A kinetic method for the microdetermination of perbromate

Lazarou, Lazaros; Siskos, P. A.; Koupparis, Michael A.; Hadjiioannou, T.P.; Appelman, Evan H.

doi:10.1016/s0003-2670(01)84554-2

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…The pH of the solution was then adjusted to ca. 7 and the unreacted arsenite was titrated with I3-Bromate was determined by acidifying the solution, adding excess iodide and a trace of ammonium molybdate, and titrating the Hf ormed with thiosulfate. This method was also used to monitor the reaction of chlorite with perbromate.…”

Section: Methodsmentioning

confidence: 99%

Some reactions of the perbromate ion in aqueous solution

Appelman¹,

Klaening²,

Thompson³

1979

J. Am. Chem. Soc.

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The reaction of the perbromate ion with a number of two-equivalent reductants have been studied in aqueous solution at an ionic strength of approximately one. Reaction rates increase in the order N3-< CIO2-~SeOs2-~NO2-< P(III) « S(IV) < As(III) < Sb(III). The perbromate-sulfur (IV) reaction obeys the rate law -d[Br04~]/dí = &s[BrC>4~] in solutions more basic than pH 4.5. At 25 °C, ks -5.8 X 10-3 L/mol-s. The perbromate-arsenic(III) reaction obeys the rate law -d[Br04-]/dí = [(/k,[H+] + k2Ki + ^3Aii/[H+])/(ArI + [H+])][Br04~][As(III)]. At 39.7 °C, k\ = 5.6 X 10'4 L/ mol-s, k2 = 1.96 X 10-2 L/mol-s: k2 = 1.16 X 10-13 s_1, and K\= 1.6 X 10-9 M. This rate law can be interpreted in terms of increasing reactivity of the species H3ASO3, H2ASO3-, and HASO32-toward perbromate. In strong base, the perbromate-antimony(III) reaction'obeys the.rate law -d[Br04"]/dí = £sb[BrC)4~][Sb(III)], where'ksb = 0.47 L/mol-s at 25 °C.'Activation parameters were determined for the sulfur(IV), arsenic(III), and antimony(III) reactions, and the dependences of the S(IV) and As(III) reactions on total salt concentration were elucidated. The results of isotopic tracer studies show that in its reactions with S(IV) and As(III) the perbromate ion transfers one of its oxygen atoms to the reductant. Oxygen exchange between 0.14 M KBr04 and water proceeded to less than 7% of completion in the course of 19 days at 94 °C, in solutions ranging from Q.06 M acid to 0.02 M base. The implications of all of these results are discussed.X coordination came from and l3C NMR data and from the effects of coordinating solvents. The enolate intermediates were isolated as their enol silyl ethers, or they were treated with methyl iodide, allyl bromide, methyl bromoacetate, or molecular bromine. The course of enolate reaction with these electrophiles was distinctly and reproducibly different in the absence or in the presence of copper(l). Even small amounts of copper(l) decreased the amount of polyalkylation and increased the amount of m-2-alkyl-3-phenylcyclopentanone produced, even though this epimer is less stable thermodynamically then the corresponding tra/«-2-alkyl-3-phenylcyclopentanone. An explanation for this dramatic and catalytic effect of copper(l) is offered. Reaction of the more substituted enolate of 2-methyl-3-phenylcyclopentanone with methyl bromoacetate gave 2,2,3-trisubstituted cyclopentanone 25 stereospecifically; cyclopentanones like 25 should be useful precursors to AB-aromatic 19-norsteroids.

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Section: Methodsmentioning

confidence: 99%

Some reactions of the perbromate ion in aqueous solution

Appelman¹,

Klaening²,

Thompson³

1979

J. Am. Chem. Soc.

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“…This paper is aimed at demonstrating bromate and perbromate formation on BDD in bromide electrolysis. Electrochemical perbromate formation on BDD anodes has been reported for the first time by the authors [30][31][32], while analysis papers on perbromate formation have been published by Lazarou and co-workers [33,34]. The new possibilities for perbromate analysis have been reported recently by other authors as well [35].…”

Section: Introductionmentioning

confidence: 96%

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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“…BrCV + Fe2+ (FeOH+) (fast) (6) Fe02+ 4-Fe2+ 4-2H+ 2Fe3+ 4-H20 (termination) (7) The formation of triiodide is negligible because the iodide concentration is always very small ([T] < 4 M). Also, the rate of reaction 1 is very small (k' = 1.6 X 10"3 M"1 s"1 for µ = 0.10) (11) compared to the rate of reaction 3.…”

Section: Resultsmentioning

confidence: 99%

“…The perbromate-iodide reaction is well known and it was used for the detection (4,5) and the iodometric (6) and kinetic determination of perbromate (7). Iodide reduces perbromate to brómate in alkaline or neutral solutions according to the reaction Br04" + 3 + 2H+ -BrC>3~+ I3" + H2O (1) and to bromide in acidic solutions (6).…”

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confidence: 99%