Laser-Spectroscopic Measurements of Uptake Coefficients of SO₂ on Aqueous Surfaces

Abstract

The uptake of SO 2 on aqueous surfaces was studied by directly measuring SO 2 concentration distribution above the surface by means of laser-induced fluorescence method in an impinging flow field with a 10-100 ms order contact time between the gas flow containing SO 2 and the water flow. The uptake coefficient was determined by using the eq which describes the boundary condition at the surface. The uptake coefficient increased with pH of the aqueous phase and reached the limiting value of 0.028 ( 0.010 at pH ) 13.2 at 293.5 K. Its temperature dependence was slightly negative. The present uptake coefficients could be understood satisfactorily by taking into account the rapid acid-dissociation reaction of dissolved SO 2 with the reported bulk reaction rate constant.

Mass Accommodation and Chemical Reactions at Gas−Liquid Interfaces

“…While comparable temperature dependent studies as presented above are relatively sparse, additional single temperature measurements can be compared to the corresponding points from temperature dependent studies. For example, room temperature droplet train flow reactor results for SO 2 and HNO 3 uptake obtained by Ponche et al 42 are in fair to good agreement with the BC/ARI temperature dependent studies, 32,82 as are room temperature coaxial liquid jet measurements for SO 2 , HC(O)OH, and CH 3 C(O)OH by Schurath et al 91 Shimono and Koda used a novel impinging flow method to measure a 293 K value of R ) 0.2 for SO 2 , 92 in reasonable agreement with the droplet train flow reactor results. Similarly, a droplet train flow reactor measurement for phenol at 283 K yielding R ) 0.027 ( 0.005 93 is in excellent agreement with the temperature dependent wetted wall flow reactor data of Mu ¨ller and Heal 94 that yielded values of 0.037 at 278 K and 0.012 at 288 K. Heal et al 93 also measured R ) 0.018 ( 0.005 for aniline at 283 K and reported an upper limit of 0.001 for toluene.…”

SO2:H2O Surface Complex Found at the Vapor/Water Interface

“…5 However, more recent measurements suggest the uptake coefficients can be determined from the bulk reaction rate constant. 10 Surface second harmonic generation studies of sodium bisulfite solutions suggested evidence for a surface complex. 8 Subsequent MD simulations 9 suggest that a 1:1 SO 2 :H 2 O surface complex is not stable enough to be this species.…”

Theoretical investigation of a potentially important formation pathway of organosulfate in atmospheric aqueous aerosols

“…Here we develop a chemical kinetic model using the results from our quantum chemical modeling to simulate the effects of HMS/HMSA and HMSi/HMHSi formation on the aerosols (refer to SI for the reaction scheme). In the simulations, we made the following assumptions based on the concentrations during a typical haze event: the droplet diameter = 2.5 μm, temperature = 298.15 K, the pressure = 1.0 atm, [SO 2 ] = 50 ppb, the total amount of formaldehyde and methanediol in the droplet = 5.0 × 10 −5 μM 17,18 , the uptake coefficient 19 of SO 2 adsorption = 5.0 × 10 −3 , initial pH = 5.0. The initial concentrations of all the products (i.e.…”