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Effective Density Characterization of Soot Agglomerates from Various Sources and Comparison to Aggregation Theory

Rissler, Jenny LU ; Messing, Maria LU ; Malik, Azhar LU ; Nilsson, Patrik LU ; Nordin, Erik LU ; Bohgard, Mats LU ; Sanati, Mehri LU and Pagels, Joakim LU (2013) In Aerosol Science and Technology 47(7). p.792-805
Abstract
Soot particle (black carbon) morphology is of dual interest, both from a health perspective and due to the influence of soot on the global climate. In this study, the mass-mobility relationships, and thus effective densities, of soot agglomerates from three types of soot emitting sources were determined in situ by combining a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). High-resolution transmission electron microscopy was also used. The soot sources were diesel engines, diffusion flame soot generators, and tapered candles, operated under varying conditions. The soot microstructure was found to be similar for all sources and settings tested, with a distance between the graphene layers of 3.7-3.8... (More)
Soot particle (black carbon) morphology is of dual interest, both from a health perspective and due to the influence of soot on the global climate. In this study, the mass-mobility relationships, and thus effective densities, of soot agglomerates from three types of soot emitting sources were determined in situ by combining a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). High-resolution transmission electron microscopy was also used. The soot sources were diesel engines, diffusion flame soot generators, and tapered candles, operated under varying conditions. The soot microstructure was found to be similar for all sources and settings tested, with a distance between the graphene layers of 3.7-3.8 angstrom. The particle specific surface area was found to vary from 100 to 260m(2)/g. The particle mass-mobility relationship could be described by a power law function with an average exponent of 2.3 (+/- 0.1) for sources with a volatile mass fraction <10% and primary particle sizes of 11-29nm. The diesel exhaust from a heavy duty engine at idling had a substantially higher volatile mass fraction and a higher mass-mobility exponent of 2.6. The mass-mobility exponent was essentially independent of the number of primary particles in the range covered (N-pp = 10-1000). Despite the similar exponents, the effective density varied substantially from source to source. Two parameters were found to alter the effective density: primary particle size and coating mass fraction. A correlation was found between primary particle size and mass-mobility relationship/effective density and an empirical expression relating these parameters is presented. The effects on the DMA-APM results of doubly charged particles and DMA agglomerate alignment were investigated and quantified. Finally, the dataset was compared to three theoretical approaches describing agglomerate particles' mass-mobility relationship. Copyright 2013 American Association for Aerosol Research (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Aerosol Science and Technology
volume
47
issue
7
pages
792 - 805
publisher
Taylor & Francis
external identifiers
  • wos:000321321500010
  • scopus:84879078735
ISSN
1521-7388
DOI
10.1080/02786826.2013.791381
project
MERGE
language
English
LU publication?
yes
id
6e8fbabe-3860-422c-abe5-703723a75d89 (old id 3979577)
alternative location
http://www.tandfonline.com/doi/pdf/10.1080/02786826.2013.791381
date added to LUP
2013-09-03 15:24:43
date last changed
2019-10-23 01:33:45
@article{6e8fbabe-3860-422c-abe5-703723a75d89,
  abstract     = {Soot particle (black carbon) morphology is of dual interest, both from a health perspective and due to the influence of soot on the global climate. In this study, the mass-mobility relationships, and thus effective densities, of soot agglomerates from three types of soot emitting sources were determined in situ by combining a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). High-resolution transmission electron microscopy was also used. The soot sources were diesel engines, diffusion flame soot generators, and tapered candles, operated under varying conditions. The soot microstructure was found to be similar for all sources and settings tested, with a distance between the graphene layers of 3.7-3.8 angstrom. The particle specific surface area was found to vary from 100 to 260m(2)/g. The particle mass-mobility relationship could be described by a power law function with an average exponent of 2.3 (+/- 0.1) for sources with a volatile mass fraction &lt;10% and primary particle sizes of 11-29nm. The diesel exhaust from a heavy duty engine at idling had a substantially higher volatile mass fraction and a higher mass-mobility exponent of 2.6. The mass-mobility exponent was essentially independent of the number of primary particles in the range covered (N-pp = 10-1000). Despite the similar exponents, the effective density varied substantially from source to source. Two parameters were found to alter the effective density: primary particle size and coating mass fraction. A correlation was found between primary particle size and mass-mobility relationship/effective density and an empirical expression relating these parameters is presented. The effects on the DMA-APM results of doubly charged particles and DMA agglomerate alignment were investigated and quantified. Finally, the dataset was compared to three theoretical approaches describing agglomerate particles' mass-mobility relationship. Copyright 2013 American Association for Aerosol Research},
  author       = {Rissler, Jenny and Messing, Maria and Malik, Azhar and Nilsson, Patrik and Nordin, Erik and Bohgard, Mats and Sanati, Mehri and Pagels, Joakim},
  issn         = {1521-7388},
  language     = {eng},
  number       = {7},
  pages        = {792--805},
  publisher    = {Taylor & Francis},
  series       = {Aerosol Science and Technology},
  title        = {Effective Density Characterization of Soot Agglomerates from Various Sources and Comparison to Aggregation Theory},
  url          = {http://dx.doi.org/10.1080/02786826.2013.791381},
  volume       = {47},
  year         = {2013},
}