Nitrogen Oxides Research Articles

Investigation of phenol adsorption performance and mechanism using Na2EDTA-modified activated biochars produced from a fluidized bed pyrolysis system

The study investigated the characteristics and mechanisms of phenol adsorption in three types of modified activated biochars (rice straw, rice husk, and sawdust) obtained through fluidized bed pyrolysis system, particularly focusing on biochars activated with KOH and modified with Na2EDTA. The experimental comprehensively analyzed the morphology of biochars through nitrogen adsorption-desorption (BET), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), while employed mathematical descriptions with isotherm, adsorption kinetics, and thermodynamics models. The adsorption process could be better described by the pseudo-second-order kinetic model and Langmuir isotherm model, indicating the spontaneous and exothermic reaction. After being activated by KOH, results showed that KOH could generate potassium vapor for etching carbon layers at high temperatures, forming a microporous structure. With the KOH activation and Na2EDTA modification, the amino (-NH2) and carboxyl (-COOH) groups were effectively loaded on the adsorbents. Especially, after Na2EDTA modification, an N1s peak appeared in the XPS spectrum, the peak area ratios of pyrrolic-N and graphitic-N drop from 54.20 % to 21.45%–49.15% and 16.62%, while that of pyridinic-N and nitrogen oxides correspondingly increased, indicating the presence and alteration of nitrogen-containing functional groups, promoting the formation of π-π bonds, and strengthening of π-π dispersion effects. Meanwhile, the specific surface area reaches 1143.60 m2/g to 1337.20 m2/g, the maximum adsorption capacities reach 156.29 mg/g to 195.17 mg/g, which outperform the commercial activated biochars. This finding suggests that Na2EDTA -modified biochars by fluidized bed could enhance the adsorption capacity for phenol, and offer economic feasibility and high production technical for the environmental protection and wastewater treatment.

Catalytic NO<sub>x</sub> Aftertreatment—Towards Ultra-Low NO<sub>x</sub> Mobility

Article Catalytic NOx Aftertreatment—Towards Ultra-Low NOx Mobility Navjot Sandhu * , Xiao Yu, and Ming Zheng Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, ON N9B 3P4, Canada * Correspondence: sandh12p@uwindsor.ca Received: 26 January 2024 Accepted: 13 March 2024 Published: 20 March 2024 Abstract: The push for environmental protection and sustainability has led to strict emission regulations for automotive manufacturers as evident in EURO VII and EPA2027 requirements. The challenge lies in maintaining fuel efficiency and simultaneously reducing the carbon footprint while meeting future emission regulations. Nitrogen oxides represent one of the major and most regulated components of automotive emissions. The need to meet the stringent requirements regarding NOx emissions in both SI and CI engines has led to the development of a range of in-cylinder strategies and after-treatment techniques. In-cylinder NOx control strategies including charge dilution (fresh air and EGR), low-temperature combustion, and use of alternative fuels (as drop-in replacements or dual fuel operation) have proven to be highly effective in thermal NOx abatement. Aftertreatment methods are required to further reduce NOx emissions. Current catalytic aftertreatment systems for NOx mitigation in SI and CI engines include the three-way catalyst (TWC), selective catalytic reduction (SCR) and lean NOx trap (LNT). This review summarizes various approaches to NOx abatement in IC engines using aftertreatment catalysts. The mechanism, composition, operation parameters and recent advances in each after-treatment system are discussed in detail. The challenges to the current after-treatment scenario, such as cold start light off, catalyst poisoning and the limits of current aftertreatment solutions in relevance to the EURO VII and 2026 EPA requirements are highlighted. Lastly, recommendations are made for future aftertreatment systems to achieve ultra-low NOx emissions.

CASE STUDY ON SMOG FREE CITY

In one of the world’s most polluted cities smog pollution in form of gases like CO(carbon mono-oxide) , NO (nitrogen oxide) and hydrocarbon are very harmful for human beings. It is one of the most serious public health concerns in the worldwide. We are in need of oxygen supply that too in pure form. Smog is a kind of visible. Photochemical smog i.e. man -made smog derived from forest and agricultural fires. This may cause health problems like difficulty in breathing and can be dangerous for cancer. So, for reducing the smog from the air there are various structures like Smog free tower. These towers are more effective in most of polluted cities. This study aimed to aware and give some preventive practices of smog pollution and also shows the design of smog free tower. Key Words: smog, pollutions, nitrogen oxide, carbon mono-oxide, nitrogen di-oxide

Road traffic flow and air pollution concentrations: evidence from Japan

AbstractVehicular emissions are a major global health concern. The aim of this study is to examine the short-term relationship between road traffic flows and air pollution concentrations in Japan. Our approach involves matching hourly data from the 2015 Road Traffic Census to data from nearby air pollution monitoring and meteorological stations and estimating a dynamic panel model. We focus on four pollutants designated under the vehicle emission standards of Japan: nitrogen oxides (NOx), carbon monoxide (CO), nonmethane hydrocarbons (NMHC), and fine particulate matter (PM2.5). The standard estimates indicate that short-run pollution concentration-road traffic flow elasticities are 0.04–0.05 for NOx, CO, and NMHC, and insignificant for PM2.5. Long-term effects are also estimated. We apply the estimates to a case study on the link between road traffic flows and meeting the new World Health Organization air quality guidelines.

Experimental investigation of hydrogen enriched natural gas combustion with a focus on nitrogen oxide formation on a semi-industrial scale

Combustion of hydrogen-enriched natural gas is a valuable short-term strategy for reducing CO2 emissions from high temperature industrial heating. This paper presents several experiments on combustion characteristics and the formation of nitrogen oxides. The experiments included hydrogen contents up to 100% and fuel heat inputs up to 75 kW. Water-cooled lances were used to influence the furnace temperature. The analysis includes the distribution of furnace temperatures, the composition of flue gas, the cooling capacity of the lances under steady-state operating conditions, and OH*-chemiluminescence imaging of the near burner region. The presented results demonstrate the dependence of furnace conditions and NOX formation on various factors, such as different air inlet fluxes, furnace temperature, and fuel composition, for constant heat inputs. Efficiency increased by up to 5.5% and significant changes in flame shaped along with a maximum increase in NOX emissions when comparing natural gas to hydrogen was measured at 167%.

Unravelling the reaction mechanism for the AP decomposition over MgO: A density functional theory study and microkinetic simulation

The detailed reaction mechanisms for the decomposition of ammonium perchlorate (AP), an essential component of solid composite propellants, are poorly understood due to the ultrafast and complex reactions. Density functional theory and kinetic simulation are utilized to calculate the decomposition reaction of AP on the surface of magnesium oxide and present a detailed decomposition network. Using a proton transfer mechanism, NH3 and HClO4 are the major production at low-temperature decomposition of AP, involving two elementary steps. AP is completely decomposed in the high-temperature reaction stage. In this work, it is found that the decomposition of NH3 is mainly in the form of oxidative dehydrogenation, while HClO4 proceeds along the pathway HClO4→ClO3→ClO2→ClO→Cl, and the final nitrogen oxides, chlorine oxides are formed. These simulations provide offer atomic-level understanding of the complex reaction kinetics of AP, which can be applied to explore the reaction mechanisms of other metal oxides.

A quantitative analysis of causes for increasing ozone pollution in Shanghai during the 2022 lockdown and implications for control policy

Ground-level ozone (O3) pollution is a major air quality issue in densely populated urban areas. Despite a significant decline in human activities in the megacity Shanghai from March 28 to May 31, 2022, ground-level measurements indicate a rise in maximum daily average 8-h (MDA8) O3 concentrations in comparison to the corresponding period in 2021. There is a need for quantitative analysis to identify the reasons behind this increasing O3 concentration. We analyzed ground measurements of O3 and its precursors and meteorological parameters made in Shanghai, using random-forest (RF) model and chemical box model to elucidate the roles of meteorological and chemical factors in influencing O3 concentrations. Across urban, suburban, semi-rural, and coastal sites, the urban center of Shanghai experienced the largest decreases in the concentrations of nitrogen oxides (NOx; 53%) and volatile organic compounds (VOCs; 52%), with the most notable rise in MDA8 O3 concentrations (16%). RF modeling indicates that meteorological factors reduced MDA8 O3 concentrations by a marginal 3%, whereas a decline in anthropogenic emissions resulted in a 17% increase in MDA8 O3 concentrations. Chemical box modeling at the Pudong urban site indicates that while the decline in VOCs reduced O3 production by 42%, this was negated by a reduction in NOx from traffic emissions, which enhanced O3 production by 51%, resulting in an increase in O3 production overall. Despite a halving in precursor levels, Shanghai's urban centre remains predominately under VOC-limited conditions throughout the study period, with high NO2 levels from the petrochemical industry and traffic emissions. Joint control of anthropogenic VOCs (AVOCs) and NOx, with a ratio greater than 1.29, could help avoid exacerbation of O3 pollution and reduce NO2 pollution. Our findings emphasize the necessity of reducing industrial emissions along with ongoing green transportation strategies for alleviating O3 pollution in megacities like Shanghai.

Association Between Long‑Term Exposure to Air Pollution and the Rate of Mortality After Hip Fracture Surgery in Patients Older Than 60 Years: Nationwide Cohort Study in Taiwan.

To enhance postoperative patient survival, particularly in older adults, understanding the predictors of mortality following hip fracture becomes paramount. Air pollution, a prominent global environmental issue, has been linked to heightened morbidity and mortality across a spectrum of diseases. Nevertheless, the precise impact of air pollution on hip fracture outcomes remains elusive. This retrospective study aims to comprehensively investigate the profound influence of a decade-long exposure to 12 diverse air pollutants on the risk of post-hip fracture mortality among older Taiwanese patients (older than 60 years). We hypothesized that enduring long-term exposure to air pollution would significantly elevate the 1-year mortality rate following hip fracture surgery. From Taiwan's National Health Insurance Research Database, we obtained the data of patients who underwent hip fracture surgery between July 1, 2003, and December 31, 2013. Using patients' insurance registration data, we estimated their cumulative exposure levels to sulfur dioxide (SO2), carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), particulate matter having a size of <10 μm (PM10), particulate matter having a size of <2.5 μm (PM2.5), nitrogen oxides (NOX), nitrogen monoxide (NO), nitrogen dioxide (NO2), total hydrocarbons (THC), nonmethane hydrocarbons (NMHC), and methane (CH4). We quantified the dose-response relationship between these air pollutants and the risk of mortality by calculating hazard ratios associated with a 1 SD increase in exposure levels over a decade. Long-term exposure to SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 demonstrated significant associations with heightened all-cause mortality risk within 1 year post hip fracture surgery among older adults. For older adults, each 1 SD increment in the average exposure levels of SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 corresponded to a substantial escalation in mortality risk, with increments of 14%, 49%, 18%, 12%, 41%, 33%, 38%, 20%, 9%, and 26%, respectively. We further noted a 35% reduction in the hazard ratio for O3 exposure suggesting a potential protective effect, along with a trend of potentially protective effects of CO2. This comprehensive nationwide retrospective study, grounded in a population-based approach, demonstrated that long-term exposure to specific air pollutants significantly increased the risk of all-cause mortality within 1 year after hip fracture surgery in older Taiwanese adults. A reduction in the levels of SO2, CO, PM10, PM2.5, NOX, NO, NO2, THC, NMHC, and CH4 may reduce the risk of mortality after hip fracture surgery. This study provides robust evidence and highlights the substantial impact of air pollution on the outcomes of hip fractures.

Reducing the emission of harmful gases from pig manure using different doses of biodestructors

The anthropogenic impact of the functioning of livestock complexes on the environment is caused by the release of gaseous air pollutants into the atmosphere, including harmful gases such as methane (CH4), carbon dioxide (CO2), ammonia (NH3), hydrogen sulfide (H2S), nitrogen oxide (NO) and nitrous oxide (N2O). The latter cause environmental degradation and have a negative impact on the climate balance of the planet. Therefore, the basis of the planned research was to evaluate the effectiveness of different doses of "Scarabei" and "Vodohrai Chystyi Khliv" biodestructors on the emission of harmful gases from pig manure in vitro. In the process of conducting experimental studies, it was established that the addition of "Scarabei" and "Vodohrai Chystyi Khliv" biodestructors to pig waste helps to reduce the level of CH4 emissions up to 14.4% and 22.3%, NH3 up to 23.7% and 39.7%, H2S up to 22.2% and 38.2%, CO2 up to 23.4% and 35.6%, NO up to 14.6% and 23.2%, respectively. Simultaneously, with the reduction of emissions of the studied gases, biodestructors also provide a lower level of pH, i.e., its shift to the acidic side up to 5.54 ("Scarabei") and 5.12 ("Vodohrai Chystyi Khliv"), against 6.2–6.5 – in the control. Thus, the results obtained indicate the feasibility of using the studied biodestructors, such as "Scarabei" and "Vodohrai Chystyi Khliv" at a dose of 40 g/m3 for lower emissions of harmful gases, both when storing manure in storage facilities (lagoons) and directly in the pig keeping premises, which will prevent the negative impact of intensive pig production on the environment.

Synergistic polarity interaction and structural reconstruction in Bi2MoO6/C3N4 heterojunction for enhancing piezo-photocatalytic nitrogen oxidation to nitric acid

Constructing heterojunctions has emerged as a widely embraced strategy for augmenting piezo-photocatalytic activities. However, the synergistic pressure response, the construction of charge transfer, polar direction sites and active site are often left in the basket. Here, the carboxylated C3N4 and Bi2MoO6 S-scheme heterostructure was elaborately designed for piezo-photocatalytic nitrogen oxidation towards nitric acid. Extensive research evidence proves that Bi-COOH interaction between Bi2MoO6 and g-C3N4 leads to the occurrence of polarity interaction and structural reconstruction. Those initiatives facilitate the efficient distribution of charges and acts as a pathway for carrier migration, thereby promoting charge transfer and the large intrinsic dipole moment. Furthermore, the combination of polarity interaction and structural reconstruction strengthens N2 polarization and electron transfer, facilitating the breaking of NN bonds and reducing activation energy. Consequently, the optimal BCO-3 catalyst revealed outstanding nitric acid production rates of 5930 μg g−1 h−1 under the stimulation of ultrasonic and light illumination, which is 3.66 times higher than that of C3N4-Bi2MoO6 heterostructure and superiors to various piezo-photocatalysts. Our research endeavors present promising prospects for the design of advanced catalysts and contribute to a profound comprehension of molecular activation processes in heterojunction.

The response mechanism and dynamic succession of microbial community in activated sludge system under dexamethasone stress

The mass production and widespread use of dexamethasone (DEX) during the COVID-19 pandemic inevitably led to the increase of residue concentrations in wastewater treatment plants. In this study, the effects of DEX at different concentrations on the activated sludge system were investigated. The results indicated that organic matter removal and ammonia nitrogen oxidation were inhibited. The effluent COD and TN gradually increased with increasing DEX concentration. The extracellular polymeric substance was secreted as a protective barrier against DEX stress, ensuring the integrity of the cell membrane. According to assembly mechanism analysis, the relative importance of homogeneous selection in deterministic processes gradually increased under DEX stress, which acts as the main driving force to alter the distribution of abundance and rare taxa, causing the decrease of rare taxa and community diversity, thus forming more homogeneous and similar community structure. These negative consequences, coupled with the inhibition in autotrophic nitrifiers such as Nitrosomonas and Ellin6067, and the decrease in gene abundance of nitrification metabolism including AmoCAB and Hao, were directly responsible for the obvious deterioration of NH4+-N oxidation capacity. This study provided reliable experimental data about the effects of DEX on activated sludge systems, which is conducive to reducing the environmental risk of DEX and maintaining the stable operation of the activated sludge system.

An Interpretable Time Series Forecasting Model for Predicting NOx Emission Concentration in Ferroalloy Electric Arc Furnace Plants

Considering the pivotal role of ferroalloys in the steel industry and the escalating global emphasis on sustainability (e.g., zero emissions and carbon neutrality), the demand for ferroalloys is anticipated to increase. However, the electric arc furnace (EAF) of ferroalloy plants generates substantial amounts of nitrogen oxides (NOx) because of the high-temperature combustion processes. Despite the substantial contributions of many studies on NOx prediction from various industrial facilities, there is a lack of studies considering the environmental condition of the EAF in ferroalloy plants. Therefore, this study presents a deep learning model for predicting NOx emissions from ferroalloy plants and further can provide guidelines for predicting NOx in industrial sites equipped with electric furnaces. In this study, we collected various historical data from the manufacturing execution system of electric furnaces and exhaust gas systems to develop a prediction model. Additionally, an interpretable artificial intelligence method was employed to track the effects of each variable on the NOx emissions. The proposed prediction model can provide decision support to reduce NOx emissions. Furthermore, the interpretation of the model contributes to a better understanding of the factors influencing NOx emissions and the development of effective strategies for emission reduction in ferroalloys EAF plants.

Numerical optimization and experimental investigation of renewable diethyl ether-fueled off-road CI engines for sustainable transportation

Cleaner energy generation on light-duty off-road diesel engines is one of the objectives of this study, which utilizes renewable diethyl ether (DEE) as a replacement for diesel to minimize the reliance on fossil diesel fuel. In an air-cooled single-cylinder diesel engine, various DEE mixes of 5, 10, 15, 20 and 25% were attempted and evaluated under varying loads (0, 25, 50, 75 and 100%) in an effort to enhance the performance and emission characteristics of agriculture diesel engines and lower the environmental effect of harmful emissions. The injection pressure was optimized using computational fluid dynamics (CFD), and performance and emission outcomes were optimized through response surface methodology (RSM) techniques. The experimental results found that brake thermal efficiency and specific fuel consumption were enhanced for a higher proportion of DEE blends under increasing loads. In addition, increasing the engine load decreased CO emissions while increasing carbon dioxide (CO2), hydrocarbon (HC), and nitrogen oxide (NOx) emissions. Reduced CO, NOx, and HC emissions and increased CO2 were realized in the blended fuel samples compared to those of pure diesel fuel at increasing DEE percentages. In summary, the utilization of a 15% DEE blend and the optimization of the injection pressure to 210 bar resulted in a notable improvement of 10% in thermal efficiency and a decrease in emissions by 5% when compared to other parameters.

NOx Emission Prediction of Diesel Vehicles in Deep Underground Mines Using Ensemble Methods

The mining industry faces persistent challenges related to hazardous gas emissions. Diesel engine-powered wheeled vehicles are commonly used during work shifts and are a primary source of nitrogen oxides (NOx) in underground mines. Despite diesel engine manufacturers providing gas generation data, mining companies need to predict NOx emissions from numerous load-haul-dumping (LHD) vehicles operating under dynamic conditions and not always equipped with gas sensors. This study focused on two ensemble methods: bootstrap aggregation (bagging) and least-square boosting (boosting) to predict NOx emissions. These approaches combine multiple weaker statistical models to yield a robust result. The innovation of this research is in the statistical analysis and selection of LHD vehicles’ working parameters, which are most suitable for NOx emission prediction; development of the procedure of source data cleaning and processing, model building and analyzing factors, which may influence the accuracy; and the comparison of two ensemble methods and showing their advantages and limitations for this specific engineering application, which was not previously reported in the literature. For datasets obtained from the same LHD vehicle and different operators, the more efficient bagging method gave a coefficient of determination R2 &gt; 0.79 and the RMSE (root mean square error) was under 30 ppm, which is comparable with the measurement accuracy for transient regimes of physical NOx sensors available in the market. The obtained insights can be utilized as input for mine ventilation systems, enhancing mining transport management, reducing workplace air pollution, improving work planning, and enhancing personnel safety.

The Experimental Investigation of the Effects on the Combustion, Performance, and Emission Characteristics of an RCCI Engine Using Methanol/Diesel Fuel

Reactivity-controlled compression ignition (RCCI) combustion is considered one of the most promising low-temperature combustion (LTC) concepts aimed at reducing greenhouse gases for the transportation and power generation sectors. RCCI combustion mode is achieved by combining different fuel types with low and high temperatures. The aim of this study is to investigate combustion characteristics and reduce nitrogen oxide (NOx) and carbon dioxide (CO2) emissions. In this experimental study, the effects of the RCCI strategy using methanol/diesel fuel on combustion characteristics (ignition delay, combustion duration), engine performance (brake-specific fuel consumption and brake-specific energy consumption), and emissions were examined in a four-cylinder, turbocharged, dual-fuel engine. The experiments were conducted at a constant speed of 1750 rpm at partial loads (40 Nm, 60 Nm, 80 Nm, and 100 Nm). The test results obtained with diesel fuel were compared with the test results obtained with methanol at different mass flow rates. When the results were examined, the minimum ignition delay (ID) occurred at 40 Nm torque, 5.63 crank angle (CA) with M12 fuel, while the maximum ID occurred with M26 fuel at 80 Nm torque, showing an increasing trend as engine load (EL) increased. The highest combustion time (CD) was achieved with M26 fuel at 100 Nm torque, whereas the lowest was achieved with the same fuel (M26) at 40 Nm. While the minimum brake-specific fuel consumption (bsfc) was 45.9 g/kWh for conventional diesel fuel at 40 Nm, the highest bsfc was 104.88 g/kWh for 100 Nm with M26 fuel. Generally, bsfc tends to increase with increasing load. Brake-specific energy consumption (bsec) had the lowest value of 1950.58 kJ/kWh with conventional diesel fuel at 40 Nm and the highest value of 4034.69 kJ/kWh with M26 fuel at 100 Nm. As the methanol content increased, significant improvements were observed in (NOx) and (CO2) emissions, while hydrocarbon (HC) and oxygen (O2) emissions increased as well. Smoke emissions decreased at low loads but tended to increase at high loads.

A study on nitrogen oxide emission prediction in Taichung thermal power plant using artificial intelligence (AI) model

In recent studies, artificial intelligence models have been developed for the prediction of nitrogen oxide emissions from thermal power plants. This research utilizes an artificial intelligence prediction model with more coal input features than boiler features, including volatility, ash content, sulfur content, fixed carbon, total moisture, calorific value, grinding rate, fuel ratio, coal feeding rate, boiler efficiency, total air volume, and excess air volume. The paper delves into the importance analysis of input features for artificial intelligence models. Moreover, feature importance analysis is not only a prerequisite for predicting nitrogen oxide emissions but also a study providing insights into model performance. An artificial neural networks (ANN) regression model is employed to predict nitrogen oxide emissions, and the results demonstrate that the number of feature importance significantly impacts model performance. The best model performance is achieved with eight specific input features. Finally, after the training and validation processes, the ANN model yields the optimal coefficient of determination (R2) value.

The individual tubular low-toxic combustion chamber

BACKGROUND: intensive works in improvement and development of microturbine power plants for energy and transport continues worldwide. These works are still relevant due to near-to-zero emissions of microturbines, as well as due to the fact that microturbines efficiency can be increased up to 50% and above, which opens the potential to compete with well-known power plants in the foreseeable future, including in terms of efficiency. Therefore, the work on the study of a low-toxic combustion chamber for a microturbine seems relevant as well. AIM: Сomputational and experimental study of an individual tubular low-toxic combustion chamber of a 50 kW microturbine with an increase in pressure at the inlet to the chamber. METHODS: The description of the experimental facility for combustion chamber testing and the results of its experimental study are given. A sufficient convergence of the experimentally obtained parameters of the combustion chamber with the parameters obtained from the simulation modeling of flow and combustion in the combustion chamber was obtained. RESULTS: In the course of the calculated and full-scale studies, hydraulic losses, nitrogen oxide emissions, and temperature unevenness at the outlet of the combustion chamber with increasing air pressure at its inlet were determined. CONCLUSIONS: The calculated study showed a significant effect of an increase in air pressure from 3 to 3.5 bar at the entrance to the combustion chamber on its main parameters. Thus, hydraulic losses have more than doubled and nitrogen oxide emissions have increased almost 1.3 times. The conducted experimental study of the combustion chamber generally confirmed the results of mathematical modeling and thereby tested the computational model used. Thus, the discrepancy in the experimentally and computationally obtained values of relative pressure losses in the combustion chamber does not exceed 15%, and in emissions of nitrogen oxides 7%.

Effect of ceria–silica-based synthesized catalyst in a CI engine exhaust system operating with plastic oil blend

This study investigates the impact of ceria–silica (Ce–Si)-based catalyst integrated in the catalytic converter (CC) on the compression ignition (CI) engine's exhaust manifold. The synthesis catalyst, Ce–Si was developed with the solvothermal method and aged for 4 h at 55°C. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, energy dispersive X-ray spectroscopy and transmission electron microscopy analyses were carried out to conclude the synthesis of the catalyst. The catalyst performance of the CC was tested for the emission behavior of nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbon (HC) and smoke. A custom-built CC was installed on the test engine's exhaust manifold. The synthesis catalyst was installed in the engine exhaust route of the stationary single-cylinder diesel engine to conduct the study. To determine the effect of the synthesis catalyst on the exhaust manifold to test both diesel and DPB (B50) fuel with and without CC. Under maximum load conditions, the presence of CC reduced oxide of nitrogen and carbon monoxide emissions by 23% and 17%, respectively, compared to diesel. The synthesized aerogel catalyst has a low density and a high surface area relative to its volume. Ce–Si aerogel catalyst can be used to improve the conversion efficiency of nitric oxide (NO), unburned hydrocarbon and CO in the three-way CC.

Role of methane in ammonia combustion in air: From microscale to macroscale

Ammonia (NH3) has gained increasing recognition as a carbon-free fuel. To enhance NH3 combustion, reactive gases, like methane (CH4), are usually added to the combustion system. In this work, the role of CH4 in NH3 combustion is systematically studied. A series of reactive force field molecular dynamic (ReaxFF MD) simulations are implemented to investigate effects of CH4 addition on the consumption of NH3 and the yields of nitrogen oxides (NOx) from the atomic perspective: CH4 accelerates the consumption of NH3 by shortening the decomposition time of the first NH3 molecule and increasing the translational kinetic energy of the system; CH4 modifies the yield of NOx by complicating the elementary reactions and introducing additional intermediates. The fuel ratio of CH4 and NH3 between 0.5 and 1 is suggested for a cleaner and enhanced NH3 combustion. By summarising the findings from the latest publications and the present work, the role of CH4 in NH3 combustion is comprehensively analysed from the macroscale and microscale perspectives: CH4 accelerates the progress of NH3 combustion flame, activates chemical reactions, and aggravates NOx emissions at a low CH4 content. Taking the NH3/CH4 combustion as an example, this study provides an exclusive perspective to understand combustion phenomena from the microscale events to macroscale observations.

Air pollution, APOE genotype and risk of dementia among individuals with cardiovascular diseases: A population-based longitudinal study

Individuals with cardiovascular disease (CVD) are particularly vulnerable to dementia, but it remains unclear whether air pollution exposure links with higher risk of dementia among those with CVD. The data were derived from the UK Biobank study (UKB). Dementia-free participants with CVD at baseline were included. Air pollution exposure was assessed through land use regression models, including particulate matter (PM2.5, PM2.5-10, and PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOX). A Cox proportional hazards model was used to investigate the associations between air pollution exposure and incident dementia among individuals with CVD. Air pollution was associated with dementia among individuals with CVD, and the hazard ratios of dementia associated with each interquartile range (IQR) μg/m3 increase in air pollution were 1.07 (95% CI: 1.02, 1.12) for PM2.5, 1.10 (95% CI: 1.04, 1.15) for PM10, 1.08 (95% CI: 1.03, 1.14) for NO2 and 1.05 (95% CI: 1.00, 1.09) for NOx. Associations between air pollution and all-cause dementia were found to be significant among individuals with hypertension. Adverse effects of air pollution were also observed for Alzheimer's dementia (AD) and vascular dementia (VaD), with a higher effect for AD. Observed associations remained similar in subgroups of APOE ε4 carriers and noncarriers, although there was a higher risk difference across different air pollution concentration among these individuals carrying APOE ε4. Air pollution emerges as a critical risk factor for dementia among individuals with CVD, regardless of genetic susceptibility indicated by the APOE genotype. Notably, individuals with hypertension might be susceptible to the adverse effects of air pollution, leading to a higher incidence of dementia. Understanding these impacts on dementia among individuals with CVD may promote better targeted prevention and clinical management strategies.