Stabilized Ceramic Membrane Electrodes for the Measurement of pH at Elevated Temperatures

Tsuruta, Takao; Macdonald, Digby D.

doi:10.1149/1.2124090

Cited by 51 publications

(19 citation statements)

References 17 publications

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“…Tsuruta and MacDonald reported a smaller pH at high temperature above 250°C for the aqueous H2SO4 solution of 0.005M, as compared with the calculation assuming complete dissociation in the first dissociation reaction (20). The calculated pH at 275°C of 3.56 considering the temperature dependence of K~ and K2 shows a good agreement with their measured value of 3.6.…”

Section: Fig 12 Correlations Between Conductivities At 25 ° and 300°csupporting

confidence: 68%

In‐Line Monitor for Electrical Conductivity of High‐Temperature, Aqueous Environments

Asakura

Nagase

Sakagami

et al. 1989

J. Electrochem. Soc.

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An in-line monitor to determine electrical conductivity of aqueous solutions at elevated temperatures up to 300~ was developed. By analyzing the frequency dependence of the impedance between three plating electrodes, the water resistivity was estimated separately from the impedance due to the surface reactions, which was the error source in electrical conductivity measurements at high temperature. By using the monitor, the effects of aqueous impurities, H2SO4, NaOH, and Na2SO4 on the electrical conductivity were elucidated up to 300~ Based on the measured conductivities, the first dissociation constant of H2SO4 in high-temperature water was determined.Changes in water qualities, such as pH, conductivity, oxygen concentration, and impurity compositions can affect the corrosion behavior of structural materials. In the primary system of boiling water reactors (BWRs), many kinds of in-line monitors for water qualities are installed, but almost all of them are designed to be used at room temperature. Thus for water quality monitoring, the sampled water must be cooled down, which causes possible changes in its quality. Conductivity measurements constitute an important method for monitoring continuously the amount of ionic impurities. However, in these measurements, it must be considered that the degree of ionization varies appreciably with temperature, and further, that this dependence on temperature also depends on the chemical form of impurities.These facts suggest that direct measurement of the electrical conductivity of high-temperature water is useful both for precise determination of water qualities and precise estimation of the effects of impurities on corrosion behavior (1-3).Alternating-current conductivity bridges have been applied to measurement of the liquid resistance between two platinum electrodes at elevated temperature. However, reliability of the measured conductivity was not generally achieved owing to surface effects, geometrical deformation of the sensor at elevated temperature, and changes in the water quality in the narrow channel between the platinum electrodes during the measurement. These factors cause errors of up to 50% at temperature above 150~ (4, 5).In this paper, the authors propose an in-line monitor to determine electrical conductivity of water at temperatures up to 300~ The main feature of the monitor is that the resistivity of the water between the platinum electrodes can be estimated separately from the impedance caused by surface reactions on the platinum electrodes. This surface impedance becomes a source of error in electrical conductivity measurements at elevated temperature. By using the monitor, effects of aqueous impurities on electrical conductivity at elevated temperatures are elucidated.

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Section: Fig 12 Correlations Between Conductivities At 25 ° and 300°csupporting

confidence: 68%

In‐Line Monitor for Electrical Conductivity of High‐Temperature, Aqueous Environments

Asakura

Nagase

Sakagami

et al. 1989

J. Electrochem. Soc.

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“…The operation mechanism and thermodynamics of a ZrO 2 (Y 2 O 3 ) sensor with a Hg/HgO internal half-element were first studied by Tsuruta and Macdonald (1982) and Macdonald et al (1988) and afterwards thoroughly reviewed by Lvov et al (2003). The potential-forming equilibrium may be described in terms of oxygen vacancies on the solution side and on the internal contact side, respectively:…”

Section: Ceramic Electrode Operationmentioning

confidence: 99%

Determination of the HCl dissociation constant at a temperature of 350°C and 200 bars of pressure by the potentiometric method using a ceramic electrode

Reukov

Зотов

2006

Geol. Ore Deposits

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A technique has been developed for pH measurement in flow-through cells at temperatures from 175 to 350 ° C and pressures up to 350 bars in a nonisothermal cell consisting of a ZrO 2 (Y 2 O 3 ) ceramic electrode and a Ag/AgCl (2 M KCl, 25 ° C) flow-through reference electrode. This technique has been applied to determination of the HCl dissociation constant at 350 ° C and 200 bars; previously, the HCl dissociation has not been studied sufficiently reliably under these conditions. The obtained value p K dis = 2.16 ± 0.03 was used to estimate the acidity of fluids from their chemical composition at the vent of high-temperature submarine hydrothermal solutions.

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“…The results were compared to those of C SPEs in order to determine whether the Ce-based oxides were of interest. Measurements for increasing and decreasing pH values were taken for 5 minutes, at a rate of one reading every Zirconia membranes have been reported to be ideally suited to pH measurements at temperatures higher than 150 °C [24,25]. Sm-substituted ceria ceramic membrane-type pH sensors have been shown to have a Nernstian slope in buffer solutions at 75 °C [31,32].…”

Section: Feasibility Studymentioning

confidence: 99%

“…Niedrach (1980 a,b) was the first to report on the application of zirconium oxide (zirconia, ZrO 2 ) membrane-type potentiometric sensors for pH measurements [22,23]. However, this membrane electrode exhibited only a near-Nernstian-pH response at high temperatures [24,25] and, because of their high impedance [26], pH sensors with zirconia membranes were reported to exhibit sluggish and sub-theoretical responses at temperatures below 150 °C [27].…”

Section: Introductionmentioning

confidence: 99%

Novel CeO2-based screen-printed potentiometric electrodes for pH monitoring

Betelu

Polychronopoulou

Rebholz

et al. 2011

Talanta

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Nuclear waste repositories are being installed in deep excavated rock formations in some places in Europe to isolate and store radioactive waste. In France, the Callovo-Oxfordian formation (COx) is a possible candidate for nuclear waste storage. This work investigates the applicability of CeO 2 -based oxides (CeO 2 , Ce 0.8 Sm 0.2 O 2 and Ce 0.8 Zr 0.2 O 2 ) for monitoring the pH of the COx pore water. The study is limited to the pH range between 5.5 and 13.2, which includes the pH values that have been encountered or are anticipated in the COx formation during its evolution as radioactive waste repository due mainly to alkalinisation, an increase in salinity, a decrease in redox potential. Screen-printing was done to assemble electrodes and rapidly generate data sets. The electrochemical behavior of CeO 2 -based screen-printed electrodes (CeO 2 -based SPEs) was determined by cyclic voltammetry and electrochemical impedance spectroscopy. The use of the electrodes for pH sensing was then evaluated by potentiometric measurements. The feasibility of measuring pH with CeO 2 -based SPEs was first tested in NH 4 Cl/NH 3 buffer solutions, leading to electrode calibration over the widest range of pH, from around neutral to basic pH. Experiments were then conducted in NaHCO 3 /Na 2 CO 3 buffer samples similar to conditions prevailing in the COx formation.Ce 0.8 Zr 0.2 O 2 SPEs exhibit a near-Nernstian behavior (sensitivity -(51±2)mV/pH) in the pH range 5.5-13.2 at 25 °C. Electrode response was slightly affected by the direction of the pH change. Electrode reliability was clearly demonstrated for pH monitoring. Probes based on the same components, but more durably designed, could be considered for pH measurements in radioactive waste repositories.

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Stabilized Ceramic Membrane Electrodes for the Measurement of pH at Elevated Temperatures

Cited by 51 publications

References 17 publications

In‐Line Monitor for Electrical Conductivity of High‐Temperature, Aqueous Environments

In‐Line Monitor for Electrical Conductivity of High‐Temperature, Aqueous Environments

Determination of the HCl dissociation constant at a temperature of 350°C and 200 bars of pressure by the potentiometric method using a ceramic electrode

Novel CeO2-based screen-printed potentiometric electrodes for pH monitoring

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