meanwhile, the perfluorodecalin-based nanosphere suspension research could also have applications in nanopatterning and biofunctionalization techniques for biomaterials.
The scientists reported their work in Nano Letters.
About the author
Liz Kalaugher is editor of nanotechweb.org.