Application of a FIGAERO ToF CIMS for on-line characterization of real-world fresh and aged particle emissions from buses. Issue 3 (4th March 2019)

• Record Type: Journal Article
• Authors: Le Breton, M.; Psichoudaki, M.; Hallquist, M.; Watne, Å. K.; Lutz, A.; Hallquist, Å. M.
• Is Part Of: Aerosol science and technology. Volume 53:Issue 3(2019)
• Page Start: 244
• Page End: 259
• Publication Date: 2019-03-04
• Subjects: Matti Maricq; Aerosols -- Periodicals; Aerosol Propellants -- Periodicals; Aerosols -- Periodicals; 660.294515
• DOI: 10.1080/02786826.2019.1566592
• Languages: English
• ISSNs: 0278-6826

Abstract

Abstract: On-line chemical characterization of real-world particle emissions from 13 transit buses was performed using a chemical ionization mass spectrometer (CIMS) equipped with a filter inlet for gases and aerosols (FIGAERO). In addition to the fresh emissions the emissions were artificially aged using a potential aerosol mass reactor (Go:PAM). The buses studied were running on different fuel types (diesel, compressed natural gas, and rapeseed methyl ester) and exhaust after-treatment systems (selective catalytic reduction (SCR), exhaust gas recirculation (EGR), and a three-way catalyst). When evaluating emissions from passing exhaust plumes using the FIGAERO ToF-CIMS, two technical features were highlighted from this work, the use of high mass calibrants and the factor enhancement method to be able to filter important compounds from mass spectra including hundreds of species. Here, acetate was used as the reagent ion to enable detection of highly oxygenated species in the exhaust particle emissions with potential high toxicity and/or secondary organic aerosol formation (SOA) potential. The acetate ionization scheme accounted for 4% to 46% of the total emitted particulate mass through identification of 61 species in the spectra. For aged emission the various fuel types provided overlapping species that could explain up to 19% of the aged emissions. This is hypothesized to come from the oxidation of engine lubrication oil, thus a common source for various fuels which was further supported by laboratory measurements. Specific markers from the SCR technology, such as urea oxidation products and further byproducts from hydrolysis were identified and attributed to reactions of isocyanic acid. Copyright © 2019 The Author(s). Published with license by Taylor & Francis Group, LLC