The G-values of the primary species in 0.4 mol dm-3 H2SO4 irradiated at 300°C

Elliot, A. John; Ouellette, Denis C.; Reid, David L.; McCracken, David R.

doi:10.1016/1359-0197(89)90278-6

Cited by 3 publications

(6 citation statements)

References 15 publications

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“…6, our computed results generally agree very well with experimental yields reported in the literature. 1,44,51,62,64 They are also in good accord with recent diffusion-kinetic model calculations in irradiated acidic water (data not shown here). 65 Of particular note is the remarkable agreement found between our calculated g-values for OH and H and those measured by Katsumura et al 51 up to 250 1C.…”

Section: Resultssupporting

confidence: 92%

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350 °C: a Monte-Carlo simulation study

Sanguanmith

Muroya

Tippayamontri

et al. 2011

Phys. Chem. Chem. Phys.

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Monte-Carlo simulations of the radiolysis of the ferrous sulfate (Fricke) dosimeter with low-linear energy transfer (LET) radiation (such as (60)Co γ-rays or fast electrons) have been performed as a function of temperature from 25 to 350 °C. The predicted yields of Fe(2+) oxidation are found to increase with increasing temperature up to ∼100-150 °C, and then tend to remain essentially constant at higher temperatures, in very good agreement with experiment. By using a simple method based on the direct application of the stoichiometric relationship that exists between the ferric ion yields so obtained G(Fe(3+)) and the sum {3 [g(e(-)(aq) + H˙) + g(HO(2)˙)] + g(˙OH) + 2 g(H(2)O(2))}, where g(e(-)(aq) + H˙), g(HO(2)˙), g(˙OH), and g(H(2)O(2)) are the primary radical and molecular yields of the radiolysis of deaerated 0.4 M H(2)SO(4) aqueous solutions, the lifetime (τ(s)) of the spur and its temperature dependence have been determined. In the spirit of the spur model, τ(s) is an important indicator for overlapping spurs, giving the time required for the changeover from nonhomogeneous spur kinetics to homogeneous kinetics in the bulk solution. The calculations show that τ(s) decreases by about an order of magnitude over the 25-350 °C temperature range, going from ∼4.2 × 10(-7) s at 25 °C to ∼5.7 × 10(-8) s at 350 °C. This decrease in τ(s) with increasing temperature mainly originates from the quicker diffusion of the individual species involved. Moreover, the observed dependence of G(Fe(3+)) on temperature largely reflects the influence of temperature upon the primary free-radical product yields of the radiolysis, especially the yield of H˙ atoms. Above ∼200-250 °C, the more and more pronounced intervention of the reaction of H˙ atoms with water also contributes to the variation of G(Fe(3+)), which may decrease or increase slightly, depending on the choice made for the rate constant of this reaction. All calculations reported herein use the radiolysis database of Elliot (Atomic Energy of Canada Limited) and Bartels (University of Notre Dame) that contains all the best currently available information on the rate constants, reaction mechanisms, and g-values in the range 20 to 350 °C.

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Section: Resultssupporting

confidence: 92%

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350 °C: a Monte-Carlo simulation study

Sanguanmith

Muroya

Tippayamontri

et al. 2011

Phys. Chem. Chem. Phys.

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“…Also shown in Fig. 8 is the G(H2) obtained in an earlier study of 0.1 rnol kg-' methanol in 0.4 rnol kg-' sulphuric acid (5). The increase of G(H2) with temperature for the 0.4 rnol kg-' sulphuric acid solution is less than with the rnol kg-' perchloric acid.…”

Section: Discussion (A) Estimation Of G(h2)mentioning

confidence: 81%

“…It is most likely that the hydrolysis of either Cd+ , CdZ2+, or c d O (reactions [6] and [15] 35)gives rise to the excess hydrogen (reactions [16] or [17] followed by [4]). In the two solutions where acetone was used as the hydrated electron scavenger, the radical, (CH3)2COH, formed in reactions [5] and [7] appears to be responsible for the increase in the hydrogen yield above 200°C.…”

Section: Discussion (A) Estimation Of G(h2)mentioning

confidence: 99%

“…This suggests a chain reaction must be occurring, but, unfortunately, under the present experimental arrangement the dose rate cannot be varied to screen for a chain reaction. One possible mechanism is the thermally induced reaction [19] to form atomic hydrogen heat [19] (CH3)2COH u (CH3)2C=0 + H followed by reaction [5] to form the excess molecular hydrogen and another (CH3),COH radical to propagate the chain. When methanol is present, reaction [4] produces some extra molecular hydrogen but, as .CH20H does not thermally decompose at these temperatures, the chain reaction cannot occur.…”

Section: Discussion (A) Estimation Of G(h2)mentioning

confidence: 99%

“…G(H2) as a function of temperature as measured from degassed solutions containing: lo-' mol kg-' methanol, mol kg-' HC1O4 (W); value estimated at 300°C ( 0 ) ; lo-' mol kg-' methanol, lo-' mol kg-' KH2P04, pH adjusted to 2.4 at 25°C (A); lo-' mol kg-' methanol, 0.4 mol kg-' H2SO4 (V)(5).…”

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g-Values for γ-irradiated water as a function of temperature

Elliot¹,

Chenier²,

Ouellette³

1990

Can. J. Chem.

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The g-values of primary species formed in the γ-radiolysis of water have been estimated for the temperature range 25–300 °C. The g-values for the hydrated electron, the hydroxyl radical, and molecular hydrogen all increase approximately 50% over this temperature range. The g-values for the minor products, hydrogen peroxide and atomic hydrogen, probably also increase with temperature; however, there is evidence from some of the experimental data which suggests that these g-values may slightly decrease with increasing temperature. Keywords: radiolysis, g-values, temperature dependence.

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Diffusion-kinetic modeling of the electron radiolysis of water at elevated temperatures

LaVerne¹,

Pimblott²

1993

J. Phys. Chem.

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The G-values of the primary species in 0.4 mol dm-3 H2SO4 irradiated at 300°C

Cited by 3 publications

References 15 publications

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350 °C: a Monte-Carlo simulation study

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350 °C: a Monte-Carlo simulation study

g-Values for γ-irradiated water as a function of temperature

Diffusion-kinetic modeling of the electron radiolysis of water at elevated temperatures

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