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Direkte Photolyse und Reaktion von Nitrophenolen und Nitrobenzoesäuren mit OH-Radikalen in umweltrelevanten, wässrigen Systemen

Direct photolysis reaction of nitrophenols and nitrobenzoic acids with OH radicals in environmentally relevant aqueous systems
 
: Palm, W.-U.; Zetsch, C.

Jekel, M. ; Gesellschaft Deutscher Chemiker -GdCh-, Fachgruppe für Wasserchemie:
Vom Wasser. Ein Jahrbuch für Wasserchemie und Wasserreinigungstechnik. Bd.95
Weinheim: Wiley-VCH, 2000 (Vom Wasser 95)
ISBN: 3-527-30167-4
pp.47-56
German
Book Article
Fraunhofer ITA ( ITEM) ()
nitrobenzoic acid; direct photolysis; quantum yield; OH rate constant; nitrophenol; OH radical; atmosphere; cloud

Abstract
Nitrophenols (4-methyl-2-nitrophenol, 2,4-dinitrophenol, 2,6-dinitro-p-cresol) and nitrobenzoic acids (3-nitrobenzoic acid, 4-methyl-3-nitrobenzoic acid) were investigated with respect to direct photolysis and OH-radical reactivity in aqueous solution. Quantum yiels and OH-rate constants determined were used to calculate half-lives in surface water and cloud water and by using an incremental system in the gas phase for comparison. Direct photolysis calculated from the quantum yields (6 . 10-4 < phi < 4 . 10-7) with half-lives in the range of weeks is a slow process compared to OH-reactivity. Using nitrobenzene and benzoic acid as reference compounds OH-rate constants (6.6 . 10/9 < k OH/M -1 s-1 < 10.5 . 10/9) were found to be high and at the diffusion limit, as known for most aromatics in aqueous solution. Low half-lives in the range of hours are calculated in cloud waters due to their high OH levels. The influence of pH in the distribution between the aqueous phase and gas phase and their contribution to degradation is discussed.

: http://publica.fraunhofer.de/documents/N-9864.html