Characterization of aircraft engine soot: unique properties and cloud impact

International audienceAircraft engine soot collected at the outlet of a D30KU combustor is comprehensively characterized by numerical experimental techniques: TEM, EDS, AFM, FTIR, GC-MS, ion and liquid chromatography and gravimetry. Physical properties (morphology, microstructure, particle size, surface area, porosity) and chemical properties (elemental composition, water soluble/insoluble organic and inorganic fraction, surface functional groups, and volatility) are examined. The water uptake by engine soot is analyzed in a wide range of the relative humidity from 0.01 to 100% and temperatures from 233K to 295K. Engine soot exhibits unique features and especially a high hydrophilicity (20ML of adsorbed water at 240K) and an heterogeneity of its composition. Comparison with laboratory–made kerosene flame soot indicates that engine soot particles separates into two fractions: an hydrophobic main fraction which contains a reduced amount of sulfur and an hydrophilic fraction of impurities with large amounts of iron, oxygen, sulfur and potassium. These results allows us to estimate the environmental conditions able to develop aircraft engine soot indirect effects with respect to ice nucleation modes proposed for contrail and cirrus formation. Our finding of two fractions in engine soot leads us to suggest that the main fraction of aircraft – generated soot may initiate a sulfur-independent heterogeneous nucleation mode in the UT while the fraction of impurities is responsible for contrail formation

Microstructure and chemical composition of particles from small-scale gas flaring

Among globally relevant combustion sources, such as diesel emission and biomass burning, gas flaring remains the most uncertain. In this study, small-scale turbulent gas flaring was used to characterize particulate emissions produced under different operating conditions, such as various burner diameters and exit velocities. The composition of the fuel was also varied by modifying the perce

Ship particulate pollutants: Characterization in terms of environmental implication

International audienceA major aspect of monitoring the atmosphere is the quantification of man-made pollution and their interactions with the environment. Key physico-chemical characteristics of diesel exhaust particulates of sea-going ship emissions are presented with respect to morphology, microstructure, and chemical composition. Heavy fuel oil (HFO)-derived particles exhibit extremely complex chemistry. They demonstrate three distinct morphological structures with different chemical composition, namely soot, char and mineral/ash. The composition analysis investigates the content of environmentally-dangerous pollutants: metals, inorganic/mineral species, and soluble, volatile organic and ionic compounds. It is found that hazardous constituents from HFO combustion, such as transitional and alkali earth metals (V, Ni, Ca, Fe) and their soluble or insoluble chemical forms (sulfides, sulfates, oxides, carbides), are released together with particles into the atmosphere. The water soluble fraction, more than 27 wt%, is dominated by sulfates and calcium cations. They cause the high hygroscopicity of ship exhaust particles and their possible ability to act as cloud nuclei in humid marine environment