Oxidation characteristics of airborne carbon nanoparticles by NO2

Abstract

The oxidation characteristics of airborne carbon nanoparticles were investigated at various temperatures and NO2 concentrations. Airborne carbon nanoparticles were generated by spark-discharging method using nitrogen as a carrier gas. Monodisperse carbon particles classified using a differential mobility analyzer were introduced into a tube furnace with NO2 for oxidation reaction. The size distributions of oxidized carbon aerosol particles were measured using a scanning mobility particle spectrometer system which consisted of a differential mobility analyzer and a condensation particle counter. The result was that as NO2 concentrations and reaction temperatures increased, the surface oxidation rate of carbon aerosol particles increased. For NO2 gas, the activation energy of the oxidation reaction was approximately 76.3 kJ/mol. The activation energy of the oxidation reaction for the mixture of NO2 and O-2 gases was 65.9 kJ/mol, which is smaller than that for only NO2 gas. (C) 2008 Elsevier B.V. All rights reserved.