Speaker
Ella Ivanova
(New Jersey Institute of Technology)
Description
Atmospheric soot is a major air pollutant and a powerful warming agent. Nanoparticles comprising soot are branched fractal aggregates of near-spherical carbon monomers with a diameter of 10-40 nanometers. When exposed to condensable vapors, either at the combustion source or in the atmosphere, soot aggregates undergo morphological transformations, such as collapsing into globules[1-3]. The compaction of atmospheric soot can significantly alter its impacts on health and climate. This work mainly focuses on the solvation force due to condensate present on the soot aggregate.
The solvation forces depend on the properties of both condensate and solid surface. Individual soot monomers are made of amorphous and graphitic carbon. However, in modeling studies, these structures are often simplified to the form of a graphitic sphere. Our goal is to evaluate the validity of this simplification when modeling the soot restructuring process. In this study, we compare the interaction of carbon surfaces made of atomistically ordered (graphitic) and disordered (amorphous) structures with benzene molecules. Benzene is used as a surrogate for polycyclic aromatic hydrocarbons (PAHs), which are produced in the flame and can condense on soot aggregates, inducing restructuring[1].
On a nanoscale, the condensed liquid meniscus in the junction between monomers acts like a filled pore, creating a suction effect with negative capillary pressure. This amplifies effective stress within soot aggregates, influencing compaction and restructuring kinetics. We used Monte Carlo simulations in the grand canonical ensemble (GCMC) to calculate benzene adsorption isotherms in carbon pores and Molecular Dynamics simulations to calculate the solvation forces. Analysis of the simulation data indicates that the ordering effects near the graphitic surface result in noticeable differences in adsorption isotherms and solvation forces compared to amorphous surfaces[4]. Therefore, the choice of surface structure may impact forces and, hence, the restructuring of fractal soot aggregates.
Primary author
Ella Ivanova
(New Jersey Institute of Technology)
Co-authors
Alexei Khalizov
(Department of Chemistry and Environmental Science, New Jersey Institute of Technology, 323 Dr. Martin Luther King Jr. Blvd, Newark, NJ 07102, USA)
Prof.
Gennady Gor
(Princeton University, NJIT)
