On the electrolysis of aqueous bromide solutions to bromate

Cettou, P.; Robertson, P.M.; Ibl, N.

doi:10.1016/0013-4686(84)87131-5

Cited by 43 publications

(36 citation statements)

References 16 publications

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“…One conclusion is the role of chemical reactions, for instance in the formation of bromate. Already Cettou et al [57] and Pavlovic et al [58] explained the bromate formation from bromide on RuO 2 anodes by a predominating chemical mechanism (Eqs. 27 and 28).…”

Section: Perbromate Formationmentioning

confidence: 98%

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The occurrence of bromate and perbromate on BDD anodes during electrolysis of aqueous systems containing bromide: first systematic experimental studies

2011

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Bromide electrolysis was carried out on laboratory-scale cells in the range of 1-1,005 mg [Br -] dm -3 using boron-doped diamond (BDD) anodes. These studies were part of fundamental research activities on drinking water electrolysis for disinfection. Synthetic water systems were mostly used in the experiments, which varied the temperature between 5 and 30°C, the current density between 50 and 700 A m -2 , and the rotation rate of the rotating anode between 100 and 500 rpm (laminar regime). Hypobromite and bromate were found as by-products, as expected. Bromite was not detected. Higher bromate levels were formed at higher current density, but no clear relationship was observed between bromate concentration and the rotation rate or temperatures between 5 and 30°C. Bromate yields higher than 90% were found at higher charge passed. Perbromate was found as a new potential synthesis or disinfection by-product (DBP), but no perbromate was detected at the lowest bromide concentrations and under drinking water conditions. The perbromate yield was about 1%, and somewhat lower when bromate was used as a starting material instead of bromide. At a temperature of 5°C more perbromate was detected compared with experiments at 20°. Approximately 20 times more perchlorate was formed compared with perbromate formation in the presence of chloride ions of equimolar concentration. State of mechanistic considerations is presented and a mechanism for perbromate formation is proposed. The reaction from bromate to perbromate was found to be limited that is in contrast to the earlier studied chlorate-to-perchlorate conversion. In the measured concentration range, reduction processes at the mixed oxide cathode showed a much higher impact on the resulting concentration for perbromate than for bromate. Keywords Electrochemical disinfection Á Drinking water Á Bromide electrolysis Á Bromate Á Perbromate Á BDD Á Disinfection by-products List of symbols BDD Boron Doped Diamond c Concentration (mg dm -3 ) D Diffusion coefficient (m 2 s -1 ) DPD Diphenylendiamine E Electrode potential (V (SHE)) F FARADAY constant (As mol -1 ) I Current (A) IC Ion chromatography i lim Limiting current density (A m -2 ) k Reaction rate constant (M -1 s -1 , M -2 s -2 ) n Number of electrons transferred M Molar mass (mg mol -1 ) r Electrode radius (m) Re = xÁr 2 /m Reynolds number RDE Rotating disk electrode RNO p-Nitrosodimethylaniline rpm Revolutions per minute Sc = m/D Schmidt number Sh = bÁr/D Sherwood number SHE Standard Hydrogen Electrode

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Section: Perbromate Formationmentioning

confidence: 98%

“…Cettou and coworkers [57] have discussed bromate formation by addition of the O • radical to the hypobromite ion (Eq. 34)-as a side reaction with main chemical reactions (Eqs.…”

Section: The Role Of O • Radical As a Probable Reactantmentioning

confidence: 99%

The occurrence of bromate and perbromate on BDD anodes during electrolysis of aqueous systems containing bromide: first systematic experimental studies

2011

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“…The electrochemistry of Brunder aqueous conditions is summarized in Eqn 1-4. [17] Two noteworthy aspects are the small equilibrium constant between Br2 and Br3in the presence of Br -(Keq = 17) [22] and the more rapid ET kinetics of Br2 with the electrode surface. [23] The formation constant (Keq) for Br3is significantly lower than that of triiodide in water (I3 -, Keq = 698) [24] or for the same reaction to form tribromide in nonaqueous solvents (Keq > 10 6 ).…”

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confidence: 99%

Light‐Driven Water Splitting Mediated by Photogenerated Bromine

Sheridan

Wang

et al. 2018

Angew Chem Int Ed

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Light-driven water splitting was achieved using a dye-sensitized mesoporous oxide film and the oxidation of bromide (Br ) to bromine (Br ) or tribromide (Br ). The chemical oxidant (Br or Br ) is formed during illumination at the photoanode and used as a sacrificial oxidant to drive a water oxidation catalyst (WOC), here demonstrated using [Ru(bda)(pic) ], (1; pic=picoline, bda=2,2'-bipyridine-6,6'-dicarboxylate). The photochemical oxidation of bromide produces a chemical oxidant with a potential of 1.09 V vs. NHE for the Br /Br couple or 1.05 V vs. NHE for the Br /Br couple, which is sufficient to drive water oxidation at 1 (Ru ≈1.0 V vs. NHE at pH 5.6). At pH 5.6, using a 0.2 m acetate buffer containing 40 mm LiBr and the [Ru(4,4'-PO H -bpy)(bpy) ] (RuP , bpy=2,2'-bipyridine) chromophore dye on a SnO /TiO core-shell electrode resulted in a photocurrent density of around 1.2 mA cm under approximately 1 Sun illumination and a Faradaic efficiency upon addition of 1 of 77 % for oxygen evolution.

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“…For example, in the catholyte of halogen-based flow batteries, diatomic halogen molecules and halide ions react to form polyhalide complexes with often higher solubility than the halogen molecule. 1,4 As battery maximum energy density is proportional to the solubility of the reactant, this complexation reaction is often a key feature underpinning the promise of halogen batteries. 5 Numerous flow batteries employ halogen-based catholytes, including hydrogenbromine, 3 zinc-bromine, 6 quinone-bromine, 8,13 hydrogen-chlorine, 9 zinc-iodine, 10 and several others.…”

mentioning

confidence: 99%

“…In bromine-based batteries, the tribromide complex created by the reaction Br 2(aq) + Br − (aq) ⇔ Br − 3(aq) is often mentioned as a significant oxidizing agent due to the high complexation equilibrium constant of K eq = 17, [14][15][16] while higher order polyhalides are typically neglected due to their lower concentrations in the catholyte. 4,17,18 In addition to polyhalide complexes, other complexes may form in battery electrolytes, such as the zinc-bromide complexes in the anolyte and catholyte of zinc-bromine batteries (e.g. ZnBr 2 , ZnBr 3 − , ZnBr 4 −19 ).…”

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confidence: 99%

Theory of Flow Batteries with Fast Homogeneous Chemical Reactions

Ronen

Atlas

Suss

2018

J. Electrochem. Soc.

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Redox flow batteries are widely investigated toward cost-effective storage of energy generated via intermittent renewable sources. Many redox chemistries have been proposed for flow batteries, possessing various attractive features such as low-cost reactants, fast electrochemical reaction kinetics without precious metal catalysts, negligible thermal runaway risk, and low toxicity. While all flow batteries rely on heterogeneous electrochemical reactions occurring at electrode surfaces, in a subset of chemistries homogeneous chemical reactions occur in the electrolyte. A prominent example are batteries employing halogen-based catholytes, where halogen molecules complex with halide ions in the catholyte, forming redox-active polyhalide ions. However, state-of-the-art models capturing flow battery performance for halogen systems typically neglect the presence of such homogeneous reactions and polyhalide ions. The latter assumption allows for simpler models, but at the cost of accurately predicting battery chemical state and performance. We here present a generalized flow battery theory extended to include fast homogeneous reactions, which employs a technique known as the method of families to simplify the governing equations. We then apply and solve the model for the specific case of a membraneless hydrogen-bromine flow battery, illustrating the predicted effect of the homogeneous complexation reaction in the catholyte on flow battery performance.

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On the electrolysis of aqueous bromide solutions to bromate

Cited by 43 publications

References 16 publications

The occurrence of bromate and perbromate on BDD anodes during electrolysis of aqueous systems containing bromide: first systematic experimental studies

The occurrence of bromate and perbromate on BDD anodes during electrolysis of aqueous systems containing bromide: first systematic experimental studies

Light‐Driven Water Splitting Mediated by Photogenerated Bromine

Theory of Flow Batteries with Fast Homogeneous Chemical Reactions

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