Vol. 13, issue 06-07, article # 8

Abstract:

The results of investigation into photolysis and photonucleation of simple aldehydes, most typical of car exhausts and emissions of power plants, are generalized. It is shown how the secondary phototransformations of aldehydes (formaldehyde, acetaldehyde, and benzaldehyde) lead to formation of organic acids, peroxyl compounds, and aerosols as secondary pollutants. The application of experimental kinetic and analytical methods along with numerical simulation of phototransformation and photonucleation processes allowed us to study short-lived free radicals, gas products, and photoaerosols generated from the aldehydes. The data obtained in our studies along with the literature data allowed us to propose and validate physicochemical mechanism of the aldehyde photonucleation at the level of elementary stages from the primary event of photolysis to the gas-to-particle phase. This transition is followed by growth via adsorption of other species from air including aldehydes and accompanying water vapor, as well as other optically active compounds.