Bromate ion formation in dark chlorination and ultraviolet/chlorination processes for bromide-containing water

Bormate （BrO3^-） is a carcinogenic chemical produced in ozonation or chlorination of bromide-containing water. Although its formation in seawater with or without sunlight has been previously investigated, the formation of bromate in dilute solutions, particularly raw water for water treatment plant, is unknown. In this article, the results of bench scale tests to measure the formation rates of bromate formation in dilute solutions, including de-ionized water and raw water from Yangtze River, were presented in dark chlorination and ultraviolet （UV）/chlorination processes. And the effects of initial pH, initial concentration of NaOCl, and UV light intensity on bromate formation in UV/chlorination of the diluted solutions were investigated. Detectable bromate was formed in dark chlorination of the two water samples with a relatively slow production rate. Under routine disinfecting conditions, the amount of formed bromate is not likely to exceed the national standards （10 μg/L）. UV irradiation enhanced the decay of free chlorine, and, simultaneously, 6.6%-32% of Br^- was oxidized to BrO3^-. And the formation of bromate exhibited three stages： rapid stage, slow stage and plateau. Under the experimental conditions （pH = 4.41-11.07, CCl2= 1.23-4.50 mg/L）, low pH and high chlorine concentration favored the generation of bromate. High light intensity promoted the production rate of bromate, but decreased its total generation amount due to acceleration of chlorine decomposition.

Effect of Fe(Ⅲ) on the bromate reduction by humic substances in aqueous solution

Humic substances are ubiquitous redox-active organic compounds of environment. In this study, experiments were conducted to determine the reduction capacity of humic acid in the man-ix of bromate and Fe（Ⅲ） solutions and the role of Fe（Ⅲ） in this redox process. The results showed that the humic acid regenerated Fe（Ⅱ） and reduced bromate abiotically. The addition of Fe（Ⅲ） could accelerate the bromate reduction rate by forming humic acid-Fe（Ⅲ） complexes. Iron species acts as electron mediator and catalyst for the bromate reduction by humic acid, in which humic acid transfers electrons to the complexed Fe（Ⅲ） to form Fe（Ⅱ）, and the regenerated Fe（Ⅱ） donate the electrons to bromate. The kinetics study on bromate reduction further indicated that bromate reduction by humic acid-Fe（Ⅲ） complexes is pH dependent. The rate decreased by 2-fold with the increase in solution pH by one unit. The reduction capacity of Aldrich humic acid was observed to be lower than that of humic acid or natural organic matter of Suwanne River, indicating that such redox process is expected to occur in the environment.

Bromate removal by activated carbon adsorption:material selection and impact factors study

Studies are conducted by using activated carbon process aimed at bromate removal from the raw water.Screening of activated carbon for bromate removal was performed in different activated carbons.GAC Merck possesses the highest iodine number and surface area,the highest number of basic groups and Vmeso,thereby contains the highest adsorption velocity and adsorption capacity.Impact factors of bromate removal on activated carbon were studied.Through static absorption experiments we studied the effect of adsorption time,pH,temperature,anions and organic matter on bromate removal.With the decrease of pH,removal of bromate enhanced,suggests that it may be possible to increase bromate reduction through pH control.The increase of temperature will be favorable to adsorption of bromate on activated carbon.Anions and organic matter can inhibit the adsorption of bromate on activated carbon through competing active sites.Bromate removal can be improved by controlling key water quality parameters.

Control of Bromate and THM Precursors Using Ozonation Combined System

Objective To investigate the feasibility of reducing THM precursors and controlling bromate taste and odor in drinking water taken from the Yellow River by an ozonation combined system. Methods The appropriate ozone dosage was determined, and then the changes of TOC, UV254 and THM formation potential （THMFP） in the combined system were evaluated. Results One mg/L ozone could effectively remove taste and odor and meet the maximum allowable bromate level in drinking water. The pre-ozonation increased THMFP, but the conventional treatment system could effectively reduce the odor. The bio-ceramic filter could partly reduce CHC13FP, but sometimes might increase CHCl2BrFP and CHClBr2FP. The biological activated carbon （BAC） filter could effectively reduce CHC13FP and CHCl2BrFP, but increase CHClBr2FP. Compared with other filters, the fresh activated carbon （FAC） filter performed better in reducing THMFP and even reduced CHClBr2FP. Conclusion The combined system can effectively reduce taste, odor, CHC13FP, and CHCl2BrFP and also bring bromate under control.

Spectrophotometric Determination of Trace Amounts of Vanadium(Ⅴ) by Means of Its Catalytic Effect on Oxidation of Azomethine-H by Bromate

A new selective and sensitive kinetic method for determination of trace amounts of vanadium(Ⅴ) (0.5～40ng/ml) based on its catalytic effect on the oxidation of azomethine H by bromate at pH 4.2 and 25 ℃ was reported and its reaction mechanism was studied.The reaction was monitored spectrophotometrically by measuring the increase in absorbance of oxidation product of azomethine H at 436 nm after a fixed time ( 5 min ).The detection limit of the method is down to 2.0×10 -10 g/ml and the relative standard deviation (RSD) for 30 ng/ml of V(Ⅴ) is 0.26 % ( n =6). The effect of foreign ions on V(Ⅴ) determination was also discussed,and the method is mostly free from interferences of other ions.The proposed method was successfully applied to the determination of trace amounts of vanadium in water samples.

NEW OSCILLATING REACTIONS CATALYZED BY TETRAMETHYLTETRAAZACYCLOTETRAENE （TIM）NICKEL（Ⅱ）COMPLEX IN BROMATE－PYRUVIC ACID ──SULFURIC ACID SYSTEM

New oscillating reaction with the participation of a macrocyclic nickel(Ⅱ) complex ion [Ni(TIM )]2+ as catalyst and pyruvic acid as organic substrate in acidic bromate medium are described' This complex ion contains the ligand: 2, 3,9, 10-tetramethyl - 1, 4, 8, 11 - tetraazacyclotetradeca - 1, 3, 8, 10 - tetraene. The [Ni (TIM ) ]2+ion can undergo oxidation reaction of Ni (Ⅱ ) Ni (Ⅲ ). Detailed research on the system's oscillation characters and influential factors is made and the mechanism is briefly discussed.

Potassium Bromate-induced Changes in the Adult Mouse Cerebellum Are Ameliorated by Vanillin

Objective The current study aimed to elucidate the effect of vanillin on behavioral changes, oxidative stress, and histopathological changes induced by potassium bromate （KBrO3）, an environmental pollutant, in the cerebellum of adult mice.Methods The animals were divided into four groups： group 1 served as a control, group 2 received KBrO3, group 3 received KBrO3 and vanillin, and group 4 received only vanillin. We then measured behavioral changes, oxidative stress, and molecular and histological changes in the cerebellum.Results We observed significant behavioral changes in KBrO3-exposed mice. When investigating redox homeostasis in the cerebellum, we found that mice treated with KBrO3 had increased lipid peroxidation and protein oxidation in the cerebellum. These effects were accompanied by decreased Na＋-K＋ and Mg2＋ ATPase activity and antioxidant enzyme gene expression when compared to the control group. Additionally, there was a significant increase in cytokine gene expression in KBrO3-treated mice. Microscopy revealed that KBrO3 intoxication resulted in numerous degenerative changes in the cerebellum that were substantially ameliorated by vanillin supplementation. Co-administration of vanillin blocked the biochemical and molecular anomalies induced by KBrO3.Conclusion Our results demonstrate that vanillin is a potential therapeutic agent for oxidative stress associated with neurodegenerative diseases.

Catalytic-kinetic spectrophotometric determination of vanadium (V) based on the Celestine blue-bromate-vanadium (V)-citric acid reaction

A novel sensitive and relatively selective kinetic method is presented for the determination of V（V） based on its catalytic effect on the oxidation reaction of Celestine blue by potassium bromate in the presence of citric acid as an activator. The reaction was monitored spectropho- tometrically by measuring the decrease in absorbance of Celestine blue at a maximum absorption wavelength of 540 nm between 0.5 and 9 min （the fixed-time method） in an H3PO4 medium at 45℃. The effect of various parameters such as concentrations of H3PO4, citric acid, potassium bromate and Celestine blue, ionic strength, reaction temperature and time on the rate of V（V） catalyzed reaction was studied. The method is free from the most interferences, especially from large amounts of V（IV）. The decrease in absorbance is proportional to the concentration of V（V） over the entire concentration range tested （0.025-1.25 lag.mL^-1） with a detection limit of 6.80 tag.L^-1 （according to statistical 3Sblank/k criterion） and a coefficient of variation （CV） of 1.78% （for ten replicate measurements at 95% confidence level）. The proposed method suffers from a few interferences such as Cr（VI） and Hg（Ⅱ） ions. The method was successfully applied to the determination of V（V） in river water, lake water, tap water, natural drinking water samples and a certified standard reference material such as SRM-1640 with satis- factory results. The vanadium contents of natural water samples were detected by using both linear calibration curve and standard addition curve methods. The recoveries of spiked vanadium （V） into the certified standard water sample were found to be quantitative, and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.

The Impacts of Different Bromide Concentrations and Advanced Oxidation Ways on the Bromate Generation

Taking reservoir water diverting from Yellow River as raw water, and using 5 m^3/h of pilot device, the impacts of different bromide concentrations and advanced oxidation ways on bmmate generation in effluent of ozone -upward flow BAC -sand filtration technology. Results showed that when bromine ion of raw water was about 100 μg/L, and ozone dosage was 2 mg/L, bromate exceeding risk existed in the effluent of ozone - upward flow BAC technology, and bromate content in the effluent reached 10 μg/L. Moreover, generation amount of bromate had certain linear rela- tionship with bromine ion of influent. Both dosing hydrogen peroxide and potassium permanganate could effectively inhibit bromate production, and there was no bromate generation in final effluent of the technology. Moreover, it also could improve the removal of major pollutants in the water by the combined process. Compared with advanced oxidation of hydrogen peroxide, potassium permanganate pre-oxidation could better control production costs.

Mechanistic Study of Ruthenium(III) Catalyzed Oxidation of Cyclohexanone by Acidic Bromate

In this work, kinetics and mechanism of Ru(III) catalyzed oxidation of cyclohexanone by acidified solution of potassium bromate has been studied. Present study employ mercuric acetate Hg (OAc)2 as a scavenger for Br¯?ion to prevent parallel oxidation by bromine. The kinetics and mechanism have also been studied in the temperature range of 30°C - 45°C. The reaction exhibits first order kinetics with respect to Ru (III), while zero order kinetics with respect to KBrO3 and HClO4. The influence of Hg(OAc)2 and ionic strength on the rate of reaction was found to be insignificant. Positive effect in the reaction mixture was also observed upon addition of chloride ion;while as the negative effect was revealed with acetic acid. A suitable mechanism in conformity with the kinetic observations has been proposed and the rate law is derived on the basis of obtained data. The various activation parameters such as energy of activation (ΔE*), Arrhenius factor (A), entropy of activation (ΔS*) were calculated from the rate measurements at 30°C, 35°C - 40°C and 45°C.

Health Risk Assessment for Bromate (BrO₃^–) Traces in Ozonated Indian Bottled Water

For this study, bromide and bromate ions in various commercial brands of Indian bottled water samples were estimated using ion chromatography. The measured mean concentration of bromide and bromate ions in water samples was found to be 28.13 μg/L and 11.17 μg/L respectively. The average level of bromate in Indian bottled water was found to be slightly higher (~ 12%) than the acceptable limits (10 μg/L) recommended by USEPA (US Environmental Protection Agency). Though, kinetically, it is predicted that 62.5% (6.25 μg/L) of bromide in bottled water is needed to convert into bromate upon ozonation to exceed the minimum acceptable limits, but the average formation of bromate determined to be only 26.77% of the predicted concentration. Bromate concentration in bottled water showed a strong correlation with bromide suggesting that its formation in water is very much influenced and controlled by bromide content. The objective of the present study was to determine the BrO3–) content of commercially available different brands of bottled drinking water in India and to estimate the health risks to population due to ingestion. Results of estimated excess cancer risk and chemical toxicity risk to Indian population due to ingestion of bottled water were presented and discussed.

X-Ray Crysatllographic and Vibrational Spectroscopic Studies of Thorium Bromate Hydrate

Th(BrO3)3·H2O single crystals were grown from its aqueous solution at room temperature. Single crystal XRD, Raman and FTIR techniques were used to investigate the crystal structure. The crystal structure was solved by Patterson method. The as grown crystals are in monoclinic system with space group P21/c. The unit cell parameters are a = 12.8555(18) ?, b = 7.8970(11) ?, c = 9.0716(10)?, α = 90°, β = 131.568° and γ = 90° and unit cell volume is 689.1(2)?3. Z = 8, R factor is 5.9. The Raman and FTIR studies indicate the lowering of symetry of bromate anion from C3V to C1. Hydrogen bonds with varying strengths are present in the crystal. The centrosymmetric space group P21/c of the crystal is confirmed by the non-coincidence of majority of Raman and IR bands.

Determination and Degradation of Potassium Bromate Content in Dough and Bread Samples Due to the Presence of Metals

Potassium bromate (PB) is used in bread making as an agent of maturation;however, it is classified as a potential carcinogen. In the present study, a rapid, simple, precise and accurate testing method has been developed to determine the level of bromate ions in bread, which is based on a reaction of bromate ions with iodide ions in acidic medium to produce iodine (I2). The absorbance of iodine (I2) was measured at 352 nm, and bromate ions reacted with iodide during the first 3 minutes after initiation of the reaction. The proposed method has been successfully applied to the determination of bromate ions in commercial bread. In this work, we found that bromate ions alone degraded at about 400°C, however, during bread making they degraded at 150°C - 200°C, this mightbe due to the presence of metals [Fe, Mg, Zn, Mn, Cu and Al] in flour which served as catalysts. In this study we found that the use of two grams (2 g) of PB per bag flour (60 kg) was safe.

Advanced oxidation of bromide-containing drinking water: A balance between bromate and trihalomethane formation control

Addition of H2O2 has been employed to repress bromate formation during ozonation of bromide-containing source water. However, the addition of H2O2 will change the oxidation pathways of organic compounds due to the generation of abundant hydroxyl radicals, which could affect the removal efficacy of trihalomethane precursors via the combination of ozone and biological activated carbon （O3-BAC）. In this study, we evaluated the effects of H2O2 addition on bromate formation and trihalomethane formation potential （THMFP） reduction during treatment of bromide-containing （97.6-129.1 μg/L） source water by the O3-BAC process. At an ozone dose of 4.2 mg/L, an H2O2/O3 （g/g） ratio of over 1.0 was required to maintain the bromate concentration below 10.0 μg/L, while a much lower H2O2/O3 ratio was sufficient for a lower ozone dose. An H2O2/O3 （g/g） ratio below 0.3 should be avoided since the bromate concentration will increase with increasing H2O2 dose below this ratio. However, the addition of H2O2 at an ozone dose of 3.2 mg/L and an H2O2/O3 ratio of 1.0 resulted in a 43% decrease in THMFP removal when compared with the O3-BAC process. The optimum H2O2/O3 （g/g） ratio for balancing bromate and trihalomethane control was about 0.7-1.0. Fractionation of organic materials showed that the addition of H2O2 decreased the removal efficacy of the hydrophilic matter fraction of DOC by ozonation and increased the reactivity of the hydrophobic fractions during formation of trihalomethane, which may be the two main reasons responsible for the decrease in THMFP reduction efficacy. Overall, this study clearly demonstrated that it is necessary to balance bromate reduction and THMFP control when adopting an H2O2 addition strategy.

Pilot study on bromate reduction in ozonation of water with low carbonate alkalinities by carbon dioxide

A pilot study was carried out to explore the application of carbon dioxide for pH depression in a bubble column and its ability to inhibit bromate formation for water with a low alkalinity.Results showed that in the absence of ammonia,CO 2 was capable of reducing bromate 38.0%–65.4% with one-unit pH depression.CO 2 caused a slightly lower bromate reduction （4.2%） than did H 2 SO 4 when the pH was depressed to 7.4,and a more a pronounced lower reduction （8.8%） when the pH was depressed to 6.9.In the presence of 0.20 mg/L-N ammonia,bromate was largely inhibited with 73.9% reduction.When the pH was depressed to 7.4,CO 2 and H 2 SO 4 showed an 11.3% and 23.5% bromate reduction respectively,demonstrating that the joint use of CO 2 and ammonia might be a plausible strategy of blocking all three bromate formation pathways.CO 2 could be applied through the aeration diffuser together with ozone gas,resulting in a similar bromate reduction compared with the premixing method through Venturi mixer.

Removal of bromate ion using powdered activated carbon

Bromate ion （BrO3-） removal from drinking water by powdered activated carbons （PACs） in bath mode was evaluated under various operational conditions. Six kinds of PACs, including wood-based carbon, fruit-based carbon, coal-based carbon, and these three carbons thermally deoxidized in a nitrogen atmosphere, were selected to investigate their capacity on BrO3- removal. With the highest zeta potential value and being richly mesoporous, coal-based carbon had a high and an excellent BrO3- adsorption efficiency. The removal content of BrO3- by per gram of coal-based carbon was 0.45 mg within 5 hr in 100 μg/L bromate solution. The surface characteristics of PACs and bromide formation revealed that both physical and chemical PACs properties simultaneously affected the adsorptionreduction process. Under acidic conditions, PACs possessed high zeta value and adequate basic groups and exhibited neutral or positive charges, promoting BrO3- adsorption-reduction on the carbon surface. Interestingly, the PACs thermally deoxidized in N2 atmosphere optimized their properties, e.g. increasing their zeta values and decreasing the oxygen content which accelerated the BrO3- removal rate. The maximum adsorption capacity of fruit-based carbon was the highest among all tested carbons （99.6 mg/g）, possibly due to its highest pore volume. Remarkably, the thermal regeneration of PACs in N2 atmosphere could completely recover the adsorption capacity of PACs. The kinetic data obtained from carbons was analyzed using pseudo second-order and intraparticle diffusion models, with results showing that the intraparticle diffusion was the more applicable model to describe adsorption of BrO3- onto PACs.

Ozone and ozone/hydrogen peroxide treatment to remove gemfibrozil and ibuprofen from treated sewage effluent: Factors influencing bromate formation

Reuse of treated sewage effluent is an important option to overcome water scarcity.Conventional wastewater treatment methods are inadequate for the removal of several persistent contaminants such as pharmaceuticals and personal care products(PPCPs).In this study the removal of ibuprofen and gemfibrozil by ozonation and ozone/hydrogen peroxide(O3/H2O2)advanced oxidation process(AOP),as well as the formation of bromate were investigated at different temperatures and pH values.Complete removal of gemfibrozil and a maximum of 80%ibuprofen removal were achieved using ozone dosage of 1.5 mg/L with O3:H2O2 ratio of 1:0.25 in the O3/H2O2 process.The effect of temperature on the removal efficiency of these two compounds was found to be negligible from 25 to 40ᵒC for both processes.pH effect from 6 to 9 was also found to be negligible for gemfibrozil removal,while ibuprofen had relatively lower removal by ozonation at pH 6 compared to higher pH values.Bromate formation was decreased to 0.012 mg/L when the pH was increased to 9.Increasing the temperature to 40ᵒC also resulted in less bromate formation which was the lowest value obtained in this study at 0.0102 mg/L.Addition of H2O2 did not affect the formation of bromate and in some cases it was found to be slightly higher compared with ozonation treatment.

Formation control of bromate and trihalomethanes during ozonation of bromide-containing water with chemical addition: Hydrogen peroxide or ammonia?

To ensure the safety of drinking water,ozone (O3) has been extensively applied in drinking water treatment plants to further remove natural organic matter (NOM).However,the surface water and groundwater near the coastal areas often contain high concentrations of bromide ion (Br-).Considering the risk of bromate (Br O3-) formation in ozonation of the sand-filtered water,the inhibitory efficiencies of hydrogen peroxide (H2O2) and ammonia(NH3) on Br O3-formation during ozonation process were compared.The addition of H2O2effectively inhibited Br O3-formation at an initial Br-concentration amended to 350μg/L.The inhibition efficiencies reached 59.6 and 100%when the mass ratio of H2O2/O3was 0.25and>0.5,respectively.The UV254and total organic carbon (TOC) also decreased after adding H2O2,while the formation potential of trihalomethanes (THMs FP) increased especially in subsequent chlorination process at a low dose of H2O2.To control the formation of both Br O3-and THMs,a relatively large dose of O3and a high ratio of H2O2/O3were generally needed.NH3addition inhibited Br O3-formation when the background ammonia nitrogen(NH3–N) concentration was low.There was no significant correlation between Br O3-inhibition efficiency and NH3dose,and a small amount of NH3–N (0.2 mg/L) could obviously inhibit Br O3-formation.The oxidation of NOM seemed unaffected by NH3addition,and the structure of NOM reflected by synchronous fluorescence (SF) scanning remained almost unchanged before and after adding NH3.Considering the formation of Br O3-and THMs,the optimal dose of NH3was suggested to be 0.5 mg/L.

Bromate formation during oxidation of bromide-containing water by the CuO catalyzed peroxymonosulfate process

Bromate formation has been found in the SO_(4)^(•−)-based oxidation processes,but previous studies primarily focused on the bromate formation in the homogeneous SO_(4)^(•−)-based oxidation processes.The kinetics and mechanisms of bromate formation are poorly understood in the heterogeneous SO_(4)^(•−)-based oxidation processes,although which have been widely studied in the eliminations of micropollutants.In this work,we found that the presence of CuO,a common heterogeneous catalyst of peroxymonosulfate(PMS),appreciably enhanced the bromate formation from the oxidation of bromide by PMS.The conversion ratio of bromide to bromate achieved over 85%within 10 min in this process.CuO was demonstrated to play a multiple role in the bromate formation:(1)catalyzed PMS to generate SO_(4)^(•−),which then oxidizes bromide to bromate;(2)catalyzed the formed free bromine to disproportionate to bromate;(3)catalyzed the formed free bromine to decomposed back into bromide.In the CuO-PMS-Br system,bromate formation increases with increasing CuO dosages,initial CuO and bromide concentrations,but decreases with increasing bicarbonate concentrations.The presence of NOM(natural organic matter)resulted in a lower formed bromate accompanied with organic bromine formation.Notably,CuO catalyzes PMS to transform more than 70%of initial bromide to bromate even after recycled used for six times.The formation of bromate in the PMS catalysis by CuO system was also confirmed in real water.

Inhibition of bromate formation by reduced graphene oxide supported cerium dioxide during ozonation of bromidecontaining water

Ozone(O3)is widely used in drinking water disinfection and wastewater treatment.However,when applied to bromide-containing water,ozone induces the formation of bromate,which is carcinogenic.Our previous study found±at graphene oxide(GO)can enhance the degradation efficiency of micropollutants during ozonation.However,in this study,GO was found to promote bromate formation during ozonation of bromide-containing waters,with bromate yields from the O3/GO process more than twice those obtained using ozone alone.The promoted bromate formation was attributed to increased hydroxyl radical production,as confirmed by the significant reduction(almost 75%)in bromate yield after adding t-butanol(TBA).Cerium oxide(less tfian 5 mg/L)supported on reduced GO(xCeO2/RGO)significantly inhibited bromate formation during ozonation compared with reduced GO alone,and the optimal Ce atomic percentage(x)was determined to be 0.36%,achieving an inhibition rate of approximately 73%.Fourier transform infrared(FT-IR)spectra indicated the transformation of GO into RGO after hydrothermal treatment,and transmission electron microscope(TEM)results showed that CeO2 nanoparticles were well dispersed on the RGO surface.The X-ray photoelectron spectroscopy(XPS)spectra results demonstrated that the Ce^3+/Ce^4+ratio in xCeO2/RGO was almost 3-4 times higher than that in pure CeO2,which might be attributed to the charge transfer effect from GO to CeO2.Furthermore,Ce+on thexCeO2/RGO surface could quench Br-and BrO-to further inhibit bromate formation.Meanwhile,0.36CeO2/RGO could also enhance the degradation efficiency of N,N-diethyl-zn-toluamide(DEET)in synthetic and reclaimed water during ozonation.