Search

Recent studies have implemented a calculated additive toxicity (CAT) approach that sums measured disinfection byproduct (DBP) concentrations weighted by their respective in vitro bioassay potencies to estimate their associated risk in disinfected waters. In this study, the CAT approach was used to systematically investigate 21 regulated and unregulated DBPs measured in drinking water at the household level. Water samples from the tap were collected from over 120 randomly selected participants supplied by eight public water systems using four distinct source water types, two types of disinfection processes, and across two seasons. The purpose of this study was to compare CAT using multiple biological end points, examine household variability, identify DBPs driving toxicity, and assess if current regulated DBPs are adequate predictors of unregulated DBPs. Our results support the significance of unregulated DBPs, particularly haloacetonitriles and iodoacetic acid, as drivers of toxicity. Simple linear models between regulated versus unregulated concentrations and CAT were overall weak with 67% considered poor (r 2 < 0.3). These results reveal that current regulatory monitoring approaches may not be adequately capturing true household exposure due to higher contribution of unregulated DBPs to CAT and poor predictability between regulated and unregulated DBP-mediated CAT.

Seawater chlorination has three main industrial uses: disinfection of water and installations, control of biofouling, and preventing the transport of aquatic invasive species. Once in contact with seawater, chlorine reacts rapidly with water constituents (e.g. bromide ions, ammonia, and nitrogen-containing compounds) to form a range of oxidative species (e.g. bromine and N-haloamines), termed "chlorine-produced oxidants" (CPOs) or "total residual oxidants" (TRO). The chemical nature of CPOs and their concentration are a function of two categories of parameters related to treatment modality (e.g. chlorine dose) and water quality (e.g. temperature, pH, ammonia concentration, and organic constituents). The chlorination process may result in continuous or intermittent releases of CPOs in seawater. The reactivity and potential ecotoxicity of CPO species largely depend on their physical and chemical properties. Therefore, evaluation of the biocidal effectiveness of chlorination and its potential impacts requires not only determining the sum of CPOs (via a bulk parameter), but also their chemical speciation. The aim of this article – which is the first of a trilogy dedicated to the chemical speciation of CPOs in seawater – is to provide an overview of current knowledge about chlorine chemistry in seawater and to discuss the biocidal efficacy and the environmental fate of resulting CPOs. The 2nd and 3rd articles delineate a comprehensive and critical review of analytical methods and approaches for the determination of CPOs in seawater. [ABSTRACT FROM AUTHOR]

Chlorination of seawater forms a range of secondary oxidative species, collectively termed "chlorine-produced oxidants" (CPOs). These compounds do not have the same biocidal efficacy, the same fate and behavior in the marine environment, the same potential formation of chlorination by-products (CBPs), nor the same effects on marine organisms. Their chemical speciation is an important step toward an accurate assessment of the effectiveness of chlorination and the potential impacts of its releases, among others. The aim of this paper - which is the second of a trilogy dedicated to the chemical speciation of CPOs in seawater - is to cover all aspects related to CPOs analysis in seawater, from sampling to instrumental determination. First, it discusses the procedures involved in synthesis, storage, and standardization of analytical standards. Second, it deals with sampling and sample preparation, addressing all relevant issues related to these two key steps. Third, it provides a comprehensive and up-to-date overview of the colorimetric, titrimetric, and electrochemical methods used for CPOs determination and thoroughly discusses their advantages and limitations. Finally, this review ends with some recommendations for progress in the field of CPO analysis with the three aforementioned approaches. Chromatographic and mass spectrometric-based methods will be covered in the third and final article (Part III). [ABSTRACT FROM AUTHOR]

The issue of the qualitative and quantitative analysis of the concentration of oxidising species in aquatic environments is crucial for a wide range of biological and environmental tasks. In particular, reactive chlorine species, specifically hypochlorite (ClO−), play a significant biochemical role in the operation of the immune system. There is also the challenge of determining the presence of ClO− in purified drinking water that is supplied by water treatment systems. Traditional chemical analytical methods often lack the required selectivity and sensitivity to detect oxidising compounds, and chemiluminescence-based techniques offer an alternative solution. In this study, we propose a simple and selective approach for the chemiluminescent detection of hypochlorite in aqueous media under neutral conditions. The technique is based on measuring a chemiluminescent signal generated in the presence of hypochlorite by a combined probe comprising commercially available WS2 quantum dots and luminol. The oxidation of WS2 with hypochlorite followed by a reaction with luminol results in an intense luminescent signal that enables the selective determination of hypochlorite under neutral conditions. The greatest sensitivity with this method was achieved when combining WS2 quantum dots with L-012, a highly sensitive analogue of luminol. Additionally, the use of L-012 improved the detection limit for hypochlorite to 2 × 10−6 M. Due to its selectivity in determining hypochlorite in the presence of reactive oxygen species (hydrogen peroxide) under neutral conditions with high sensitivity and with a wide linear range, the proposed approach provides an attractive analytical tool for the analysis of water samples and biological liquids. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

Macrocycle‐based host–guest complexation offers an intriguing protocol in producing chiroptical materials, while the bulky size and dynamic exchange between hosts and guests hinders the ordered aggregation to afford the long‐range chiral arrangement. It remains great challenges in assembling cucurbit[n]urils (CB[n]s) included complexes to induce supramolecular chirality ascribed to the excellent water solubility and flexible packing. Herein, we unveiled the structural basis on the formation of chiroptical coassemblies from CB[n] (n=6, 7) complexes. Perylene diimides (PDIs) with cationic chiral pendants formed complexes in the aqueous media, which selectively showed chiroptical properties. Chlorination at the bay position, increasing alkyl length of cationic chiral pendants or reducing the number of polyaromatic rings would hinder the chiral aggregation. In a comprehensive manner, CB[6] favors ordered aggregation into one‐dimensional fibrous nanoarchitectures that greatly facilitates the supramolecular chirality. In contrast, CB[7] with larger cavity and water solubility shrinks the ordered arrangement of complexes, reducing the formation possibility of supramolecular chiral nanoarchitectures. This work suggests the great potential of CB[6] in the preparation and manipulation of supramolecular chiral assemblies, shedding light on the macrocycle‐based functional chiroptical materials. [ABSTRACT FROM AUTHOR]

This article discusses how the notion of "diffusionism" has functioned as a straw man in the history of technology. This has prevented it from becoming fully global and symmetrical. In contrast the second section of this article offers an example of what a symmetrical account of the global history of technology might look like using the case of chlorination in the early twentieth century. Focusing on London Bogotá and Jersey City it shows that chlorination was initially rejected in each of these places but was later adopted in all of them for economic reasons after discussions that took the same form. It concludes by suggesting that global histories of technology must treat North and South East and West center and periphery and metropole and colony symmetrically drawing out similarities and differences based on the available evidence without assuming them in advance. [ABSTRACT FROM AUTHOR]

• Ozonation enhanced the formation potential of regulated DBPs from Phe chlorination. • CH with highest yield of 21.31+1.05 ug/mgPhe was enhanced to 3 times after ozonation. • The DBPs formation rates in the first 6 h were much higher than subsequent time. • Br− promoted brominated DBPs generation and elevated the total cytotoxicity. • Ozonation enhanced the BIF of THMs, while reduced that of DHAAs. As a strong oxidizing agent, ozone is used in some water treatment facilities for disinfection, taste and odor control, and removal of organic micropollutants. Phenylalanine (Phe) was used as the target amino acid to comprehensively investigate variability of disinfection byproducts (DBPs) formation during chlorine disinfection and residual chlorine conditions subsequent to ozonation. The results showed that subsequent to ozonation, the typical regulated and unregulated DBPs formation potential (DBPsFP), including trichloromethane (TCM), dichloroacetonitrile (DCAN), chloral hydrate (CH), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), and trichloroacetamide (TCAcAm) increased substantially, by 2.4, 3.3, 5.6, 1.2, 2.5, and 6.0 times, respectively, compared with only chlorination. Ozonation also significantly increased the DBPs yield under a 2 day simulated residual chlorine condition that mimicked the water distribution system. DBPs formations followed pseudo first order kinetics. The formation rates of DBPs in the first 6 hr were higher for TCM (0.214 hr−1), DCAN (0.244 hr−1), CH (0.105 hr−1), TCAcAm (0.234 hr−1), DCAA (0.375 hr−1) and TCAA (0.190 hr−1) than thereafter. The peak DBPsFP of TCM, DCAN, CH, TCAcAm, DCAA, and TCAA were obtained when that ozonation time was set at 5–15 min. Ozonation times > 30 min increased the mineralization of Phe and decreased the formation of DBPs upon chlorination. Increasing bromine ion (Br−) concentration increased production of bromine- DBPs and decreased chlorine-DBPs formation by 59.3%–92.2%. Higher ozone dosages and slight alkaline favored to reduce DBP formation and cytotoxicity. The ozonation conditions should be optimized for all application purposes including DBPs reduction. [Display omitted] [ABSTRACT FROM AUTHOR]

Umbria is an Italian region characterized by a highly fragmented water supply and distribution system, with many small systems fed by local sources. Chlorination in these small systems faces several challenges, including strong fluctuating demand, low economic significance, and limited access to infrastructure. Due to Italian regulations, the resulting frequent noncompliance with water quality standards negatively impacts performance indicators and tariffs. This research explores the possibility of implementing a low-cost chlorination system designed to adapt to varying environmental conditions (e.g., water and environmental temperature fluctuations, changes in pH, etc.) and demands. A prototype of the device was developed and tested in the Water Engineering Laboratory of the University of Perugia, Italy, to assess its ability to apply a programmable chlorination model. The effects of electronic environmental noise, along with the reliability of water meters, thermometer measurements, dosing pump control, local logging, and remote data transmission, were tested under different conditions. The results demonstrated the instrument's readiness for field applications in pilot studies under real-world conditions. [ABSTRACT FROM AUTHOR]

Electric arc furnace (EAF) dust is an important secondary resource containing metals, such as zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduce environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this issue, a facile approach that involves oxygen-assisted chlorination using molten MgCl2 is proposed. This work focused on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively broke down the ZnFe2O4 structure, and the high O2 atmosphere considerably promoted the separation of Zn from other components in the form of ZnCl2. The presence of O2 facilitated the formation of MgFe2O4, which stabilized Fe and prevented its chlorination. Furthermore, the excessive use of MgCl2 resulted in increased evaporation loss, and high temperatures promoted the rapid separation of Zn. Building on these findings, we successfully extracted ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination. Under optimized conditions, this method achieved exceptional Zn chlorination percentage of over 97% within a short period, while Fe chlorination remained below 1%. The resulting volatiles contained 85wt% of ZnCl2, which can be further processed to produce metallic Zn. The findings offer guidance for the selective recovery of valuable metals, particularly from solid wastes such as EAF dust. [ABSTRACT FROM AUTHOR]

This study discussed the effect of ferric salt addition on UV/electro-chlorine advanced oxidation process using a train of electrolytic and UV flow cells with an ozone-free low-pressure mercury vapour lamp (total irradiance:0.60 W at 254 nm). Ferric salt addition enhanced 1,4-dioxane degradation at an electrolytic current of 0.100 A. By contrast, an inhibitory effect of ferric salt addition was observed at a current of 0.500 A. The enhanced accumulation of free chlorine at a current of 0.500 A directly decreased the 1,4-dioxane degradation rate by scavenging reactive radicals like HO˙ and Cl˙. However, at an electrolytic current of 0.100 A, UV irradiance was relatively excessive for electrochemical chlorine production. The excess UV energy enhanced the photoreduction of FeOH2+, followed by the Fenton-type reaction of Fe2+ and HOCl, which produced HO˙ and consumed free chlorine. As a result, the free chlorine concentration decreased, and the reaction efficiency between the reactive radicals and 1,4-dioxane improved. Thus, the addition of ferric salt to a UV/electro-chlorine system is recommended when the UV irradiance in the system is excessive compared to the electrochemical chlorine supply. [ABSTRACT FROM AUTHOR]

Halogen-containing bridged carborane–tetraphenylethene compounds have been synthesized by the chlorination of the corresponding tetraphenylethene–carboranylmethanol. The fluorinated compound 1 shows interesting excitation-dependent emission (ex-de) properties in various aggregate states, i.e. powder before and after grinding, ground-fuming and ground-annealing, whereas the non-fluorinated analog compound 2 displays ex-de properties only after grinding. The carborane cluster, bridging group and halogen atoms cooperatively tune the emission properties of these compounds. Compound 1 has good crystallinity and multiple interactions in the molecular packing, thus in various aggregate states a mixture of crystalline and amorphous particles in an uncertain ratio renders the samples the corresponding ex-de properties, and compound 2 shows ex-de properties due to a similar reason. Compounds 1 and 2 exhibit typical aggregation-induced emission properties as they have tetraphenylethene moieties, and good photoluminescence quantum yields in the solid state (0.54, 1; 0.39, 2) being relatively high when compared to those of the reported carborane derivatives with ex-de properties. In addition, compound 1 shows a relatively wide-range emission wavelength shift (maximum 73 nm) at various excitation wavelengths. These results suggest a new convenient approach to synthesize various compounds with ex-de properties. [ABSTRACT FROM AUTHOR]

Following the Hunga Tonga–Hunga Ha'apai (HTHH) eruption in January 2022, significant reductions in stratospheric hydrochloric acid (HCl) were observed in the Southern Hemisphere mid‐latitudes during the latter half of 2022, suggesting potential chlorine activation. The objective of this study is to comprehensively understand the loss of HCl in the aftermath of HTHH. Satellite measurements and a global chemistry‐climate model are employed for the analysis. We find strong agreement of 2022 anomalies between the modeled and the measured data. The observed tracer‐tracer relations between nitrous oxide (N2O) and HCl indicate a significant role of chemical processing in the observed HCl reduction, especially during the austral winter of 2022. Further examining the roles of chlorine gas‐phase and heterogeneous chemistry, we find that heterogeneous chemistry emerges as the primary driver for the chemical loss of HCl, and the reaction between hypobromous acid (HOBr) and HCl on sulfate aerosols is the dominant loss process. Plain Language Summary: After the eruption of the Hunga Tonga–Hunga Ha'apai (HTHH) volcano in January 2022, there was a substantial decrease in stratospheric hydrochloric acid (HCl) in the Southern Hemisphere mid‐latitudes in the latter part of 2022. This decrease suggests that a chemical reaction involving chlorine processing might have happened. This study aims to comprehensively understand the significant loss of HCl following the HTHH eruption, utilizing satellite measurements and a global chemistry‐climate model for analysis. The anomalies in 2022 show remarkable agreement between the modeled and measured data. By comparing the levels of HCl with another gas called nitrous oxide (N2O), we discover that a lot of the HCl loss was due to chemical reactions, especially during the Southern Hemisphere winter. Upon further investigation into the role of chlorine gas‐phase and heterogeneous chemistry, heterogeneous chemistry emerges as a primary driver for the chemical loss of HCl. The reaction between hypobromous acid (HOBr) and HCl on sulfate aerosols is identified as the dominant loss process. Key Points: Analysis using both model and satellites suggest a significant role of chemical processing in the observed HCl reduction at 20 kmAnalysis of gas‐ and heterogeneous‐phase reactions indicates that heterogeneous chemistry is the main driver for the chemical loss of HClThe dominant heterogeneous loss for HCl is via HOBr + HCl, with HCl + OH also significant due to enhanced OH from heterogeneous chemistry [ABSTRACT FROM AUTHOR]

• CaCl 2 is an additive suitable for pyrometallurgical recovery of spent LIBs. • CaCl 2 has good chlorination ability and slag optimization ability. • SiO 2 and CO 2 in the system contribute to the increase in HCl yield. The difficulty of separating Li during pyrometallurgical smelting of spent lithium-ion batteries (LIBs) has limited the development of pyrometallurgical processes. Chlorination enables the conversion of Li from spent LIBs to the gas phase during the smelting process. In this paper, the effects of four solid chlorinating agents (KCl, NaCl, CaCl 2 and MgCl 2) on Li volatilization and metal (Co, Cu, Ni and Fe) recovery were investigated. The four solid chlorinating agents were systematically compared in terms of the direct chlorination capacities, indirect chlorination capacities, alloy physical losses and chemical losses in the slag. CaCl 2 was better suited for use as a solid chlorinating agent to promote Li volatilization due to its excellent results in these indexes. The temperature required for the release of HCl from MgCl 2 , facilitated by CO 2 and SiO 2 , was lower than 500 °C. The prematurely released HCl failed to participate in the chlorination reaction. This resulted in approximately 12 % less Li volatilization when MgCl 2 was used as a chlorinating agent compared to when CaCl 2 was used. In addition, the use of KCl as a chlorinating agent decreased the chemical dissolution loss of alloys in the slag. The performance of NaCl was mediocre. Finally, based on evaluations of the four indexes, recommendations for the selection and optimization of solid chlorinating agents were provided. [ABSTRACT FROM AUTHOR]

Growing concerns over public health and environmental safety have intensified the focus on minimizing harmful disinfection byproducts (DBPs) in water treatment. Traditional methods like chlorination, while effective against pathogens, often lead to the formation of DBPs, which pose significant risks. This paper explores alternative strategies to reducing DBP formation while ensuring effective disinfection. The methodology involved a bibliographic study conducted through the Scopus platform, using appropriate keywords. The initial search yielded 9576 articles from the period 2020 to 2024. The key approaches identified include advanced oxidation processes (AOPs) such as UV/H2O2 and ozone, which mineralize natural organic matter (NOM) and minimize chemical use and sludge production; membrane-based filtration systems, like reverse osmosis, effectively removing contaminants without chemical disinfectants, reducing DBP risks. Furthermore, conventional processes, such as coagulation and filtration, serve as crucial pretreatment steps to lower NOM levels before disinfection. Additionally, optimizing chlorine dosing, using non-chlorine disinfectants, and employing post-disinfection methods like adsorption and biological filtration further mitigate DBP formation. Finally, the integration of artificial intelligence in process optimization is emerging as a promising tool for enhancing treatment efficiency and safety. This research contributes to the development of safer, more sustainable water treatment solutions, addressing regulatory demands and public health objectives. [ABSTRACT FROM AUTHOR]

Halogenation is one of the most important transformations in organic synthesis. Halogenated compounds are employed in many reactions to prepare useful molecules. Many methods have been developed to introduce halogens into different compounds. Visible light‐mediated reactions are the efficient, low‐toxic, and mild‐condition methods applied for various organic chemistry transformations. Remarkably, there has been an increasing development in the application of visible light‐induced halogenation in recent years. Herein, we present a comprehensive summary of halogenation reactions including chlorination, bromination, and iodination under visible light irradiation since 2020. [ABSTRACT FROM AUTHOR]

Household water treatment (HWT) is recommended when safe drinking water is limited. To understand determinants of HWT adoption, we conducted a cross-sectional survey with 650 households across different regions in Haiti. Data were collected on 71 demographic and psychosocial factors and 2 outcomes (self-reported and confirmed HWT use). Data were transformed into 169 possible determinants of adoption across nine categories. We assessed determinants using logistic regression and, as machine learning methods are increasingly used, random forest analyses. Overall, 376 (58%) respondents self-reported treating or purchasing water, and 123 (19%) respondents had residual chlorine in stored household water. Both logistic regression and machine learning analyses had high accuracy (area under the receiver operating characteristic curve (AUC): 0.77–0.82), and the strongest determinants in models were in the demographics and socioeconomics, risk belief, and WASH practice categories. Determinants that can be influenced inform HWT promotion in Haiti. It is recommended to increase access to HWT products, provide cash and education on water treatment to emergency-impacted populations, and focus future surveys on known determinants of adoption. We found both regression and machine learning methods need informed, thoughtful, and trained analysts to ensure meaningful results and discuss the benefits/drawbacks of analysis methods herein. [ABSTRACT FROM AUTHOR]

Surface water pollution by industrial wastewater is one of the serious environmental problems of the Republic of Uzbekistan. A significant source of pollution is the textile industry, whose wastewater contains organic dyes and various related substances. This article presents the results of a study of the photooxidation of the active dye Red SPD after electrochemical degradation in an electrolytic cell with insoluble anodes. Studies have been carried out to determine the efficiency of active chlorine synthesis in the process of electrolysis of chloride solutions, the effect of active chlorine concentration, electrolyte composition, power consumption when using the combined electrochemical/ultraviolet irradiation process, and changes in the spectral characteristics of the dye solution for carrying out the photooxidation process have been studied. The technological parameters of the method of photooxidative post-treatment in treated water after electrochemistry are established, considering the concentration of oxidizing agents. The maximum current output of active chlorine occurs at a treatment time of 10 minutes. The use of NaCl as an electrolyte in comparison with Na2SO4 showed the best result in the purification process. When using NaCl with a concentration of 1.625 g L-1 in the composition of a sulfate-containing electrolyte, it can reduce the concentration of Red SPD to 1.0 mg L-1. Photooxidative degradation can become an alternative for post-treatment of wastewater from textile enterprises. The developed technology confirms the efficiency of using the combined cleaning method. [ABSTRACT FROM AUTHOR]

The chlorination of oxides of major concern in cassiterite concentrate with various chlorinating agents is investigated in light of their thermodynamic feasibilities to extract and recover their valuable metal components. Mechanisms responsible for the processes and their Gibbs free energy changes as a function of temperature to selectively separate and/or recover the metal(s) of interest and unwanted ones as their metallic chlorides are identified. Attention is given to gaseous (Cl2 and Cl2 + CO mixture) and solid (CaCl2 and MgCl2) chlorine sources, from which Cl2 + CO shows no reaction selectivity for any of the oxides but a feasible metal chloride formation for all. Chlorine gas (Cl2), on the other hand, could selectively form chlorides with metals of +2 oxidation state in their oxides, leaving those of high oxidation state unreacted. MgCl2, unlike CaCl2, is found capable of producing calcium, ferrous, and stannic chloride from their metallic oxides with enhanced reaction tendencies in the presence of silicon dioxide (SiO2). An overall study of the thermodynamic feasibility of all chlorine sources looked at alongside operational and environmental viabilities suitably suggests MgCl2 for a selective extraction of the valuable metal components in a cassiterite concentrate, in which case, moderate temperatures seem promising. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing 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.)

Reactive oxygen species (ROS) and reactive chlorine species (RCS) and their involvement in the degradation process are explored in this work by thorough kinetic modeling of the solar-activated hypochlorite degradation of Rhodamine B (RhB) dye. The kinetic modeling enabled the determination of rate constants for both radical and non-radical pathways of hypochlorite and the oxidation of RhB by free radicals. Using COPASI® software, fed with a kinetics mechanism of 144 chemical reactions, the free radical kinetic model accurately fitted experimental data under various conditions, including temperatures ranging from 25 to 55 °C and initial hypochlorite concentrations from 300 to 1000 µM, at a controlled pH of 11. Results indicate that increasing hypochlorite dosages and temperatures enhance free radical concentrations and RhB degradation rates. •OH and ClO• radicals were quantified as primary contributors to RhB degradation, while ozone played a minor role. The model provides profiles for ROS and RCS, details on radicals distribution in RhB degradation, and predictions of rate constants for the photolysis of ClO−: kR1 = 2.67 × 10−4 s−1 for the radical pathway (ClO−  → h ν O•− + Cl•), and kR2 = 1.88 × 10−5 s−1 and kR3 = 0 s−1 for the non-radical pathway (i.e., ClO−  → h ν O(3P) + Cl− and ClO−  → h ν O(1D) + Cl−, respectively). The rate constants for RhB reactions with O•−, Cl•, Cl2•− and ClO• were predicted to be 4.8 × 109 M−1 s−1, 1.45 × 109 M−1 s−1, 2.5 × 107 M−1 s−1 and 8.7 × 104 M−1 s−1, respectively. Lower rate constants were predicted for RhB reactions with HOCl•−, HO2•, O2•−, and O(3P), with values of 4.1 × 104 M−1 s−1, 7.3 × 105 M−1 s−1, 3.6 × 104 M−1 s−1, and 0.40 M−1 s−1, respectively. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, most sewage treatment plants increased disinfectant dosages to inactivate pathogenic viruses and microorganisms more effectively. However, this approach also led to the production of more disinfection by-products (DBPs). To ensure both disinfection efficiency and a reduction in DBP formation, new disinfection protocols are required. In this study, the disinfection efficiency, DBP amounts, and toxicity changes resulting from ozone (O3), ultraviolet (UV), chlorine (Cl2), and their combined processes were examined. The results demonstrated that the O3/UV/Cl2 combination achieved the highest disinfection efficiency. Chlorination produced the most DBPs, whereas UV treatment reduced the formation of trihalomethane (THM), halogenated ketones (HKs), haloacetic acids (HAA), dichloroacetonitrile (DCAN) and N-nitrosodimethylamine (NDMA) by 45.9%, 52.6%, 82.0%, 67.95%, and 47%, respectively. O3 also significantly reduced their production by 99.1%, 91.1%, 99.5%, 100%, and 35%. Intracellular organic matter (IOM) was identified as the primary DBP precursors, producing 2.94 times more DBPs than extracellular organic matter (EOM). The increased DBP formation during chlorination was attributed to IOM leakage and cell membrane damage, which was verified using scanning electron microscopy (SEM). The toxicities of DBPs were evaluated for six disinfection methods, revealing inconsistent results. The overall toxicities were assessed using zebrafish embryo experiments. Both evaluations indicated that chlorination alone was the least favorable method. In addition, the toxicities followed a sequence: Cl2 ≈ O3/Cl2 > O3 > O3/UV/Cl2 > UV > UV/Cl2. These findings can serve as a reference for sewage treatment plants in selecting appropriate disinfection methods to manage the COVID-19 epidemic from comprehensive perspective. [ABSTRACT FROM AUTHOR]

2,3-Diamino-5,6-dichloropyrazine represents a valuable but underexplored heterocyclic building block. Due to the use of harsh conditions and lack of selectivity surrounding the known literature synthesis, we developed a more accessible and selective three-step route from 2-aminopyrazine. Challenging conditions are avoided by using a high-yielding dichlorination with N -chlorosuccinimide (NCS), which is followed by a regioselective amination. The installation of the last chlorine atom using 1-chloro-1,2-benziodoxol-3(1 H)-one is rapid, enabling access to 2,3-diamino-5,6-dichloropyrazine in an improved overall yield (41%). [ABSTRACT FROM AUTHOR]

Chlorination of seawater forms a range of secondary oxidative species – collectively called "chlorine-produced oxidants" (CPOs) – having different biocidal, environmental and ecotoxicological properties. The chemical speciation of these compounds is an important step in attempts to assess the effectiveness of chlorination and the potential impacts of its releases. However, comprehensive determination of CPOs represents a significant analytical challenge for many reasons, including the following: CPO species are numerous, highly reactive, with short-lifetimes, difficult to isolate and generally present at low concentrations in a complex salt matrix. Literature review reveals the development of a wide variety of analytical approaches for analysis of CPOs, either collectively via group parameters or individually. A first category of these approaches was the subject of article II (also including sampling and sample preparation) of a trilogy devoted to the chemical speciation of CPOs in seawater. In this third article – which closes the trilogy – emphasis is placed on chromatographic- and mass spectrometric-based approaches. It reviews more than 80 methods, reported from 1981 to date, and thoroughly discusses their principles and performances. Methodologies involving chemical derivatization of CPOs prior to their analysis by gas or liquid chromatography coupled to mass spectrometry provide the best sensitivities, achieving sub-ppb detection limits for species for which suitable derivatization reagents are available. Online mass spectrometry approaches are attracting increasing interest for their ability to analyze multiple CPO species in real time without extensive sample preparation steps, reaching detection limits of about ppb for less polar oxidants. At the current state of metrological development, neither the methodologies based on chromatography nor those based on online mass spectrometry allow complete speciation of CPOs. Future trends and major challenges related to these approaches are discussed. [ABSTRACT FROM AUTHOR]

The present work investigates electrochemical oxidation of chlorine using cobalt oxide (Co3O4) nanoparticles synthesized through a co-precipitation method, resulting in a cubic lattice structure with space group Fd-3m (227). This study demonstrates that Co3O4 nanoparticles exhibit superior performance compared to noble electrocatalysts in chlorine evolution reactions (CERs). Key electrocatalytic parameters were optimized, with Co3O4 achieving an overpotential of 120 mV at a current density of 10 mA cm−2, a Tafel slope of 112 mV d−1 and a charge transfer resistance of 9.6 Ω. Additionally, wettability results revealed that cobalt oxide possesses minimal hydrophobicity, which helps in faster chlorine evolution process. We believe, this study provides valuable addition in understanding the designing of effective electrocatalysts for CER. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) membrane fouling and biological contamination problems faced by seawater desalination systems are microbiologically related. We used full-length 16S rRNA gene sequencing to assess the bacterial community structure and chlorine-resistant bacteria (CRB) associated with biofilm growth in different treatment processes under the winter mode of a chlorinated seawater desalination system in China. At the outset of the winter mode, certain CRB, such as Acinetobacter, Pseudomonas, and Bacillus held sway over the bacterial community structure, playing a pivotal role in biofouling. At the mode's end, Deinococcus and Paracoccus predominated, with Pseudomonas and Roseovarius following suit, while certain CRB genera still maintained their dominance. RO and chlorination are pivotal factors in shaping the bacterial community structure and diversity, and increases in total heterotrophic bacterial counts and community diversity in safety filters may adversely affect the effectiveness of subsequent RO systems. Besides, the bacterial diversity and culturable biomass in the water produced by the RO system remain high, and some conditionally pathogenic CRBs pose a certain microbial risk as a source of drinking water. Targeted removal of these CRBs will be an important area of research for advancing control over membrane clogging and ensuring water quality safety in the future. HIGHLIGHTS RO and chlorine disinfection of seawater desalination systems are important for the structural diversity of the bacterial community, and the composition of the bacterial community has changed significantly.; A number of CRBs typically associated with biofilm formation are important in the bacterial community structure and are present in large numbers in the RO-produced water.;

A continuous flow metal‐free protocol for the synthesis of sulfonyl chlorides from thiols and disulfides in the presence of nitric acid, hydrochloric acid and oxygen was developed. The influence of the reaction parameters was investigated under batch and flow conditions. Online 19F NMR was successfully implemented to investigate different reaction conditions within a single experiment. The sulfonyl chlorides were isolated (mostly in 70–81 % yield) after performing a simple aqueous washing procedure. In particular, the protocol was successfully operated for >6 hours to convert diphenyl disulfide to its corresponding sulfonyl chloride, achieving a throughput of 3.7 g h−1. The environmental impact of the protocol was assessed and compared to an existing continuous flow protocol using 1,3‐dichloro‐5,5‐dimethylhydantoin (DCH) as reagent. The process mass intensity (PMI) for the newly‐developed flow protocol (15) compared favorably to the DCH flow process (20). [ABSTRACT FROM AUTHOR]

Viscose-based carbon fibers (VBCFs) were chlorinated with CCl4 vapor to investigate the effect of chlorination temperature on their microwave properties. The maximum chlorine content of 2.0 mmol g−1 was obtained at 450 °C. TEM and SEM showed carbon nanostructures and surface morphology preservation, respectively. TGA and TPD MS confirmed the formation of carbon-oxygen and chlorine-carbon groups, including CCl3 groups. The prepared chlorinated VBCFs can effectively reflect X-band microwaves, with nearly constant reflection losses over a wide frequency range, and are characterized by minimum transmission losses of −22 dB. [ABSTRACT FROM AUTHOR]

At inflammatory sites, immune cells generate oxidants including H₂O₂. Myeloperoxidase (MPO), released by activated leukocytes employs H₂O₂ and halide/pseudohalides to form hypohalous acids that mediate pathogen killing. Hypochlorous acid (HOCl) is a major species formed. Excessive or misplaced HOCl formation damages host tissues with this linked to multiple inflammatory diseases. Previously (Redox Biology , 2020, 28, 101331) we reported that iodide (I⁻) modulates MPO-mediated protein damage by decreasing HOCl generation with concomitant hypoiodous acid (HOI) formation. HOI may however impact on protein structure, so in this study we examined whether and how HOI, from peroxidase/H₂O₂/I⁻ systems ± Cl⁻, modifies proteins. Experiments employed MPO and lactoperoxidase (LPO) and multiple proteins (serum albumins, anastellin), with both chemical (intact protein and peptide mass mapping, LC-MS) and structural (SDS-PAGE) changes assessed. LC-MS analyses revealed dose-dependent iodination of anastellin and albumins by LPO/H 2 O 2 with increasing I⁻. Incubation of BSA with MPO/H 2 O 2 /Cl⁻ revealed modest chlorination (Tyr286, Tyr475, ∼4 %) and Met modification. Lower levels of these species, and extensive iodination at specific Tyr and His residues (>20 % modification with ≥10 μM I⁻) were detected with increasing I⁻. Anastellin dimerization was inhibited by increasing I⁻, but less marked changes were observed with albumins. These data confirm that I⁻ competes with Cl⁻ for MPO and is an efficient HOCl scavenger. These processes decrease protein chlorination and oxidation, but result in extensive iodination. This is consistent with published data on the presence of iodinated Tyr on neutrophil proteins. The biological implications of protein iodination relative to chlorination require further clarification. [Display omitted] • Peroxidases, such as myeloperoxidase (MPO) damage proteins as sites of inflammation. • Iodide (I−) modulates MPO-induced protein damage and inhibits cross-linking. • Low I− levels cause a dramatic switch from methionine to tyrosine (Tyr) modification. • Hypoiodous acid (HOI) exposure results in selective Tyr and His iodination. • HOI induces only minor gross structural changes but enhances protein hydrophobicity. [ABSTRACT FROM AUTHOR]

With the use of the products of free-radical chlorination of indane as an example (data for tetralin are mentioned for comparison), it was shown that only their molecular formulas can be determined as a result of gas chromatography–mass spectrometry analysis, and the reaction mechanism was detailed on this basis. The structure refinement of the components requires an interpretation of their gas-chromatographic retention indices in the form of local additive schemes created for solving a specific problem under consideration. These schemes are sufficiently reliable if they are formed on the basis of data for objects containing all the structural elements of the molecules of characterized compounds. If this condition is not met (as in the case under consideration), the possibility of interpreting retention indices is fundamentally preserved; however, the accuracy of their estimates is significantly reduced and the volume of preliminary calculations increases considerably. The key fragment of the structure of chlorinated indane derivatives, which was almost not represented among the compounds characterized to date, is the chlorine atom in the alicyclic structural fragment in the α-position to the aromatic system. Secondary chlorine derivatives are formed as a result of dehydrochlorination of the primary reaction products with the subsequent addition of chlorine at the C=C double bonds. [ABSTRACT FROM AUTHOR]

N-nitrosodimethylamine (NDMA) is a potentially carcinogenic byproduct of disinfecting drinking water. NDMA has been classified as a Group B2 carcinogen by the U.S. Environmental Protection Agency (EPA). The pathway of NDMA formation during chlorination has been proposed; however, it is still necessary to identify the most influential factor in this process. The objective of this study was to compare the factors and conditions that lead to the formation of NDMA from dimethylamine (DMA) to identify the primary factors responsible for the occurrence of this compound in drinking water. The study examined the formation of NDMA in chlorinated water under seven different conditions, considering three factors (NO2−, NO3−, and NH3). All factors were maintained at their actual concentrations in tap or surface water. The highest levels of NDMA were observed at pH 6 when NO3− and NH3 were present, with concentrations of 22.7 ng/L and 9.79 ng/L, respectively. At pH 6, NDMA levels were observed to be 22 times higher than at pH 8. Chlorine alone was not sufficient to convert DMA to NDMA within a short period of time, specifically at least 5 h, in the absence of other factors. The concentration of NDMA increased to 41.6 ng/L in the presence of NH3. After 16 h, the presence of NO3− led to a gradual increase in NDMA levels to 19.0 ng/L. However, no further increase was observed at this point. The findings suggest that NO3− and NH3 are important factors of NDMA in chlorinated drinking water. Although previous mechanisms have not given much attention to these factors, they are expected to play a significant role in the formation of nitrosamines in both natural water and drinking water. Controlling the factors or pH appeared to be crucial for managing NDMA formation, and further research on reducing N-nitrosamines is necessary. [ABSTRACT FROM AUTHOR]

Dexamethasone (DEX) degradation was investigated using three UV-based advanced oxidation processes combined with sodium persulphate, hydrogen peroxide, and free chlorine in aqueous solutions in a bench-scale reactor. The goal was to determine which process would be the best option in terms of DEX degradation without the subsequent generation of toxic compounds. The process performance for DEX degradation followed the UV/S2O82−> UV/H2O2> UV/HOCl order under equal conditions. In the UV/S2O82− process, sulphate radicals led to a 70.4% DEX degradation. The experimental mineral inhibitory factors showed that nitrite and bicarbonate further decrease the efficiency of the UV/S2O82− process. In the optimal conditions, the UV/S2O8−2 process removed DEX by 100% and had a 74.1% mineralisation. Furthermore, the intermediates were detected using LC-MS/MS, and the cytotoxicity of the UV/S2O8−2 process effluent was evaluated using human embryonic kidney cultured cells. The treatment of DEX solution by the UV/S2O8−2 process significantly decreased the toxicity of the effluent. Therefore, it can be concluded that the UV/S2O8−2 process can be a reliable process for DEX degradation and detoxification in aqueous solutions. [ABSTRACT FROM AUTHOR]

The early stages of mussel farming are often inefficient with a large proportion of seed (spat) typically lost early in the production cycle. An effective approach for decreasing such losses is to grow spat to larger sizes in nursery systems prior to seeding. However, for such an approach to be commercially viable, spat must first be separated from their settlement substrates into a single seed format, that is, singulated. This study investigated the efficacy of three commercial protease enzymes (Enzidase PAP, PXT and BAP) and chlorine (NaOCl) in singulating Greenshell mussel (Perna canaliculus) spat from spat‐collector ropes. Two distinct experiments involved immersing segments of spat collector rope in seawater solutions with varying concentrations (2.5% or 5%) of each enzyme or chlorine (NaOCl) for different exposure times (10, 30 and 60 min for enzymes; 2 and 5 min for chlorine). After the singulation experiments, all spat were recovered with sieves and reintroduced into the tanks with renewed seawater. After 24 h of rearing, the recovery of alive spat was measured. Results indicate that in Experiment 1, involving spat ∼5 mm in size, the singulation rate was up to 65% for protease enzymes (i.e., in the case of 5% PAP at 30 min) and 61% for chlorine (i.e., at 5% for 2 min). In Experiment 2, involving spat ∼1.5 mm in size, the singulation rate was up to 85% for protease enzymes (i.e., in the case of 5% PXT for 60 min) and 78% for chlorine (i.e., of 2.5% for 5 min). However, these treatments generally resulted in elevated spat mortality, which was exacerbated by increasing concentrations and exposure times, resulting in recovery rates of up to 35% (i.e., for 2.5% PAP for 30 min) in Experiment 1 and 26.0% (i.e., for 5% chlorine for 2 min) in Experiment 2. These findings emphasise the necessity for consideration of chemical concentrations and exposure times to optimise the singulation process while highlighting challenges in achieving high post‐singulation survival rates. These insights contribute to ongoing efforts aimed at improving the efficiency and sustainability of mussel farming practices, demonstrating the potential utility of protease enzymes and chlorination in singulating spat from settlement substrate prior to their transfer to nursery systems for further ongrowing. For mussel spat to be grown in nursery culture systems they must first be separated from their associated settlement substrate (i.e., singualted). This work demonstrated that protease enzymes and chlorination is an effective approach for separating Greenshell mussel spat from spat‐catching ropes. [ABSTRACT FROM AUTHOR]

The recovery of As from copper anode slime by chlorination leaching--NaH2PO2 selective reduction process was studied. The effects of liquid volume to solid mass ratio, initial acidity, leaching temperature, initial Cl- mass concentration and leaching time on the leaching rate of As. The effects of reduction temperature, molar ratio of NaH2PO2 to As and reduction time on the precipitation rate of As were investigated. The results show that the optimum chlorination leaching conditions are initial acidity of 220 g/L, liquid volume to solid mass ratio of 6/1, leaching temperature of 70 °C, initial Cl mass concentration of 150 g/L and leaching time of 2.5 h. The optimum reduction conditions are reduction temperature of 80 °C, molar ratio of NaH2PO2 to As of 2/1, reduction time of 2 h. Under the optimal conditions the average mass fraction of As is 90.44%, and the product quality can meet the refining requirements of elemental arsenic. [ABSTRACT FROM AUTHOR]

Chlorination is a common chemical modification process of soft wheat flour to prepare high-ratio cakes. Due to safety and labeling concerns of flour chlorination, alternatives to chlorination have been researched. Atmospheric Cold Plasma (ACP) is an emerging technology which is applicable for a wide range of food and biological components, including cereal grain products. The potential of ACP as an alternative to chlorination for high-ratio cakes has not been researched. Soft wheat flour was treated at 50 kV, 60 kV, and 70 kV each for 5, 6, and 7 min and compared to untreated and chlorinated wheat flour. High-ratio cakes were prepared from the chlorinated, treated, and untreated soft wheat flour and their properties were compared. Changes in the flour properties and the high-ratio cakes were observed at different treatment conditions. It was found that after 50 kV, 6 min, 50 kV, 7 min and 60 kV, 6 min had the better flour pasting properties, higher cake volume, and better texture properties as compared to untreated wheat flour and chlorinated wheat flour. This determines the potential of the application of ACP as an alternative to chlorination or to reduce the use of chlorination in soft wheat flour. [ABSTRACT FROM AUTHOR]

Electrochemistry offers tunable, cost effective and environmentally friendly alternatives to carry out redox reactions with electrons as traceless reagents. The use of organoiodine compounds as electrocatalysts is largely underdeveloped, despite their widespread application as powerful and versatile reagents. Mechanistic data reveal that the hexafluoroisopropanol assisted iodoarene oxidation is followed by a stepwise chloride ligand exchange for the catalytic generation of the dichloroiodoarene mediator. Here, we report an environmentally benign iodine(I/III) electrocatalytic platform for the in situ generation of dichloroiodoarenes for different reactions such as mono- and dichlorinations as well as chlorocyclisations within a continuous flow setup. Electrochemistry offers tunable, cost effective and environmentally friendly alternatives to carry out redox reactions but the use of organoiodine compounds as electrocatalysts is largely underdeveloped. Here, the authors report an environmentally benign iodine(I/III) electrocatalytic platform for the in situ generation of dichloroiodoarenes for different reactions within a continuous flow setup. [ABSTRACT FROM AUTHOR]

Ribavirin (RBV), which is extensively used to treat viral diseases such as COVID-19, is considered one of the major emerging contaminants due to its long-term existence and health risk in the aqueous environmental system. However, research on effective removal of RBV still remains insufficient. In this study, we investigated the RBV degradation kinetics and mechanism in UV/chlorine/Fe(II) process. The degradation rate constant kobs-RBV of RBV was 2.52 × 10−4 s−1 in UV/chlorine/Fe(II) process, which increased by 1.6 times and 1.3 times than that in chlorine alone and UV/chlorine process, respectively. Notably, trace amount Fe(II) promoted RBV degradation in UV/chlorine system through Fe2+/Fe3+ cycles, enhancing the yield of reactive species such as HO· and certain species reactive chlorine radicals (RCS). The contributions of HO· and RCS toward RBV degradation were 53.91% and 16.11%, respectively. Specifically, Cl·, ClO·, and Cl2·− were responsible for 8.59%, 2.69%, and 4.83% of RBV removal. The RBV degradation pathway indicated that the reactive species preferentially attacked the amide moiety of RBV, which cleaved the ether bond and the hydroxyl group. The toxicity evaluation of RBV degradation products elucidated that UV/chlorine/Fe(II) process was beneficial for RBV detoxification. [ABSTRACT FROM AUTHOR]

Addressing the issue that the Bayer process is not suitable for low-grade bauxite, carbochlorination was proposed to recover aluminum and silicon from low-grade bauxite. This study focused on the behavior of aluminum and silicon during the carbochlorination process of low-grade bauxite. The impact of various process parameters on the chlorination efficiency was investigated, and the chlorination mechanism and kinetics of aluminum and silicon chlorination in bauxite were analyzed and discussed. Under optimal experimental conditions, the chlorination efficiency of Al2O3 and SiO2 reached 94.93% and 86.32%, respectively. The carbochlorination of aluminum and silicon in bauxite adhered to a shrinking, unreacted core model governed by gas diffusion within the product layer. This process can be bifurcated into two stages. Additionally, calculations were conducted to determine the apparent activation energy and reaction order of the chlorination processes involving Al2O3 and SiO2. Examining the chlorination mechanism revealed that the bauxite carbochlorination encompasses transformations among various minerals. Notably, the aluminum component prefers to participate in the carbothermal chlorination reaction over silicon. [ABSTRACT FROM AUTHOR]

This study was aimed to reduce the clogging ratio using two waters qualities Sumael (LSI) and Bazalan (LSII). The physical treatment was carried out using complete filtration unit composed of three of filters (Hydrocyclone, Sand, and Disc filters) and application of hypo chloride (Ca (OCl)2 ) 2 ppm as chemical treatment. Generally, physical treatment was more effective than chemical treatment to reduce clogging ratio for Sumael water (LSI). In contrast, for Bazalan water (LSII), the chlorine application was more practical to reduce clogging ratio. The results showed after the period of 320 hr, filtration reduces the clogging ratio for Sumael water (LSI) was 67.77% at clogging ratio 12.51%corresponding to 28.53% at clogging ratio 27.74%for chlorination when the clogging ratio for no treat was 38.82%. As opposed to Bazalan water (LSII), the improvement ratio for chlorination was 14.36% at clogging ratio was 7.56%. In case for filtration was improved to 10.42% when clogging ratio was 8.00% in comparing with no treat clogging ratio was 8.93%. [ABSTRACT FROM AUTHOR]

Based on a literature review, the relevance and necessity of processing e‑waste are shown. Pyro-, hydro- and biometallurgical methods for processing e‑waste are briefly described, and the advantages and disadvantages of existing technologies are compared. The efficiency and the environmental and health impacts of various technologies are analyzed. The low-temperature chlorination technology applied to e‑waste processing is given a thermodynamic interpretation to obtain additional information necessary for better understanding of the behavior of gold and other non-ferrous metals with low metal content. The mechanism of the interaction between e‑waste elements and gaseous chlorine during low-temperature roasting was studied. The behavior of metals at low temperatures of chlorination of e‑waste (below 673 K) was assessed from the changes in the thermodynamic quantities of the system. Thermodynamic calculations were conducted to determine the Gibbs free energy (Δ G T 0 ) of the reactions between e‑waste elements and gaseous chlorine at various temperatures. Based on the thermodynamic calculations of the reactions of precious (gold, silver, platinum, palladium) and other non-ferrous metals (Cu, Pb, Zn) with gaseous chlorine at low chlorination temperatures of 323–673 K, it was established that it is possible to selectively recover gold as sublimates Au2Cl6(g) and to produce a solid-phase cinder containing solid chlorides of precious and non-ferrous metals. The low-temperature chlorination roasting of e‑waste is a good prerequisite for the integrated recovery of gold and other precious and non-ferrous metals with high efficiency. The obtained results will be used for the selection, justification, and science-based design of innovative technology for processing e‑waste, using not only gaseous chlorine, but also solid chlorine-containing reagents (CaCl2, NaCl). [ABSTRACT FROM AUTHOR]

This article explores the incorporation of fluorine atoms into organic compounds and its potential impact on their chemical and biological properties. Specifically, it focuses on the gem-difluoromethylene functionality as a bioisostere of the methylene group, which has applications in drug discovery. The article presents a detailed synthetic method for introducing the gem-difluoromethylene group using a building block approach. The method involves the preparation of sulfonate esters from sulfonyl chlorides and bromodifluoroethanol, followed by a photochemical Smiles rearrangement to generate the desired compound. Additionally, the article describes a synthesis method for gem-difluorinated thiophene, a compound that can be used as a building block in medicinal chemistry. The synthesis involves a multicomponent cyclization and oxidative chlorination reaction, followed by a radical Smiles rearrangement mediated by visible light. The authors provide supporting information and acknowledge the assistance of others in the analysis. [Extracted from the article]

Chlorination has been demonstrated to be an effective method for the prevention and reduction in emitter biological blockage in drip irrigation systems. The injected chlorine dose is generally determined by chlorine concentration at the terminal of the laterals which may lead to a high concentration of residual chlorine at the front of the system and bring detrimental impact to the soil environment and growth of crops, especially in large irrigation units with long laterals. A two-season experiment was undertaken to determine the effects of chlorine disinfection and lateral length on soil NO3-N, enzyme activities, and maize yield under wastewater drip irrigation. The experiments were constructed with lateral lengths ranging from 20 to 80 m and injection chlorine concentrations at the end of laterals ranging from 2 to 6 mg L−1. Lateral length had a major impact on enzyme activities in the partial growth stage, although the effects of lateral length and chlorine concentration on soil nitrogen content and maize yield were negligible. Enzyme activity and soil nitrogen concentration decreased throughout the lateral length as a result of chlorination. A higher detrimental impact on soil characteristics and maize yield is probably going to result from a high concentration of chlorine and a long lateral length mode. The maize yield peaked at L80 with a concentration of 2 mg L−1 chlorine, while it peaked at L40 with 6 mg L−1 chlorine concentration. A chlorination scheme with long lateral length and low chlorine concentration is recommended in consideration of maize yield and minimizing potential negative effects on the soil environment. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) is known to be effectively etched by O2-based plasma with a 10%–20% amount of Cl2, while it is less etched by pure O2-based or Cl2-rich plasma. In this work, reaction paths and energy profiles on a metallic Ru surface were calculated in density functional theory (DFT) simulations to reveal the chemical role of the small amount of Cl2 in the O2-based plasma for Ru etching. We prepared three Ru(0001) surfaces with (1 × 1) adatoms in which chemisorption sites were occupied by O and Cl adatoms. Subsequently, we assumed that convex Ru moieties, which are precursors to form volatile Ru species, were formed on the surface and that they were oxidized by the irradiation of O2-rich plasma. In each Ru(0001) surface, we calculated the production and activation energies of each elementary reaction path to desorb the volatile Ru products. Compared with the surface where all chemisorption sites were covered with O, both energies decreased in locations where some chemisorption sites were replaced by Cl. Our DFT-based research showed that a small amount of Cl2 in the O2/Cl2 plasma contributes to decreasing the production and activation energy to form volatile Ru products on the Ru surface, resulting in the etching rate being increased. [ABSTRACT FROM AUTHOR]

Chloride concentration is one of the important factors that seriously affect the electrolysis of zinc sulfate. The copper slag used in the copper slag dechlorination method has low activity due to long-term storage, resulting in an unstable dechlorination effect. Therefore, a highly active copper deep dechlorination process is proposed to achieve the purpose of stable and deep dechlorination. In this study, the copper slag was pre-oxidized, and high-activity copper was obtained by adding an appropriate amount of zinc powder. The experimental results show that the dechlorination rate reaches 90.41% when the initial solution acidity is 30 g/L and the ratio of copper slag to zinc powder is 7:6; the solution was treated at room temperature (20°C) for 30 min. When the amount of zinc powder was increased 8 times, the removal of chloride ions reached 95.43% and the content of chloride ions in the solution was reduced to 20 mg/L. The dechlorination effect is much lower than the standard of chlorine (< 100 mg/L) in the zinc electrolysis process, realizing deep dechlorination. The process ensures the smooth progress of zinc electrolysis and has great application prospects. [ABSTRACT FROM AUTHOR]

South Africa is currently confronted with significant challenges related to the compliance of incineration facilities as incinerators are a major source of polychlorinated dibenzo-pdioxins and polychlorinated dibenzofurans (PCDD/Fs) and have become a significant issue in both environment and public health. The objective of this study was to assess the effectiveness of activated carbon injections in absorbing PCDD/Fs from the flue gas emissions. The ∑TEQ was initially calculated at 46.36 ng I-TEQ Nm-³ but saw a substantial reduction to 10.64 ng I-TEQ Nm-³ following AC treatment. This study was able to achieve an overall removal efficiency of 85%. Notably, highly chlorinated congeners exhibited higher removal efficiencies, indicating the selective adsorption properties of activated carbon. It was also observed that there was a correlation between PCDD/F congeners and flue gas compositions during the activated carbon treatment as congeners reacted with HCl to reduce the chlorine in synthesis of PCDD/Fs. While the activated carbon injections did lead to a notable reduction in PCDD/Fs, the surface area and porosity of the activated carbon also influenced removal efficiency. It is recommended that activated carbon with higher absorption capacity be used to enhance overall efficiency, with further modification to increase surface area and absorption for even greater effectiveness. However, despite the promise shown by activated carbon treatment in reducing PCDD/F emissions, further optimization and technological advancements are necessary to meet stringent regulatory standards. [ABSTRACT FROM AUTHOR]

The first chloroaluminoborate, CsAlB3O6Cl, with innovative AlO3Cl tetrahedra and a perfect planar arrangement of [B3O6] groups, was structurally designed and synthesized via chlorination of [AlO4] tetrahedra. Simultaneously, the smooth introduction of the [AlO3Cl] group into borates initiates the development of a chloroaluminoborate and greatly enriches the structural chemistry of aluminoborates. [ABSTRACT FROM AUTHOR]

Water availability and quality are still challenges around the world, but access to safe drinking water is essential for human development. This study analyzed the chemical parameters of drinking water quality in the Santa Cruz de la Sierra region of Bolivia. Residual chlorine, pH and concentration of dissolved solids were measured in water supplied by drinking water and basic sanitation service providers (EPSA). The water quality results indicated that the water supplied met the requirements established by the Bolivian Standard NB 512 in terms of residual chlorine, pH and concentration of dissolved solids. However, a decrease in residual chlorine concentration was observed as the water moved away from the disinfection point. Microbiological testing is recommended to ensure the absence of viable organisms in the distributed water. In conclusion, this study highlights the importance of chlorination, as the only treatment performed in the study area, the pH and the concentration of dissolved solids as indicators of drinking water quality. Automation of chlorination processes and continuous monitoring of these parameters is suggested to ensure a safe and high-quality water supply in the study area. [ABSTRACT FROM AUTHOR]

The presence of CECs in aquatic systems has raised significant concern since they are potentially harmful to the environment and human health. Eliminating CECs has led to the development of alternatives to treat wastewater, such as advanced oxidation processes (AOPs). The ultraviolet-mediated activation of monochloramine (UV/NH2Cl) is a novel and relatively unexplored AOPs for treating pollutants in wastewater systems. This process involves the production of amino radicals (•NH2) and chlorine radicals (Cl•) from the UV irradiation of NH2Cl. Studies have demonstrated its effectiveness in mitigating various CECs, exhibiting advantages, such as the potential to control the amount of toxic disinfection byproducts (TDBPs) formed, low costs of reagents, and low energy consumption. However, the strong influence of operating parameters in the degradation efficiency and existence of NH2Cl, the lack of studies of its use in real matrices and techno-economic assessments, low selectivity, and prolonged treatment periods must be overcome to make this technology more competitive with more mature AOPs. This review article revisits the state-of-the-art of the UV/NH2Cl technology to eliminate pharmaceutical and personal care products (PPCPs), micropollutants from the food industry, pesticides, and industrial products in aqueous media. The reactions involved in the production of radicals and the influence of operating parameters are covered to understand the formation of TDBPs and the main challenges and limitations of the UV/NH2Cl to degrade CECs. This review article generates critical knowledge about the UV/NH2Cl process, expanding the horizon for a better application of this technology in treating water contaminated with CECs. [ABSTRACT FROM AUTHOR]

Chlorination has become a commonly used strategy in various chemical industries. Environmentally friendly chlorination of C–H bonds to directly generate C–Cl bonds is also in high demand in organic synthesis. Herein, we report a new and green highly selective method of chlorination of C(sp³ )–H moieties with the inorganic salt MgCl2, cocatalyzed by visible light/FeCl3 under strong oxidant-free and ambient conditions. The reaction was applied to the chlorination of different methylarene α-hydrogen and cyclic hydrocarbon C–H moieties with high conversion and kinetic selectivity. The chlorination of toluene α-Hs proceeded in 91% yield, with 98% selectivity and 95% conversion. Electron–spin resonance studies of the DMPO-Cl (5,5-dimethyl-1-pyrroline-N-oxide) radical revealed that the reaction mechanism involved a free radical process. [ABSTRACT FROM AUTHOR]

Chlorination has become a commonly used strategy in various chemical industries. Environmentally friendly chlorination of C–H bonds to directly generate C–Cl bonds is also in high demand in organic synthesis. Herein, we report a new and green highly selective method of chlorination of C(sp³ )–H moieties with the inorganic salt MgCl2, cocatalyzed by visible light/FeCl3 under strong oxidant-free and ambient conditions. The reaction was applied to the chlorination of different methylarene α-hydrogen and cyclic hydrocarbon C–H moieties with high conversion and kinetic selectivity. The chlorination of toluene α-Hs proceeded in 91% yield, with 98% selectivity and 95% conversion. Electron–spin resonance studies of the DMPO-Cl (5,5-dimethyl-1-pyrroline-N-oxide) radical revealed that the reaction mechanism involved a free radical process. [ABSTRACT FROM AUTHOR]