Potentiometric Determination of Bromate Using an Fe(III)-Fe(II) Potential Buffer by Circulatory Flow-Injection Analysis

Ohura, Hiroki; Imato, Toshihiko; Kameda, Kiminori; Yamasaki, Satoshi

doi:10.2116/analsci.20.513

Cited by 11 publications

(5 citation statements)

References 15 publications

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“…By definition, the value of x is equal to 0 for the solution obtained by dissolution of pure bromine, Br 2 (even though this species may be subjected to various transformations, e.g., to hydrolysis) in water while, according to Equation (9), it varies from −1 for pure Br − solution to +5 for pure BrO 3 − one. If the system in its initial state (prior to electrolysis) is prepared by dissolution of N ini moles of a substance where each species (molecule or ion) contains n ini Br atoms and where the total oxidation number is equal to x ini , then N tot = n ini N ini , and Q ini = F x ini N ini .…”

Section: Definitions and Balance Relationsmentioning

confidence: 99%

“…For reactions involving bromate interactions with reducing solutions in the course of redox titrations, a similar analysis was also performed in Refs. [9,10]. However, due to various reasons (low concentrations of bromine compounds compared to the overall salt content; addition of buffer or correcting additives to the solution), the performed analysis was limited to calculating the equilibrium composition and the redox potential of the solution at a particular pH value, or for the range of pH values determined by the acid-base equilibria between Br-containing species, taking into account the effect of a titrating agent.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane–Electrode Assembly with a Proton-Exchange Membrane

Konev,

Zader,

Vorotyntsev

2023

IJMS

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The passage of cathodic current through the acidized aqueous bromate solution (catholyte) leads to a negative shift of the average oxidation degree of Br atoms. It means a distribution of Br-containing species in various oxidation states between −1 and +5, which are mutually transformed via numerous protonation/deprotonation, chemical, and redox/electrochemical steps. This process is also accompanied by the change in the proton (H+) concentration, both due to the participation of H+ ions in these steps and due to the H+ flux through the cation-exchange membrane separating the cathodic and anodic compartments. Variations of the composition of the catholyte concentrations of all these components havehas been analyzed for various initial concentrations of sulfuric acid, cA0 (0.015–0.3 M), and two values of the total concentrations of Br atoms inside the system, ctot (0.1 or 1.0 M of Br atoms), as functions of the average Br-atom oxidation degree, x, under the condition of the thermodynamic equilibrium of the above transformations. It is shown that during the exhaustion of the redox capacity of the catholyte (x pass from 5 to −1), the pH value passes through a maximum. Its height and the corresponding average oxidation state of bromine atoms depend on the initial bromate/acid ratio. The constructed algorithm can be used to select the initial acid content in the bromate catholyte, which is optimal from the point of view of preventing the formation of liquid bromine at the maximum content of electroactive compounds.

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Section: Definitions and Balance Relationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane–Electrode Assembly with a Proton-Exchange Membrane

Konev,

Zader,

Vorotyntsev

2023

IJMS

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“…It is noteworthy that during these experiments the molar mass sum of BrO 3 − and Br − also slightly decreased from 0.50 µM to 0.48 µM and 0.46 µM for 0.003 mM and 0.033 mM Fe 2+ dosages, respectively, indicating the formation of Br intermediate species. The most frequently reported intermediate species is hypobromous acid (HOBr/BrO − ) [31,64]. Furthermore, the study of Shen et al [60] showed that the sum of BrO It has been reported that the lower the pH of FeOOH formation, the higher the positive surface charge density [65].…”

Section: Bro 3 − Reduction Under Concentrations Similar To Marmentioning

confidence: 99%

Bromate Reduction by Iron(II) during Managed Aquifer Recharge: A Laboratory-Scale Study

Wang

Salgado

Hoek

et al. 2018

Water

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The removal of bromate (BrO 3 − ) as a byproduct of ozonation in subsequent managed aquifer recharge (MAR) systems has so far gained little attention. This preliminary study with anoxic batch experiments was executed to explore the feasibility of chemical BrO 3 − reduction in Fe-reducing zones of MAR systems and to estimate potential inhibition by NO 3 − . Results show that the reaction rate was affected by initial Fe 2+ /BrO 3 − ratios and by pH. The pH dropped significantly due to the hydrolysis of Fe 3+ to hydrous ferric oxide (HFO) flocs. These HFO flocs were found to adsorb Fe 2+ , especially at high Fe 2+ /BrO 3 − ratios, whereas at low Fe 2+ /BrO 3 − ratios, the mass sum loss of BrO 3 − and Br − indicated intermediate species formation. Under MAR conditions with relatively low BrO 3 − and Fe 2+ concentrations, BrO 3 − can be reduced by naturally occurring Fe 2+ , as the extensive retention time in MAR systems will compensate for the slow reaction kinetics of low BrO 3 − and Fe 2+ concentrations. Under specific flow conditions, Fe 2+ and NO 3 − may co-occur during MAR, but NO 3 − hardly competes with BrO 3 − , since Fe 2+ prefers BrO 3 − over NO 3 − . However, it was found that when NO 3 − concentration exceeds BrO 3 − concentration by multiple orders of magnitude, NO 3 − may slightly inhibit BrO 3 − reduction by Fe 2+ . applied to bromide-containing water [12-14]. It has been reported that the BrO 3 − concentration in drinking water after ozone-based AOPs typically ranges from 0 to 127 µg/L (1 µM) [15]. BrO 3 − is classified as Group 2B, or possible human carcinogen, by the International Agency for Research on Cancer based on its major toxic effects [16-18]. The standard of BrO 3 − in drinking water regulated by the World Health Organization, the US Environmental Protection Agency, and the European Union is 10 µg/L [19-21], demanding water companies to control the BrO 3 − concentration in drinking water.

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“…Furthermore, repetitive determinations of a large number of trace samples of bromate were proposed by the circulating (closed-loop) FIA (CFIA), which is more suited to the concept of the Zero Emission Research Initiative [30]. The equilibrium potential obtained via the large transient potential change was nearly equal to the initial potential because the concentration of Fe(III)-Fe(II) in the potential buffer was sufficiently higher than that of bromate in the sample.…”

Section: Analyses Utilizing a Large Transient Potential Change Caumentioning

confidence: 99%

Rapid and Automated Analytical Methods for Redox Species Based on Potentiometric Flow Injection Analysis Using Potential Buffers

Ohura

Imato

2011

Journal of Automated Methods and Management in Chemistry

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Two analytical methods, which prove the utility of a potentiometric flow injection technique for determining various redox species, based on the use of some redox potential buffers, are reviewed. The first is a potentiometric flow injection method in which a redox couple such as Fe(III)-Fe(II), Fe(CN)6 3−-Fe(CN)(CN)6 4−, and bromide-bromine and a redox electrode or a combined platinum-bromide ion selective electrode are used. The analytical principle and advantages of the method are discussed, and several examples of its application are reported. Another example is a highly sensitive potentiometric flow injection method, in which a large transient potential change due to bromine or chlorine as an intermediate, generated during the reaction of the oxidative species with an Fe(III)-Fe(II) potential buffer containing bromide or chloride, is utilized. The analytical principle and details of the proposed method are described, and examples of several applications are described. The determination of trace amounts of hydrazine, based on the detection of a transient change in potential caused by the reaction with a Ce(IV)-Ce(III) potential buffer, is also described.

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Potentiometric Determination of Bromate Using an Fe(III)-Fe(II) Potential Buffer by Circulatory Flow-Injection Analysis

Cited by 11 publications

References 15 publications

Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane–Electrode Assembly with a Proton-Exchange Membrane

Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane–Electrode Assembly with a Proton-Exchange Membrane

Bromate Reduction by Iron(II) during Managed Aquifer Recharge: A Laboratory-Scale Study

Rapid and Automated Analytical Methods for Redox Species Based on Potentiometric Flow Injection Analysis Using Potential Buffers

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