(263d) Oxidized Organic Compounds Formed from Chlorine-Initiated Oxidation of Toluene
AIChE Annual Meeting
2017
2017 Annual Meeting
Environmental Division
Atmospheric Chemistry and Physics I
Tuesday, October 31, 2017 - 8:51am to 9:08am
Toluene-OH oxidation has been studied in the past, and it has been difficult to form highly oxidized SOA in environmental chamber experiments. In the work reported here we achieved SOA oxidation states as high as 0.24 using Cl-initiated photo-oxidation reactions, which occur at a faster timescale than OH-initiated reactions. The SOA oxidation states were inferred from mass spectra measured by an Aerosol Chemical Speciation Monitor (ACSM) and a High Resolution Aerosol Mass Spectrometer (HR-AMS) and were consistently higher than those reported previously. The addition of NOx resulted in a higher organic aerosol oxidation state. Overall, our results indicate that toluene-Cl reaction under both low and high NOx conditions can yield highly oxidized organic aerosol and that this reaction pathway has the ability to alter SOA formation in the atmosphere.
Figure 1: Panel A shows major gas-phase products from toluene-Cl and toluene-OH pathways as measured by the HR-Tof-CIMS; Panel B shows common gas-phase products from both pathways as measured by the HR-Tof-CIMS; Panel C shows uncorrected organic aerosol formation as observed from the HR-AMS. Panels A, B and C all represent data obtained from low NOx-toluene-Cl system. The thick black line represents additional injection of chlorine during the experiment.