Cloud Condensation Nuclei (CCN) Activity of Black Carbon Mixed with Low Aqueous Solubility Organics

KANISHK GOHIL, Reese Barrett, Dewansh Rastogi, Chun-Ning Mao, Akua Asa-Awuku, University of Maryland College Park

     Abstract Number: 541
     Working Group: Carbonaceous Aerosol

Abstract
Black Carbon (BC) is the second most important anthropogenic emission in the atmosphere. BC is produced from the incomplete combustion of fossil fuels and biomass. BC molecular composition and morphology vary depending on the source and BC combines with other organic and inorganic species present in the atmosphere. BC accounts for large uncertainties in the net aerosol indirect effect. BC is inherently insoluble in water and hydrophobic but is known to display water uptake behavior either due to its wettable nature or due to other species that are mixed with BC. Past studies show the application of Kohler theory and Frenkel-Halsey-Hill (FHH) adsorption theory for the analysis of pure and coated epoflex and regal BC and the characterization of BC CCN activity. In this work, we used vulcan BC to study its interaction with insoluble organics and CCN activity analysis. We used BC mixtures with low water solubility aromatic acids (phthalic acid, isophthalic acid, and terephthalic acid) in this work. We compared the CCN activity of BC-aromatic acid mixtures with pure BC using three different CCN models - traditional Kohler theory, FHH adsorption theory, and hybrid activity model. Analysis revealed that the CCN activity of pure BC enhances more than twice when aromatic acids are mixed with it. Furthermore, the CCN activity of BC mixed with aromatic acids showed a trend similar to pure aromatic acids. In addition to CCN measurements, we performed transmission electron microscopy (TEM) imaging of pure and mixed BC particles. Results show a size-dependent trend relative to whether pure BC, pure aromatic acid, or a mixture would constitute the aerosol population.