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Design and Preliminary Results of Redox Capacity Measurements of Granitic Rocks and Minerals

Published online by Cambridge University Press:  28 February 2011

Veijo O. Pirhonen ,
Petteri Pitkänen ,
Jukka Takala  and
Esko Arilahti
Veijo O. Pirhonen
Affiliation:
Technical Research Centre of Finland, Geotechnical Laboratory, P.O. BOX 108, SF-02151 Espoo, Finland.
Petteri Pitkänen
Affiliation:
Technical Research Centre of Finland, Geotechnical Laboratory, P.O. BOX 108, SF-02151 Espoo, Finland.
Jukka Takala
Affiliation:
Technical Research Centre of Finland, Geotechnical Laboratory, P.O. BOX 108, SF-02151 Espoo, Finland.
Esko Arilahti
Affiliation:
Metal Laboratory, P.O. Box 26, SF-02151 Espoo, Finland.
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Abstract

A procedure for the measurements of the redox capacity of rocks and minerals is presented. Both solid and pulverized samples are used. In a preliminary test described in this paper, an oxygen loss of an aqueous solution in contact with pulverized granodiorite was measured directly on-line, with an oxygen sensor.

The increase of Fetot in the solution responded relatively well to the oxygen consumption. The maximum rate varied from 3.0 × 10−4 to 9.0 × 10−11 mol l−1 s−1 correspondingly. Oxygen loss of 0.04 mmol (O2) and iron increase of 0.1 mmol were recorded in the solution. Fe(II) reduction in the solid phase was also examined. Fe(II) was inferred to have partially dissolved during the experiment. When the system was equilibrated at the ambient conditions, the vessel was pressurized upto 100 bar with oxygen gas. Three weeks later, the additional decrease of Fe(II) in the solid phase was minimal, only 0.07 % Fe(II) was dissolved or oxidized on the rock surfaces. At this point, the Fetot in the solution, had decreased down to the background level. According to the total oxygen loss at the ambient coditions, the maximum redox capacity of the examined granodiorite (BET 1.0 m2/g) is 0.002 mmol/m2.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 212: Symposium P – Scientific Basis for Nuclear Waste Management XIV , 1990 , 839
Copyright
Copyright © Materials Research Society 1991

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References

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