Soot, the Black Smoke Air Pollutant
A soot is a black substance formed by combustion or separated from fuel during combustion, rising in fine particles, and adhering to the sides of the chimney or pipe conveying the smoke; especially : the fine powder consisting chiefly of carbon that colors smoke. Or, the fine black particles, chiefly composed of carbon, produced by incomplete combustion of coal, oil, wood, or other fuels.
Soot is theorized to be the second-largest cause of global warming.
Soot as an airborne contaminant in the environment has many different sources, all of which are results of some form of Pyrolysis. Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen (or any halogen). It involves simultaneous change of chemical composition and physical phase, and is irreversible.
They include soot from coal burning, internal combustion engines, power-plant boilers, hog-fuel boilers, ship boilers, central steam-hot boilers, waste incineration, local field burning, house fires, forest fires, fireplaces, and furnaces. These exterior sources also contribute to the indoor environment sources such as smoking of plant matter, cooking oil, oil lamps, candles, quartz/halogen bulbs with settled dust, fireplaces, exhaust emissions from vehicles, and defective furnaces.
Soot in very low concentrations is capable of darkening surfaces or making particle agglomerates, such as those from ventilation systems, appear black. Soot is the primary cause of "ghosting", the discoloration of walls or ceilings and flooring where they meet. It is generally responsible for the discoloration of the walls above baseboard electric heating units.
The formation of soot depends strongly on the fuel composition. The rank of sooting tendency of fuel components is: napthalenes - benzenes - aliphatics. However, the order of sooting tendecies of the aliphatics (alkanes, alkenes and alkynes) varied dramatically depend on the flame type. The difference between the sooting tendencies of aliphatics and aromatics is thought to result mainly from the different routes of formation.
Aliphatics appear to first form acetylene and polyacetylenes, which is a slow process, aromatics can form the soot both by this route and also by a more direct pathway involving ring condensation or polymerization reactions building on the existing aromatic structure.
Hazards
Particularly with diesel exhaust pollution, accounts for over one quarter of the total hazardous pollution in the air. Among these diesel emission components, particulate matter has been a serious concern for human health due to its direct and broad impact on the respiratory organs. In earlier times, health professionals associated PM 10 with chronic diseases, lung cancer, influenza, asthma and increased mortality rate. However, recent scientific studies suggest that these correlations be more closely linked with fine particles PM2,5, and ultra-fine particles.
Diesel exhaust (DE) gas is a major contributor to combustion - derived particulate matter air pollution. In human experimental studies using an exposure chamber setup. DE has been linked to acute vascular dysfunction and increased thrombus formation. 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 chimney fire. Regular cleaning by a chimney sweep should eliminate the problem.
The Mandala Research
The blue flame fire on the gas burner is the initial result of the mandala research with the cooking gas. The bottom of pots and kettles are inspected from soot which seemed to be clear from any char coloring.
Reference:
1. http://www.merriam-webster.com/dictionary/soot
2. https://en.wikipedia.org/wiki/Soot
