High-temperature Combustion Processes Research Articles

Within-city spatial variations in PM2.5 magnetite nanoparticles and brain cancer incidence in Toronto and Montreal, Canada.

Magnetite nanoparticles are small, strongly magnetic iron oxide particles which are produced during high-temperature combustion and friction processes and form part of the outdoor air pollution mixture. These particles can translocate to the brain and have been found in human brain tissue. In this study, we estimated associations between within-city spatial variations in concentrations of magnetite nanoparticles in outdoor fine particulate matter (PM2.5) and brain cancer incidence. We performed a cohort study of 1.29 million participants in four cycles of the Canadian Census Health and Environment Cohort in Montreal and Toronto, Canada who were followed for malignant brain tumour (glioma) incidence. As a proxy for magnetite nanoparticle content, we measured the susceptibility of anhysteretic remanent magnetization (χARM) in PM2.5 samples (N = 124 in Montreal, N = 110 in Toronto), and values were assigned to residential locations. Stratified Cox proportional hazards models were used to estimate hazard ratios (per IQR change in volume-normalized χARM). ARM was not associated with brain tumour incidence (HR = 0.998, 95% CI 0.988, 1.009) after adjusting for relevant potential confounders. Although we found no evidence of an important relationship between within-city spatial variations in airborne magnetite nanoparticles and brain tumour incidence, further research is needed to evaluate this understudied exposure, and other measures of exposure to magnetite nanoparticles should be considered.

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.

ReaxFF molecular dynamics simulations of methane clathrate combustion.

Understanding the ignition and dynamic processes for the combustion of hydrate is crucial for efficient energy utilization. Through reactive force field molecular dynamics simulations, we studied the high-temperature decomposition and combustion processes of methane hydrates in a pure oxygen environment. We found that at an ignition temperature of 2800K, hydrates decomposed from the interface to the interior, but the layer-by-layer manner was no longer strictly satisfied. At the beginning of combustion, water molecules reacted first to generate OH•, followed by methane oxidation. The combustion pathway of methane is CH4→CH3•→CH3O•→CH2O→HC•O→HCOO•→CO(CO2). During the combustion process, a liquid water layer was formed between melted methane and oxygen, which hindered the reaction's progress. When there is no heat resistance, oxygen will transform into radicals such as OH• and O•, which have faster diffusion rates, allowing oxygen to conveniently cross the mass transfer barrier of the liquid water layer and participate in the combustion process. Increasing the amount of OH• may cause a surge in the reaction. On the other hand, when significant heat resistance exists, OH• is difficult to react with low-temperature hydrate components, but it can transform into O• to trigger the oxidation of methane. The H• generated has a sufficient lifetime to contact high-temperature oxygen molecules, converting oxygen into radicals that easily cross the water layer to achieve mass transfer. Therefore, finding ways to convert oxygen into various radicals is the key to solving the incomplete combustion of hydrates. Finally, the reaction pathways and microscopic reaction mechanisms of each species are proposed.

ML-assisted optimization method for the prediction of 3-dimensional fractal structures from microscopic images

Aggregated aerosol particles released from high temperature processes and combustion processes are often described as quasi-fractal aggregates, where the shape of these particles is represented by the scaling law. A detailed understanding of the morphology is quite important as various properties are strongly dependent on the particle shape. Electron microcopy based image analysis is the most commonly used technique to visualize and study the morphological features. In this study, we propose a machine learning (ML)-assisted retrieval method where ML techniques are combined with optimization algorithms to predict the morphological features and the corresponding 3-dimensional structures from microscopic images. The proposed algorithm is comprehensively tested with “synthetic” images as well as Transmission Electron Microcopy images. Various ML models, including Linear regression, Artificial Neural Network, K-nearest neighbours, Random Forest regression, and XGBoost are used for preliminary prediction of the morphological features (Number of monomers (N), fractal prefactor (kf) and fractal Dimension (Df)). These are used to narrow down the search space in the optimization algorithms. Random Forest and XGBoost methods achieved approximately 0.96 R2 score for N, 0.85 for Df and 0.73 for kf. Multiple optimization methods, including PSO, JAYA, and JAYA-SA, were tested in the study. The method was tested across a wide range of parameters, including N (up to 500), Df (1.1–2.7), and kf (0.6–2.1), and the results are quite promising while comparing various 3-dimensional properties of the retrieved structures. The retrieved fractal parameters, N and Df, exhibited errors under 10%, and the predicted kf values were found within approximately 15% using the proposed method. Results also show that the 3-dimensional properties of the predicted structure are quite close to the structures used for testing the algorithm. The algorithm was also parallelized to improve the computational time. The results show that the predicted fractal parameters and the retrieved 3-dimensional structures are quite similar to the structures used for testing across a wide range of particle morphologies. The incorporation of ML models has significantly improved the accuracy and computational speed, compared to the existing retrieval techniques.

Thermal Destruction of Waste and the Impact of the Presence of Cl and S in Waste on the Emissions of Cu, Ni, and Pb and Their Immobilisation in the Ash Residue

This study addresses the pressing environmental problem of the emissions of ecotoxic heavy metals from high-temperature waste combustion processes, including incineration and pyrolysis. Such emissions pose a serious threat to ecosystems and human health. This study investigated the behaviour of the heavy metals Cu, Ni, and Pb during the combustion of various waste materials such as plastic waste, pharmaceutical waste, and pesticide waste. To limit the release of heavy metals into the exhaust gas stream, various additives were used: divanadium pentoxide (V2O5), borax (Na2B4O7), and their mixtures with calcium oxide (CaO). Additionally, this study examined the impact of the content of chlorine heteroatoms (Cl) in burned waste materials on the emission levels of Cu, Ni, and Pb. The findings shed light on the mobility of ecotoxic heavy metals in high-temperature waste incineration processes (1273, 1373 K) and offer insight into strategies to improve their immobilisation in grate residues. At a temperature of 1273 K, V2O5 with CaO reduced Pb emissions by ~65% for plastic waste and by ~40% for pesticide.

Geo-polymer concrete- a concrete for sustainable environment

The production of the cement concrete industry has grown in this modern world and is considered one of the major contributors to global pollution. The production of cement used as a binder in cement concrete requires a high-temperature combustion process which contributes to the increase of the amount of CO2 in the atmosphere leading to major threats to the planet such as climate change and depletion of natural resources. Many countries begin to impose carbon taxes as raw materials deplete over time. To reduce and eliminate greenhouse gas emissions, numerous studies have been conducted to develop an innovative and environmentally beneficial building material names Geo-polymer concrete (GC). It is vital to substitute cement with a by-product substance abundant in silicon and aluminium like red mud, fly ash (FA), rice husk ash (RHA), silica fume (SF), ground granulated blast furnace slag (GGBS), etc. activated by a high alkaline solution (AS) to connect coarse aggregates (CA), fine aggregates (FA), and other substance in GC for the purpose of making a progress in qualities of concrete and reduce natural resource uses. The current study focused on the impact of various factors such as the effect of superplasticizer, Na-OH molarity (8, 10, 12, 14 and 16M), and curing temperature (30-900C) on different mechanical characteristics such as workability, tensile and compressive strength of GC. Results obtained show that the higher strength is obtained with a molarity of 14M after both 7 and 28 days as with 16M excess Na+ ions lower the strength and affect the process of polymerisation. The curing temperature at 900C for all mixtures gives higher strength as compared to 600C which in return gives higher strength than 300C at 28 days of testing. The results also show that the addition of superplasticizer (1, 1.5, 2 and 3 % of mass of fly ash) improves the workability of geopolymer fresh concrete. In current research work, Naphthalene superplasticizer was used and its addition beyond 1.5% of the mass of fly ash improved workability but slightly decreased the strength of concrete. Its optimum value was found as 68.05KN/m2 at 900C curing temperature when 14M NaOH and 1.5% superplasticizer were added.

ВИЗУАЛИЗАЦИЯ ГОРЕНИЯ НАНОПОРОШКОВ МЕТАЛЛОВ СПРИМЕНЕНИЕМ ИМПУЛЬСНОГО И НЕПРЕРЫВНОГО ЛАЗЕРОВ ПОДСВЕТКИ

The work is devoted to the development of the method for high-speed imaging of high-temperature combustion processes using laser illumination. The object of visualization was a sample of aluminum nanopowder, which combustion temperature reaches 2500 K and is accompanied by a bright glow that varies in a wide range during combustion. It is demonstrated that laser illumination expands the capabilities of a high-speed imaging system and allows a more detailed study of the surface of samples compared to passive imaging by installing a neutral or band-pass filter in front of the high-speed camera lens. Various options for imaging with the installation of light filters with different transmission are considered. To monitor the surface of a burning material with a high-speed video camera in a wide temperature range of an object, it is proposed to use a low-power illumination from a continuous wave solid-state laser or a pulsed laser, as well as a beam expander for uniform illumination of the surface. The results of imaging using illumination from a solid-state laser with a wavelength of 532 nm and a copper bromide vapor laser with a wavelength of 510.6 nm are compared. It is shown that the output power of a solid-state laser of 200 mW with an illumination area diameter of 20 mm is sufficient to visualize “through the flame” the surface of a burning aluminum nanopowder at a low-temperature stage of combustion up to temperatures of ~1950 K. The uniform illumination of the surface can be ensured both by using a diffuser located directly near the sample, and with the use of a telescopic beam expander. Theoretical estimates and experimental results demonstrate that the illumination average power of 200 mW, regardless of the type of laser, is not enough to visualize the surface of a burning aluminum nanopowder at the high-temperature stage. The possibility of complete suppression of illumination during combustion with a temperature above 2500 K will appear when using an illumination laser with an average power of >3,35 W. The proposed illumination technique based on a solid-state laser has advantages in terms of reliability and simplicity compared to known systems based on copper or copper bromide vapor lasers.

Improving the thermophotovoltaic performance of a hydrogen-fueled planar combustor with four-corner inlets via partially inserting porous medium

Micro thermophotovoltaic (TPV) generator is a potentially efficient approach to achieve microscale fuel-to-electricity conversion with high-energy–density, high-efficiency, and small-scale portability, where micro combustor provides the high-temperature continuous combustion process as well as a heat source of thermal radiation. In this study, a hydrogen-fueled planar combustor with four-corner inlets by partially inserting porous medium is proposed and investigated by a three-dimensional numerical model of porous medium combustion with detailed reaction mechanism and local thermal non-equilibrium. The combustor performance with and without partially inserting porous medium under various inlet velocities Vin and equivalence ratios ϕ are compared and analyzed to reveal the inherent strengthening mechanism. Moreover, the effects of various porous parameters on the energy conversion performance are examined: the porosity ɛ, thermal conductivity ks, and porous medium filled volume. The results demonstrate that the inserted porous medium can significantly enhance combustion efficiency, combustor wall temperature and its uniformity, and the largest increase in mean wall temperature reaches 79.7 K at Vin = 9 m/s, resulting in a 35.8 % increase in micro-TPV system efficiency. As ɛ and ks decrease, the combustor energy conversion performance increases while the temperature uniformity decreases. A moderate channel width L = 2.0 mm is good for further improving temperature uniformity and energy conversion efficiency. This study paves the way for the improvement of efficient, practical, and portable microscale generators.

The role of cool-flame fluctuations in high-pressure spray flames, studied using high-speed optical diagnostics and Large-Eddy Simulations

This work investigates the low- and high-temperature ignition and combustion processes, applied to the Engine Combustion Network Spray A flame, combining advanced optical diagnostics and large-eddy simulations (LES). Simultaneous high-speed (50 kHz) formaldehyde (CH2O) planar laser-induced fluorescence (PLIF) and line-of-sight OH* chemiluminescence imaging were used to measure the low- and high-temperature flame, during ignition as well as during quasi-steady combustion. While tracking the cool flame at the laser sheet plane, the present experimental setup allows detection of distinct ignition spots and dynamic fluctuations of the lift-off length over time, which overcomes limitations for flame tracking when using schlieren imaging [Sim et al.Proc. Combust. Inst. 38 (4) (2021) 5713–5721]. After significant development to improve LES prediction of the low-and high-temperature flame position, both during the ignition processes and quasi-steady combustion, the simulations were analyzed to gain understanding of the mixture variance and how this variance affects formation/consumption of CH2O. Analysis of the high-temperature ignition period shows that a key improvement in the LES is the ability to predict heterogeneous ignition sites, not only in the head of the jet, but in shear layers at the jet edge close to the position where flame lift-off eventually stabilizes. The LES analysis also shows concentrated pockets of CH2O, in the center of jet and at 20 mm downstream of the injector (in regions where the equivalence ratio is greater than 6), that are of similar length scale and frequency as the experiment (approximately 5–6 kHz). The periodic oscillation of CH2O match the frequency of pressure waves generated during auto-ignition and reflected within the constant-volume vessel throughout injection. The ability of LES to capture the periodic appearance and destruction of CH2O is particularly important because these structures travel downstream and become rich premixed flames that affect soot production.

Mineralogical and geochemical characteristics of coal from the Southeastern Qinshui Basin: Implications for the enrichment and economic value of Li and REY

Comprehensive assessment of the critical elements in coal is vital for understanding the geological processes affecting element enrichment allowing full utilization of coal in an economical and environmentally friendly manner. This study reports the latest data on the petrology, mineralogy, and coal geochemistry of the No. 15 coal seam in the southeastern Qinshui Basin. The enrichment mechanism of lithium (Li) and rare earth element and yttrium (REY) was analyzed. The result indicates that Li is significantly enriched (CC is 19.55) and mainly occurs in Ti-bearing minerals (e.g., clay minerals). REY mainly occurs in phosphate minerals, such as goyazite. The sedimentary provenance is the dominant factor influencing the mineralogical composition and elevated trace element concentrations of No.15 coal seam. Furthermore, hydrothermal fluids and marine environment also affected the mineral composition. After the high-temperature combustion process, the Li and REY have a higher enrichment ratio in the coal than that in the carbonaceous mudstone, parting the roof and floor samples. The REY contents of coal, roof and floor samples are higher than the marginal grade for industrial deposits. The evaluation results indicate the No. 15 coal seam has a potential to provide raw materials for the comprehensive processing and utilization of Li and REY.

Multiple-objective optimization of Jet Controlled Compression Ignition (JCCI) mode with dual-direct injection in a high-speed light-duty engine

Jet Controlled Compression Ignition (JCCI) mode with dual-direct injection of diesel and gasoline has been demonstrated by the engine experiments to provide an effective control on the combustion process without sacrificing the advantages on efficiency and emissions performance. The multiple-objective optimization of JCCI mode based on the 186FA engine at 75 % engine load with an engine speed of 3000 r/min was carried out in this research by the combination of Three-Dimensional (3D) Computational Fluid Dynamics (CFD) and Genetic Algorithm (GA). The simulation results indicate that the ignition timing and the combustion phasing can be effectively controlled by the jet-injection diesel, and the pre-injection gasoline mainly affects the combustion stage from CA50 to CA90. With the increase of the pre-injection energy ratio, higher initial in-cylinder temperature is required to ensure the engine performance. The optimal results present that JCCI mode can achieve high efficiency and low emissions simultaneously when the combustion phasing is at 5 ∼ 9 °CA ATDC. The low EISFC, NOx and soot emissions can be realized when SOIpre and SOIjet are retarded to −63 and −28 °CA ATDC, respectively, which prepares the appropriate premixed charge considering the equivalence ratio and reactivity. The comparisons of the typical cases reveal that the high-temperature combustion process gradually translates to the two-stage characteristics when the SOIjet retards from −27.77 to −18.88 °CA ATDC, the combustion duration is prolonged slightly and the in-cylinder temperature is decreased, resulting in the reduction of pmax by 0.42 MPa, NOx emissions by 0.07 g/kWh, associating with the lower heat transfer loss and exhaust loss. In addition, the NOx emissions in JCCI mode are mainly generated within the high-temperature combustion region of the jet-injection diesel spray target location.

Hydrocarbon pollution in the waters and sediments of the Kerch Strait

The results of studying the content and composition of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in the suspended particulate matter of surface waters and in the surface layer of bottom sediments in 2019–2021 in the Kerch Strait in comparison with earlier studies in other areas of the Black Sea (Theodosia Gulf, Tuapse area, Coastal waters of the Crimean Peninsula, Big Sochi, Central part of the Sea) are presented. Despite the high concentrations of aliphatic hydrocarbons (especially in the waters of the strait itself: 28–254 on average 87 μg/L. The highest content of aliphatic hydrocarbons was confined to the cross-section through the Kerch Strait. Accumulation of aliphatic hydrocarbons, as well as the suspended particulate matter, occurs in the western part of the Strait, which is associated with the predominant wind direction and coastal orography. The composition of alkanes did not correspond to the smooth distribution of homologues characteristic of oil. Their distribution was bimodal in most samples, which may indicate a mixed genesis of alkanes. Among the low-molecular-weight alkanes either even numbered autochthonous alkanes n-C16, C18, C22, arising during the microbial transformation of aliphatic hydrocarbons, or n-C17, indicating the inclusion of phyto- and zooplankton alkanes, prevailed. Despite the different sources of hydrocarbons input, the distribution of the total concentrations of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons basically coincided. Polycyclic aromatic hydrocarbons composition was dominated by fluoranthene and pyrene, which are formed in high-temperature combustion processes Low values of the Σnaphthalenes/Phen ratio (0.05–0.11) may indicate an insignificant inclusion of petroleum polyarenes.In contrast to suspension of surface waters, the highest content of hydrocarbons in the surface sediments was found not in the strait, but at stations in areas with aleurite-pelitic sediments, which is due to the pattern of currents in these areas and the higher sorption capacity of finely dispersed sediments. The average Corg content in July 2020, was 1.8 times lower (0.34%) than in September 2019 (0.63%), and aliphatic hydrocarbons, on the contrary, was 2.2 times higher (47 μg/g) than in April 2019 (21 μg/g). In surface sediments the maximum concentration of aliphatic hydrocarbons was established in July 2020 (233 μg/g), and the highest average content in July 2021 (58 μg/g). This area is also associated with higher concentrations of aliphatic hydrocarbons in the composition of Corg –≥1%. The composition of alkanes in surface sediments differed from their composition in suspension. The ratio of low-to-high molecular weight homologues (L/H = 0.08–0.54) was lower and the odd-to-even ratio (CPI = 1.19–4.58) was higher than in particulate matter. Due to the coarse composition of sediments, the content of polycyclic aromatic hydrocarbons in their surface layer was lower (0–631 ng/g) compared to other areas of the Black Sea. In their composition, along with fluoranthene and pyrene, methylated naphthalene homologues also belonged to the dominant compounds. Correlation analysis of individual polyarenes, as well as factor analysis, indicates their mixed genesis oil + pyrogenic, with the preference of the latter in most samples. The entry of pollutants into the marine environment increases the hydrocarbons content in water and bottom sediments, creating a modern hydrocarbon background.

The retention and speciation transformation mechanisms of chromium during bituminous coal combustion: Effects of inorganic minerals and combustion temperature

Coal combustion mainly releases chromium (Cr) as particulates and may oxidize Cr into toxic hexavalent forms. A series of combustion experiments combined with thermodynamic equilibrium calculations were used to study the speciation transformation behavior of Cr during the burning of a typical bituminous coal. Iron-bearing minerals and the combustion temperature were found to be vital for enriching Cr in ash and preventing Cr oxidation at high-temperature combustion process. During coal combustion, an increasing release trend of Cr versus the combustion temperature was observed. However, the degree of Cr oxidation didn't increase with the increased temperature. The fraction of Cr(VI) reached a maximum at 800°C, but gradually decreased as the combustion temperature rose to 1000°C. Further speciation study revealed that Cr was mostly presented in illite and pyrite in coal, which can be transformed into aluminosilicate glass and hematite. The ion-exchangeable, carbonate, and organic-bound Cr were easily released and also partly converted into less soluble residual form. At high combustion temperature (> 800°C), Fe2O3 exhibited a significant effect on Cr transformation and diminished the Cr(VI) ratios in coal ash. This was beneficial to the ash disposal or reutilization since Cr was retained as stable Cr (III) compounds in ash.

Seasonal variation and source apportionment of Oxygenated Polycyclic Aromatic Hydrocarbons (OPAHs) and Polycyclic Aromatic Hydrocarbons (PAHs) in PM2.5 in Seoul, Korea

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are of increasing interest due to their high toxicity. Thirteen particulate PAHs and ten particulate OPAHs were analyzed by Gas Chromatography/Mass Spectrometry (GC/MS) in atmospheric particulate matter with aerodynamic diameters less than or equal to a nominal 2.5 μm (PM2.5) for the period between May 2020 and January 2021 in Seoul, Republic of Korea. The mean concentration ten OPAHs (5.49 ± 2.40 ng/m3) was higher than that of thirteen PAHs (3.96 ± 3.36 ng/m3), respectively. The concentration of total OPAHs was high in winter (9.40 ± 2.50 ng/m3) and low in summer (3.58 ± 0.78 ng/m3), showing the same trend with PAHs (9.16 ± 3.30 ng/m3 in winter and 0.62 ± 0.15 ng/m3 in summer). When comparing this study results with the measurement results on 2006 in Seoul, PAHs concentration dropped by 68% while only 22% was reduced for OPAHs. It suggests either improvement of combustion technology, i.e., high temperature combustion process in the region or higher ambient oxidation reaction rates on 2020 than 2006. Major sources and their contributions of PAHs and OPAHs were identified based on correlation analysis and Positive Matrix Factorization (PMF) modeling. Two cases were carried. Case 1 is for source apportionment for PM2.5 and case 2 is for OPAHs and PAHs. The number of factors or sources in the two cases was determined as 7 and 4, respectively. The results of the PMF modeling using diagnostic ratios (DRs) in case 1 identified 7 factors; secondary nitrate (23%), secondary sulfate (21%), vehicles (20%), biomass burning (16%), coal combustion (12%), waste incineration (5%), and OPAHs (5,12-NAQ) emission-related (3%). The PMF modeling results in case 2 revealed 4 factors; vehicles (36%), coal combustion (30%), biomass burning (25%), and OPAHs (5,12-NAQ) emission related (9%). Significant correlation between OPAHs and indicators of primary emission sources, and high contribution from sources with emission characteristics implied that most sources of OPAHs were heavily influenced by primary emissions rather than secondary formation.

Physicochemical changes and sensory quality of liquid smoked milkfish nuggets

Liquid smoke method is an alternative to traditional smoking techniques, which aims to reduce polycyclic aromatic hydrocarbon (PAH) levels in the final product by degrading cellulose, hemicellulose, and lignin during pyrolysis of wood using a high-temperature combustion process. Research in liquid smoke is readily available in its application on raw fish product. However, less information is available in the ready-to-serve-product made of fish. Therefore, this study aimed to determine the effects of varying types and concentrations of liquid smoke on the sensory and proximate characteristics of milkfish nuggets, depending on the hardness, deformation, gel strength, organoleptic, and proximate testing. Parametric data were utilized for variance analysis and Tukey’s test. Non-parametric data, such as organoleptic and hedonic data, were analyzed using the Kruskall–Wallis test and the Mann–Whitney test. Varying types and concentrations of liquid smoke were found to significantly affect the hardness, deformation, gel strength, and protein and carbohydrate levels, as well as the organoleptic and hedonic properties on a 9-point scale starting with 1 to 9, with 1 as very unpleasant and 9 very pleasant (p < 0.05), but had no significant effect on the moisture or fat content of the resulting milkfish nuggets (p > 0.05). The best treatment was found to be 3 % re-distillation liquid smoke. Overall, the organoleptic and hedonic properties of milkfish nuggets processed with filtered and double-distilled liquid smoke were acceptable to be applied. Moreover, determining the type and concentration of liquid smoke is important consideration in the production of milkfish nugget in order to produce best physical and chemical qualities. Furthermore, milkfish nuggets were found to contain essential amino acids and fatty acids, which can be obtained when 3 % re-distilled liquid smoke was utilized to produce milkfish nuggets. This finding practically reveals the method and composition of milkfish nugget liquid, which was more likely to have the highest preference for consumers and may open the opportunity for the food industry to develop more derivative products from fish.

Mechanistic studies on the conversion of NO gas on urea-iron and copper metal organic frameworks at low temperature conditions: in situ infrared spectroscopy and Monte Carlo investigations

Nitrogen oxide (NOx) emissions from high-temperature combustion processes under fuel-lean conditions continue to be a challenge for the energy industry. Selective catalytic reduction (SCR) is possible using metal oxides and zeolites. There is still a need to identify catalytic materials that are efficient in reducing NOx to environmentally benign nitrogen gas at temperatures lower than 200 °C. Metal-organic frameworks (MOFs) have emerged as a class of highly porous materials with unique physical and chemical properties. This study is motivated by the lack of systematic investigations on SCR using MOFs under industrially relevant conditions. Here, we investigate the extent of NO conversion with two commercially available MOFs, Basolite F300 (Fe-BTC) and HKUST-1 (Cu-BTC), mixed with solid urea as a source for the reductant, ammonia gas. For comparison, experiments were also conducted using cobalt ferrite (CoFe2O4) as a non-porous counterpart to relate its reactivity to those obtained from MOFs. Fourier-transform infrared spectroscopy (FTIR) was utilized to identify the gas and surface species in the temperature range of 115–180 °C. Computational analysis was performed using Monte Carlo simulations to quantify the adsorption energies of different surface species. The results show that the rate of ammonia production from the in situ solid urea decomposition was higher using CoFe2O4 than Fe-BTC and Cu-BTC and that there was very limited conversion of NO on the mixed solid urea-MOF systems due to site blocking. The main conclusions from this study are that MOFs have limited ability to convert NO under low-temperature conditions and that surface regeneration requires additional experimental steps.

Disentangling multiple PM emission sources in the Po Valley (Italy) using honey bees

Particulate matter (PM) is a complex mixture of airborne chemical compounds commonly classified by their aerodynamic diameter. Although PM toxicity strongly depends on the morphology, chemical composition, and dimensions of particles, exposure limits set by environmental organisations only refer to the mean mass concentration of PM sampled daily or annually by monitoring stations.In this study, we used honey bees as sensors of airborne PM10 and PM2.5 in a highly polluted area of the Po Valley, northern Italy. Honey bees are an efficient sampler of airborne PM because, during flight and foraging activities, their pubescence promotes the accumulation of electrical charge on the body surface owing to air resistance, thus enhancing airborne PM attraction. Particles attached to the body of bees are readily accessible for physico-chemical characterisation using a scanning electron microscope coupled with X-ray spectroscopy (SEM/EDX). Our results demonstrate that residents in the study area are intermittently but chronically exposed to a well-defined spectrum of metal-bearing particles and mineral phases known to induce specific health outcomes.The morphology, size, and chemical composition of PM10 and PM2.5 detected on bees in the monitoring area were indicative of traffic, agricultural operations, and high-temperature combustion processes. The contribution of the A1 Milano-Bologna highway, local wheat and alfalfa cultivation, and the Parma incineration plant were clearly distinguishable. Our data also demonstrated that PM exposure levels may vary sharply throughout the year based on recurrent local activities.

Legacy persistent organochlorine pollutants and polycyclic aromatic hydrocarbons in the surface soil from the industrial corridor of South India: occurrence, sources and risk assessment.

Conversion of agricultural fields into the industrial corridor under the State Industries Promotion Corporation of Tamil Nadu Limited (SIPCOT) necessitated the investigation of soil-borne organic contaminants. This study is the first attempt to evaluate the occurrence of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in soils from Mambakkam and Cheyyar SIPCOT belt, along the residential, industrial and agricultural transects. Concentrations of Σ28PCBs, Σ16PAHs and OCPs were in the range 0.3-9ng/g, 33-2934ng/g and nd-81.4ng/g, respectively. Residential areas showed higher OCP concentrations than other site types, probably due to their frequent use in vector control programmes. DDT isomers and α-isomer of endosulfan showed low concentrations indicating past usage of these OCPs. Principal component analysis indicated that high-temperature combustion and industrial processes might be the major sources of high molecular weight PAHs, while low-temperature combustion processes might be responsible for low molecular weight PAHs. PCBs in soil were probably attributed to unaccounted combustion processes of e-waste in the region. Carcinogenic PAHs and Σ28PCBs were higher in the industrial sites. Mean Σ28PCBs at Mambakkam (4.8ng/g) was significantly higher (p < 0.05) than that at the incipient industrial corridor Cheyyar (2.7ng/g). Lower chlorinated PCBs (3-Cl and 4-Cl) amounted to more than half of Σ28PCBs in 75% of the sites. Total toxic equivalents (TEQs) of PAHs (total BaPeq) were found to be maximum in industrial areas. Maximum contribution to TEQs due to dioxin-like-PCBs was from PCB-157, followed by PCB-189.

Detailed measurements of transient two-stage ignition and combustion processes in high-pressure spray flames using simultaneous high-speed formaldehyde PLIF and schlieren imaging

This study investigates the low- and high-temperature ignition and combustion processes in a high-pressure spray flame of n-dodecane using simultaneous 50-kHz formaldehyde (HCHO) planar laser-induced fluorescence (PLIF) and 100-kHz schlieren imaging. The PLIF measurements were facilitated through the use of a pulse-burst-mode Nd:YAG laser, producing a 355-nm pulse-train with 300 pulses at 70 mJ/pulse, separated by 20-µs, in a 6-ms burst. The high-speed HCHO PLIF signal was imaged using a non-intensified CMOS camera with dynamic background emission correction. The acquisition rate of this HCHO PLIF diagnostic is unique to the research community, and when combined with high-speed schlieren imaging, provides unprecedented opportunity for analysis of the spatiotemporal evolution of fuel jet penetration and low- and high-temperature ignition processes relevant to internal combustion engine conditions. The present experiments are conducted in the Sandia constant-volume preburn vessel equipped with a new Spray A injector. The influences of ambient conditions are examined on the ignition delay times of the two-stage ignition events, HCHO structures, and lift-off length values. Consistent with past studies of traditional Spray A flames, the formation of HCHO is first observed in the jet peripheries where the equivalence ratio (Φ) is expected to be leaner and hotter and then grows in size and in intensity downstream into the jet core where Φ is expected to be richer and colder. The measurements demonstrate that the formation and propagation of HCHO from the leaner to richer region leads to high-temperature ignition events, supporting the identification of a phenomenon coined “cool-flame wave propagation” during the transient ignition process. Subsequent high-temperature ignition is found to consume the previously formed HCHO in the jet head, while the formation of HCHO persists in the fuel-rich zone near the flame base over the entire combustion period.

Effect of oxidative torrefaction on high temperature combustion process of wood sphere

The present work studies the effects of oxidative torrefaction (OT) (200–290 °C, 0–8 vol% O2) on the combustion process of wood sphere in a single particle combustor (SPC, 1226 °C, 3.0 vol% O2, wet basis), together with such effects on the yield, reactivity and morphology of the high temperature produced char. Increased torrefaction O2 concentration and temperature both result in higher char yield and prolonged combustion time, and the SPC char yield can be described by a linear regression equation (R2 = 0.85) as a function of the decreased mass yield caused by the OT process. The correlation (R2 = 0.83) between the low heating rate char yield (i.e., fixed carbon content) and the torrefaction mass yield is also validated against literature data, indicating that mass yield is a good indicator for both the OT and traditional inert torrefaction. The TGA analysis suggests that the char reactivity is significantly reduced by raised OT temperature up to 290 °C, while is only limited influenced by the increase in O2 concentration (up to 8 vol% at OT temperature of 260 °C). The NMR analysis of the OT wood and the SEM observation of the OT char produce from SPC show some evidences that OT result in a more cross-linked aromatic structure, which may hinder the volatile release in the subsequent pyrolysis and thereby lead to less porous char surface and a denser and heavier char particle.