Abstract
In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot and samples treated with various doses of O3 (g), HNO3 (g), and H2SO4 (g) are considered. Use of a literature method has allowed estimation of the enthalpy of immersion (Himm) for the soot samples based on contact angle observed. Contact angles for freshly collected soot were 65 - 110 deg. indicating its hydrophobic nature. Chemical processing of soot usually resulted in smaller contact angles and large increases in immersion enthalpy. However, the dose of ozone, nitric or sulfuric acid vapor required to achieve alteration of the soot surface appeared to be considerably larger than that expected to be experienced by authentic atmospheric samples during the soot particles lifetime. The most significant variability of soot contact angle was observed for the municipal bus exhaust samples, suggesting that combustion chemistry may significantly affect wetting behavior.
Highlights
IntroductionAtmospheric nanosphere soot (ns-soot) a.k.a. refractory black carbon (rBC) is formed during incomplete combustion
Atmospheric nanosphere soot a.k.a. refractory black carbon is formed during incomplete combustion
The range of contact angles observed is very similar to values Persiantseva et al reported in 2004 for several different soot samples [16]
Summary
Atmospheric nanosphere soot (ns-soot) a.k.a. refractory black carbon (rBC) is formed during incomplete combustion. Soot primary particles can be thought of as a mixture of sp hybridized carbon combined with highly strained graphitic sp layers required to conform to the spherical geometry of particles. Wei et al 12 water) we have become interested in understanding how atmospheric soot particles behave within or on the surface of micrometer-sized droplets of solvent. The essential question is whether soot particles fully immerse within liquid droplets, or remain on the surface of the liquid. Such details are crucial for developing a better understanding of the chemistry of the droplets, and for understanding the environmental impacts of light absorption by soot in Earth’s atmosphere
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