Cl2 Gas Research Articles

Hierarchically Porous Graphene Aerogels with Abundant Oxygenated Groups for High-Energy-Density Surpercapacitors

A hierarchically porous graphene aerogel (HP-GA) with abundant oxygenated groups and hand-tearing bread-like macromorphology is achieved by a sacrificial MnO2 template approach. Oxygenated groups on graphene sheets improve the wettability of HP-GA to an aqueous electrolyte and contribute to pseudocapacitance. The chlorine (Cl2) gas as a result of the reaction of MnO2 and HCl is responsible for the formation of the hierarchically porous microstructure and hand-tearing bread-like macromorphology, ensuring a large electrolyte accessible surface area within the electrodes. When used as the active electrode material in supercapacitors, HP-GA exhibits a large specific capacitance of 284 F g–1 at 1 A g–1 and ultrahigh energy density of 10 Wh kg–1 at 250 W kg–1 in an aqueous electrolyte. This work provides a versitile, simple, and easy to control way to alter the microstructure and macromorphology of graphene-based areogels that have promising applications in many areas, including adsorption, energy storage, heat insulation, acoustical insulation, and intelligent sensing system.

Effect of residual chlorine on fluorescence emission of Dy3+ doped chalcogenide glasses with low gallium content

AbstractChlorine or chlorides are usually used as a dehydrating agent for removing the O‐H or S(Se)‐H in the preparation of high‐purity chalcogenide glasses. However, the residual chlorine in some rare‐earth ions doped chalcogenide glasses was found to have a great negative impact on fluorescence emission. In this work, the effect of residual chlorine on the fluorescence emission of Dy3+ ions in serial (Ge)GaAsSbS glasses was studied quantitatively, and the reasons were discussed. Cl2 gas and SbCl3 were used as the source of chlorine and their residual contents were controlled by the post‐distillation process and added content, respectively. The results can give some suggestions for how to eliminate the negative effects of chlorine and improve the glass’ optical gain properties.

Improved leaching of Cu, Sn, Pb, Zn, and Al from waste printed circuit boards by electro-generated Cl2 in HCl solution

This paper investigated the improved leaching of Cu, Sn, Pb, Zn, and Al from waste printed circuit boards (WPCBs) by electro-generated Cl2 in HCl solution through multiple leaching cells in series, double intake pipes, and bubble stone for leaching. The leaching agents in the leaching cell include Cl2(aq), HCl, HClO, and Cl3-. The leaching rate and leaching speed of Zn, Sn, Al, and Pb exceeded that of Cu. Leaching time and HCl concentration have a strong impact on the dissolution of Cu, whereas the effect of the electrolytic current and the leaching temperature is comparably weak. The series of leaching cells improved the effective utilization of Cl2 and increased the treatment capacity of the WPCBs. Bubble stones significantly enhanced the efficiency and rate of leaching. Reduction of the size of the Cl2 gas bubbles improved the leaching kinetics. The leaching rate of Cu reached 87.22%, whereas the leaching rate of Zn, Sn, Al, and Pb exceeded 90% after 100 min. Our experimental data provide a reference for electrolytic leaching recovery of metals from WPCBs, and our method improves the metal leaching and electrolytic efficiency in practice.

Electrolytic Separation of Iodine from LiCl–KCl–LiBr–LiI Melt and Recovery of Iodine Gas with Copper

The separation and recovery of iodine from LiCl–KCl–LiBr–LiI melt was investigated at 723 K. Cyclic voltammograms at a glass-like carbon electrode showed that I2 gas generates at more negative potential compared with Cl2 and Br2 gases. Potentiostatic electrolysis for I2 gas generation was conducted at glassy carbon and Au electrodes, where the generated I2 gas was collected by a Cu mesh placed at the top of the cell. XRD confirmed that the Cu mesh changed to CuI. At a glass-like carbon electrode, recovery efficiencies of iodine were 64% and 97% at 3.2 V and 3.3 V vs. Li+/Li, respectively. The recovery efficiency at an Au electrode was 93%. However, a part of the Au electrode dissolved into the melt. Finally, a continuous recovery method was proposed, in which the generated I2 gas was recovered by several independently recoverable Cu meshes packed in a borosilicate gas outlet tube.

Differential modulation of lung aquaporins among other pathophysiological markers in acute (Cl2 gas) and chronic (carbon nanoparticles, cigarette smoke) respiratory toxicity mouse models.

Inhaled toxic chemicals and particulates are known to disrupt lung homeostasis causing pulmonary toxicity and tissue injury. However, biomarkers of such exposures and their underlying mechanisms are poorly understood, especially for emerging toxicants such as engineered nanoparticles and chemical threat agents such as chlorine gas (Cl2). Aquaporins (AQPs), commonly referred to as water channels, are known to play roles in lung homeostasis and pathophysiology. However, little is known on their regulation in toxicant-induced lung injuries. Here, we compared four lung toxicity models namely, acute chemical exposure (Cl2)-, chronic particulate exposure (carbon nanotubes/CNT)-, chronic chemical exposure (cigarette smoke extract/CSE)-, and a chronic co-exposure (CNT + CSE)- model, for modulation of lung aquaporins (AQPs 1, 3, 4, and 5) in relation to other pathophysiological endpoints. These included markers of compromised state of lung mucosal lining [mucin 5b (MUC5B) and surfactant protein A (SP-A)] and lung-blood barrier [protein content in bronchoalveolar lavage (BAL) fluid and, cell tight junction proteins occludin and zona-occludens]. The results showed toxicity model-specific regulation of AQPs measured in terms of mRNA abundance. A differential upregulation was observed for AQP1 in acute Cl2 exposure model (14.71-fold; p = 0.002) and AQP3 in chronic CNT exposure model (3.83-fold; p = 0.044). In contrast, AQP4 was downregulated in chronic CSE model whereas AQP5 showed no significant change in any of the models. SP-A and MUC5B expression showed a decreasing pattern across all toxicity models except the acute Cl2 toxicity model, which showed a highly significant upregulation of MUC5B (25.95-fold; p = 0.003). This was consistent with other significant pathophysiological changes observed in this acute model, particularly a compromised lung epithelial-endothelial barrier indicated by significantly increased protein infiltration and expression of tight junction proteins, and more severe histopathological (structural and immunological) changes. To our knowledge, this is the first report on lung AQPs as molecular targets of the study toxicants. The differentially regulated AQPs, AQP1 in acute Cl2 exposure versus AQP3 in chronic CNT nanoparticle exposure, in conjunction with the corresponding differentially impacted pathophysiological endpoints (particularly MUC5B) could potentially serve as predictive markers of toxicant type-specific pulmonary injury and as candidates for future investigation for clinical intervention.

Gas-Sensing Properties of B/N-Modified SnS2 Monolayer to Greenhouse Gases (NH3, Cl2, and C2H2).

The adsorption capacity of intrinsic SnS2 to NH3, Cl2 and C2H2 is very weak. However, non-metallic elements B and N have strong chemical activity, which can significantly improve the conductivity and gas sensitivity of SnS2. Based on density functional theory, SnS2 was modified with B and N atoms to analyze its adsorption mechanism and gas sensitivity for NH3, Cl2 and C2H2 gases. The optimal structure, adsorption energy, state density and frontier molecular orbital theory are analyzed, and the results are in good agreement with the experimental results. The results show that the adsorption of gas molecules is exothermic and spontaneous. Only the adsorption of NH3 and Cl2 on B-SnS2 belongs to chemical adsorption, whereas other gas adsorption systems belong to physical adsorption. Moderate adsorption distance, large adsorption energy, charge transfer and frontier molecular orbital analysis show that gas adsorption leads to the change of the conductivity of the modified SnS2 system. The adsorption capacity of B-SnS2 to these gases is Cl2 > NH3 > C2H2. The adsorption capacity of N-SnS2 is NH3 > C2H2 > Cl2. Therefore, according to different conductivity changes, B-SnS2 and N-SnS2 materials can be developed for greenhouse gas detection of gas sensors.

Adsorption of Greenhouse Decomposition Products on Ag2O-SnS2 and CuO-SnS2 Surfaces.

In this paper, based on density functional theory, the adsorption mechanism and gas sensitivity of Ag2O/CuO-modified SnS2 were analyzed. The results were analyzed according to the adsorption energy, total density of states, partial density of states, and frontier molecular orbital theory. The results show that the adsorption of all gas molecules is exothermic. NH3, Cl2, and C2H2 gases are chemisorbed on the modified SnS2 surfaces. After gas adsorption, the energy gap of the base changes by more than 10%, which fully shows that the conductivity changes greatly after gas adsorption, which can be reflected in the macroscopic resistance change. Ag2O–SnS2 is suitable as a gas sensor for NH3 gas sensors in terms of moderate adsorption distance, large adsorption energy, charge transfer, and frontier molecular orbital theory, while CuO–SnS2 is more suitable as a C2H2 gas sensor.

Effect of Pd-Sensitization on Poisonous Chlorine Gas Detection Ability of TiO2: Green Synthesis and Low-Temperature Operation.

Ganoderma lucidum mushroom-mediated green synthesis of nanocrystalline titanium dioxide (TiO2) is explored via a low-temperature (≤70 °C) wet chemical method. The role of Ganoderma lucidum mushroom extract in the reaction is to release the ganoderic acid molecules that tend to bind to the Ti4+ metal ions to form a titanium-ganoderic acid intermediate complex for obtaining TiO2 nanocrystallites (NCs), which is quite novel, considering the recent advances in fabricated gas sensing materials. The X-ray powder diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller measurements etc., are used to characterize the crystal structure, surface morphology, and surface area of as-synthesized TiO2 and Pd-TiO2 sensors, respectively. The chlorine (Cl2) gas sensing properties are investigated from a lower range of 5 ppm to a higher range of 400 ppm. In addition to excellent response–recovery time, good selectivity, constant repeatability, as well as chemical stability, the gas sensor efficiency of the as-synthesized Pd-TiO2 NC sensor is better (136% response at 150 °C operating temperature) than the TiO2 NC sensor (57% at 250 °C operating temperature) measured at 100 ppm (Cl2) gas concentration, suggesting that the green synthesized Pd-TiO2 sensor demonstrates efficient Cl2 gas sensing properties at low operating temperatures over pristine ones.

Effect of operating cell voltage on the NaCl poisoning mechanism in polymer electrolyte membrane fuel cells

The mechanism of NaCl poisoning in polymer electrolyte membrane fuel cells (PEMFCs) depends on the operating cell voltage. Both the Pt dissolution and the liberation of Cl2 and CO2 gases are monitored using an on-line mass spectrometer to differentiate between the different poisoning mechanisms. The changes in the particle size and composition of the catalyst are measured by high-resolution transmission electron microscopy and energy dispersive spectroscopy. At a cell voltage of 0.6 V the degradation of performance due to NaCl poisoning is primarily attributed to blockage of the active sites of the catalyst by the adsorption of Cl−. This reduced performance can be fully restored by removing Cl− in the form of Cl2 while slowing down the carbon corrosion reaction. However, NaCl poisoning at a high cell voltage of 0.9 V results in Cl−-induced dissolution of the Pt catalyst, which prevents performance recovery. Thus, it has been demonstrated that the NaCl poisoning mechanism and the reversibility of the performance loss depends largely on the operating cell voltage of the PEMFC.

Chlorine inhalation toxicology‐on‐a‐chip

Accidental or environmental exposures to chlorine (Cl2 ) gas represent a major health threat. In particular, inhalation toxicology of Cl2 is an area of active research that focuses on investigating the deleterious effects of Cl2 on the human respiratory system and developing effective countermeasures to mitigate the risk of Cl2 -induced lung injury. While traditional cell culture models have gained widespread use as a simple and convenient research tool for in vitro investigation of Cl2 toxicity, they have limited capacity to recapitulate the complexity of native human lung tissues and thus largely fail to generate accurate predictions on pulmonary responses to Cl2 . Here we present two distinct microengineered biomimetic models that reconstruct the small airway and alveolar regions of the human lung for experimental studies of respiratory toxicity of Cl2 in the distal lung, which remains an outstanding question in inhalation toxicology of Cl2 . Our microengineered small airway model is composed of two microfabricated 3D chambers separated by a semipermeable membrane. The design of this microdevice makes it possible to mimic tissue compartmentalization in native airways by permitting long-term co-culture of primary human small airway epithelial cells, primary human pulmonary microvascular endothelial cells, and lung fibroblasts in a physiological 3D microenvironment to engineer fully differentiated airway epithelium directly exposed to air and supported by vascularized, perfusable 3D stromal tissues. The alveolar model, which is constructed in the same device, uses primary human type II pneumocytes harvested from iPSC-derived human alveolar organoids, some of which are transdifferentiated into type I alveolar epithelial cells during the course of controlled microfluidic culture in our device. In this study, these models were capable of producing human lung tissues that exhibited differentiated phenotype and functional capacity that could be maintained for extended periods (over 1 month). Notably, our data revealed the potential of the underlying pulmonary vasculature to accelerate and promote differentiation and maturation of lung epithelial cells during air-liquid interface culture. Using the lung-on-a-chip systems in conjunction with an in-house Cl2 exposure system, we conducted a preliminary study in which the devices were exposed to various concentrations of Cl2 gas (10, 50, 100 and 300 ppm) for 15 min. Our preliminary data showed the deleterious potential of Cl2 to induce acute injury of both small airway and alveolar tissues in a dose-dependent manner. Studies are underway for more extensive screening of Cl2 toxicity and in-depth analysis of lung injury in our models at the molecular, cellular, and tissue levels. We believe that the microengineered systems developed in this work represent an important advance in our ability to model acute respiratory responses to toxic gases and may provide a potentially powerful in vitro platform to study biochemical threats and develop medical countermeasures against them.

Apparatus for measuring strength in biaxial compression.

Most measurements of compressive strength of ductile materials have involved Hopkinson-Kolsky bars or Taylor anvils placing samples in uniaxial compression. In these geometries, strain is limited by the tendency of the sample to petal, in analogy to necking in uniaxial tension. Estimation of strength for any other form of the stress tensor requires assuming a shape of the yield surface; because data exist only for uniaxial compression, these assumptions are untested. In an imploding spherical shell, compression is biaxial, the plastic strain may not be small, and the material behavior may be nonlinear as a result of work hardening and heating by plastic work. We outline a method of measuring the strengths of materials in biaxial compression, both quasistatically and dynamically, using the compression of thin spherical shells. We suggest surrounding the shell with an annulus filled with a mixture of H2 and Cl2 gases whose homogeneous ignition is initiated by a flash of blue and near-ultraviolet light. Less promising approaches are described in Appendixes A-C.

Corrosion of SiC-coated graphite susceptor by NH3 and Cl2

This study aims to investigate the corrosion of a SiC-coated graphite susceptor using NH3 and Cl2 in an epitaxial growth environment. The corrosion performance of NH3 with graphite and SiC-coated graphite was investigated through microstructure characterization and mass loss rate changes in detail. Gaseous NH3 had a high corrosion rate on the graphite substrate, but hardly reacted with the SiC coating. Additionally, analyses of the tested samples revealed that Cl2 gas corroded the SiC coating at high temperatures and formed many corrosion holes and residual free carbon on the surface. As the Cl2 concentration increased, the corrosion depth gradually increased. Further experiments on commercial SiC-coated graphite susceptors showed that Cl2 preferentially corroded the grain boundaries of the SiC coating, and then the grains were corroded, resulting in a decrease in the coating strength until cracking and failure.

Heterostructured Ga2O3-Activated Bi2O3 Sensors for Chlorine Monitoring

The nanocrystalline Bi2O3 powder was synthesized by ultrasonicated microwave irradiation by employing centrifugation technique at all normal conditions. Fabrication of thick films of pure Bi2O3 powder was made by screen printing and firing at 400oC for 30 min. Surface activations of the films involved the dipping of pure films into 0.01M aqueous solution of Gallium Nitrate for different intervals of time. The morphologies, surface topographies, constituents of elements present in the synthesized materials and crystallographic structures of the pure and surface activated films have been investigated by XRD, FE-SEM, E-DAX, etc. It has been investigated that, the Ga2O3 activated Bi2O3 (30 min) sample exhibits crucial response to 20 ppm Cl2 gas at 250oC. Electrical and gas monitoring performance of thick films of pure and activated Bi2O3 have been studied and discussed.

Theoretical investigation of Br2 and Cl2 detection by the pristine and Co-doped graphyne

The Br2 and Cl2 interaction with the intrinsic and Co-doped graphyne nanosheets has been explored by density functional theory calculations. Two vertical and parallel configurations were identified for Br2 and Cl2 adsorption. Calculations showed that the adsorption of Br2 was stronger than Cl2 on the graphyne nanosheet. Neither Br2 nor Cl2 could make serious changes to the HOMO–LUMO gap (Eg) and electrical resistance of pristine sheet. By manipulating the structure of pristine graphyne by Co atom, its reactivity and sensitivity dramatically improved toward Br2 and Cl2 gases. Compared to the Cl2, the Br2 much more decreases the electrical resistance and Eg of the Co-doped graphyne (~ −40.25%). Thus, the Co-doped graphyne may selectively recognize the Br2 gas in the presence of Cl2. The computed recovery time value for Br2 from the surface of the Co-doped graphyne is 36.4 s, which shows that the graphyne, as a sensor, benefits from a short recovery time to detect Br2.

Mn doped Ni-Zn ferrite thick film as a highly selective and sensitive gas sensor for Cl2 gas with quick response and recovery time

The Ni0.7-xMnxZn0.3Fe2O4 (x = 0.1–0.4) ferrites were characterized by X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy. The thick films of these ferrites were fabricated on a glass substrate to use as a Cl2 sensor. The ferrite thick film with composition x = 0.3 showed a selectively high response towards Cl2 gas at an operating temperature of 100 °C. The response varied from 115 to 212% for 20–300 ppm of Cl2 gas. The response time was found to be within 10 s while the recovery time was less than 15 s. The results were quite reproducible thus making this material a good sensor for Cl2 gas.

Photo-generated hydroxyl radicals contribute to the formation of halogen radicals leading to ozone depletion on and within polar stratospheric clouds surface

Polar stratospheric clouds (PSCs), of which the surface is a dynamic liquid water layer and might consist of aqueous HNO3 and H2O2, is a well-known key meteorological condition contributing to the ozone hole in the polar stratosphere. PSCs has been considered to provide abundant surface for the heterogeneous reactions causing the formation of the Cl2 and HOCl, which are further photolyzed into Cl and ClO radicals leading to the ozone destruction. Here we demonstrated that the sunlight drives the massive and stable production of OH radicals in aqueous HNO3 and its main photo-induced byproduct HNO2. We also found that the photo-generated OH radicals in aqueous HNO3, HNO2 and H2O2 have the remarkable capability to react with the dissolved HCl, Cl− and Br− to form halogen radicals. In addition, we observed that the H2O2 can react with dissolved HCl and Br− in darkness to form and release Cl2 and Br2 gases, which could further be photolyzed into reactive halogen radicals whenever sunlight is available. All these findings suggest that, except for the well-known heterogeneous reactions, photochemical reactions involving the aqueous HNO3 and H2O2 on and within PSCs surface might constitute another important halogen activation pathway for ozone destruction. This study may shed deeper insights into the mechanism of halogen radicals resulting in ozone depletion in polar stratosphere.

Polyoxotungstate intercalated self-assembled nanohybrids of Zn-Cr-LDH for room temperature Cl2 sensing

This article reports the preparation of mesoporous layered nanohybrids of zinc chromium layered double hydroxide (Zn-Cr-LDH) and polyoxotungstate (POW) anions via an exfoliation-reassembling process. The hybridization of Zn-Cr-LDH and POW anions leads to forming a layer-by-layer intercalated structure with a randomly interconnected mesoporous nanoplate network composed of ‘restacked POW intercalated Zn-Cr-LDH nanosheets’ (Zn-Cr-WO). The gas-sensing performance of the pristine Zn-Cr-LDH and Zn-Cr-WO was investigated for oxidizing (NO2 and Cl2), and reducing (LPG, H2, H2S, CO and NH3) gases at room temperature. The Zn-Cr-WO nanohybrids displayed the highest selectivity towards Cl2. The Cl2 gas response for the pristine Zn-Cr-LDH is 25.2% which further increased to 66.8% after hybridization with POW anions. The Zn-Cr-WO nanohybrids showed fastest response and recovery times of 5 and 133 s, respectively, at room temperature.

Full‐scale application of an electrochemical disinfection solution in a municipal drinking water treatment plant

AbstractFew studies employ electrochemical technology for urban water disinfection. This paper presents the replacement of a Cl2 gas system by an on‐site chlorine generation system (electrochemical disinfectant solution, EDS) and application at a water treatment plant. The study compares the Cl2 gas and EDS systems over 36 months, with 18 months for Cl2 gas and, after the implementation, 18 months for the EDS system (12‐month dry season and 6‐month wet season). Turbidity, residual Cl2, pH, total and faecal coliforms and DBPs were monitored. Turbidity was within legal limits and DBPs below both legal limits and limits of detection. For Cl2 gas, residual Cl2 suffered a decrease in wet and dry periods. However, the EDS maintained residual Cl2 to the network tips without significant variations, with operational costs reduced by ~41%. The study demonstrates that on‐site Cl2 generation can be employed for water disinfection for large urban areas with considerable economic and technical advantages.

Fundamental Study of Electrolysis of MgO in MgF2 - LiF - KCl Molten Salt Using Cu Cathode

For the commercial production of magnesium (Mg) metal using the electrolytic method, anhydrous magnesium chloride (MgCl2) is used as a feedstock. However, preparation of anhydrous MgCl2 is energy-intensive and toxic chlorine (Cl2) gas is generated during electrolysis. In order to resolve these problems, a novel molten salt electrolysis of magnesium oxide (MgO) using copper (Cu) cathode was investigated in this study. The effect of the electrolysis temperature, the size of the Cu metal pellets used for the cathode, the concentration of Mg in the Mg – Cu alloy, and the cathodic current density on the current efficiency were investigated. In addition, the reaction between the Mg – Cu alloy cathode and the alumina (Al2O3) crucible containing the Mg alloy during the electrolysis was analyzed. In the experiments, the electrolysis of MgO was conducted in a magnesium fluoride (MgF2) – lithium fluoride (LiF) – potassium chloride (KCl) molten salt using Cu cathode and carbon (C) anode by applying current in the range of 1.42 – 2.15 A at 1043 – 1173 K for 9.50 – 27.5 h in an argon gas atmosphere. After the electrolysis, the Mg – Cu alloys with a mixture of Cu2Mg and Cu (Mg) were obtained with 87.8 – 92.0 % current efficiency under certain conditions. Therefore, it was demonstrated that the green and effective electrolytic Mg production method using MgO, developed in this study, is feasible.

An Economic Electrochemical Hypochlorous Acid Maker for Covid-19 Control

It has been shown that HOCl can inactive numerous viruses, including Corona-19 Viruses in less than one minute. HOCl inactivates viruses, bacteria, endospore and fungi whilst being safe for human tissues with a 99.999% elimination rate. HOCl is listed on the United States Environmental Protection Agency’s List for Disinfectants for Use Against SARS-CoV-2 (Covid-19). It can be used conveniently as hand sanitizer, surface cleanser, food washing solution, fogging solution for school classrooms, buses, shops, restaurants, hotels, offices, theaters, airports, trains, gyms, etc. It is a green, safe, environmentally friendly and fully biodegradable liquid which acts as a very powerful antimicrobial and sterilizing solution.Most consumers purchase pre-made HOCl products produced in a large manufacture site. The pre-made HOCl hypochlorous acid products in the market are very expansive, mostly due to high cost for packaging, transportation, distribution, storage, and in-stability of the product, which normally has a lifetime of 6 -12 months. The capacity of current on-site HOCl generation products is either too big, or too small, only economical for large quantity consumers or single household uses. Due to the Corvid-19 pandemic, there is a strong need for a safe, on-site, on-demand medium-sized HOCl generation product, which uses only non-hazardous household chemicals and has a production capacity of about 10 gallons per day. Here we report our recent development of a compact and low cost HOCl on-site generator for daily disinfection applications against Corvid-19 virus. Compared to other products on the market, which normally use >2 g/L NaCl solutions, our device uses only 0.4 g/L NaCl solution. This is highly desired for environment fogging disinfection applications. Other advantages of our device include: 1) no noticeable Cl2 gas generation during HOCl production; 2) tap water can be used directly without softening treatment; 3) produce very stable products, with 90% HOCl Stability: > 100 hours.