July 1st, 2008
Towards eco-friendly fireworks?
Many fireworks will be launched in July, at least in the U.S. and in France. A recent American Chemical Society’s Weekly PressPac briefly describes how chemists are developing environmentally friendlier compounds for fireworks (scroll to article #5 in the PressPac). Current ‘fireworks, flares and other so-called pyrotechnics commonly include potassium perchlorate to speed up the fuel-burning process.’ But perchlorate has been identified as a potential human health hazard causing thyroid damage. So ‘researchers recently developed new pyrotechnic formulas that replace perchlorate with nitrogen-rich materials or nitrocellulose that burn cleaner and produce less smoke.’ But read more…
You can see above some generic fireworks. (Credit: Courtesy of Wikimedia Commons, via this EurakAlert! page) As mentioned above, “scientists plan to replace potassium perchlorate, a harmful substance widely used in fireworks, with cleaner, less toxic materials.”
Let’s first look at why potassium perchlorate can be dangerous with the help of an article from Chemical & Engineering News (C&EN) (Volume 86, Number 26, Pages 14-18). “Over the years, perchlorate has become the oxidizer of choice for most pyrotechnic applications, supplanting less stable chlorate oxidants that were the cause of numerous deadly explosions. ‘Potassium perchlorate is the ideal oxygen donor to use in pyrotechnics in terms of safety, cost, and reproducibility,’ says John A. Conkling, a pyrotechnics expert and adjunct professor of chemistry at Washington College, in Chestertown, Md. Unfortunately, perchlorate has also been identified as a potential human health hazard. Studies suggest that it inhibits the thyroid’s ability to take up iodine from the bloodstream and can reduce the production of thyroid hormone. And because the anion is highly water soluble, it readily slips into groundwater.”
Robert G. Shortridge, a scientist in the Pyrotechnic Operations Branch at the Crane Division of the Naval Surface Warfare Center, and his colleagues “have been working to replace the perchlorate in colored signal flares. So far, they’ve had the most success with red signal flares that use strontium-based oxidants. Their perchlorate-free formulation is about to undergo safety testing, as well as tests in which the flares will be loaded into the signal hardware and subjected to the environmental rigors they would experience in service. “We intend to pass all of them while making the environment a little safer too,” Shortridge says of the tests.”
The C&EN article also warns us that coloring agents used during fireworks could be friendlier to the planet. “The other area in which pyrotechnics could improve from an environmental standpoint is their use of coloring agents. To achieve colored fireworks and flares, pyrotechnic makers employ metals or metal compounds that emit light in the visible spectrum. Red hues come from strontium, sodium glows yellow, barium burns green, and blues and greens come from copper. At one time, mercury and lead compounds were used as colorants, but they were phased out long ago. Ironically, the modern pyrotechnic components that could use some “greening” are the barium compounds that give fireworks and flares their green color.”
If you’re interested in pyrotechnics, you must read the very well documented — but long — C&EN article. However, if you have no time for this, “you should know that most experts think the level of pollution from shooting off fireworks outdoors a couple of times per year is actually pretty small.” So enjoy the Fourth of July and Bastille day fireworks without feeling too guilty. Please keep in mind that eco-friendly fireworks are not as cost-effective as conventional fireworks today.
Sources: American Chemical Society’s Weekly PressPac, June 25, 2008; Bethany Halford, Chemical & Engineering News, June 30, 2008 issue; and various websites
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