Science Inventory

Yields and molecular composition of gas-phase and secondary organic aerosol from the photooxidation of the volatile consumer product benzyl alcohol: formation of highly oxygenated and hydroxy nitro-aromatic compounds

Citation:

Jaoui, M., K. Docherty, M. Lewandowski, AND T. Kleindienst. Yields and molecular composition of gas-phase and secondary organic aerosol from the photooxidation of the volatile consumer product benzyl alcohol: formation of highly oxygenated and hydroxy nitro-aromatic compounds. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, Germany, 23(8):4637–4661, (2023). https://doi.org/10.5194/acp-23-4637-2023

Impact/Purpose:

Atmospheric chemistry experiments for benzyl alcohol was conducted to measure SOA yields, concentrations of O3, gas phase and SOA organic compounds, and secondary air toxics and to identify potential tracers that could be used for source apportionment. Benzyl alcohol, an oxygenated VCP with high potential to form SOA and air toxics, was selected in this study. The results of this work will be used to (1) improve our understanding of atmospheric chemistry and processes, and pathways leading to ambient PM, (2) and inform chemical transport model and chemical mechanism development, and (3) identify harmful chemicals and prioritize them in toxicity and human health. These data and findings can be used by EPA program offices (OAQPS and OTAQ), and external collaborators (state/local air quality management districts, academic institutions) to inform management strategies.    

Description:

Recently, volatile chemical products (VCPs) have been increasingly recognized as important precursors for secondary organic aerosol (SOA) and ozone in urban areas. However, their atmospheric chemistry, physical transformation, and their impact on climate, environment and human health remain poorly understood. Here, the yields and chemical composition at the molecular level of gas and particle phase products originating from the photooxidation of one of these VCPs, benzyl alcohol (BnOH), is reported. The SOA was generated in the presence of seed aerosol from nebulized ammonium sulfate solution in a 14.5 m3 smog chamber operated in flow mode. More than 50 organic compounds containing nitrogen and/or up to seven oxygen atoms were identified by mass spectrometry. While a detailed non-targeted analysis has been made, our primary focus has been to examine highly oxygenated and nitro-aromatic compounds. The major components include ring-opening products with high oxygen to carbon ratio (e.g., malic acid, tartaric acids, arabic acid, trihydroxy-oxo-pentanoic acids, and pentaric acid), and ring-retaining products (e.g., benzaldehyde, benzoic acid, catechol, 3-nitrobenzyl alcohol, 4-nitrocatechol, 2-hydroxy-5-nitrobenzyl alcohol, 2-nitrophloroglucidol, 3,4-dihydroxy-5-nitrobenzyl alcohol). The presence of some of these products in the gas and particle phases simultaneously provides evidence of their gas/particle partitioning. These oxygenated oxidation products made dominant contributions to the SOA particle composition in both low and high NOx systems. Yields, organic mass to organic carbon ratio, and proposed reaction schemes for selected compounds are provided. The aerosol yield was 5.2% for BnOH/H2O2 at SOA concentration of 52.9 µg m-3 and ranged between 1.7-8.1 % for BnOH/NOx at SOA concentration of 40.0-119.5 µg m-3.

Record Details:

Record Type:DOCUMENT( JOURNAL/ PEER REVIEWED JOURNAL)
Product Published Date:04/19/2023
Record Last Revised:09/08/2023
OMB Category:Other
Record ID: 358904