Broken bulbs

Compact Fluorescent Lamps (CFLs) might cut down on household energy use, but there's a catch. Each lamp contains a small amount of mercury, a neurotoxin that can be released as vapour when a bulb is broken.

Now though, engineers at Brown University have discovered a nanomaterial that can absorb the mercury emitted from broken compact fluorescent lamps. And using it, they have created a mercury-capturing lining that can be attached to the inside of CFL packaging.

The packaging can be placed over the area where a bulb has been broken to absorb the mercury vapour emanating from the spill, or it can capture the mercury of a bulb broken in the box.

Robert Hurt, professor of engineering, and engineering student Natalie Johnson, developed the packaging along with other Brown engineering students and Steven Hamburg, associate professor of environmental studies.

They have also created a specially designed lining for plastic bags that soaks up the mercury left over from the CFL shards that are thrown away.

Both the mercury-absorbent packaging and the lined plastic bags can be safely discarded and recycled, the researchers say, alleviating concerns about contamination or other unwanted environmental consequences.

'It’s a complete management system to deal with a bulb broken in the home,' said Hurt, director of Brown’s Institute for Molecular and Nanoscale Innovation, which concentrates on the study and commercial application of nanotechnology.

Brown applied earlier this year for federal patents covering the mercury-absorption packaging and the absorbent material, and the university expects soon to begin discussions with companies on manufacturing the new technology.

The inspiration for the invention followed the discovery by Hurt, Johnson and fellow Brown researchers that a variant of a substance called nanoselenium - a form of selenium, a trace element used in diet supplements, among other products - absorbed virtually all the mercury emitted from a broken CFL.

In controlled experiments, the scientists found that 99 per cent of mercury vapour from a CFL broken in a sealed chamber was mopped up by nanoselenium in concentrations ranging from one to five milligrams.

The small amount needed to capture the mercury vapour bodes well for manufacturing mercury-absorbent cloths or lining at a low cost, Hurt said. The precise manufacturing costs will need to be determined by interested companies.

'More work is needed,' Hurt said, 'but this appears to be an inexpensive solution that can remove most of the safety concerns associated with CFL bulbs.'