Dialkylsulfate formation in sulfuric acid-seeded secondary organic aerosol produced using an outdoor chamber under natural sunlight

Environmental context Laboratory and field studies have both provided evidence for organosulfate formation by esterification of H2SO4 with organic compounds in aerosols. Using an outdoor chamber, the production of dialkylsufate was measured for organic aerosols produced by photooxidation of various hydrocarbons in the presence of H2SO4 aerosol and NOx. The formation of organosulfates influences the decrease of both aerosol acidity and aerosol hygroscopicity. Abstract Secondary organic aerosols (SOA) were produced by the photooxidation of the volatile organic hydrocarbons (VOCs) isoprene, α-pinene and toluene, in the presence of excess amounts of sulfuric acid seed aerosol with varying NOx concentrations using a large, outdoor smog chamber. Aerosol acidity ([H+], μmol m–3) was measured using colorimetry integrated with a reflectance UV-visible spectrometer (C-RUV). The C-RUV technique measures aerosol acidity changes through the neutralisation of sulfuric acid with ammonia and the formation of dialkylsulfate, a diester of sulfuric acid. The concentration (μmol m–3) of dialkylsulfate in aerosol was estimated using the difference in [H+] obtained from C-RUV and particle-into-liquid-sampler ion chromatography (PILS-IC). The yield of dialkylsulfate (YdiOS) was defined as the dialkylsulfate concentration normalised by the concentrations of both the ammonium-free sulfate ([SO42–]free=[SO42–] – 0.5 [NH4+]) and organic carbon. The highest YdiOS appeared in isoprene SOA and the lowest YdiOS in α-pinene SOA. Under our experimental conditions, more than 50% of the total sulfates in sulfuric acid-seeded isoprene SOA were dialkylsulfates. For all SOA, higher YdiOS was observed under higher NOx conditions (VOC (ppb C)/NO (ppb)<15). Among the major functional groups (–COOH, –CO–H, –CHO and –ONO2) predicted to be present using a simple absorptive partitioning model of organic products in the multiphase system (gas, organic aerosol and inorganic aerosol), the concentrations of –CO–H, –CHO and –ONO2 groups were found to be correlated with YdiOS. In particular, a strong correlation was observed between YdiOS and the concentration of alcohol functional groups.

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Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles at moderate relative humidity

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-5677-2018 ◽

2018 ◽

Vol 18 (8) ◽

pp. 5677-5689 ◽

Cited By ~ 10

Author(s):

Tengyu Liu ◽

Dan Dan Huang ◽

Zijun Li ◽

Qianyun Liu ◽

ManNin Chan ◽

...

Keyword(s):

Relative Humidity ◽

Ammonium Sulfate ◽

Functional Groups ◽

Flow Reactor ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Aerosol Formation ◽

Seed Particles ◽

The Difference ◽

Wet Particles

Abstract. The formation of secondary organic aerosol (SOA) has been widely studied in the presence of dry seed particles at low relative humidity (RH). At higher RH, initially dry seed particles can exist as wet particles due to water uptake by the seeds as well as the SOA. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor in the absence of NOx under a range of OH exposures on initially wet or dry ammonium sulfate (AS) seed particles at an RH of 68 %. The ratio of the SOA yield on wet AS seeds to that on dry AS seeds, the relative SOA yield, decreased from 1.31 ± 0.02 at an OH exposure of 4.66 × 1010 molecules cm−3 s to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm−3 s. This decrease may be due to the early deliquescence of initially dry AS seeds after being coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW) soon after SOA formed, and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased, especially at high OH exposure. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m ∕ z 29, 43 and 44 of SOA mass spectra, obtained using an aerosol mass spectrometer (AMS), indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that inorganic dry seeds become at least partially deliquesced particles during SOA formation and hence that ALW is inevitably involved in the SOA formation at moderate RH. More laboratory experiments conducted with a wide variety of SOA precursors and inorganic seeds under different NOx and RH conditions are warranted.

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Heterogeneous uptake of NH3 on ambient PM2.5 in Beijing and Shijiazhuang: Possible influence of aerosol acidity

10.5194/egusphere-egu21-8105 ◽

2021 ◽

Author(s):

Yongchun Liu ◽

Zeming Feng ◽

Junlei Zhan ◽

Xiaolei Bao

Keyword(s):

Sulfuric Acid ◽

Organic Aerosol ◽

Uptake Coefficient ◽

Natural Ecosystems ◽

Aerosol Acidity ◽

Ice Surface ◽

Aqueous Surface ◽

Organic Gases ◽

Global Emissions ◽

Urban Sites

Ammonium salts (NH4+) is the important component of PM2.5 and has a significant impact on air quality, climate, human health, and natural ecosystems. The contribution of NH4+ to PM2.5 is increasing at urban sites. Ammonia (NH3) with global emissions estimated at greater than 33 Tg(N) Yr-1 is the only precursor of particulate NH4+ in the atmosphere. Thus, it is important to understand the conversion kinetics from NH3 to NH4+ in the atmosphere. However, the uptake coefficient of NH3 (&#947;NH3) on aerosol particles are scarce at the present time. In this work, we reported the &#947;NH3 on ambient PM2.5 in Beijing and Shijiazhuang in China. The &#947;NH3 values on ambient PM2.5 are (1.13&#177;12.4)&#215;10-4 and (6.88&#177;40.7)&#215;10-4 in Shijiazhuang and Beijing, respectively. They are significantly lower than those on sulfuric acid droplet (0.1-1), aqueous surface (~5&#215;10-3-0.1) and acidified secondary organic aerosol (~10-3-~10-2), while are comparable with that on ice surface (5.3&#177;2.2 &#215;10-4) and on sulfuric acid in the presence of organic gases (2&#215;10-4-4&#215;10-3). An annual increase of &#947;NH3 in the statistic sense is observed and the possible reason related to the aerosol acidity has also been discussed.

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Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles

10.5194/acp-2017-1008 ◽

2017 ◽

Cited By ~ 1

Author(s):

Tengyu Liu ◽

Dan Dan Huang ◽

Zijun Li ◽

Qianyun Liu ◽

ManNin Chan ◽

...

Keyword(s):

Ammonium Sulfate ◽

Functional Groups ◽

Flow Reactor ◽

Secondary Organic Aerosol ◽

Large Fraction ◽

Organic Aerosol ◽

Aerosol Formation ◽

Seed Particles ◽

The Difference ◽

Wet Particles

Abstract. The formation of secondary organic aerosol (SOA) has been widely studied in the presence of dry seed particles at low relative humidity (RH). At higher RH, seed particles can exist as dry or wet particles. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor under a range of OH exposures on initially wet or dry ammonium sulfate (AS) seed particles at an RH of 68 %. At an OH exposure of 4.66 × 1010 molecules cm -3 s, the ratio of the SOA yield on wet AS seeds to that on dry AS seeds was 1.31 ± 0.02. However, this ratio decreased to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm -3 s. The decrease in the ratios of SOA yields as the increase of OH exposure may be due to the early deliquescence of initially dry AS seeds after coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW) soon after a large fraction of SOA formed and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m/z 29, 43 and 44 of SOA mass spectra indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that AS dry seeds soon turn to at least partially deliquesced particles during SOA formation and more studies on the interplay of SOA formation and ALW are warranted.

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Implementing marine organic aerosols into the GEOS-Chem model

Geoscientific Model Development ◽

10.5194/gmd-8-619-2015 ◽

2015 ◽

Vol 8 (3) ◽

pp. 619-629 ◽

Cited By ~ 8

Author(s):

B. Gantt ◽

M. S. Johnson ◽

M. Crippa ◽

A. S. H. Prévôt ◽

N. Meskhidze

Keyword(s):

Cloud Condensation Nuclei ◽

Organic Aerosols ◽

Field Studies ◽

Organic Aerosol ◽

Tropospheric Chemistry ◽

Surface Mass ◽

Earth Observing System ◽

Aerosol Mass ◽

Aerosol Mass Concentration ◽

Aerosol Emission

Abstract. Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from −79% when using the default settings to −12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of −36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

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Physico-chemical characterization of secondary organic aerosol derived from catechol and guaiacol as a model substance for atmospheric humic-like substances

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-17369-2010 ◽

2010 ◽

Vol 10 (7) ◽

pp. 17369-17405 ◽

Cited By ~ 3

Author(s):

J. Ofner ◽

H.-U. Krüger ◽

H. Grothe ◽

P. Schmitt-Kopplin ◽

K. Whitmore ◽

...

Keyword(s):

Functional Groups ◽

Mass Spectroscopy ◽

Secondary Organic Aerosols ◽

Secondary Organic Aerosol ◽

Organic Aerosols ◽

Organic Aerosol ◽

Chemical Diversity ◽

Spherical Particles ◽

Aerosol Formation ◽

Vis Spectroscopy

Abstract. Secondary organic aerosol was produced from the aromatic precursors catechol and guaiacol by reaction with ozone in the presence and absence of simulated sunlight and humidity and investigated for its properties as a proxy for humic-like substances (HULIS). Beside a small particle size, a relatively low molecular weight and typical optical features in the UV/VIS spectral range, HULIS contain a typical aromatic and/or olefinic chemical structure and highly oxidized functional groups within a high chemical diversity. Various methods were used to characterize the secondary organic aerosols obtained: Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of different carbonyl containing functional groups as well as structural and functional differences between aerosols formed at different environmental conditions. UV/VIS spectroscopy of filter samples showed that the particulate matter absorbs far into the visible range up to more than 500 nm. Ultrahigh resolved mass spectroscopy (ICR-FT/MS) determined O/C-ratios between 0.3 and 1 and main molecular weights between 200 and 500 Da. Temperature-programmed-pyrolysis mass spectroscopy identified carboxylic acids and lactones as major functional groups. Particle sizing using CNC-DMPS demonstrated the formation of small particles during a secondary organic aerosol formation process. Particle imaging using field-emission-gun scanning electron microscopy (FEG-SEM) showed spherical particles, forming clusters and chains. Hence, secondary organic aerosols from catechol and guaiacol are appropriate model substances for studies of the processing of aromatic secondary organic aerosols and atmospheric HULIS on the laboratory scale.

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Secondary organic aerosol formation from methacrolein photooxidation: roles of NOx level, relative humidity and aerosol acidity

Environmental Chemistry ◽

10.1071/en12004 ◽

2012 ◽

Vol 9 (3) ◽

pp. 247 ◽

Cited By ~ 48

Author(s):

Haofei Zhang ◽

Ying-Hsuan Lin ◽

Zhenfa Zhang ◽

Xiaolu Zhang ◽

Stephanie L. Shaw ◽

...

Keyword(s):

Mass Spectrometry ◽

Global Climate ◽

Organic Aerosols ◽

Organic Aerosol ◽

Atmospheric Particulate Matter ◽

Gas Chromatography Mass Spectrometry ◽

Aerosol Formation ◽

Aerosol Acidity ◽

Volatile Organic ◽

Dry Conditions

Environmental contextSecondary organic aerosols formed from the oxidation of volatile organic compounds make a significant contribution to atmospheric particulate matter, which in turn affects both global climate change and human health. We investigate the mechanisms of formation and the chemical properties of secondary organic aerosols derived from isoprene, the most abundant non-methane-based, volatile organic compound emitted into the Earth’s atmosphere. However, the exact manner in which these aerosols are formed, and how they are affected by environmental conditions, remains unclear. AbstractSecondary organic aerosol (SOA) formation from the photooxidation of methacrolein (MACR) was examined in a dual outdoor smog chamber under varied initial nitric oxide (NO) levels, relative humidities (RHs) and seed aerosol acidities. Aerosol sizing measurements and off-line chemical analyses by gas chromatography/mass spectrometry and ultra performance liquid chromatography/electrospray ionisation high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS) were used to characterise MACR SOA formation. Results indicate that both SOA mass and chemical composition largely depend on the initial MACR/NO ratio and RH conditions. Specifically, at lower initial NO levels (MACR/NO = ~2.7) more substantial SOA is formed under dry conditions (5–20 % RH) compared to wet conditions (30–80 % RH). However, at higher initial NO levels (MACR/NO = ~0.9), the maximum SOA formation was marginally higher under wet conditions. Furthermore, UPLC/ESI-HR-Q-TOFMS data suggest that most particle-phase oligomers, which have been previously observed to form from the oxidation of methacryloylperoxynitrate, were enhanced under dry conditions. In addition to 2-methylglyceric acid and organosulfates derived from MACR oxidation, a nitrogen-containing organic tracer compound was found to form substantially in both chamber-generated and ambient aerosol samples collected from downtown Atlanta, GA, during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS). Moreover, increasing aerosol acidity because of additional sulfuric acid appears to have a negligible effect on both SOA mass and most SOA constituents. Nevertheless, increased RH and aerosol acidity were both observed to enhance organosulfate formation; however, elevating RH mediates organosulfate formation, suggesting that wet sulfate aerosols are necessary to form organosulfates in atmospheric aerosols.

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THE HA ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

Canadian Journal of Chemistry ◽

10.1139/v65-314 ◽

1965 ◽

Vol 43 (8) ◽

pp. 2328-2335 ◽

Cited By ~ 32

Author(s):

Keith Yates ◽

J. C. Riordan

Keyword(s):

Sulfuric Acid ◽

Hydrochloric Acid ◽

Acidity Function ◽

Rate Data ◽

High Concentration ◽

Concentration Region ◽

Experimental Conditions ◽

Activity Data ◽

Amide Hydrolysis ◽

The Difference

Values of the HA acidity function have been determined for 0–35% hydrochloric acid using a set of amide indicators. The indicator pK values agree with those previously obtained in sulfuric acid. The HA scale decreases less steeply than H0 in the high concentration region, but the difference between the two functions is less marked than in sulfuric acid. The reasons for this are discussed. The values of HA have been combined with available rate and water activity data to obtain information about the mechanism of amide hydrolysis. Eleven sets of rate data, consisting of 64 rate constants obtained under a variety of experimental conditions, give similar hydration parameters for this reaction. The temperature dependence of hydration parameters is discussed.

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Implementing marine organic aerosols into the GEOS-Chem model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-5965-2014 ◽

2014 ◽

Vol 7 (5) ◽

pp. 5965-5992

Author(s):

B. Gantt ◽

M. S. Johnson ◽

M. Crippa ◽

A. S. H. Prévôt ◽

N. Meskhidze

Keyword(s):

Cloud Condensation Nuclei ◽

Organic Aerosols ◽

Field Studies ◽

Organic Aerosol ◽

Tropospheric Chemistry ◽

Surface Mass ◽

Ice Nuclei ◽

Aerosol Mass ◽

Aerosol Mass Concentration ◽

Aerosol Emission

Abstract. Marine organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from −79% when using the default settings to −12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of −36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

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Potential Pitfalls in Membrane Fouling Evaluation: Merits of Data Representation as Resistance Instead of Flux Decline in Membrane Filtration

Membranes ◽

10.3390/membranes11070460 ◽

2021 ◽

Vol 11 (7) ◽

pp. 460

Author(s):

Bastiaan Blankert ◽

Bart Van der Bruggen ◽

Amy E. Childress ◽

Noreddine Ghaffour ◽

Johannes S. Vrouwenvelder

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Data Representation ◽

Strong Impact ◽

Experimental Conditions ◽

Permeable Membrane ◽

Dead End ◽

Flux Decline ◽

The Difference ◽

Filtration Flux

The manner in which membrane-fouling experiments are conducted and how fouling performance data are represented have a strong impact on both how the data are interpreted and on the conclusions that may be drawn. We provide a couple of examples to prove that it is possible to obtain misleading conclusions from commonly used representations of fouling data. Although the illustrative example revolves around dead-end ultrafiltration, the underlying principles are applicable to a wider range of membrane processes. When choosing the experimental conditions and how to represent fouling data, there are three main factors that should be considered: (I) the foulant mass is principally related to the filtered volume; (II) the filtration flux can exacerbate fouling effects (e.g., concentration polarization and cake compression); and (III) the practice of normalization, as in dividing by an initial value, disregards the difference in driving force and divides the fouling effect by different numbers. Thus, a bias may occur that favors the experimental condition with the lower filtration flux and the less-permeable membrane. It is recommended to: (I) avoid relative fouling performance indicators, such as relative flux decline (J/J0); (II) use resistance vs. specific volume; and (III) use flux-controlled experiments for fouling performance evaluation.

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Determining the Role of Acidity, Fate and Formation of IEPOX-Derived SOA in CMAQ

Atmosphere ◽

10.3390/atmos12060707 ◽

2021 ◽

Vol 12 (6) ◽

pp. 707

Author(s):

Petros Vasilakos ◽

Yongtao Hu ◽

Armistead Russell ◽

Athanasios Nenes

Keyword(s):

Significant Influence ◽

Organic Aerosol ◽

Liquid Water Content ◽

Anthropogenic Emissions ◽

So2 Emissions ◽

Aerosol Acidity ◽

A Value ◽

Future Emission ◽

The Impact

Formation of aerosol from biogenic hydrocarbons relies heavily on anthropogenic emissions since they control the availability of species such as sulfate and nitrate, and through them, aerosol acidity (pH). To elucidate the role that acidity and emissions play in regulating Secondary Organic Aerosol (SOA), we utilize the 2013 Southern Oxidant and Aerosol Study (SOAS) dataset to enhance the extensive mechanism of isoprene epoxydiol (IEPOX)-mediated SOA formation implemented in the Community Multiscale Air Quality (CMAQ) model (Pye et al., 2013), which was then used to investigate the impact of potential future emission controls on IEPOX OA. We found that the Henry’s law coefficient for IEPOX was the most impactful parameter that controls aqueous isoprene OA products, and a value of 1.9 × 107 M atm−1 provides the best agreement with measurements. Non-volatile cations (NVCs) were found in higher-than-expected quantities in CMAQ and exerted a significant influence on IEPOX OA by reducing its production by as much as 30% when present. Consistent with previous literature, a strong correlation of isoprene OA with sulfate, and little correlation with acidity or liquid water content, was found. Future reductions in SO2 emissions are found to not affect this correlation and generally act to increase the sensitivity of IEPOX OA to sulfate, even in extreme cases.

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