Yg. Zuo et J. Hoigne, PHOTOCHEMICAL DECOMPOSITION OF OXALIC, GLYOXALIC AND PYRUVIC-ACID CATALYZED BY IRON IN ATMOSPHERIC WATERS, Atmospheric environment, 28(7), 1994, pp. 1231-1239
Kinetics of the iron(III) catalysed photochemical degradation of oxali
c, glyoxalic and pyruvic acids has been investigated under conditions
representative of atmospheric waters. Degradation rates for the organi
c acids are proportional to the concentration of iron (III)-substrate
complexes and sunlight intensity. Under September noon sunlight irradi
ation (0.65 m Einstein m-2 s-1), 1 muM dissolved iron(III) has a poten
tial to catalyse the degradation of oxalic acid at a rate of 10 +/- 1
nM s-1; of glyoxalic acid, 7 +/- 1 nM s-1; and of pyruvic acid, 8 +/-
1 nM s-1. The half life for the photolysis of oxalic acid and alpha-ke
to acids catalysed by iron(III) is in the order of a few minutes whene
ver the concentration of dissolved iron(III) is comparable to that of
the organic acids. A detailed reaction mechanism has been proposed in
which the complex formation between iron(III) and the substrate is a k
ey step. The evidence, that such an iron(III) catalysed photochemical
process serves as a major removal pathway for atmospheric oxalic and a
lpha-keto acids, has also been discussed.