DEVELOPMENT AND APPLICATION OF A DUAL-IMPEDANCE RADIAL DIFFUSION-MODEL TO SIMULATE THE PARTITIONING OF SEMIVOLATILE ORGANIC-COMPOUNDS IN COMBUSTION AEROSOLS
Mr. Strommen et Rm. Kamens, DEVELOPMENT AND APPLICATION OF A DUAL-IMPEDANCE RADIAL DIFFUSION-MODEL TO SIMULATE THE PARTITIONING OF SEMIVOLATILE ORGANIC-COMPOUNDS IN COMBUSTION AEROSOLS, Environmental science & technology, 31(10), 1997, pp. 2983-2990
The fate of semivolatile organic compounds in the atmosphere is largel
y dependent on their partitioning between the gas phase and sorption t
o particulate matter. Since real atmospheres have been shown to deviat
e significantly from gas-particle equilibrium under certain conditions
, dynamic mass transfer models are needed to accurately predict partit
ioning. In this work, a dual-impedance radial diffusion model is prese
nted that is able to simulate the partitioning of deuterated fluoranth
ene in wood and diesel soot atmospheres generated in a large outdoor T
eflon film chamber. It is shown that the dual-impedance model produces
significantly better fits to experimental results than a one-layer mo
del and that surface mass transfer is not rate limiting in these syste
ms. The sensitivity of optimized apparent diffusion coefficients to ke
y input parameters is also explored. This work lays the foundation for
incorporating dynamic gas-particle partitioning models into larger at
mospheric models, such as urban airshed models. By conducting experime
nts under various conditions (e.g., temperature and humidity), values
for apparent diffusivities as a function of compound, particle source,
and atmospheric conditions may be developed. After including photoche
mical reactions, the model may be used to predict the fate of semivola
tile organic compounds in real atmospheres.