Aircraft engine particulate matter: Macro- micro- and nanostructure by HRTEM and chemistry by XPS

Carbonaceous particulate emissions from jet aircraft are a significant source of emissions from airports near urban areas. Physical structure and surface chemistry are relevant towards assessing impacts of combustion-produced soot upon the environment and assessing health impacts. In this report high-resolution electron microscopy (HRTEM) and X-ray photoelectron (XPS) data are presented for particulate emissions from a CFM-56-3 engine aboard a DC-9 aircraft, fueled by JP-8. Engine power levels were varied from 4% to 100%. Soot aggregate macrostructure, microstructure and nanostructure are discussed with respect to combustion conditions. Ultrafine particle size distributions at idle and near full power conditions are highlighted by HRTEM and compare favorably to reported scanning mobility particle sizer (SMPS) measurements. Particle composition, as inferred from the XPS ratio for sp2/sp3 carbon bonding is compared to results from thermo-optical evaluation of organic and elemental carbon analysis at selected powers with excellent agreement. Across engine power levels, these ultra-fine particles appear to be remnants of oxidized larger aggregates.