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.
Author: Thomas M. Klapötke, Ludwig-Maximilians-Universität München (Germany), http://www.chemie.uni-muenchen.de/ac/klapoetke/?menu=adress
Title: “Green” Pyrotechnics: A Chemists´ Challenge
Angewandte Chemie International Edition, doi: 10.1002/anie.200704510
Thomas M. Klapötke | Angewandte Chemie
Nonstop Tranport of Cargo in Nanomachines
20.11.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik
Researchers find social cultures in chimpanzees
20.11.2018 | Universität Leipzig
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Physics and Astronomy