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Materials (Basel, Switzerland) Jan 2024Measuring the size distribution and temperature of high-temperature dispersed particles, particularly in-flame soot, holds paramount importance across various...
Measuring the size distribution and temperature of high-temperature dispersed particles, particularly in-flame soot, holds paramount importance across various industries. Laser-induced incandescence (LII) stands out as a potent non-contact diagnostic technology for in-flame soot, although its effectiveness is hindered by uncertainties associated with pre-determined thermal properties. To tackle this challenge, our study proposes a multi-parameter inversion strategy-simultaneous inversion of particle size distribution, thermal accommodation coefficient, and initial temperature of in-flame soot aggregates using time-resolved LII signals. Analyzing the responses of different heat transfer sub-models to temperature rise demonstrates the necessity of incorporating sublimation and thermionic emission for accurately reproducing LII signals of high-temperature dispersed particles. Consequently, we selected a particular LII model for the multi-parameter inversion strategy. Our research reveals that LII-based particle sizing is sensitive to biases in the initial temperature of particles (equivalent to the flame temperature), underscoring the need for the proposed multi-parameter inversion strategy. Numerical results obtained at two typical flame temperatures, 1100 K and 1700 K, illustrate that selecting an appropriate laser fluence enables the simultaneous inversion of particle size distribution, thermal accommodation coefficient, and initial particle temperatures of soot aggregates with high accuracy and confidence using the LII technique.
PubMed: 38591434
DOI: 10.3390/ma17030634 -
Chemosphere May 2024Dissolved black carbon (DBC) is the ubiquitous component of dissolved organic matter pools with the high reactivity for disinfection byproducts formation. However, it is...
Dissolved black carbon (DBC) is the ubiquitous component of dissolved organic matter pools with the high reactivity for disinfection byproducts formation. However, it is unknown that the influence of molecular weight (MW) of natural organic matter (NOM) on the DBC removal from potable water sources. Therefore, it was studied that the DBC removal by coagulation in the presence of the NOM with various molecular weights. The DBC removal was promoted due to the presence of NOM and the promotion degree decreased with decreasing MW of NOM. Furthermore, the removal ratio of humic-like component increased as the MW of NOM decreased, suggesting that the competition between DBC and NOM increased with decreasing MW. The functional groups after coagulation were the same with that before coagulation as the MW of NOM varied, suggesting that the molecular structure was not the key factor of influencing the DBC removal. This study will give the deep insight into the prediction of the DBC removal ratio by coagulation based on the MW of NOM in water sources.
Topics: Molecular Weight; Water Purification; Humic Substances; Carbon; Water Pollutants, Chemical; Soot; Drinking Water; Disinfection; Organic Chemicals
PubMed: 38588894
DOI: 10.1016/j.chemosphere.2024.141940 -
Environmental Science & Technology Apr 2024The characteristics of aviation-induced aerosol, its processing, and effects on cirrus clouds and climate are still associated with large uncertainties. Properties of...
The characteristics of aviation-induced aerosol, its processing, and effects on cirrus clouds and climate are still associated with large uncertainties. Properties of aviation-induced aerosol, however, are crucially needed for the assessment of aviation's climate impacts today and in the future. We identified more than 1100 aircraft plume encounters during passenger aircraft flights of the IAGOS-CARIBIC Flying Laboratory from July 2018 to March 2020. The aerosol properties inside aircraft plumes were similar, independent of the altitude (i.e., upper troposphere, tropopause region, and lowermost stratosphere). The exhaust aerosol was found to be mostly externally mixed compared to the internally mixed background aerosol, even at a plume age of 1 to 3 h. No enhancement of accumulation mode particles (diameter >250 nm) could be detected inside the aircraft plumes. Particle number emission indices (EIs) deduced from the observations in aged plumes are in the same range as values reported from engine certifications. This finding, together with the observed external mixing state inside the plumes, indicates that the aviation exhaust aerosol almost remains in its emission state during plume expansion. It also reveals that the particle number EIs used in global models are within the range of the EIs measured in aged plumes.
PubMed: 38588448
DOI: 10.1021/acs.est.3c09728 -
The Science of the Total Environment Jun 2024Atmospheric aerosol types and characteristics have regional and seasonal characteristics mainly due spatial and temporal differences in emission sources and diffuse...
Atmospheric aerosol types and characteristics have regional and seasonal characteristics mainly due spatial and temporal differences in emission sources and diffuse transport conditions. We explored regional three-dimensional spatial and temporal distribution characteristics of aerosol types in Central Asia from daytime to nighttime by using long-term (2007-2021) CALIPSO lidar measurements. The three results are as follows: (1) Average aerosol optical depth (AOD) values during the 14 years were 0.44 and 0.47 during daytime and nighttime, respectively, with an overall decreasing trend, among which the AOD in spring in the southern border region and in winter in the northern border region showed high values, 0.66 and 0.31 during daytime and 0.69 and 0.33 during nighttime, respectively, and nighttime AOD values were higher than those of daytime, possibly due to the lower signal-to-noise ratio of the CALIPSO during the daytime than during the nighttime. (2) The primary representative aerosol type in the Taklamakan Desert region being pure sand and dust, and more apparent winter-polluted sand and dust exist along the northern slope of the Tianshan Mountains in Xinjiang in winter than in other areas. High-altitude soot mainly existed below 4 km and was primarily concentrated in northern Central Asia, with the highest values (0.016 and 0.003) in summer and winter, respectively, which may be due to different diffusion and transport conditions. (3) Dust aerosols in spring were mainly concentrated in the region of 2-6 km in the Taklamakan Desert area; pure dust particles in summer and fall lifted height diffusion and gradually moved to the northern border region; polluted dust was mainly in northern Xinjiang in fall and winter and spread to northern Central Asia; and the average top height of aerosols in the transmission process reached the top of the troposphere, and transmission height was higher than source area.
PubMed: 38580123
DOI: 10.1016/j.scitotenv.2024.172196 -
Environmental Research Jul 2024The escalating issue of air pollution has become a significant concern in urban regions, including Islamabad, Pakistan, due to the rise in air pollutant emissions driven...
The escalating issue of air pollution has become a significant concern in urban regions, including Islamabad, Pakistan, due to the rise in air pollutant emissions driven by economic and industrial expansion. To gain a deeper understanding of air pollution, a study was conducted during winter 2022-2023, assessing physical, chemical, and biological factors in Islamabad. The findings revealed that the average concentration of fine particulate matter (PM2.5) was notably greater than the World Health Organization (WHO) guidelines, reaching 133.39 μg/m³. Additionally, the average concentration of bacteria (308.64 CFU/m³) was notably greater than that of fungi (203.55 CFU/m³) throughout the study. Analytical analyses, including SEM-EDS and FTIR, showed that the PM2.5 in Islamabad is composed of various particles such as soot aggregates, coal fly ash, minerals, bio-particles, and some unidentified particles. EF analysis distinguished PM2.5 sources, enhancing understanding of pollutants origin, whereas Spearman's correlation analysis elucidated constituent interactions, further explaining air quality impact. The results from the Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) indicated a gradual increase in the total elemental composition of PM2.5 from autumn to winter, maintaining high levels throughout the winter season. Furthermore, a significant variation was found in the mass concentration of PM2.5 when comparing samples collected in the morning and evening. The study also identified the presence of semi-volatile organic compounds (SVOCs) in PM2.5 samples, including polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds, with notable variations in their concentrations. Utilizing health risk assessment models developed by the US EPA, we estimated the potential health risks associated with PM2.5 exposure, highlighting the urgency of addressing air quality issues. These findings provide valuable insights into the sources and composition of PM2.5 in Islamabad, contributing to a comprehensive understanding of air quality and its potential environmental and health implications.
Topics: Particulate Matter; Pakistan; Air Pollutants; Humans; Environmental Monitoring; Cities; Particle Size; Air Pollution
PubMed: 38574984
DOI: 10.1016/j.envres.2024.118862 -
Langmuir : the ACS Journal of Surfaces... Apr 2024The introduction of macroporous structures into three-way catalysts (TWCs) through polymer template-assisted spray drying has attracted attention because of its enhanced...
The introduction of macroporous structures into three-way catalysts (TWCs) through polymer template-assisted spray drying has attracted attention because of its enhanced gas diffusion and catalytic performance. However, the surface charge effect of polymeric template components has not been investigated to control the structure of the TWC particles during synthesis. Thus, this study investigated the effect of template surface charges on the self-assembly behavior of TWC nanoparticles (NPs) during drying. The self-assembly of TWC NPs and polymer particles with different charges produced a hollow structure, whereas using the same charges generated a porous one. Consequently, the mechanism of particle self-assembly during drying and final structure particle formation is proposed in this study. Here, porous TWC particles demonstrated a faster oxidation of soot particles than that of hollow-structured particles. This occurred as a result of the larger contact area between the catalyst surface and the solid reactant. Our findings propose a fundamental self-assembly mechanism for the formation of different TWC structures, thereby enhancing soot oxidation performance using macroporous structures.
PubMed: 38574288
DOI: 10.1021/acs.langmuir.4c00490 -
The Journal of Physical Chemistry. A May 2024This work studies the real gas effects on the autoignition of hydrocarbon fuels under high pressures, using normal dodecane (-dodecane) as the representative fuel and...
This work studies the real gas effects on the autoignition of hydrocarbon fuels under high pressures, using normal dodecane (-dodecane) as the representative fuel and the Redlich-Kwong equation of state (EoS) as the real gas description. It is demonstrated that the real gas description yields a shorter ignition delay time (IDT) compared with the ideal gas description, especially in low-temperature regimes which could encompass the negative temperature coefficient (NTC) phenomena and has a stronger dependence on the molecular volume than the attractive potential. The study further shows that high pressure facilitates low-temperature reaction pathways, where the compressibility factors of key reactants contribute to real gas effects. Moreover, the results suggest that accounting for real gas behavior leads to an increase in the formation of polycyclic aromatic hydrocarbons (PAHs), which, in turn, promotes soot generation.
PubMed: 38573007
DOI: 10.1021/acs.jpca.3c08395 -
Inorganic Chemistry Apr 2024The impact of variable valence A-sites on the redox property and reactivity of LnCeO compounds in soot particulate combustion has been investigated. It was observed that...
The impact of variable valence A-sites on the redox property and reactivity of LnCeO compounds in soot particulate combustion has been investigated. It was observed that YbCeO, YCeO, and GdCeO formed a rare earth C-type phase, while TbCeO formed a solid solution phase. Both TbCeO and YbCeO possess dual valence state A-sites, resulting in significantly more surface vacancies. Additionally, the advantageous solid solution phase structure of TbCeO leads to even more surface vacancies than YbCeO, which is crucial to generate active oxygen sites. Moreover, the introduction of NO into the reaction feed enhances combustion activity by producing active surface monodentate nitrates. A catalyst with higher numbers of surface vacancies exhibits improved NO oxidation ability and better NO utilization efficiency. Consequently, the TbCeO compound demonstrates not only the best soot combustion activity, but also an optimal NO-assistance effect. Therefore, it is concluded that variable valence A-site is the intrinsic factor to improve the reactivity of LnCeO catalysts.
PubMed: 38566011
DOI: 10.1021/acs.inorgchem.4c00142 -
Environmental Monitoring and Assessment Apr 2024Small mammals have a short lifetime and are strictly associated with their environment. This work aimed to use histopathology to assess the health of Holochilus...
Small mammals have a short lifetime and are strictly associated with their environment. This work aimed to use histopathology to assess the health of Holochilus chacarius in a rice agroecosystem in the Pantanal of Mato Grosso do Sul. During necropsy, fragments of the lung, kidney, skin, liver, and reproductive system of 33 animals were collected and submitted to histological processing. Tissue damages were evaluated as mild, moderate, and severe and arranged in a matrix for further statistical analysis. Furthermore, we used generalized linear models to verify the influence of tissue changes on the body condition, obtained by a regression between body mass and length. In the lungs, we found an intense inflammatory infiltrate associated with anthracosis that had a negative influence on the body's condition. Also, we observed degenerative and inflammatory changes in the liver, kidneys, skin, and reproductive system that ranged from mild to moderate. The histopathological lesions observed in this study may be associated with environmental alterations of anthropic origin such as the exposure to soot from wildfires and heavy metals, evidenced by lesions in the lung, kidney, and liver. The present study provided a histopathological matrix as a new approach that allows to classify and quantify the tissue alterations. Tissue changes when associated with body condition demonstrated to be an effective tool to assess the health of small free-living mammals, showing that these animals can be used as bioindicators of environmental condition.
Topics: Animals; Rodentia; Arvicolinae; Oryza; Wetlands; Environmental Monitoring; Sigmodontinae
PubMed: 38561512
DOI: 10.1007/s10661-024-12566-6 -
Scientific Reports Apr 2024The implications of adding cerium oxide (CeO) nanoparticles as a fuel additive to a castor oil biodiesel-diesel fuel blend on engine performance and emissions in a...
The implications of adding cerium oxide (CeO) nanoparticles as a fuel additive to a castor oil biodiesel-diesel fuel blend on engine performance and emissions in a single-cylinder four-stroke diesel engine under various speed were examined in the current study. The test fuels used were fossil diesel fuels, B5 blend biodiesel (as 5% biodiesel and 95% diesel), B10 blend biodiesel (as 10% biodiesel and 90% diesel), B15 blend biodiesel (as 15% biodiesel and 85% diesel), B20 blend biodiesel (as 20% biodiesel and 80% diesel), and B25 blend biodiesel (as 25% biodiesel and 75% diesel), with cerium oxide (CeO) nanoparticle additive (75 ppm). The result of the physio-chemical properties of the oil samples was within the limit of the ASTM standard. The addition of CeO nano additive to the biodiesel-diesel blends has demonstrated a significant reduction in emission and increased in engine performance for all biodiesel-diesel blends for the engine operating speed range. From the result B25 have the maximum reduction rate in BSFC and B10 have the minimum reduction rate in BSFC. The average maximum increment of thermal efficiency was 22.2% for B10 with CeO inclusion. CO emission increased as engine speed increased. HC emission was reduced for all blend, with and without CeO nano additions as speed increased. Maximum NO emission was seen at the rated speed of 2700 rpm without nano additive and at 2900 rpm with nano additive. CeO nano additive reduced the soot opacity by 11.56% for all biodiesel-diesel blends for the engine operating speed range. As the objective of this study the results indicates CeO nano additive reduced emissions and improved the performance. So, using sustainable biodiesel-diesel blends made from castor oil with CeO nano additive advisable in ideal operating conditions for diesel engines.
PubMed: 38561406
DOI: 10.1038/s41598-024-58420-0