Yields of Hydrogen Peroxide in the Decomposition of Water by Cobalt γ-Radiation. I. Effect of Bromide Ion

Sworski, Thomas J.

doi:10.1021/ja01647a058

Cited by 80 publications

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“…4 Increasing H 2 O 2 yields at lower pH have been found in aerated solutions using Br -or formic acid as radical scavengers. [6][7][8][9] However, there are contradictory reports of decreasing yields at low pH in deaerated Br -solutions. 6 There are also large contradictions in the reported data at pH >12 where the published H 2 O 2 yields range from 0.53 to 0.84 with predominance on the lower end.…”

Section: ' Introductionmentioning

confidence: 99%

“…[6][7][8][9] However, there are contradictory reports of decreasing yields at low pH in deaerated Br -solutions. 6 There are also large contradictions in the reported data at pH >12 where the published H 2 O 2 yields range from 0.53 to 0.84 with predominance on the lower end. 4 Clearly, there is no major consensus on the effects of pH on H 2 O 2 yields especially at the extremes of pH.…”

Section: ' Introductionmentioning

confidence: 99%

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Effect of pH on H₂O₂ Production in the Radiolysis of Water

Roth

LaVerne

2011

J. Phys. Chem. A

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The yields of hydrogen peroxide have been measured in the radiolysis of aqueous solutions of acrylamide, bromide, nitrate, and air in the pH range of 1-13. Hydrogen peroxide is the main stable oxidizing species formed in the radiolysis of water, and its long-term yield is found to be very sensitive to the system used in the measurements. Experiments with γ-irradiation combined with model calculations show that the primary yields of hydrogen peroxide are nearly independent of pH in the range of 2-12. Slightly higher primary yields are suggested at very low pH in particular when O(2) is present, while the yields seem to decrease at very high pH. Irradiations were performed with 5 MeV H ions, 5 MeV He ions, and 10 MeV C ions to evaluate the intratrack and homogeneous kinetic contributions to H(2)O(2) formation with different ions. Many of the trends in hydrogen peroxide yields with pH observed with γ-irradiations are observed with irradiation by the heavy ions. The lower yields of radicals in the homogeneous phase with the heavier ions tend to minimize the effects of radicals on the hydrogen peroxide yields at long times.

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Section: ' Introductionmentioning

confidence: 99%

Section: ' Introductionmentioning

confidence: 99%

Effect of pH on H₂O₂ Production in the Radiolysis of Water

Roth

LaVerne

2011

J. Phys. Chem. A

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“…[I21 OH + Br---, Br + OHHowever, with aerated broinide solutions the initial yield of H2Oz is dependent on the concentration of the bromide ion (28,29) and the degree of this dependency is related to the 1.e.t. of the radiation (30).…”

Section: Hz02 In Irradiated Solutionsmentioning

confidence: 99%

A L.E.T. INDEPENDENT DOSIMETER BASED ON THE CHEMILUMINESCENT DETERMINATION OF H₂O₂

Armstrong¹,

Humphreys²

1965

Can. J. Chem.

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A sensitive method for the determination of Hz02 based on the copper-catalyzed chemilu~ninescent reaction between luminol and H202 has been developed. The integral luminescence measured with a modified spec:trophotofluorometer was found to increase linearly with concentration for 3 X low8 t o 1.5 X ill H202 solutions. This method was applied to the determination of Hz02 formed in irradiated water and it was shown t h a t this system may be used as a dosimeter in the range 30 t o 3 000 rads. The following values were obtained for the initial H20? yields: G(H202) = 1.22 f 0.07 for =OCo y-radiation, 1.28 f 0.09 for 250 kVcp (105 keV effective) X-radiation and 1.31 f 0.04 for 14 MeV neutrons. These results and those of other workers demonstrate that the initial yield of Hz02 in aerated water increases only by about 15% for a n increase in radiation 1.e.t. of 0.02 to 14 ev/A.

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“…This effect (19,20,211, which has been extensively studied experimentally and theoretically, is due to competition between the scavenging process and the recombination process during the time in which the latter is proceeding a t a significant rate.…”

Section: The Effect Of Scavenger Concentrationmentioning

confidence: 99%

The Kinetics of Radical Reactions in the Tracks of Fast Electrons. A Detailed Study of the Samuel–magee Model for the Radiation Chemistry of Water

Dyne¹,

Kennedy²

1958

Can. J. Chem.

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The kinetic behavior of a 7-ray spur produced in water, having H and OH radicals distributed spatially in the manner suggested by Samuel and Magee, has been studied using an electronic computer. The variation in yield of the molecular products Hz, H20Z, and H?O with rate constants, diffusion constants, and spur size has been obtained. The model gives agreement with experiment choosing spurs with a small "radius" of the order of 10 A. On simple assumptions, however, the modcl predicts no difference in the molecular yields between heavy and light water and no isotopic separation in the formation of molecular hydrogen from isotopically enriched light water. Various special assumptions needed to give agreement with experiment for thcse isotope effects are discussed. The observed isotopicseparation in theformation of molecular hydrogen is attributed to the preferential dissociation of an H atom from an excited HDO molecule. I t is found that the yield of molecular hydrogen is less sensitive t o the presence of scavengers than the yield of hydrogel1 peroxide. INTRODUCTIONThe products of the radiation decomposition of water are of two types, free radicals and molecules, and it is generally supposed that the molecular products (hydrogen and hydrogen peroxide) are formed by recombination of free radicals (H and OH) in regions of high radical concentration. In the model of this process proposed by Samuel and Magee (I) it was suggested that the radicals were formed by the dissociation of excited water molecules. Conseq~iently, both species of radicals have initially a similar spatial distribution; some of these radicals recombine t o give molecular products, others escape by diffusion into the bulk of the solution where they can be detected by their reactions as radicals. Several variations of this model are discussed by Dewhurst, Samuel, and Magee (2).While this model has been widely accepted for the interpretation of the radiation chemistry of water no detailed study of its properties has been made in which the recombination of both reacting species (H and OH) is treated. As the kinetics of recombination and diffusion cannot be handled analytically the majority of calculations hitherto have been performed on a simplified version, a "one radical" model in which the one species has the "average" properties of H and OH. These calculations have shown that the model explains many of the features of the radiation decoinposition of water and on this pragmatic basis the model has been accepted.We have surmountecl the main obstacle to the study of a two-radical model, the intractable nature of the equations, by programming the problem for numerical solution on the Chalk River Datatron Computer, and this paper presents the results of these calculations. A secoild, equally serious, obstacle remains and this is our lack of kno~vledge about the rate constants and diffusioil constants and other parameters of the system. We have, accordingly, adopted an approach which is essentially the converse of that of experimental chemical...

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Yields of Hydrogen Peroxide in the Decomposition of Water by Cobalt γ-Radiation. I. Effect of Bromide Ion

Cited by 80 publications

References 0 publications

Effect of pH on H₂O₂ Production in the Radiolysis of Water

Effect of pH on H₂O₂ Production in the Radiolysis of Water

A L.E.T. INDEPENDENT DOSIMETER BASED ON THE CHEMILUMINESCENT DETERMINATION OF H₂O₂

The Kinetics of Radical Reactions in the Tracks of Fast Electrons. A Detailed Study of the Samuel–magee Model for the Radiation Chemistry of Water

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Yields of Hydrogen Peroxide in the Decomposition of Water by Cobalt γ-Radiation. I. Effect of Bromide Ion

Cited by 80 publications

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Effect of pH on H2O2 Production in the Radiolysis of Water

Effect of pH on H2O2 Production in the Radiolysis of Water

A L.E.T. INDEPENDENT DOSIMETER BASED ON THE CHEMILUMINESCENT DETERMINATION OF H2O2

The Kinetics of Radical Reactions in the Tracks of Fast Electrons. A Detailed Study of the Samuel–magee Model for the Radiation Chemistry of Water

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Effect of pH on H₂O₂ Production in the Radiolysis of Water

Effect of pH on H₂O₂ Production in the Radiolysis of Water

A L.E.T. INDEPENDENT DOSIMETER BASED ON THE CHEMILUMINESCENT DETERMINATION OF H₂O₂