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Chlorine bleaching technology (C process, CEH process, H process and theirs combination), which was identified as a primary formation source of PCDD/Fs, is still widely used by the vast majority of Chinese non-wood pulp and paper mills (non-wood PMs). The purpose of this study was to provide information and data support for further eliminating dioxin for non-wood PMs in China, and especially to evaluate the PCDD/Fs release reduction for those mills converting their pulp bleaching processes from CEH to ECF. The PCDD/Fs concentrations of the bleached pulp and bleaching wastewater with ECF bleaching were in the ranges of 0.13-0.8 ng TEQ kg -1 , and 0.15-1.9 pg TEQ L -1 , respectively, which were far lower than those with CEH process, indicating that the ECF process is an effective alternative bleaching technology to replace CEH in Chinese non-wood PMs to reduce dioxin release. The release factor via flue gas of the alkali recovery boiler in Chinese non-wood PMs was first reported to be 0.092 μg TEQ Ad t -1 in this study. On the assumption that pulp bleaching processes of all Chinese non-wood PMs were converted from CEH to ECF, the annual release of PCDD/Fs via the bleaching wastewater and bleached pulp would be reduced by 79.1%, with a total of 1.60 g TEQ., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Six elemental chlorine-free bleaching sequences were studied to see their effect on quality of pulp produced and quantity of pollutants generated during bleaching of wheat straw soda pulp. Impact of parameters like adsorbable organic halogens (AOX), chemical oxygen demand (COD), biochemical oxygen demand (BOD) and sodium adsorption ratio, pH and total dissolved solids generated during bleaching on environment as index of global pollution (I GP ) was also studied. The purpose of the study was to investigate six elemental chlorine-free bleaching sequences to compare the pulp quality, effluent properties and their impact on environment. An oxygen delignification stage before D 0 E OP D bleaching sequence reduced the AOX, COD, colour and BOD by 44%, 42%, 36% and 33%, respectively, whereas an ozonation stage before bleaching reduced the same by 70%, 66%, 73% and 60%, respectively, as compared to those of control. The generation of pollutants as AOX, COD, colour and BOD was reduced further by 88%, 80%, 90% and 77%, respectively, with the use of short bleaching sequences (DD, DP and PD) as compared to those of control. The environmental impact as I GP with D 0 E OP D bleaching sequence was 2.65 which got reduced to 1.44 with bleaching sequence OZPD. Bleaching sequence OZD 0 E OP D was found the most effective for improving brightness and whiteness of the pulp, whereas short bleaching sequence OZPD found the most effective for reducing generation of pollutants during bleaching among different bleaching sequences studied. Graphical abstract.

The article reviews the transition from bleaching kraft pulp with elemental chlorine to bleaching with chlorine dioxide with respect to formation of chlorinated dioxins and furans (PCDD/Fs). New data is also presented for bleaching with 100% chlorine dioxide and the effect of elemental chlorine impurities. The typical fingerprint of PCDD/Fs in pulp bleached with elemental chlorine was unique compared to all other sources such as incineration and metallurgic processes. 2,3,7,8-TCDD and 2,3,7,8-TCDF were the dominating congeners formed during the period pulp was bleached with elemental chlorine. Elimination of unchlorinated precursors lowered, but did not eliminate, the formation of 2,3,7,8-TCDD and 2,3,7,8-TCDF. The formation of 2,3,7,8-TCDD and 2,3,7,8-TCDF increases exponentially with the amount of elemental chlorine used. Replacing elemental chlorine with chlorine dioxide (with levels of elemental chlorine contamination of <0.3% in the chlorine dioxide) in pulp bleaching eliminates the formation of 2,3,7,8-TCDD and 2,3,7,8-TCDF. PCDD/Fs can also be found in background levels in ecosystems, food, soil and air as well as in unbleached pulp, bleached pulp, and paper and fiber products. Thus, the only way to determine if PCDD/Fs are present from bleaching is to make a full congener analysis and compare to known sources and processes as well as to laboratory blanks and unbleached reference samples., (Copyright © 2019 The Author. Published by Elsevier Ltd.. All rights reserved.)

The effectiveness of a biorefinery based on an HWE-Kraft-ECF bleaching process and the end use of pulp was systematically evaluated. Using a P-factor of 198, nearly 30% of xylan-based sugars were recovered. The resulting pulp and paper properties were found to be comparable with the control. A maximum xylan-based sugar recovery of nearly 50% was achieved at a P-factor of 738. Although the strength of this P-factor induced handsheet was lower than that of the control by about 20%, the corresponding pulp was sufficient for dissolving pulp application. However, once the P-factor rose above 1189, hemicellulose sugars were significantly degraded into furans; pulp and paper properties were also deteriorated due to cellulose degradation, lignin deposition and condensation. Thus, considering the different end use of pulps, the performance of an HWE-based biorefinery could be balanced by its HWE severity., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Scheme 1 The illustration of the synthesis of dual-emission type N, Cl-doped carbon dots by a simple hydrothermal route and the implications. [Display omitted] • Dual-emission N, Cl-CDs with strong orange fluorescence were simply synthesized. • The N, Cl-CDs exhibited precise sensing toward VB 2 , VB 9 , VB 12 in aqueous solution. • Visually semiquantitative detection of three VBs were performed on test strip. • The detection of VBs were successfully applied in real samples. Although a few of fluorescent probes based on carbon dots (CDs) for vitamin B (VB) determination have been emerged, none of them can realize the detection of different kinds of VB. In this paper, nitrogen, chlorine co-doped dual-emission CDs (N, Cl-CDs) with emissions at 404 nm and 595 nm have been easily synthesized. VB 2 , VB 9 and VB 12 can all induce obvious fluorescence turn-off response toward the N, Cl-CDs. Based on that, three types of VBs are quantitatively and sensitively evaluated in aqueous solution with wide concentration ranges of 14.9–135.0 μM, 34.7–89.8 μM and 29.8–79.8 μM, respectively. Importantly, visual semiquantitative detection of VBs on a test strip are also proposed. Moreover, the current N, Cl-CDs have been successfully applied to the detection of VBs in real samples. The N, Cl-CDs are sensitively multifunctional sensors for three kinds of VBs in aqueous solution and the visual semiquantitative detection by test paper assay is simple, portable and inexpensive. [ABSTRACT FROM AUTHOR]

Long-term immobilization ratios of strontium (Sr2+) and cesium (Cs+) in paper sludge ash-based geopolymer (PS-GP) were investigated in one year. PS-GP paste specimens were prepared in the conditions of 20 °C and 100% R.H., using two kinds of paper sludge ash (PS-ash). Two kinds of alkaline solution were used in the PS-GP as activator. One was prepared by diluting aqueous Na-disilicate (water glass) with seawater. Another was a mixture of this solution and caustic soda of 10 M concentration. When seawater was mixed into the alkaline solution, unstable fixations of Sr2+ and Cs+ were greatly improved, resulting stable and high immobilization ratios at any age up to one year, no matter what kind of PS-ash and alkaline solution were used. Element maps obtained by EPMA exhibited nearly even distribution of Cs+. However Sr2+ was biased, making domains so firmly related to Ca2+ presence. The mechanism that seawater stabilizes immobilization of Sr2+ and Cs+ was discussed in this study, but still needs to further investigation. Chemical composition analyses of PS-GP were also conducted by SEM-EDS. Two categories of GP matrix were clearly observed, so called N-A-S-H and C-A-S-H gels, respectively. By plotting in ternary diagrams of SiO2-(CaO + Na2O)-Al2O3 and Al2O3-CaO-Na2O, compositional trends were discussed in view of ‘plagioclase gels’ newly found in this study. As a result, it is suggested that the N-A-S-H and C-A-S-H gels should be strictly called Na-rich N-C-A-S-H and Ca-rich N-C-A-S-H gels, respectively.

In recent decades, metal-containing nanocomposites have attracted considerable attention from researchers. In this work, for the first time, a detailed analysis of the preparation of reactive indicator papers (RIPs) based on silver-containing nanocomposites derived from silver fumarate was carried out. Thermolysis products are silver-containing nanocomposites containing silver nanoparticles uniformly distributed in a stabilizing carbon matrix. The study of the optical properties of silver-containing nanocomposites made it possible to outline the prospects for their application in chemical analysis. RIPs were made by impregnating a cellulose carrier with synthesized silver fumarate-derived nanocomposites, which change their color when interacting with chlorine vapor. This made it possible to propose a method for the determination of chloride ions with preliminary oxidation to molecular chlorine, which is then separated from the solution by gas extraction. The subsequent detection of the active zone of RIPs using colorimetry makes it possible to identify mathematical dependences of color coordinates on the concentration of chloride ions. The red (R) color coordinate in the RGB (red-green-blue) system was chosen as the most sensitive and promising analytical signal. Calibration plots of exponential and linear form and their equations are presented. The limit of detection is 0.036 mg/L, the limits of quantification are 0.15–2.4 mg/L, and the time of a single determination is 25 min. The prospects of the developed technique have been successfully shown in the example of the analysis of the natural waters of the Don River, pharmaceuticals, and food products. [ABSTRACT FROM AUTHOR]

The simultaneous detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater samples was performed. In this report, we designed and fabricated functionalized paper test strips featuring detection zones that use 3-aminopropyltriethoxysilane (APTES) for the immobilization of chromogenic substrates to detect free chlorine, hydrogen sulfide and formaldehyde. After multiple chromogenic reactions, red, blue and purple colors were obtained on the detection zones and analyzed using a smartphone. Under optimum conditions, the paper test strips showed 1.7, 1.8 and 1.7 orders of magnitude for free chlorine, hydrogen sulfide and formaldehyde, respectively. This sensitivity is caused by the formation of homogeneous complexes on detection zones resulting from the chromogenic reagents immobilized on the detection zone via APTES. Through this strategy, free chlorine, hydrogen sulfide and formaldehyde analysis was achieved within 5 min with detection limits of 0.08, 0.14 and 0.13 mg L−1, respectively. The developed paper test strip was able to selective detection of free chlorine, hydrogen sulfide and formaldehyde even in the presence of common interfering agents therefore, the test strip was highly selective. In a further demonstration, the developed functionalized paper test strip was successfully used for simultaneous detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater in the field and exhibited with high precision and accuracy in detecting free chlorine, hydrogen sulfide and formaldehyde in wastewater samples. Compared to other methods, this assay was advantageous in terms of its low detection limit, time savings, good stability and highly portable format, which facilitates rapid on-site environmental monitoring with a smartphone. Image 1 • A functionalized paper strip test enables two-fold improvement of detection limit. • Simultaneous detection of free chlorine, hydrogen sulfide and formaldehyde was achieved within 5 min with low detection limits. • A platform integrating functionalized paper strip test with a smartphone was successfully applied for ready-to-use for detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • A LIBS methodology for liquid sample analysis was developed and tested. • Common paper sheets are a convenient Ca source for molecular recombination. • Nanosecond-laser ablation is capable of breaking strong fluorine-carbon bonds. • Nebulization-assisted LIBS can be implemented for online screening of halogens. Halogen determination in liquid matrices with Laser-Induced Breakdown Spectroscopy (LIBS) is still a largely unexplored area of research. Together with the intrinsic problematics of liquid samples in LIBS analysis, halogen atomic emission is hard to observe without experimental modifications (e.g. vacuum chambers for VUV resonant lines or controlled He atmospheres for enhanced IR lines) or without switching to indirect determination via halide molecules emission. For the latter, the presence of an alkali-earth metal element is necessary. Previous works have explored CaCO 3 pellets as a substrate provider of Ca, and a nebulization-assisted methodology, with great potential for online implementation, has been successfully tested with synthetic and real F-containing samples. However, manufacturing pellets is a time- and reagent-consuming process not suitable for an online analysis technique and a more convenient substrate is needed. In the present work, different kinds of paper, from regular office paper to oil-painting sheets, are tested to explore its feasibility as a Ca-containing solid target. Different sources of F were also considered including inorganic fluoride and fluorocarbon containing samples. Moreover, both fluorine and chlorine determination via molecular emission are considered, achieving limits of detection (LODs) of 5 ppm and 192 ppm, respectively; a common metal (Zn) is also determined via atomic emission to test its validity for multi-elemental microanalysis, with a LOD of 5 ppm. [ABSTRACT FROM AUTHOR]

Abstract A new chemosensor in the form of indicator paper, which is sensitive to chlorine and bromine concentrations, is proposed. A simple technique of sensor preparation in a laboratory without expensive reagents is described. The method provides uniform and reproducible distribution of the reagent. A possibility to use the sensor for chemical analysis when combining with dynamic gas extraction with the application of scanner technologies and color image processing is demonstrated. Sensitive and selective techniques of chlorine, bromine, chloride, and bromide determination have been developed. The limits of detection of bromine, chlorine, bromide, and chloride have been found to be 0.06, 0.28, 0.5 and 1.4 μmol L−1 respectively. A scheme of successive determination of these analytes in the same sample including selective halides oxidation is proposed. In the simple and available set-up used for dynamic gas extraction, sample decomposition, oxidation of halide-ions and extraction of the formed halogen take place simultaneously while the color reaction of halogen interaction with the sensor is conducted out of the analyzed solution with reagents. This approach provides high selectivity and good analytical characteristics of analysis of such complex samples as foods, pharmaceutical formulations, and different water objects. The method is easy-to-use, cost-effective, time-efficient and promising for determination of other volatile compounds. Graphical abstract fx1 Highlights • Chlorine, bromine, chlorides, bromides detection in the same sample by dynamic gas extraction and paper sensor is proposed. • The method combines high selectivity and sensitivity in complex matrices. • Direct determination of above listed analytes in samples is possible with no sample pretreatment. • The method is easy-to-use, cost-effective, time-efficient and promising for determination of other volatile compounds. [ABSTRACT FROM AUTHOR]

The concentration of free chlorine used for disinfecting drinking water, recreational water, and food processing water is critical for environmental and human health conditions, and should be controlled within stipulated ranges. This report, for the first time, describes a paper-based electrochemical free chlorine sensor fabricated by hand-drawing. The electrical resistivity of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) chemoresistor increases when it is exposed to free chlorine in water due to oxidation reactions. Because the relative change of the electrical resistance represents the sensor's response, the sensor can be fabricated by hand-drawing with different shapes and dimensions. The fabrication steps are all at room temperature, require no instrumentation or equipment, and can be carried out by untrained personnel. The fabricated sensor is mechanically stable, reusable, has a wide sensing range, and can accurately measure free chlorine concentrations in real water samples. Therefore, the low-cost, hand-drawn free chlorine sensor is of great significance for water quality monitoring in less developed areas where fabrication facilities, analytical equipment, and trained personnel are limited, but the need for analytical devices is critical. In addition to the free chlorine sensor demonstrated in this study, other types of PEDOT:PSS-based sensors and electronic devices can be fabricated by the developed hand-drawing process. [ABSTRACT FROM AUTHOR]

As the main water treatment material, polymeric membranes inevitably suffer from membrane fouling. In this work, novel lignin‐based polyester composite nanofiltration membranes (NFM) with ethanol and chlorine resistance were fabricated via interfacial polymerization. Lignin alkali (LA), a green lignin derivative, typically treated as chemical waste in the paper industry, was employed as the aqueous monomer, trimesoyl chloride (TMC) is served as the organic monomer. The structure and separation properties of the lignin‐based NFM were studied, revealing that the dense polyester separation layer may show good performance for dye removal. The rejections of the optimized LA/TMC‐3 membrane with an excellent permeation flux of 13.9 kg m−2∙h−1 for rose Bengal sodium salt, brilliant blue, congo red, rhodamine B, MgSO4, and NaCl are 97.6%, 97.3%, 97.8%, 71.34%, 51.4%, and 31.8%, respectively. Moreover, the LA/TMC‐3 membrane also shows long‐term tolerance in ethanol and sodium hypochlorite solution; the rejection of LA/TMC‐3 to dye only decreases 8% after 8 days when immersed in alcohol, while the normalized rejection maintains 94% after 4000 ppm‐hours of continuous exposure to chlorine. This lignin‐based polyester membrane may broaden the sustainable utilization sphere of lignin derivatives, at that provide a referable direction for the development of membrane materials. [ABSTRACT FROM AUTHOR]

The current Australian and New Zealand default guideline value of 3 µg Cl/L for total residual chlorine in freshwaters is largely based on acute data converted to chronic data using a default acute to chronic ratio of 10, without consideration of chlorine decomposition. Given the rapid decomposition of chlorine, initially as hypochlorite and then as chloramine, it is appropriate to consider a guideline value based on short-term (acute) toxicity rather than one based on longer-term chronic data, as has been recommended for chlorine in marine waters. The literature on the fate of chlorine in drinking water discharged to freshwaters and on the ecotoxicity of total residual chlorine has been reviewed, and on the basis of this, revised default guideline values were derived for both hypochlorite and chloramine in freshwater using a species sensitivity distribution of toxicity data. The values for 95% species protection were 7 and 9 µg Cl/L as total residual chlorine, respectively. The former would apply to any total residual chlorine-containing effluent, but in the case of drinking water where dechlorination has been undertaken, the chloramine-based default guideline value is likely to be more appropriate. Both are likely to be conservative because they were largely based on toxicity testing under continuous flow-through conditions. They will apply at the edge of the mixing zone, and the variable receiving water concentration at this point might best be determined from a time-weighted average total residual chlorine concentration. Environ Toxicol Chem 2021;40:1341-1352. © 2021 SETAC., (© 2021 SETAC.)

• Sarkanda has potential to be utilized for pulp and paper production. • Chemical properties of sarkanda were found comparable with other agro-residues. • Sarkanda pulp has better morphological properties compared to wheat straw and rice straw. • Using ECF and TCF sequences pulp was bleached to 85.7 % and 81.9 % ISO brightness. • Sarkanda pulp has higher physical properties compared to bagasse and rice straw pulps. A lignocellulosic non-wood material sarkanda available in abundance as waste, was evaluated for chemical constituents, pulping behavior, morphological properties, bleaching behavior and paper handsheet strength properties. Present study reveals that sarkanda contains cellulose 36.2 ± 0.5 %, hemicelluloses 35.2 ± 0.41 %, lignin 21.2 ± 0.22 % and ash 8.2 ± 0.3 %. Soda-anthraquinone pulping of sarkanda using 15 % active alkali resulted in unbleached pulp with 14.7 kappa number, 16.0 cP viscosity and 54.6 % pulp yield. With use of elemental chlorine free bleaching sequence, OD 0 E OP D, final bleached pulp achieved 85.7 % ISO brightness, whereas, using total chlorine free bleaching sequence, OZ EOP P O P O , the brightness obtained was 81.9 % ISO. Elemental chlorine free bleached sarkanda pulp had tensile index of 39.4 N m/g, burst index of 3.4 kN/g and tear index of 5.7 mN m2/g. The study exhibits that sarkanda has potential to be utilized for papermaking. Such approach of using non-wood raw material with elemental chlorine free bleaching and total chlorine free bleaching sequences for papermaking can be a valuable approach for reducing pollutants generation, utilization of waste biomass and fulfillment of fibrous raw material requirement for paper industry. [ABSTRACT FROM AUTHOR]

It is imperative to solve the problem of the electrolytic efficiency of chlorine evolution in extremely dilute chlorine-containing solutions for electrochemical advanced oxidation processes, electrochemical antifouling and chlorine-containing disinfectant preparation. In this paper, an IrO2–Ta2O5 electrode is modified using SnOx, and the activity and selectivity of the chlorine evolution reaction (CER) are successfully improved. The modification of SnOx changes the electronic structure of IrO2–Ta2O5, thus affecting the electrochemical reaction process and mechanism. Compared with the CER activity of the IrO2–Ta2O5 electrode, the CER activity of the SnOx@IrO2–Ta2O5 electrode is increased, whereas the OER activity is decreased. At a current density of 50 mA cm−2, the potential difference between the CER and OER of the SnOx@IrO2–Ta2O5-3 electrode is 254 mV, which is 89 mV higher than that of the IrO2–Ta2O5 electrode. This proves that the selectivity of the CER at the SnOx@IrO2–Ta2O5 electrode has been improved. Due to the low concentration of chloride ions, the current efficiency of the IrO2–Ta2O5 electrode is only 10.7%. The current efficiency of the SnOx@IrO2–Ta2O5-1(2,3) electrode increases to 23.6%, 36.7% and 49.6%, respectively. For the IrO2–Ta2O5 electrode, its rate-determining step (RDS) is the second electron transfer. However, for the SnOx@IrO2–Ta2O5-3 electrode, its RDS is electrochemical desorption. It can be inferred that the modification of SnOx can accelerate the electrochemical desorption of adsorbed Cl. In addition, the application of the SnOx@IrO2–Ta2O5 electrode in the preparation of AEW is investigated. The HClO content in AEW2 (prepared using the SnOx@IrO2–Ta2O5-3 electrode) is 1.85 mmol L−1, which is 4.6 times of that in AEW1 (prepared using the IrO2–Ta2O5 electrode). [ABSTRACT FROM AUTHOR]

Long-term immobilization ratios of strontium (Sr2+) and cesium (Cs+) in paper sludge ash-based geopolymer (PS-GP) were investigated in one year. PS-GP paste specimens were prepared in the conditions of 20 °C and 100% R.H., using two kinds of paper sludge ash (PS-ash). Two kinds of alkaline solution were used in the PS-GP as activator. One was prepared by diluting aqueous Na-disilicate (water glass) with seawater. Another was a mixture of this solution and caustic soda of 10 M concentration. When seawater was mixed into the alkaline solution, unstable fixations of Sr2+ and Cs+ were greatly improved, resulting stable and high immobilization ratios at any age up to one year, no matter what kind of PS-ash and alkaline solution were used. Element maps obtained by EPMA exhibited nearly even distribution of Cs+. However Sr2+ was biased, making domains so firmly related to Ca2+ presence. The mechanism that seawater stabilizes immobilization of Sr2+ and Cs+ was discussed in this study, but still needs to further investigation. Chemical composition analyses of PS-GP were also conducted by SEM-EDS. Two categories of GP matrix were clearly observed, so called N-A-S-H and C-A-S-H gels, respectively. By plotting in ternary diagrams of SiO2-(CaO + Na2O)-Al2O3 and Al2O3-CaO-Na2O, compositional trends were discussed in view of 'plagioclase gels' newly found in this study. As a result, it is suggested that the N-A-S-H and C-A-S-H gels should be strictly called Na-rich N-C-A-S-H and Ca-rich N-C-A-S-H gels, respectively. [ABSTRACT FROM AUTHOR]

Why Hydrogen. Nowadays, the energy industry and research laboratories are heavily working on developing ideas and methods to reduce and/or eliminate the carbon dioxide emission to control the problem of global warming. The solution relies on finding alternative green energy resources to reduce the world's dependence on conventional fossil hydrocarbon energy. Green hydrogen gas from water stands on the top of the alternative resources since it does not produce carbon dioxide when burned and in return does not add to global warming. Since seawater is the largest resource on earth, this makes the hydrogen production from seawater the most economically attractive solution. It is very important to avoid using fresh water as a source of hydrogen energy due to the dependence of all living creatures, humans, animals, plants, etc., on such very limited resources. In this paper, the applications of the proposed novel solution of green hydrogen production directly from seawater relies on solving one of the major problems, electrode corrosion. Generating Hydrogen. The direct method to produce green hydrogen from seawater is the electrolysis technique. This technique requires a direct current power supply for the positive and the negative electrodes. The outcome of the electrolysis is decomposing the saltwater to its positively charged hydrogen and sodium ions at the negative electrode and its negatively charged oxygen and chlorine ions at the positive electrode. The Real Challenge. Traditionally in the electrolysis analysis of water, both electrodes are made of metals. At the positive electrode, both the oxygen and the chlorine cause a high rate of corrosion to that electrode. This results in the interruption of the electrolysis process, bad water condition due to the corrosion deposits, and cost burden due to the need to periodically replace the corroded electrodes and/or use high-cost corrosion-resistant alloys. The Novel Solution. A low-cost but powerful solution to the corrosion problem is introduced, tested, and experimentally proved. The novelty of the solution relies on replacing the classic special high-cost metallic positive electrode with a nonmetallic, no-cost, one. The nonmetallic electrode is made of surface rock portions that have high porosity and pore volume and high permeability and pore connectivity and is saturated with saline water. Surface rocks with the above properties exhibit very low resistivity and hence conduct electricity like metallic electrodes. The voltage and the current conducted by such electrode are controlled by the electrode geometry, connectivity, and physical properties. Results and Discussions. Multiple experiments using the proposed nonmetallic high-porosity and high-permeability positive electrode are conducted and presented in this paper. The experimental work is based on testing multiple rock electrodes with different rock properties, sizes, and connectivity in comparison to the metallic ones. The comparison showed that the novel solution solved the corrosion challenges of the metallic electrodes with excellent efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a life cycle assessment (LCA) of bleached eucalyptus kraft pulp production in Brazil. The entire production system was investigated, starting with forestry and ending with bleached pulp at the gate of the pulp mill. Alternative bleaching sequences were compared for three different scenarios using somewhat different elemental chlorine-free (ECF) sequences: Dhot(EPO)DD, Dhot(EPO)DP, and aZeDP. The main difference between the scenarios investigated was the magnitude of the carbon footprint contribution from bleaching. For the base case and chemical island scenarios (both reflecting Brazilian conditions), the contribution was 15%-18% of the total carbon footprint. For the ecoinvent scenario, the corresponding share was 34%-41%. The ecoinvent scenario represents generic LCA data for bleaching chemicals. Ecoinvent is a public database commonly included in commercial LCA software. For each scenario, the alternative bleaching sequences studied resulted in similar carbon footprints of the bleached pulp. A comparison of the data from the different scenarios showed a large range of carbon footprints for the chemicals used for pulp bleaching. It is crucial to select data sets that are relevant in terms of geography and technology. The most dominant contributors to the carbon footprint of the unbleached pulp were forestry and pulp production. Although the focus has been on carbon footprints, the contributions to other environmental effects commonly included in LCAs were also assessed and only minor differences between the alternative bleaching sequences were found. Application: This study shows how LCA can be applied to assess environmental impacts in the pulp and paper industry. Knowledge about the magnitude of the contributions made by the different parts of the value chain is useful as a basis for further improvements to reduce the environmental footprint. [ABSTRACT FROM AUTHOR]

PVC items (38% carbon atoms w/w) are environmentally friendly as, unlike polyolefins (86% carbon atoms w/w), they are mainly based on chlorine, one of the most abundant elements on Earth and, so, less based on fossil resources. However, in the eco-design context, articles' durability plays a crucial role, contributing to the enhancement of their sustainability. In this framework, the research on additives capable of increasing the weatherability of outdoor articles is essential. The theory section of the paper reviews the mechanisms of weathering that lead to PVC degradation and undermine the durability of items such as window frames or roller shutters. The weathering of PVC items is a complex phenomenon, involving photo-chemical and secondary chemical reactions, that yields the formation of conjugated polyene sequences underskin in the absence of oxygen and carbonyls in the surface. Here, the chain scission of the polymer backbone occurs, bringing about the disintegration of the surface of the item and causing the typical discoloration called chalking, especially evident in dark-colored articles. In the experimental section of the paper, the effect of different acid scavengers on item weathering has been studied using a natural outdoor and two accelerated exposures with xenon-arc and Q-UV testing devices. Results confirm that some acid scavengers are efficient in preventing chalking, but some are ineffective or even detrimental. Thus, the PVC formulations of durable articles upon weathering still depend on a complex choice of the appropriate ingredients, and several outdoor and indoor accelerated-weathering tests are needed to predict the articles' lifetime. [ABSTRACT FROM AUTHOR]

Disinfection efficiency and disinfection byproduct (DBP) formation are two important aspects deserving careful consideration when evaluating different disinfection protocols. However, most of the previous studies on the selection of disinfection methods by comparing DBP formation were carried out under the same initial/residual dose and contact time of different disinfectants, and such a practice may cause overdose or underdose of a certain disinfectant, leading to the inaccurate evaluation of disinfection. In this study, a comprehensive and quantitative comparison of chlorine (Cl 2 ) and chlorine dioxide (ClO 2 ) disinfection was conducted with regard to their DBP formation under equal disinfection efficiency. The microbial inactivation models as well as the Cl 2 and ClO 2 demand models were developed. On such basis, the integral CT (ICT) values were determined and used as a bridge to connect disinfection efficiency and DBP formation. For 3-log 10 and 4-log 10 reductions of Pseudomonas aeruginosa, ClO 2 had 1.5 and 5.8 times higher inactivation ability than Cl 2 , respectively. In the premise of equal disinfection efficiency (i.e., the ICT ratios of Cl 2 to ClO 2 = 1.5 and 5.8), the levels of total organic chlorine, total organic bromine, and total organic halogen formed in the Cl 2 disinfection were significantly higher than those formed in the ClO 2 disinfection. Among the 35 target aliphatic DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs) were the dominant species formed in both Cl 2 and ClO 2 disinfection. The total THM levels formed in Cl 2 disinfection were 14.6 and 30.3 times higher than those in ClO 2 disinfection, respectively. The total HAA levels formed in Cl 2 disinfection were 3.5 and 5.4 times higher than those in ClO 2 disinfection, respectively. Formation of the target 48 aromatic DBPs was much favored in Cl 2 disinfection than that in ClO 2 disinfection, and the formation levels was dominated by contact time. This study demonstrated that ClO 2 had significant advantages over Cl 2 , especially at higher microorganism inactivation and lower DBP formation requirements., 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.)

Chlorination on microplastic (MP) biofilms was comprehensively investigated with respect to disinfection efficiency, morphology, and core microbiome. The experiments were performed under various conditions: i) MP particles; polypropylene (PP) and polystyrene (PS), ii) MP biofilms; Escherichia coli for single-species and river water microorganisms for multiple-species, iii) different chlorine concentrations, and iv) different chlorine exposure periods. As a result, chlorination effectively inactivated the MP biofilm microorganisms. The disinfection efficiency increased with increasing the free chlorination concentration and exposure periods for both single- and multiple-species MP biofilms. The multiple-species MP biofilms were inactivated 1.3-6.0 times less than single-species MP biofilms. In addition, the PP-MP biofilms were more vulnerable to chlorination than the PS-MP biofilms. Morphology analysis verified that chlorination detached most MP biofilms, while a small part still remained. Interestingly, chlorination strongly changed the biofilm microbiome on MPs; the relative abundance of some microbes increased after the chlorination, suggesting they could be regarded as chlorine-resistant bacteria. Some potential pathogens were also remained on the MP particles after the chlorination. Notably, chlorination was effective in inactivating the MP biofilms. Further research should be performed to evaluate the impacts of residual MP biofilms on the environment., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kyungjin Cho reports financial support was provided by National Research Foundation of Korea (NRF). If there are other authors, they 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 The Authors. Published by Elsevier B.V. All rights reserved.)

The study investigates the effect of the presence of a chlorine atom in the 2'-hydroxychalcone molecule on its interaction with model lipid membranes, in order to discern its potential pharmacological activity. Five chlorine derivatives of 2'-hydroxychalcone were synthesized and evaluated against liposomes composed of POPC and enriched with cationic (DOTAP) or anionic (POPG) lipids. The physicochemical properties of the compounds were initially simulated using SwissAdame software, revealing high lipophilicity (ilogP values: 2.79-2.90). The dynamic light scattering analysis of liposomes showed that chloro chalcones induce minor changes in the diameter of liposomes of different surface charges. Fluorescence quenching assays with a TMA-DPH probe demonstrated the strong ability of the compounds to interact with the lipid bilayer, with varying quenching capacities based on chlorine atom position. FTIR studies indicated alterations in carbonyl, phosphate, and choline groups, suggesting a transition area localization rather than deep penetration into the hydrocarbon chains. Additionally, dipole potential reduction was observed in POPC and POPC-POPG membranes, particularly pronounced by derivatives with a chlorine atom in the B ring. Antibacterial and antibiofilm assays revealed enhanced activity of derivatives with a chlorine atom compared to 2'-hydroxychalcone, especially against Gram-positive bacteria. The MIC and MBIC 50 values showed increased efficacy in the presence of chlorine with 3'-5'-dichloro-2'-hydroxychalcone demonstrating optimal antimicrobial and antibiofilm activity. Furthermore, antiproliferative assays against breast cancer cell lines indicated higher activity of B-ring chlorine derivatives, particularly against MDA-MB-231 cells. In general, the presence of a chlorine atom in 2'-hydroxychalcone improves its pharmacological potential, with derivatives showing improved antimicrobial, antibiofilm, and antiproliferative activities, especially against aggressive breast cancer cell lines. These findings underscore the importance of molecular structure in modulating biological activity and highlight chalcones with a chlorine as promising candidates for further drug development studies., 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 B.V. All rights reserved.)

As global effects of water scarcity raise concerns and environmental regulations evolve, contemporary wastewater treatment plants (WWTPs) face the challenge of effectively removing a diverse range of contaminants of emerging concern (CECs) from municipal effluents. This study focuses on the assessment of advanced oxidation processes (AOPs), specifically UV-C/H 2 O 2 and UV-C/Chlorine, for the removal of 14 target CECs in municipal secondary effluent (MSE, spiked with 10 μg L -1 of each CEC) or in the subsequent MSE nanofiltration retentate (NF R , no spiking). Phototreatments were carried out in continuous mode operation, with a hydraulic retention time of 3.4 min, using a tube-in-tube membrane photoreactor. For both wastewater matrices, UV-C photolysis (3.3 kJ L -1 ) exhibited high efficacy in removing CECs susceptible to photolysis, although lower treatment performance was observed for NF R . In MSE, adding 10 mg L -1 of H 2 O 2 or Cl 2 enhanced treatment efficiency, with UV-C/H 2 O 2 outperforming UV-C/Chlorine. Both UV-C/AOPs eliminated the chronic toxicity of MSE toward Chlorella vulgaris. In the NF R , not only was the degradation of target CECs diminished, but chronic toxicity to C. vulgaris persisted after both UV-C/AOPs, with UV-C/Chlorine increasing toxicity due to potential toxic by-products. Nanofiltration permeate (NF P ) exhibited low CECs and microbial content. A single chlorine addition effectively controlled Escherichia coli regrowth for 3 days, proving NF P potential for safe reuse in crop irrigation (<1 CFU/100 mL for E. coli; <1 mg L -1 for free chlorine). These findings provide valuable insights into the applications and limitations of UV-C/H 2 O 2 and UV-C/Chlorine for distinct wastewater treatment scenarios., 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 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Controlling the dissemination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) is a global concern. While commonly used chlorine disinfectants can damage or even kill ARB, dissolved oxygen (DO) may affect the formation of reactive chlorine species. This leads to the hypothesis that DO may play roles in mediating the effectiveness of chlorine disinfection for antibiotic resistance. To this end, this study investigated the impacts of DO on the efficiency of chlorine disinfection for antibiotic resistance. The results revealed that DO could increase the inactivation efficiency of ARB under chloramine and free chlorine exposure at practically relevant concentrations. Reactive species induced by DO, including H 2 O 2 , O 2 - ) was enhanced with increasing dosage of free chlorine or chloramine under aerobic conditions. DO facilitated the fragmentation of plasmids, contributing to the degradation of extracellular ARGs under exposure to chlorine disinfectants. The findings suggested that DO facilitates disinfection efficiency for antibiotic resistance in water treatment systems.TEM ) was enhanced with increasing dosage of free chlorine or chloramine under aerobic conditions. DO facilitated the fragmentation of plasmids, contributing to the degradation of extracellular ARGs under exposure to chlorine disinfectants. The findings suggested that DO facilitates disinfection efficiency for antibiotic resistance in water treatment systems., 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. Published by Elsevier B.V.)

There has been numerous research on the uses of treated wastewater that needs chlorine disinfection, but none have looked at the impacts of injecting nanobubbles (NBs) on the decomposition of residual chlorine. Gas NB injection in treated wastewater improves its properties. The kinetics of disinfectant decay could be impacted by changes in treated wastewater properties. This paper studies the effect of various NB injections on the residual chlorine decay of secondary treated wastewater (STWW). It also outlines the empirical equations that were developed to represent these impacts. The results show that each type of NBs in treated wastewater had a distinct initial chlorine concentration. The outcomes demonstrated a clear impact on the decrease of the needed chlorine quantity and the reduction of chlorine decay rate when utilizing NB injection for the STWW. As a result, the residual chlorine will remain for a longer time and will resist any microbiological growth under the application of NBs on treated wastewater. Moreover, NBs in secondary treated effluent reduce chlorine usage, lowering wastewater disinfection costs., Competing Interests: The authors declare there is no conflict., (© 2024 The Authors This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

Shaerhu (SEH) coal is abundant in Xinjiang, China. The utilization of SEH suffers from severe ash deposition, slagging, and fouling problems due to its high-chlorine-alkaline characteristics. The co-combustion of high-alkaline coal and other type coals containing high Si/Al oxides has been proven to be a simple and effective method that will alleviate ash-related problems, but the risk of heavy metals (HMs) contamination in this process is nonnegligible. Hence, the volatilization rates and chemical speciation of Pb, Cu, and Zn in co-combusting SEH and a high Si/Al oxides coal, i.e., Yuanbaoshan (YBS) coal were investigated in this study. The results showed that the addition of SEH increased the volatilization rates of Pb, Cu, and Zn during the co-combustion at 800°C from 23.70%, 23.97%, and 34.98% to 82.31%, 30.01%, and 44.03%, respectively, and promoted the extractable state of Cu and Zn. In addition, the interaction between SEH and YBS inhibited the formation of the Pb residue state. SEM-EDS mapping results showed that compared to Zn and Cu, the signal intensity of Pb was extremely weak in regions where some of the Si and Al signal distributions overlap. The DFT results indicated that the O atoms of the metakaolin (Al 2 O 3 ⋅2SiO 2 ) (001) surface were better bound to the Zn and Cu than Pb atoms after adsorption of the chlorinated HMs. These results contribute to a better understanding of the effects of high-alkaline coal blending combustion on Pb, Cu, and Zn migration and transformation., Competing Interests: Declaration of Competing Interests 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 © 2023. Published by Elsevier B.V.)

Chlorine is commonly used by the fresh produce industry to sanitize water and minimize pathogen cross-contamination during handling. The pH of chlorinated water is often reduced to values of pH 6-7, most commonly with citric acid to stabilize the active antimicrobial, hypochlorous acid (a form of free chlorine). Previous studies have demonstrated that citric acid reacts with chlorine to form trichloromethane, a major chlorine by-product in water and a potential human carcinogen. However, it is unclear if other pH control agents could be used in the place of citric acid to minimize the formation of trichloromethane. The objective of the present study was to determine the reactivity of organic and inorganic pH control agents, with chlorine, to generate trichloromethane. Free chlorine (∼100 mg/L) was mixed with 10 mM of each of twelve organic acids and two inorganic pH control agents (i.e., sodium acid sulfate and phosphoric acid) to effect a pH level of 6.5. Free chlorine and trichloromethane levels were measured over 3 h at 3 and 22°C. Results demonstrated that ascorbic acid, dehydroascorbic acid, citric acid, and malic acid rapidly depleted free chlorine concentrations at both 22°C and 3°C, while tartaric acid and lactic acid decreased chlorine concentrations more slowly. Other pH control agents did not significantly reduce free chlorine either at 22 or 3°C. Citric acid led to the generation of significantly higher concentrations of trichloromethane than did other acids. Chloroacetone was also found in chlorinated water in the presence of citric acid and ascorbic acid. Taking buffering capacity and pKa values into account, phosphoric acid and some organic acids may be used to replace citric acid as pH control agents in chlorinated water for washing fresh produce, to stabilize free chlorine level and reduce the generation of trichloromethane., 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., (Published by Elsevier Inc.)

Amino acids (AAs) account for about 15-35% of dissolved organic nitrogen (DON), and are known as the important precursors of nitrogenous disinfection by-products (N-DBPs). Determining the formation potential (FP) of AAs to DBPs is used to reveal the key precursors of DBPs for further control, while the ideal method for N-DBPs FP of AAs during chlorination is not revealed. In this study, the ideal FP test models for five classes of priority DBPs during chlorination of four representative AAs (accounted for about 35% of total AAs) were analyzed. For haloaldehydes (HALs), haloketones (HKs), haloacetonitriles (HANs), haloacetamides (HAMs), and halonitromethanes (HNMs), their FPs during chlorination of four AAs were 0.1-13.0, 0.01-1.1, 0.1-104, not detectable (nd)-173, and nd-0.4 μg/mg, respectively. The FPs of priority DBPs had significant deviations between different FP test models and different tested AAs. For HALs, the model, whose chlorine dosage was determined by 15 × molar concentration of AAs [Cl (mM) = 15 × M](named: model II), was the ideal model. For HKs, model II was also the ideal FP test model for AAs with ≤3 carbons, while for AAs with 4 carbons, the model, whose chlorine dosage was determined by keeping the residual chlorine at 1 ± 0.2 mg/L after 24 h of reaction (named: model 4), was the ideal model. For HANs and HNMs, model 4 was the ideal FP test model for most of the studied AAs. The performance of HAMs during chlorination of amino acids was totally different from other P-DBPs, and model 3 was recommended to be the ideal model, in which chlorine dosage was determined by 3 × mass concentration of AAs [Cl (mg/L) = X × DOC]. This study is a reference that helps researchers select an ideal model for N-DBPs FP study of AAs., 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.)

Microbial community biofilm exists in the household drinking water system and would pose threat to water quality. This paper explored biofilm formation and chlorination resistance of ten dual-species biofilms in three typical household pipes (stainless steel (SS), polypropylene random (PPR), and copper), and investigated the role of interspecific interaction. Biofilm biomass was lowest in copper pipes and highest in PPR pipes. A synergistic or neutralistic relationship between bacteria was evident in most biofilms formed in SS pipes, whereas four groups displayed a competitive relationship in biofilms formed in copper pipe. Chlorine resistance of biofilms was better in SS pipes and worse in copper pipes. It may be helped by interspecific relationships, but was more dependent on bacteria and resistance mechanisms such as more stable extracellular polymeric substance. The corrosion sites may also protect bacteria from chlorination. The findings provide useful insights for microbial control strategies in household drinking water systems., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The coexistence of free chlorine and bromide under sunlight irradiation (sunlight/FC with Br - ) is unavoidable in outdoor seawater swimming pools, and the formation of brominated disinfection byproducts could act more harmful than chlorinated disinfection byproducts. In this study, benzotriazole was selected as a model compound to investigate the degradation rate and the subsequent formation of disinfection byproducts via sunlight/FC with Br - process. The rate constants for the degradation of benzotriazole under pseudo first order conditions in sunlight/FC with Br - and sunlight/FC are 2.3 ± 0.07 × 10 -1  min -1 and 6.0 ± 0.7 × 10 -2  min -1 , respectively. The enhanced degradation of benzotriazole can be ascribed to the generation of HO•, bromine species, and reactive halogen species (RHS) during sunlight/FC with Br - . Despite the fact that sunlight/FC with Br - process enhanced benzotriazole degradation, the reaction results in increasing tribromomethane (TBM) formation. A high concentration (37.8 μg/L) of TBM was detected in the sunlight/FC with Br - , which was due to the reaction of RHS. The degradation of benzotriazole was notably influenced by the pH value (pH 4 - 11), the concentration of bromide (0 - 2 mM), and free chlorine (1 - 6 mg/L). Furthermore, the concentration of TBM increased when the free chlorine concentrations increased, implying the formation potential of harmful TBM in chlorinated seawater swimming pools., 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.)

Maintaining residual chlorine levels in a water distribution networks is a challenging task; especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very im portant to understand chlorine kinetics in bulk water. Recent studies suggested that chlorine decay rate depends on initial chlorine levels and type of organic and inorganic matter present in water, indicating that first order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed two reactant model (2R) to estimate the fast and slow reacting components in surface water and groundwater. We carried out bench scale test for surface and groundwater at initial chlorine level of 1, 2 and 5mgL??1. We used decay datasets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay dataset with varying initial chlorine concentration (ICC). This study came up with three important findings (a) the ratio of slow to fast reacting components in groundwater was thirty times greater than that of the surface water, (b) 2R model can accurately predict chlorine decay in surface water, 98% of the variance in the chlorine decay test was explained by the model and (c) in case groundwater, 2R model prediction accuracy reduced with the decrease in ICC levels, only 87% variance in data was explained by the model. This could be attributed to high slow to fast reactant ratio in 20 groundwater. [ABSTRACT FROM AUTHOR]

This Special Issue includes manuscripts on mechanistic understanding, development, and implementation of advanced oxidation processes (AOPs) for the removal of contaminants of emerging concern in water and wastewater treatment. The main goal was successfully achieved under the joint effort of authors, anonymous reviewers, and editorial managers. Totally, one review and 15 research papers are included in the Special Issue. These are mainly focused on catalyst synthesis, reactor design, treatment performance, kinetic modeling, reaction mechanisms, and by-product formation during electrochemical, photocatalytic, plasma, persulfate, chlorine, ozone-based, and Fenton-related AOPs at different scales. This Special Issue received attention from researchers from different parts of the world such as Argentina, Brazil, Canada, China, Germany, India, Mexico, and the USA. The guest editors are happy to see that all papers presented are innovative and meaningful, and hope that this Special Issue can promote mechanistic understanding and engineering applications of AOPs for the removal of contaminants of emerging concern in water. [ABSTRACT FROM AUTHOR]

At present, conjugated thermolysis of metal-containing monomers is widely used as single-source precursors to obtain new metal- and metal oxide-containing nanocomposites. In this study, a detailed analysis of the main stages of conjugated thermolysis of silver itaconate was carried out. The obtained nanocomposites containing silver nanoparticles are evenly distributed in a stabilizing carbon matrix. The structural characteristics and properties of the resulting nanomaterials were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). We have developed a method of test analysis of chlorides using paper modified with the obtained silver-containing nanocomposites. The analysis technique is based on the in situ conversion of chlorides to molecular chlorine, its dynamic release, and colorimetric detection using NP-modified paper test strips. A simple installation device is described that allows this combination to be realized. The proposed approach seems promising for nanoparticle-based determinations of other analytes that can be converted into volatile derivatives. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of alkaline kraft elemental chlorine-free bleaching wastewater in two mesophilic, lab-scale upflow anaerobic sludge bed reactors resulted in significantly higher biogas production (250 ± 50 vs. 120 ± 30 NmL g) and reduction of filtered total organic carbon (fTOC) (60 ± 5 vs. 43 ± 6%) for wastewater from processing of hardwood (HW) compared with softwood (SW). In all cases, the gas production was likely underestimated due to poor gas separation in the reactors. Despite changes in wastewater characteristics, a stable anaerobic process was maintained with hydraulic retention times (HRTs) between 7 and 14 h. Lowering the HRT (from 13.5 to 8.5 h) did not significantly affect the process, and the stable performance at 8.5 h leaves room for further decreases in HRT. The results show that this type of wastewater is suitable for a full-scale implementation, but the difference in methane potential between SW and HW is important to consider both regarding process dimensioning and biogas yield optimization. [ABSTRACT FROM AUTHOR]

A Hypo helmet is a fabric hood soaked with an aqueous solution of two sodium salts for the detoxication of chlorine that was developed during the First World War. Herein, we report on a lecture, developed for non-chemistry majors that used the Hypo helmet to highlight the physical and chemical properties of chlorine. The lecture consisted of the following three components: (1) a brief introduction to the First World War (the Chemists' War), (2) video demonstrations of the generation of chlorine by mixing bleaching powder and hydrochloric acid and the detoxication of chlorine using a dummy Hypo helmet, and (3) students' written impressions of the lecture. The students' written impressions revealed two things: the lecture on chlorine and the Hypo helmet was well received, and most of the students (71 %, N = 82) did not know that chlorine was used as a poisonous gas during the First World War. [ABSTRACT FROM AUTHOR]

Aim: To monitor chlorine consumption from nonagitated aqueous sodium hypochlorite (NaOCl) solutions in human root canals using a recently developed assay, which can determine the order of magnitude of available chlorine in small volumes of liquid., Methodology: The root canals of 80 extracted single-rooted human teeth were instrumented to ProTaper Universal F4 and irrigated using 1% NaOCl. Subsequently, canals were irrigated with copious amounts of deionized water to rinse out the residual chlorine. Subsequently, the teeth were sealed externally and placed in a water bath of 37 °C. Root canals were filled with NaOCl of 1%, 2.75%, 5.5%, or distilled water for 1, 10, 100 or 1000 min (n = 5 teeth per solution and time). Consumption of chlorine was measured using paper points pre-impregnated with 15% potassium iodide. Colour change of the paper points was determined photo-electronically, assessing their red value after absorbing solutions from root canals. Measurements were compared to a standard series of NaOCl down to 0.001% (n = 5 paper points per concentration)., Results: Red values of the paper points inserted into the root canal were affected by initial NaOCl concentration and time (two-way anova, P < 0.05). If NaOCl concentrations above 0.1% are considered to be clinically relevant, then 5.5% NaOCl retained its activity in the root canal for more than 100 min, whereas 1% NaOCl lost its activity between 10 and 100 min., Conclusions: Nonagitated NaOCl solutions can remain biologically active in human root canals for extended time periods., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Wastewater polluted by organics can be treated by using electro-generated active chlorine, even if this promising route presents some important drawbacks such as the production of chlorinated by-products. Here, for the first time, this process was studied in a microfluidic electrochemical reactor with a very small inter-electrode distance (145 μm) using a water solution of NaCl and phenol and a BDD anode. The potential production of chloroacetic acids, chlorophenols, carboxylic acids, chlorate and perchlorate was carefully evaluated. It was shown, for the first time, up to our knowledge, that the use of the microfluidic device allows to perform the treatment under a continuous mode and to achieve higher current efficiencies and a lower generation of some important by-products such as chlorate and perchlorate. As an example, the use of the microfluidic apparatus equipped with an Ag cathode allowed to achieve a high removal of total organic carbon (about 76%) coupled with a current efficiency of 17% and the production of a small amount of chlorate (about 30 ppm) and no perchlorate. The effect of many parameters (namely, flow rate, current density and nature of cathode) was also investigated., 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 The Authors. Published by Elsevier Ltd.. All rights reserved.)