The Decomposition of Hypochlorite-Hypobromite Mixtures in the pH Range 7 10

Lewin, Menachem; Avrahami, M.

doi:10.1021/ja01622a014

Cited by 39 publications

(32 citation statements)

References 11 publications

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“…BrO 3 À þ 3H þ þ 2Cl À ð18Þ Chlorate may be a product of chemical interactions between HOCl and HOBr [53]-in dependence on the concentration peculiarities:…”

Section: Perbromate Formationmentioning

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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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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“…BrO 3 À þ 3H þ þ 2Cl À ð18Þ Chlorate may be a product of chemical interactions between HOCl and HOBr [53]-in dependence on the concentration peculiarities:…”

Section: Perbromate Formationmentioning

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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“…NHBr2 + NBr2Cl + 2H20 ----+ N2 + 2HOBr + 2HBr + HCl (40) k7PX2 NHBrCl + NBrzCl + 2H20 Nz + 2H0Br + HBr + 2HC1 k70 (41) 2Nlir2Cl…”

Section: 56 D Arpenter Et Amentioning

confidence: 99%

Kinetic model for predicting the concentrations of active halogens species in chlorinated saline cooling waters. Final report

Haag¹,

Lietzke²

1981

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“…The rate constant for this disappearance is shown to increase slightly with increasing HOBr-OBror bromide ion concentration and to decrease strongly with in-creasingpH (7). It is observed to be independent of the chloride ion concentration up to 0.5M (6). No photolytic effects were investigated.…”

mentioning

confidence: 90%

“…While pure TCDD is unstable toward ultraviolet light when dissolved in organic solvents such as methanol or benzene (6), it otherwise has the reputation of being very stable and persistent (7). However, opportunities for it to occur environmentally in pure form are negligible; its more probable behavior as a trace contaminant dissolved in pesticide mixtures would seem to have much more significance but, remarkably, has not been reported.…”

mentioning

confidence: 99%