Sorption and diffusion of selenium oxyanions in granitic rock

Ikonen, Jussi; Voutilainen, Mikko; Söderlund, Mervi; Jokelainen, Lalli; Siitari-Kauppi, Marja; Martin, Andrew J.

doi:10.1016/j.jconhyd.2016.08.003

Cited by 31 publications

(21 citation statements)

References 42 publications

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“…Se is considered as an important radionuclide of interest as it is present in radioactive wastes and spent nuclear fuel. 7 Specifically, Se 79 isotope formed by nuclear fission reactions is the main radioisotope of Se found in nuclear wastes. 7 The solubility and mobility of this element depends to a great extent on its different oxidation states [selenate (Se VI ), selenite (Se IV ), elemental selenium (Se 0 ) and selenide (Se −II )].…”

Section: Introductionmentioning

confidence: 99%

“…7 Specifically, Se 79 isotope formed by nuclear fission reactions is the main radioisotope of Se found in nuclear wastes. 7 The solubility and mobility of this element depends to a great extent on its different oxidation states [selenate (Se VI ), selenite (Se IV ), elemental selenium (Se 0 ) and selenide (Se −II )]. In contrast to toxic and highly reactive Se oxyanions (Se VI and Se IV ), Se 0 and methyl selenide forms are basically insoluble and less biologically available.…”

Section: Introductionmentioning

confidence: 99%

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Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species

Ruiz-Fresneda

Eswayah

Romero-González

et al. 2020

Environ. Sci.: Nano

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species

Ruiz-Fresneda

Eswayah

Romero-González

et al. 2020

Environ. Sci.: Nano

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“…The values for porosity and the effective diffusion coefficient of Kuru Grey granite were selected according to previously determined values, i.e. 0.47% (Jokelainen et al, 2009) and 8 × 10 −13 m 2 /s (Ikonen et al, 2016), respectively.…”

Section: Analytical Modelingmentioning

confidence: 99%

Neptunium(V) transport in granitic rock: A laboratory scale study on the influence of bentonite colloids

Elo

Hölttä

Kekäläinen

et al. 2019

Applied Geochemistry

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In the present study neptunium(V) uptake by crystalline granitic rock (Kuru Grey granite) and the role of stable and mobile bentonite colloids (MX-80) on the migration of neptunium(V) was investigated. Two different experimental setups were utilized, batch-type experiments under stagnant conditions and column experiments under flowing water conditions. The uptake of 10 −6 M neptunium(V) by 40 g/L crushed granite in 10 mM NaClO 4 was found to be pH-dependent, whereas neptunium(V) uptake by MX-80 bentonite colloids (0.08-0.8 g/ L) was pH-independent up to a pH-value of approximately 11. Column experiments were conducted in the presence and absence of colloids at two pH values (pH = 8 and 10) and two flow rates (0.3 and 0.8 mL/h) in 10 mM NaClO 4. The injected neptunium(V) concentration was 2 × 10 −4 M and the colloid concentration ranged from 0.08 to 0.32 g/L. The properties of the flow field in the columns were investigated with a conservative chloride tracer, at the same two flow rates of 0.8 and 0.3 mL/h. The resulting breakthrough curves were modeled using the analytical solution of advection-matrix diffusion equation. A tailing of neptunium(V) breakthrough curves in comparison to the conservative tracer was observed, which could be explained by a slightly higher retardation of neptunium(V) in the column caused by sorption on the granite. The sorption was in general lower at pH 8 than at pH 10. In addition, the tailing was almost identical in the absence and presence of MX-80 bentonite colloids, implying that the influence of colloids on the neptunium(V) mobility is almost negligible.

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“…The TDRW method has been used to study the effect of centimeter-scale structural heterogeneities on diffusion in various cases [36,37,40,49]. The TDRW method has also been used to model transport in fractured media [28,29] and has been shown to be a powerful tool for analyzing results of in situ and laboratory experiments, especially when initial or boundary conditions are complex [1,15,16,49]. Previously, Dentz et al [9] modified the TDRW method to include sorption by using specific functions for trapping frequency and number of trapping events.…”

Section: Introductionmentioning

confidence: 99%

Modeling mass transfer in fracture flows with the time domain-random walk method

2019

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The time domain-random walk method was developed further for simulating mass transfer in fracture flows together with matrix diffusion in surrounding porous media. Specifically, a time domain-random walk scheme was developed for numerically approximating solutions of the advection-diffusion equation when the diffusion coefficient exhibits significant spatial variation or even discontinuities. The proposed scheme relies on second-order accurate, central-difference approximations of the advective and diffusive fluxes. The scheme was verified by comparing simulated results against analytical solutions in flow configurations involving a rectangular channel connected on one side with a porous matrix. Simulations with several flow rates, diffusion coefficients, and matrix porosities indicate good agreement between the numerical approximations and analytical solutions.

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Sorption and diffusion of selenium oxyanions in granitic rock

Cited by 31 publications

References 42 publications

Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species

Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species

Neptunium(V) transport in granitic rock: A laboratory scale study on the influence of bentonite colloids

Modeling mass transfer in fracture flows with the time domain-random walk method

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Sorption and diffusion of selenium oxyanions in granitic rock

Cited by 31 publications

References 42 publications

Chemical and structural characterization of SeIV biotransformations by Stenotrophomonas bentonitica into Se0 nanostructures and volatiles Se species

Chemical and structural characterization of SeIV biotransformations by Stenotrophomonas bentonitica into Se0 nanostructures and volatiles Se species

Neptunium(V) transport in granitic rock: A laboratory scale study on the influence of bentonite colloids

Modeling mass transfer in fracture flows with the time domain-random walk method

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Product

Resources

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Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species

Chemical and structural characterization of Se^IV biotransformations by Stenotrophomonas bentonitica into Se⁰ nanostructures and volatiles Se species