AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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The Effect of Particle Physicochemical Properties on the Uptake of Semi-volatile and Intermediate-volatility Organic Molecules
YIMING QIN, Junfeng Wang, Yali Lei, Jianhuai Ye, Scot T. Martin, Harvard University
Abstract Number: 304 Working Group: Aerosol Chemistry
Abstract Semi-volatile and intermediate-volatility organic compounds (S/IVOCs) play an essential role in the production of atmospheric particulate matter (PM), its chemical aging, and composition changes in preexisting particles. Mass transfer of S/IVOCs to preexisting particles is known to be sensitive to the physicochemical of the particles yet the detail mechanisms remain poorly understood. To address this issue, we combine experimental observation and theoretical model to investigate the effect of particle physical state and acidity on the uptake of S/IVOCs of different functional groups. In the controlled experiment, S/IVOCs were mixed with liquid, solid, partial neutralized to fully neutralized sulfate particles in a continuously mixed flow reactor. Solid sulfate particles represent one limit where uptake is limited to surface deposition (i.e., effectively infinitely small diffusion coefficient into the interior). Liquid sulfate particles took up significant amounts of S/IVOCs depending on the aerosol liquid water content, the extent of neutralization and the mixing time. An updated kinetic and thermodynamic model is being developed to estimate the gas-particle exchange of S/IVOCs to PM host composition under environmentally relevant conditions.