Oxidation characteristics of airborne carbon nanoparticles by NO(2).

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.