AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Secondary Organic Aerosol Production from Pinanediol, a Semi-Volatile Precursor
PENGLIN YE, Yunliang Zhao, Wayne Chuang, Neil Donahue, Carnegie Mellon University
Abstract Number: 525 Working Group: Aerosol Chemistry
Abstract We have investigated the production of secondary organic aerosol (SOA) from pinanediol (PD), a precursor chosen as a semi-volatile surrogate for the first-generation oxidation products of monoterpenes. Because PD is semi volatile, we assessed its interactions with the CMU Teflon smog-chamber walls before determining SOA mass yields from PD oxidation. PD showed a large chamber wall deposition and reached a steady-state concentration with only 14% left in the gas phase. We observed a factor of three increase in the PD vapor concentration when increasing the chamber temperature from 13 to 44 oC, consistent with the release of PD from the chamber walls. However, we did not observe significant release of PD during isothermal dilution of the chamber with fresh air at 22 oC, which simulated the depletion of PD during isothermal oxidation and SOA production. Consequently, we consider the release of PD from the chamber walls to be negligible under our experimental conditions. As with the PD itself, we also consider wall losses of the PD oxidation products forming SOA. As a first-order approximation, we assume that the condensation of PD oxidation products to the Teflon is effectively irreversible. The condensation of oxidation products to the suspended particles competes with the direct vapor chamber wall loss. The fraction is determined by the condensation sink of the suspended particles and the vapor wall loss rate, which we assume to be a constant, 1/16 min-1, based on our earlier measurements of semi-volatile organic wall losses. After correcting for both particle and vapor wall losses we obtain the SOA mass yields from PD of between 0.1 and ~1, which are 2-3 times larger than monoterpenes.