es9b02974_si_001.pdf (1.24 MB)
Atmospheric Fate and Impact of Perfluorinated Butanone and Pentanone
journal contribution
posted on 2019-07-23, 03:13 authored by Yangang Ren, François Bernard, Véronique Daële, Abdelwahid MelloukiPerfluoroketones,
used as replacement to halons and CFCs, are excluded
from the Montreal Protocol because they are considered as nonozone
depleting substances. However, their chemical structure makes them
possible greenhouse gases if their atmospheric lifetimes are long
enough. To assess that possibility, we investigated the photolysis
of perfluoro-2-methyl-3-pentanone (PF-2M3P), and perfluoro-3-methyl-2-butanone
(PF-3M2B) using outdoor atmospheric simulation chambers. In addition,
the photolysis of a non fluorinated pentanone (2-methyl-3-pentanone,
2M3P) was studied. The results showed that photolysis is the dominant
loss pathway of PF-2M3P and PF-3M2B in the troposphere whereas 2M3P
is lost by both photolysis and gas phase reaction with atmospheric
oxidants. The photolysis effective quantum yields of PF-2M3P, PF-3M2B,
and 2M3P were estimated and some of the main products identified.
The photolysis of PF-2M3P and PF-3M2B was found to have a minor impact
on the atmospheric burden of fluorinated acids. The atmospheric lifetimes
of PF-2M3P, PF-3M2B, and 2M3P were estimated to 3–11 days,
∼13 days, and 1–2 days, respectively. Combining the
obtained data, it has been concluded that with 100-year time horizon
global warming potentials (GWP100) equivalent to <0.21,
∼0.29, and ≤1.3 × 10–7 for PF-2M3P,
PF-3M2B, and 2M3P, respectively, these compounds will have a negligible
impact on global warming.