Mechanistic Insights into NO3 Oxidation of Furfural from Chamber Study
RAPHAEL MAYORGA, Kunpeng Chen, Nilofar Raeofy, Michael Lum, Bradley Ries, Roya Bahreini, Ying-Hsuan Lin, Haofei Zhang,
University of California, Riverside Abstract Number: 720
Working Group: Aerosol Chemistry
AbstractHeterocyclic volatile organic compounds (VOCs) are substantially emitted from biomass burning and may represent a significant source of secondary organic aerosol (SOA). Furfural is a heterocyclic VOC that represents a significant portion of these emissions. Despite its relevance, there have been very few experimental studies to uncover the major products and elucidate the chemical mechanism involved in the NO3 oxidation of furfural. In this study, we carried out experiments in a 10 m3 smog chamber to investigate the gas- and particle-phase mechanisms involved in the NO3 oxidation of furfural. The SOA yield from furfural + NO3 was ~0.02. The chemical composition of the SOA from NO3 oxidation of furfural was characterized using a suite of online and offline instrumentation. We propose a mechanism to explain the major products of this system and incorporated this into a chemical box model to compare with laboratory measurements. Previous studies have suggested that initial NO3 attack of furfural should proceed via addition to the double bond rather than by H-abstraction from the aldehyde group. However, some of the identified products from furfural + NO3 SOA are unlikely to form from a NO3 addition-initiated pathway, because they retain their aromatic backbone which would be lost through an NO3 addition pathway. The discrepancy may indicate that the NO3 H-abstraction pathway is more important than previously assumed. Overall, this study will expand the mechanistic understanding of the NO3 oxidation of furfural and will also help to improve future gas- and particle-phase mechanisms of furfural oxidation.