CO2 effect on the pH of compacted bentonite buffer on the laboratory scale

Aku Itälä (Corresponding Author), Joonas Järvinen, A. Muurinen

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

Disposal of Finnish spent nuclear fuel is planned to be based on the KBS-3 repository concept. The role of the bentonite buffer in this concept is essential, and thus the behaviour of the bentonite has to be known. The experiments in this paper concentrated on providing information about the effects of carbon dioxide CO2(g) partial pressure on compacted sodium bentonite, giving an insight into the buffering capacity. The experimental setup consisted of a hermetic box which had a CO2-adjusted atmosphere, and the bentonite was in contact with this atmosphere through water reservoirs. The results indicated that it is possible to measure online the changing pH in the porewater inside compacted bentonite using IrOx electrodes. It was found that the pH fell if the CO2 partial pressure increased above atmospheric conditions. The experimental results indicated a greater fall in pH than in our model in the test cases where CO2 was present. The pH in the experiment with 0 PCO2 remained nearly constant throughout the 5 month period. On the other hand, the pH dropped to near 6 with 0.3 PCO2 and to 5.5 with 1 PCO2 .
Original languageEnglish
Pages (from-to)277-283
Number of pages6
JournalClay Minerals
Volume48
Issue number2
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed

Fingerprint

Bentonite
bentonite
Buffers
partial pressure
Partial pressure
atmosphere
Spent fuels
Nuclear fuels
buffering
Carbon Dioxide
repository
porewater
electrode
carbon dioxide
experiment
Sodium
Experiments
sodium
laboratory
effect

Keywords

  • alteration
  • bentonite
  • buffer
  • carbon dioxide
  • compaction
  • ph

Cite this

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title = "CO2 effect on the pH of compacted bentonite buffer on the laboratory scale",
abstract = "Disposal of Finnish spent nuclear fuel is planned to be based on the KBS-3 repository concept. The role of the bentonite buffer in this concept is essential, and thus the behaviour of the bentonite has to be known. The experiments in this paper concentrated on providing information about the effects of carbon dioxide CO2(g) partial pressure on compacted sodium bentonite, giving an insight into the buffering capacity. The experimental setup consisted of a hermetic box which had a CO2-adjusted atmosphere, and the bentonite was in contact with this atmosphere through water reservoirs. The results indicated that it is possible to measure online the changing pH in the porewater inside compacted bentonite using IrOx electrodes. It was found that the pH fell if the CO2 partial pressure increased above atmospheric conditions. The experimental results indicated a greater fall in pH than in our model in the test cases where CO2 was present. The pH in the experiment with 0 PCO2 remained nearly constant throughout the 5 month period. On the other hand, the pH dropped to near 6 with 0.3 PCO2 and to 5.5 with 1 PCO2 .",
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author = "Aku It{\"a}l{\"a} and Joonas J{\"a}rvinen and A. Muurinen",
year = "2013",
doi = "10.1180/claymin.2013.048.2.09",
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volume = "48",
pages = "277--283",
journal = "Clay Minerals",
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CO2 effect on the pH of compacted bentonite buffer on the laboratory scale. / Itälä, Aku (Corresponding Author); Järvinen, Joonas; Muurinen, A.

In: Clay Minerals, Vol. 48, No. 2, 2013, p. 277-283.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - CO2 effect on the pH of compacted bentonite buffer on the laboratory scale

AU - Itälä, Aku

AU - Järvinen, Joonas

AU - Muurinen, A.

PY - 2013

Y1 - 2013

N2 - Disposal of Finnish spent nuclear fuel is planned to be based on the KBS-3 repository concept. The role of the bentonite buffer in this concept is essential, and thus the behaviour of the bentonite has to be known. The experiments in this paper concentrated on providing information about the effects of carbon dioxide CO2(g) partial pressure on compacted sodium bentonite, giving an insight into the buffering capacity. The experimental setup consisted of a hermetic box which had a CO2-adjusted atmosphere, and the bentonite was in contact with this atmosphere through water reservoirs. The results indicated that it is possible to measure online the changing pH in the porewater inside compacted bentonite using IrOx electrodes. It was found that the pH fell if the CO2 partial pressure increased above atmospheric conditions. The experimental results indicated a greater fall in pH than in our model in the test cases where CO2 was present. The pH in the experiment with 0 PCO2 remained nearly constant throughout the 5 month period. On the other hand, the pH dropped to near 6 with 0.3 PCO2 and to 5.5 with 1 PCO2 .

AB - Disposal of Finnish spent nuclear fuel is planned to be based on the KBS-3 repository concept. The role of the bentonite buffer in this concept is essential, and thus the behaviour of the bentonite has to be known. The experiments in this paper concentrated on providing information about the effects of carbon dioxide CO2(g) partial pressure on compacted sodium bentonite, giving an insight into the buffering capacity. The experimental setup consisted of a hermetic box which had a CO2-adjusted atmosphere, and the bentonite was in contact with this atmosphere through water reservoirs. The results indicated that it is possible to measure online the changing pH in the porewater inside compacted bentonite using IrOx electrodes. It was found that the pH fell if the CO2 partial pressure increased above atmospheric conditions. The experimental results indicated a greater fall in pH than in our model in the test cases where CO2 was present. The pH in the experiment with 0 PCO2 remained nearly constant throughout the 5 month period. On the other hand, the pH dropped to near 6 with 0.3 PCO2 and to 5.5 with 1 PCO2 .

KW - alteration

KW - bentonite

KW - buffer

KW - carbon dioxide

KW - compaction

KW - ph

U2 - 10.1180/claymin.2013.048.2.09

DO - 10.1180/claymin.2013.048.2.09

M3 - Article

VL - 48

SP - 277

EP - 283

JO - Clay Minerals

JF - Clay Minerals

SN - 0009-8558

IS - 2

ER -