Kinetics and Mechanism of Photodegradation of Chlorophenols

Burrows, Hugh D.; Ernestova, L. S.; Kemp, Terence J.; Skurlatov, Yuri I.; Purmal, A. P.; Yermakov, A. N.

doi:10.3184/007967498103165022

Cited by 62 publications

(60 citation statements)

References 233 publications

(432 reference statements)

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“…Acetonitrile was found to have no quenching effect in the present study; this was in agreement with previous studies where acetonitrile was reported to be the most suitable cosolvent for photolysis studies [23]. However, it was found that emamectin tended to bind irreversibly to the glass of the photolysis vessel after drying, making it infeasible to study the photodegradation of this compound without the use of a cosolvent.…”

Section: Resultssupporting

confidence: 80%

The role of indirect photolysis in limiting the persistence of crop protection products in surface waters

Wallace

Hand

Oliver

2009

Enviro Toxic and Chemistry

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The photodegradation of six crop protection products (CPPs) was studied in 16 natural waters collected from across the midwest of the United States under simulated sunlight to determine the significance of indirect photolysis. The rate of degradation of five of the CPPs was faster in irradiated natural waters than in buffer systems, with the effect particularly significant with the relatively photostable compounds propiconazole and prometryn. Degradation rates were correlated with the concentration of one or more photosensitizers, or ratios thereof, by means of a Pearson's correlation and linear regression analysis. It was found that the photodegradation of chlorotoluron, pinoxaden, propiconazole and prometryn were linked to the concentration of nitrate, pointing to a significant role of hydroxyl radical ((.)OH) as a reactive intermediate. Increased concentrations of dissolved organic carbon (DOC) and bicarbonate relative to nitrate were found to decrease the rate of degradation of these compounds, consistent with a quenching role. Chlorothalonil appeared to be rapidly degraded by means of the carbonate radical ((.)CO(3)(-)), whereas the photodegradation of emamectin was particularly complex. Overall, indirect photolysis significantly enhanced the rate of CPP degradation and fate models based on these experiments appear to offer more realism than those that only take into account direct photolysis.

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Section: Resultssupporting

confidence: 80%

The role of indirect photolysis in limiting the persistence of crop protection products in surface waters

Wallace

Hand

Oliver

2009

Enviro Toxic and Chemistry

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“…4-Chlorophenol was the subject of many publications [1,8,11,12,13,14,15,16,17]. Its photochemical behaviour depends on both concentration and oxygenation.…”

Section: Phototransformation Of Monohalogenophenolsmentioning

confidence: 99%

Phototransformation of halogenoaromatic derivatives in aqueous solution

Boule

Othmen

Richard

et al. 1999

International Journal of Photoenergy

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Abstract. The photochemical behaviour of monohalogeno-phenols and -anilines is highly dependent on the position of the halogen on the ring, but most often it is not significantly influenced by the nature of the halogen (Cl, Br, F). Photohydrolysis is the main reaction observed with 3-halogenated and it is almost specific. With 2-halogenated, photohydrolysis and photocontraction of the ring compete, the latter being very efficient with 2-halogeno-phenolates.The photochemical behaviour of 4-halogeno-phenols and -anilines is more complex. It depends on both concentration and oxygenation. It was rationalized when it was experimentally proved by laser flash photolysis that the first step is the formation of a carbene (in the cationic form in the case of 4-halogenoaniline). p-Benzoquinone is the product of photooxidation of 4-halogenophenols, whereas the photooxidation of 4-chloroaniline leads to 4-amino-4 -chlorodiphenylamine.Chlorohydroquinone behaves differently, the formation of the main photoproducts involving a radical mechanism.With dihalogenoanilines photohydrolysis is initially almost quantitative whatever the position of halogen atom on the ring. It occurs more easily in meta than in ortho position and in ortho than in para position. In the case of 2,4-and 2,6-dichloroanilines aminophenoxazones are formed as secondary photoproducts. This reaction involves the intermediate formation of o-benzoquinone monoimine.Several halogenoaromatic herbicides were also studied (bromoxynil, chlorpropham, propanil, diuron, linuron, chlorbromuron, MCPA). The most frequent reaction is photohydrolysis. However some other reactions such as photoreduction and photo-demethoxylation were observed. In some cases a wavelength effect was observed particularly with MCPA and halogenophenylureas.

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“…The slopes of the lines are almost the same (all in the range of 0.5~0.6). It follows that the activity of the electrode is not altered as the chlorophenols change in the process of the cyclic voltammetry [1]. Fig.…”

Section: Resultsmentioning

confidence: 93%

“…The chlorophenols (CPs) are the key intermediates by the reaction of some organic matters with chlorocarbons [1]. They are the main hazardous pollutants in the wastewater of the herbicides and the insecticides.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behaviors of Chlorophenol Aqueous Solutions at Boron-Doped Diamond Electrode

Liu¹

2011

TOMSJ

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Abstract:The electrochemical behaviors of different chlorophenols at boron-doped diamond thin film electrode were investigated. Four chlorophenols, the 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), with various number of chlorine atoms in the benzene rings, were studied by using cyclic voltammetry at different scan rates over the potential range of -1 V to 2.5 V (vs MSE). The results indicated that the reactions of the 2-CP, 2,4-DCP and 2,4,6-TCP at the diamond electrode are irreversible and controlled by diffusion, and the irreversible trend increases with the decrease of the chlorine atom number in the benzene ring. However, the activity of the boron-doped diamond film electrode does not depend on the number of the chlorine atom. Different from the three chlorophenols, fouling of the electrode occurs in PCP solutions. The possible electro-oxidation mechanisms are discussed for different chlorophenols.

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Kinetics and Mechanism of Photodegradation of Chlorophenols

Cited by 62 publications

References 233 publications

The role of indirect photolysis in limiting the persistence of crop protection products in surface waters

The role of indirect photolysis in limiting the persistence of crop protection products in surface waters

Phototransformation of halogenoaromatic derivatives in aqueous solution

Electrochemical Behaviors of Chlorophenol Aqueous Solutions at Boron-Doped Diamond Electrode

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