Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 68
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Sci Technol ; 58(23): 10175-10184, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38771930

RESUMO

The interplay between sulfur and iron holds significant importance in their atmospheric cycle, yet a complete understanding of their coupling mechanism remains elusive. This investigation delves comprehensively into the evolution of reactive oxygen species (ROS) during the interfacial reactions involving sulfur dioxide (SO2) and iron oxides under varying relative humidity conditions. Notably, the direct activation of water by iron oxide was observed to generate a surface hydroxyl radical (•OH). In comparison, the aging of SO2 was found to markedly augment the production of •OH radicals on the surface of α-Fe2O3 under humid conditions. This augmentation was ascribed to the generation of superoxide radicals (•O2-) stemming from the activation of O2 through the Fe(II)/Fe(III) cycle and its combination with the H+ ion to produce hydrogen peroxide (H2O2) on the acidic surface. Moreover, the identification of moderate relative humidity as a pivotal factor in sustaining the surface acidity of iron oxide during SO2 aging underscores its crucial role in the coupling of iron dissolution, ROS production, and SO2 oxidation. Consequently, the interfacial reactions between SO2 and iron oxides under humid conditions are elucidated as atmospheric processes that enhance oxidation capacity rather than deplete ROS. These revelations offer novel insights into the mechanisms underlying •OH radical generation and oxidative potential within atmospheric interfacial chemistry.


Assuntos
Espécies Reativas de Oxigênio , Dióxido de Enxofre , Dióxido de Enxofre/química , Compostos Férricos/química , Radical Hidroxila/química , Oxirredução , Peróxido de Hidrogênio/química , Umidade
2.
Environ Sci Technol ; 58(13): 5911-5920, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38437592

RESUMO

HONO acts as a major OH source, playing a vital role in secondary pollutant formation to deteriorate regional air quality. Strong unknown sources of daytime HONO have been widely reported, which significantly limit our understanding of radical cycling and atmospheric oxidation capacity. Here, we identify a potential daytime HONO and OH source originating from photoexcited phenyl organic nitrates formed during the photoreaction of aromatics and NOx. Significant HONO (1.56-4.52 ppb) and OH production is observed during the photoreaction of different kinds of aromatics with NOx (18.1-242.3 ppb). We propose an additional mechanism involving photoexcited phenyl organic nitrates (RONO2) reacting with water vapor to account for the higher levels of measured HONO and OH than the model prediction. The proposed HONO formation mechanism was evidenced directly by photolysis experiments using typical RONO2 under UV irradiation conditions, during which HONO formation was enhanced by relative humidity. The 0-D box model incorporated in this mechanism accurately reproduced the evolution of HONO and aromatic. The proposed mechanism contributes 5.9-36.6% of HONO formation as the NOx concentration increased in the photoreaction of aromatics and NOx. Our study implies that photoexcited phenyl organic nitrates are an important source of atmospheric HONO and OH that contributes significantly to atmospheric oxidation capacity.


Assuntos
Poluentes Ambientais , Ácido Nitroso , Ácido Nitroso/análise , Radical Hidroxila , Oxirredução , Raios Ultravioleta , Nitratos
3.
Environ Sci Technol ; 58(14): 6071-6076, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38551192

RESUMO

The atmospheric oxidizing capacity is the most important driving force for the chemical transformation of pollutants in the atmosphere. Traditionally, the atmospheric oxidizing capacity mainly depends on the concentration of O3 and other gaseous oxidants. However, the atmospheric oxidizing capacity based on gas-phase oxidation cannot accurately describe the explosive growth of secondary particulate matter under complex air pollution. From the chemical perspective, the atmospheric oxidizing capacity mainly comes from the activation of O2, which can be achieved in both gas-phase and interfacial processes. In the heterogeneous or multiphase formation pathways of secondary particulate matter, the enhancement of oxidizing capacity ascribed to the O2/H2O-involved interfacial oxidation and hydrolysis processes is an unrecognized source of atmospheric oxidizing capacity. Revealing the enhanced oxidizing capacity due to interfacial processes in high-concentration particulate matter environments and its contribution to the formation of secondary pollution are critical in understanding haze chemistry. The accurate evaluation of atmospheric oxidizing capacity ascribed to interfacial processes is also an important scientific basis for the implementation of PM2.5 and O3 collaborative control in China and around the world.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Aerossóis/análise , Material Particulado/análise , Poluição do Ar/análise , China , Estações do Ano , Gases
4.
Anal Chem ; 96(10): 4048-4056, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38373182

RESUMO

In this work, we developed an alternative calibration method for measuring N2O5 with an iodide adduct mass spectrometer (I-CIMS). In this calibration method, N2O5 is heated and then quantified based on the decrease in the amount of NO due to its reaction with the pyrolysis product (NO3). This alternative calibration method was compared with the commonly used method utilizing NOx analyzers equipped with a photolytic converter, which gauge NO2 reduction as a result of its reaction with O3 to quantify N2O5. It is notable that the two methodologies demonstrate favorable consistency in terms of calibrating N2O5, with a variance of less than 10 %. The alternative calibration method is a more reliable way to quantify N2O5 with CIMS, considering the instability of the NO2 conversion efficiency of photolytic converters in NOx analyzers and the loss of N2O5 in the sampling line. The effects of O3 and relative humidity (RH) on the sensitivity toward N2O5 were further examined. There was minimal perturbation of N2O5 quantification upon exposure to O3 even at high concentrations. The N2O5 sensitivity exhibited a nonlinear dependence on RH as it initially rose and then fell. Besides I(N2O5)-, the collisional interaction between I(H2O)- and N2O5 also forms I(HNO3)-, which may interfere with the accurate quantification of HNO3. As a consequence of the pronounced dependence on humidity, it is advisable to implement humidity correction procedures when conducting measurements of N2O5.

5.
Sci Total Environ ; 921: 171100, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38387565

RESUMO

Indoor air quality is of major concern for human health and well-being. Nitrous acid (HONO) is an emerging indoor pollutant, and its indoor mixing ratios are usually higher than outdoor levels, ranging from a few to tens of parts per billion (ppb). HONO exhibits adverse effects to human health due to its respiratory toxicity and mutagenicity. Additionally, HONO can easily undergo photodissociation by ultraviolet light to produce hydroxyl radicals (OH•), which in turn trigger a series of further photochemical oxidation reactions of primary or secondary pollutants. The accumulation of indoor HONO can be attributed to both direct emissions from combustion sources, such as cooking, and secondary formation resulting from enhanced heterogeneous reactions of NOx on indoor surfaces. During the day, the primary sink of indoor HONO is photolysis to OH• and NO. Moreover, adsorption and/or reaction on indoor surfaces, and diffusion to the outside atmosphere contribute to HONO loss both during the day and at night. The level of indoor HONO is also affected by human occupancy, which can influence household factors such as temperature, humidity, light irradiation, and indoor surfaces. This comprehensive review article summarized the research progress on indoor HONO pollution based on indoor air measurements, laboratory studies, and model simulations. The environmental and health effects were highlighted, measurement techniques were summarized, pollution levels, sources and sinks, and household influencing factors were discussed, and the prospects in the future were proposed.

6.
J Am Chem Soc ; 146(2): 1467-1475, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38186050

RESUMO

We present a novel mechanism for the formation of photocatalytic oxidants in deliquescent NaCl particles, which can greatly promote the multiphase photo-oxidation of SO2 to produce sulfate. The photoexcitation of the [Cl--H3O+-O2] complex leads to the generation of Cl and OH radicals, which is the key reason for enhancing aqueous-phase oxidation and accelerating SO2 oxidation. The mass normalization rate of sulfate production from the multiphase photoreaction of SO2 on NaCl droplets could be estimated to be 0.80 × 10-4 µg·h-1 at 72% RH and 1.33 × 10-4 µg·h-1 at 81% RH, which is equivalent to the known O3 liquid-phase oxidation mechanism. Our findings highlight the significance of multiphase photo-oxidation of SO2 on NaCl particles as a non-negligible source of sulfate in coastal areas. Furthermore, this study underscores the importance of Cl- photochemistry in the atmosphere.

7.
Environ Sci Technol ; 57(37): 13937-13947, 2023 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-37691473

RESUMO

Secondary organic aerosol (SOA) is a significant component of atmospheric fine particulate matter (PM2.5), and their physicochemical properties can be significantly changed in the aging process. In this study, we used a combination consisting of a smog chamber (SC) and oxidation flow reactor (OFR) to investigate the continuous aging process of gas-phase organic intermediates and SOA formed from the photooxidation of toluene, a typical aromatic hydrocarbon. Our results showed that as the OH exposure increased from 2.6 × 1011 to 6.3 × 1011 molecules cm-3 s (equivalent aging time of 2.01-4.85 days), the SOA mass concentration (2.9 ± 0.05-28.7 ± 0.6 µg cm-3) and corrected SOA yield (0.073-0.26) were significantly enhanced. As the aging process proceeds, organic acids and multiple oxygen-containing oxidation products are continuously produced from the photochemical aging process of gas-phase organic intermediates (mainly semi-volatile and intermediate volatility species, S/IVOCs). The multigeneration oxidation products then partition to the aerosol phase, while functionalization of SOA rather than fragmentation dominated in the photochemical aging process, resulting in much higher SOA yield after aging compared to that in the SC. Our study indicates that SOA yields as a function of OH exposure should be considered in air quality models to improve SOA simulation, and thus accurately assess the impact on SOA properties and regional air quality.


Assuntos
Hidrocarbonetos Aromáticos , Smog , Tolueno , Aerossóis , Oxigênio
8.
Adv Atmos Sci ; : 1-23, 2023 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-37359906

RESUMO

Atmospheric chemistry research has been growing rapidly in China in the last 25 years since the concept of the "air pollution complex" was first proposed by Professor Xiaoyan TANG in 1997. For papers published in 2021 on air pollution (only papers included in the Web of Science Core Collection database were considered), more than 24 000 papers were authored or co-authored by scientists working in China. In this paper, we review a limited number of representative and significant studies on atmospheric chemistry in China in the last few years, including studies on (1) sources and emission inventories, (2) atmospheric chemical processes, (3) interactions of air pollution with meteorology, weather and climate, (4) interactions between the biosphere and atmosphere, and (5) data assimilation. The intention was not to provide a complete review of all progress made in the last few years, but rather to serve as a starting point for learning more about atmospheric chemistry research in China. The advances reviewed in this paper have enabled a theoretical framework for the air pollution complex to be established, provided robust scientific support to highly successful air pollution control policies in China, and created great opportunities in education, training, and career development for many graduate students and young scientists. This paper further highlights that developing and low-income countries that are heavily affected by air pollution can benefit from these research advances, whilst at the same time acknowledging that many challenges and opportunities still remain in atmospheric chemistry research in China, to hopefully be addressed over the next few decades.

9.
Environ Sci Technol ; 57(23): 8671-8679, 2023 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-37235870

RESUMO

Nitrate photolysis is a vital process in secondary NOx release into the atmosphere. The heterogeneous oxidation of SO2 due to nitrate photolysis has been widely reported, while the influence of SO2 on nitrate photolysis has rarely been investigated. In this study, the photolysis of nitrate on different substrates was investigated in the absence and presence of SO2. In the photolysis of NH4NO3 on the membrane without mineral oxides, NO, NO2, HONO, and NH3 decreased by 17.1, 6.0, 12.6, and 57.1% due to the presence of SO2, respectively. In the photolysis of NH4NO3 on the surface of mineral oxides, SO2 also exhibited an inhibitory effect on the production of NOx, HONO, and NH3 due to its reducibility and acidic products, while the increase in surface acidity due to the accumulation of abundant sulfate on TiO2 and MgO promoted the release of HONO. On the photoactive oxide TiO2, HSO3-, generated by the uptake of SO2, could compete for holes with nitrate to block nitrate photolysis. This study highlights the interaction between the heterogeneous oxidation of SO2 and nitrate photolysis and provides a new perspective on how SO2 affects the photolysis of nitrate absorbed on the photoactive oxides.


Assuntos
Nitratos , Óxidos , Fotólise , Minerais
10.
Angew Chem Int Ed Engl ; 62(25): e202304017, 2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37057643

RESUMO

N2 O5 is an important intermediate in the atmospheric nitrogen cycle. Using a flow tube reactor, N2 O5 was found to be released from the TiO2 surface during the photocatalytic oxidation of NO2 , revealing a previously unreported source of N2 O5 . The rate of N2 O5 release from TiO2 was dependent on the initial NO2 concentration, relative humidity, O2 /N2 ratio, and irradiation intensity. Experimental evidence and quantum chemical calculations showed that NO2 can react with the surface hydroxyl groups and the generated electron holes on the TiO2 , followed by combining with another NO2 molecule to form N2 O5 . The latter was physisorbed on TiO2 and had a low adsorption energy of -0.13 eV. Box model simulations indicated that the new source of N2 O5 released from TiO2 can increase the daytime N2 O5 concentration by up to 20 % in urban areas if abundant TiO2 -containing materials and high NOx concentrations were present. This joint experimental/theoretical study not only demonstrates a new chemical mechanism for N2 O5 formation but also has important implications for air quality in urban areas.


Assuntos
Dióxido de Nitrogênio , Titânio , Titânio/química , Modelos Teóricos
11.
Environ Sci Technol ; 57(16): 6616-6625, 2023 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-37055378

RESUMO

Vehicular evaporative emissions make an increasing contribution to anthropogenic sources of volatile organic compounds (VOCs), thus contributing to secondary organic aerosol (SOA) formation. However, few studies have been conducted on SOA formation from vehicle evaporative VOCs under complex pollution conditions with the coexistence of NOx, SO2, and NH3. In this study, the synergistic effects of SO2 and NH3 on SOA formation from gasoline evaporative VOCs with NOx were examined using a 30 m3 smog chamber with the aid of a series of mass spectrometers. Compared with the systems involving SO2 or NH3 alone, SO2 and NH3 coexistence had a greater promotion effect on SOA formation, which was larger than the cumulative effect of the two promotions alone. Meanwhile, contrasting effects of SO2 on the oxidation state (OSc) of SOA in the presence or absence of NH3 were observed, and SO2 could further increase the OSc with the coexistence of NH3. The latter was attributed to the synergistic effects of SO2 and NH3 coexistence on SOA formation, wherein N-S-O adducts can be formed from the reaction of SO2 with N-heterocycles generated in the presence of NH3. Our study contributes to the understanding of SOA formation from vehicle evaporative VOCs under highly complex pollution conditions and its atmospheric implications.


Assuntos
Poluentes Atmosféricos , Compostos Orgânicos Voláteis , Gasolina , Aerossóis/análise , Emissões de Veículos/análise , Compostos Orgânicos Voláteis/análise , Poluição Ambiental , Poluentes Atmosféricos/análise
12.
Huan Jing Ke Xue ; 44(3): 1201-1213, 2023 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-36922183

RESUMO

Although the air quality in China has been greatly improved in recent years, the air pollution remains severe. The annual mean PM2.5 concentrations have not met the second grade of the National Ambient Air Quality Standards in China and are still much higher than the guideline value of the World Health Organization. Thus, the PM2.5 concentration needs to be further reduced. Secondary organic aerosol (SOA) is an important component of PM2.5 and has an important impact on air quality, global climate change, and human health. Therefore, understanding the formation mechanism of SOA is an important basis to control SOA and further reduce PM2.5. As an important precursor of SOA, volatile organic compounds (VOCs) can be oxidized by oxidants such as ·OH, NO3[KG-*2/3]·, Cl·, and O3 to generate low volatile organic compounds and further to form SOA through gas-particle partitioning, homogeneous nucleation, aqueous phase reaction, and heterogeneous reaction processes. The formation of SOA can be affected by many factors, such as the types and initial concentrations of VOCs, VOCs/NOx ratios, relative humidity (RH), temperature (T), seed aerosols, oxidants, aqueous phase process, and photochemical process. The observed SOA concentration is always underestimated by air quality models because a comprehensive understanding of the complexity of SOA chemical composition and formation mechanisms is still lacking, especially that under the highly complex air pollution conditions in China. Therefore, the formation mechanism and influencing factors of SOA under highly complex air pollution conditions have become an important concern in the field of atmospheric sciences. Recently, much laboratory work has focused on the formation of SOA under complex conditions. The research progress of SOA formation from different anthropogenic VOCs are reviewed here, and the methods used and the impact of different influencing factors on SOA formation are introduced. Finally, the key scientific issues that exist in the research of the SOA mechanism at present are put forward, and the future research direction is projected.

13.
Environ Sci Technol ; 57(46): 17718-17726, 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36919346

RESUMO

The heterogeneous oxidation of SO2 by NO2 has been extensively proposed as an important pathway of sulfate production during haze events in China. However, the kinetics and mechanism of oxidation of SO2 by NO2 on the surface of complex particles remain poorly understood. Here, we systematically explore the mechanism and kinetics of the reaction between SO2 and NO2 on diesel black carbon (DBC) under light irradiation. The experimental results prove that DBC photochemistry can not only significantly promote the heterogeneous reduction of NO2 to produce HONO via transferring photoinduced electrons but also indirectly promote OH radical formation. These reduction products of NO2 as well as NO2 itself greatly promote the heterogeneous oxidation of SO2 on DBC. NO2 oxidation, HONO oxidation, and the surface photo-oxidation process are proven to be three major surface oxidation pathways of SO2. The kinetics results indicate that the surface photooxidation pathway accounts for the majority of the total SO2 uptake (∼63%), followed by the HONO oxidation pathway (∼27%) and direct oxidation by NO2 (∼10%). This work highlights the significant synergistic roles of DBC, NO2, and light irradiation in enhancing the atmospheric oxidation capacity and promoting the heterogeneous formation of sulfate.


Assuntos
Dióxido de Nitrogênio , Óxidos de Enxofre , China , Oxirredução , Fuligem , Sulfatos , Carbono
14.
Environ Sci Technol ; 57(2): 920-928, 2023 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-36592345

RESUMO

TiO2 is a widely used material in building coatings. Many studies have revealed that TiO2 promotes the heterogeneous oxidation of SO2 and the subsequent sulfate formation. However, whether and how much TiO2 contributes to the gaseous H2SO4 and subsequent new particle formation (NPF) still remains unclear. Herein, we used a 1 m3 quartz smog chamber to investigate NPF in the presence of TiO2. The experimental results indicated that TiO2 could greatly promote NPF. The increases in particle formation rate (J) and growth rate due to the presence of TiO2 were quantified, and the promotion effect was attributed to the production of gaseous H2SO4. The promotion effect of TiO2 on SO2 oxidation and subsequent NPF decreased gradually due to the formation of surface sulfate but did not disappear completely, instead partly recovering after washing with water. Moreover, the promotion effect of TiO2 on NPF was observed regardless of differences in RH, and the most significant promotion effect of TiO2 associated with the strongest NPF occurred at an RH of 20%. Based on the experimental evidence, the environmental impact of TiO2 on gaseous H2SO4 and particle pollution in urban areas was estimated.


Assuntos
Poluentes Atmosféricos , Smog , Poluentes Atmosféricos/análise , Titânio , Sulfatos
15.
Sci Total Environ ; 857(Pt 3): 159538, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36270355

RESUMO

Nitrous acid (HONO) is a key precursor of the hydroxyl radicals (OH) and has a significant impact on air quality. Nowadays, the source of HONO is still controversial due to its complex formation mechanisms, which is widely explored in extensive field and laboratory studies. In this study, the pollution characteristics and source contribution of HONO under different air quality conditions in summer in Beijing were analyzed. The observation periods were classified as three typical periods: clean, ozone pollution, and double high pollution (co-occurrence of high PM2.5 and O3 concentrations). The average concentrations of observed HONO were 0.38 ± 0.35 ppb, 0.21 ± 0.18 ppb, 0.26 ± 0.20 ppb and 0.54 ± 0.45 ppb during the whole, clean, ozone and double high periods, respectively. The elevated HONO levels at night were attributed to vehicle emissions and the RH-dependent heterogeneous conversion of NO2 to HONO. The average emission ratio (HONO/NOx) was 0.85 % ± 0.38 %, and the mean value of calculated nocturnal NO2 to HONO conversion frequency was 0.0076 ± 0.0031 h-1. Based on daytime HONO budget analysis, the largest potential source of HONO was the homogeneous reaction of NO and OH (0.33 and 0.34 ppb h-1), followed by the unknown source (0.11 and 0.21 ppb h-1) during clean and ozone periods, while the unknown source (0.49 ppb h-1) played the predominant role during double high period. The unknown sources of HONO could be attributed to the photo-enhanced heterogeneous conversion of NO2 and the photolysis of particulate nitrate. Furthermore, the photolysis of ozone (0.17, 0.34 and 0.44 ppb h-1) was the major contributor to primary OH during three typical periods. HONO photolysis contributed considerable amounts of primary OH (0.32 ppb h-1) during double high period. These results are helpful to further understand the linkage between HONO and air quality variation.


Assuntos
Poluentes Atmosféricos , Ozônio , Ácido Nitroso/análise , Ozônio/análise , Dióxido de Nitrogênio/análise , Pequim , Material Particulado/análise , Poluentes Atmosféricos/análise , China
16.
Environ Sci Technol ; 56(22): 15892-15901, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36240448

RESUMO

Recent evidence has pinpointed the positive relevance between air particulate matter (PM) pollution and epidemic spread. However, there are still significant knowledge gaps in understanding the transmission and infection of pathogens loaded on PMs, for example, the interactions between pathogens and pre-existing atmospheric PM and the health effects of co-exposure on the inhalation systems. Here, we unraveled the interactions between fine particulate matter (FPM) and Pseudomonas aeruginosa (P. aeruginosa) and evaluated the infection and detrimental effects of co-exposure on the upper respiratory systems in both in vitro and in vivo models. We uncovered the higher accessibility and invasive ability of pathogens to epithelial cells after loading on FPMs, compared with the single exposure. Furthermore, we designed a novel laboratory exposure model to simulate a real co-exposure scenario. Intriguingly, the co-exposure induced more serious functional damage and longer inflammatory reactions to the upper respiratory tract, including the nasal cavity and trachea. Collectively, our results provide a new point of view on the transmission and infection of pathogens loaded on FPMs and uncover the in vivo systematic impairments of the inhalation tract under co-exposure through a novel laboratory exposure model. Hence, this study sheds light on further investigations of the detrimental effects of air pollution and epidemic spread.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Material Particulado/análise , Traqueia/química , Aerossóis e Gotículas Respiratórios , Células Epiteliais , Poluentes Atmosféricos/análise
17.
J Phys Chem Lett ; 13(44): 10335-10341, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36314658

RESUMO

Sulfate and ammonium formed on mineral dust can be mutually accelerated through the heterogeneous reactions of coexisting SO2 and NH3. However, little is known about the underlying mechanism, especially the pivotal reactive sites. Using combined Born-Oppenheimer molecular dynamics simulations and density functional theory calculations, the results show that, compared to that of SO2 or NH3 alone on the γ-Al2O3 surface, the increased level of formation of sulfate and ammonium can be attributed to the promoted activity of the surface-bridged hydroxyl with the coexistence of SO2 and NH3. In the specific mechanism, the O and H of the surface-bridged hydroxyl group are attacked by the adjacent SO2 and NH3, respectively, which directly enhances the formation of absorbed sulfite and ammonium, and indirectly facilitates the production of sulfate by oxidation of atmospheric O2. The proposed mechanisms can be broadly applied to other aluminum-based suspended dust particles, such as kaolinite, montmorillonite, and clay dust.

18.
Nat Commun ; 13(1): 5364, 2022 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-36097270

RESUMO

Both field observation and experimental simulation have implied that black carbon or soot plays a remarkable role in the catalytic oxidation of SO2 for the formation of atmospheric sulfate. However, the catalytic mechanism remains ambiguous, especially that under light irradiation. Here we systematically investigate the heterogeneous conversion of SO2 on diesel soot or black carbon (DBC) under light irradiation. The experimental results show that the presence of DBC under light irradiation can significantly promote the heterogeneous conversion of SO2 to H2SO4, mainly through the heterogeneous reaction between SO2 and photo-induced OH radicals. The detected photo-chemical behaviors on DBC suggest that OH radical formation is closely related to the abstraction and transfer of electrons in DBC and the formation of reactive superoxide radical (•O2-) as an intermediate. Our results extend the known sources of atmospheric H2SO4 and provide insight into the internal photochemical oxidation mechanism of SO2 on DBC.

19.
Environ Sci Technol ; 56(19): 13654-13663, 2022 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-36136046

RESUMO

China is facing dual pressures to reduce both PM2.5 and O3 pollution, the crucial precursors of which are NOx and VOCs. In our study, the role of NOx in both secondary organic aerosol (SOA, the important constituent of PM2.5) and O3 formation was examined in our 30 m3 indoor smog chamber. As revealed in the present study, the NOx level can obviously affect the OH concentration and volatility distribution of gas-phase oxidation products and thus O3 and SOA formation. Reducing the NOx concentration to the NOx-sensitive regime can inhibit O3 formation (by 42%), resulting in the reduction of oxidation capacity, which suppresses the SOA formation (by 45%) by inhibiting the formation of O- and N-containing gas-phase oxidation products with low volatility. The contribution of these oxidation products to the formation of SOA was also estimated, and the results could substantially support the trend of SOA yield with NOx at different VOC levels. The atmospheric implications of NOx in the coordinated control of PM2.5 and O3 are also discussed.


Assuntos
Poluentes Atmosféricos , Hidrocarbonetos Aromáticos , Ozônio , Compostos Orgânicos Voláteis , Aerossóis/análise , Poluentes Atmosféricos/análise , Ozônio/análise , Smog
20.
Small ; 18(39): e2203327, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36026535

RESUMO

Zinc (Zn) metal is considered a potential anode owing to its high theoretical capacity, safety, and low cost. However, the dendrites and corresponding side reactions in aqueous electrolytes hinder their further development in environmentally-friendly energy storage. Herein, ion-affiliative cellulose acetate (CA) coating with Zn(CF3 SO3 )2 is constructed on Zn anode (CAZ@Zn). Owing to the complexation effect between the polar ester group (CO) and Zn salt (Zn2+ ), the CAZ polymer coating enhances the hydrophilicity of the Zn anode and reduces the interfacial resistance, allowing the rapid Zn2+ diffusion and homogenizing the Zn deposition in an aqueous electrolyte to suppress zinc dendrite formation and growth. Therefore, the symmetric CAZ@Zn//CAZ@Zn battery achieves reversible plating/stripping over 2800 h at 1 mA cm-2 with 1 mAh cm-2 , about sevenfold higher than bare Zn. The full cell fabricated with an optimized Zn anode and the NH4 V4 O10 cathode achieves substantially stable performance, superior to that of bare Zn. This work provides a straightforward, effective, and scalable method to suppress the zinc dendrites and corresponding side reactions for aqueous Zn-ions batteries.


Assuntos
Ésteres , Zinco , Acetatos , Celulose/análogos & derivados , Eletrodos , Eletrólitos , Metais , Polímeros
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...