Quantifying the Reactive Uptake of OH by Organic Aerosols in aContinuous Flow Stirred Tank Reactor
Here we report a new method for measuring the heterogeneous chemistry of submicron organic aerosol particles using a continuous flow stirred tank reactor. This approach is designed to quantify the real time heterogeneous kinetics, using a relative rate method, under conditions of low oxidant concentration and long reaction times that more closely mimic the real atmosphere. A general analytical expression, which couples the aerosol chemistry with the flow dynamics in the chamber is developed and applied to the heterogeneous oxidation of squalane particles by hydroxyl radicals (OH) in the presence of O2. The particle phase reaction is monitored via photoionization aerosol mass spectrometry and yields a reactive uptake coefficient of 0.51+-0.10, using OH concentrations of 1-7x108 molec cdot cm-3 and reaction times of 1.5+-3 hours. This uptake coefficient is larger than that found for the reaction carried out under high OH concentrations (~;;1x1010 molec cdot cm-3) and short reaction times in a flow tube reactor. This difference suggests that oxidant concentration and reaction time are not interchangeable quantities in reactions of organic aerosols with radicals. In general, this approach provides a new way to examine how the chemical aging of organic particles measured at short reaction times and high oxidant concentrations in flow tubes might differ from the long reaction times and low oxidant levels found in the real atmosphere.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Chemical Sciences Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 973561
- Report Number(s):
- LBNL-2575E; TRN: US201006%%769
- Journal Information:
- Physical Chemistry Chemical Physics, Journal Name: Physical Chemistry Chemical Physics; ISSN 1463-9076
- Country of Publication:
- United States
- Language:
- English
Similar Records
Importance of sulfate radical anion formation and chemistry in heterogeneous OH oxidation of sodium methyl sulfate, the smallest organosulfate
Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield