Presence Of Bromate Research Articles

Ru(III) Catalyzed Oxidation of Menthol by Bromate in Presence of Mercuric Acetate in Aqueous Acidic Medium: A Kinetic and Mechanistic Pathway

Ru(III) Catalyzed Oxidation of Menthol by Bromate in Presence of Mercuric Acetate in Aqueous Acidic Medium: A Kinetic and Mechanistic Pathway

Transcriptome analysis provides new insights into the tolerance and aerobic reduction of Shewanella decolorationis Ni1-3 to bromate.

As a possible human carcinogen, bromate is easily formed in drinking water and wastewater treatments using advanced oxidation technology. Microbial reduction is a promising method to remove bromate, but little is known about aerobic bromate reduction as well as the molecular mechanism of tolerance and reduction to bromate in bacteria. Herein, bromate reduction by isolate under aerobic conditions was reported for the first time. Shewanella decolorationis Ni1-3, isolated from an activated sludge recently, was identified to reduce bromate to bromide under both aerobic and anaerobic conditions. RNA-Seq together with differential gene expression analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed to identify that bromate triggered the expression of genes for oxidative stress protection (e.g., ohr, msrQ, dsbC, gpo, gorA, and gst), DNA damage repair (e.g., dprA, parA, and recJ), and sulfur metabolism (e.g., cysH, cysK, and cysP). However, the genes for lactate utilization (e.g., lldF and dld), nitrate reduction (e.g., napA and narG), and dissimilatory metal reduction (e.g., mtrC and omcA) were down-regulated in the presence of bromate. The results contribute to revealing the molecular mechanism of resistance and reduction in S. decolorationis Ni1-3 to bromate under aerobic conditions and clarifying the biogeochemical cycle of bromine. KEY POINTS: • Aerobic bromate reduction by pure culture was observed for the first time • Strain Ni1-3 effectively reduced bromate under both aerobic and anaerobic conditions • ROS and SOS response genes were strongly induced in the presence of bromate.

A Review on the Catalytic Hydrogenation of Bromate in Water Phase

The presence of bromate in water sources generates environmental concern due to its toxicity for humans. Diverse technologies, like membranes, ion exchange, chemical reduction, etc., can be employed to treat bromate-polluted water but they produce waste that must be treated. An alternative to these technologies can be the catalytic reduction of bromate to bromide using hydrogen as a reducing agent. In this review, we analyze the research published about this catalytic technology. Specifically, we summarize and discuss about the state of knowledge related to (1) the different metals used as catalysts for the reaction; (2) the influence of the support on the catalytic activity; (3) the characterization of the catalysts; (4) the reaction mechanisms; and (5) the influence of the water composition in the catalytic activity and in the catalyst stability. Based on published papers, we analyze the strength and weaknesses of this technique and the possibilities of using this reaction for the treatment of bromate-polluted water as a sustainable process.

Manipulating the Polymerization of 3,5-Diaminobenzoic Acid with a Bromate Oscillator

Manifestation of the properties of 3,5-diaminobenzoic acid polymer film was explored by polymerizing 3,5-diaminobenzoic acid in the presence of bromate. Depending on the initial concentration of bromate, the 3,5-diaminobenzoic acid solution was observed to transit from steady to oscillatory evolution in a batch reactor. The thus-fabricated film on Au electrodes exhibited different activities toward the electrochemical oxidation of pyrocatechol. The film synthesized at nonoscillatory conditions has a primary oxidation peak of pyrocatechol at about 0.20 V (vs Hg/Hg2SO4 electrode), as opposed to 0.0 V with the film that was prepared under oscillatory conditions. A phase diagram in the bromate–sulfuric acid phase was constructed to demonstrate the influence of each parameter on the emergence of oscillatory behavior in the 3,5-diaminobenzoic acid system. Experiments showed that an increase in the concentrations of sulfuric acid and bromate greatly increased the frequency and reduced the induction period of the...

Bromate in Bottled Water – Potential Hazard for Human Health

In the International Agency for Research on Cancer (IARC) classification, bro­mates (by-products of water treatment) are categorized as Class 2B carcino­gens; i.e., substances that are possibly carcinogenic to humans. The maximal concentration of bromate in drinking water must not be higher than 10 μg/L, while the WHO recommends that bromate levels should be as low as possible. Investigations undertaken in several countries have revealed the presence of bromate in bottled water, too. The main factor responsible for the presence of bromate is ozonation during the manufacturing process or bromate-contam­inated substances used in the water disinfection.The regulations currently in force in Poland forbid the addition of bacteriostatic agents and the application of treatment processes that alter the microflora in water. On the other hand, raw water can be filtered, aerated, or treated with air enriched in ozone – although only in the amounts required to remove iron, manganese, arsenic compounds, and sulfides. However, during the manufacturing process, bottled water may be exposed to ozone from electric-powered ionizers used in the process of the dry-cleaning of bottles or PET preforms. The maximal admissible bromate contents in bottled water is 3 μg/L. The cur­rent regulations in Poland effectively reduce hazards due to the presence of bromate in water. However, the results of investigations undertaken in other countries indicate that this aspect should be brought to the attention of both water manufacturers and regulatory bodies.

Sensitive voltammetric determination of bromate by using ion-exchange property of a Sn(II)-clinoptilolite-modified carbon paste electrode

A modified carbon paste electrode with Sn(II)-exchanged clinoptilolite nanoparticles (CNP-Sn(II)-CPE) showed voltammetric current (in cyclic voltammetry (CV)) for Sn(II)/Sn(IV) in sulfuric acid electrolyte (pH 2). The peak current was decreased when bromate was added to the solution. Hence, this decrease was used for indirect voltammetric determination of bromate. In designed experiments using response surface methodology (RSM) approach in square-wave voltammetry (SqW), strong acidic pH values (pH 1.8–2.5) caused an increased SqW voltammetric response, because such pH values bring sufficient Sn(II) as the electroactive species at the electrode surface via ion-exchange process. The optimal variables obtained are sulfuric acid as supporting electrolyte at pH 1.80, modifier% at 25, amplitude at 498.4 mV, step potential at 5.4 mV, and frequency at 25 Hz. The peak current of Sn(II)/Sn(IV) redox pair was inversely proportionate to the concentration of bromate. Hence, ΔI (difference in peak current in the absence and presence of bromate) was proportionally increased with increasing the concentration of bromate in the range of 5.00 to 100.00 μmol L−1 with a detection limit of 0.06 μmol L−1 bromate. The effect of some strong oxidizing agents was studied, and the results showed that when such agents are present at levels of 2.5 to 5 times greater than the bromate in the solution, they can cause a maximum error of 3% in the determination of bromate in sulfuric acid electrolyte at pH 2.5.

Effects of Bromate on the Growth and Physiological Characteristics of Chlorella vulgaris

The effects of bromate on the growth and physiological characteristics of Chlorella vulgaris were investigated via the static exposure experiments and tested by flow cytometry. The results showed that when Chlorella vulgaris was continuously exposed to bromate for 96 h at 8 mmol·L-1, the specific growth rates and cell membrane integrity decreased significantly, while the esterase activity, mitochondrial membrane potential and reactive oxygen species (ROS) increased significantly. The membrane-damaged cells could be found from the scanning electron microscopy analysis. It could be identified that ROS were overproduced in presence of bromate, which could not be eliminated by Chlorella vulgaris in time through self-regulation. The excess ROS could lead to abnormal situation of cell membrane integrity, esterase activity and mitochondrial membrane potential, disorder of physiology function and damage of cell structure. It could be concluded that Chlorella vulgaris died or their growth was inhibited by the existence of bromate.

Photocatalytic Reduction Activity of 001 TiO2 Codoped with F and Fe under Visible Light for Bromate Removal

The presence of bromate in water is a well-known problem because of its toxic effects on human health, particularly its carcinogenic potential. Photocatalytic reduction is an attractive process for bromate removal. F- and Fe-codoped TiO2 (F-Fe-TiO2) with a {001} facet was successfully prepared, and its bromate-removal activity under visible light was examined. The microstructure, morphology, and chemical state of the doping elements and the optical property of the photocatalysts were examined using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), photoluminescence spectroscopy (PLS), and UV-Vis diffuse reflectance spectra (DRS). The results indicate that the optical properties of F-Fe-TiO2 with the {001} facet and cuboid morphology were obviously improved and its photocatalytic activity was significantly enhanced. The bromate solution of 100 μg/L was thoroughly removed with 0.5 g/L dosage of 1.0% F- and 0.08% Fe-codoped TiO2 composite within 1 hour under visible light.

Determination of trace amount of formaldehyde base on a bromate-Malachite Green system

A novel catalytic kinetic spectrophotometric method for determination of trace amount of formaldehyde (FA) has been established, based on catalytic effect of trace amount of FA on the oxidation of Malachite Green (MG) by potassium bromate in presence of sulfuric acid medium, and was reported for the first time. The method was monitored by measuring the decrease in absorbance of MG at 617nm and allowed a precise determination of FA in the range of 0.003–0.08μgmL−1, with a limit of detection down to 1ngmL−1. The relative standard deviation of 10 replicate measurements was 1.63%. The method developed was approved to be sensitive, selective and accurate, and adopted to determinate free FA in samples directly with good accuracy and reproducibility.

Bromate removal by anaerobic bacterial community: Mechanism and phylogenetic characterization

A highly bromate resistant bacterial community and with ability for bromate removal was obtained from a sulphate-reducing bacteria enrichment consortium. This community was able to remove 96% of bromate and 99% of sulphate from an aqueous solution containing 40μM bromate and 10mM sulphate. Moreover, 93% of bromate was removed in the absence of sulphate. Under this condition bromate was reduced stoichiometrically to bromide. However, in the presence of sulphate only 88% of bromate was reduced to bromide. Although, bromate removal was not affected by the absence of sulphate, this anion promoted a modification on the structure of the bacterial community. Phylogenetic analysis of 16S rRNA gene showed that the community grown in the presence of bromate and sulphate was mainly composed by bacteria closely to Clostridium and Citrobacter genera, while the community grown in the absence of sulphate was predominantly composed by Clostridium genus. It is the first time that Clostridium and Citrobacter genera are reported as having bromate removal ability. Furthermore, bromate removal by the consortium predominantly composed by Clostridium and Citrobacter genera occurred by enzymatic reduction and by extracellular metabolic products, while the enzymatic process was the only mechanism involved in bromate removal by the consortium mainly composed by Clostridium genus.

Catalytic-adsorptive stripping voltammetric determination of ultra-trace iridium(III). Application to fresh- and sea-water

An extremely sensitive stripping voltammetric procedure for ultra-trace determination of iridium(III) is reported. The method is based on the interfacial accumulation of the iridium(III)–CTAB complex onto the glassy carbon electrode, followed by the catalytic reduction of the adsorbed complex in the presence of bromate. 0.3molL−1 acetate buffer pH 4.7+6.9×10−2molL−1 NaBrO3+2.7×10−5molL−1 cetyltrimethylammonium bromide (CTAB)+0.2molL−1 KCl was employed as the supporting electrolyte.The analytical procedure was verified by the analysis of the standard reference materials: Sea Water BCR-CRM 403 and Fresh Water NIST-SRM 1643d.The accuracy, expressed as relative error e%, was satisfactory, being lower than 6%, while precision as repeatability, expressed as relative standard deviation sr%, was generally lower than 5%. The limit of detection was of the order of 2–3ngL−1.Once set up on the standard reference materials, the analytical procedure was transferred and applied to superficial water sampled in proximity to superhighway and in the Po river mouth area.

Potassium Bromate as an Oxidizing Agent in a Titania-Based Ru CMP Slurry

Ru chemical mechanical planarization CMP was studied in slurries containing titania and potassium bromate at different pHvalues, showing that the Ru removal rate is enhanced at pH 2 or less. Potentiodynamic polarization studies indicate that thecorrosion current is enhanced in the presence of bromate, while the static etch rate experiments show that the etch rate is low.Potassium bromate increases Ru removal only at anodic potentials or during mechanical abrasion. Studies at different concentra-tions of abrasive and oxidizing agent reveal that the removal rate enhancement saturates at 0.75 mM bromate and 4 wt % titania.© 2010 The Electrochemical Society. DOI: 10.1149/1.3481948 All rights reserved.Manuscript submitted July 6, 2010; revised manuscript received July 27, 2010. Published August 31, 2010.

A novel indicator reaction for the catalytic determination of V(V) at ppb levels by the kinetic spectrophotometric method

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 Ponceau Xylydine by potassium bromate in presence of 5-sulfosalicylic acid (SSA) as activator. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Ponceau Xylydine at 640 nm between 0.5 to 7 min (the fixed time method) in H3PO4 medium at 25oC. The effect of various parameters such as concentrations of H3PO4, SSA, bromate and Ponceau Xylydine, temperature and ionic strength on the rate of net reaction were studied. The method is free from 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 (1–15 ng mL−1) with a detection limit of 0.46 ng mL–1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.8% (for ten replicate measurement at 95% confidence level).

A novel indicator reaction for the catalytic determination of V(V) at ppb levels by the kinetic spectrophotometric method

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 Ponceau Xylydine by potassium bromate in presence of 5-sulfosalicylic acid (SSA) as activator. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Ponceau Xylydine at 640 nm between 0.5 to 7 min (the fixed time method) in H3PO4 medium at 25oC. The effect of various parameters such as concentrations of H3PO4, SSA, bromate and Ponceau Xylydine, temperature and ionic strength on the rate of net reaction were studied. The method is free from 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 (1-15 ng mL−1) with a detection limit of 0.46 ng mL-1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.8% (for ten replicate measurement at 95% confidence level). The proposed method suffers few interferences such as Cr(VI) and Hg(II) ions. The method was successfully applied to the determination of V(V) in tap water, drinking water, bottled mineral water samples and a certified standard reference material such as SRM-1640 with satisfactory results. The vanadium contents of water samples were also determined by FAAS for a comparison. The recovery of spiked vanadium(V) was 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.

Fluorescence Detection-FIA for ppb Levels of Bromate with Trifluoperazine

The fluorescence of tifluoperazine at EX:300 nm and EM:485 nm was changed into non-fluorescent substance in the presence of bromate under acidic conditions, and the fluorescence detection-FIA of trace amounts of the bromate was developed using this phenomenon. In the concentration range of 1-15 μg L -1 , the bromate analysis was able to obtain a good straight line and eighteen samples per hour were measured. For 7.5 μg L -1 of bromate, the relative standard deviation(RSD) was 2.03 %(n=5) and the detection limit (3σ) was 1.47 μg L -1 .

Temperature influence on the malonic acid decomposition in the Belousov-Zhabotinsky reaction

The kinetic investigations of the malonic acid decomposition (8.00 × 10−3 mol dm−3 ≤ [CH2(COOH)2]0 ≤ 4.30 × 10−2 mol dm−3) in the Belousov-Zhabotinsky (BZ) system in the presence of bromate, bromide, sulfuric acid and cerium sulfate, were performed in the isothermal closed well stirred reactor at different temperatures (25.0°C ≤ T ≤ 45.0°C). The formal kinetics of the overall BZ reaction, and particularly kinetics in characteristic periods of BZ reaction, based on the analyses of the bromide oscillograms, was accomplished. The evolution as well as the rate constants and the apparent activation energies of the reactions, which exist in the preoscillatory and oscillatory periods, are also successfully calculated by numerical simulations. Simulations are based on the model including the Br2O species.

Spectrophotometric determination of vanadium(IV, V) in chloride-rich samples by its catalytic effect on the oxidative coupling of N,N-diphenylhydrazine with chromotropic acid

A kinetic method has been developed for the spectrophotometric determination of subnanogram per milliliter levels of vanadium in the presence of large amounts of sodium chloride. The method is based on the catalytic effect of vanadium(V) on the oxidative coupling of N,N-diphenylhydrazine with chromotropic acid in the presence of bromate. In this reaction, chloride enhanced the catalysis of vanadium(V). Vanadium(IV) could be also determined because of its oxidation by bromate. By measuring the change in absorbance of the dye produced at a fixed time, vanadium(IV) and vanadium(V) in the range of 0.01–0.2 ng mL−1 could be determined. The relative standard deviation was 2.0% for ten determinations of 0.1 ng mL−1 vanadium(V). Interferences from diverse ions could be suppressed by the use of ethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid) as a masking agent. The method was successfully applied to the determination of vanadium(IV) and vanadium(V) in chloride-rich samples.

Malonic acid concentration as a control parameter in the kinetic analysis of the Belousov–Zhabotinsky reaction under batch conditions

The influence of the initial malonic acid concentration [MA]0 (8.00 x 10(-3) < or = [MA]0 < or = 4.30 x 10(-2) mol dm(-3)) in the presence of bromate (6.20 x 10(-2) mol dm(-3)), bromide (1.50 x 10(-5) mol dm(-3)), sulfuric acid (1.00 mol dm(-3)) and cerium sulfate (2.50 x 10(-3) mol dm(-3)) on the dynamics and the kinetics of the Belousov-Zhabotinsky (BZ) reactions was examined under batch conditions at 30.0 degrees C. The kinetics of the BZ reaction was analyzed by the earlier proposed method convenient for the examinations of the oscillatory reactions. In the defined region of parameters where oscillograms with only large-amplitude relaxation oscillations appeared, the pseudo-first order of the overall malonic acid decomposition with a corresponding rate constant of 2.14 x 10(-2) min(-1) was established. The numerical results on the dynamics and kinetics of the BZ reaction, carried out by the known skeleton model including the Br2O species, were in good agreement with the experimental ones. The already found saddle node infinite period (SNIPER) bifurcation point in transition from a stable quasi-steady state to periodic orbits and vice versa is confirmed by both experimental and numerical investigations of the system under consideration. Namely, the large-amplitude relaxation oscillations with increasing periods between oscillations in approaching the bifurcation points at the beginning and the end of the oscillatory domain, together with excitability of the stable quasi-steady states in their vicinity are obtained.

A simple and sensitive chromium speciation procedure by hyphenating flow injection on-line preconcentration with catalytic spectrophotometry

A high sensitive chromium speciation procedure based on spectrophotometric detection was developed by coupling flow injection on-line preconcentration with a catalytic indicator reaction. Chromium(VI) is retained on a mini-column packed with polystyrene anion exchange resin (strong basic 717 resin), which was afterwards eluted with a small volume of NaNO 3 solution. The eluted Cr(VI) is then directed to catalyze the decoloration of alizarin cyanine green (ACG) in the presence of bromate as oxidizing reagent, and the absorbance change is proportional to the concentration of Cr(VI). With a sampling volume of 12 ml and a loading time of 120 s, an enrichment factor of 26.5 was achieved for the preconcentration. The most distinct feature of this procedure is characterized by its overall detection limit, i.e., 50 ng l −1, which is much superior to those achieved by FAAS, and comparable to those obtained by inductively coupled plasma mass spectrometry (ICPMS) and electrothermal atomic absorption spectrometry (ETAAS). The procedure was validated with a certified reference material. It was also applied to the speciation of chromium in a series of surface water samples.

Ru(Iii) Catalysed Oxidation of Diethanolamine and Triethanolamine by Br(V) in Presence of Perchloric Acid

Kinetics and mechanism of oxidation of diethanolamine (DEA) and triethanolamine (TEA) by potassium bromate in presence of ruthenium(III) chloride as homogeneous catalyst in perchloric acid medium have been investigated. First order kinetics with respect to each of [KBrO3] and [Ru(III) chloride] was observed in the oxidation of both DEA and TEA. With about eight-fold variation in [DEA] and 10-fold variation in [TEA], first order kinetics in [substrate] was observed up to nearly 3-fold variation in [DEA] and 5-fold variation in [TEA]. Kinetics with negative effect of [substrate] became more complex in both cases when a significant decrease in pseudo first order rate constant was observed at their higher concentrations. Inverse fractional order in [H+] was noted throughout its 10-fold variation. Variation in [Hg(OAc)2], [Cl–] and ionic strength (μ) of the medium did not bring about any significant change on the rate of reaction. The values of rate constants observed at four different temperatures were utilised to calculate the activation parameters. Acetic acid and ammonia have been identified as main oxidation products of the reactions. A suitable mechanism involving the formation of a complex between [Ru(III)–aminoalcohol] complex and bromate ion prior to the rate-determining step is proposed.