Photodégradation de l'atrazine en milieu aqueux par irradiation UV en absence et en présence de peroxyde d'hydrogène

Tace, Elmostafa; Laat, J. De; Doré, M.

doi:10.1051/water/19922302233

Cited by 7 publications

(6 citation statements)

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“…Since PAHs are nondissociating com- pounds in water with constant extinction coefficient and quantum yield, variation of oxidation rate should also be due to competition between reactions (1)-( 5). In fact, the increase of pH also yields two opposing effects: on the one hand, there is an improvement of hydroxyl radical formation through reaction (1) since at 254 nm the extinction coefficient of the ionic form of hydrogen peroxide, the hydroperoxide ion (major peroxide species at pH 12), 240 M -1 cm -1 (Tace, 1992), is higher than that of the nonionic form, 19 M -1 cm -1 . On the other hand, the consumption rate of hydroxyl radicals by hydrogen peroxide due to reactions (3) and ( 4) also increases because the hydroperoxide ion reacts faster than the nonionic form.…”

Section: Resultsmentioning

confidence: 99%

“…In their work, a priority pollutant 1,2-dibromo-3-chloropropane is treated with UV/H 2 O 2 , O 3 /H 2 O 2 , and UV/O 3 systems, and a kinetic model is proposed for the former process based on chemical and photochemical principles. Different chloroethanes and s-triazine herbicides have also been treated with the UV/H 2 O 2 system by Tace (1992). In a recent work, Beltra ´n et al (1993) also report on results of the chemical and photochemical degradation of atrazine with UV/H 2 O 2 oxidation.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 3. UV Radiation Combined with Hydrogen Peroxide

Beltrán

Ovejero

Rivas

1996

Ind. Eng. Chem. Res.

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Oxidation in water of three polynuclear aromatic hydrocarbons (PAHs), fluorene, phenanthrene, and acenaphthene, with UV radiation combined with hydrogen peroxide has been studied. The effect of hydrogen peroxide concentration, pH, and bicarbonate ion has been investigated. Disappearance rates of PAHs are substantially increased with respect to those from UV radiation alone if proper conditions of hydrogen peroxide concentration and pH are established. Direct photolysis contribution decreases with the increasing hydrogen peroxide concentration and is the main way of degradation at acid pH (76% at pH 2 with 10 -3 M hydrogen peroxide concentration, for fluorene oxidation). Rate constants of reactions between the hydroxyl radical and PAHs were found to be 9.9 × 10 9 , 8.8 × 10 9 , and 13.4 × 10 9 M -1 s -1 , for fluorene, acenaphthene, and phenanthrene, respectively. Both UV radiation and UV/H 2 O 2 oxidation of PAHs yield numerous intermediate compounds. Most of these compounds disappear as oxidation time is increased.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 3. UV Radiation Combined with Hydrogen Peroxide

Beltrán

Ovejero

Rivas

1996

Ind. Eng. Chem. Res.

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“…The PAHs in the H 2 O 2 /UV system disappear due to direct photolysis and to their reaction with hydroxyl radicals. In alkaline solution part of the light absorbed by hydrogen peroxide, exactly its ionic formhydroperoxide anion (3), increases since the extinction coefficient increases from 19 M −1 cm −1 for H 2 O 2 [21] 240 M −1 cm −1 for HO − 2 [11]. This diminishes the formation of hydroxyl radicals according to equation (1).…”

Section: Influence Of Parametersmentioning

confidence: 99%

“…This technique was widely used for destruction of various harmful compounds e.g. phenol [9], pentachlorophenol [10], halogenoalkanes [11], pesticides [12], surfactants [13]. PAHs were also the object of studies in the H 2 O 2 /UV system.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

Ledakowicz

Miller

Olejnik

1999

International Journal of Photoenergy

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The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene, chrysene and fluorene in aqueous solution using advanced oxidation processH2O2/UVwas investigated. The influence of pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentration (ca. 0.01 M). The degradation of benzo[a]pyrene and chrysene follows radical reaction, for fluorene the mechanism is not clear. The rate constants of the hydroxyl radicals and selected PAHs reaction were found to be2.53×1010,9.82×109and2.77×109M−1S−1for benzo[a]pyrene, chrysene and fluorene, respectively

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“…Ces valeurs ont été calculées par les différents auteurs avec des valeurs de coefficient d'extinction molaire variant de 2500 à 4000 I moh 1 cm -1 à 254 nm (NICK et ai, 1992 ;TACE et al, 1992;BELTRAN étal., 1993 ;HESSLER ef al. , 1993 ;DE LAAT étal., 1995).…”

Section: Oxydation Par Hfl^uvunclassified

Oxydation de S-triazines par les procédés d'oxydation radicalaire. Sous-produits de réaction et constantes cinétiques de réaction

Laat¹,

Doré²,

Suty³

2005

rseau

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L'étude bibliographique montre que l'oxydation de l'atrazine en milieu aqueux par 03, 03/H202, 03/UV, H202/UV et TiO2/UV ne permet qu'une dégradation limitée du pesticide (pas d'ouverture de l'hétérocycle azoté). Ces procédés d'oxydation conduisent aux mêmes sous-produits d'oxydation. Les composés N-déalkylés, les acétamido-s-triazines et l'hydroxyatrazine constituent les premiers sous-produits de dégradation de l'atrazine. Une oxydation plus poussée conduit par des réactions de N-déalkylation, d'hydroxylation et de déamination à la formation de produits finals relativement stables comme la déséthyldésisopropylatrazine, l'amméline, l'ammélide et l'acide cyanurique. La distribution des différents sous-produits en cours d'oxydation dépend du procédé d'oxydation utilisé, des conditions de mise en oeuvre du procédé (dose d'oxydants ou d'UV, longueur d'onde d'irradiation,...), des caractéristiques des eaux de dilution (pH, pièges à radicaux hydroxyles,...).Les études cinétiques indiquent que l'atrazine est relativement réfractaire à une oxydation par l'ozone moléculaire (constante cinétique de l'ordre de 6 l mol-¹ s-¹ à 20 °C) et est assez réactive vis-à-vis des radicaux hydroxyles (constante cinétique de l'ordre de 2,5 10·9 mol-¹ s-¹ à 20 °C). En ce qui concerne les constantes cinétiques de réaction des radicaux hydroxyles sur les autres s-triazines, les résultats montrent que les méthylthio s-triazines sont beaucoup plus réactives que les méthoxy s-triazines qui sont elles mêmes légèrement plus réactives que les chloro et hydroxy s-triazines. Parmi les sous-produits d'oxydation de l'atrazine, la déséthyldésisopropylatrazine et l'acide cyanurique sont très réfractaires à une oxydation par les radicaux hydroxyles et par l'ozone moléculaire.In this paper, oxidation studies of s-triazines in aqueous solution by advanced oxidation processes (O3, O3/H2O2, O3/UV, H2O2/UV, et TiO2/UV) have been reviewed.Oxidation by-products of atrazine:Several investigators have shown that N-dealkylated (deethylatrazine and deisopropylatrazine) and acetamido-s-triazines are the primary oxidation by-products of atrazine by O3 and by O3/H2O2 (table 1; fig. 1a). Under conditions which favored the production of hydroxyl radicals (03/H2O2), trace amounts of hydroxyatrazine may also be formed. These primary by-products are subsequently degraded to give complete N-dealkylated, deamined, dehalogenated and hydroxylated s-triazines (deethyldeisopropylatrazine, ammelide ammeline, cyanuric acid,...) (table 1). For example, oxidation of deethylatrazine by O3/H2O2 yields deethyldeisopropylatrazine as the major by-product (fig. 1b). Identical by-products are produced by photochemical oxidation (O3/UV, H2O2/UV and TiO2/UV) (table 2; fig. 4 and 5). UV photolysis of atrazine at 253.7 nm (monochromatic radiation) yields hydroxyatrazine as the major product (=0.95 -1.0 mole of hydroxyatrazine formed / mole of atrazine photolysed (fig. 4a) whereas N and N,N'-dealkylated, deaminated and hydroxyderivatives are produced by UV irradiation in the presence of ozone,...

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Photodégradation de l'atrazine en milieu aqueux par irradiation UV en absence et en présence de peroxyde d'hydrogène

Cited by 7 publications

References 0 publications

Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 3. UV Radiation Combined with Hydrogen Peroxide

Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 3. UV Radiation Combined with Hydrogen Peroxide

Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

Oxydation de S-triazines par les procédés d'oxydation radicalaire. Sous-produits de réaction et constantes cinétiques de réaction

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