Neutron diffraction study of water freezing on aircraft engine combustor soot

The study of the formation of condensation trails and cirrus clouds on aircraft emitted soot particles is important because of its possible effects on climate. In the present work we studied the freezing of water on aircraft engine combustor (AEC) soot particles under conditions of pressure and temp...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2011-01, Vol.13 (46), p.2729-2735
Main Authors: Tishkova, V, Demirdjian, B, Ferry, D, Johnson, M
Format: Article
Language:English
Subjects:
Aerospace engines
Aircraft
Aircraft engines
Chemical Physics
Chemistry
Condensed Matter
Exact sciences and technology
Freezing
General and physical chemistry
Materials Science
Neutron diffraction
Ocean, Atmosphere
Physics
Sciences of the Universe
Soot
Sulfates
Surface chemistry
Surface physical chemistry
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Summary:The study of the formation of condensation trails and cirrus clouds on aircraft emitted soot particles is important because of its possible effects on climate. In the present work we studied the freezing of water on aircraft engine combustor (AEC) soot particles under conditions of pressure and temperature similar to the upper troposphere. The microstructure of the AEC soot was found to be heterogeneous containing both primary particles of soot and metallic impurities (Fe, Cu, and Al). We also observed various surface functional groups such as oxygen-containing groups, including sulfate ions, that can act as active sites for water adsorption. Here we studied the formation of ice on the AEC soot particles by using neutron diffraction. We found that for low amount of adsorbed water, cooling even up to 215 K did not lead to the formation of hexagonal ice. Whereas, larger amount of adsorbed water led to the coexistence of liquid water (or amorphous ice) and hexagonal ice ( I h ); 60% of the adsorbed water was in the form of ice I h at 255 K. Annealing of the system led to the improvement of the crystal quality of hexagonal ice crystals as demonstrated from neutron diffraction. Water adsorbed on aircraft engine combustor soot can stay liquid/amorphous till 215 K or form hexagonal ice coexisting with liquid/amorphous water, depending on the number of monolayer (ML) adsorbed.
ISSN:1463-9076
1463-9084
DOI:10.1039/c1cp21109a