Effects of volatile coatings and coating removal mechanisms on the morphology of graphitic soot

Bambha, Ray P.; Dansson, Mark A.; Schrader, Paul E.; Michelsen, Hope A.

doi:10.1016/j.carbon.2013.04.070

Cited by 41 publications

(67 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this report we present results of experiments focused on determining the effects of coatings of oleic acid on the morphology of combustion-generated mature soot particles [51] and on the magnitude and temporal response of LII signal from these particles [75]. Our results demonstrate that, for oleic-acid coatings, the dendritic soot particles become more compact when the coating is applied.…”

Section: Introductionmentioning

confidence: 75%

“…At fractal dimensions above 2 the absorption cross section is predicted to increase with fractal dimension [65]. Over the range of fractal dimension change induced by coatings (e. [51]), however, the calculated dependence of the absorption cross section on fractal dimension is not strong [65,67,68].…”

Section: Introductionmentioning

confidence: 98%

“…Numerous studies have shown that this aggregate morphology can become substantially compressed when the particles are coated with oxygenated hydrocarbons [48,[51][52][53][54][55][56][57][58][59][60][61] or sulfuric acid [21,56,[62][63][64]. This morphology restructuring may persist even when the coating is removed in a thermodenuder [51,53,55,56,60,63,64].…”

Section: Introductionmentioning

confidence: 99%

“…Mature uncoated soot aggregates have a dendritic, branched-chain morphology described by a fractal dimension of ~1.7-1.9 [40][41][42][43][44][45][46][47][48][49][50][51]. Numerous studies have shown that this aggregate morphology can become substantially compressed when the particles are coated with oxygenated hydrocarbons [48,[51][52][53][54][55][56][57][58][59][60][61] or sulfuric acid [21,56,[62][63][64].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

Bambha¹,

Dansson²,

Schrader³

et al. 2013

View full text Add to dashboard Cite

We have measured time-resolved laser-induced incandescence (LII) from combustion-generated mature soot extracted from a burner and (1) coated with oleic acid or (2) coated with oleic acid and then thermally denuded using a thermodenuder. The soot samples were size selected using a differential mobility analyser and characterized with a scanning mobility particle sizer, centrifugal particle mass analyser, and transmission electron microscope. The results demonstrate a strong influence of coatings particle morphology and on the magnitude and temporal evolution of the LII signal. For coated particles higher laser fluences are required to reach LII signal levels comparable to those of uncoated particles. This effect is predominantly attributable to the additional energy needed to vaporize the coating while heating the particle. LII signals are higher and signal decay rates are significantly slower for thermally denuded particles relative to coated or uncoated particles, particularly at low and intermediate laser fluences. 4 ACKNOWLEDGMENTSWe thank Daniel Strong for the rendition of the experimental setup shown in Fig. 1. We are very grateful to Chris Sorensen for his sage advice on fractal analysis. We also appreciate Alexei Khalizov's insightful comments about soot restructuring and Jeff Headrick's assistance with the TEM image analysis.

show abstract

Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

Bambha¹,

Dansson²,

Schrader³

et al. 2013

View full text Add to dashboard Cite

show abstract

“…However, in the lower temperature range, below 500 • C, they found a minor effect on soot fragmentation. Bambha et al [26] noticed only a small effect of thermodenuding at 410 • C (transit time of~34 s) on the morphology of soot during the removal of oleic acid coating. In another study, Slowik et al [64] did not observe any measurable change in the structure of soot when fresh soot (generated at ∅ = 2.1 and 3.5) was thermodenuded at 200 • C. Our results of the negligible or minor restructuring of thermodenuded soot particles are in agreement with these previous studies suggesting that these results are robust and reproducible.…”

Section: Resultsmentioning

confidence: 99%

Effect of Thermodenuding on the Structure of Nascent Flame Soot Aggregates

et al. 2017

View full text Add to dashboard Cite

Abstract:The optical properties (absorption and scattering) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with materials that can condense on a freshly emitted (nascent) soot particle 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 the absorption and scattering coefficients 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 structure of the pre-existing soot core is left unaltered, despite the potential oxidation of the core at elevated temperatures. In this study, we investigated the validity of the last assumption, by studying the effect of thermodenuding on the morphology of nascent soot. To this end, we analyzed 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.

show abstract

An unexpected restructuring of combustion soot aggregates by subnanometer coatings of polycyclic aromatic hydrocarbons

Chen

Fan

Shaltout

et al. 2016

Geophysical Research Letters

View full text Add to dashboard Cite

We investigated the effect of thin polycyclic aromatic hydrocarbon (PAH) coatings on the structure of soot aggregates. Soot aerosol from an inverted diffusion burner was size classified, thermally denuded, coated with six different PAHs, and then characterized using scanning electron microscopy, light scattering, and mass‐mobility measurements. Contrary to our expectation, significant restructuring was observed in the presence of subnanometer layers of pyrene, fluoranthene, and phenanthrene. These PAHs remained in subcooled liquid state in thin films, whereby the liquid layer acted as a lubricant, reducing the force required to initiate the restructuring. Thin layers of PAH of higher melting temperatures (perylene, anthracene, and triphenylene) presumably remained solid because these chemicals induced lesser structural changes. Our results suggest that some of the intrinsic PAH generated during incomplete combustion may induce significant restructuring of soot aggregates, even when present in small quantities, altering the properties and atmospheric impacts of combustion aerosols.

show abstract

Effects of volatile coatings and coating removal mechanisms on the morphology of graphitic soot

Cited by 41 publications

References 48 publications

Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

Effect of Thermodenuding on the Structure of Nascent Flame Soot Aggregates

An unexpected restructuring of combustion soot aggregates by subnanometer coatings of polycyclic aromatic hydrocarbons

Contact Info

Product

Resources

About