PHOTOCHEMICAL GENERATION OF NITROGEN DIOXIDE IN AQUEOUS SOLUTIONS

Solvated electrons, photochemically generated in aqueous K4Fe(CN)6 solutions, are allowed to react with NO3- ions. By applying flash techniques, it is shown that the reaction leads to the formation of dissolved NO2 molecules. The kinetics of the competition between the second-order disproportionation of NO2 and its scavenging by Fe(CN)6-4 are investigated, yielding k(NO2+Fe(CN)6-4) = (4.3 ± 1.0) × 106 M-1 sec-1, and an apparent k = (3.8 ± 1.4) × 107 M-1 sec-1 for the disproportionation of NO2. The mechanism of the decay of NO2 in water is discussed.