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Press Release
Eco-Friendly Pyrotechnics
Fireworks pollute—nitrogen-rich compounds now pave
the way for ecological alternatives
Contact: Thomas M.
Klapötke, Ludwig-Maximilians-Universität München (Germany)
Registered journalists may download the original article here:
“Green”
Pyrotechnics: A Chemists´ Challenge
You know it is chemistry when it stinks and goes boom—and
entrances us. “No other application in the field of chemistry has such
a positive association for the general population as fireworks,” says
Thomas Klapötke (University of Munich, Germany). “However, pyrotechnical
applications are significant polluters of the environment.” In the journal
Angewandte Chemie, Klapötke and his co-author Georg Steinhauser
(TU Vienna, Austria) give an overview of how nitrogen-rich compounds and
other new strategies could help to limit the danger to the environment.
In addition to fireworks, the field of pyrotechnics includes
applications like airbags, signal flares, propellants and charges for civil
and military purposes, and the production of nanoporous metal foams for
catalysis, hydrogen storage, and insulation.
Pyrotechnical materials contain an oxidizer and a reducing
agent; depending on the application, binding material, propellant charges,
coloring agents and smoke- and sound-producing agents can be added. When
a firework or other pyrotechnic is set off, it releases a whole cocktail
of poisons damaging to humans and the environment: heavy metals like lead,
barium and chromium, chlorates, dioxins, smoke and particulates, carbon
monoxide, and nitrogen and sulfur oxides. “For a long time, the consequences
of this were not considered,” says Klapötke, “in the mean time scientists
have been working on more environmentally friendly alternatives.” As usual,
the main stumbling block is price pressure because the new products must
compete with the established ones. Klapötke says, “Lawmakers and other
promoters must intercede to address this.”
“Modern developments in pyrotechnics are aimed at the
use of nitrogen-rich compounds,” according to Klapötke. In contrast to
conventional energetic substances, these do not draw their energy from
the oxidation of the carbon backbone, but from their high heats of formation,
which are released upon their decomposition. Interesting candidates include
derivatives of tetrazoles, five-membered rings made of four nitrogen and
one carbon atom, as well as tetrazines, six-membered rings made of four
nitrogen and two carbon atoms. Aminotetrazole salts with the nontoxic metals
lithium, sodium, potassium, rubidium and cesium result in red, orange,
violet, purple, and pink colored flames. The trouble is with the color
green. Intensive research is being carried out in search of barium-free
green-burning salts based on copper compounds.
The class of nitrogen-rich pyrotechnics does not offer
only environmentally friendly combustion products; they often offer better
color quality and intensity than conventional mixtures. Nitrogen-rich propellants
demonstrate improved performance and burn smoke free.
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