Oxidation characteristics of airborne carbon nanoparticles by NO2

Abstract The oxidation characteristics of airborne carbon nanoparticles were investigated at various temperatures and NO 2 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 NO 2 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 NO 2 concentrations and reaction temperatures increased, the surface oxidation rate of carbon aerosol particles increased. For NO 2 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 NO 2 and O 2 gases was 65.9 kJ/mol, which is smaller than that for only NO 2 gas.