Ozone as a sink for atmospheric carbon aerosols

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7273160

Stephens, S L

Critical information necessary for examining the chemical removal of smoke in the atmosphere by the reaction with ozone has been obtained. The kinetics, products and temperature dependence of the reaction of ozone with carbonaceous material was determined. This information can be included in models examining the fate of ozone and smoke in the atmosphere. The rate of ozone loss was followed in its reaction with carbon black at room temperature. In addition to the ozone loss, the gaseous products, CO, CO[sub 2] and O[sub 2] were quantified with a phase locking mass spectrometer attached to a two-chamber Knudsen cell reactor. An oxygen molecule was detected for every ozone lost. The initial loss rate was much greater than that seen after extended exposure to ozone. Oxygen atoms were desorbed 30% of the time as CO or CO[sub 2] and those left behind on the surface were responsible for the decrease in rate. Heating the surface following this exposure would liberate CO and CO[sub 2] and restore the initial reactivity. The reaction of ozone with different types of soot was examined by following the decrease of optical depth of soot deposited on a quartz slide at temperatures from 21[degrees] to 174[degrees]C. The reaction kinetics were very similar for the four types of soot used in this study. Treating all types together the activation energy and the order with respect to ozone were 10.9 ([+-]1.0) kcal mol[sup [minus]1] and 0.89 ([+-]0.14), respectively. The lifetime of soot under atmospheric conditions was calculated to be on the order of years to decades. The reaction of ozone with acetylene smoke suspended in air was the final method of examining the reaction. The change of acetylene smoke size distribution and ozone concentration was monitored while controlling the temperature. Irreproducibility caused this study to be unsuccessful. This was believed to be due to contamination leaking into the teflon bags in which the experiments were conducted.

• Research Organization: Colorado Univ., Boulder, CO (United States)
• OSTI ID: 7273160
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AEROSOLS
AIR POLLUTION CONTROL
ATMOSPHERIC CHEMISTRY
CARBON SINKS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COLLOIDS
CONTROL
DISPERSIONS
KINETICS
OZONE
POLLUTION CONTROL
REACTION KINETICS
RESIDUES
SINKS
SMOKES
SOLS
SOOT