Search

The mixed Fe(II)/Fe(III) mineral magnetite [Fe3O4] of various stoichiometric and non‐stoichiometric compositions have been reported in Martian soils and rocks by several rover missions. Magnetite is an important paleomagnetic indicator mineral and can serve as a 'biogeobattery' as a consequence of its magnetic properties and the mixed valence state of iron in its structure. Here, we assess the extent of oxidative weathering of magnetite in presence of chlorate and bromate containing solutions that are likely important oxidants on Mars. Oxyhalogen species, chlorate and bromate, produced non‐stoichiometric magnetite [Fe(II)/Fe(III) < 0.5] in Mars‐relevant, near‐neutral pH fluids; no other ferric minerals were produced. The same results were observed in highly acidic fluids with or without oxyhalogens. Owing to its resistance to extensive oxidation, magnetite can serve as an important archive of geochemical, paleomagnetic, and astrobiological information in samples that will be returned by the Mars Sample Return mission. Plain Language Summary: Magnetite is an iron oxide that contains both Fe(II) and Fe(III) in its crystal structure. The Fe(II) to Fe(III) ratio in an ideal (i.e., stoichiometric) magnetite is 0.5, that decreases as Fe(II) in its structure oxidizes to Fe(III) thereby forming non‐ideal (i.e., non‐stoichiometric) magnetite. Owing to its unique structure, magnetite can serve as an important paleomagnetic indicator mineral and a source of energy for microorganisms. Therefore, understanding the survivability of magnetite in presence of the harsh oxidizing chemical environment on Mars is important. Here, we conduct laboratory experiments in Mars‐like fluids to test the reactivity of magnetite in presence of strong and effective oxidants that have previously been shown to be active on Mars. Our results show that magnetite is resistant to extensive oxidation in presence of chlorate and bromate solutions to an extent that is much greater than other Fe(II) minerals like iron sulfides, and forms non‐stoichiometric magnetite making it a useful target for analyses of samples from the Mars Sample Return mission aimed at understanding Mars' magnetic history and habitability. Key Points: Magnetite shows resistance to oxidation by oxyhalogen compounds (chlorate and bromate) in Mars‐relevant fluidsNon‐stoichiometric magnetite on Mars may be formed by aqueous alteration of stoichiometric magnetite by oxyhalogen compoundsMagnetite likely preserves geochemical, paleomagnetic and astrobiological information and is an important target mineral in Mars return samples [ABSTRACT FROM AUTHOR]

Chlorate (ClO3-) is a toxic oxyanion pollutant from industrial wastes, agricultural applications, drinking water disinfection, and wastewater treatment. Catalytic reduction of ClO3- using palladium (Pd) nanoparticle catalysts exhibited sluggish kinetics. This work demonstrates an 18-fold activity enhancement by integrating earth-abundant vanadium (V) into the common Pd/C catalyst. X-ray photoelectron spectroscopy and electrochemical studies indicated that VV and VIV precursors are reduced to VIII in the aqueous phase (rather than immobilized on the carbon support) by Pd-activated H2. The VIII/IV redox cycle is the predominant mechanism for the ClO3- reduction. Further reduction of chlorine intermediates to Cl- could proceed via VIII/IV and VIV/V redox cycles or direct reduction by Pd/C. To capture the potentially toxic V metal from the treated solution, we adjusted the pH from 3 to 8 after the reaction, which completely immobilized VIII onto Pd/C for catalyst recycling. The enhanced performance of reductive catalysis using a Group 5 metal adds to the diversity of transition metals (e.g., Cr, Mo, Re, Fe, and Ru in Groups 6-8) for water pollutant treatment via various unique mechanisms.

Fully halogenated compounds are difficult to remediate by in situ chemical oxidation (ISCO) because carbon-halogen bonds react very slowly with the species that typically initiate contaminant transformation: sulfate radical (SO4•-) and hydroxyl radical (•OH). To enable the remediation of this class of contaminants by persulfate (S2O82-)-based ISCO, we employed a two-phase process to dehalogenate and oxidize a representative halogenated compound (i.e., hexachloroethane). In the first phase, a relatively high concentration of ethanol (1.8 M) was added, along with concentrations of S2O82- that are typically used for ISCO (i.e., 450 mM). Hexachloroethane underwent rapid dehalogenation when carbon-centered radicals produced by the reaction of ethanol and radicals formed during S2O82- decomposition reacted with carbon-halogen bonds. Unlike conventional ISCO treatment, hexachloroethane transformation and S2O82- decomposition took place on the time scale of days without external heating or base addition. The presence of O2, Cl-, and NO3- delayed the onset of hexachloroethane transformation when low concentrations of S2O82- (10 mM) were used, but these solutes had negligible effects when S2O82- was present at concentrations typical of in situ remediation (450 mM). The second phase of the reaction was initiated after most of the ethanol had been depleted when thermolytic S2O82- decomposition resulted in production of SO4•- that oxidized the partially dehalogenated transformation products. With proper precautions, S2O82--based ISCO with ethanol could be a useful remediation technology for sites contaminated with fully halogenated compounds.

Perchlorate and chlorate are present in various extraterrestrial celestial bodies throughout the solar system, such as Mars, the moon, and asteroids. To date, the origin mechanisms of perchlorate and chlorate on the Martian surface have been well-established; however, relatively little attention has been cast to airless bodies. Here, we experimentally investigated the potential oxidation mechanisms of chloride to chlorate and perchlorate, such as ultraviolet irradiation under H2O- and O2-free conditions and mechanical pulverization processes. Individual minerals, olivine, pyroxene, ilmenite, magnetite, TiO2 and anhydrous ferric sulfate, and lunar regolith simulants (low Ti, CLRS-1; high-Ti, CLRS-2) and their metallic iron (Fe0) bearing counterparts were examined. We found that pulverization of dry matrix material-halite mixtures, even in the presence of O2, does not necessarily lead to perchlorate and chlorate formation without involving water. Under photocatalytic and H2O- and O2-free conditions, olivine and pyroxene can produce oxychlorine (ClOx−) species, although the yields were orders of magnitude lower than those under Martian-relevant conditions. Nanophase-Fe0 particles in the lunar regolith and the common photocatalyst TiO2 can facilitate the ClOx− formation, but their yields were lower than those with olivine. The oxides ilmenite and magnetite did not efficiently contribute to ClOx− production. Our results highlight the critical role of H2O in the oxidation chloride to chlorate and perchlorate, and provide essential insights into the environmental influence on the formation of oxychlorine species on different celestial bodies. [ABSTRACT FROM AUTHOR]

In an effort to reduce the occurrence of chlorine derived residues such as chlorate and trichloromethane (TCM) in milk and ultimately in dairy products, 'chlorine-free' cleaning of milking equipment became compulsory in the Republic of Ireland (ROI) from January 2021. While data exists on TCM levels in bulk tank milk, little is known about the prominence and typical levels (mg/kg) of chlorate residue in bulk tank milk. To address this, 3625 bulk milk samples were collected from six milk processors and were analysed for chlorate and TCM residues across 2020 and 2021, with 2020 representing a period before chlorine-free cleaning was introduced and 2021 being the period after chlorine removal. In 2020, 15% of the samples analysed had detectable levels of chlorate (0.0020–1.6 mg/kg), but this reduced to 8% in 2021 (0.0020–3.9 mg/kg), following the introduction of 'chlorine-free' cleaning. Chlorate and TCM residues have not been totally eliminated because sources of residue other than cleaning chemicals exist, i.e., chlorinated water. [ABSTRACT FROM AUTHOR]

Abstract The mixed Fe(II)/Fe(III) mineral magnetite [Fe3O4] of various stoichiometric and non‐stoichiometric compositions have been reported in Martian soils and rocks by several rover missions. Magnetite is an important paleomagnetic indicator mineral and can serve as a ‘biogeobattery’ as a consequence of its magnetic properties and the mixed valence state of iron in its structure. Here, we assess the extent of oxidative weathering of magnetite in presence of chlorate and bromate containing solutions that are likely important oxidants on Mars. Oxyhalogen species, chlorate and bromate, produced non‐stoichiometric magnetite [Fe(II)/Fe(III)

In an effort to reduce the occurrence of chlorine derived residues such as chlorate and trichloromethane (TCM) in milk and ultimately in dairy products, ‘chlorine-free’ cleaning of milking equipment became compulsory in the Republic of Ireland (ROI) from January 2021. While data exists on TCM levels in bulk tank milk, little is known about the prominence and typical levels (mg/kg) of chlorate residue in bulk tank milk. To address this, 3625 bulk milk samples were collected from six milk processors and were analysed for chlorate and TCM residues across 2020 and 2021, with 2020 representing a period before chlorine-free cleaning was introduced and 2021 being the period after chlorine removal. In 2020, 15% of the samples analysed had detectable levels of chlorate (0.0020–1.6 mg/kg), but this reduced to 8% in 2021 (0.0020–3.9 mg/kg), following the introduction of ‘chlorine-free’ cleaning. Chlorate and TCM residues have not been totally eliminated because sources of residue other than cleaning chemicals exist, i.e., chlorinated water.

ObjectiveA method was developed to simultaneously determine chlorate and perchlorate in vegetables and fruits using ultra-performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry （UPLC-Qtrap MS）.MethodsThe chlorate and perchlorate residues in samples were extracted using acetonitrile and water， and the supernatant was purified using GCB and PSA. The analytes were separated on a Waters Anionic Polar Pesticide （100 mm×2.1 mm， 5 µm） column using a mobile phase comprising acetonitrile and 20 mmol/L ammonium formate solution and detected using UPLC-Qtrap MS. The internal standard method was used for quantification.ResultsThe linear relationship of chlorate and perchlorate ranged from 2.0-200 and 0.5-100 µg/L， with correlation coefficients >0.999. The limits of detection were 0.006 and 0.001 mg/kg. The recoveries in spiked samples ranged from 83.3%-105.5%， and the relative standard deviations ranged from 0.97%-3.80%.ConclusionA rapid， simple， accurate， and precise method was developed for the simultaneous analysis of chlorate and perchlorate in vegetables and fruits.

Adding CrIII or AlIII salts into the water suspension of platinum group metal (PGM) catalysts accelerated oxyanion pollutant reduction by up to 600%. Our initial attempts of adding K2CrVIO4, K2CrVI2O7, or KCrIII(SO4)2 into Pd/C enhanced BrO3- reduction with 1 atm H2 by 6-fold. Instrument characterizations and kinetic explorations collectively confirmed the immobilization of reduced CrVI as CrIII(OH)3 on the catalyst surface. This process altered the ζ-potentials from negative to positive, thus substantially enhancing the Langmuir-Hinshelwood adsorption equilibrium constant for BrO3- onto Pd/C by 37-fold. Adding AlIII(OH)3 from alum at pH 7 achieved similar enhancements. The Cr-Pd/C and Al-Pd/C showed top-tier efficiency of catalytic performance (normalized with Pd dosage) among all the reported Pd catalysts on conventional and nanostructured support materials. The strategy of adding inert metal hydroxides works for diverse PGMs (palladium and rhodium), substrates (BrO3- and ClO3-), and support materials (carbon, alumina, and silica). This work shows a simple, inexpensive, and effective example of enhancing catalyst activity and saving PGMs for environmental applications.

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combined action of sulfate and chlorine salts erodes concrete structures in coastal and saline-alkali zones. The induced fractures under load also accelerate the deterioration of concrete. In this study, ion erosion tests of fractured coal-gasified ash slag (FC-GAS) concrete under dry-wet cyclic conditions were performed using ordinary concrete as the reference. The mass loss rates, the relative dynamic moduli of elasticity, and the distribution patterns of chlorine and sulfate ions of specimens in erosive environments of single sulfate salt, single chlorine salt, and mixed sulfate and chlorine salts were measured. The deterioration mechanism of FC-GAS concrete under coupled erosion by sulfate and chlorine salts was explored with SEM and XRD techniques. By introducing the influence coefficient and deterioration coefficient of the fracture width of FC-GAS concrete, a modified model describing the diffusion behavior of chlorine ions in FC-GAS concrete was established. The results show that for the concrete specimens after erosion in sulfate salt and the mixture of sulfate and chlorine salts, the mass and the relative dynamic modulus of elasticity first increased and then dropped. The deterioration of the concrete performance after soaking in the mixed solution was significantly lower than that of the specimen after dry-wet cycles in the single solution. The formation of fractures accelerated ion erosion. Chlorine and sulfate ions in the mixed solution could inhibit the diffusion of other ions. The diffraction peak strengths of the erosion products of the specimen after dry-wet cycles in the mixed solution were significantly reduced. The results calculated by the proposed modified model on the diffusion of chlorine ions in FC-GAS concrete agreed with the experimental results.

The potential for chlorinated water to cause chlorate contamination of milk was evaluated at both laboratory and field level. It was found that for such contamination to occur, direct contact of water and milk was necessary. To minimise the opportunity for chlorinated water to cause chlorate contamination of milk, it is vital to ensure that milk handling equipment is engineered to provide for proper drainage of water and that all necessary steps are taken to prevent the adulteration of milk with water. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chlorate and perchlorate are emerging pollutants that may interfere with thyroid function. Since they are highly water soluble, chlorate and perchlorate in tea leaves cause health concerns but have scarcely been studied. In this study, chlorate and perchlorate concentrations in 216 tea samples from different regions of China were determined. Perchlorate was detected in all the samples with a median concentration of 44.1 μg kg−1, while the chlorate detection frequency was 15.7%. We observed regional differences in perchlorate contents in tea leaves, with the highest quantity found in the central region of China. Except for dark tea, the concentration of perchlorate in tea infusions decreased with the increased number of times the tea leaves were brewed. The hazard quotients (HQs) of chlorate and perchlorate in all the samples were less than 1, suggesting negligible health risks caused by these pollutants from tea consumption. To the best of our knowledge, this is the first study to investigate chlorate and perchlorate contamination in tea infusions by simulating brewing behavior. [ABSTRACT FROM AUTHOR]

ObjectiveTo understand the pollution level of perchlorate and chlorate in infant formula milk powder in Inner Mongolia evaluate the dietary intake risk of perchlorate and chlorate in infants， and provide a scientific basis for guiding the healthy diet of infants in Inner Mongolia.MethodsA total of 539 infant formula milk powder sold in each segment in Inner Mongolia were collected， and 254 milk powder flushing water （drinking water that may be used in the flushing and mixing of milk powder） were collected. The contents of perchlorate and chlorate in infant formula milk powder and milk powder washing and mixing water were detected by ultra-performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. Based on the consumption data of infants and young children in Inner Mongolia in the 2015 China Infant Food Consumption survey data， the risk of dietary intake of perchlorate and chlorate in infant formula milk powder in Inner Mongolia was calculated by simple distribution assessment and cumulative exposure assessment.ResultsThe overall detection rate of perchlorate in infant formula milk powder was 92.39% （498/539）. The detection value was not detected up to 89.30 μg/kg， with an average of 14.45 μg/kg and a median of 9.00 μg/kg. The overall detection rate of chlorate was 73.10% （394/539）， and the detection value was not detected up to 1 061.00 μg/kg， with an average of 93.25 μg/kg and a median of 45.50 μg/kg. The overall detection rate of perchlorate in milk powder was 67.32% （171/254）， and the detection value was not detected up to 26.59 μg/L， with an average value of 1.25 μg/L. The overall detection rate of chlorate was 30.71% （78/254）， and the detection value was not detected up to 927.66 μg/L， with an average value of 24.03 μg/L. The health risk of perchlorate and chlorate intake through milk powder was assessed as low for infants aged 0 to 36 months. Furthermore， the exposure of the high consumer population （P95） did not exceed the health guidance value.ConclusionThere is perchlorate and chlorate contamination in infant formula powder in Inner Mongolia. However， under the current pollution level， the health risk of perchlorate and chlorate ingestion through milk powder is low for infants under the age of 0-36 months. In addition， the exposure level of the high consumption group （P95） did not exceed the health guidance value， and the health risk was low. The exposure level of P95 in infants aged zero to six months is higher， and further attention should be paid to their health risks.

A method for simultaneous determination of chlorate and perchlorate amounts in meat by high performance liquid chromatography-tandem mass spectrometry was developed. Samples were extracted with acetonitrile/water (13:7, V:V ) and centrifuged. The obtained supernatants were purified on a PRiME HLB solid phase extraction column, followed by an Acclaim Trinity P1 ion exchange column with the gradient elution of acetonitrile and 20 mmol/L ammonium acetate as the mobile phase to afford chlorate and perchlorate. MS/MS was performed in ESI+ and multiple reaction monitoring mode with an internal standard for quantification. The results showed chlorate and perchlorate had calibration curves with good linearity in the ranges of 2~200.0 ng/mL and 1~100.0 ng/mL respectively, with corresponding correlation coefficients being 0.9983 and 0.9998. The detection limits of the method were 2.0 and 1.0 μg/kg, respectively. The recovery rates of chlorate and perchlorate were 91.0%~105.7% and 94.2%~110.5% respectively, at the addition levels of 6.0, 20, 40, 200 μg/kg, and 3.0, 10, 20, 100 μg/kg. The relative standard deviations for chlorate and perchlorate were 1.8%~9.7% and 0.7%~9.4% respectively. This method would be easy to use and has high detection sensitivity and good stability, and could well meet the requirements of determining chlorate and perchlorate amounts in meat.

ABSTRACTMicroorganisms are essential drivers of earth’s geochemical cycles. However, the significance of elemental redox cycling mediated by microorganisms is often underestimated beyond the most well-studied nutrient cycles. Phosphite, (per)chlorate, and iodate are each considered esoteric substrates metabolized by microorganisms. However, recent investigations have indicated that these metabolisms are widespread and ubiquitous, affirming a need to continue studying the underlying microbiology to understand their biogeochemical effects and their interface with each other and our biosphere. This review focuses on combining canonical techniques of culturing microorganisms with modern omic approaches to further our understanding of obscure metabolic pathways and elucidate their importance in global biogeochemical cycles. Using these approaches, marker genes of interest have already been identified for phosphite, (per)chlorate, and iodate using traditional microbial physiology and genetics. Subsequently, their presence was queried to reveal the distribution of metabolic pathways in the environment using publicly available databases. In conjunction with each other, computational and experimental techniques provide a more comprehensive understanding of the location of these microorganisms, their underlying biochemistry and genetics, and how they tie into our planet’s geochemical cycles.

This work focuses on the production, in continuous mode, of chlorate and hydrogen peroxide, using tailored electrochemical cells specially designed to obtain high efficiencies in these electrochemical processes. Then, these chlorate and hydrogen peroxide electrochemically produced were mixed for the chemical formation of chlorine dioxide, susceptible to be used for environmental applications. In this work, not only the prototype's conceptualization, design, and 3-D printing manufacturing are realized, but also the characterization of the cells in terms of fluid dynamics, mass transfer, and production of the target compounds is made. The chlorate prototype, with an electrode area of 78.5 cm2, produced up to 1200 mg h−1 of a chlorate solution with a purity of 50 %. The hydrogen peroxide prototype, with an electrode surface area of 10.9 cm2, produced up to 9 mg h−1 of hydrogen peroxide with a concentration of up to 70 mg L−1. The chlorine dioxide was produced continuously with these compounds (HClO 3 and H 2 O 2), operating at low H 2 O 2 /HClO 3 ratios and with a highly acidic supporting media. The oxidant was effectively transferred to a gaseous stream through air stripping. It was then introduced to solutions containing iodine or methomyl to confirm its ability to oxidize substances and to assess its potential use for environmental applications. These findings indicate that using Gaseous Oxidants Mediated Electrochemical Technology (GOMET) with chlorine dioxide is a viable solution for environmental remediation, offering promising prospects for future research on this topic. [Display omitted] • ClO 2 can be produced in continuous mode from electrogenerated HClO 3 & H 2 O 2. • Tailored conceptualization, design, and 3-D printing manufacturing of cells. • Coulombic efficiencies in the production of H 2 O 2 of 50 % and 30 % for HClO 3. • Gaseous chlorine dioxide successfully applied to oxidize iodine and methomyl. [ABSTRACT FROM AUTHOR]

This research investigates the biodegradation of perchlorate in the presence of the co-contaminants nitrate and chlorate using soluble and slow-release carbon sources. In addition, the impact of bio-augmentation and dilution, which results in lower total dissolved salts (TDS) and contaminant levels, is examined. Laboratory microcosms were conducted using actual groundwater and soils from a contaminated aquifer. The results revealed that both soluble and slow-release carbon sources support biodegradation of contaminants in the sequence nitrate > chlorate > perchlorate. Degradation rates, including and excluding lag times, revealed that the overall impact of the presence of co-contaminants depends on degradation kinetics and the relative concentrations of the contaminants. When the lag time caused by the presence of the co-contaminants is considered, the degradation rates for chlorate and perchlorate were two to three times slower. The results also show that dilution causes lower initial contaminant concentrations, and consequently, slower degradation rates, which is not desirable. On the other hand, the dilution resulting from the injection of amendments to support remediation promotes desirably lower salinity levels. However, the salinity associated with the presence of sulfate does not inhibit biodegradation. The naturally occurring bacteria were able to support the degradation of all contaminants. Bio-augmentation was effective only in diluted microcosms. Proteobacteria and Firmicutes were the dominant phyla identified in the microcosms. [ABSTRACT FROM AUTHOR]

In recent years, chlorate has become a residue of concern internationally, due to the risk that it poses to thyroid gland function. However, little is known about its occurrence in dairy products of Irish origin. To address this, a study was conducted in which samples of milk (n = 317), cream (n = 199), butter (n = 178), cheese (n = 144) and yoghurt (n = 440) were collected from grocery stores in the Republic of Ireland. Sampling was conducted across spring, summer, autumn and winter of 2021. Samples from multiple manufacturers of each respective dairy product were procured and analysed for chlorate using UPLC-MS/MS. Chlorate was detected in milk, cream, natural, blueberry, strawberry and raspberry yoghurts. Mean chlorate levels detected in these products were 0.0088, 0.0057, 0.055, 0.067, 0.077 and 0.095 mg kg−1, respectively. Chlorate was undetected in butter and cheese (<0.01 mg kg−1). All products sampled, except yoghurt, were found to be compliant with the EU limit for chlorate in milk (0.10 mg kg−1). Some manufacturers produced product with greater incidence and levels of chlorate. Chlorate levels from samples tested at different times of the year did not differ significantly, with the exception of strawberry and raspberry yoghurts which had higher chlorate levels in the winter period. [ABSTRACT FROM AUTHOR]

Firework displays are an integral part of festivals. Kerala is a host of innumerable firework displays. Perchlorate is used as an oxidizer in fireworks. Water samples and soil samples collected after firework display in selected sites of Kerala were analyzed using liquid chromatography–mass spectrometry (LC–MS). Both soil and water samples after the firework display were found to be contaminated with perchlorate. Average perchlorate in soil ranges from below detectable limits to 20451.14 ppb and in water from below detectable limits to 7.23 ppb. Perchlorate in soil was found to be maximum on the third day after the fireworks display. The present study gives an awareness of the perchlorate contamination resulting from the fireworks display in Kerala. [ABSTRACT FROM AUTHOR]

Platinum-plated niobium anodes are commonly used in the electrochemical oxidation of chlorate-containing solutions. In this research, a novel mechanism has been presented for the deactivation of Pt/Nb anodes in this process and the effect of the electrolyte temperature has been investigated in this mechanism. The samples were exposed to the accelerated life test (ALT) in the chlorate-containing electrolyte at temperatures of 35, 50, and 65 °C at a current density of 1200 mA cm−2 for 3, 10, 40, and 70 h. The electrochemical behavior of the samples was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods at each time interval. The morphology of the samples was also observed using scanning electron microscopy (SEM), before and after the ALT. The results showed that the highest corrosion resistance is obtained in the electrolyte with a temperature of 35 °C; the temperature at which the anode has the most increased electrocatalytic activity. However, at 65 °C, the anode is deactivated after 60 h of ALT, through the dissolution of platinum coating and subsequently the substrate passivation. Generally, passivation of niobium substrate is the progressive mechanism in the electrolyte at low temperatures, while, at high temperatures, deactivation starts from platinum coating dissolution and proceeds by substrate passivation. [ABSTRACT FROM AUTHOR]

Objectives The purpose of this study is to suggest operating conditions that can minimize the disinfection by-products of sodium hypochlorite produced in on-site sodium hypochlorite generators. Methods The characteristics of disinfection by-products were investigated by operating conditions (dissolved water type, brine concentration, temperature of electrolytic cell inflow water, pH of electrolytic cell inflow water and electrolyzer current density) using a on-site sodium hypochlorite generator(5 kg/day). Results and Discussion The concentration of disinfection by-products (chlorate, bromate) according to the type of dissolved water was found to be high in the order of softened water > tap water > RO treated water. As the brine concentration increased, chlorate decreased and bromate increased. The optimal saline concentration was found to be 3% or more. As temperature of electrolytic cell inflow water increases,, chlorate decreases and bromate increases. The difference in the concentration of disinfection by-products(chlorate, bromate) according to the pH of electrolytic cell inflow water is not large, and the appropriate pH is determined to be about 7 when the free available chlorine and disinfection by-products are taken into account. Also, as the current density increases, the chlorate increases and bromate showed a decreasing trend. Conclusion It has been shown that the concentration of disinfection by-products can be minimized when operating within the operating range suggested by the on-site sodium hypochlorite generator manufacturer, and some operating conditions are thought to have been suggested by the manufacturer to protect the electrolyzer cells. As the market for on-site sodium hypochorite generator gradually expands, it is expected that improved facilities will be continuously released in consideration of the stricter standards for disinfection by-products.

Objectives This study was conducted to suggest field operating conditions that can minimize disinfection by-products for three types of sodium hypochlorite. Methods In this study, changes in free available chlorine, chlorate and bromate were analyzed according to storage temperature, storage time and presence or absence of sunlight for three types of sodium hypochlorite(two types of bleach and one type of sodium hypochlorite made on-site hypochlorite generator). Results and Discussion In the case of bleach with 12% free available chlorine, when operating with a target of 10% of more of free available chlorine, the storage time for each storage temperature was 3 days at 40℃, 13 days at 30℃, 27 days at 20℃, 85 days at 10℃, and 200 days at 5℃. In the case of bleach with 5% free available chlorine, when operating with a target of 4% of more of free available chlorine, the storage time for each storage temperature was 37 days at 35℃, 255 days at 20℃, 1,343 days at 10℃, and 4,821 days at 4℃. In the case of sodium hypochlorite with 0.8% free available chlorine made on-site hypochlorite generator, when operating with a target of 0.7% of more of free available chlorine, the storage time for each storage temperature was 10 days at 3 5℃, 42 days at 20℃, 470 days at 10℃, and 1,770 days at 4°C. As a result of evaluating the quality change according to the presence or absence of UV protection, the free available chlorine decreased rapidly when exposed to sunlight, whereas the free available chlorine decreased slowly in the case of indoor storage. Conclusion Bleach with 12% free available chlorine can be stored for about 60 days at 15℃, and bleach with 5% free available chlorine can be used within about 6 months at 15℃. And sodium hypochlorite with 0.8% free available chlorine can be used within 10 days at room temperature. In addition, when storing sodium hypochlorite, it is suggested that it be stored indoors protected from sunlight.

Gold extraction by chloride is an important cyanide-free gold extraction process, which has been paid more and more attention because of its advantages of high leaching rate and no use of cyanide. Research on gold extraction by chlorination has shown a significant increase since 2010, and there are more literatures on gold extraction by liquid chlorination. Soon after the birth of the chlorination gold extraction process, the cyanidation method came out one after another. At that time, due to the relatively backward material industry, the corrosion problem faced by the chlorination method restricted its development, and was subsequently replaced by the cyanide method. Since 2000, material science has developed rapidly, and advanced corrosion-resistant materials have cleared the way for the chlorination process., moreover, with the development of human society, the ecological balance and environmental protection issues brought about by industrial production surpass the industrial development itself Therefore, chlorinated gold extraction process will be further developed.

The effect of three surface applied nitrate leaching mitigation treatments 3,4-dimethylpyrazole phosphate (DMPP), sodium chlorate (ClO3-) and a combination of Gibberellic acid and Lignosulphonate (GA + LS) at two levels (R1, R2) were compared to a single level of dicyandiamide (DCD, 10 kg ha−1) in lysimeter field sites in Canterbury and the Manawatu, New Zealand. All treatments were applied as surface sprays 24 h following urine application to simulate a practical application timing in a grazed pasture. In the Canterbury site, on a stony Lismore soil the treatments were ranked in order of significance (P < 0.1) and % reduction (as indicated in the brackets) in nitrate leaching from dairy urine patches (600 kgN ha−1): DCD (63%) >> DMPP (R2, 29%), GA + LS (R2, 25%), ClO3- (R1, 25%; R2, 23%) > DMPP (R1, 13%) >> GA + LS (R1, −18%), while in the Manawatu site with a volcanic pumice soil the rankings were: ClO3- (R1, 41%; R2, 37%), DMPP (R2, 32%) GA + LS (R2, 15%) > DMPP(R1, 18%) >> DCD (4%), GA + LS (R1, −3%). The results showed that the efficacy of GA + LS increased with application rates while the increase in rate for the chlorate (ClO3-) produced no further reductions in nitrate leaching. [ABSTRACT FROM AUTHOR]

Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of the lowering in the static ionic polarizability. In this paper, we present an experimental study that confirms the results of previous simulations. The lyotropic nature of aqueous solutions of sodium halates, i.e., NaClO3, NaBrO3, and NaIO3, is investigated through density, conductivity, viscosity, and refractive index measurements as a function of temperature and salt concentration. From the experimental data, we evaluate the activity coefficients and the salt polarizability and assess the anions' nature in terms of kosmotropicity/chaotropicity. The results clearly indicate that iodate behaves as a kosmotrope, while chlorate is a chaotrope, and bromate shows an intermediate nature. This experimental study confirms that, in the case of halates XO3−, the kosmotropic–chaotropic ranking reverses with respect to halides. We also discuss and revisit the role of the anion's polarizability in the interpretation of Hofmeister phenomena. [ABSTRACT FROM AUTHOR]

ObjectiveTo investigate chlorate contamination level in infant formula sold in Shanghai， and to evaluate the dietary exposure risk to infants in Shanghai.MethodsWith the risk monitoring data of chlorate in infant formula sold in Shanghai in 2020， combined with the dietary consumption data of infants， the dietary exposure of chlorate in infant formula was assessed via the point assessment method.ResultsIn 2020， the overall detection rate of chlorate in 120 infant formula samples was 98.3% （118/120）， the mean content was 124.5 μg⋅kg-1， the 50 percentile value was 64.6 μg⋅kg-1， and the maximum value was 1 475.0 μg⋅kg-1. The mean and 95 percentile value of daily chlorate intake from infant formula for infants aged 0‒36 months in Shanghai were 1.10 and 1.84 μg⋅kg-1， accounting for 36.7% and 61.3% of the tolerable daily intake （TDI） of chlorate （3μg⋅kg-1）， respectively. The mean， 50 percentile value and 95 percentile value of daily chlorate exposure of infants in different month-age groups （0‒6 months， 6‒12 months， 12‒36 months） through infant formula were lower than the TDI value.ConclusionThe health risk of daily chlorate intake from infant formula for infants and young children aged 0‒36 months in Shanghai is at an acceptable level.

[Display omitted] • 2-Nitro and 2,4-dinitro pyrroles can be achieved via a green acidic-free process. • Choline nitrate firstly served as a reagent for the photocatalytic nitration. • Photoinduced electrons and palladium NPs took pivotal roles during that. • Shifts of cyclic voltammetry uncovered photochemical transformation of nitrates. Escaping from conventional hazardous methods, an innovative, acidic-free approach for the synthesis of nitro-heterocycles was realized through photocatalytic nitration using Pd-doped g-C 3 N 4. In this method, chlorate nitrate was initially utilized as a reagent. Spectral analysis and electronic microscopy confirmed the successful doping of Pd nanoparticles (NPs) onto the g-C 3 N 4 surface, which subsequently enhanced the photocatalytic performance. The photogenerated electrons and Pd NPs played pivotal roles in the production of nitro-products. The reactive intermediate, NO2+, derived from nitrate, can be captured and elucidated through the shifts in cyclic voltammetry (CV) curves. Herein, the synthesis of 2-nitropyrrole and 2,5-dinitropyrrole was achieved through the nitration of chlorate nitrate in a friendly manner. Moreover, the composite photocatalyst could be readily isolated and recycled in next four tests, demonstrating its practicality and sustainability in photocatalytic applications. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that often encounters hypoxic/anoxic environments within the host, which increases its tolerance to many conventional antibiotics. Toward identifying novel treatments, we explored the therapeutic potential of chlorate, a pro‐drug that kills hypoxic/anoxic, antibiotic‐tolerant P. aeruginosa populations. While chlorate itself is relatively nontoxic, it is enzymatically reduced to the toxic oxidizing agent, chlorite, by hypoxically induced nitrate reductase. To better assess chlorate's therapeutic potential, we investigated mechanisms of chlorate toxicity and resistance in P. aeruginosa. We used transposon mutagenesis to identify genes that alter P. aeruginosa fitness during chlorate treatment, finding that methionine sulfoxide reductases (Msr), which repair oxidized methionine residues, support survival during chlorate stress. Chlorate treatment leads to proteome‐wide methionine oxidation, which is exacerbated in a ∆msrA∆msrB strain. In response to chlorate, P. aeruginosa upregulates proteins involved in a wide range of functions, including metabolism, DNA replication/repair, protein repair, transcription, and translation, and these newly synthesized proteins are particularly vulnerable to methionine oxidation. The addition of exogenous methionine partially rescues P. aeruginosa survival during chlorate treatment, suggesting that widespread methionine oxidation contributes to death. Finally, we found that mutations that decrease nitrate reductase activity are a common mechanism of chlorate resistance. [ABSTRACT FROM AUTHOR]

Chlorates and perchlorates are endocrine disruptors and emerging environmental contaminants found in various types of foods, including milk and dairy products. The presence of chlorate has been associated with the use of chlorine-based sanitizers to disinfect equipment and water used in food processing. Perchlorate, on the other hand, occurs naturally in the environment but is also released from anthropogenic sources. To protect consumers, the EU set an MRL for chlorate in milk but not for perchlorate. Considering that data on chlorates and perchlorates in this field are limited, the objective of this study was to assess the presence of these two anions in 148 samples of raw bovine milk collected from different farms of Lombardy and grouped in three different geographical zones. Chlorate was detected in 73% of the samples analyzed, at concentrations ranging from −1 with an average value of 7.10 ± 5.88 μg kg−1 below the MRL; perchlorate with a frequency of 99%, in the range from −1 and an average value of 4.06 ± 1.58 μg kg−1. No significant differences were detected among the three geographical zones. An evaluation of the estimated daily intake of perchlorate through milk confirmed the absence of risk for Italian consumers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In situ electrochlorination can offer an efficient and feasible solution to enable decentralized water disinfection. Unfortunately, there has been only a limited number of studies exploring single-pass flow cell systems with representative flowrates used at household level, particularly under varying chloride concentrations. This work aims to assess anode materials in a single pass and examine the impact of cross velocity, current density, and chloride concentration on various responses such as chlorine production and energy consumption. The primary objective is to determine whether the flow cell can achieve desirable chlorine levels under consistent operation while chloride content of water varies. Chlorine (Cl 2 /HOCl/OCl - ), chlorine dioxide (ClO 2 ) production, and toxic oxyanions (ClO 3 - , ClO 4 - ) were assessed in a single pass setup utilizing different representative anodes including Ti/RuO 2 , Ti/IrO 2 , and Boron-doped diamond. Among these materials, the Ti/RuO 2 anode emerged as the most suitable for effective chlorine generation while minimizing the formation of ClO 3 - and ClO 4 - . The performance of in situ electrochlorination using the Ti/RuO 2 anode in the flow cell revealed that cross velocity exerted the most significant influence on chlorine generation, while chloride content and current density primarily impacted energy consumption. Optimization of the operating parameters illustrated that stable chlorine concentrations ranging from 2 to 4 mg L -1 could be maintained even with significant fluctuations in chloride concentration from 50 to 250 mg L -1 , resulting in a daily energy consumption of less than 0.07 kWh per treated volume of 634 L (i.e., < 0.11 Wh L -1 ). These experimental findings hold promise for advancing electrodisinfection systems to higher technological readiness level., Competing Interests: Sergi Garcia-Segura is an Editor of the journal but was not involved in the peer review or handling of this paper., (© 2024 The Authors.)

Perchlorate and chlorate are recognized as ubiquitously inorganic pollutants inenvrionment owing to their high solubility in water and resistance to degradation. Previous studies have confirmed the potential adverse effects of perchlorate and chlorate on human thyroid function, along with implications for fetal growth and development. The fetus grows and develops pregnant women's womb and absorbs nutrients from her body. However, there is still limited information on prenatal exposure to perchlorate and chlorate and the related health risks, especially in China. In this study, a total of 430 serum specimens obtained from pregnant females residing in Southern China were analyzed to ascertain the levels of perchlorate and chlorate, and explore the relationship between perchlorate and chlorate and thyroid function by linear regression, WQS, and QGC. The measured serum levels of perchlorate and chlorate were comparatively elevated, demonstrating median values of 0.693 μg/L and 1.36 μg/L, respectively. The estimated exposure dose of perchlorate in 19.7% of pregnant women exceeded the USEPA reference dose, indicating potential health risks. Although no significant association was found between serum perchlorate and thyroid hormone levels, the exposure to perchlorate for pregnant women in Southern China is cause for concern given their sensitivity to chemicals during pregnancy and the relatively high internal exposure levels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Ion exchange chromatography-tandem mass spectrometry (IEC-MS/MS) has recently become the preferred method for detecting ionic substances in tea. In this study, an IEC-MS/MS method was developed for the rapid determination of chlorate and perchlorate residues in tea samples. The optimal sample extraction process, pretreatment column, and chromatographic and mass spectrometric conditions were systematically investigated. In the optimal process, the tea samples were ultrasonically extracted with methanol-water (13∶7, v/v), and a PRiME HLB SPE column was used to purify the sample extract. An AceChrom Hybri-A IEC column (150 mm×2.1 mm, 5.0 μm) was used for separation, and 100 mmol/L ammonium acetate-acetonitrile (40∶60, v/v) was used as the mobile phase for isocratic elution. The flow rate was 0.3 mL/min, the column temperature was 40 ℃, and the injection volume was 5.0 μL. The mass spectrometric data were collected in negative electrospray ionization mode combined with multiple reaction monitoring (MRM) mode to achieve the rapid and accurate separation and qualitative analysis of the desired chemical components. Quantification was performed using the internal standard (IS) method. The measurement results showed a good linear relationship when the mass concentrations of chlorate and perchlorate were between 2.00-200 and 1.00-100 μg/L, respectively, with correlation coefficients ( r ) greater than 0.9990. The average recoveries of chlorate and perchlorate at three spiked levels of low, medium, and high ranged from 88.54% to 97.25% with relative standard deviations (RSDs, 2 =7) of 3.2%-5.2%. The limits of detection for chlorate and perchlorate were 12.0 and 8.0 μg/kg, respectively, while the limits of quantification were 40.0 and 26.6 μg/kg, respectively. The results of tests conducted to assess the linearity, specificity, accuracy, precision, and applicability of the method to the analysis of chlorate and perchlorate in 15 tea samples collected from a local market demonstrated its validity for the routine analysis of tea samples. The proposed method is simple, rapid, sensitive, and accurate, and can meet requirements for the rapid screening and quantitative analysis of residual trace chlorate and perchlorate in large quantities of tea samples.n =7) of 3.2%-5.2%. The limits of detection for chlorate and perchlorate were 12.0 and 8.0 μg/kg, respectively, while the limits of quantification were 40.0 and 26.6 μg/kg, respectively. The results of tests conducted to assess the linearity, specificity, accuracy, precision, and applicability of the method to the analysis of chlorate and perchlorate in 15 tea samples collected from a local market demonstrated its validity for the routine analysis of tea samples. The proposed method is simple, rapid, sensitive, and accurate, and can meet requirements for the rapid screening and quantitative analysis of residual trace chlorate and perchlorate in large quantities of tea samples.

ObjectiveTo establish a method for the determination of chlorate and perchlorate in seasoning samples by ultra-performance liquid chromatography tandems mass spectrometry (UPLC-MS/MS).MethodsSeasoning sample was ultrasonically extracted with acidic acetonitrile solution, and then purified with a graphitized carbon black (GCB) cartridge and an Ag/H cartridge. UPLC-MS/MS analysis was conducted under multi-reaction monitoring mode with isotope-labelled internal standard calibration for quantification.ResultsChlorate and perchlorate showed a good linearity (R2≥0.99) in the range of 1-1 000 μg/L and 0.1-100 μg/L, respectively. The limits of detection for chlorate and perchlorate were 3.0 μg/kg and 0.3 μg/kg, as well as the limits of quantification were 10 μg/kg and 1.0 μg/kg, respectively. The average recoveries of two compounds in seasoning samples at three spiked levels were 86.5%-113.7% and the relative standard deviations were 1.8%-15.3%. The detection rates of chlorate and perchlorate from 122 seasoning samples were 76.2% and 93.4%, with the maximum concentration of 30.4 mg/kg and 12.3 mg/kg, respectively.ConclusionThe method is suitable for qualitative and quantitative analysis of chlorate and perchlorate in seasoning. Further study should be focused on the perchlorate in seasoning products since its relative prevalence contamination.

The aim of this study was to better evaluate the impact of on-site electro-generated hypochlorite for water disinfection. For this venture, the daily variability of hypochlorite-generating systems and their performance to produce low disinfection by-products during the formation of hypochlorite were observed. Seven on-site electro-generated hypochlorite installations, were selected at different swimming pool facilities in Switzerland. Active chlorine (AC), the two disinfection by-products chlorate (ClO3-) and perchlorate (ClO4-), and the pH were monitored over several hours. All monitored installations produced significant concentrations of chlorate, related to the measured active chlorine concentration. The median chlorate concentrations ranged between 1.4 to 76.9 µg ClO3-/mg AC during daily monitoring. Perchlorates have been detected only in the installations of one brand that generated concentrations up to 34.9 µg ClO4-/mg AC. For all installations, pH was lower than expected with a median pH of 9.6. Some samples presented even surprisingly acidic pH leading to possible sample degradation. This study clearly shows the weakness of a one-shot sampling to evaluate the quality of on-site electro-generated hypochlorite systems, due to high daily process variations. Additionally, the evaluation of the influence of three process parameters has pointed out that including chlorate aspects during the optimisation stage of on-site generated hypochlorite may significantly reduce chlorate contamination during water disinfection.

In recent years, chlorate has become a residue of concern internationally, due to the risk that it poses to thyroid gland function. However, little is known about its occurrence in dairy products of Irish origin. To address this, a study was conducted in which samples of milk (n = 317), cream (n = 199), butter (n = 178), cheese (n = 144) and yoghurt (n = 440) were collected from grocery stores in the Republic of Ireland. Sampling was conducted across spring, summer, autumn and winter of 2021. Samples from multiple manufacturers of each respective dairy product were procured and analysed for chlorate using UPLC-MS/MS. Chlorate was detected in milk, cream, natural, blueberry, strawberry and raspberry yoghurts. Mean chlorate levels detected in these products were 0.0088, 0.0057, 0.055, 0.067, 0.077 and 0.095 mg kg−1, respectively. Chlorate was undetected in butter and cheese (−1). All products sampled, except yoghurt, were found to be compliant with the EU limit for chlorate in milk (0.10 mg kg−1). Some manufacturers produced product with greater incidence and levels of chlorate. Chlorate levels from samples tested at different times of the year did not differ significantly, with the exception of strawberry and raspberry yoghurts which had higher chlorate levels in the winter period.

BACKGROUND: This work focuses on the electrochemical production of chlorate solutions for direct use and integration in the manufacture of chlorine dioxide (ClO2), from the perspective of manufacturing portable ClO2 electrochemical generators. RESULTS: Chlorate production was evaluated from the oxidation of sodium chloride (NaCl) contained in brackish solutions (20 g L−1) and brines (200 g L−1) in single chamber flow electrochemical cells. Efficiency in chlorate ion (ClO3−) production increased with temperature and NaCl concentration, but the use of brackish solutions led to a higher quality product, as compared to the brines, with lower concentration of chlorine and hypochlorous acid. To evaluate the production of ClO2, samples corresponding to two different qualities of the electrogenerated solutions underwent stripping to exhaust chlorine, before being mixed with hydrogen peroxide (H2O2) and sulfuric acid. Results showed that using a chlorate solution obtained from the electrolysis of 20 g L−1 NaCl solution at 50 mA cm−2 and passing 57.35 Ah L−1, a maximum concentration of 33.3 mmol L−1 ClO2 could be attained, which corresponds to a maximum conversion of 48.75%. CONCLUSIONS: Efficiency of the synthesis depends on both the purity of chlorate and the H2O2/ClO3− ratio. This confirms that in‐situ electrogenerated chlorate can be used to manufacture ClO2, but there are still many gaps to be overcome and further work must be carried out to optimize the production of the desired oxidant in a portable ClO2 device. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Single-crystal precursor of hybrid oxides NiO–MnCo2O4–Ni6MnO8 (SCNCM) is synthesized via an improved continuous two-step spray pyrolysis system (CTSP). This kind of mixed oxide is to be regarded as an ideal precursor for the single-crystal Ni-rich Li[Ni 0. 6 Co 0. 2 Mn 0. 2 ]O2 cathode materials (SCLNCM). The new pilot plant (30 t/a), method, and chlorate in this work could extremely improve the lengthy process, reducing segregation of metal element, excessive sintering temperature, high water consumption, non-polluting, and production efficiency of the SCLNCM. The resulting SCLNCM powders have a type of fine particle size and porous structure with a typical α -NaFeO2 lamellar structure. It also has a type of better cyclic stability, safety, rate capability, crystallinity, and surface area than polycrystalline cathode materials. It delivers an initial discharge capacity of 184 mAh/g at 0.1 C (18 mA/g) with a capacity retention of 91% after 100 cycles in the voltage window of 2.8–4.3 V. [ABSTRACT FROM AUTHOR]

Perchlorate is a widespread drinking water contaminant with regulatory standards ranging from 2 to 18 μg/L. The hydrogen-based membrane-biofilm reactor (MBfR) can effectively reduce perchlorate, but it is challenging to achieve low-µg/L levels. We explored chlorate addition to increase the abundance of perchlorate-reducing bacteria (PRB) and improve removals. MBfR reactors were operated with and without chlorate addition. Results show that chlorate doubled the abundance of putative PRB (e.g., Rhodocyclales) and improved perchlorate reduction to 23 ± 17 µg/L, compared to 53 ± 37 µg/L in the control. Sulfate reduction was substantially inhibited during chlorate addition, but quickly recovered once suspended. Our results suggest that chlorate addition can enhance perchlorate reduction by providing a selective pressure for PRB. It also decreases net sulfate reduction. Key points: • Chlorate increased the abundance of perchlorate-reducing bacteria • Chlorate addition improved perchlorate removal • Chlorate appeared to suppress sulfate reduction [ABSTRACT FROM AUTHOR]

While the microbial degradation of a chloroxyanion-based herbicide was first observed nearly ninety years ago, only recently have researchers elucidated the underlying mechanisms of perchlorate and chlorate [collectively, (per)chlorate] respiration. Although the obvious application of these metabolisms lies in the bioremediation and attenuation of (per)chlorate in contaminated environments, a diversity of alternative and innovative biotechnological applications has been proposed based on the unique metabolic abilities of dissimilatory (per)chlorate-reducing bacteria (DPRB). This is fueled in part by the unique ability of these organisms to generate molecular oxygen as a transient intermediate of the central pathway of (per)chlorate respiration. This ability, along with other novel aspects of the metabolism, have resulted in a wide and disparate range of potential biotechnological applications being proposed, including enzymatic perchlorate detection; gas gangrene therapy; enhanced xenobiotic bioremediation; oil reservoir bio-souring control; chemostat hygiene control; aeration enhancement in industrial bioreactors; and, biogenic oxygen production for planetary exploration. While previous reviews focus on the fundamental science of microbial (per)chlorate reduction (for example see Youngblut et al., 2016), here, we provide an overview of the emerging biotechnological applications of (per)chlorate respiration and the underlying organisms and enzymes to environmental and biotechnological industries.

Perchlorate, chlorate and bromate are ubiquitously present in the environment. Perchlorate and chlorate could affect thyroid functions, while bromate is carcinogenic and has been listed as a possible human carcinogen in group 2B by the International Agency for Research on Cancer (IARC). This study aimed to determine the occurrence of perchlorate, chlorate and bromate in three types of drinking water (n=226) in Shenzhen, and assess potential human exposure risks. The detection rates of chlorate and perchlorate were both greater than 60%, and they were positively correlated in both bottled water and tap water, indicating similar sources. Bromate and chlorate were negatively correlated in tap water, indicating that the production of them in tap water disinfection might restrict each other. The hazard quotient (HQ) and hazard index (HI) values of perchlorate, chlorate and bromate in drinking water were less than 1 regardless of age groups. However, for bromate some individual excess cancer risk (ICER) values in drinking water exceeded the maximum acceptable level, indicating potential cancer risk to Shenzhen residents.

Perchlorate and chlorate are chemically stable species with high solubility and are widely distributed in various foods. Dietary intake is considered to be the main route of human exposure to these chemicals. Aquatic products are an important component of residents' daily diets. However, there is still a lack of a complete research report on perchlorate and chlorate contamination in aquatic products. Thus, this study investigated the concentration of perchlorate and chlorate in shellfish, freshwater fish, freshwater shrimp, sea fish, and sea shrimp from Shenzhen and assessed human exposure risks. The detection frequency of chlorate was low, and the incidence of perchlorate was significantly lower than previous studies, demonstrating a substantial reduction in perchlorate contamination in Shenzhen waters. However, certain samples exhibited relatively elevated concentrations. The highest concentration of chlorate (43.1 µg kg−1) and perchlorate (14,865 µg kg−1) were both found in sea shrimp. Notably, the 95th percentile estimated daily intake (EDI) value of perchlorate derived from sea shrimp and shellfish surpassed the reference dose (R f D), while the EDI values of chlorate were all below the R f D. Therefore, Shenzhen residents are advised to consume sea shrimp and shellfish with caution to minimize the possible health risks linked to perchlorate and chlorate exposure. [Display omitted] • Perchlorate was frequently detected in aquatic products. • The highest level of perchlorate and chlorate were both detected in sea shrimp. • The risk of perchlorate via shellfish and sea shrimp consumption was relatively high. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As chlorate concentrations have been found to be harmful to human and animal health, governments are increasingly demanding strict control of the chlorate concentration in drinking water. Since there are no chlorate sensors available, the current solution is sampling and laboratory analysis. This is costly and time consuming. The aim of this work was to investigate Sensor Data Fusion (SDF) as an alternative approach, with a focus on chlorate formation in the electrochlorination process, and design an observer for the real-time estimation of chlorate. The pH, temperature and UV-a absorption were measured in real time. A reduced-order nonlinear model was derived, and it was found to be detectable. An Extended Kalman Filter (EKF), based on this model, was then used to estimate the chlorate formation. The EKF algorithm was verified experimentally and was found to be capable of accurately estimating chlorate concentrations in real time. Electrochlorination is an emerging and efficient method of disinfecting drinking water. Soft sensing of chlorate concentrations, as proposed in this paper, may help to better control and manage the process of electrochlorination. [ABSTRACT FROM AUTHOR]

Breakpoint chlorination (BC) and disinfection with chlorine-based disinfectant are widely used procedures in drinking water production. Both involve dosing chlorine into the raw water, where it can react with organic compounds, forming disinfection by-products (DBPs) of health concern. However, technological parameters (e.g., contact time, chlorine dosage, and bromide to residual free chlorine ratio) of the two chlorination procedures are different, which can lead to differences in DBP formation. To better understand this, a year-long sampling campaign was carried out at three waterworks in Hungary, where both BC and chlorine disinfection are used. To confirm the results of the field sampling, bench-scale experiments were carried out, investigating the impact of (a) bromide concentration in raw water, (b) residual free chlorine (bromide to residual chlorine ratio), and (c) contact time on DBP formation. The measured DBPs were trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and chlorate. During BC, the DBPs were formed in higher concentration, with the exception of one waterwork having elevated bromide content in the raw water. Bromine substitution factors (BSFs) were significantly higher during disinfection than BC in both field and laboratory experiments. After BC, the chlorate concentration range was 0.15–1.1 mg/L, and 96% of the samples exceeded the European Union (EU) parametric value (0.25 mg/L), whereas disinfection contributed only slightly. Granular activated carbon (GAC) filters used to remove DBPs in waterworks were exhausted after 6–8 months of use, first for those chlorinated THMs, which are generated predominantly during BC. The biological activity of the filters started to increase after 3–6 months of operation. This activity helps to remove the biodegradable compounds, such as disubstituted haloacetic acid (DHAAs) and HANs, even if the adsorption capacity of the GAC filters are low. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)