Laboratory determination of the mass accommodation coefficients for sulfur-dioxide and hydrogen peroxide on aqueous droplets at 292 Kelvin

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6877699

Gardner, II, J A

Heterogeneous reaction pathways involving water droplets are important mechanisms for chemical transformations of atmospheric trace gases. One of the fundamental parameters which determines the transfer rate of gases into aqueous droplets is the mass accommodation coefficient for gas molecules on the droplet surfaces. The mass accommodation coefficient ({gamma}) is defined simply as the probability that a molecule which strikes the liquid surface enters into the bulk liquid. The author has developed a laboratory method for directly determining mass accommodation coefficients and have applied this method to SO{sub 2} and H{sub 2}O{sub 2}. The method combines a monodisperse droplet stream, generated by a vibrating orifice, with a low-pressure flow reactor. The uptake of the trace gas by the droplets is determined by measuring changes in gas phase concentrations, using tunable diode laser infrared absorption, as the droplet stream is turned on and off. Experiments with systematic variation of pressure and gas composition permit deconvolution of the effects of gas phase diffusion on the uptake of the trace gases. In the case of SO{sub 2}, variation of droplet composition and variation of droplet-gas interactions on millisecond time scales resolved pH dependent saturation effects at the aqueous surface. Results for SO{sub 2} show {gamma} = 0.11 {+-} 0.01 at 292 K. Results for H{sub 2}O{sub 2} show {gamma} = 0.13 {+-} 0.03 at 292 K. The results are interpreted and discussed, in terms of both information regarding surface chemical reactions and the implications of the results for atmospheric chemistry problems.

• Research Organization: Boston Coll., Chestnut Hill, MA (USA)
• OSTI ID: 6877699
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ABSORPTION
ATMOSPHERIC CHEMISTRY
BENCH-SCALE EXPERIMENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DIFFUSION
DROPLETS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
MASS TRANSFER
MEASURING METHODS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PEROXIDES
PH VALUE
SORPTIVE PROPERTIES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
SURFACE PROPERTIES
TIME DEPENDENCE
WATER