Measuring the effective diffusion coefficient of dissolved hydrogen in saturated Boom Clay

Jacops, Elke; Wouters, Katinka; Volckaert, Guido; Moors, Hugo; Maes, N.; Bruggeman, Christophe; Swennen, Rudy; Littke, Ralf

doi:10.1016/j.apgeochem.2015.05.022

Cited by 35 publications

(27 citation statements)

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“…In case of hydrogen, Jacops et al [24] have shown that diffusion experiments with hydrogen often suffer from microbial activity: here methanogenic microbes convert H 2 into CH 4 , making the accurate determination of diffusion coefficients impossible [24]. Similar observations have been reported by Vinsot et al [25].…”

Section: Introductionsupporting

confidence: 71%

“…By using this approach, the diffusion coefficient of, for instance, H 2 (which is difficult to measure due to microbial activity [24]), can be estimated based on its molecular size. But note that the diffusion coefficient for H 2 was (due to experimental difficulties) measured for only one sample; hence the correction factor might be only an estimate.…”

Section: How To Estimate Gas Diffusion Coefficients As a Function Of mentioning

confidence: 99%

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The Dependency of Diffusion Coefficients and Geometric Factor on the Size of the Diffusing Molecule: Observations for Different Clay-Based Materials

et al. 2017

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In order to investigate in more detail the relation between the size of diffusing molecules and their diffusion coefficients (and geometric factors), diffusion experiments with gases of different size and tritiated water (HTO) have been performed on different clayey samples (Boom Clay, Eigenbilzen Sands, Opalinus Clay, Callovo-Oxfordian Clay, and bentonite with different dry densities). We observed that, for unreactive gases in clayey materials, the effective diffusion coefficient varies with the size of the diffusing molecule and this variation can be described by an exponential or a power law function. The variation of the geometric factor can also be described by an exponential function. The observed experimental relations can be used to estimate diffusion coefficients; by measuring experimentally in clay the effective diffusion coefficient of two unreactive dissolved gases with a different size, the diffusion coefficients of other dissolved gases (with a size in between the two measured gases) can be estimated by using the fitted exponential relationship.

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Section: Introductionsupporting

confidence: 71%

Section: How To Estimate Gas Diffusion Coefficients As a Function Of mentioning

confidence: 99%

The Dependency of Diffusion Coefficients and Geometric Factor on the Size of the Diffusing Molecule: Observations for Different Clay-Based Materials

et al. 2017

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“…However, measuring the diffusion coefficient of hydrogen with a high degree of accuracy is difficult as hydrogenair mixtures have a low explosion limit and H 2 easily leaks from the experimental set-up. But the major problem is the microbial conversion of H 2 into CH 4 by methanogenic bacteria (Jacops et al 2015). Owing to these experimental difficulties and the current lack of accurate diffusion data for hydrogen, the diffusion coefficient of helium is often used as a surrogate for the diffusion coefficient of hydrogen.…”

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confidence: 99%

Measuring diffusion coefficients of dissolved He and Ar in three potential clay host formations: Boom Clay, Callovo-Oxfordian Clay and Opalinus Clay

Jacops

Maes

Bruggeman

2016

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For the long-term management of high-and intermediate-level radioactive waste and/ or spent fuel, many countries prefer disposal in a geological repository. In Belgium, Switzerland and France, argillaceous formations are being explored as potential host formations for this purpose. In this context, knowledge of the diffusion coefficient of He is relevant within two research areas: first, diffusion coefficients are used in safety calculations to evaluate the balance between gas generation (mainly H 2 ) and gas dissipation; and, second, the diffusion coefficients of He and Ar are needed in the diffusion models of natural tracers. Owing to the lack of data on the diffusion coefficients of He and Ar for the different clay host formations, diffusion experiments with dissolved He and Ar were performed on Boom Clay, Opalinus Clay and Callovo-Oxfordian Clay. Samples were confined in a diffusion cell, and diffusion coefficients were measured by using the double throughdiffusion technique. The diffusion coefficients (D p or D pore ) for He in Boom Clay, Callovo-Oxfordian Clay and Opalinus Clay are 12.6 × 10 210 , 4.51 × 10 210 and 7.13 × 10 210 m 2 s 21 , respectively. The diffusion coefficients for Ar in Boom Clay, Callovo-Oxfordian Clay and Opalinus Clay are 18.6 × 10 211 , 4.06 × 10 211 and 3.65 × 10 211 m 2 s 21 , respectively.

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“…Also hydrogen gas, which entered the experiments during manipulations in the glove box, can serve as an electron donor. Without rigorous sterilisation, hydrogen gas used in diffusion experiments with Boom Clay from Belgium induced methane production by methanogenic organisms in the Boom Clay samples (Jacops et al, 2015) In our experiments, only traces (<0.12 mM) of dissolved sulphide were detected at the end of the experiments, representing less than 1% of the initially dissolved S. The sulphide, produced by sulphate reduction, could react with iron phases forming iron sulphides. Unfortunately, our data do not provide information about the change in the composition of solids.…”

Section: Time Evolution Of Solution Composition In the Dilution Expermentioning

confidence: 88%

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

Behrends

Veen

Hoving

et al. 2016

Netherlands Journal of Geosciences

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The Rupel Clay member in the Netherlands largely corresponds to the Boom Formation in Belgium, and this marine, clay-rich deposit is a potential candidate to host radioactive waste disposal facilities. Prediction of the speciation of radionuclides in Rupel Clay pore water and their retardation by interactions with Rupel Clay components requires knowledge about the composition of Rupel Clay pore water, the inventory of reactive solids and understanding of interactions between Rupel Clay and pore water. Here, we studied Rupel Clay material which was obtained from cores collected in the province of Zeeland, the Netherlands, and from drilling cuttings retrieved from a drilling in the province of Limburg, the Netherlands. Pore water was obtained by mechanical squeezing of Rupel Clay material from Zeeland. Additionally, anaerobic dilution experiments were performed in which the clay material was suspended with demineralised water or a 0.1 M NaHCO 3 solution. Solid-phase characterisation included determination of carbon, nitrogen and sulphur contents, measurement of cation exchange capacity (CEC) and sequential extraction of iron phases.In contrast to the pore water in Belgian Boom Clay, pore water collected from the location in Zeeland has a higher salinity, with chloride concentrations corresponding to 70-96% of those in seawater. The high chloride concentrations most likely result from the intrusion of ions from saline waters above the Rupel Clay in Zeeland. Cation exchange during salinisation might account for the observed deficit of marine cations (Na, K, Mg) and excess of Ca concentrations, in comparison with seawater. The measured CEC values at both locations in the Netherlands vary between 7 and 35 meq (100 g) −1 and are, for most samples, in the range reported for Boom Clay in Belgium (7-30 meq (100 g) −1 ).Pore water and solid-phase composition indicate that Rupel Clay from Zeeland has been affected by oxidation of pyrite or other Fe(II)-containing solids. When coupled to the dissolution of calcium carbonates, oxidation of pyrite can account for the elevated sulphate and calcium concentrations measured in some of the pore waters. The relatively low concentrations of pyrite, organic carbon and calcite in the Rupel Clay in Zeeland, in comparison to Limburg, might be an indicator for an oxidation event. Higher contents of dithionite-extractable Fe in Rupel Clay in Zeeland (0.7-2.6 mg Fe / g clay) than in Limburg (0.4-0.5 mg Fe / g clay) might also be a consequence of the oxidation of Fe(II) minerals. Oxidation in the past could have accompanied partial erosion of Rupel Clay in Zeeland before deposition of the Breda Formation. However, indications are given that oxidation occurred in some of the pore waters after sampling and that partial oxidation of the cores during storage cannot be excluded. Results from dilution experiments substantiate the influence of equilibration with calcium carbonates on pore water composition. Furthermore, removal of dissolved sulphate upon interaction with Rupel Clay has been...

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Measuring the effective diffusion coefficient of dissolved hydrogen in saturated Boom Clay

Cited by 35 publications

References 35 publications

The Dependency of Diffusion Coefficients and Geometric Factor on the Size of the Diffusing Molecule: Observations for Different Clay-Based Materials

The Dependency of Diffusion Coefficients and Geometric Factor on the Size of the Diffusing Molecule: Observations for Different Clay-Based Materials

Measuring diffusion coefficients of dissolved He and Ar in three potential clay host formations: Boom Clay, Callovo-Oxfordian Clay and Opalinus Clay

First assessment of the pore water composition of Rupel Clay in the Netherlands and the characterisation of its reactive solids

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