Ultrafine Particles Research Articles

Titanium nitride@nitrogen-doped carbon nanocage composites as high-performance cathodes for aqueous Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) pertain to a new type of electrochemical energy storage device that has received considerable attention. They integrate the advantages of high-energy Zn-ion batteries and high-power supercapacitors to meet the demand for low-cost, long-term durability, and high safety. Nevertheless, the challenge caused by the finite ion adsorption/desorption capacity of carbon electrodes gravely limits their energy densities. This work describes titanium nitride@nitrogen-doped carbon nanocage (TiN@NCNC) composite cathodes for AZHSCs to achieve a greatly improved energy density, and the composites can be facilely synthesized based on the calcination of a mixture of tetrabutyl titanate and zeolitic imidazolate framework-8 in argon atmosphere. The resulting composites are featured by the ultra-fine TiN particles dispersed uniformly on the NCNC surfaces, enhancing the Zn2+ storage capabilities. Using TiN@NCNC cathodes, the AZHSCs can operate stably with a high energy density of 154 Wh kg−1 at a specific power of 270 W kg−1 and achieve a remarkable capacity retention of 88.9 % after 104 cycles at 5 A g−1. At an extreme specific power of 8.7 kW kg−1, the AZHSCs can retain an energy density of 97.2 Wh kg−1. With these results, we stress that the TiN@NCNC cathodes render high-performance AZHSCs and the facile one-pot method can easily be scaled up, which enables AZHSCs a new energy-storage component for managing intermitted renewable energy sources.

Air pollutant exposure concentrations from cooking a meal with a gas or induction cooktop and the effectiveness of two recirculating range hoods with filters

This study compares air pollutant concentrations resulting from cooking with gas or induction cooktops, with or without either of two recirculating range hoods with filters. A meal of pasta, plant-based “meat” sauce and stir-fried broccoli was cooked three times for each cooktop and hood combination in a 158 m3 room. Time-resolved measurements were made of nitrogen oxides (NOX), carbon dioxide (CO2), size-resolved particles, and speciated volatile organic compounds (VOCs) during cooking and 30 minutes after cooking. Cooking with induction used half as much energy, produced no discernible NOX, and significantly reduced ultrafine particles (UFP, diameter < 100 nm) and CO2 compared to gas cooktops. Induction produced statistically higher PM2.5 when calculated using size-resolved particle measurements from one pair of instruments, but the difference was not discernible when calculating from another pair. With gas cooktops, roughly half of the PM2.5 was in particles smaller than 0.3 μm and thus below the lower quantitation threshold for many optical particle instruments; optical devices may thus substantially under-report PM2.5 from gas cooking. VOCs did not significantly differ between gas and induction. Both recirculating range hoods substantially reduced all particle sizes when cooking with either fuel, and the reductions were larger for gas cooking. One of the range hoods also substantially lowered some of the VOCs.

A comprehensive study on the validation and application of multi-lognormal distribution models for atmospheric particles

The particle number size distribution (PNSD) is crucial for evaluating air quality and mitigating environmental pollution, as particles of different sizes have diverse effects on human health and climate. However, obtaining a comprehensive understanding of PNSD is challenging due to its inherent complexities and variability. Multi-lognormal distribution models are employed to fit PNSD, as seen in climate models, but discrepancies between model fits and observed PNSD persist. This study adopts hourly data from 2017 to 2020 across eight monitoring sites in diverse environments—rural, urban, mountainous, and polar, and compares the observed PNDS with those simulated by multi-lognormal distribution models. The results demonstrated that the model generally achieved a high correlation with observed PNSD data (r2 > 0.75), effectively capturing key characteristics of nucleation and Aitken mode particles. However, the model had a tendency to overestimate the total number concentration by approximately 1.09 times, particularly noticeable under conditions of high concentrations of smaller particles. The model successfully represented prevalent bimodal size distribution patterns in urban areas with high ultrafine particle concentrations, though its performance was slightly less accurate in scenarios involving trimodal distributions. Despite these strong correlations and the model's ability to reflect diurnal and seasonal variations, which suggests its broad applicability and utility, there were notable limitations on smaller time scales and in specific particle size ranges. These limitations were particularly evident in capturing detailed phenomena relevant to new particle formation events, indicating areas where model refinement is necessary. The results highlighted the importance of investigating discrepancies between model predictions and actual observations, which is crucial for refining climate models that utilize PNDS. The uniform comparison facilitated a detailed exploration of particle properties from model results, offering deeper insights into aerosol behavior and its environmental impacts.

Magnetic enhancement in paleosols with hydroclimatic and vegetation cover variabilities (Holocene vs. late MIS 3) in the central Korean Peninsula

Magnetic susceptibility enhancement (kE) is useful for reconstructing terrestrial paleohydroclimate variabilities. However, kE and its driving process(es) in the Korean Peninsula remain uninvestigated. Therefore, this study investigated two kEs of similar magnitudes, dated MIS 1 (Holocene) and late MIS 3 (~ 29–36 ka), from a paleosol sequence in the upland of paleo-fluvial terrace in the central Korean Peninsula. We observed increased ferri- and antiferro-magnetic mineral components,including ultrafine particles, and stronger chlorite weathering for the two kEs, suggesting pedogenic component predominance. The Fe-bearing (phyllo)silicate weathering mechanism proposed for the Chinese Loess Plateau sequences can explain the pedogenesis-induced kEs for the studied site. Superparamagnetic-domain (SPD) to pseudo-single-domain sized particles of pedogenic magnetite are likely major contributors to kEs. Moreover, we recognized the younger kE interval as more SPD contribution but less in total ferrimagnetic contribution, and more antiferromagnetic contribution than the older ones. The magnetic differences between the periods can result from vegetation cover impact and surrounding hydroclimate conditions, consistent with the recent suggestion for part of the southeast Chinese sites with relatively more rainfall. Consequently, our study provides a baseline for improving the relationship between mineral magnetic signals and local/regional hydroclimatic and environmental variabilities.

Biogenic Origin of Fe-Mn Crusts from Hydrothermal Fields of the Mid-Atlantic Ridge, Puy de Folles Volcano Region

Ferromanganese formations are widespread in the Earth’s aquatic environment. Of all the mechanisms of their formation, the biogenic one is the most debatable. Here, we studied the Fe-Mn crusts of hydrothermal fields near the underwater volcano Puy de Folles (rift valley of the Mid-Atlantic Ridge). The chemical and mineralogical composition (optical and electron microscopy with EDX, X-ray powder diffraction, X-ray fluorescence analysis, Raman and FTIR spectroscopy, gas chromatography—mass spectrometry (GC-MS)) and the magnetic properties (static and resonance methods, including at cryogenic temperatures) of the samples of Fe-Mn crusts were investigated. In the IR absorption spectra, based on hydrogen bond stretching vibrations, it was concluded that there were compounds with aliphatic (alkane) groups as well as compounds with double bonds (possibly with a benzene ring). The GC-MS analysis showed the presence of alkanes, alkenes, hopanes, and steranes. Magnetically, the material is highly coercive; the blocking temperatures are 3 and 13 K. The main carriers of magnetism are ultrafine particles and X-ray amorphous matter. The analysis of experimental data allows us to conclude that the studied ferromanganese crusts, namely in their ferruginous phase, were formed as a result of induced biomineralization with the participation of iron-oxidizing and iron-reducing bacteria.

Characterization of carbonaceous components and PAHs on ultrafine particles in Phnom Penh, Cambodia.

This study investigated seasonal fluctuations in particulate matter (PM) concentrations, including carbon and polycyclic aromatic hydrocarbon (PAH) components, in Phnom Penh, Cambodia, focusing on ultrafine particles (UFPs or ≤ 100nm). UFP levels were notably higher during the dry season, averaging 23.73 ± 3.7µg/m3 compared to 19.64 ± 3.4µg/m3 in the wet season, attributed to increased emissions from vehicles and agricultural burning. In contrast, lower concentrations during the wet season were due to scavenging effect of rain. When compared to other Southeast Asian cities, UFP levels in Phnom Penh were significantly higher during the dry season, surpassing those in cities like Bangkok and Kuala Lumpur. Seasonal variations in carbonaceous components showed higher elemental carbon (EC) and total carbon (TC) during the dry season, with EC/TC ratios suggesting substantial influence from vehicular emissions and biomass burning. PAH analysis revealed seasonal disparities, with higher concentrations of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF) during the wet season, whereas fluoranthene (Flu) and pyrene (Pyr) were consistently present, indicating diverse PAH sources. The Flu/(Flu + Pyr) ratios, indicative of biomass burning, were higher in the dry season. Correlations between PAHs and carbon components confirmed combustion as a significant source of PAHs, aligning with global trends. This emphasizes the need to address distinct PM sources during various season in Phnom Penh.

Comparative Analysis of Primary and Secondary Emission Mitigation Measures for Small-Scale Wood Chip Combustion

The objective of this study is to systematically investigate not only the influence of different additive types—beyond the much-considered case of aluminum-silicate-based additives—but also to carry out an additional comparison between primary and secondary emission mitigation measures during small-scale wood-chip combustion. Hence, combustion trials are realized within a 33-kW combustion plant. Pine wood chips additivated with 1.0 wt%a.r. of four additives have shown promising emission reduction effects in the past; namely kaolin (i.e., aluminum-silicate-based), anorthite (i.e., aluminum-silicate- and calcium-based), aluminum hydroxide (i.e., aluminum-based), and titanium dioxide (i.e., titanium-based). In addition to the primary mitigation measure (i.e., (fuel) additivation), an electrostatic precipitator (ESP) as a common secondary mitigation measure for total particulate matter (TPM) reduction is used for comparison. In addition to standard analyses (e.g., gravimetric determination of TPM emissions), an extended methodology (e.g., characterization of the elemental composition and ultrafine particle fraction of TPM emissions) is applied. The results show that the additivation of wood chips with kaolin and anorthite can lead to an operation of the combustion plant in compliance with the German legal TPM limit values by undercutting the absolute emission level achievable by the ESP. Additionally, kaolin and anorthite achieve significant reductions in carbon monoxide (CO) emissions, while kaolin simultaneously, and similarly to ESP, also leads to a shift in the particle size number distribution of PM emissions towards coarser particles. All additives show a significant reduction of potassium (K) emissions by the formation of high-temperature stable K compounds in the resulting ashes.

Chemically Resolved Respiratory Deposition of Ultrafine Particles Characterized by Number Concentration in the Urban Atmosphere.

Ultrafine particles (UFPs) dominate the atmospheric particles in number concentration, impacting human health and climate change. However, existing studies primarily rely on mass-based approaches, leading to a restricted understanding of the number-based and chemically resolved health effects of atmospheric UFPs. In this study, we utilized a high-mass-resolution single-particle aerosol mass spectrometer to investigate the online chemical composition and number size distribution of ultrafine, fine, and coarse particles during the summertime in urban Shenzhen, China. Human respiratory deposition dose assessments of particles with varying chemical compositions were further conducted by a respiratory deposition model. The results showed that during our observation, particles containing elemental carbon (EC) were the dominant components in UFPs (0.05-0.1 μm). Compared to fine and coarse particles, UFPs can deposit more deeply into the respiratory tract with a daily dose of ∼2.08 ± 0.67 billion particles. Among the deposited UFPs, EC-cluster particles constituted ∼85.7% in number fraction, accounting for a daily number dose of ∼1.78 billion particles, which poses a greater impact on human health. Simultaneously, we found discrepancies in the chemically resolved particle depositions among number-, surface area-, and mass-based approaches, emphasizing the importance of an appropriate metric for particle health-risk evaluation.

Exposure to ultrafine particles, black carbon and particulate matter during commute in a suburb from the Yangtze River Delta, China

This study evaluated the exposure of commuters to particulate matter (PM), black carbon (BC), and ultrafine particulate matter (UFP) concentrations in five different traffic microenvironments (bike, bus, taxi, electric motorbike, and subway) under various conditions, such as regular and dust days, weekdays and weekends, and peak and off-peak commute hours in Nanjing, China. In the morning peak hours, bicycle commuters were exposed to the highest PM concentration, those on buses to the highest BC concentration (3.4 ± 3.0 μg/m3), and those on buses and taxis to the highest UFP number concentration. Throughout the rides, the commuter on the subway had the lowest mean exposure concentration of PM, BC, and UFP number. Bicycle commuters (16.25 μg/km) had the highest total inhaled dose of PM2.5, followed by e-bikers (1.98 μg/km), bus riders (1.28 μg/km), taxi riders (0.69 μg/km), and subway users (0.45 μg/km). Weekday PM2.5 exposure levels (115 μg/m3) and BC exposure levels (1.8 μg/m3) were higher than weekend levels (170% and 158%, respectively). The mean exposure concentration of PM10 (1299 ± 1286 μg/m3) in the evening peak of dust days was 803% and 994% higher than the mean concentrations on weekdays and holidays, respectively. PM2.5, PM10, and BC concentrations on dust days were significantly higher than those on weekdays and holidays. The overall mean ratios of PM1/PM2.5 and PM2.5/PM10 were 0.47 and 0.36, respectively, and the five commuting microenvironments had higher proportions of 2.5–10 μm and 1–2.5 μm particles in PM10 and PM2.5, respectively. Reducing the sources of particulate matter in the corresponding particle size ranges could lower exposure levels.

Comparative experimental study on the co-firing characteristics of water electrolysis gas (HHO) and lean coal/lignite with different injection modes in a one-dimensional furnace

Zero-carbon fuels (H2/NH3) replacing coal co-firing is a promising way to address carbon emissions. Hydrogen co-firing helps improve combustion stability at low loads and control pollutant emissions. This study used a safer water electrolysis gas (HHO) for the multi-coal co-firing adaptability test. The effects of HHO injection mode and flow rate on combustion intensity, flue gas emissions, and fly ash characteristics were investigated. The results showed that HHO and lean coal/lignite co-firing could significantly increase the combustion temperature. The maximum temperature increases after co-firing were 108 °C and 95 °C. As the HHO increased, the CO2 in lignite co-firing increased, and CO and unburnt carbon decreased, while the opposite results were observed for lean coal (LC). At the 2200L/h HHO co-firing, CO2 decreases by 14.46 % and 27.22 % for LC premixed co-firing (PC) and staged co-firing (SC). Compared to SC, PC is more conducive to promoting the complete combustion of coke. The NOX emissions of HHO/LC co-firing are lower than those of pure coal, reaching the lowest value of ∼ 9 ppm under SC. As the HHO increases, the NOX of Lignite-PC first increases and then slowly decreases, while Lignite-SC has the opposite effect. Although various NOX emission trends are observed under different conditions, the results are dominated by a common mechanism − the competition between NOX reduction caused by HHO gas and the increase in co-firing temperature on NOX generation. The NOX of SC is all lower than that of PC. The SO2 emission from the LC co-firing decreases with the increase of HHO, while the SO2 from lignite increases. The SO2 of LC-SC can be reduced from ∼ 142 ppm to 0 ppm. HHO gas injection inhibits the release and oxidation of sulfur in lean coal. The differences in coal types lead to different changes in SO2 of co-firing. HHO gas reduced the SO3 content of lignite fly ash by 38.01 %. The high-temperature reduction atmosphere promotes the decomposition of sulfates and increases SO2 emissions. HHO co-firing refines the particle size of fly ash. The ultra-fine and micron particle matter (PM) increases, and the content of PM>100μm in Lignite-SC decreased by 10.32 %.

Correction: Toxicity of ultrafine particles during Diwali’s firework: an in-vitro study of A549 cells

Correction: Toxicity of ultrafine particles during Diwali’s firework: an in-vitro study of A549 cells

Investigation into personal exposure to ultrafine particle (UFP) in Phnom Penh, Cambodia: A pilot study

This pilot study aimed to examine personal exposure to ultrafine particles (UFP or particle smaller than 100 nm) in Phnom Penh, Cambodia through the assessment of different transportation modes, travel routes, and the comparison of indoor and outdoor activities. A handheld UFP counter was used to record the UFP size, concentration and as well as Lung Deposited Surface Area (LDSA). GPS data was recorded using a GPS watch and then combined with the UFP data before further analysis with geospatial software (QGIS) along with OpenStreetMap to generate spatial data of personal exposure to UFP. The study revealed significant differences in UFP exposure between motorbike and bus users, with average UFP concentrations of approximately 114,300 and 171,700 particles/cm³ for motorbike users, and 22,600 and 37,200 particles/cm³ for bus users on lines 3 and 4A, respectively. These concentrations exceed WHO guidelines, which consider UFP levels above 20,000 particles/cm³ per hour as high and potentially harmful. The results of our study also revealed varying amounts of exposure on different roadways, with Russian Federation Blvd consistently exhibited the highest concentrations of UFP, especially during periods of peak traffic. Furthermore, indoor environments generally presented lower UFP exposure. Specific activities or events were found to generate temporary increases in particle concentration. It was shown that weekdays had elevated levels of UFP compared to weekends. Regardless of the limitations of the study, especially its small sample size, it provides significant initial observations, highlighting the urgent need for mitigation strategies and further comprehensive studies in the region.

Commuter exposure to ultrafine particles (UFPs), lung deposited surface area (LDSA), and noise in Ho Chi Minh City, Vietnam

IntroductionTransport is a main contributor to air and noise pollution, particularly in urban areas with the high number of motorized vehicles. Promoting active transport (i.e., cycling and walking) and public transport is an instrumental factor in reducing traffic-related air and noise pollution. However, commuters of these transport modes are often exposed to high air and noise pollution than other commuter groups. MethodsThe levels of exposure to UFP, LDSA, and noise during commuting of different transport modes in Ho Chi Minh City (HCMC) were measured and compared. Then, the dose of inhaled pollutants during commuting was calculated for each commuter group by considering the travel time and minute ventilation. ResultsThe level of exposure to air and noise pollution varies across transport modes. Cyclists and motorcyclists were exposed to the highest level of air and noise pollution. Motorcyclists and cyclists were exposed to the highest UFP number concentrations during their trips, 3.6*105 and 3.1*105 particles/cm3, respectively. Car commuters were exposed to the lowest air and noise pollution level, followed by bus commuters. When considering the minute ventilation and travel time, cyclists inhaled significantly higher levels of air pollution than other commuters, followed by pedestrians, motorcyclists, bus commuters, and car users. As a result, the health impacts of exposure to traffic-related air and noise pollution for active commuters could be greater than other commuter groups. ConclusionsPromoting active and public transport is a promising approach to improving air quality and reducing congestion in HCMC. Using these transport modes also has potential positive health effects on commuters through physical activities. However, active commuters are faced with the highest risk of exposure to high air and noise pollution levels. To promote active transport and public transport in HCMC, measures to reduce the level of exposure to air and noise pollution for these commuter groups are needed.

LP-55 Characterization and quantification of fine and ultrafine particles from ilmenite smelting process

LP-55 Characterization and quantification of fine and ultrafine particles from ilmenite smelting process

Explosive growth characteristics of 5.6–560 nm particles and deposition in human respiratory during spring in Yangtze River Delta region, China

Studying the contribution of regional transport to ultrafine particles (UFPs) and the deposition effect of nanoscale particles in human respiratory system is conducive to exploring the impact of atmospheric particles on the environment and human health. Based on the data set of number concentration spectrum in the particle size range of 5.6–560 nm in the spring of Hefei, the Yangtze River Delta region obtained by a fast mobility particle sizer, the explosive growth characteristics, potential source identification and deposition flux analysis of UFPs were systematically studied. The results showed that the frequency of new particle formation (NPF) events during spring was 31.5 %. SO2 and O3 contribute to NPF events. Daytime, higher temperature, stronger solar radiation and lower humidity were more conducive to the explosive growth of UFPs. In addition, regional transport of pollutants from the cities around Hefei played an important role in the accumulation mode particles, which were mainly affected by the land-source air mass from northwest Jiangsu (23.64 %) and the sea-source air mass from the Yellow Sea (23.99 %). It was worth noting that approximately 10,406 ng of UFPs enters the human respiratory system every day. The main deposition area of 5.6–560 nm nanoscale particles was alveolar, 5.6–400 nm is more likely to be deposited on alveolar, while nanoscale particles with particle size between 400 and 560 nm is more likely to be deposited on head airways. This study identified the deposition risk of nanoscale particles in the respiratory system under different particle sizes.

P21-19 The secondary organ translocation of inhaled ultrafine particulate matter in mice

P21-19 The secondary organ translocation of inhaled ultrafine particulate matter in mice

Preparation and Molecular Dynamic Simulation of Superfine CL-20/TNT Cocrystal Based on the Opposite Spray Method.

In view of the current problems of slow crystallization rate, varying grain sizes, complex process conditions, and low safety in the preparation of CL-20/TNT cocrystal explosives in the laboratory, an opposite spray crystallization method is provided to quickly prepare ultrafine explosive cocrystal particles. CL-20/TNT cocrystal explosive was prepared using this method, and the obtained cocrystal samples were characterized by electron microscopy morphology, differential thermal analysis, infrared spectroscopy, and X-ray diffraction analysis. The effects of spray temperature, feed ratio, and preparation method on the formation of explosive cocrystal were studied, and the process conditions of the pneumatic atomization spray crystallization method were optimized. The crystal plane binding energy and molecular interaction forces between CL-20 and TNT were obtained through molecular dynamic simulation, and the optimal binding crystal plane and cocrystal mechanism were analyzed. The theoretical calculation temperature of the binding energy was preliminarily explored in relation to the preparation process temperature of cocrystal explosives. The mechanical sensitivity of ultrafine CL-20/TNT cocrystal samples was tested. The results showed that choosing acetone as the cosolvent, a spraying temperature of 30 °C, and a feeding ratio of 1:1 was beneficial for the formation and growth of cocrystal. The prepared CL-20/TNT cocrystal has a particle size of approximately 10 μm. The grain size is small, and the crystallization rate is fast. The impact and friction sensitivity of ultrafine CL-20/TNT cocrystal samples were significantly reduced. The experimental process conditions are simple and easy to control, and the safety of the preparation process is high, providing certain technical support for the preparation of high-quality cocrystal explosives.

Indoor Emission, Oxidation, and New Particle Formation of Personal Care Product Related Volatile Organic Compounds.

Personal care products (PCPs) contain diverse volatile organic compounds (VOCs) and routine use of PCPs indoors has important implications for indoor air quality and human chemical exposures. This chamber study deployed aerosol instrumentation and two online mass spectrometers to quantify VOC emissions from the indoor use of five fragranced PCPs and examined the formation of gas-phase oxidation products and particles upon ozone-initiated oxidation of reactive VOCs. The tested PCPs include a perfume, a roll-on deodorant, a body spray, a hair spray, and a hand lotion. Indoor use of these PCPs emitted over 200 VOCs and resulted in indoor VOC mixing ratios of several parts per million. The VOC emission factors for the PCPs varied from 2 to 964 mg g-1. We identified strong emissions of terpenes and their derivatives, which are likely used as fragrant additives in the PCPs. When using the PCPs in the presence of indoor ozone, these reactive VOCs underwent oxidation reactions to form a variety of gas-phase oxidized vapors and led to rapid new particle formation (NPF) events with particle growth rates up to ten times higher than outdoor atmospheric NPF events. The resulting ultrafine particle concentrations reach ∼34000 to ∼200000 cm-3 during the NPF events.

Dynamic evolution of particulate and gaseous emissions for typical residential coal combustion

Residential coal combustion still accounts for half of the heating energy consumption in many developing countries. The dynamic variation during the combustion process importantly determines the combustion facility design and appropriate air quality assessment, which was omitted in conventional studies. This study investigated the emissions of particulate and gaseous pollutants during the combustion process for typical coal types using online monitoring. During the first pyrolysis stage with temperature climbing, the organic aerosols (OA) and gases reached peak concentration. The second fierce combustion stage had the highest temperature and produced the highest cumulative emissions, particularly a substantial amount of black carbon for coals with higher volatile content. Using higher-quality coals will undoubtedly reduce PM emissions, by a factor of 10 from bituminous to anthracite coal. However, more ultrafine particles (d < 0.1 μm) from cleaner coal may pose additional health risks. Anthracite and honeycomb coal had approximately twice the energy content and emitted more CO2 per unit mass of fuel and had more persistent SO2 emissions throughout the burnout stage. The oxygenation of OA and organic gases remained increased during combustion, suggesting the pyrolysis products underwent oxidation before being emitted. The investigation of the coal combustion process suggests the importance of reducing volatiles to control PM emissions, but the potential negative synergistic effects between PM reduction and increased carbon emissions should also be considered.

Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID-19 lockdowns

Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID-19 lockdowns