title: Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.
abstract: The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts.
authors.affiliation: Laboratory of Internal Combustion Engines, ‡Laboratory of Analytical Chemistry, and ∥Electron Microscopy Center, Empa Material Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Anthi
authors.initials: A
authors.lastname: Liati
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Brem
authors.forename: Lukas
authors.initials: L
authors.lastname: Durdina
authors.forename: Melanie
authors.initials: M
authors.lastname: Vögtli
authors.forename: Yadira Arroyo Rojas
authors.initials: YA
authors.lastname: Dasilva
authors.forename: Panayotis Dimopoulos
authors.initials: PD
authors.lastname: Eggenschwiler
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
mesh_terms: D000401:Aircraft / Q000706:statistics & numerical data*; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D053260:Soot / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D052638:Particulate Matter; D053260:Soot; D001335:Vehicle Emissions