Uptake of gas-phase formaldehyde by aqueous acid surfaces
- Aerodyne Research, Inc., Billerica, MA (United States)
- Boston College, Chestnut Hill, MA (United States)
The uptake of gas-phase formaldehyde, CH{sub 2}O, by aqueous sulfuric and nitric acid droplets has been measured as a function of temperature, acid concentration, and gas-droplet contact time. The results are interpreted in terms of the mass accommodation coefficient for formaldehyde on aqueous surfaces, the Henry`s law constant for formaldehyde in aqueous acid solutions, and the liquid-phase formation kinetics of methylenediol, CH{sub 2}(OH){sub 2}, and protonated formaldehyde, CH{sub 3}O{sup +}. Time-dependent uptake studies under mildly acid solutions where CH{sub 2}(OH){sub 2} and CH{sub 3}O{sup +} formation is slow reveal the existence of a chemisorbed surface complex for CH{sub 2}O at the gas-liquid interface. Uptake studies on nitric acid and mixed sulfuric acid/nitric acid solutions show slightly enhanced uptake relative to sulfuric acid only solutions. This observation has been attributed to variation of formaldehyde solubility (expressed as Setchenow coefficients) and CH{sub 3}O{sup +} equilibrium constant in nitric and sulfuric acid solutions. The implications of these measurements for the aqueous acid chemistry of formaldehyde and its role in atmospheric chemistry are discussed. 46 refs., 7 figs., 2 tabs.
- DOE Contract Number:
- FG02-94ER61854
- OSTI ID:
- 263223
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 19 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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