Phototransformations Induced in Aquatic Media by NO 3 - /NO 2 - , FeIII and Humic Substances

Boule, Pierre; Bolte, Michèle; Richard, Claire

doi:10.1007/978-3-540-69044-3_7

Cited by 35 publications

(52 citation statements)

References 118 publications

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“…DOM constituents, carbonate, bicarbonate, or nitrite) (Boule 1999). From the irradiation experiments it is possible to determine the initial formation rate of phenol from benzene, R P .…”

Section: Resultsmentioning

confidence: 99%

“…The collisional deactivation can be considerably faster than the reaction between 1 O 2 and most substrates, which would limit the importance of singlet oxygen in the photransformation processes (Boule 1999, and references therein). However, it has recently been shown that 1 O 2 could play a significant role toward the photochemical transformation of the amino acids histidine, methionine, tryptophan and tyrosine in surface waters (Boreen et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…• NO 2 , Cl 2 −• , Br 2 −• ) (Boule 1999). The cited reactions induce the transformation of dissolved compounds including manmade xenobiotics, limiting their persistence in the aquatic systems.…”

Section: Introductionmentioning

confidence: 99%

“…Among the reactive species mentioned before, 1 O 2 is generated in surface waters upon reaction between fundamental-state triplet oxygen and the triplet excited states of Dissolved Organic Matter ( 3 DOM*) (Boule 1999). 3 DOM* is produced upon radiation absorption by DOM, followed by Inter-System Crossing (ISC).…”

Section: Introductionmentioning

confidence: 99%

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Quantification of singlet oxygen and hydroxyl radicals upon UV irradiation of surface water

et al. 2009

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We measured the formation rate and the steady-state concentration of hydroxyl radicals and of singlet oxygen upon irradiation of lake water. There is controversy about the importance of singlet oxygen in the environmental photochemistry, but here we show that the steady-state concentration of 1 O 2 under irradiation can be higher by about two orders of magnitude compared to the hydroxyl radical. The higher occurrence of singlet oxygen in surface waters is mainly due to a higher rate of formation, because the transformation rate constants of 1 O 2 (collision with the solvent) and of • OH (reaction with dissolved compounds) are comparable.

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“…DOM constituents, carbonate, bicarbonate, or nitrite) (Boule 1999). From the irradiation experiments it is possible to determine the initial formation rate of phenol from benzene, R P .…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantification of singlet oxygen and hydroxyl radicals upon UV irradiation of surface water

et al. 2009

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“…Both of them can photogenerate the highly reactive, nonselective • OH thereby limiting the persistence of many pollutants that degrade relatively slowly by direct photolysis (19,20). Additionally, photolysis of HS leads to the formation of other reactive species, including 1 (25). Direct reactions between 3 HS* and organic substrates are likely to occur.…”

Section: Introductionmentioning

confidence: 99%

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Chen

et al. 2009

Environ. Sci. Technol.

208

114

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The photodegradation of the widely used amine drugs including primary amine (mexiletine), secondary amine (propranolol, phenytoin), and tertiary amine (diphenhydramine, antipyrine) were investigated in the presence of nitrate and humic substances under simulated sunlight. All of the amine drugs were photodegraded by nitrate due to the attack of hydroxyl radicals ( • OH). The bimolecular rate constants for the reaction between each amine drug and • OH ranged from (2.1 ( 0.2) × 10 9 to (8.7 ( 0.3) × 10 9 M -1 s -1 . In contrast, only mexiletine, propranolol, and diphenhydramine were selectively photodegraded in the presence of humic substances (HS). Fulvic acid was a more efficient sensitizer than humic acid throughout. The HS triplet states were verified to be main reactive species in the photochemical reaction. Furthermore, an electron transfer mechanism for the reaction with the HS triplet states was proposed on the basis of all information obtained under a series of experiments. The electron transfer from the nonbonding electrons on nitrogen (N-electrons) of the amine drugs to the excited ketone of the HS occurred. The availability of N-electrons and presence of hydrogen on carbon R of amine (R-hydrogen) were two key factors for the electrontransfer interaction. Moreover, the photoproducts were identified by GC-MS and the degradation pathways were proposed. The results strongly suggest the impact of humic substances on the photochemical fate of amine drugs in the natural waters.

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Direct and induced phototransformation of mecoprop [2-(4-chloro-2-methylphenoxy)propionic acid] in aqueous solution

Meunier

Boule

2000

Pest Manag. Sci.

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Mecoprop was irradiated under various conditions of pH, oxygenation and wavelengths in order to study the reactions involved in the phototransformation. Four main photoproducts were identi®ed: 2-(4-hydroxy-2-methylphenoxy)propionic acid (I), o-cresol (II), 2-(5-chloro-2-hydroxy-3-methylphenyl)propionic acid (III) and 4-chloro-o-cresol (IV). When the anionic form of mecoprop was irradiated between 254 nm and 310 nm (UV-C or UV-B), I was the main photoproduct. At 254 nm its formation initially accounted for more than 80% of the transformation. It has not previously been reported in the literature. The reaction results from a heterolytic photohydrolysis. Product II accounted for only a low percentage of the transformation. The stoichiometry was different with the molecular form: the main photoproduct, III, resulted from a rearrangement after a homolytic scission. Products I, II and IV were also formed as minor photoproducts. Some other minor photoproducts were also identi®ed. In contrast, IV was the main photoproduct under sunlight irradiation or when solutions were irradiated in near-UV light (UV-A). This wavelength effect is attributed to the involvement of an induced phototransformation; IV is also the main photoproduct when the phototransformation is induced by Fe(III) perchlorate or nitrite ions. In usual environmental conditions the excitation of the molecular form is negligible and the phototransformation is mainly due to induced photoreactions.

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Phototransformations Induced in Aquatic Media by NO 3 - /NO 2 - , FeIII and Humic Substances

Cited by 35 publications

References 118 publications

Quantification of singlet oxygen and hydroxyl radicals upon UV irradiation of surface water

Quantification of singlet oxygen and hydroxyl radicals upon UV irradiation of surface water

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Direct and induced phototransformation of mecoprop [2-(4-chloro-2-methylphenoxy)propionic acid] in aqueous solution

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