Modelling the natural photodegradation of water contaminants

Pajares, Adriana; Gianotti, José; Stettler, Guillermo; Bertolotti, Sonia G.; Criado, Susana; Posadaz, Ariana; Amat‐Guerri, F.; Garcı́a, Norman A.

doi:10.1016/s1010-6030(00)00416-0

Cited by 36 publications

(16 citation statements)

References 27 publications

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“…The shape of the spectrum obtained in the presence of 8 mM AHMPD (Fig. 3, main, lower trace) was similar to that already reported (17,30) to account for electron transfer processes to 3 Rf* from different electron-donor substrates of environmental and biological relevance (5,17,28,29,31), with the concomitant generation of the well-known anion radical Rf ·-(28, 29, 32, 33) (process [10]). The radical cation AHMPD ·+ that simultaneously appears was not detected, likely due to its absorption in a different wavelength range than the observed one, or to its very short lifetime.…”

Section: Quenching Of 3 Rf*supporting

confidence: 83%

“…3, main, upper trace) has been already reported for 3 Rf* (17,(26)(27)(28)(29). The shape of the spectrum obtained in the presence of 8 mM AHMPD (Fig.…”

Section: Quenching Of 3 Rf*supporting

confidence: 73%

“…Nevertheless, the role of Rf in the visible-light-promoted decomposition of hydroxy-N-heteroaromatic pesticides has been scantily investigated, and only with reference to pyridine derivatives (16,17), although this information is particularly important for the prediction of the photolysis rates of these contaminants in natural waters. For this reason, the main aim of the present work was to study the behavior of Rf as a sensitizer for the photodecomposition of the model fungicide AHMPD, as well as to gain information on the physical and chemical interactions taking place in this and similar systems.…”

Section: Introductionmentioning

confidence: 99%

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Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Haggi¹,

Bertolotti²,

Miskoski³

et al. 2002

Can. J. Chem.

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To clarify the evolution of pyrimidine fungicides under natural aquatic environmental conditions, the visiblelight-promoted degradation of the model fungicide 2-amino-4-hydroxy-6-methylpyrimidine (AHMPD) has been studied in air-equilibrated pH 6 aqueous solutions in the presence of riboflavin (Rf), employing time-resolved and stationary kinetic-spectroscopic methods. AHMPD, a compound practically inert towards the attack of singlet molecular oxygen (O 2 ( 1 D g )), quenches excited singlet and triplet states of Rf with rate constants of 2.7 × 10 9 M -1 s -1 and 2.7 × 10 7 M -1 s -1 , respectively. In the presence of AHMPD, the photodecomposition of Rf, which occurs from the excited triplet state of the pigment, depends on the concentration of the fungicide: at ³40-50 mM a limited photochemistry occurs due to the quenching of excited singlet Rf, while at ca. 5-10 mM triplet Rf is largely photogenerated and subsequently quenched either by oxygen, giving rise to O 2 ( 1 D g ), or by AHMPD, yielding semireduced Rf through an electron transfer process. Flash photolysis experiments and indirect auxiliary tests confirm the presence of superoxide anion generated by the reaction of Rf anion radical with the dissolved oxygen. The neat result of this intricate scheme of competitive reactions is the photodegradation of both AHMPD and Rf, mainly through a superoxide anion-mediated oxidation, although some contribution of O 2 ( 1 D g )-mediated photooxidations cannot be disregarded.Résumé : Dans le but de clarifier l'évolution des fongicides à base de pyrimidine dans les conditions environnementales aquatiques naturelles, on a étudié la dégradation du fongicide modèle 2-amino-4-hydroxy-6-méthylpyrimidine (AHMPD), sous l'influence de la lumière UV-vis, en solutions aqueuses à pH de 6 équilibrées avec l'air, en présence de riboflavine (Rf) et faisant appel à des méthodes spectroscopie résolues dans le temps et de cinétique stationnaire. L'AHMPD, un composé pratiquement inerte vis-à-vis des attaques par l'oxygène moléculaire singulet (O 2 ( 1 D g )), piège les états singulets et triplets excités de la Rf avec des constantes de vitesse de 2,7 × 10 9 M -1 s -1 et de 2,7 × 10 7 M -1 s -1 respectivement. En présence d'AHMPD, la photodécomposition de la Rf se produit à partir de l'état triplet excité et elle dépend de la concentration du fongicide: à des concentrations ³ 40-50 mM, la photochimie est limitée en raison du piégeage du singulet excité de la Rf alors que, aux environs de 5-10 mM, la Rf et pratiquement toute photogénérée avant d'être piégée ou par l'oxygène avec formation de O 2 ( 1 D g ) ou par l'AHMPD avec formation de Rf semiréduite par un processus de transfert d'électron. Des expériences de photolyse éclair et des tests auxiliaires indirects confirment la présence de l'anion superoxyde généré par la réaction du radical anion Rf avec l'oxygène dissous. Le résultat net de ce schéma complexe de réactions compétitives est une photogénération à la fois dAHMPD et de Rf, principalement par une oxydation par le superoxyde cata...

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Section: Quenching Of 3 Rf*supporting

confidence: 83%

“…3, main, upper trace) has been already reported for 3 Rf* (17,(26)(27)(28)(29). The shape of the spectrum obtained in the presence of 8 mM AHMPD (Fig.…”

Section: Quenching Of 3 Rf*supporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

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Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Haggi¹,

Bertolotti²,

Miskoski³

et al. 2002

Can. J. Chem.

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“…2. Moreover, the relatively lower value of the HAA S1 compared with the HAA T1 of RF (Table 1) may account, at least in part, for the higher reaction constants of the S 1 state than the T 1 state quenching processes ($10 9 vs $10 8 ) [5,6].…”

Section: H-atom Transfer Pathwaymentioning

confidence: 99%

“…1) and 4-hydroxypyridine (4-HP, Fig. 1) in the presence of RF, it was found that besides the ROS induced oxidation of the hydroxypyridines, 3-HP and 4-HP can quench both the singlet (S 1 ) and triplet (T 1 ) state RF directly [5,6]. However, the underlying quenching mechanisms need further investigations.…”

Section: Introductionmentioning

confidence: 95%

Mechanisms of singlet and triplet state riboflavin quenching by 3-hydroxypyridine and 4-hydroxypyridine. A quantum chemical study

Ji¹,

Shen²

2008

Journal of Molecular Structure: THEOCHEM

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Riboflavin Interactions with Oxygen—A Survey from the Photochemical Perspective

Insińska-Rak

Sikorski

2014

Chemistry A European J

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In this short review we provide some insights to the main processes that riboflavin is involved in upon absorption of a photon. We describe riboflavin properties in its interactions with oxygen, comparing them to the properties of some other singlet oxygen sensitizers. Data are provided on riboflavin photosensitizing properties in vivo and in vitro, and its properties as an endogenous singlet oxygen sensitizer are discussed. We additionally report flavin catalytic role in organic synthesis and photochemical reactivity in solutions of riboflavin and some of its derivatives.

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Modelling the natural photodegradation of water contaminants

Cited by 36 publications

References 27 publications

Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Mechanisms of singlet and triplet state riboflavin quenching by 3-hydroxypyridine and 4-hydroxypyridine. A quantum chemical study

Riboflavin Interactions with Oxygen—A Survey from the Photochemical Perspective

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Modelling the natural photodegradation of water contaminants

Cited by 36 publications

References 27 publications

Environmental photodegradation of pyrimidine fungicides  Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Environmental photodegradation of pyrimidine fungicides  Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Mechanisms of singlet and triplet state riboflavin quenching by 3-hydroxypyridine and 4-hydroxypyridine. A quantum chemical study

Riboflavin Interactions with Oxygen—A Survey from the Photochemical Perspective

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Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine

Environmental photodegradation of pyrimidine fungicides Kinetics of the visible-light-promoted interactions between riboflavin and 2-amino-4-hydroxy-6-methylpyrimidine