Miniflow reactor for long-time aging of aerosols without wall effects

ENVR 112

James P. Cowin, jp.cowin@pnl.gov1, Xin Yang, yangxin@fudan.edu.cn2, and Martin J. Iedema, martin.iedema@pnl.gov1. (1) Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Box 999, M/S K8-88, Richland, WA 99352, (2) Department of Environmental Science & Engineering, Fudan University, Shanghai, 200433, China
Kinetics measurements of long time (> day) aging of aerosols with trace gases require huge aerosol chambers (e.g., >10m) to minimize "wall effects". More convenient, supported-aerosol methods can require extremely unreactive substrates (γs<<10-5 averaged over the substrate) and less than picogram/cm2 particle loadings, to eliminate gross transport-limited trace gas depletion. These limitations are avoided in a new mini-flow-reactor (.003 m), with 102-105 supported particles and subsequent sensitive (single) particle analysis. The flow (550 cm/s) creates a 2μm "zone of isolation" around each particle where γs < 0.1 locally (within 2μm) is acceptable. Measured with it was the reactive uptake of gaseous HNO3 with deliquescent NaCl particles. The initial reactive uptake coefficient γreac at 80% RH for 0.8-2μm (wet) diameter particles was found to be 4.9±0.3×10-3, independent of particle size.
 

General Papers
6:00 PM-8:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Environmental Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007