13 replies to this topic

[Gazza]

Personal visible spectroscopy is key to the search for green fireworks, not only figuratively but from the literal position of searching for environment friendly bangs and flashes.

Humanity's pyrotechnic fascination began more than two millennia past when it was discovered that saltpetre, potassium nitrate, could accelerate explosively the combustion of organic matter. Civil and military applications from entertaining displays at Olympic opening ceremonies, to pyrotechnics for safety, airbags, fire extinguishers, flares, and the synthesis of nanoporous foams (for catalysis, hydrogen storage, and insulation) and propellants, are now almost ubiquitous. With such widespread use, however, comes the potential for environmental harm.

Pyrotechnics is a vast industry - $2.6 billion annually in pyrotechnics and explosives. Current pyrotechnics involve the use of toxic metals. However, less noxious organic alternatives that can provide the requisite explosion and illumination are keenly sought.

Now, Georg Steinhauser of the Vienna University of Technology, Austria, and Thomas Klapötke of the Ludwig-Maximilian University of Munich, Germany, discuss nitrogen-containing compounds - energetic materials, such as the derivatives of tetrazoles and tetrazines - that could displace heavy metals in pyrotechnic compositions. They have found that a complete range of explosive colours is possible with the ironic exception of green, which usually requires barium salts.

"No other application in the field of chemistry has such a positive association for the general population as fireworks," enthuses Klapötke, "However, pyrotechnic applications are significant polluters of the environment." Writing in the Wiley journal Angewandte Chemie, Klapötke and Steinhauser suggest that the development of unstable nitrogen-rich compounds and various other strategies could mitigate this problem.

Pyrotechnics require an oxidizer and a reducing agent and, depending on the application, a binding material, propellant charges, colouring agents and smoke- and sound-producing materials. This veritable chemical cocktail releases a whole slew of pollutants when deployed, releasing among other materials, 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," adds Klapötke, "in the meantime scientists have been working on more environmentally friendly alternatives."

The main obstacle to making green pyrotechnics is cost. Any new product must compete on price with the established market. Klapötke, however, suggests that "Lawmakers and other promoters must intercede to address this."

The next generation pyrotechnics will exploit the high heats of formation of nitrogen-rich compounds rather than drawing energy from the conventional oxidation of a carbon backbone. Such metastable or unstable compounds release their energy of formation as they decompose explosively without producing smoke.

Interesting candidates for pyrotechnic alternatives include the tetrazoles and their derivatives, these compounds contain a five-membered rings composed of four nitrogen and one carbon atom, as well as tetrazines, six-membered rings made of four nitrogen and two carbon atoms. For example, salts of aminotetrazole salts can be formed with non-toxic metal ions, such as lithium, sodium, potassium, rubidium and caesium to make red, orange, violet, purple, and pink flames. Only green is missing from the pyrotechnic palette but researchers are looking for barium-free green-burning salts based on copper compounds.

One aspect of the fireworks clean-up that remains is avoiding perchlorate as the oxidiser and chlorine source because of its toxicity. "A possible solution to this problem could be the introduction of metal nanoparticles into the pores of nanostructured metal oxides," the researchers suggest. This remains an important challenge for chemists.

The new class of nitrogen-rich pyrotechnics offers not only environmentally friendly combustion products but the colours are often richer and more intense, say the researchers. Soon we could see smokeless, poison free and far less-polluting fireworks filling the ceremonial night skies, just as long as they are green.

Related links:

• Angew Chen, 2008, in press
• Klapötke Page

Article by David Bradley


Article on environmentally-friendly fireworks, taken from www.spectroscopyNOW.com

Organic, green fireworks

[phildunford]

Very interesting and I'm all for new research on the subject.

However, it's a constant source of amazement to me that people believe that fireworks contribute in any meaningful way to 'pollution'.

Compaired to power generation or cars or almost anything else, the effect must be unmeasureable...

PS

Where can I get a couple of kilos of Caesium Aminotetrazole - lol - Cooperman??

Edited by phildunford, 23 April 2008 - 01:03 PM.

[rr22]

I can see the antis jumping all over this,
not only lethal and noisily anti social, but now bad for the "environment" utter B.S.
The crop of 3 headed babies in the Crystal palace area during the 1930's was pure coincidence.

[cooperman435]

Im on it lads! Give me a few days though!

[pyrotrev]

Typical academics - I read one of his research papers the other night, very clever guy, but somewhat out of touch with commercial realities I think. The last time I bought a caesium compound it cost £14 (+VAT ) for 25g trade, the same salt in rubidium would have been even more, it's a rare element and a bugger to separate from sodium and potassium I believe. What price a 100 shot cake with an NEQ of 2.4 Kg at that rate?

Edited by pyrotrev, 25 April 2008 - 01:02 PM.

[MDH]

Yeah. I was thinking a little bit about price too. Maybe they should simply limit the overruse of certian compounds.

It may be a little shallow of me to suggest but it seems like more and more lately fireworks are becoming a cute little scapegoat for everybody to abuse whenever they feel they must.

Edited by MDH, 25 April 2008 - 08:56 AM.

[pyrotrev]

I seem to remember the Swedish government doing a study on this, and when you averaged the toxic compounds in fireworks out over the country for one year it was quite insignificant, and that was on a metals basis. Of course the fact is that the 2 most toxic things in pyro compositions (soluble barium and Cr (VI)) will likely get converted to more benign compounds during the combustion.

[motco]

I happened into this forum while researching the truth about an allegation (apparently from the Environment Agency but I cannot confirm this) that the dioxin pollution from the Millennium firworks display was more in the few minutes that it ran for than from a municipal waste incinerator running for 100 years. I have no figures for a typical incinerator, but I had sort of assumed that fireworks these days were made to a standard that defined the pollution levels and that no developed country would allow levels of toxic pollution as implied in the EA statement.

Does anyone have any views or quotable sources on this please?

[Asteroid]

Aren't dioxins mostly from decomposing or burning plastics? I was also under the impression that proper incinerators emit very little dioxin pollution because of the total combustion at high temperatures within the furnace.
If you are correct then I would have thought there is little that can be done to stop this without totally changing pyrotechnics, besides, the high altitude of these alleged emissions would lend to them being dispersed vey quickly, with much entering the stratoshpere and being broken down by UVC light.

[Gazza]

Might aswell ban fireworks altogether! These annoying 'Health and Safety' killjoys.
What about the nitrogen oxides, sulpur oxides, polycyclic aromatic hydrocarbon (PAH's) being pumped out of automobile exhausts on a DAILY basis? Hang your head out of the car window on the M25 and take a deep breath- you see what I mean (cough, cough, cough).
Much of pyrotechnic smoke consists of metal particulates (oxides and sulphides) which eventually settle to the ground and become absorbed harmlessly into the soil and vegetation. The concentration of these particulates dispersed over a wide area must be very small indeed- neglible.

[motco]

Might aswell ban fireworks altogether! These annoying 'Health and Safety' killjoys.
What about the nitrogen oxides, sulpur oxides, polycyclic aromatic hydrocarbon (PAH's) being pumped out of automobile exhausts on a DAILY basis? Hang your head out of the car window on the M25 and take a deep breath- you see what I mean (cough, cough, cough).
Much of pyrotechnic smoke consists of metal particulates (oxides and sulphides) which eventually settle to the ground and become absorbed harmlessly into the soil and vegetation. The concentration of these particulates dispersed over a wide area must be very small indeed- neglible.

Actually my purpose is not to show fireworks in a bad light, but to refute this seemingly ridiculous statement regarding an industrial furnace that burns up to half a million tonnes of unclassified domestic waste, containing God knows what, a year. Central government seems hell bent on building hundreds of these things to burn waste that could well be composted or otherwise benignly decomposed. Their defence of the health worries is to trot out this assertion vis a vis the millennium display which, to my mind. makes no sense at all. I would like a manufacturer of fireworks to give quotable evidence that the allegation is nonsense so that those of us having incinerators (euphemistically called energy from waste) forced upon their localities can shoot down the daft statements like this and the one that garden barbeques are more polluting than incinerators.

[pyrotrev]

As I understand it, dioxins are the product of low temperature incomplete combustion of hydrocarbons; think of smouldering bonfires etc. At the temperatures that exist in firework flames such compounds are smashed down to basic C, CO, H2O and CO2, depending on the amount of oxygen available. Seems to me whoever made that report about the Millenium display (which one?) needs to be challenged.

[digger]

I believe polychlorinated dibenzodioxins (PCDDs) are the nasty ones. The are formed from the combustion of chlorinated plastics such as PVC and by inference I also assume Parlon. They can be formed as combustion gases cool through the 600C to 200C region (hence exhaust gas quenching from certain incinerators). So given that most colour comps have a high degree of chlorinated plastic it would appear at the very least there is a possibility of dioxin formation.

[crystal palace fireworks]

Very interesting and I'm all for new research on the subject.

However, it's a constant source of amazement to me that people believe that fireworks contribute in any meaningful way to 'pollution'.

Compaired to power generation or cars or almost anything else, the effect must be unmeasureable...

PS

Where can I get a couple of kilos of Caesium Aminotetrazole - lol - Cooperman??

Call me cynical.........to me this go`s to prove that the green lobby groups who influence governments are just wasting tax payers money to gain future tax revenue from any areas of industry that they can get there hands on!

I wonder if any of these research papers are worth the paper they are written on compared to its so-called meaningful content? or are these academics just writing nonsense to justify more research grants for there university departments at the expense of more important issues?

If anyone wants to be enlightened on the so-called effects of pollution on our environment and its relationship to global warming/pollution etc.....then may I suggest people read the stuff of Professor Philip Stott.

Please note.........I am no supporter of any political party (I hate politicians and what they stand for).