Understanding the Difference in Oxidative Properties between Flame and Diesel Soot Nanoparticles:  The Role of Metals

The purpose of this paper is to address the differences observed in the oxidative kinetics between flame and diesel derived soots. In particular, it has been observed that flame soot has a significantly higher activation energy for oxidation than does diesel soot. The hypothesis tested in this paper...

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Bibliographic Details
Published in:Environmental science & technology 2005-06, Vol.39 (11), p.4021-4026
Main Authors: Kim, S. H, Fletcher, R. A, Zachariah, M. R
Format: Article
Language:English
Subjects:
Air Pollutants - chemistry
Applied sciences
Atmospheric pollution
Carbon - analysis
Carbon - chemistry
Comparative analysis
Diesel engines
Diesel fuels
Exact sciences and technology
Gasoline - analysis
Hypotheses
Incineration
Kinetics
Lubricating oils
Mass Spectrometry
Metals
Metals - chemistry
Oxidation
Oxidation-Reduction
Particle Size
Pollutants physicochemistry study: properties, effects, reactions, transport and distribution
Pollution
Temperature
Vehicle Emissions - analysis
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Summary:The purpose of this paper is to address the differences observed in the oxidative kinetics between flame and diesel derived soots. In particular, it has been observed that flame soot has a significantly higher activation energy for oxidation than does diesel soot. The hypothesis tested in this paper is that metals, possibly coming from lubricating oils, within diesel generated soot particles may be responsible for this effect. This is supported by the fact that addition of metal additives to diesel fuel is shown to have no effect on the activation energy of soot oxidation. The subject of this paper lies in testing the hypothesis by adding metal directly to a flame and extracting oxidation kinetics. Using a high temperature oxidation tandem differential mobility analyzer (HTO-TDMA) we extract particle size dependent kinetics for the oxidation of flame-derived soot doped with and without iron. We found that indeed addition of iron to a flame reduced the activation energy significantly from ∼162 ± 3 kJ/mol to ∼116 ± 3 kJ/mol, comparable with diesel engine generated soot with an activation energy ∼110 kJ/mol. These results are consistent with the idea that small quantities of metals during diesel combustion may play an important role in soot abatement.
ISSN:0013-936X
1520-5851
DOI:10.1021/es048828z