Buffering of pH conditions in sodium bentonite

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

A bentonite buffer is a part of the engineering barrier system of the geological disposal concept for spent nuclear fuel in Finland. The chemical conditions in the bentonite porewater determine the solubility, speciation and diffusion/sorption behaviour of the radionuclides in the bentonite. The OH-groups on the edge sites of the montmorillonite, the main component of bentonite, can buffer the pH conditions especially in the case that the buffering capacity of the accessory minerals is small. In this work, the pH conditions created by the interaction of sodium montmorillonite and an acetate buffer solution were studied experimentally in batch experiments and in compacted sodium montmorillonite. In the experiment with the compacted sample, the ends of an 18.4 mm long cylinder were exposed to an external solution of 0.3 M NaCl and 0.1 M acetate adjusted to pH 5 with NaOH. The effects were monitored by measuring the pH in the montmorillonite sample at 5 mm and 9.2 mm from the solution-montmorillonite interface as a function of time. The batch experiment was modelled considering the surface reactions of montmorillonite and the dissolution reactions of calcite and the added constituents to explain the observed phenomena.
Original languageEnglish
Title of host publicationMRS Proceedings
Subtitle of host publicationSymposium NW – Scientific Basis for Nuclear Waste Management XXXV
PublisherMaterials research society
Pages317-321
ISBN (Print)978-1-6274-8264-6
DOIs
Publication statusPublished - 2012
MoE publication typeA4 Article in a conference publication
EventMRS Spring Meeting - San Francisco, CA, United States
Duration: 9 Apr 201213 Apr 2012

Publication series

NameMaterials Research Society MRS
PublisherMaterials Research Society
Volume1475

Conference

ConferenceMRS Spring Meeting
CountryUnited States
CitySan Francisco, CA
Period9/04/1213/04/12

Fingerprint

Bentonite
Sodium
Buffers
Acetates
Calcium Carbonate
Experiments
Spent fuels
Accessories
Surface reactions
Nuclear fuels
Radioisotopes
Minerals
Sorption
Dissolution
Solubility

Cite this

Pulkkanen, V-M., Itälä, A., & Muurinen, A. (2012). Buffering of pH conditions in sodium bentonite. In MRS Proceedings: Symposium NW – Scientific Basis for Nuclear Waste Management XXXV (pp. 317-321). Materials research society. Materials Research Society MRS, Vol.. 1475 https://doi.org/10.1557/opl.2012.593
Pulkkanen, Veli-Matti ; Itälä, Aku ; Muurinen, Arto. / Buffering of pH conditions in sodium bentonite. MRS Proceedings: Symposium NW – Scientific Basis for Nuclear Waste Management XXXV. Materials research society, 2012. pp. 317-321 (Materials Research Society MRS, Vol. 1475).
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Pulkkanen, V-M, Itälä, A & Muurinen, A 2012, Buffering of pH conditions in sodium bentonite. in MRS Proceedings: Symposium NW – Scientific Basis for Nuclear Waste Management XXXV. Materials research society, Materials Research Society MRS, vol. 1475, pp. 317-321, MRS Spring Meeting, San Francisco, CA, United States, 9/04/12. https://doi.org/10.1557/opl.2012.593

Buffering of pH conditions in sodium bentonite. / Pulkkanen, Veli-Matti; Itälä, Aku; Muurinen, Arto.

MRS Proceedings: Symposium NW – Scientific Basis for Nuclear Waste Management XXXV. Materials research society, 2012. p. 317-321 (Materials Research Society MRS, Vol. 1475).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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Pulkkanen V-M, Itälä A, Muurinen A. Buffering of pH conditions in sodium bentonite. In MRS Proceedings: Symposium NW – Scientific Basis for Nuclear Waste Management XXXV. Materials research society. 2012. p. 317-321. (Materials Research Society MRS, Vol. 1475). https://doi.org/10.1557/opl.2012.593