HOI versus HOIO Selectivity of a Molten-type AgI Electrode

Holló, Gábor; Kály‐Kullai, Kristóf; Lawson, Thuy; Noszticzius, Zoltán; Wittmann, Mária; Muntean, Norbert; Furrow, Stanley D.; Schmitz, Guy

doi:10.1021/jp504052w

Cited by 8 publications

(6 citation statements)

References 39 publications

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“…For the preparation of I(+3) solution in concentrated sulfuric acid, I(+3) solution was also prepared with comproportion as in the case of I(+1) but by applying a larger amount of iodate in the reaction between KIO 3 dissolved in concentrated H 2 SO 4 and I 2 dissolved in DCM. The exact recipe can be found in ref as I(+3)–C.…”

Section: Methodsmentioning

confidence: 99%

“…(See Figure 5a in ref 6. ) In another previous publication, 7 we also tested the effect of other oxyiodine species, such as iodous and iodic acids, on the electrode potential. In theory, these acids could contribute to the corrosion of AgI, and the extra silver ions produced this way might affect the electrode potential.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, we have started systematic research with the aim to describe how the various intermediates of the BR reaction affect the potential of these two most frequently used indicator electrodes. In two previous publications, , we dealt with the potential response of the AgI electrode, and now we focus on the platinum electrode. As we should like to compare the behavior of the two electrodes, to show both the similarities and also the dissimilarities in their potential response, first we summarize briefly our previous results with the AgI electrode, and then we give an overview of our present experiments with the Pt electrode.…”

Section: Introductionmentioning

confidence: 99%

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Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

et al. 2017

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Pt is a common redox electrode used to follow oscillations qualitatively in the Briggs-Rauscher (BR) and the Bray-Liebhafsky (BL) reactions from the time of their discovery. Although the potential oscillations of the electrode reflect the temporal pattern of the reaction properly, there is no general agreement as to how that potential is determined by the components of the reaction mixture. In this article, first we investigate how iodine species in different oxidation states affect the potential of a Pt electrode. It was found that I(+3) and I(+5) species do not affect the potential; only I, I, and HOI may have an influence. Although the latter three species are always present simultaneously as participants of the rapid iodine hydrolysis equilibrium, it was found that below and above the so-called hydrolysis limit potential (HLP, where the iodide and HOI concentrations are equal) the actual potential determining redox couple is different. Below the HLP, it is the traditional I/I redox couple, but above the HLP, it is the HOI/I redox pair that determines the potential of a Pt electrode. That change in the potential control mechanism was proven experimentally by exchange current measurements. In addition, from the potential response of the Pt electrode below and above the HLP, it was possible to calculate the equilibrium constant of the iodine hydrolysis as K° = (4.97 ± 0.20) × 10 M, in rather good agreement with earlier measurements. We also studied the perturbing effect of HO on the previously mentioned potentials. The concentration of HO was 0.66 M, as in the BR reaction studied here. It was found that below the HLP, the perturbing effect of HO was minimal but above the HLP, HO shifted the mixed potential considerably down toward the HLP. In our experiments with the BR reaction, the potential oscillations of the Pt electrode crossed the HLP, indicating that from time to time the HOI concentration exceeds that of the iodide. We can conclude that although the perturbing effect of HO prevents the calculation of concentrations from Pt potentials above the HLP, [I]/[I] ratios can be calculated as a good approximation from Pt potentials below the HLP.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

et al. 2017

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“…The bromine is extracted by air blowing in low concentration brine and the acidification pH value of the brine is controlled to about 3.5 [43]. When the pH value is higher than 4, the hydrolysis of bromine is intensified which affects the extraction rate.…”

Section: Optimum Parameters 41 the Optimum Range Of Ph During Brine Oxidation Processmentioning

confidence: 99%

Monitor application of multi-electrochemical sensor in extracting bromine from seawater

Wang

Zhao

et al. 2019

R. Soc. open sci.

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In this paper, a set of online measurement devices of multi-electrochemical sensor was investigated. Combined with industrial distributed control system, it was first applied in extracting bromine from seawater to realize the real-time adjustment of production process parameters. In the process of extracting bromine from seawater, the pH value of acidified raw brine, the addition amount of Cl2 in the oxidation stage and the addition amount of SO2 in the absorption stage are key parameters to control the whole production process. The multi-electrochemical sensor realized a rapid and high-throughput detection of the above parameters by integrating an all-solid-stage bromide ion selective electrode (Br-ISE), Eh electrode and pH electrode. The Br-ISE and the pH electrode were self-developed electrodes and the Pt electrode was Eh electrode. The pH electrode was used to control the addition amount of H2SO4 during the acidification of the brine. The Eh electrode was used to control the addition amount of Cl2 during the oxidation stage and the addition amount of SO2 during the absorption stage. The Br-ISE was used to monitor the Br− concentration change in the raw brine. Results showed the optimum range of Eh in the oxidation stage and absorption stage of brine were 950–1000 mV and 580–610 mV, respectively. The application of multi-electrochemical sensor in industrial bromine production can realize real-time control of material addition and save the cost of production.

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“…Mentioned reactions (R) and (O) are complex and their mechanisms involve several intermediate species (Bray, 1921;Liebhafsky, 1931;Woodson and Liebhafsky, 1969;Furrow, 1985Furrow, , 1987Stanisavljev et al, 2013;Holló et al, 2014). In general, alternating increases and decreases of the intermediate species concentrations in time appear as a consequence of alternating dominations of reactions (R) and (O).…”

Section: Introductionmentioning

confidence: 99%

Intermittent Chaos in the CSTR Bray–Liebhafsky Oscillator-Specific Flow Rate Dependence

et al. 2020

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Dynamic states with intermittent oscillations consist of a chaotic mixture of large amplitude relaxation oscillations grouped in bursts, and between them, small-amplitude sinusoidal oscillations, or even the quiescent parts, known as gaps. In this study, intermittent dynamic states were generated in Bray-Liebhafsky (BL) oscillatory reaction in an isothermal continuously-fed, well-stirred tank reactor (CSTR) controled by changes of specific flow rate. The intermittent states were found between two regular periodic states and obtained for specific flow rate values from 0.020 to 0.082 min −1. Phenomenological analysis based on the quantitative characteristics of intermittent oscillations, as well as, the largest Lyapunov exponents calculated from experimentally obtained time series, both indicated the same type of behavior. Namely, fully developed chaos arises when approaching to the vertical asymptote which is somewhere between two bifurcations. Hence, this study proposes described route to fully developed chaos in the Bray-Liebhafsky oscillatory reaction as an explanation for experimentally observed intermittent dynamics. This is in correlation with our previously obtained results where the most chaotic intermittent chaos was achieved between the periodic oscillatory dynamic state and stable steady state, generated in BL under CSTR conditions by varying temperature and inflow potassium iodate concentration. Moreover, it was shown that, besides the largest Lyapunov exponent, analysis of chaos in experimentally obtained intermittent states can be achieved by a simpler approach which involves using the quantitative characteristics of the BL reaction evolution, that is, the number and length of gaps and bursts obtained for the various values of specific flow rates.

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HOI versus HOIO Selectivity of a Molten-type AgI Electrode

Abstract: an AgI electrode can be applied to measure the HOI concentration selectively above the so-called solubility limit potential.

Cited by 8 publications

References 39 publications

Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

Monitor application of multi-electrochemical sensor in extracting bromine from seawater

Intermittent Chaos in the CSTR Bray–Liebhafsky Oscillator-Specific Flow Rate Dependence

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HOI versus HOIO Selectivity of a Molten-type AgI Electrode

Abstract: an AgI electrode can be applied to measure the HOI concentration selectively above the so-called solubility limit potential.

Cited by 8 publications

References 39 publications

Platinum as a HOI/I2 Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

Platinum as a HOI/I2 Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

Monitor application of multi-electrochemical sensor in extracting bromine from seawater

Intermittent Chaos in the CSTR Bray–Liebhafsky Oscillator-Specific Flow Rate Dependence

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Product

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Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction

Platinum as a HOI/I₂ Redox Electrode and Its Mixed Potential in the Oscillatory Briggs–Rauscher Reaction