Search Results (951)

Multi-component solid waste combustion can recover energy and reduce the difficulty of waste classification, but variable solid composition complicates the reduction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), which has been paid attention to by the international community. Therefore, this paper comprehensively elaborates on the application characteristics of multi-component solid waste, analyzes the current situation of its source-controlling of generation and emission, and summarizes the source inhibition of PCDD/Fs emission and the research methods of PCDD/Fs in terms of three aspects: PCDD/Fs degradation technology, quantum chemical analysis method, and new regulation technology. The PCDD/Fs degradation technology includes photocatalytic degradation technology, metal catalytic degradation technology, and catalytic degradation technology under high temperature conditions. Quantum chemical analysis methods include physical adsorption and desorption phase catalytic synthesis and degradation and heterogeneous catalytic synthesis and degradation. New control technologies include solid waste control technology, chemical looping combustion (CLC) technology, and flow field simulation control technology. The technology of PCDD/Fs degradation is an important aspect in further optimizing the conditions of source inhibition of PCDD/Fs. Calculating the energy barrier of formation and degradation from the perspective of quantum chemistry is an effective method for analyzing the migration and transformation of dioxin precursors. Furthermore, exploring the new regulation technology is also the new research direction for inhibiting and controlling the source of PCDD/Fs. Full article

Coal fires are a significant source of greenhouse gas emissions and ecological pollutants, yet their emission characteristics and carbon accounting remain poorly constrained. To reveal the pollutant generation characteristics and carbon emission levels of the typical underground coal fire area in Sulabulak, Xinjiang, this study integrated laboratory simulation, multi-source remote sensing inversion, and in situ field monitoring. Thermogravimetric analysis, a high-temperature tube furnace, HSC thermodynamic simulation, and multi-source remote sensing data from Landsat-8/9 and Sentinel-1A were employed to investigate the gaseous products and heavy metal migration mechanisms at different combustion stages, and to delineate the spatial extent of different combustion states in the fire area. A coal loss model was then constructed by coupling experimentally determined carbon emission factors with remote sensing-derived areas and was compared with an emission flux model based on field measurements. The results show that the coal oxidation process proceeds through three distinct stages, with indicator gas ratios (CO₂/CO and C₂H₄/C₂H₆) serving as effective indicators for combustion state identification. Heavy metal partitioning is governed by elemental volatility and redox conditions: As and Se partition predominantly into the gas phase, while Zn becomes enriched in fly ash. Remote sensing time series analysis documents continuous fire expansion accompanied by progressive surface subsidence. By cross-validating the indirect coal loss model (constrained by remote sensing area) against the direct emission flux model (constrained by field measurements), we estimate the current annual GHG emission of the Sulabulak fire area at approximately 0.65 × 10⁴ t CO₂ equivalent. This study proposes a coupled “micro-experiment–macro-remote sensing–field measurement” approach for carbon emission accounting, providing reliable data support for environmental pollution control and the development of carbon inventories for coal fires in arid regions. Full article

The new Euro 7 standard will be the first legislation to limit the emissions produced by an automotive brake system. This has caused brake manufacturers to seek radical solutions to reduce the emissions generated from conventional grey cast iron (GCI) friction brakes. The regenerative braking system of electric vehicles (EVs) will require the friction brakes to be used less frequently than for an internal combustion engine vehicle. This may lead to a build-up of corrosion products on the friction surfaces that may not only affect the performance and service life of the GCI friction brake but also increase wear particle emissions when braking. Plasma electrolytic oxidation (PEO) ceramic-coated aluminium alloy rotors could be an alternative solution to reduce the effects of corrosion, produce lower brake emissions and also improve the energy efficiency of the EV by reducing its unsprung mass. To understand the interrelation between brake rotor corrosion and particulate emissions, this study concentrates on quantifying wear particles from a PEO-coated Al6082 brake rotor, both before and after exposure to salt fog corrosion. The results are compared to those for a standard uncoated GCI rotor and for an aluminium metal matrix composite (MMC) rotor subject to the same braking and corrosion test cycles. It was found that the PEO brake rotor produced a higher steady-state coefficient of friction in both the uncorroded and corroded conditions than either the GCI or MMC rotor, but emitted fewer wear particles in the uncorroded state, apart from at the highest brake line pressure. In the corroded state, the PEO rotor produced far lower emissions than either the corroded GCI or MMC rotors across all brake line pressures. Full article

Modern pyrotechnic materials are evolving from conventional fuel–oxidizer mixtures toward function-oriented energetic systems designed for controlled ignition, light emission, gas generation, pressure output and thermal response. This review analyzes recent progress in pyrotechnic materials through oxidizer chemistry, thermal and kinetic behavior, study-normalized performance comparison and bibliometric mapping. Representative oxidizer families, including nitrates, perchlorates, chlorates, metal oxides, hybrid oxide–salt systems, high-nitrogen salts, halogen-oxo oxidizers and coordination nitrate complexes, are compared in terms of chemical role and functional output. Thermal data show that decomposition temperature, heat release and activation energy must be interpreted together, since lower activation energy can indicate either enhanced reactivity or degradation during aging. A study-normalized relative performance factor (RPF) was used to compare performance changes within individual publications. The strongest relative improvements were associated with oxide selection, particle-size reduction, hybrid oxidizer design and coupling of nanothermites with gas-generating components. Bibliometric mapping confirmed a shift toward metal-based energetic materials, nanothermites, gas generators, combustion diagnostics, color systems and pyrotechnic devices. These trends show that oxidizer chemistry, particle architecture and additive function are increasingly selected for defined pressure, gas, light or thermal outputs. Full article

Under high-Mach-number flight conditions, the combustion chambers of hypersonic vehicles encounter extreme thermal environments marked by unilateral heating, high-heat-flux density, and supercritical pressure. Traditional hydrocarbon fuel cooling often suffers from insufficient heat sinks, high-temperature cracking and coking blockages, making it difficult to meet long-endurance thermal protection requirements. Liquid metal, due to its extremely high thermal conductivity, wide liquid phase temperature range, low Prandtl number and electromagnetic pump driving capability, has become a key technology for breaking through the bottleneck of high-heat-flux thermal protection. Apart from the magnitude of heat flux, the heat-transfer time scale (such as the characteristic thermal response time of the wall and the fluid) is also crucial. During hypersonic flight, transient thermal loads can change within milliseconds, requiring rapid thermal response. Liquid metals, due to their high thermal diffusivity, have a shorter thermal diffusion time compared to hydrocarbon fuels. This review employs a systematic literature review of approaches using gallium-indium-tin alloy, GaInSn, focusing on three core directions: the flow and heat-transfer characteristics of liquid metals, the optimization of cooling micro-channels, and the application of thermal protection systems. It summarizes the research progress at home and abroad, compares and analyzes the performance differences and applicable scenarios of typical liquid-metal working fluids, and summarizes the advantages and disadvantages of existing models, structural designs, and system schemes. The research shows that liquid metals can significantly alleviate thermal stratification and eliminate coking, and deep, narrow, tree-shaped, and biomimetic micro-channels can effectively enhance heat transfer. The liquid-metal-fuel dual-channel waste heat recovery and thermoelectric power generation system has demonstrated engineering application potential. Currently, the field still faces key challenges, such as unclear heat-transfer mechanisms under extreme conditions, the lack of general heat-transfer correlation formulas, insufficient compatibility with high-temperature materials, poor miniaturization and vibration resistance of electromagnetic pumps, and low system integration. In the future, efforts should be focused on developing multi-field coupled heat-transfer models under extreme thermal environments using engineered micro-channel structures, corrosion-resistant materials, and lightweight electromagnetic pumps, promoting the research and development of integrated thermal protection, heating and power generation systems, and providing support for the development of advanced thermal management systems for hypersonic aircraft and aviation engines. Full article

Atmospheric PM₁₀ was investigated across Campania, southern Italy, during August 2024 to assess its elemental composition and probable sources. In total, 132 daily samples were collected at six ARPAC sites representing harbor, traffic, industrial, school, and regional-background conditions. PM₁₀ concentrations ranged from 2 to 72 µg m⁻³, with the highest and lowest values recorded at the traffic and background sites, respectively. Elemental composition was determined by particle-induced X-ray emission and complemented by SEM–EDS. Elemental-based Positive Matrix Factorization (PMF) resolved six profiles, tentatively assigned to S-rich secondary aerosol, Cl-rich marine aerosol, mixed combustion/industrial emissions, Cu-rich traffic emissions, Ca–Sr-rich road dust, and Pb–Zn-rich waste combustion. At the industrial site, the three anthropogenic profiles together represented 74% of the apportioned mass. Traffic-related, marine, and S-rich secondary aerosol represented 49%, 65%, and 30% at the traffic, harbor, and background sites, respectively. SEM–EDS identified representative irregular S–K-rich and Ca-rich particles, crystalline Na–Cl-rich particles, and fine spherical metal-rich particles. Conditional probability function and trajectory analyses indicated local and regional influences, including a possible secondary sulfate contribution from the Mount Etna region. As the PMF analysis relied exclusively on elemental data, these source assignments should be regarded as indicative rather than definitive. Full article

A key challenge facing modern society, fueled by the relentless growth in energy and food requirements, is meeting rising energy needs without exacerbating greenhouse gas emissions. Nevertheless, fossil fuel combustion remains the primary contributor to human-induced pollution. As environmental concerns intensify and fossil resources become increasingly scarce, there is a growing push within the research community to identify alternative energy carriers and to advance more sustainable, low-impact technologies. Thus, this review focuses on catalytic CH₄ decomposition (CDM) for hydrogen production over Ni-, Fe, and Co-metal-based catalysts. Fe-based catalysts have received considerable attention for CDM due to their low cost and environmental sustainability. Furthermore, a discussion of deactivation and regeneration, along with the identified reaction mechanisms of CH₄ decomposition over these catalysts, is presented. Full article

Dry reforming of methane (DRM) represents a promising route for the valorization of CO₂ captured from industrial emissions through high-temperature catalytic conversion. In this work, a LaMn_1−xNi_xO₃ perovskite catalyst (x = 0.25, 6 wt% Ni) was synthesized as a powder by solution combustion synthesis and subsequently deposited onto γ-alumina supports to obtain a structured catalyst. X-ray diffraction confirmed the formation of the perovskite structure, characterized by corner-sharing BO₆ octahedra with Ni substitution at the B-site. H₂-temperature-programmed reduction (H₂-TPR) revealed the reduction of Mn⁴⁺ and Mn³⁺ species to MnO, accompanied by the complete reduction of oxidized Ni species to metallic Ni over the investigated temperature range. Raman spectroscopy of the spent catalyst indicated negligible carbon deposition after DRM. Moreover, the Mn–O stretching band shifted from 657 cm⁻¹ in the fresh catalyst to 643 cm⁻¹ after reaction, consistent with changes in the manganese oxidation state associated with the collapse of the perovskite structure and the formation of MnO. During a 25 h stability test at 700 °C, the powdered LaMn_1−xNi_xO₃ catalyst achieved a CH₄ conversion of 75% at a WHSV of 60 L g⁻¹ h⁻¹. DRM tests performed with the structured catalyst confirmed the catalytic performance under larger-scale operating conditions and different reaction parameters, including temperature, residence time, and CH₄/CO₂ feed ratio, reaching CH₄ conversions of up to 94% at 800 °C. Full article

This study evaluates the effects of novel metal-based fuel additives on the combustion, thermal behavior, and emissions of a common-rail diesel engine. Two transition metal complexes, Bis-[N-(1,1′-biphenyl)-2-chlorobenzoylthioureato]nickel(II) (NiL₂) and cobalt(II) (CoL₂), were synthesized and utilized as diesel additives for the first time. Experiments were conducted on a 1.5-L, four-cylinder engine at 1750 rpm under three load conditions: 50, 75, and 100 Nm. The results demonstrated that 25 ppm of NiL₂ and CoL₂ altered the combustion kinetics. At medium loads, the additives increased maximum cylinder pressure by 3% and shortened ignition delay at low loads. Peak heat release and heat transfer rates improved by 4% and 7%, respectively. CoL₂ exhibited the most pronounced thermal effect, raising average in-cylinder gas temperatures by up to 4% at high loads. However, despite these thermodynamic changes, the additives did not yield any reductions in NO, HC, or CO emissions; in fact, emission levels were generally similar to or slightly higher than those of neat diesel. These findings suggest that while these specific complexes act as combustion modifiers that enhance in-cylinder thermal parameters, they do not offer significant advantages regarding emissions under the tested configurations. Full article

Due to its abundant active sites, the bimetallic zeolite imidazole framework ZnCo-ZIF-67 exhibits excellent catalytic performance on the key oxidant ammonium perchlorate in composite solid propellants. In addition, carbon fiber has been proven to promote the combustion of propellants due to its high thermal conductivity efficiency. In order to integrate the advantages of both, this study designed and prepared a novel composite catalyst, ZnCo-ZIF-67/CF, by a co-precipitation method. The thermal decomposition test demonstrated that the ZnCo-ZIF-67/CF composite exhibited significant catalytic activity. When the addition amount was 5 wt%, the high-temperature decomposition peak temperature of AP decreased significantly from 424.3 °C to 337.2 °C, and the combustion process was also significantly accelerated. Furthermore, analysis of the products of thermal decomposition gases revealed a significant increase in the proportion of N₂O in the catalyzed products to 55.7%, whilst the proportion of high oxidation state nitrogen-containing oxides such as NO₂ and NOCl decreased. This finding suggests that the highly dispersed metal active sites in ZnCo-ZIF-67/CF synergistically promote the decomposition reaction pathway of AP, leading to enhanced N₂O generation. This study proposes a novel approach for the development of efficient and stable AP decomposition catalysts, which has positive significance for the regulation of the combustion performance of propellants. Full article

The consistent increase in atmospheric CO₂ concentration, mostly driven by the global combustion of fossil fuels, is considered one of the primary contributors to the increasing severity of environmental problems, like climate change and global warming. Attending to this issue requires innovative strategies that transform CO₂ into a valuable resource. In this work, we report a sustainable and fully metal-free approach for the synthesis of cyclic carbonates via the direct coupling of CO₂ with epoxides, using natural sugars as readily available, non-toxic organocatalysts in combination with tetrabutylammonium iodide (TBAI) as a cocatalyst. Seven representative mono- and disaccharides were screened, employing styrene oxide as a model substrate under mild reaction conditions (80 °C, 20 bar CO₂, 2 h). Among them, D-xylose exhibited the best catalytic performance. The robustness of this catalytic system was further demonstrated through the efficient transformation of a wide range of terminal, internal, and biomass-derived epoxides into their corresponding cyclic carbonates with high yields and selectivity (up to 99%). Additionally, a set of computational simulations based on density functional theory (DFT) calculations was carried out to gain insight into the atomistic mechanisms involved in this chemical transformation. We identified that the hydroxyl groups of the sugar catalyst play a pivotal role in activating the epoxy ring-opening process, leading to cyclic carbonate formation. This bio-inspired strategy provides a green, cost-effective, and scalable pathway to produce key precursors for organic chemistry, contributing to the development of a circular carbon economy and the advancement of sustainable chemistry. Full article

A comparative compositional screening of combustion behavior and phase formation during self-propagating high-temperature synthesis in B₂O₃–Al–C and B₂O₃–Mg–C mixtures was performed under the same open-air laboratory conditions. Twelve strongly carbon-rich formulations were examined. These formulations were not intended to reproduce the target stoichiometric reactions and are interpreted as an empirical screening matrix rather than as optimized stoichiometric compositions. In the individual SHS runs, the Mg-containing formulations produced higher recorded maximum apparent local combustion front temperatures and estimated apparent average front propagation velocities than the Al-containing formulations. Because each formulation was tested only once, these observations do not establish reproducible differences between the two systems. Qualitative X-ray diffraction analysis identified Al₂O₃, Al₂₀B₄O₃₆, Al₄B₂O₉, and residual Al in the aluminothermic products. MgO, Mg₂B₂O₅, and Mg₃B₂O₆ were identified in the magnesiothermic products. Weak reflections attributable to B₄C were observed in selected compositions, whereas oxides and metal borates were the principal crystalline phases identified in both systems. This result indicates that the carbide-forming pathway was competitively disadvantaged under the investigated open-air SHS conditions. Thermodynamic calculations for the idealized reactions showed that the relative standard driving force depended on temperature and the phase states of the reactants and products. The final phase assemblages indicate competition between carbide formation and the formation of stable oxide and borate phases. Atmospheric oxidation may also have contributed to the oxide-rich products. The results provide a descriptive comparison of the two investigated formulation sets and identify compositional patterns associated with limited B₄C formation under open-air SHS conditions. Full article

Improving gasoline octane quality is essential for modern spark-ignition engines, as increased knock resistance supports better efficiency, optimized combustion, and reduced fuel consumption. Environmental concerns have increased the demand for cleaner organic alternatives instead of conventional metallic octane boosters. This study evaluated selected organic octane improvers for commercial gasoline fuels, focusing on isopropanol (IPA), N-ethylaniline (NEA), and their binary blends. Fuel samples were prepared by controlled dosing of additives into base gasoline, followed by homogenization and determination of octane number using a portable fuel analyzer. Both additives increased gasoline octane rating, but their effectiveness depended on chemical type and dosage. NEA showed stronger octane-enhancing performance, whereas IPA provided a moderate improvement and potential combustion benefits associated with oxygenated fuel components. The investigated IPA–NEA binary blends increased the research octane number by up to 3.5 units at 3 vol.% additive concentration. Engine bench testing demonstrated reductions in CO emissions of up to 60%, in HC emissions of up to 40.8%, and in fuel consumption of up to 4.7% under selected operating conditions. Distillation characteristics remained within acceptable gasoline quality limits, indicating that the investigated additives did not adversely affect fuel volatility. Full article

To characterize heavy metal accumulation, potential sources, and source-specific ecological risks in farmland soils of the Ningxia Yellow River Irrigation Area, 537 topsoil samples were analyzed for As, Hg, Cd, Pb, and Cr. positive matrix factorization (PMF) was coupled with the potential ecological risk index to quantify source-specific mass and ecological risk contributions. Cd and Hg showed the strongest enrichment relative to regional background values, with mean concentrations of 2.38 and 2.02 times the respective background values. PMF resolved four factors interpreted as an agricultural input-related source, a parent material-dominated natural source, an urban industrial- and combustion-related atmospheric deposition source, and a Yellow River alluvial–hydrological natural background source. The mean potential ecological risk index calculated from PMF reconstructed concentrations was 168.45, closely matching the observed value of 168.77. Source-specific mass and ecological risk contributions were clearly decoupled: the two natural source factors contributed 71.19% of the modeled heavy metal mass but only 24.21% of the ecological risk, whereas the two anthropogenic source factors contributed 28.81% of the mass but 75.80% of the risk. The atmospheric deposition and agricultural input-related sources contributed 47.27% and 28.53% of the ecological risk, respectively. Site-level bootstrap resampling and alternative allocation procedures retained the source risk ranking. These findings indicate that risk-based management should prioritize Hg-related atmospheric deposition and Cd-related agricultural inputs rather than total heavy metal mass alone. Full article

The decarbonisation of the automotive sector requires product innovation, circular end-of-life management and energy-system transformation to be treated as interdependent strategic choices. This study proposes a decision-oriented life cycle assessment (LCA) framework for evaluating sustainable product innovation in sport utility vehicles (SUVs), focusing on how powertrain selection and post-consumer management support the low-carbon transition. Six SUV powertrain technologies—petrol, diesel and CNG internal combustion engine vehicles (ICEVs), petrol plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs)—were assessed for 2025–2050 using ReCiPe 2016, IPCC 2021, Cumulative Energy Demand, CML-IA and Ecological Scarcity 2021. Landfilling and recycling scenarios were combined with fuel- and energy-cycle modelling, including well-to-tank (WTT) and tank-to-wheel (TTW) emissions and a Paris Agreement-compatible 2050 pathway. Recycling generally outperformed landfilling, reducing greenhouse gas emissions by 26–35%, cumulative energy demand by 28–59%, carcinogenic air emissions by 27–43% and heavy-metal impacts on soil by 62–80%, although eutrophication revealed category-specific trade-offs. BEV and FCEV configurations were particularly sensitive to material recovery and energy-supply decarbonisation, whereas ICEV impacts remained dominated by fuel use. The findings show that sustainable SUV design requires strategic alignment of product architecture, circular supply chains, recycling technologies and low-carbon energy policy. Full article