Bromate Research Papers - Academia.edu (original) (raw)

In the current study, an analytical technique has been optimized for the analysis of disinfection by-products (perchlorate (ClO4), bromate (BrO3), nitrate (NO3), nitrite and sulfite (SO32–) in drinking water obtained from spring, well and tap water (desalinated) sources. Methods: The ultra-performance liquid chromatography electrospray ionization mass spectrometry (UPLC ESI/MS) conditions have been optimized for oxyhalides ClO4 (isotopes, 37ClO4 and 35ClO4) andBrO3 (isotopes, 81BrO3 and 79BrO3), and inorganic anions NO3, NO2 and SO32–. Separation was achieved by BEH C18 column with methanol (75%) and water (24.99%, HCOOH 0.01%) mobile phase at flow rate 0.2 mL/min.

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- Trace contaminants, Disinfection by-products, Drinking Water, Nitrates

Significant levels of potentially carcinogenic bromate were measured in chlorinated tap drinking water in Metropolitan Manila, Philippines, using an optimized ion-chromatographic method. This method can quantify bromate in water down to 4.5 μg l−1 by employing a postcolumn reaction with acidic fuchsin and subsequent spectrophotometric detection. The concentration of bromate in tap drinking water samples collected from 21 locations in cities and municipalities within the 9-month study period ranged from 7 to 138 μg l−1. The average bromate concentration of all tap drinking water samples was 66 μg l−1 (n = 567), almost seven times greater than the current regulatory limit in the country. The levels of bromate in other water types were also determined to identify the sources of bromate found in the distribution lines and to further uncover contaminated sites. The concentration of bromate in water sourced from two rivers and two water treatment plants ranged from 15 to 80 and 12 to 101 μg l−1, respectively. Rainwater did not contribute bromate in rivers but decreased bromate level by dilution. Groundwater and wastewater samples showed bromate concentrations as high as 246 and 342 μg l−1, respectively. Bromate presence in tap drinking water can be linked to pollution in natural water bodies and the practice of using hypochlorite chemicals in addition to gaseous chlorine for water disinfection. This study established the levels, occurrence, and possible sources of bromate in local drinking water supplies.

An ion chromatographic method that employs a post-column reaction with fuchsin and spectrophotometric detection was optimized for measuring bromate (BrO3-) in water. BrO3- is converted to Br2 by sodium metabisulfite and then reacted with acidic fuchsin to form a red-colored product that strongly absorbs at 530 nm. The reaction of BrO3- and fuchsin reagent is optimum at pH 3.5 and 65 oC. The method has a limit of quantitation of 4.5 µg L-1 and is linear up to 150 µg L-1 BrO3-. Recoveries from spiked samples were high ranging from 95 to 102 % using external standard calibration and 87 to 103 % using standard addition method. Intra-batch and inter-batch reproducibility studies of the method resulted to RSD values ranging from 0.62 to 2.01 % and percent relative error of 0.12 to 2.94 % for BrO3- concentrations of 10 µg L-1 and 50 µg L-1. This method is free of interferences from common inorganic anions at levels typically found in chlorinated tap drinking water without preconcentration. The optimized method can be applied to trace analysis of bromate in chlorinated tap drinking water samples.

Worldwide water shortage increase and water quality depletion from microbial and chemical compounds, pose significant challenges for today’s water treatment industry. Both the development of new advanced oxidation technologies, but also the enhancement of existing conventional technologies is of high interest. This study tested improvements to conventional ozonation that reduce the formation of the oxidation-by-product bromate, while maintaining the effectiveness for removal emerging contaminants (atrazine). MnO4-, ClO2-, ClO2, ClO-, CH3COOO-, HSO5- or S2O8-2 with NH4+ were tested as pre-treatments to ozonation of ground water. Each oxidant and NH4+ were added in a single stage or separately prior to ozonation. To the best of our knowledge, this is the first study that has tested all the above-mentioned oxidants for the same water matrix. Based on our results, the most promising pre-treatments were MnO4--NH4+, ClO2--NH4+ and ClO2-NH4+. MnO4--NH4+ was the only pre-treatment that didn’t inhibited atrazine removal. When compared with the previously proposed Cl2/NH4+ pre-treatment, MnO4-+NH4+ was found as effective for preventing BrO3- formation, while atrazine removal was higher. In addition, MnO4-+NH4+ can be added in a single stage (compared to the 2 stage addition of Cl2/NH4+) without causing the formation of potentially harmful chlorination-by-products.

- by Henrik R Andersen
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- Ozonation, Drinking Water Treatment, Drinking Water, Bromate

The removal of bromate (BrO 3 À) as a by-product of ozonation in subsequent managed aquifer recharge (MAR) systems, specifically in anoxic nitrate (NO 3 À)-reducing zones, has so far gained little attention. In this study, batch reactors and columns were used to explore the influence of NO 3 À and increased assimilable organic carbon (AOC) due to ozonation pre-treatment on BrO 3 À removal in MAR systems. 8 m column experiments were carried out for 10 months to investigate BrO 3 À behavior in anoxic NO 3 À-reducing zones of MAR systems. Anoxic batch experiments showed that an increase of AOC promoted microbial activity and corresponding BrO 3 À removal. A drastic increase of BrO 3 À biodegradation was observed in the sudden absence of NO 3 À in both batch reactors and columns, indicating that BrO 3 À and NO 3 À competed for biodegradation by denitrifying bacteria and NO 3 À was preferred as an electron acceptor under the simultaneous presence of NO 3 À and BrO 3 À. However, within 75 days' absence of NO 3 À in the anoxic column, BrO 3 À removal gradually decreased, indicating that the presence of NO 3 À is a precondition for denitrifying bacteria to reduce BrO 3 À in NO 3 À-reducing anoxic zones. In the 8 m anoxic column setup (retention time 6 days), the BrO 3 À removal achieved levels as low as 1.3 mg/L, starting at 60 mg/L (98% removal). Taken together, BrO 3 À removal is likely to occur in vicinity of NO 3 À-reducing anoxic zones, so MAR systems following ozonation are potentially effective to remove BrO 3 À .

- by Jan Peter Hoek
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- Denitrification, Drinking Water, Managed Aquifer Recharge, Bromate

The removal of bromate (BrO 3 −) as a byproduct of ozonation in subsequent managed aquifer recharge (MAR) systems has so far gained little attention. This preliminary study with anoxic batch experiments was executed to explore the feasibility of chemical BrO 3 − reduction in Fe-reducing zones of MAR systems and to estimate potential inhibition by NO 3 −. Results show that the reaction rate was affected by initial Fe 2+ /BrO 3 − ratios and by pH. The pH dropped significantly due to the hydrolysis of Fe 3+ to hydrous ferric oxide (HFO) flocs. These HFO flocs were found to adsorb Fe 2+ , especially at high Fe 2+ /BrO 3 − ratios, whereas at low Fe 2+ /BrO 3 − ratios, the mass sum loss of BrO 3 − and Br − indicated intermediate species formation. Under MAR conditions with relatively low BrO 3 − and Fe 2+ concentrations, BrO 3 − can be reduced by naturally occurring Fe 2+ , as the extensive retention time in MAR systems will compensate for the slow reaction kinetics of low BrO 3 − and Fe 2+ concentrations. Under specific flow conditions, Fe 2+ and NO 3 − may co-occur during MAR, but NO 3 − hardly competes with BrO 3 − , since Fe 2+ prefers BrO 3 − over NO 3 −. However, it was found that when NO 3 − concentration exceeds BrO 3 − concentration by multiple orders of magnitude, NO 3 − may slightly inhibit BrO 3 − reduction by Fe 2+ .

- by Jan Peter Hoek
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- Advanced Oxidation Processes, Drinking Water, Managed Aquifer Recharge, Bromate

A new and very simple kinetic-spectrophotometric method was developed for the simultaneous determination of binary mixtures of iodate and bromate in water samples, without prior separation steps. The method is based on the mean centering of ratio kinetic profiles, allows rapid and accurate determination of bromate and iodate. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) for the simultaneous determination of binary mixtures of iodate and bromate were calculated. The results show that the method was capable of simultaneous determination of 0.05-1.50 microg mL(-1) each of iodate and bromate. The results allow simultaneous determination with the ratio 30:1-1:30 for iodate-bromate. The proposed method was successfully applied to the simultaneous determination of iodate and bromate in several water samples.

- by Abbas Afkhami
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- Engineering, Chemistry, Analytical Chemistry, Kinetics
- by Jan Peter Hoek
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- Environmental Science, Water, Advanced Oxidation Processes, Groundwater

During drinking water treatment, advanced oxidation process (AOP) with O3 and H2O2 may result in by-products, residual H2O2 and BrO3−. The water containing H2O2 and BrO3− often flows into subsequent granular activated carbon (GAC) filters. A concentrated H2O2 solution can be used as GAC modification reagent at 60 °C to improve its adsorption ability. However, whether low concentrations of H2O2 residuals from AOP can modify GAC, and the impact of H2O2 residuals on BrO3− removal by the subsequent GAC filter at ambient temperature, is unknown. This study evaluated the modification of GAC surface functional groups by residual H2O2 and its effect on BrO3− removal by GAC. Results showed that both H2O2 and BrO3− were effectively removed by virgin GAC, while pre-loaded and regenerated GACs removed H2O2 but not BrO3− anymore. At the ambient temperature 150 µmol/L H2O2 residuals consumed large amounts of functional groups, which resulted in the decrease of BrO3− removal by virgin GAC in the p...

- by liangfu wei
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- Water, Advanced Oxidation Processes, Multidisciplinary, Surface Chemistry

During drinking water treatment, advanced oxidation process (AOP) with O3 and H2O2 may result in by-products, residual H2O2 and BrO3-. The water containing H2O2 and BrO3- often flows into subsequent granular activated carbon (GAC) filters. A concentrated H2O2 solution can
be used as GAC modification reagent at 60 degree Celcius to improve its adsorption ability. However, whether low concentrations of H2O2 residuals from AOP can modify GAC, and the impact of H2O2 residuals
on BrO3- removal by the subsequent GAC filter at ambient temperature, is unknown. This study evaluated the modification of GAC surface functional groups by residual H2O2 and its effect on BrO3- removal by GAC. Results showed that both H2O2 and BrO3- were effectively removed by virgin GAC, while pre-loaded and regenerated GACs removed H2O2 but not BrO3- anymore. At
the ambient temperature 150 umol/L H2O2 residuals consumed large amounts of functional groups, which resulted in the decrease of BrO3- removal by virgin GAC in the presence of H2O2 residuals.
Redox reactions between BrO3- and surface functional groups played a dominant role in BrO3- removal by GAC, and only a small amount of BrO3- was removed by GAC adsorption. The higher
the pH, the less BrO3- removal and the more H2O2 removal was observed.