Polycyclic Aromatic Hydrocarbons(PAHs) are organic chemicals having fused aromatic rings. A simple example of aromatic compound is Benzene. PAH can have 3, 4, 5, 6 or 7 benzene rings. There are more than 100 compounds listed under PAHs. Some examples of PAHs are:
3-rings: Anthracene, Phenanthrene4-rings: Chrysene
5-rings:Benzo[a]pyrene
7-rings:Coronene
The primary source of PAHs is incomplete combustion of carbon containing fuels such as wood, coal, diesel, tobacco etc. Some of the PAHs are markers for the source of pollution. For example Retene is primarily found
in the smoke from the forest fire.
in the smoke from the forest fire.Anthracene
These PAHs are pollutants and they are carcinogenic to humans.
There are different methods to analyze these pollutants in laboratory. Our laboratory use gas chromatography-mass spectrometry for this purpose. They are found in soil, water, snow, vegetation, air. That means they are everywhere. These pollutants move from where they were produced. Researches have shown that the presence of PAHs in the atmosphere of remote places of the earth-Arctic region. This shows PAHs undergo long range transport. So no matter who is responsible for the production of such deadly pollutants, their bad effect is divided everyone in the earth.
I will write more specific information about these pollutants in upcoming blogs. Please visit science to society.
I am not chemistry major hai!
ReplyDeletePAH's are pollutants?
May be true for earth,
please write about PAH's found in interstellar medium too.
nabin
My blog
Nabin,
ReplyDeleteI am not that familiar to PAHs in interstellar space. They are found there and they absorb IR and UV radiation. This is a matter of concern and interest to astrochemists and other researchers.
PAHs are found in Carbon rich circumstelar shells. Origin of interstellar is unknown. Various mechanisms have tried to explain it.
1) ion-molecule reactions or organometallic catalysis in the gas phase in cold molecular clouds
2) surface catalysis on interstellar grains
3) photochemical processes in interstellar ices
4) synthesis during the ejection phase of red giant.