1 March 1992 Fiber-optic-based pH measurement in a geothermal brine
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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.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stuart Farquharson, Paul D. Swaim, C. P. Christenson, Mary McCloud, and Henry Freiser "Fiber-optic-based pH measurement in a geothermal brine", Proc. SPIE 1587, Chemical, Biochemical, and Environmental Fiber Sensors III, (1 March 1992); doi: 10.1117/12.56558; https://doi.org/10.1117/12.56558

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