SECONDARY AEROSOL FORMATION IN AN OXIDATION FLOW REACTOR - MASS SPECTROMETRY AND PARTICLE SIZE MEASUREMENTS

Secondary organic aerosol is formed from the atmospheric oxidation of gas-phase organic compounds and primary aerosol. Despite the danger that this class of particles constitutes for human health and climate, secondary aerosol studies are limited; how the principal emissions' sources contribute to the secondary organic aerosol formation is still unknown. This work analyses the formation of secondary organic aerosol from the oxidation of soot precursor nanoparticles generated by a premixed laminar ethylene-rich flame. Flame exhausted gases and particles are sent to an oxidation flow reactor to replicate the atmospheric conditions through which the secondary aerosol formation reactions occur. As an on-line measurement, the oxidized aerosol is sent to a scanning mobility particle sizer system to evaluate the particles' size distributions; as off-line measurement, the collected aerosol is analysed by the High Resolution - Time of Flight - Aerosol Mass Spectrometer for a chemical characterization. The secondary aerosol formed displays an increase in mean diameter at different oxidation conditions and reveals an enhancement factor with respect to primary aerosol.