Gaseous Contaminants Research Articles

Ability of a MoSi2 coating to resist erosion-corrosion from the impact of atomic oxygen

Atomic oxygen (AO), in the residual atmosphere of low-Earth-orbit space, may violently collide with spacecraft at a relative speed of up to 8 km/s and an impact energy of nearly 5 eV/atom. These collisions can lead to a series of physical and chemical reactions that may result in increased sputtering-erosion and corrosion of the exposed surface with performance degradation. This work examined the behavior of MoSi2, a commonly used coating, when exposed to AO using a ground-based space environment simulator. The erosion-corrosion kinetics and evolution of the microstructure and element distributions were analyzed. After MoSi2 was subjected to a total gas fluence of 9.72×1022 atoms/cm2 in 675 h, the erosion yield reached an exceptionally low value of 10-28 cm3/atom, indicative of its superior AO resistance, and XRD, SEM, XPS and EPMA were applied to analyze the phase transition of the coating surface: first it was released of adsorbed gas molecules and contaminants on the coating surface; then outside Mo and Si atoms were also sputtered, and the remaining Mo and Si atoms were gradually oxidized; finally, a continuous protective oxide film was generated which effectively resisting AO collisions. After AO impact, an ultrathin defensive granular oxide layer of MoO3 and SiO2 generated from the original smooth MoSi2 coating. Density functional theory calculations were conducted to clarify the thermodynamic and electronic structure mechanisms underlying the AO oxidation of the MoSi2 coating.

Promoting elemental mercury immobilization performance from smelting flue gas over a wide temperature range via cobalt-doped copper sulfide adsorbents

Copper sulfide (CuS) sorbent exhibits great potential for gaseous elemental mercury (Hg0) decontamination, but it still suffers from a narrow operating temperature. Therefore, designing advanced CuS sorbents that have a high activity level for capturing Hg0 and thermal stability at a high temperature range is challenging. Herein, we propose a metal doping strategy to fabricate a bimetallic sulfide adsorbent. Benefiting the unique structure and composition, a mesoporous structure and an abundance of unsaturated sulfur sites ensure that CuxCo(1–x)Sy provides a desirable level of adsorption for Hg0. The experimental results indicate the optimum Co doping mass concentration of 5 %. The Cu0.95Co0.05Sy not only performs satisfactory Hg0 adsorption at elevated temperatures (Hg0 average adsorption efficiency of over 97.3 %, Hg0 average adsorption rate of over 2.7 μg/g/min), but also presents an exciting regeneration and recycle performance (a Hg0 adsorption efficiency of over 94 % after 10 cycles). The adsorption capacity of Cu0.95Co0.05Sy at the breakthrough threshold of 25 % reaches 5.22 mg/g, surpassing most of metal sulfide sorbents for Hg0 immobilization at 150 °C. As far as Hg0 adsorption is concerned, the composition of typical smelting flue gases has almost no effect. According to further studies, unsaturated coordination short-chain sulfur (S22−) sites are essential for adsorption of Hg0 and are capable of directly forming α-HgS from Hg0. In both the contrast experiment and density functional theory calculations, the cobalt doping strategy enhances the thermal stability of the active S22− ligand and the Hg0 adsorption properties. This study not only provide a prospective adsorbent for Hg0 sequestration at wide temperature range, but also explores a method of utilizing gaseous contaminants for resource utilization.

A monolithic self-supporting ZnFe2O4/ZnO/ZnNi foam photocatalyst and application in the decomposition of gaseous benzene

Volatile organic compounds (VOCs) are major air pollutants which seriously affect ecological environment and pose threats to human health. In this investigation, a monolithic self-supporting ZnFe2O4/ZnO/ZNF(ZFO/ZnO/ZNF) photocatalyst was developed by in-situ growing ZnFe2O4 and ZnO on ZnNi foam (ZNF). Using benzene as a representative of the target gaseous contaminants, the optimal 5ZFO/ZnO/ZNF achieved a 99.8 % removal efficiency and 99.7 % mineralization efficiency within 20 min at an initial benzene concentration of 600 ppm under simulated sunlight irradiation. Moreover, this catalyst presents the lower ullage during gas–solid reaction, and thus enables durable recycling reuse of the photocatalyst, which still retains a 95.8 % benzene decomposition after 30th consecutive run. The mechanism studies reveal that the metal-mediated Z-type heterostructure of ZFO/ZnO/ZNF enhances rapid transportation of the photo-generated electrons and promotes redox potential, leading to the excellent photocatalytic oxidation activity and mineralization efficiency. This study highlights the potential of self-supporting monolithic metal-mediated catalysts and provides a key strategy for effective VOCs degradation.

Biochar improves growth and physiology of Swietenia macrophylla king in contaminated soil by copper

The production of açaí seed waste from the commercial and extractive exploitation of the Euterpe oleraceae palm tree is a serious problem that contributes to environmental contamination and production of greenhouse gases, a fact that suggests the need for an environmentally correct destination for this waste produced on a large scale. To this end, this study was conducted to evaluate the potential of acaí seed biochar (BCA) in mitigating the toxic effects of copper in Brazilian mahogany plants, analyzing biometrics and gas exchange. The experimental design was in randomized blocks, with five blocks, in a 4 × 3 factorial scheme, corresponding to the control (without Cu) and three concentration of Cu (200, 400, and 600 mg Cu kg−1) and three levels of BCA (0%, 5% and 10%) proportional to the amount of soil in the pots, totaling sixty experimental units. The use of 5% BCA in soils contaminated with up to 200 mg kg−1 Cu promoted biometric increase (height, diameter, number of leaves), maintaining gas exchange (photosynthesis, stomatal conductance, transpiration, internal carbon and internal/external carbon), and consequently, maintaining water use efficiency in plants under abiotic stress, resulting in plant growth. The findings of this study allow us to indicate the use of biochar in remediating and improving the growth of plants grown in copper-contaminated soils. The production of biochar from açaí seeds is an ecologically sustainable alternative, because it reduces its accumulation on public roads and contributes to reducing soil pollution. In the context of public policies, biochar production could be a source of income in the context of the bioeconomy and circular economy practiced in the Amazon, because it is produced in large quantities.

Measurement of Radon Gas Concentration in Sources of Drinking Water in Makurdi, Benue State, Nigeria Using Radon Detector (RAD-7)

Study’s Excerpt Radon gas contamination across diverse drinking water sources within Makurdi, Nigeria, was investigated. The RAD-7 detector was used, and the results revealed elevated radon levels exceeding WHO limits in some specific locations. There is a need for targeted risk mitigation strategies and continuous monitoring of Radon gas contamination in the area. Full Abstract Concern over radon gas's potential health risks when used or ingested in homes is growing, as is the issue with its presence in sources of drinking water. In this study, water samples were collected from various locations in Makurdi, Benue State, Nigeria, and the amount of radon gas present was measured using the Radon Detector (RAD-7). The study used a methodical sampling strategy to gather water samples from wells, boreholes, and surface water bodies throughout various Makurdi locations. The gathered water samples were examined using the RAD-7 detector, a trustworthy and sensitive device for measuring radon gas. The radon levels ranged from trace levels (20.0 ) to higher quantities (122.0 ), raising worries about potential health implications for nearby people reliant on these water sources. Thirty (30) samples of water were gathered for this investigation. The samples' radon content ranged from 10.3 to 122.0 Bq L-1, which is within the World Health Organization's (WHO) allowable limit and other regulatory bodies (100 Bq L-1) except in the sample collected from Court 5 and Logo1, which was higher than the set limit. The results of the analysis demonstrated that there were large variations within the range of 0.61 0.39-11.80 1.85 and a mean of 57.36 in the amounts of radon gas in the water samples obtained from the different sources. More research and monitoring are advised to gain a complete understanding of radon distribution and to develop workable radon risk reduction plans for water sources.

Quantitative Modelling of Residual Molecular Contamination in Low-Pressure Processing Environments

Some published experimental results of organic molecule contamination in vacuum processing are reviewed. The build-up of gaseous contamination from the residual gas in vacuum ambient to the surface of a substrate is quantitatively modelled. Calculations show that the build up of contaminants from the residual gas phase to the surface is very fast, essentially because in very dilute gas there are little molecular collisions to slow down the transport towards the substrate.

Distillation and gas stripping purification plants for the JUNO liquid scintillator

The optical and radiochemical purification of the scintillating liquid which will fill the detector of the JUNO experiment plays a crucial role in achieving its scientific goals. Given its gigantic mass and dimensions, and an unprecedented target value of about 3% at 1MeV in energy resolution, JUNO has set severe requirements on the parameters of its scintillator, such as attenuation length (Lat>20m at 430nm), light yield, and content of radioactive contaminants (238U,232Th<10-15g/g). To accomplish these needs, the scintillator will be processed using several purification methods, including distillation under vacuum and gas stripping, carried out in two large-scale plants installed at the JUNO site.In this paper, the layout, operating principles, and technical aspects which have driven the design and construction of the distillation and gas stripping plants are reviewed. The distillation is effective in enhancing the optical properties and removing high-boiling radioactive impurities (238U, 232Th, 40K), while the stripping process exploits pure water steam and high-purity nitrogen to extract gaseous contaminants (222Rn, 39Ar, 85Kr, O2) from the scintillator. The plant operating parameters have been tuned during the recent commissioning phase at the JUNO site and several quality control measurements and tests have been performed to evaluate the performances of the plants. Preliminary results on the efficiency of these purification processes will be shown.

Bacterial contamination and greenhouse gas emissions: A randomised study of reuse versus single-use of infusion-set components for intravenous anaesthesia.

Reusing anaesthesia infusion-set components may reduce the climate impact from plastic waste and discarded medications. Infusion-set contents can be shielded from patient contact by single use of an infusion line fitted with dual antireflux valves, preventing retrograde entry of microorganisms, and eliminating the risk for patient-to-patient cross-contamination. However, infusion-set contamination from compromised aseptic handling could affect quality of care. To determine the prevalence of infusion-set bacterial contamination and compare the climate effects, we randomised operating rooms scheduled for total intravenous anaesthesia to handle procedures by infusion-set reuse or single-use. Both methods used dual single-use antireflux valves. The primary outcome was infusion-set bacterial contamination assessed by aerobic culture of infusion-set fluid collected after each procedure. The secondary outcome was CO 2 emissions (CO 2 -eq) estimated by life cycle assessment of component and medication use. To assess feasibility of detecting an inter-method difference in bacterial contamination, an interim analysis was planned after including at least 150 procedures per group. After allocating 54 operating rooms per method, 189 and 159 procedures of reuse and single use were included. Reuse permitted a median of three procedures per infusion set (range 1 to 8). Positive cultures occurred in two procedures per method [mean (95% CI)]; prevalence 1.15% (0.03 to 2.27); relative risk of reuse versus single use 0.84 (0.12 to 5.93), P = 0.861. As prespecified, inclusion was stopped due to futility. The median (95% CI) per-procedure climate emissions were 0.43 (0.41 to 0.47) and 1.39 (1.37 to 1.40) kg CO 2 -eq for reuse and single-use respectively; difference -0.96 (-0.99 to -0.93), P < 0.0005. The main sources for climate emissions were production of infusion-set components and waste handling. We conclude that the prevalence of bacterial contamination was low for both methods. A much larger study would be needed to detect an inter-method difference. Reuse of infusion-set components allowed significantly reduced intravenous anaesthesia climate emissions.

Impact of Cu content on the activity of TiO2-based catalysts for toluene oxidation

Toluene is one of the most toxic contaminants in industrial waste gases, it can enter the body through the respiratory system and skin. Long-term exposure to it can lead to skin inflammation and neurasthenia, and even cause lesions in organs. Over the years, catalytic oxidation technology has been extensively employed to the remove of toluene, and oxides, especially copper oxide, is considered to be an effective catalyst technology and has been extensively studied. In this work, we introduced CuO as an active species to investigate the impact of Cu content in TiO2@CuO (TC-x, x=1, 2, 3, and 5) catalyst on the activity, reusability, and stability of toluene oxidation. The result demonstrated that the addition of Cu species, facilitating the generation of active oxygen obviously reduced the complete oxidation temperature of toluene. Among them, TC-3 catalyst exhibited the highest activity (T50 = 234 ℃, T90 = 289 ℃, and T100 = 310 ℃, with Ctoluene=1000 ppm, WHSV=20,000 mL/ (g h)), great reusability, and stability for toluene degradation. According to the in-situ DRIFTS, the ultimate degradation products of toluene were CO2 and H2O, which were clean and free of secondary pollution.

Study on the phase transformation mechanism and influencing factors of inorganic condensable particulate matter from coal-fired power plants

In this study, the concentration of inorganic ions (SO42−, NH4+, NO3− and NO2−) and morphological characteristics of condensable particulate matter (CPM) were investigated to elucidate the formation mechanism of inorganic CPM from ultra-low emission coal-fired power plants. The concentration of inorganic ions increased with the increase of H2O content and concentration of inorganic gaseous contaminants (SO2, NOX and NH3), and decrease of condensation temperature, indicating the enhancement of heterogenous reaction in the saturated flue gas. Furthermore, NOX and SO2 could undergo redox reactions, leading to an elevation in the concentration of SO42− and NO3−. Additionally, the introduction of NH3 resulted in increased concentrations of SO42−, NO3−, and NO2−, highlighting the significant role of NH3 neutralization in CPM nucleation. The condensation of SO3/sulfuric acid aerosols was enhanced under saturation conditions, and SO2 and SO3/sulfuric acid aerosols could contribute synergistically to the formation of SO42−. Moreover, morphological analysis revealed the presence of both well-aggregated solid CPM and dispersed liquid CPM, confirming the formation of inorganic CPM during fast condensation. Furthermore, the detected CPM were composed of S and O, which identified the significant role of sulfates in the inorganic CPM. These findings provide valuable insights for the control of inorganic CPM in flue gas systems.

Hygienic assessment of occupational conditions and schedule of railway employees

Introduction. Railway transport is one of the leading branches of the national economy, though more than 50% of the railway employees have to undergo some occupational hazards [1]. In recent years, with the introduction of new technologies, significant changes have occurred in the rolling stock. Up to date research on the hygienic assessment of occupational conditions and schedule of railway employees is needed. The purpose of the study is to investigate the occupational conditions and schedule of railway employees, and to identify the principal occupational hazards. Materials and methods. The materials of the special assessment of the occupational conditions at workplaces in the divisions of the South-Eastern Directorate of Traction, as well as the results of the proper hygienic studies, including railway employees inquiry on occupational hazards (n=300). The analysis of the occupational conditions was carried out according to Guide No. 2.2.2006–05. Results. According to the results of an objective assessment of occupational conditions of railway employees, the main occupational hazard is high work intensity. The second most important factor is noise. Profound hygienic studies show that such occupational hazards as vibration, electromagnetic field (EMF), dust, etc. should be paid more attention. Limitations. The limitations of the study are related to their volume. The data of the special assessment of the occupational conditions and production control were used for the period of 2019–2023, the sample size of the respondents was 300 employees (2022). Conclusion. According to the results of an objective assessment of occupational conditions of railway employees, the main occupational health risk factor is high work intensity accompanied by a shift work schedule. The second most important factor is noise. The results of the questionnaire are generally consistent with the results of the special assessment of occupational conditions of railway employees, but also indicate other occupational hazards the employees to undergo including vibration, gas and dust contamination, exposure to electromagnetic fields, the level of which generally meets the requirements of hygienic standards. The ranking of the railway employees was carried out, occupations at risk of developing general pathological syndromes were identified.

Gaseous contaminant transfer in membrane-based air-to-air energy exchangers

Membrane-based air-to-air energy exchangers (M−AAEEs) transfer heat and moisture between building exhaust air and fresh ventilation air streams through a membrane, thereby reducing the energy required for conditioning the fresh ventilation air. Energy exchangers are typically used in buildings with relatively clean building exhaust air, such as office buildings and schools. Recently interest in using energy exchangers in a wider range of buildings has grown, to reduce the energy consumption associated with the heating, ventilating, and air-conditioning (HVAC) systems in these buildings. However, if the building exhaust air is not clean, as would be the case for laboratories or factories, new risks are encountered when using energy exchangers. It is possible that gaseous contaminants in the exhaust air may also transfer along with the moisture through the membranes, contaminating the incoming fresh ventilation air. Current test standards provide a test procedure to determine the contamination of the fresh ventilation air by measuring the transfer of an inert tracer gas in an energy exchanger. However, the tracer gas test may not represent the transfer of common indoor air contaminants due to differences in their transport properties. Therefore, in this study, an experimental facility is developed to determine the transfer of seven different contaminants through two membranes (porous and dense) at different flow rates. Contaminant transfer is quantified using a parameter called the exhaust contaminant transfer ratio (ECTR), which gives the fraction of the contaminants transferred from the exhaust air to the fresh ventilation air. A theoretical model based on the effectiveness-number of transfer units (ε-NTU) correlation and moisture transfer resistance of the membrane is presented to determine transfer through porous membranes and validated with experimental results. The major contribution of this paper is that it presents a simple method to predict the transfer of different contaminants through a porous membrane based on the moisture transfer resistance of the membrane at different operating conditions. It is found that as contaminant diffusivity decreases, ECTR generally also decreases, and as the flow rate increases, ECTR decreases, which is consistent with the predictions from the correlation.

Використання комплексу газогрунтової зйомки та геофізичних досліджень у задачі окреслення території грязьового вулканізму в межах Розвадівської площі Львівської області

The purpose of the research was to substantiate the scientific basis behind the formation of a mud volcano within a specific section of the Precarpathian depression. It also aims to examine the existence of a near-fault shallow gas deposit in the Rozvadiv area and its possible impact on gas-soil surveying and electrometry fields. The relevance of the work is determined by the need to solve the ecological problem of environmental pollution with hydrocarbon gases, as well as to establish and forecast the degree of emissions of the gas-mud mixture. At the same time, the problem of the presence (or absence) of the relationship between the influence of the Rudnyk gas-prospecting area, which is impacted by drilling, and the Rozvadiv deposit mentioned above is solved by comparing the results of gas-soil and geophysical surveys on a significant territory covering the specified areas. The research methodology consists of the following: 1) application of research with different physical justifications (gas-soil survey and electrometry); 2) comparison of the survey results from the same area and the same grid of observations; 3) detection of anomalies within the studied territory and their interpretation from the point of view of the development of mud volcanism. Research results. The information basis of gasometry involves direct measurements of free gas in a observation regular system in the soil environment atmosphere, their statistical characteristics, and calculated indicators of gas contamination. Therefore, the gas distribution maps are informative. The applied research using the method of Earth’s natural pulsed electromagnetic field made it possible to differentiate the area according to the intensity degree of electromagnetic radiation, taking into account the different depths of the sources, and, thus, identify areas of stressed-strain state of rocks and qualify them by the causes. The scientific novelty lies in the following: 1) indicating the absence of connections between the massif impacted by drilling and a natural disaster; 2) specifying the causes of the natural disaster and its substantiated mechanism and classifying the event as a mud volcano. Practical significance. Interpretation of the obtained results makes it possible to determine the causes of the extraordinary geological event in the Rozvadiv area of the Lviv region, classify the event and its consequences as a manifestation of elements of mud volcanism, and establish the absence of a relationship between the specified event and man-made impact (drilling) of the geological environment in the neighbouring areas.

Environmental Monitoring System using Wireless Multi-Node Sensors based Communication System on Volcano Observations Drones

Indonesia is on the Ring of Fire and has the world's most active volcanoes. Volcanic activity has a significant effect on the landscape and on the people who live there. The difficulty of evacuating and helping victims requires hard work and sometimes even the safety of the rescue team itself. For this reason, high-tech tools are needed. Unmanned aerial vehicles (UAVs), also called drones, have become a hopeful tool for remote environmental monitoring in recent years. The system design has a monitoring platform, gateway, and sensor nodes attached to the UAV, which monitors the content of toxic gas contamination in the air. Using IoT technology, sensor data is sent wirelessly to a central monitoring station for a thorough and accurate volcanic activity study. This system is a flexible and complete way to monitor volcanic activity, learn more about it, and make it easier to respond to disasters. Tests are also done to measure system speed, including latency, and determine network service quality. The results show that data is successfully sent in real-time from the sensor nodes to the monitoring system. The average Round-Trip time for the payload transmission is 446.046226 ms. This shows how well the system works to send data from the sensors connected to the UAV to the monitoring station. The UAV has sensor nodes and a monitoring system platform. These can be used to build and optimize disaster mitigation systems.

Effects of chemically-reductive trace gas contaminants on non-thermal plasma inactivation of an airborne virus

Transmission of airborne infectious diseases poses great risk for public health and socio-economic stability, thus, there is a need for an effective control method targeting the spread and transmission of pathogenic aerosols. The existence of chemically-reductive trace air contaminants in animal agriculture may affect the oxidation inactivation process of pathogens. In this study, we report how the presence of such gasses impacts the effectiveness of using non-thermal plasma (NTP) within a packed-bed dielectric barrier discharge reactor to inactivate MS2 bacteriophage. Inactivation of the aerosolized bacteriophage is determined by the combination of viability and polymerase chain reaction assays. Using a plasma power source with a voltage of 20 kV and frequency of 350 Hz, after differentiating and excluding the physical removal effects of viral aerosols potentially caused by plasma, the baseline inactivation of MS2 aerosol in air has been determined based on an overall air flow rate of 200 Liters per minute and plasma discharge power of 1.8 W. When either ammonia or hydrogen sulfide gas is introduced into the airstream at a concentration of 1 part per million, the NTP virus inactivation efficiency is reduced to around 0.5-log from the 1-log baseline inactivation in air alone. Higher concentrations of those gasses will not further inhibit the effectiveness of plasma inactivation.

Examining the relationship between atmospheric pollutants and meteorological factors in Asansol city, West Bengal, India, using statistical modelling.

Meteorological conditions significantly impact ambient air quality in urban environments. This study focuses on Asansol, known as the "Coal City" and the "Industrial Heart of West Bengal," a notable hotspot for air pollution. Despite its significance, limited research has addressed the influence of meteorological factors on key air pollutants in this urban area. From January 2019 to December 2023, this investigation explores the relationships between meteorological parameters (including atmospheric temperature, relative humidity, rainfall, wind speed) and the concentrations of crucial air pollutants (PM2.5, PM10, NO2, SO2). Temporal trends in air pollutant concentrations are also analysed. The Spearman correlation method is used to establish associations between pollutant concentrations and meteorological variables, while multiple linear regression (MLR) models are employed to assess meteorological factors and potential impact on pollutant concentrations. The analysis reveals a decreasing trend in pollutant concentrations in Asansol. Temperature exhibits negative correlations with all pollutants in all seasons except for a positive correlation during the monsoon. Rainfall consistently displays significant negative correlations with pollutants in all seasons. Relative humidity is negatively correlated with pollutants in all seasons, and wind speed, except during the post-monsoon season, shows negative correlations with all pollutants. Linear models excel in predicting particulate matter concentrations but perform poorly in predicting gaseous contaminants. Accounting for seasonal fluctuations and meteorological parameters, this research enhances the accuracy of air pollution forecasting, contributing to a better understanding of air quality dynamics in Asansol and similar urban areas.

Investigation of the adsorption behaviour of toxic heavy metals and bacteria on two allotropes of low dimensional boron nitride: Implications for detection and elimination

In this research, the focus was on two 2D allotropes of boron nitride (BN), specifically Haeck-BN and Twin-BN. They exhibit unique structural and electronic characteristics, making them suitable for sensing applications. High surface area materials offer numerous affinity sites for heavy metal ions and toxic molecules. Using density functional theory (DFT), the adsorption mechanisms of various contaminants in gas (solvent) phase on both pristine and doped Haeck-BN and Twin-BN were investigated. Pronounced adsorption of arsenic (As) and lead (Pb) was observed on pristine Twin-BN sheets, with adsorption energies of −2.83 eV (−2.86 eV) and −2.03 eV (−2.39 eV), respectively. Haeck-BN showed weaker interactions, with adsorption energies of −1.48 eV (−1.55 eV) for As and −0.64 eV (−0.92 eV) for Pb. Significant adsorption of specific amino acids, integral components of bacterial cell walls, was noted on both pristine and silver-modified sheets. The electronic properties showed significant shifts upon molecular adsorption, confirming their sensitivity towards foreign contaminants. The high adsorption energies of amino acids suggest potential applications in efficient bacterial inactivation for water purification. While real-world scenarios pose challenges, the calculations provide valuable insights for potential use of these nanosheets in advanced water purification membrane technology.

Red mud: Characteristics, utilization, and environmental remediation strategies in the aluminium industry

Aluminium plants generate a substance identified as red mud, which is an alkaline atrophy product. As the aluminium industry expands, the accumulation of red mud has become a more pressing concern. Various atrophy treatment technologies have been developed to utilize red mud as a material for environmental remediation. These substances, also identified as Red Mud Ecological Rehabilitation Ingredients (RM-ERMs), are created by stimulating red mud, fusing it in a complementary manner with additional compounds, or removing useful components from it. RM-ERMs find application in three main areas: purifying wastewater, treating atrophy gases, and remediating soil. The extremely alkaline nature of red mud is harnessed in the making of RM-ERMs, offering a window to perk up the environment through purification methods. The utility of RM-ERMs has shown promise as a potential method for simultaneously addressing various types of waste. This review provides an introduction to the physical and chemical characteristics of red mud, and summarizes the active mechanism of RM-ERMs in addressing specific contaminants in wastewater, atrophy gases, and soil. Additionally, a review of current challenges in the field of RM-ERMs offers crucial insights and recommendations for future research in this area.

A new gas detection technique through cross-correlation with a complex aperiodic FBG

Optical cross-correlation is a technique that can achieve both high specificity and high sensitivity when deployed as the basis for a sensing technology. Offering significant gains in cost, size and complexity, it can also deliver significantly higher signal-to-noise ratios than traditional approaches such as absorption methodologies. In this paper, we present an optical cross-correlation technology constructed around a bespoke customised Fiber Bragg Grating (FBG). Exploiting the remarkable flexibility in design enabled by multiple aperiodic Bragg gratings, optical filters are devised that exactly mimic the absorption features of a target gas species (for this paper, acetylene C2H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_2H_2$$\\end{document}) over some waveband of interest. This grating forms the heart of the sensor architecture described here that employs modulated optical cross-correlation for gas detection. An experimental demonstration of this approach is presented, and shown to be capable of differentiating between different concentrations of the C2H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C_2H_2$$\\end{document} target gas. Furthermore these measurements are shown to be robust against interloper species, with minimal impact on the detection signal-to-noise arising from the introduction of contaminant gases. This represents is a significant step toward the use of customised FBGs as low-cost, compact, and highly customisable photonic devices for deployment in gas detection.

Enhanced SO2, NO, and Cr (VI) removal by lignin-derived high N-doped activated carbon through one-pot strategy: Structure development, structure–performance relationship and mechanism insight

The production of high-performance activated carbon (AC) is recognized as an essential strategy for the effective utilization of lignin resources. In this work, the N-doped AC was successfully prepared by blending sodium lignosulfonate (SL) and different ratios of FeCl3 through one-pot strategy. The AC structure evolution and performance were obtained by a series of characterization and tests. The results showed that, during the activation process, FeCl3 first complexed with urea and catalyzed the depolymerization of SL, and the rapid pore development was mainly caused by the template, including formed FeCl2, Na2Fe3Cl8 and Na6FeCl8. The ratio of FeCl3/SL adjusts the AC physicochemical texture. AC-3 processed a super total specific surface area and pore volume, respectively up to 2048 m2/g and 1.47 cm3/g. Meanwhile, AC-2 showed a higher nitrogen content of 11.4 %. The as-prepared AC shows super desulfurization, denitrification and Cr (Ⅵ) removal ability. AC-2 displayed maximum sulfur capacity and NO conversion, up to 199.1 mg/g and 42.4 %. This enhanced performance is primarily attributed to the pore structure induced by FeCl3 activation, which provides a foundation for adsorption and catalytic processes, further augmented by the increased active sites due to nitrogen doping. AC-3 achieved an extremely high Cr (VI) adsorption capacity, up to 386.2 mg/g, which was primarily attributed to the redox effect of N-containing and O-containing groups on Cr (VI), in addition, the effect of physical adsorption including pore structure is not neglectable. This study highlights the significant potential of environmentally friendly lignin-based porous carbon materials for removing contaminants in both gas and liquid phases.