Effects of ions and electrons on atmospheric lifetimes of fully fluorinated compounds

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:182830

Morris, R A; Miller, T M; Viggiano, A A; Paulson, J F ^[1]; Solomon, S; Reid, G ^[2]

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1. Phillips Lab., Hanscom AFB, MA (United States)
2. NOAA Aeronomy Lab., Boulder, CO (United States)

Fully fluorinated compounds (perfluoro compounds) represent a class of chemicals which include many extremely inert species-inert to both chemical reaction and photodissociation. Well known examples include SF6 and the perfluorocarbons (PFCs) CF{sub 4} and Teflon. SF{sub 6} is used industrially in electrical switch gear and as an atmospheric tracer. CF{sub 4} and C{sub 2}F{sub 6} are released into the atmosphere as a by-product of aluminum manufacture. Several perfluoro compounds have been proposed as substitutes for the ozone-destroying Freons and halons; proposed substitutes include SF{sub 6}, c-C{sub 4}F{sub 8}, C{sub 5}F{sub 12}, and C{sub 6}F{sub 14}. These chemicals were chosen in part because they do not harm the stratospheric ozone layer and were therefore considered environmentally friendly. Recently, Ravishankara et al. reported that perfluoro compounds have significant global warming potential (GWP), contributing to the greenhouse effect due to strong infrared absorption. The perfluoro compounds have particularly high GWPs because their atmospheric lifetimes are exceedingly long, on the order of millennia. The long lifetimes are the result of the extreme inertness toward the processes which remove most trace chemicals from the atmosphere, i.e., photodissociation and reaction with radicals. The lifetime predictions were based on a model which did not include removal by ion and electron reactions. For this reason the authors have studied five perfluoro compounds for reactivity toward electrons and the atmospheric ions O{sup +}, O{sub 2}{sup +}, O{sup {minus}}, O{sub 2}{sup {minus}}, NO{sup +}, H{sub 3}O{sup +}, NO{sub 3}{sup {minus}}, and CO{sub 3}{sup {minus}}. The selected perfluoro chemicals were SF{sub 6}, CF{sub 4}, C{sub 2}F{sub 6}, c-C{sub 4}F{sub 8}, and C{sub 6}F{sub 14}. Several samples of C{sub 6}F{sub 14} with different purities and isomeric composition were used.

• OSTI ID: 182830
• Report Number(s): CONF-940426--; ISBN 0-923204-11-3
• Country of Publication: United States
• Language: English

Related Subjects

29 ENERGY PLANNING, POLICY, AND ECONOMY
54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC CHEMISTRY
ENVIRONMENTAL EFFECTS
EXPERIMENTAL DATA
FREONS
GREENHOUSE EFFECT
HALOGENATED ALIPHATIC HYDROCARBONS
MATERIAL SUBSTITUTION
OZONE LAYER
PHOTOCHEMICAL REACTIONS