Study of the SO₂ oxidation in solution and its role in atmospheric chemistry

Abstract

SUMMARYThe mechanism of SO, oxidation in diluted catalytic solutions was studied. It was found that the oxidation stops after a certain pH value is reached, In the same catalytic solutions, the maximum possible SO, -formation is a linear function of the SO, partial pressure in the air.This mechanism of SO, -formation can account for observed SO,-concentrations in rain, fog, and smog only if some neutralizing cations in the aerosols or traces of NH, in the air are present. It is shown that in the latter case the system SO,-NH,-catalytic solution can explain the main features of SOTformation in our atmosphere.

Aerosol Stabilization for Laboratory Studies of Aerosol-Gas Interactions

“…During the first 60 min of reaction, the average per cent conversion of SO 2 within the reactor was 21% for M11CI2, 31% for CuCl 2 , and less than 2% for NaCl. These results confirmed the chemistry finding by Junge and Ryan (1958), 3 and the biological proof by Amdur and Underhill (1968) 10 that sodium chloride is a poor catalyst for the SO2 to SO4 = conversion. Previous investigators have shown that the rates of catalytic oxidation of SO2 were highest at near saturated humidities; but no oxidation could be detected when the experimental relative humidity was lower than about 70%.…”

“…To avoid working with the aerosol-gas system in an airdispersed environment, other investigators attempted to transform or stabilize the aerosol prior to its exposure to gases. For example, Junge and Ryan (1958) 3 bubbled S0 2 and dry air mixtures through dilute catalyst solutions. But this approach to simulate an aerosol-gas system was unrealistic because the reaction kinetics could be drastically altered by the continuous mixing and by other mass transfer mechanisms.…”

Fate of ammonia in the atmosphere?a review for applicability to hazardous releases

“…In 1958, Junge and Ryan [81] observed that the rate of oxidation of S0 2 by oxygen was faster when the experiment was conducted using aerosol formed from sodium chloride solution spray in a polyethylene bag than when the reaction was conducted in bulk aqueous solutions. The same observation was made when ammonia was added to the bag containing a water aerosol and S0 2 .…”

Governing processes for reactive nitrogen compounds in the European atmosphere

“…H 2 SO 4 is formed from gas phase oxidation of SO 2 by hydroxyl (OH) radical or from aerosol phase conversion by hydrogen peroxide (H 2 O 2 ) and ozone (O 3 ). The latter process is pH dependent, and may be catalysed by NH 3 , since uptake of NH 3 increases the pH of aerosols (ApSimon et al, 1994;Junge and Ryan, 1958).…”