Pulsed radiolysis and flash photolysis of iodates in aqueous solution

Barat, F.; Gilles, L.; Hickel, B.; Lesigne, B.

doi:10.1021/j100647a004

Cited by 36 publications

(16 citation statements)

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“…On the above basis the fol-S2 0i-+ 202 +H2O-•2SOr + 2H+ (15) G(-S2 0|") remains independent of NOJ ion concentration. and I(IV) which are considered to be powerful oxidants are directly formed [14][15][16][17] which in the present case oxidise S2 O3" ions directly. The sequence of the reactions appear to be as follows:…”

Section: Resultsmentioning

confidence: 68%

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Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

et al. 1977

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SummaiyT-radiolysis of neutral aqueous solutions of the redox mixtures of SjOJ-/(i) NOj, (ii) BrO; and (iii) 10; ions were studied at different concentrations and doses. The yieid viz. G(-Sj03") is 0.7 in the nitrite mixture, but enhanced values of 7.7 and 8 were observed in the bromate and iodate mixtures respectively. A point of interest is that while in the radiolysis of an aqueous Solution of pure Sj O3" ions, the products are S and Hj S, in the redox mixture SjO|" isalmost wholly converted to and SO5 A suitable mechanism is suggested to explain these results.BrOj ions and attains a plateau. On the other hand in S2 O3 7IO3 system the yield is even higher but independent of the concentration of the lOj ions. In both the latter cases it is observed that the G(-S2 O3 ") decreases with the increase of S2 O3" ions. G(Br") and G(I") are also higher in the redox mixtures than the corresponding values in pure aqueous solutions. The G values are independent of BrO J and lOi ion concentrations and attain Saturation.

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Section: Resultsmentioning

confidence: 68%

“…The low observed yield G(I") in the lOj mixtures suggests that IO2 +IO2 ^Products holds good [17], We have observed in several other redox mixtures containing lOj ions that G(n never equals to G(eäq + H) = 3.4 [20]. It may be noticed that for the sys- …”

Section: Resultsmentioning

confidence: 80%

Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

et al. 1977

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“…Furthermore, there is some uncertainty with regard to the extinction coefficients of Br02. If the values reported by Buxton and Dainton [12] were replaced by the values given by Barat et al [16], the Br02-concentrations experimentally obtained should be larger by a factor of 1.05 than assumed in Table 1; if both corrections are taken into account, there is a 20% discrepancy left only. Moreover, the Br02 extinction coefficients have been measured in neutral solution, and they may be changed when sulfuric acid solutions are used.…”

Section: Reaction (R2)mentioning

confidence: 73%

Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Försterling

Lamberz

Schreiber

1980

Zeitschrift Für Naturforschung A

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The reaction between HBr02 and bromate was studied in sulfuric acid solution. From the spectral dependence of the absorbance in the region from 400 to 600 nm it is concluded that Br02 is an intermediate of the reaction. From the maximum concentration of Br02 the equilibrium constant of the BrOa/B^O-i-equilibrium is evaluated; furthermore, a value for the ratio of the rate constants for the HBr02/Br03~-reaction and the disproportionation reaction of HBr02 is given.The autocatalytic formation of Ce 4+ is one of the essential reactions in the Belousov-Zhabotinskysystem [1,2] In preceding experiments [4,5, 6] we have been able to detect Br02 formed in this reaction. The kinetics experimentally observed was found to be in qualitative agreement with the FKN-reaction scheme. In a quantitative respect, however, the experimental results disagreed with theory; as an example, the Br02-concentrations experimentally obtained were 1/10 of the calculated values only. In order to overcome this discrepany, reaction (R2) was investigated in more detail. Experimental ProcedureSince HBr02 is not stable in acid solution, we have studied reaction (R2) by injecting NaBr02 (solved in 0.1 m NaOH) into aim solution of NaBr(>3 in 1 m sulfuric acid assuming that the reactionis much faster than all other reactions under consideration. Care was taken to use reagents of high purity. 1 m H2SO4 was prepared by dilution of conc. H2S04 (p.a. Merck) in bidistilled water. NaBrÜ3 (p.a. Fluka) was twice recrystallized from hot water. The absorption spectrum of solutions of NaBrC>3 in 1 m H2S04 changed significantly in the course of purification (Fig. 1); this fact is mainly due to the elimination of Br~-and BrO~-impurities. We were not able to reduce the residual 480 nm-absorption band by further recrystallization. NaBr02 was prepared by a modified procedure [7] basing on the synthesis described by Breiss [8]. The product was three times recrystallized from 0.1 m NaOH; the absorption spectrum given in Fig. 2 was found to be in excellent agreement with the spectra reported in [8,9]. The residual Br~-impurity of this product was estimated using the following procedure: alkaline solutions of NaBr02 (initial concentration 2.81 • 10~4 m) were injected into 1 m sulfuric acid and the absorption spectra of the reaction products were taken (Figure 3). In the case of curve 1, NaBr02 was used without further purification; in the case of curve 2, the alkaline solution of NaBr02 had been purified from Br~ by adding silver nitrate and removing the AgBr-precipitate by ultracentrifugation. The difference spectrum of curves 1 and 2 was found to agree with the spectrum of Br2 (curve 3). From the absorbance A =0.018 at X = 400 nm the Br2-concentration 1.1 • 10 -5 m was calculated (fiBr2 = 172 1 • mole-1 • cm-1 ).Assuming the reaction path 3 Br-+ HBr02 + 3 H+ -» 2 Br2 + 2 H20 the concentration of the Br~-impurity was estimat-0340-4811 I 80 / 1200-1354 $ 01.00/0. -Please order a reprint rather than making your own copy.

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“…As(III) + BrO" -> As(V) + Br" [19], the corresponding G (-As (I II)) may be determined. In case (b) the value adopted is the same as for the corresponding IO3 reaction with OH, for the same concentration.…”

Section: Resultsmentioning

confidence: 99%

Radiolysis of Redox Systems: Arsenite/ Bromate Ions

Dedgaonkar¹,

Μahajan²

1978

Radiochimica Acta

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Radiolysis of aqueous solutions of arsenite ions (10" 3 -10" 1 M) at pH 10 is studied in the presence of Ο, 10" 3 -1 Μ bromate. The G(-As(III)) is 2.4 for all the As(III) concentrations in the pure arsenite solution (pH 10) while in the mixture it increases with both the As(III) and BrO, concentrations. In all the cases there is a decrease in pH at the end of the irradiation. The very high G(-As(III)) (= 90-180) abruptly decreases to about 14 in each case at and below pH 7, when a relation 3.3 G(Br~) = G(-As(III)) holds. The trend remains the same whether the solution is deaerated or not. A suitable mechanism is proposed to explain the results.

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Pulsed radiolysis and flash photolysis of iodates in aqueous solution

Cited by 36 publications

References 6 publications

Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction

Radiolysis of Redox Systems: Arsenite/ Bromate Ions

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Pulsed radiolysis and flash photolysis of iodates in aqueous solution

Cited by 36 publications

References 6 publications

Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

Radiation Chemistry of Neutral Aqueous Solutions of Redox Mixtures of Thiosulphate/(i) Nitrite, (ii) Bromate and (iii) lodate Ions

Formation of BrO2 in the Belousov-Zhabotinsky-System — Investigation of the HBrO2 /BrO3 –-Reaction

Radiolysis of Redox Systems: Arsenite/ Bromate Ions

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Formation of BrO₂ in the Belousov-Zhabotinsky-System — Investigation of the HBrO₂ /BrO₃ ^–-Reaction