22 Nov 2016

22 Nov 2016

Review status: this preprint was under review for the journal AMT but the revision was not accepted.

Effect of thermodenuding on the structure of nascent flame soot aggregates

Janarjan Bhandari1, Swarup China1,a, Timothy Onasch2,3, Lindsay Wolff3, Andrew Lambe2,3, Paul Davidovits3, Eben Cross2, Adam Ahern4, Jason Olfert5, Manvendra Dubey6, and Claudio Mazzoleni1 Janarjan Bhandari et al.
  • 1Department of Physics and Atmospheric Sciences Program, Michigan Technological University, Houghton, MI, 49931, USA
  • 2Aerodyne Research Inc., Billerica, MA, 01821, USA
  • 3Chemistry Department, Boston College, Chestnut Hill, MA, 02467, USA
  • 4Centre for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, 15232, USA
  • 5Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, T6G 2G8, Canada
  • 6Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
  • anow at: Pacific Northwest National Laboratory, Richland, WA, 99354, USA

Abstract. The optical properties (light scattering and absorption) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with other material at the single particle level. For example, freshly emitted (nascent) soot particles can interact with other materials in the atmosphere, materials that can condense on soot and coat it. This coating can affect the soot optical properties by refracting light, or by changing the soot aggregate structure. A common approach to studying the effect of coating on soot optical properties is to measure absorption and scattering values in ambient air and then measure them again after removing the coating using a thermodenuder. In this approach, it is assumed that: 1) Most of the coating material is removed; 2) charred organic coating does not add to the refractory carbon; 3) oxidation of soot is negligible; and 4) the pre-existing core soot structure is left unaltered despite potential oxidation of the core at elevated temperature. In this study, we investigate the validity of the last assumption, by studying the effect of thermodenuding on the structure of nascent soot. To this end, we analyze the morphological properties of laboratory generated nascent soot, before and after thermodenuding. Our investigation shows that there is only minor restructuring of nascent soot by thermodenuding.

Janarjan Bhandari et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Janarjan Bhandari et al.

Janarjan Bhandari et al.


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Short summary
Soot particles emitted during the incomplete burning activities, absorb solar radiation and contribute to global warming. Light absorption by soot is also affected by its structure. To investigate whether the soot particle changes its structure or not, we used thermodenuding technique in which soot particles were passed through a heated tube (275 0C). Our study found only minor restructuring of soot suggesting no significant biases in absorption by the modification of soot structure alone.