The effects of selected iron compounds on the sensitized photooxidation of bromacil

Riter, Ruth E.; Adams, V. Dean; George, Dennis B.; Kline, Eugene A.

doi:10.1016/0045-6535(90)90259-v

Cited by 5 publications

(2 citation statements)

References 24 publications

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“…It has been reported on silica gel that dye-sensitized photooxidation of bromacil (198) by '0 2 is significantly reduced by addition of FeO, Fe203, Fe304, or FeO(OH), which can be accounted for by an electron transfer from the excited dyes or energy transfer from '0 2 (Riter et al 1990). These compounds can become quenchers of an excited energy and catalytic sites by acting as an electron mediator.…”

Section: Metal Oxides and Hydroxidesmentioning

confidence: 99%

Reviews of Environmental Contamination and Toxicology

2004

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Section: Metal Oxides and Hydroxidesmentioning

confidence: 99%

Reviews of Environmental Contamination and Toxicology

2004

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“…Thus, the cursory explored photodegradation of bromacil and terbacil employing methylene blue (MB) or Rf as dye sensitizers, in the pH range 3-10, has shown (13) that the photolysis rates found with MB were higher at basic pH values, whereas with Rf these rates increased as the pH of the medium decreased, and were dependent on the structure of the UR pesticide. On the other hand, the photodegradation rates of the mentioned UR herbicides have been also determined in frozen aqueous solutions and on silica, in the presence of rose bengal (RB), MB or Rf (14,15). In these cases, the higher values were obtained at pH 9.1.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of the Sensitized Photodegradation of Uracil-Modeling the Fate of Related Herbicides in Aqueous Environments†

Haggi

Blasich

Dı́az

et al. 2007

Photochemistry and Photobiology

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The dye-sensitized photodegradation of uracil (UR), the parent compound of several profusely employed herbicides, has been studied as a model of their environmental fate. In order to mimic conditions frequently found in nature, aqueous solutions of UR have been irradiated with visible light in the presence of the natural sensitizer riboflavin (Rf). The results indicate that UR is photostable in acid media, but is quickly degraded in pH 7 or pH 9 solutions, where singlet molecular oxygen [O2(1Delta(g))] and, to a lesser extent, superoxide radical anion (O2*-)-both species photogenerated from triplet excited Rf, 3Rf*-participate in the photodegradation. At pH 7, UR is slowly degraded through an O2*- -mediated mechanism, whereas Rf disappears through its reaction with O2(1Delta(g)) and, in the form of 3Rf*, with UR. On the contrary, at pH 9 Rf is photoprotected through two processes: its regeneration from the formed Rf radical species-a back electron transfer that also produces O2*- -and the elimination from the medium of O2(1Delta(g)) by its reaction with UR. The overall result of the preservation of ground state Rf is the continuity of the photosensitized process and, hence, of the UR degradation. Media with higher pH values could not be employed due to the fast photodegradation of Rf. With rose bengal (RB) as photosensitizer, the rate constants found for the overall interaction between UR and the photogenerated O2(1Delta(g)) were in the range 5 x 10(5) M(-1) s(-1) (at pH 7) to 1.3 x 10(8) M(-1) s(-1) (in 1 M NaOH aqueous solution, mainly physical quenching). The maximum O2(1Delta(g)0-mediated photooxidation efficiencies with RB were reached at pH 11, where only the O2(1Delta(g)0-reactive quenching with UR was observed.

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The aqueous photolysis of triclopyr

Woodburn¹,

Batzer²,

White³

et al. 1993

Enviro Toxic and Chemistry

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The aqueous photolysis of triclopyr was examined in both pH 7‐buffered water and natural river water under artificial lights and midsummer sunlight (40°N latitude). The pseudo‐first‐order half‐lives in pH 7‐buffered water and natural river water averaged 0.5 and 1.3 d, respectively, at 25°C. Diffuse mercury lamps and midsummer sunlight produced similar rates of triclopyr decay and photoproduct distribution for a given solution. The photolysis of untreated river water produced a significantly different distribution of photoproducts compared to sterile, pH 7‐buffered water. The photolysis of triclopyr in river water generated oxamic acid as the major photoproduct and a number of other low‐molecular‐weight carboxylic acids as minor products. Photolysis in sterile, pH 7‐buffered water produced 5‐chloro‐3,6‐dihydroxy‐2‐pyridinyloxyacetic acid as the major photoproduct, with minor amounts of oxamic acid and other low‐molecular‐weight acids.

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The effects of selected iron compounds on the sensitized photooxidation of bromacil

Cited by 5 publications

References 24 publications

Reviews of Environmental Contamination and Toxicology

Reviews of Environmental Contamination and Toxicology

Kinetics and Mechanism of the Sensitized Photodegradation of Uracil-Modeling the Fate of Related Herbicides in Aqueous Environments†

The aqueous photolysis of triclopyr

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