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Cloud Condensation Nuclei Activation of Internally Mixed Black Carbon Particles
Shila Maskey, Ka Yan Chong, Arom Seo, Mikyung Park, Kwangyul Lee, Kihong Park
National Leading Research Laboratory (Aerosol Technology and Monitoring Laboratory), School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
- Cloud condensation nuclei (CCN) activation of coated black carbon was measured.
- High CCN activation was observed for sulfuric acid-coated black carbon.
- CCN activation increased with increasing volume fraction of coating species.
- Mixing method can control the CCN activation of mixed black carbon.
Cloud condensation nuclei (CCN) activation of black carbon (BC) particles coated with different amounts of inorganic (sulfuric acid) and organic (levoglucosan or succinic acid) compounds was investigated. An evaporation-condensation method was used to produce coated BC particles, and the volume fractions of coating species were measured using the tandem differential mobility analyzer method. Furthermore, the CCN activation of the coated BC particles was measured using a differential mobility analyzer-CCN counter method. Coating with both aforementioned compounds engendered the activation of the BC particles as CCN at a supersaturation of 0.5%. Sulfuric acid coating was associated with the highest CCN activation fraction (= CCN/condensation nuclei), followed by levoglucosan coating and then succinic acid coating; this indicates that the water solubility of the coating compounds played a crucial role in the CCN activation of the coated BC particles. In general, the CCN activation fraction of the coated BC particles increased with the volume fraction of the coating species, but the manner of increase differed with the coating compounds and generation method. A premixed solution method was also used to produce mixed BC particles, and among the coating compounds, sulfuric acid was associated with the highest CCN activation fraction. For a given volume fraction, sulfuric-acid-coated BC particles produced using the premixed solution method showed a higher CCN activation fraction compared with those obtained using the evaporation-condensation method, and this was due to the presence of residual water in the sulfuric-acid-coated BC particles produced using the premixed solution method.
TDMA; Water solubility; CCN activation fraction; Coating.