Direct pH measurement of NaCl-bearing fluid with an in situ sensor at 400°C and 40 megapascals

Science

Volumn 272, Issue 5268, 1996, Pages 1634-1636

  Ding, Kang ^a   Seyfried Jr , William E ^a  

^a UNIVERSITY OF MINNESOTA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001687570     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.272.5268.1634     Document Type: Article

References (27)

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11. S. Hettiarachchi, K. Makela, H. Song, D. D. Macdonald, J. Electrochem. Soc. 139, L3 (1992).
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13. _, J. Solution Chem., in press.
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16. K. L. Von Damm, in (4), pp. 222-247.
17. Temperature was maintained at 400° ± 0.5°C by time-proportioning solid-state controllers, and pressure was held at 40 ± 0.1 MPa by a transducer within a Shimatzu 7A HPLC pump, which served as the fluid delivery system.
18. The reference electrode (Ag/AgCl) was installed by a method similar to that described in (10).
19. The sensing electrodes were installed next to the reactor outlet, which helped ensure correspondence between sensor response and fluid samples.
20. J. W. Johnson, E. H. Oelkers, H. C. Helgeson, Comput. Geosci. 18, 899 (1992); J. C. Tanger IV and H. C. Helgeson, Am. J. Sci. 288, 19 (1988); E. L. Shock, E. H. Oelkers, J. W. Johnson, D. A. Sverjensky, H. C. Helgeson, J. Chem. Soc. Faraday Trans. 88, 803 (1992).
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22. J. W. Johnson, E. H. Oelkers, H. C. Helgeson, Comput. Geosci. 18, 899 (1992); J. C. Tanger IV and H. C. Helgeson, Am. J. Sci. 288, 19 (1988); E. L. Shock, E. H. Oelkers, J. W. Johnson, D. A. Sverjensky, H. C. Helgeson, J. Chem. Soc. Faraday Trans. 88, 803 (1992).
23. The associatton constant of HCl° was obtained from the revised HKF equation of state (17) and associated parameters [D. A. Sverjensky, J. J. Hemley, W. M. D'Angelo, Geochim. Cosmochim. Acta 55, 988 (1991)].
24. The association constant of NaOH° was from K. Ding and W. E. Seyfried Jr., Geochim. Cosmochim. Acta 56, 3681 (1992).
25. The standard potential for Hg/HgO was calculated from G. B. Naumov, B. N. Ryzhenko, I. L. Khodakovsky, Handbook of Thermodynamic Data, I. Barnes and V. Speltz, Eds., G. J. Soleimani, Transl. (U.S. Geological Survey, Menlo Park, CA, 1974).
26. 2S (19).
27. We thank D. D. Macdonald and J. Pang for their assistance with constructing the YSZ electrode. We are also grateful to M. E. Berndt, D. A. Sverjensky, and two anonymous reviewers for critical comments. This research was supported by NSF grant OCE-9300119.