Relative rate constants for the heterogeneous reactions of OH, NO2 and NO radicals with polycyclic aromatic hydrocarbons adsorbed on carbonaceous particles. Part 1: PAHs adsorbed on 1–2 μm calibrated graphite particles

A discharge flow reactor was used to study the heterogeneous reactions of OH, NO2 and NO radicals with 11 polycyclic aromatic hydrocarbons (PAHs) adsorbed on 1–2 μm calibrated graphite particles. Graphite was chosen as a simple model of carbonaceous atmospheric particles. Relative kinetic information was obtained from the decays of particulate-PAH concentration vs. the time, measured using off-line gas chromatography coupled to mass spectrometry. Particulate-anthracene, -benzo(a)pyrene and -perylene are the most reactive with NO2, whereas all PAHs studied present similar reactivities with OH within uncertainties. The reactivity of NO under our experimental conditions could not be distinguished from the PAH desorption.