title: Heterogeneous uptake of 8-2 fluorotelomer alcohol on liquid water and 1-octanol droplets.
abstract: The heterogeneous uptake of the 8-2 fluorotelomer alcohol, F(CF2)8CH2CH2OH, on liquid water surfaces over the temperature range 256-273 K and on 1-octanol surfaces over the temperature range 264-295 K has been investigated with a droplet train flow reactor. The uptake coefficient on water droplets is zero within the error of the measurement (+/-0.01) and is independent of droplet temperature. In contrast, significant uptake onto 1-octanol is observed. Measured uptake coefficients for 1-octanol showed a negative temperature dependence, varying from 0.034 +/- 0.005 (1sigma) at 295 K to 0.103 +/- 0.009 at 264 K. The measured uptake coefficients on 1-octanol were independent of gas-liquid contact time, for typical contact times varying between 3 and 15 ms, and independent of the 8-2 fluorotelomer alcohol gas-phase concentration, indicating that the uptake coefficients are equivalent to mass accommodation coefficients. The uptake coefficients on 1-octanol were also independent of relative humidity. These results show that the uptake of FTOHs on or into the aqueous component of cloud/fog droplets or aqueous aerosol particles is not likely to be an important atmospheric sink for these compounds. In these experiments, 1-octanol was used as a model compound for organic-containing atmospheric particles. The larger uptake coefficient measured for 1-octanol surfaces indicates that FTOH partitioning to organic-containing cloud/fog droplets and aerosol particles may be an atmospheric loss mechanism.
authors.affiliation: Atmospheric Sciences Research Center, State University of New York, 251 Fuller Road, Albany, New York 12203, USA.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Li
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Demerjian
authors.forename: Leah R
authors.initials: LR
authors.lastname: Williams
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Worsnop
authors.forename: Charles E
authors.initials: CE
authors.lastname: Kolb
authors.forename: Paul
authors.initials: P
authors.lastname: Davidovits