Soot
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Soot (
Soot causes various types of cancer and lung disease.[2]
Sources
Soot as an airborne contaminant in the environment has many different sources, all of which are results of some form of
The formation of soot depends strongly on the fuel composition.
Description
The Intergovernmental Panel on Climate Change (IPCC) adopted the description of soot particles given in the glossary of Charlson and Heintzenberg (1995), "Particles formed during the quenching of gases at the outer edge of flames of organic vapours, consisting predominantly of carbon, with lesser amounts of oxygen and hydrogen present as carboxyl and phenolic groups and exhibiting an imperfect graphitic structure".[7]
Formation of soot is a complex process, an evolution of matter in which a number of molecules undergo many chemical and physical reactions within a few milliseconds.
Soot formation mechanism
Many details of soot formation chemistry remain unanswered and controversial, but there have been a few agreements:[1]
- Soot begins with some precursors or building blocks.
- Nucleation of heavy molecules occurs to form particles.
- Surface growth of a particle proceeds by adsorption of gas phase molecules.
- Coagulation happens via reactive particle–particle collisions.
- Oxidationof the molecules and soot particles reduces soot formation.
Hazards
Soot, particularly diesel exhaust pollution, accounts for over one-quarter of the total hazardous pollution in the air.[3][12]
Among these
Long-term
Diesel
This serves as a plausible mechanistic link between the previously described association between particulate matter air pollution and increased cardiovascular morbidity and mortality.Soot also tends to form in chimneys in domestic houses possessing one or more fireplaces. If a large deposit collects in one, it can ignite and create a chimney fire. Regular cleaning by a chimney sweep should eliminate the problem.[16]
Soot modeling
Soot mechanism is difficult to model mathematically because of the large number of primary components of
First, empirical models use correlations of experimental data to predict trends in soot production. Empirical models are easy to implement and provide excellent correlations for a given set of operating conditions. However, empirical models cannot be used to investigate the underlying mechanisms of soot production. Therefore, these models are not flexible enough to handle changes in operating conditions. They are only useful for testing previously established designed experiments under specific conditions.[1]
Second, semi-empirical models solve rate equations that are calibrated using experimental data. Semi-empirical models reduce computational costs primarily by simplifying the chemistry in soot formation and oxidation. Semi-empirical models reduce the size of chemical mechanisms and use simpler molecules, such as acetylene as precursors.[1] Detailed theoretical models use extensive chemical mechanisms containing hundreds of
Finally, comprehensive models (detailed models) are usually expensive and slow to compute, as they are much more complex than empirical or semi-empirical models. Thanks to recent technological progress in computation, it has become more feasible to use detailed theoretical models and obtain more realistic results; however, further advancement of comprehensive theoretical models is limited by the accuracy of modeling of formation mechanisms.[1]
Additionally, phenomenological models have found wide use recently. Phenomenological soot models, which may be categorized as semi-empirical models, correlate empirically observed phenomena in a way that is consistent with the fundamental theory, but is not directly derived from the theory. These models use sub-models developed to describe the different processes (or phenomena) observed during the combustion process. Examples of sub-models of phenomenological empirical models include spray model, lift-off model, heat release model, ignition delay model, etc. These sub-models can be empirically developed from observation or by using basic physical and chemical relations. Phenomenological models are accurate for their relative simplicity. They are useful, especially when the accuracy of the model parameters is low. Unlike empirical models, phenomenological models are flexible enough to produce reasonable results when multiple operating conditions change.[1]
Applications
Historically soot was used in manufacturing artistic paints and shoe polish, as well as a blackener for Russia leather for boots. With the advent of the printing press it was used in the printing ink well into the 20th century.[17] In modern technical applications it is referred to as "carbon black".
See also
- Activated carbon
- Atmospheric particulate matter
- Bistre
- Black carbon
- Brimstone
- Carbon black
- Coal
- Colorant
- Creosote
- Diesel particulate matter
- Dust
- Fullerene
- Health effects of coal ash
- Health effects of wood smoke
- Indian ink
- Joss paper
- Open burning of waste
- Rolling coal
- Soot blower
References
- ^ .
- ^
- Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; Deangelo, B. J.; Flanner, M. G.; Ghan, S.; Kärcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G. (2013). "Bounding the role of black carbon in the climate system: A scientific assessment" (PDF). Journal of Geophysical Research: Atmospheres. 118 (11): 5380.
- Juliet Eilperin (2013-11-26). "Black carbon ranks as second-biggest human cause of global warming". The Washington Post. Retrieved 2013-12-04.
- ^ .
- ISBN 0-471-72018-6.
- S2CID 96742040.
- ISBN 0-13-332537-7.
- ISBN 0-471-95693-7.
- ^ Rundel, Ruthann, "Polycyclic Aromatic Hydrocarbons, Phthalates, and Phenols", in Indoor Air Quality Handbook, John Spengleer, Jonathan M. Samet, John F. McCarthy (eds), pp. 34.1-34.2, 2001
- ^ Rundel, Ruthann, "Polycyclic Aromatic Hydrocarbons, Phthalates, and Phenols", in Indoor Air Quality Handbook, John Spengleer, Jonathan M. Samet, John F. McCarthy (eds), pp. 34.18-34.21, 2001
- ^ "Soots (IARC Summary & Evaluation, Volume 35, 1985)". Inchem.org. 1998-04-20. Retrieved 2013-12-04.
- PMID 25196472.
- ^ "Health Concerns Associated with Excessive Idling". Nctcog.org. Archived from the original on 2014-01-16. Retrieved 2013-12-04.
- New England Journal of MedicineFebruary 1, 2007
- PMID 18952612.
- PMID 17446340.
- ^ "Gr8fires". gr8fires.co.uk. 2015-02-22.
- ^ Surmiński, Janusz, "Węglarstwo leśne – sadza i potaż", Sylwan vol. 154 (3), 2010, pp. 182−186 (pdf file: www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjD_-mOqOCCAxWzKEQIHc-7BIIQFnoECBcQAQ&url=https%3A%2F%2Fbibliotekanauki.pl%2Farticles%2F1009503.pdf&usg=AOvVaw0K6o-KjiJN4ULbJqxQdDNx&opi=89978449)
External links
- Encyclopedia Americana. 1920. .