Gas-bentonite interactions: Towards a better understanding of gas dynamics in Engineered Barrier Systems

Tomonaga, Yama; Wersin, Paul; Rufer, Daniel; Pastina, Barbara; Koho, Petri; Ville, Heino; Kipfer, Rolf (2022). Gas-bentonite interactions: Towards a better understanding of gas dynamics in Engineered Barrier Systems. Applied geochemistry, 138, p. 105205. Elsevier 10.1016/j.apgeochem.2022.105205

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Bentonite is a common backfill material used in Engineered Barrier Systems (EBS) for radioactive waste disposal. Its thermal, hydraulic, and chemical properties have been extensively studied. However, empirical evidence on the interactions with the free gas phase present in its pore space under conditions close to those prevailing in deep geological repositories (i.e., exposure to multiple gas species at temperature and humidity conditions close to those of freshly backfilled EBS) is scarce. This limits the prediction/assessment of the evolution of the gas composition in EBS. Here we present the outcome of laboratory experiments targeting such gas-bentonite interactions using two different types of bentonite (Italian bentonite; Wyoming bentonite) being exposed to atmospheric air in sealed stainless-steel vessels. The results indicate that gas sorption on bentonite can occur at repository-like conditions and is likely to play a significant role in the overall gas dynamics in the backfill of EBS. Drying of both bentonites was shown to partly re-activate their CO2 sorption capacity during a subsequent re-hydration phase. Furthermore, the grinding of Wyoming bentonite resulted in the generation of new pyrite surfaces that significantly enhanced O2 removal from the free gas phase by oxidation. Our initial investigations call for more systematic and extensive series of laboratory experiments in order to quantitatively constrain the different processes involved in gas-bentonite interactions.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Applied Rock-Water-Interaction

UniBE Contributor:

Wersin, Paul and Rufer, Daniel

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0883-2927

Publisher:

Elsevier

Language:

English

Submitter:

Daniel Rufer

Date Deposited:

23 Mar 2022 16:04

Last Modified:

02 May 2022 16:40

Publisher DOI:

10.1016/j.apgeochem.2022.105205

BORIS DOI:

10.48350/167667

URI:

https://boris.unibe.ch/id/eprint/167667

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