Kinetic behavior of non-volatile PAHs associated with urban aerosol

Abstract

Aerosol collected on quartz filters in an urban environment was exposed to light and dark conditions in two reactors, for 4 days and at a continuous low flow of ambient air. The decomposition of non-volatile PAHs was examined, assuming pseudo-first-order reaction kinetics. The half-lives of the originally detected PAH compounds were established for the prevailing experimental conditions. The ambient air passing through the boxes, devoid of new aerosol, constantly supplied the reactors with exogenic oxidants. The half-lives of the PAHs studied in the present experiments in the photo reactor, exhibited approximately a 10% decrease in their lifetime when compared with those obtained from the dark reactor. Oxidants formed by light activation on the collected aerosol, or photo dissociation, is the probable explanation. The half-life values for all the studied PAHs, agreed with literature values only in the cases that the substrate of these laboratory experiments was silica or diesel exhaust particles.