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Chii Shang - One of the best experts on this subject based on the ideXlab platform.
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Bromate Formation from Bromide Oxidation by the UV/Persulfate Process
2016Co-Authors: Jingyun Fang, Chii ShangAbstract:Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the Bromate formation increased with increasing persulfate dosage and bromide concentration. The Bromate formation was initiated and primarily driven by sulfate radicals (SO4•–) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr–) as an intermediate and Bromate as the final product. Under the test conditions, the rate of the first step driven by SO4•– is slower than that of the second step. Direct UV photolysis of HOBr/OBr– to form Bromate and the photolysis of Bromate are insignificant. The Bromate formation was similar for pH 4–7 but decreased over 90% with increasing pH from 7 to above 9. Less Bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr– and SO4•–. The extent of Bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water
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Bromate formation in bromide containing water through the cobalt mediated activation of peroxymonosulfate
Water Research, 2015Co-Authors: Zhi Chen, Chii Shang, Yingying Xiang, Li Ling, Jingyun Fang, Dionysios D DionysiouAbstract:Abstract Bromate formation in bromide-containing water through the cobalt (Co)-mediated activation of peroxymonosulfate (PMS) was investigated. Increasing the PMS dosage and the cobalt dosage increased the formation of Bromate and Bromate yields of up to 100% were recorded under the test conditions. The Bromate yield increased to a maximum as the pH rose from 2.7 to 6 before decreasing by over 90% as the pH rose further from 6 to above 9. The Bromate formation is a two-step process involving free bromine as a key intermediate and Bromate as the final product. In the first step, apart from the known oxidation of bromide to free bromine and of free bromine to Bromate by sulfate radicals (SO4 −), Co(III) produced from the oxidation of Co(II) by PMS and SO4 − also oxidizes bromide to free bromine. The contribution of Co(III) to the Bromate formation was verified with the addition of methanol and EDTA, a radical scavenger and a Co(III) ligand, respectively. In the presence of methanol, free bromine formation increased with increasing Co(II) dosage but no Bromate was detected, indicating that Co(III) oxidized bromide to form free bromine but not Bromate. In the presence of both EDTA and methanol, no free bromine or Bromate was detected, as Co(III) was stabilized by EDTA to form the CoIIIEDTA– complex, which could not oxidize bromide. Mathematical simulation further suggested that Co(III) outweighed SO4 − to oxidize bromide to free bromine. On the other hand, SO4 − is essential for the oxidation of free bromine to Bromate in the second step. In real water, the presence of NOM significantly decreased the Bromate formation but caused the brominated organic DBP formation with high quantity. This is the first study to demonstrate the significant Bromate formation in the Co/PMS system and the substantial contribution of Co(III) to the formation.
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Bromate formation from bromide oxidation by the uv persulfate process
Environmental Science & Technology, 2012Co-Authors: Jingyun Fang, Chii ShangAbstract:Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the Bromate formation increased with increasing persulfate dosage and bromide concentration. The Bromate formation was initiated and primarily driven by sulfate radicals (SO4•–) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr–) as an intermediate and Bromate as the final product. Under the test conditions, the rate of the first step driven by SO4•– is slower than that of the second step. Direct UV photolysis of HOBr/OBr– to form Bromate and the photolysis of Bromate are insignificant. The Bromate formation was similar for pH 4–7 but decreased over 90% with increasing pH from 7 to above 9. Less Bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine ato...
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the effects of operational parameters and common anions on the reactivity of zero valent iron in Bromate reduction
Chemosphere, 2007Co-Authors: Li Xie, Chii ShangAbstract:Abstract Bromate reduction by Fe(0) was investigated under various conditions in batch tests. The Bromate was primarily reduced to bromide ions with possible adsorption onto iron. Bromate reduction by Fe(0) can be described by pseudo-first-order kinetics. The differences in surface areas, numbers of reactive sites, impurities, pretreatment methods and numbers of repeated uses of iron affected the rates of Bromate reduction through reducing or accumulating a passive oxide film on the iron surface. The reduction of Bromate was significantly affected by only the dissolved oxygen content at supersaturated concentrations or by decreasing the pH from 6 to 5. Increasing the temperature increased the Bromate reduction rate, which followed the Arrhenius relationship with activation energy of 52.6 kJ mol −1 and the reduction rate increased with increased mixing rates. These observations indicate that Bromate reduction by iron is a surface-mediated process and diffusion to the surface is essential. Under the test conditions, modest inhibitory effects on Bromate reduction by Fe(0) from nitrite, chlorate and bicarbonate were observed and the inhibitory effect from phosphate was relatively larger. Enhanced reactivity of Fe(0) to Bromate was observed in the presence of nitrate or sulfate. These findings suggest that Bromate reduction by Fe(0) can be an effective method for Bromate control.
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A review on Bromate occurrence and removal strategies in water supply
Water Supply, 2006Co-Authors: Li Xie, Chii ShangAbstract:The need of disinfecting potable water to eliminate potential health risks associated with waterborne pathogens, however inevitably resulting in leaving elevated toxicity in water by forming disinfection by-products (DBPs) is being considered as one of the primary threats to human well-being. Bromate is a carcinogenic DBP mainly formed during ozonation of bromide-containing water. The current maximum contaminant level (MCL) of Bromate in the US national primary drinking water standard is set at 10 μg/L. With continuous improvements in analytical instrumentation and removal technologies, a lower MCL for Bromate is expected in the future. Current researches on Bromate control strategies involve minimizing Bromate formation (like ammonia addition) or removing Bromate after formation (like carbon adsorption), however have their own limitations. Seeking for alternative Bromate control strategies that can be used alone (or in combine with others) is of great value and in urgent need when water quality standards are getting more stringent. This paper reviews the occurrence of Bromate in water supply and evaluates the effectiveness of Bromate removal technologies applied, to advance our understanding of Bromate fate and degradation in water supply system for future study.
Jalila El Ati - One of the best experts on this subject based on the ideXlab platform.
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Potassium Bromate as a food additive: a case study of Tunisian breads
Environmental Science and Pollution Research, 2018Co-Authors: Myriam El Ati-hellal, Radhouene Doggui, Youssef Krifa, Jalila El AtiAbstract:This study is the first investigation of potassium Bromate as a food additive in Tunisian breads. In this study, levels of residual Bromate were determined in 91 commercial breads from 31 bakeries randomly selected in two Tunisian cities. In total, 13 different types of bread were analyzed using a spectrophotometric method of Bromate analysis. Bromate concentrations ranged from 5.95 to 49.31 μg g^−1, with an overall mean concentration of 19.92 μg g^−1. Significant differences were noticed between Bromate levels in breads from bakeries of the two cities ( P
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Potassium Bromate as a food additive: a case study of Tunisian breads.
Environmental science and pollution research international, 2017Co-Authors: Myriam El Ati-hellal, Radhouene Doggui, Youssef Krifa, Jalila El AtiAbstract:This study is the first investigation of potassium Bromate as a food additive in Tunisian breads. In this study, levels of residual Bromate were determined in 91 commercial breads from 31 bakeries randomly selected in two Tunisian cities. In total, 13 different types of bread were analyzed using a spectrophotometric method of Bromate analysis. Bromate concentrations ranged from 5.95 to 49.31 μg g-1, with an overall mean concentration of 19.92 μg g-1. Significant differences were noticed between Bromate levels in breads from bakeries of the two cities (P < 0.01). Based on the types of breads, Muffin contained the highest mean concentration of Bromate residue (29.92 μg g-1) as opposed to bread without salt, which had the lowest mean Bromate level (13.53 μg g-1). Compared to data available from other countries, our results showed relatively high Bromate levels, which could potentially lead to long term toxic and carcinogenic effects in the Tunisian population.
Mikhail A. Vorotyntsev - One of the best experts on this subject based on the ideXlab platform.
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Electroreduction of the Bromate Anion on a Microelectrode in Excess Acid: Solution of the Inverse Kinetic Problem
Doklady Chemistry, 2019Co-Authors: O. A. Goncharova, Dmitry V Konev, Mikhail A. Vorotyntsev, A. T. Glazkov, K. V. Lizgina, A. A. Piryazev, S. L. Koryakin, V. B. MintsevAbstract:Acidic aqueous solutions of bromic acid salts (Bromates) are promising electrolytes for redox flow batteries due to their record high power capacity and the rate of electrode reactions proceeding in the autocatalytic regime. The paper gives a comparison of the results of mathematical modeling and experimental measurements of steady-state currents of Bromate anion electroreduction in sulfuric acid medium on microelectrodes of various radii. An algorithm of solving the inverse problem suitable for determination of the key transport and kinetic process parameters was proposed and tested.
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Bromate electroreduction from sulfuric acid solution at rotating disk electrode experimental study
Electrochimica Acta, 2018Co-Authors: Alexander D. Modestov, Dmitry V Konev, Artem Evgenyevich Antipov, Mikhail M Petrov, Roman D Pichugov, Mikhail A. VorotyntsevAbstract:Abstract Our recent theoretical analysis of the Bromate reduction from acidic media at rotating disk electrode (RDE) under steady-state conditions gave astonishing predictions for the current at the plateau of the voltammogram (called “the maximal current”, jmax) which deviated cardinally from those for the previously known mechanisms of electrochemical processes. Because of the non-electroactivity of the Bromate anion itself, its transformation (without an added catalyst) can only take place owing to the redox cycle composed of the rapid reduction of bromine species (which are always present in low amounts inside strongly acidic solutions of Bromates) into bromide ions at the electrode and of the comproportionation reaction between Bromate and bromide ions inside the solution phase which regenerates bromine molecules. According to this theory, owing to the autocatalytic features of this mechanism the dependence of the maximal current density, jmax, on the RDE revolution frequency, f, is complicated. In particular, it includes a range of relatively low frequencies where the maximal current can exceed the Bromate diffusion-limited one, even for tracer amounts of bromine in the bulk solution. Another surprising conclusion of the theory is the existence of an intermediate range of frequencies (“anomalous region”) where the maximal current increases if the rotation frequency diminishes, i.e. for the weaker agitation intensity. This study presents the first experimental verification of these predictions for a series of Bromate solutions of various concentrations in 2 M sulfuric acid. Qualitative analysis of these experimental data has confirmed the principal theoretical expectations, first of all the existence of the anomalous region of frequencies. At the same time it has been found that the previously published theoretical model based on the literature data for the parameters of the system (diffusion coefficients of solution components, rate constant of the comproportionation reaction, etc.) corresponding to dilute solutions is not able to provide a quantitative interpretation of experimental data. An advanced variant of the theory has been proposed that takes into account the dependence of these parameters on the solution composition, first of all on the effect of the acid concentration. Comparison of predictions of this model with experimental data has shown their quantitative agreement, i.e. the simulated plots for the dependence, jmax(f), turned out to be close to experimental data within the whole range of frequencies available experimentally. This result represents an unambiguous proof of validity both of the principles of the underlying theory of this process and of the predictions derived within its framework.
Myriam El Ati-hellal - One of the best experts on this subject based on the ideXlab platform.
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Potassium Bromate as a food additive: a case study of Tunisian breads
Environmental Science and Pollution Research, 2018Co-Authors: Myriam El Ati-hellal, Radhouene Doggui, Youssef Krifa, Jalila El AtiAbstract:This study is the first investigation of potassium Bromate as a food additive in Tunisian breads. In this study, levels of residual Bromate were determined in 91 commercial breads from 31 bakeries randomly selected in two Tunisian cities. In total, 13 different types of bread were analyzed using a spectrophotometric method of Bromate analysis. Bromate concentrations ranged from 5.95 to 49.31 μg g^−1, with an overall mean concentration of 19.92 μg g^−1. Significant differences were noticed between Bromate levels in breads from bakeries of the two cities ( P
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Potassium Bromate as a food additive: a case study of Tunisian breads.
Environmental science and pollution research international, 2017Co-Authors: Myriam El Ati-hellal, Radhouene Doggui, Youssef Krifa, Jalila El AtiAbstract:This study is the first investigation of potassium Bromate as a food additive in Tunisian breads. In this study, levels of residual Bromate were determined in 91 commercial breads from 31 bakeries randomly selected in two Tunisian cities. In total, 13 different types of bread were analyzed using a spectrophotometric method of Bromate analysis. Bromate concentrations ranged from 5.95 to 49.31 μg g-1, with an overall mean concentration of 19.92 μg g-1. Significant differences were noticed between Bromate levels in breads from bakeries of the two cities (P < 0.01). Based on the types of breads, Muffin contained the highest mean concentration of Bromate residue (29.92 μg g-1) as opposed to bread without salt, which had the lowest mean Bromate level (13.53 μg g-1). Compared to data available from other countries, our results showed relatively high Bromate levels, which could potentially lead to long term toxic and carcinogenic effects in the Tunisian population.
Li Xie - One of the best experts on this subject based on the ideXlab platform.
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the effects of operational parameters and common anions on the reactivity of zero valent iron in Bromate reduction
Chemosphere, 2007Co-Authors: Li Xie, Chii ShangAbstract:Abstract Bromate reduction by Fe(0) was investigated under various conditions in batch tests. The Bromate was primarily reduced to bromide ions with possible adsorption onto iron. Bromate reduction by Fe(0) can be described by pseudo-first-order kinetics. The differences in surface areas, numbers of reactive sites, impurities, pretreatment methods and numbers of repeated uses of iron affected the rates of Bromate reduction through reducing or accumulating a passive oxide film on the iron surface. The reduction of Bromate was significantly affected by only the dissolved oxygen content at supersaturated concentrations or by decreasing the pH from 6 to 5. Increasing the temperature increased the Bromate reduction rate, which followed the Arrhenius relationship with activation energy of 52.6 kJ mol −1 and the reduction rate increased with increased mixing rates. These observations indicate that Bromate reduction by iron is a surface-mediated process and diffusion to the surface is essential. Under the test conditions, modest inhibitory effects on Bromate reduction by Fe(0) from nitrite, chlorate and bicarbonate were observed and the inhibitory effect from phosphate was relatively larger. Enhanced reactivity of Fe(0) to Bromate was observed in the presence of nitrate or sulfate. These findings suggest that Bromate reduction by Fe(0) can be an effective method for Bromate control.
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A review on Bromate occurrence and removal strategies in water supply
Water Supply, 2006Co-Authors: Li Xie, Chii ShangAbstract:The need of disinfecting potable water to eliminate potential health risks associated with waterborne pathogens, however inevitably resulting in leaving elevated toxicity in water by forming disinfection by-products (DBPs) is being considered as one of the primary threats to human well-being. Bromate is a carcinogenic DBP mainly formed during ozonation of bromide-containing water. The current maximum contaminant level (MCL) of Bromate in the US national primary drinking water standard is set at 10 μg/L. With continuous improvements in analytical instrumentation and removal technologies, a lower MCL for Bromate is expected in the future. Current researches on Bromate control strategies involve minimizing Bromate formation (like ammonia addition) or removing Bromate after formation (like carbon adsorption), however have their own limitations. Seeking for alternative Bromate control strategies that can be used alone (or in combine with others) is of great value and in urgent need when water quality standards are getting more stringent. This paper reviews the occurrence of Bromate in water supply and evaluates the effectiveness of Bromate removal technologies applied, to advance our understanding of Bromate fate and degradation in water supply system for future study.
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role of humic acid and quinone model compounds in Bromate reduction by zerovalent iron
Environmental Science & Technology, 2005Co-Authors: Li Xie, Chii ShangAbstract:Experiments were conducted to examine the role of humic acid and quinone model compounds in Bromate reduction by Fe(0). The reactivity of Fe(0) toward Bromate declined by a factor of 1.3−2.0 in the presence of humic acid. Evidence was obtained that the quick complexation of humic acid with iron species and its adsorption passivated the iron surface and decreased the rate of Bromate reduction by Fe(0). On the other hand, in the long run, the reduced functional groups present in humic acid were observed to regenerate Fe(II) and reduce Bromate abiotically. Compared with the case of humic acid only, the simultaneous presence of Fe(III) and humic acid significantly increased the Bromate removal rate. Fe(III)/Fe(II) acted as a catalyst in the oxidation of humic acid by Bromate. Anthraquinone-2,6-disulfonate (AQDS) and lawsone did not cause any significant effect on the Bromate reduction rate by Fe(0). However, the redox reactivity of lawsone in the presence of Fe(III) was evident, while AQDS did not show any un...
