Soot Particles Research Articles

A mathematical model of the dynamic viscosity dependence of motor oils on temperature, soot concentration, and its morphology

Objectives. A quick cold start of emergency and auxiliary power units based on diesel engines should be possible at any time without problems and in the shortest possible time. The condition of the engine oil is one of the most important factors influencing the smooth start-up of power plants. During diesel engine operation, engine oil accumulates soot in its composition, negatively affecting its rheological properties. The aim of this research is to develop a mathematical model to describe changes in the dynamic viscosity of motor oils as a function of temperature. This model will account for the concentration of soot and its morphology, based on the results of experimental studies.Methods. Standardly used motor oils for diesel engines M-14D2SE and M-5z/14D2SE were used as oil samples in the preparation of model mixtures. The dispersed phase of the suspensions comprised carbon black of the N110, N220, N330, and N220 grades, characterized by a dusty (nongranular) texture. The rheological properties of the samples were determined using a TA Instruments DHR-2 rotational rheometer. The experimental data was subjected to mathematical statistical processing, in order to obtain approximating dependencies.Results. The paper presents an analysis of the various approaches to the description of the rheology of suspensions and the results of experimental studies of the viscosity-temperature characteristics (VTCs) of model samples of oils containing soot. The extant models of the dependence of the dynamic viscosity of suspensions on temperature, volume concentration of the dispersed phase, particle size and shape are demonstrated to be inadequate for the description of the VTCs of motor oils containing soot. A model of the rheological properties of soot-oil suspensions is proposed in the form of a mathematical dependence of their dynamic viscosity on temperature, mass concentration of soot, material density and size of soot particles, characteristics of the shape and structure of primary aggregates and the ratio of the sizes of aggregates and molecules of the dispersion medium.Conclusions. It was demonstrated that a comprehensive description of the VTCs of engine oils containing soot necessitates the consideration of the structural characteristics of the primary aggregates of soot particles. A mathematical model of the VTCs of oils was developed. This model is based on the dependence of the dynamic viscosity of oils on temperature, mass concentration of soot, density of the particle material, degree of non-sphericity of aggregates, the ratio of the particle sizes of the dispersed phase (either aggregates orsingle particles of non-aggregated soot) and oil molecules, and on the structure ofsoot, characterized by adsorption of dibutyl phthalate.

Enhancing Catalytic Removal of Autoexhaust Soot Particles via the Modulation of Interfacial Oxygen Vacancies in Cu/CeO2 Catalysts.

The purification efficiency of autoexhaust carbon strongly depends on the heterogeneous interface structure between active metal and oxide, which can modulate the local electronic structure of defect sites to promote the activation of reactant molecules. Herein, the high-dispersion CuO clusters supported on the well-defined CeO2 nanorods were prepared using the complex deposition slow method. The formation of heteroatomic Cu+-Ov-Ce3+ interfacial structural units as active sites can capture electrons to achieve activation of the NO and O2 molecules. Among all of the synthesized catalysts, the Cu10/CeO2 catalyst exhibits superior catalytic performance (T50 = 351 °C) along with remarkable tolerance to H2O and SO2 in the removal of soot particles. Through a combination of comprehensive characterizations and density functional theory calculations, it is proposed that the interfacial Cu+-Ov-Ce3+ site, acting as an electron enrichment center, can capture electrons from the Cu d-band and Ce d/f-band to obtain high delocalized electron density, and then enhance the oxidation of NO to NO2, which plays a crucial role in the NOx-assisted catalytic mechanism for soot oxidation. This study presents a novel strategy for developing highly efficient catalysts that exhibit resistance to H2O and SO2, aimed at enhancing the removal of soot particles.

Noncatalytic Reduction of Nitrogen Oxide and Soot Inhibition during Cocombustion with Biotar: The Molecular Dynamics Modeling Approach.

Cocombustion with biomass tar is a potential method for NO reduction during fossil fuel combustion. In this work, the molecular dynamic method based on the reactive force field was used to study the NO reduction by phenol, which is a typical tar model compound. Results indicate that phenol undergoes significant decomposition at 3000 K, resulting in the formation of small molecular fragments accompanied by the generation of large molecular, network-structured soot particles. At higher temperatures (3500 K), the morphology of the soot produced from phenol decomposition undergoes a certain degree of change. It evolves from a two-dimensional network structure to a three-dimensional particulate structure. Soot particles are significant products of the thermal decomposition process of phenol. NO acts as an oxidant during the phenol decomposition process, significantly inhibiting the formation of soot particles during this process. Phenol also promotes the reduction of NO. The corresponding NO reduction ratios of NO are 52%, 76%, and 89% for 1500, 2000, and 2500 K respectively. CO, H2O, and N2 were the three most important reaction products during phenol-NO interaction. HNO is an important intermediate during the reduction of NO by phenol. The combination of the H radical and NO is the main route for HNO. It can be seen that HNO is quickly produced at the initial stage. The calculated activated energies for NO reduction and phenol oxidation are 30.47 and 50.85 kJ/mol, respectively.

Evaluation of soot particles from different-sized rapeseed oil flames: scientific focus on a traditional Japanese craft, Nara sumi

Nara sumi is a traditional Japanese craft, the skills and wisdom of which have been handed down through generations by artisans. Soot is a principal material determining sumi ink quality. Hand-made soot from rapeseed oil (lampblack) is still used in traditional Nara sumi instead of mass-produced carbon black. However, currently only one manufacturer continues to produce lampblack, and the artisan's production rules of thumb have not been scientifically studied. This study aims to clarify the effect of flame size variation on soot particle size, the most important rule of thumb in Nara sumi production. High-quality soot purportedly has a smaller particle size and can be generated from a smaller flame. We used three wick sizes to generate different sized flames and measured the particle size distribution of generated soot. The resulting soot particle size was found to increase as the flame increased. To additionally identify the flame area contributing to soot formation, a 2D analysis was conducted on the morphology and chemical state of soot collected from various heights within a rapeseed oil flame. The results show that soot formation progress is limited to the innermost zone of the flame, and only surface oxidation occurs in the middle zone and beyond. Soot transfer from the innermost to the middle zone was considered to be important in soot formation, based on both the morphology and chemical state changing rapidly and greatly at their boundary. These findings can help to preserve the knowledge for the traditional craft and Japanese cultural heritage.

Don't forget the trans: double bond isomerism radical-acetylene growth reactions affect the primary stages of PAH and soot formation.

In combustion, acetylene is a key species in molecular-weight growth reactions that form polycyclic aromatic hydrocarbons (PAHs) and ultimately soot particles. Radical addition to acetylene generates a vinyl radical intermediate, which has both trans and cis isomers. This isomerism can lead to profound changes in product distributions that are as yet insufficiently investigated. Herein, we explore acetylene addition to substituted trans-vinyl radicals, including potential rearrangement to cis structures, for eight combustion-related hydrocarbon radicals calculated using a composite method (G3X-K). Of these eight systems, the phenyl trans- and cis-Bittner-Howard HACA (hydrogen abstraction, C2H2 Addition) process, where acetylene successively adds to a phenyl radical via a β-styryl intermediate, is simulated using a unified Master Equation model. Including the trans-Bittner-Howard pathway changes the products significantly at all simulated temperatures (550-1800 K) and pressures (5.33 × 102-107 Pa), relative to a cis-only model. Typically, naphthalene remains the dominant product, but its abundance decreases at higher temperatures and pressures. For example, at 1200 K and 105 Pa, its branching ratio decreases from 78.5% to 62.9% when the trans pathway is included. At higher temperatures this decrease corresponds to the formation of alternative C10H8 isomers, including the cis product benzofulvene with 8% maximum abundance at 1200 K and 5.33 × 102 Pa, and E-2-ethynyl-1-phenylethylene, a trans product with 26% maximum abundance at 1800 K, with little pressure dependence. At higher pressures, our model predicts a range of C10H9 radicals, including resonance-stabilised radicals (RSRs). The impact of trans-vinyl radical chemistry in reactive environments means that they are essential to accurately describe combustion reactions and inhibit soot formation.

Black Carbon Nanoparticles in Atmospheric Aerosols: Update on Functional Groups

Aerosols are fine particles in the atmosphere produced by nature or man-made like fog, forest exudates, industrial emissions, biomass burning, and dust. Aerosols can change the earth's climate, and the formation of clouds, and may reduce the rain as they circulate in the atmosphere. Black carbon, also called soot is the dominant form of particles in the atmosphere which absorb light. They are fine particles and are smaller than dust and mold particles. Poly-aromatic hydrocarbons in soot particles result in substantial health complications even at small concentrations. Atmospheric pollution is an interesting subject as it is related to the problem of global warming. Particularly carbon aerosols can decide the condition of climate since the oxidation of these particles will result in the toxicity of atmospheric particulates. The processes involved in the atmosphere can be predicted through the analysis of these aerosols. Black carbon absorbs light of short wavelengths, and it enters into the stratosphere which causes climate change. The properties of black carbon obtained from various measurements provide information about the atmosphere's constituents. Raman spectroscopy is widely used for the identification of functional groups of atmospheric aerosols. The formation and properties of carbon aerosols obtained through these techniques will be used to explain the oxidation and particle-phase reactions of carbon aerosols. Carbon aerosols affect human health because of various factors such as chemical aging. In this review article, carbon nanoparticles present in the atmosphere, the analysis of those particles using Raman spectroscopy, and their implications on human health as well as climate change are discussed through various reports.

Transient Models of a Photophoretically Filtering Structure in the Stratosphere

The stratosphere has very little convection and tends to trap any dust and gases that enter this region from the atmosphere. This study suggests how dust and particles can be filtered from the stratosphere by a 2-plated parallel-walled infinite rotatable, levitating vertical/horizontal channel (preferably) perforated with holes which have pockets on the cooler upper wall for collecting particles. A movement of particles by light called photophoresis, is caused by the radiative warming layer of a sandwich structure. Collisions of gases with surface of structure and thermal gradients between the two thin plates will also deflect particles. Equations of momentum and energy are solved using an implicit finite difference scheme while exact solutions are presented for steady state dimensionless velocity, concentration and temperature for a fully developed flow. Heat and mass transfer characteristics of parameters like time are displayed graphically. Combined photophoretic and thermophoretic effect on water particles is negligible when compared to soot or dust particles Sc=600.

Effects of 1-Pentanol, Methyl Butyrate and Polyoxymethylene Dimethyl Ether on Soot Formation in Isooctane Inverse Diffusion Flames

ABSTRACT This paper investigates the effects of 1-pentanol, methyl butyrate (MB), and polyoxymethylene dimethyl ether (PODE3) additions on soot formation in isooctane inverse diffusion flames under oxygen-enriched combustion, with a particular emphasis on the physicochemical characteristics of soot particles. Isooctane was used as the baseline fuel, with 40% and 60% volumetric fractions of 1-pentanol, MB, and PODE3 added to evaluate the soot particle behaviors comparatively in the post-flame space, which were examined using quartz-based sampling followed by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The sooting tendency of isooctane flames was reduced with the addition of 1-pentanol compared to MB, which can be attributed to its lower molecular weight and higher H/C ratio. In contrast, the minimum average soot mass was observed with PODE3 additions, associated with its higher oxygen content. The results revealed that increasing amounts of 1-pentanol, MB, and PODE3 added to isooctane decreased fringe length, increased tortuosity, and reduced graphitization levels in the soot particles. However, the 40% PODE3/isooctane mixture resulted in shorter fringe length, smaller crystallite dimensions, and a lower degree of graphitization than 1-pentanol and MB additions. Therefore, TEM, HRTEM, XRD, Raman, and XPS analyses indicated that soot particles generated from a higher PODE3 ratio show a translucent film-like liquid morphology with a compact turbostratic structure, as evidenced by the shortest fringe length, highest tortuosity, smallest crystallite sizes, and a more amorphous nature with the least amount of graphitization.

Numerical Analysis of Soot Dynamics in C3H8 Oxy-Combustion with CO2 and H2O

Oxygen-enriched combustion is increasingly recognized as a viable approach for clean energy production and carbon capture, offering substantial benefits for boosting combustion efficiency and mitigating pollutant emissions, which makes it widely adopted in various industrial applications. Liquefied petroleum gas (LPG), predominantly consisting of propane (C3H8), is commonly utilized in numerous combustion systems, yet its emissions of soot particulates have raised considerable environmental concerns. This study delves into the combustion dynamics and soot formation behavior of propane, the principal component of LPG, under oxy-fuel combustion conditions, with the inclusion of H2O and CO2, utilizing both experimental techniques and numerical simulations. The results reveal that CO2 and H2O suppress soot formation through distinct mechanisms. CO2 decreases soot nucleation and surface growth by lowering flame temperature and H atom concentration, but it minimally enhances soot oxidation. H2O significantly reduces soot formation by chemically increasing OH radical concentration, thereby enhancing soot oxidation. A detailed decoupling analysis further shows that CO2’s influence is predominantly thermal and chemical, resulting in lower OH levels and an elongated flame shape. In contrast, H2O’s substantial thermal and chemical effects decrease flame height and promote soot reduction. These insights advance the understanding of soot formation control in oxy-fuel combustion, offering strategies to optimize combustion efficiency and minimize environmental impact.

The catalytic effect of chromium-doped ceria-praseodymium on soot oxidation activity and its kinetics.

Soot generated from the partial combustion of diesel significantly contributes to air pollution, and catalytic oxidation is currently an effective method for removing diesel soot particles. The chromium-doped ceria-praseodymium (Cr-CP) catalyst system is synthesized via solution combustion synthesis and evaluated for soot oxidation activity, with a subsequent kinetics study conducted. The XRD analysis of the catalysts indicated a decrease in crystallite size and increased lattice strain and reactive facet ratios for all Cr-doped CP samples. Raman analysis verified the existence of oxygen vacancy peaks in all chromium-doped CP catalysts. X-ray photoelectron spectroscopy (XPS) revealed the presence of adsorbed H2O or molecular water peaks in the O1s spectra for the 5 Cr-CP catalyst, which also exhibited a high concentration of surface Cr3+ ions. Thermogravimetric analysis (TGA) of soot oxidation indicated that 5 Cr-CP exhibited a superior T50 of 393 ± 2°C, mostly attributed to the presence of reducible surface Cr3+ ion species. Kinetic analysis was performed on all Cr-doped CP catalysts to assess the kinetic triplets: activation energy, pre-exponential factor, and reaction model. The activation energy was low (87kJmol-1, Ozawa method) for 15 Cr-CP, while the pre-exponential factor was higher for 5 Cr-CP (7.39 × 1010min-1). The Cr-CP catalyst system adhered to a power law, indicating a phase boundary-controlled reaction characterized by nucleation and growth mechanisms. The consistency between experimental and calculated curves confirmed that the developed catalysts adhered to the Avrami-Erofeev equation (Am) or the nucleation and growth model.

Soot particle morphology and polycyclic aromatic hydrocarbons formation molecular dynamics during diffusion combustion of three pentanol biofuels

Soot particles constitute a major pollutant in engine diffusion combustion, posing a serious threat to human health and the atmospheric environment. The employment of carbon-neutral biofuel, pentanol, in engines contributes to reducing soot emissions; however, its effectiveness is contingent upon the position of the OH functional group. This work investigated the soot morphology and microstructural parameters evolution of three pentanol isomers, and explored the influence mechanism of OH functional group positional isomerism on the entire process of PAHs formation at the atomic level. The results showed that the peak of primary particle size and soot volume fraction in pentanol flames showed a trend of 2-pentanol>3-pentanol>1-pentanol, and the initial formation time of soot in 1-pentanol flame is the latest, and the particle aggregate size is the smallest. The entire process of pentanol isomers soot formation can be divided into four stages: fuel pyrolysis forming initial ring, PAHs growing into initial soot, soot chain growth and structural evolution, soot morphology transformation and maturation. Among the three isomers, 2-pentanol has the fastest initial ring formation rate, the highest peak C-number in the largest molecule, and ultimately forms a more mature fullerene-like structure. 1-pentanol has the slowest initial ring formation rate, the lowest peak C-number in the largest molecule, ultimately forms a lower maturity layered structure. In terms of reaction pathways, H-atom abstraction and dehydroxylation reactions jointly dominate the initial decomposition pathway in 1-pentanol combustion, while in 2-pentanol, dehydroxylation becomes the main initial decomposition pathway due to the high stability of H atoms on β‑carbon. The dehydroxylation reaction tends to generate olefins, promoting the generation of C1-C4 hydrocarbon. The oxygen atom bonded on the α‑carbon site exhibits a stronger carbon fixation ability, and C1-C4 hydrocarbons are more inclined to participate in oxidation to form CO rather than promote the soot production.

Water vapor and soot spatial characteristics retrieve of axisymmetric optically-thin laminar diffusion flame based on visible and near-infrared multi-spectral light field imaging

The comprehension of the distribution of gaseous species and soot particles plays a pivotal role in investigating the combustion process of a flame. A highly effective method to accomplish this is by extracting visible and near-infrared emission information from flames. In this study, we present a novel near-infrared multi-spectral light field imaging model that enables the concurrent extraction of gas and soot property distributions within a flame. A synthetic test of ethylene diffusion flame is assessed using the proposed reconstruction method. The mole fraction of gaseous water, together with the flame temperature and soot volume fraction, are decoupled spectrally using near-infrared and visible wavelengths. The results demonstrate a reliably retrieved temperature range of 1400 K to 2050 K, accurately reconstructing the actual distributions of soot volume fraction and gaseous water mole fraction. Minor influences on the imaging results and property reconstruction are observed due to uncertainties arising from the reconstruction method, absorption function, reconstruction wavelength for H2O mole fraction, and signal-to-noise ratio. This study serves as a theoretical guide for the future development of practical near-infrared multi-spectral light field imaging techniques for rapid and robust flame diagnostic purposes related to soot and gas properties.

Enhanced oxidative potential and SO2 heterogeneous oxidation on candle soot after photochemical aging: Influencing mechanisms of different irradiation wavelengths.

Photochemistry plays a significant role in the atmospheric aging processes of soot. However, the physicochemical properties and changes in environmental and health effects of soot particles from sacrificial sources after photochemical aging remain unclear. The reaction mechanisms of soot under different irradiation wavelengths require further investigation. In this study, candle soot from sacrificial sources was subjected to photochemical aging using ultraviolet (UV) and visible light. The experimental results of oxidation potential (OP) and heterogeneous oxidation of sulfur dioxide (SO2) indicated that both UV and visible light promoted the photooxidation of candle soot, leading to significant increases in oxygen-containing functional groups, environmentally persistent free radicals, and negative charges on soot surfaces. After photochemical aging, candle soot exhibited higher OP values and enhanced SO2 oxidation and sulfate formation. UV light had a stronger photooxidation ability on candle soot than visible light. Mechanistic analysis revealed that the photochemical aging mechanisms driven by reactive oxygen species were different under these two wavelengths. Photosensitive aging induced by organic carbon under UV light was stronger than the photocatalytic oxidation induced by element carbon under visible light. Our research findings provided new insights into the photochemical aging mechanisms and health impacts of soot.

Candle soot nanoparticles covered femtosecond laser-induced graphene toward multifunctional wooden houses

Laser-induced graphene (LIG) is an innovative material that can be used in the construction of smart wood houses due to its high electrical and thermal conductivity. However, potential practical challenges such as fire hazards, and the complexity of daily cleaning are limitations in such an application. In this study, we utilized femtosecond laser direct writing technology to create femtosecond laser-induced graphene (FLIG) on flame retardant cork. The FLIG surface was then coated with multi-scale candle soot particles to incorporate carbon black (CB-FLIG) superhydrophobic surface properties. Here we demonstrate CB-FLIG as a raw material for electronic components in multifunctional wooden houses. The infrared emissivity of the CB-FLIG surface was as high as 97.2 % and the electric heating performance was good. As such, it can be used as an electric heater in the winter, and we achieved room temperature control at a comfortable 24.9 °C with 4 V voltage in a model house. Also, the water contact angle was 151.2°, giving CB-FLIG self-cleaning properties. Ultimately, we demonstrate the application of CB-FLIG in the field of smart home components such as electrical wiring, electric heaters, fire protection, and self-cleaning, increasing functionality while reducing the need for routine maintenance. This study lays a robust foundation for state-of-the-art devices within smart timber houses and significantly propels the development of versatile, interconnected wooden dwellings.

Soot Particle Emissions: Formation and Suppression Mechanisms in Gas Turbines

This article reports on field tests devoted to the emissions of particles from gas turbines (GT) and more particularly to the formation of soot and its suppression by fuel additives. These field tests involved four heavy-duty gas turbines used as power generators and equipped with air atomization systems. These machines were running on natural gas, No. 2 distillate oil, heavy crude oil and heavy fuel oil, respectively. The GT running on natural gas produced no soot or ash and its upstream air filtration system in fact allowed lower concentrations of exhaust particles than those found in ambient air. Soot emitted when burning the three liquid fuels (No. 2 distillate; heavy crude oil; and heavy oil) was effectively reduced using fuel additives based on iron(III), cerium(III) and cerium(IV). Cerium was found to be very effective as a soot suppressant and gave rise to two surprising effects: cerium(III) performed better than cerium(IV) and a “memory effect” was observed in the presence of heat recovery boilers due to the deposition of active cerium species. All of the reported results, both regarding natural gas emissions and soot reduction, are original. A review of the soot formation mechanisms and a detailed interpretation of the test results are provided.

Stochastic modelling for the effects of micromixing on soot in turbulent non-premixed flames

The impact of micromixing and scalar dissipation rate (SDR) fluctuations on the evolution of soot particle size distribution (PSD) dynamics in non-premixed turbulent flames is investigated within the context of Large Eddy Simulation (LES). To accomplish this, a stochastic approach based on a physicochemical sectional soot model, spatially homogeneous Conditional Moment Closure (CMC) with first-order moment closure, and a stochastic differential equation for the SDR are employed, mimicking the function of an LES sub-grid scale (SGS) combustion model. After linking the magnitude of SDR fluctuations to the LES filter size, it was found that the standard deviation of observables, such as the soot volume fraction and soot number density, decreases rapidly with increasing LES filter size, which can significantly influence the intermittency of soot reproduced by models. Mean conditional expectations are also affected, indicating a closure problem, with the mean soot volume fraction, in particular, showing a decrease of up to 20% in the case considered compared to a direct numerical simulation resolution even when the Pope criterion is satisfied. The influence of SDR fluctuations on the dynamic behaviour of the soot PSD is further discussed under different working assumptions for particle transport, and the role of differential diffusion in soot oxidation- and formation-dominant regions is particularly highlighted. The findings underline the shortcomings of LES-CMC and similar mixture-fraction-based combustion models in capturing the dynamic evolution of soot at the SGS, which has significant implications for modelling the emissions of practical combustion devices. However, this study also offers a framework for better evaluating the effectiveness of these models using numerical experimentation and a stochastic model for the turbulent fluctuations of the micromixing rate.

Impact of Soot on Internal Combustion Engine Lubrication—Oil Condition Monitoring, Tribological Properties, and Surface Chemistry

In the study at hand, a systemic investigation regarding the tribochemical effects of crankcase soot is presented. Sooted oils were generated via an engine dynamometer test. Both conventional as well as advanced oil condition monitoring methods indicated a mild degradation of additives. The wear volume was greatly increased with the sooted oils in model tribometer tests, despite the high residual zinc dialkyl dithiophosphate (ZDDP) antiwear (AW) levels. Once the soot was removed via ultracentrifugation, the wear volume returned to levels comparable to the fresh oil. Surface investigations revealed that ZDDP tribofilms could not form in the sooted oils, as only a thin sulfide layer was present on the metal surfaces. Meanwhile, typical tribofilms were observable with centrifuged oils. The results indicated that a tribocorrosive mechanism is most likely responsible for the elevated wear in the sooted oils, where only the iron sulfide base layer of ZDDP films is formed, which is then rapidly removed by the soot particles in an abrasive manner.

Ecotoxicological assessment of waste scrubber water in unicellular algae (Tetraselmis suecica) and Blue Mussel (Mytilus edulis) larvae

Marine scrubbers can be classified into wet and dry scrubbers. Scrubber water (also known as washwater) from both wet scrubber systems has been found to release acidic water containing nutrients and contaminants back to the marine environment, including metals, aromatic hydrocarbons, and soot particles. This is especially true for the open-loop scrubbers that utilize the natural alkalinity of seawater and keep a high flow of process water in order to reduce SO2 in the exhaust and the washwater is discharged to sea, most often without substantial treatment. Little is known about potential impact of the discharged washwater on the marine environment. In ecotoxicological tests, a number of marine organisms have shown negative effects after acute and chronic exposures to varying concentrations of scrubber water, but the main pollutants involved in these responses are not clear yet. The aim of this study was to evaluate the effect of the main pollutants found in open-loop scrubber discharge water for survival, feeding and development of different species at the base of the food web after acute exposures to gas scrubber effluent. Toxicity, mortality, and physiology have been evaluated in marine microalgae, Tetraselmis suecica, and blue mussel (Mytilus edulis) larvae. Direct exposure to scrubber water appears to adversely affect biological and reproductive parameters in invertebrates, raising substantial concerns about ongoing open-loop exhaust gas scrubber system deployment.

Study on the Effect of Coal Grain Size on the Morphology of Soot Generated During Combustion

This study performed an experimental exploration to analyze the influence of different grain sizes of coal on the nanostructure and morphological parameters of soot generated during combustion. Initially, primary and mature soot samples were gained from the combustion flames of two different grain sizes of coal (less than 150 μm, named sample #1, and 6–8 mm, named sample #2) by using thermophoresis sampling technology. Subsequently, the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to investigate and analyze the soot samples, with the aim of obtaining their morphological parameters and nanostructure characteristics. The TEM images indicate that the nascent soot produced during the flame formed by small-sized coal is relatively uniform, with individual particles 8–14 nm in size. The grain size of the nascent soot produced by large-sized coal is much larger, within a wide range of 50–350 nm. Additionally, the nanostructures of the nascent soot particles produced by samples #1 and #2 mainly consist of upright parallel crystal stripes. The crystal stripes of the soot particles formed by sample #1 have obvious microcrystalline structures, whereas only a small amount of microcrystalline structure is found at the edge of sample #2. Compared with sample #2, the soot formed during the combustion of sample #1 exhibits a denser crystalline structure. The SEM results indicate that the mature soot agglomerates formed in sample #2 are larger and more in quantity compared to sample #1. Furthermore, the mature soot agglomerates formed in sample #2 have a stronger coagulation performance and a more compact structure than that formed in sample #1.

Enhanced NOx-assisted soot combustion by cobalt doping to weaken mullite Mn-O bonds for lattice oxygen activation

Catalytic combustion is widely regarded as the most efficient technique for removing soot particulates from diesel engine exhaust, with its efficiency largely dependent on the performance of catalysts. In this study, a series of YMn1−xCoxO5-ζ catalysts were synthesized using a hydrothermal method to investigate their catalytic properties in soot oxidation. Among these catalysts, YMCo-0.2 exhibited the highest catalytic activity, achieving 90 % soot conversion at 392 °C and demonstrating robust tolerance in the presence of water vapor and SO2. Structural characterization revealed that Co doping did not alter the fundamental crystal structure of YMn2O5 mullite. Through some characterization comprehensive analysis, and DFT calculations further supported the experimental findings, indicate that Co substitution significantly increased the lattice oxygen mobility and surface active oxygen content. Compared to the surface lattice oxygens at other positions, the weakening of the Mn-O bond results in the lattice oxygens in the Co-O-Mn4+ sites in the catalysts exhibiting higher reactivity. Additionally, the catalyst displayed strong NO and O2 adsorption and activation capabilities, indicating its potential for efficient NOx-assisted soot combustion. This study provides insights for designing and optimizing mullite catalysts for soot combustion.