Manganese-Catalyzed Autoxidation of Dissolved Sulfur Dioxide in the Atmospheric Aqueous Phase

• Autoxidation of SO2(aq) in the presence of manganese(II) is one of the important pathways for sulfuric acid formation in atmospheric clouds and fogs. Recent experimental results indicating that the catalyzed reaction takes place via a complex free-radical mechanism are discussed. Previous literature is reviewed in the light of this mechanism. Under atmospheric conditions of low total concentrations of manganese(II) ( < 2 × 10−5 M) and sulfur(IV) ( ≤ 10−5 M) and 2.5 < pH < 5, the rate law for conversion of SO2(aq) to SO3(aq) is reduced to d[S(IV)]/dt = k[Mn(II)][S(IV)], where [S(IV)] denotes the total concentration. A value of the overall rate constant k of 1.4 × 103 M−1s−1 is recommended for use in atmospheric model calculations.

• Autoxidation of SO2(aq) in the presence of manganese(II) is one of the important pathways for sulfuric acid formation in atmospheric clouds and fogs. Recent experimental results indicating that the catalyzed reaction takes place via a complex free-radical mechanism are discussed. Previous literature is reviewed in the light of this mechanism. Under atmospheric conditions of low total concentrations of manganese(II) ( < 2 × 10−5 M) and sulfur(IV) ( ≤ 10−5 M) and 2.5 < pH < 5, the rate law for conversion of SO2(aq) to SO3(aq) is reduced to d[S(IV)]/dt = k[Mn(II)][S(IV)], where [S(IV)] denotes the total concentration. A value of the overall rate constant k of 1.4 × 103 M−1s−1 is recommended for use in atmospheric model calculations. Keywords Autoxidation; catalysis; manganese; sulfur dioxide; radicals; synergism; atmospheric droplets

Subject headings

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Keyword

Autoxidation

Catalysis

Manganese

Sulfur dioxide

Radicals

Synergism

Atmospheric droplets

Autoxidation

Catalysis

Manganese

Sulfur dioxide

Radicals

Synergism

Atmospheric droplets

Sulfuric acid formation

Acid rain

Publication and Content Type

art (subject category)

ref (subject category)