Peroxy Acetyl Nitrates is a secondary pollutant present in Photo chemical Smog. It is a lachrymatory substance. It is thermally unstable and decomposes into peroxy ethanoyl radicals and nitrogen dioxide gas. It is an oxidant and more stable than ozone.
Health effect :
At lower Concentrations :
It is a powerful respiratory and eye irritants, toxic in nature.
At higher Concentrations :
Cause extensive damage to vegetation, causing skin cancer.
Production Of PAN :
They are formed by the photochemical reaction between hydrocarbons, nitrogen oxides and light. It occurs in two steps
Step I :
Unburnt hydrocarbons undergo oxidation to give aldehydes, ketones and di carbonyl compounds, which creates peroxyacyl radicals.
Hydrocarbons + O2 + Light ----------------> Ch3 - C (=O) - O - O*
ie,
CH3CHO + OH- -------------> CH3CHO* + H2O
CH3CO* + O2 ----------------> CH3COOO*
Step II :
Peroxyacyl radicals combine with nitrogen dioxide to form peroxyacyl nitrates.
CH3 - C(=O) - O - O* + NO2 ----------------> CH3 - C(=O) - O - O - NO2
Sources :
1. It comes from the degradation of isoprene, hydrocarbon, acylation.
2. Blended gasoline with ethanol.
Environmental Effects :
1. Damages plants and art.
2. React Explosively.
3. Plays a very large role in photochemical smog.
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