Bromide Alternatives newsletter tells more about what's
being done to replace this fumigant.
Coconut Carbon Can Trap a Used FumigantBy
Bits of activated carbon made from crushed and superheated coconut
shells can capture methyl bromide left over from fumigating crops at
packinghouses or other facilities. The fumigant kills insects that can
damage fruits, nuts, grains, and other commodities.
The activated carbon, housed in a steel container, trapped up to 95
percent of the methyl bromide in air vented to it in studies led by
entomologist James G. Leesch. He's with USDA's
Service in Fresno, Calif. The researchers used carbon granules
crushed to about the size of pea gravel.
The Fresno research will offer packinghouse managers and others the
first proven, practical method for keeping methyl bromide out of the
stratosphere. U.S. production of methyl bromide is scheduled to be
eliminated in 2001 because it is thought to damage the earth's
protective ozone layer.
The idea of using activated carbon to trap methyl bromide is not
new. But the new system also recycles activated carbon and yields a
useful chemical by-product. Leesch is testing the technology under a
cooperative research and development agreement between ARS and GFK
Consulting, Ltd., San Clemente, Calif., and Great Lakes Chemical
Corp., West Lafayette, Ind.
Earlier, ARS and GFK Consulting scientists found that, for trapping
methyl bromide, use, coconut-shell-carbon is superior to peat or
bituminous coal carbons. The scientists have tested the activated
carbon in conditions typical of the air-tight fumigation chambers.
Heating the spent activated carbon--with nitrogen, steam or
air--reactivates it for re-use and also drives off the trapped methyl
bromide. Further heating breaks down the methyl bromide into carbon
dioxide, water and hydrogen bromide that can be converted into a
compound suitable for making fire retardants and other chemicals.
Last fall, researchers completed preliminary pilot tests of a
prototype carbon-filled container at a California fig-packing plant.
They plan new experiments this spring at a portside facility.
Scientific contact: James G. Leesch, ARS Horticultural Crops
Research Laboratory, 2021 S. Peach Ave., Fresno, CA 93727. Phone (209)
453-3090, fax (209) 453-3088, email@example.com.