AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Advanced Molecular Speciation of Aircraft Engine Soot by Nano Desorption Electrospray Ionization Mass Spectrometry
JEREMY CAIN, Alexander Laskin, Julia Laskin, Edwin Corporan, David Blunck, William Roquemore, Air Force Research Laboratory/Propulsion Directorate
Abstract Number: 408 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Aircraft are the major source of black carbon in the upper troposphere and lower stratosphere. Aircraft particulate matter (PM) may impact the atmospheric environment through alteration of cloud forming processes and heterogeneous kinetics. As alternative fuels are explored to supplement the current fuel feedstock, it is important to assess the environmental impact of PM emissions relevant to these fuels. Soot particles from an Allison T63-A-700 turboshaft engine were deposited on aluminum foil inside an inertial cascade impactor and subsequently analyzed by nano-desorption electrospray ionization mass spectrometry (nano-DESI MS). The engine was operated at three power settings: low-speed idle, intermediate and cruise. Six fuels were tested: a JP-8, Fischer-Tropsch (F-T) and four alternative fuel surrogates (n-dodecane blends). Micro-FTIR spectroscopy results in a parallel investigation showed that aliphatic C-H and C-O groups are present in significant quantities. Advanced molecular speciation of those functionalities is performed here in both positive and negative modes for two solvents (acetonitrile and acetonitrile/toluene) over a mass range m/z = 150-900. Comparisons for this data set are made among particle size, fuel type and solvent. Additional comparisons are made for soot produced with a flat flame burner combusting a simple gaseous fuel (C$_2H$_4).