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Proceedings Paper

Fiber-optic-based pH measurement in a geothermal brine
Author(s): Stuart Farquharson; Paul D. Swaim; C. P. Christenson; Mary McCloud; Henry Freiser
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Paper Abstract

The measurement of pH in industrial chemical process is well established. Since pH can affect reaction rates, system corrosion, and/or water quality, a number of on-line electrodes have been commercialized. However, these devices necessarily contain a porous membrane (usually glass) to allow the flow of hydrogen ions which provides the electrical potential for measurement. In a recent application to a geothermal brine solution, we were unable to eliminate electrode fouling, even with considerable sample conditioning. As an alternative, we designed and constructed an in-line pH instrument based on the spectroscopic absorption of acid-base indicator dyes. The instrument introduced bromocresol green into the stream via a static mixer and measured the ratio of the characteristic acidic and basic absorption bands using an in-line fiber optic cell. Details of the design and its application are presented.

Paper Details

Date Published: 1 March 1992
PDF: 8 pages
Proc. SPIE 1587, Chemical, Biochemical, and Environmental Fiber Sensors III, (1 March 1992); doi: 10.1117/12.56558
Show Author Affiliations
Stuart Farquharson, Dow Chemical USA (United States)
Paul D. Swaim, Dow Chemical USA (United States)
C. P. Christenson, Dow Chemical USA (United States)
Mary McCloud, Redhill Geothermal Inc. (United States)
Henry Freiser, Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 1587:
Chemical, Biochemical, and Environmental Fiber Sensors III

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