Aerosol fast flow reactor for laboratory studies of new particle formation

Ezell, M. J.; Chen, Haihan; Arquero, Kristine D.; Finlayson-Pitts, Barbara J.

doi:10.1016/j.jaerosci.2014.08.009

Cited by 23 publications

(31 citation statements)

References 38 publications

(41 reference statements)

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“…During periods when the CS entering the OFR in ambient air was larger, it reduced the condensation of SOA onto new particles, consistent with the lower importance of this mode for an OFR study in the Los Angeles area . These results support the possibility of using flow reactors to study the potential for new particle formation and growth in different ambient air masses and sources (Ezell et al, 2014;Chen et al, 2015).…”

Section: Condensation Vs Nucleation In the Ofrsupporting

confidence: 74%

In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

et al. 2016

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Abstract. An oxidation flow reactor (OFR) is a vessel inside which the concentration of a chosen oxidant can be increased for the purpose of studying SOA formation and aging by that oxidant. During the BEACHON-RoMBAS (Bio-hydroatmosphere interactions of Energy, Aerosols, Carbon, H 2 O, Organics & Nitrogen-Rocky Mountain Biogenic Aerosol Study) field campaign, ambient pine forest air was oxidized by OH radicals in an OFR to measure the amount of SOA that could be formed from the real mix of ambient SOA precursor gases, and how that amount changed with time as precursors changed. High OH concentrations and short residence times allowed for semicontinuous cycling through a large range of OH exposures ranging from hours to weeks of equivalent (eq.) atmospheric aging. A simple model is derived and used to account for the relative timescales of condensation of low-volatility organic compounds (LVOCs) onto particles; condensational loss to the walls; and further reaction to produce volatile, non-condensing fragmentation products. More SOA production was observed in the OFR at nighttime (average 3 µg m −3 when LVOC fate corrected) compared to daytime (average 0.9 µg m −3 when LVOC fate corrected), with maximum formation observed at 0.4-1.5 eq. days of photochemical aging. SOA formation followed a similar diurnal pattern to monoterpenes, sesquiterpenes, and toluene+p-cymene concentrations, including a substantial increase just after sunrise at 07:00 local time. Higher photochemical aging (> 10 eq. days) led to a decrease in new SOA formation and a loss of preexisting OA due to heterogeneous oxidation followed by fragmentation and volatilization. When comparing two different commonly used methods of OH production in OFRs (OFR185 and OFR254-70), similar amounts of SOA formation were observed. We recommend the OFR185 mode for future forest studies. Concurrent gas-phase measurements of air after OH oxidation illustrate the decay of primary VOCs, production of small oxidized organic compounds, and net production at lower ages followed by net consumption of terpenoid oxidation products as photochemical age increased. New particle formation was observed in the reactor after oxidation, especially during times when precursor gas concentrations and SOA formation were largest. Approximately 4.4 times more SOA was formed in the reactor from OH oxidation than could be explained by the VOCs measured in ambient air. To our knowledge this is the first time that this has been shown when comparing VOC concentrations with SOA formation measured at the same time, rather than comparing measurements made at different times. An SOA yield of 18-58 % from those compounds can explain the observed SOA formation. S/IVOCs were the only pool of gas-phase carbon that was large enough to explain the observed SOA formation. This work suggests that these typically unmeasured gases play a substantial role in ambient SOA formation. Our results allow ruling out condensation sticking coefficients much lower than 1. These measurements help clarify the magnitu...

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Section: Condensation Vs Nucleation In the Ofrsupporting

confidence: 74%

In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

et al. 2016

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“…The North Atlantic Aerosols and Marine Ecosystems Study NAAMES campaign has elucidated the contribution of NPF involving sulfur to CCN concentrations in the marine atmosphere (Sanchez et al, ). In addition to sulfuric acid, methanesulfonic acid (MSA) formed from oxidation of dimethyl sulfide (DMS) may contribute to NPF, as shown by CNT calculations (Kreidenweis et al, ), quantum chemical calculations (Bork et al, ; Wen et al, ), and flow tube experiments (Chen et al, ; Dawson et al, ; Ezell et al, ). Although MSA concentrations are comparable to sulfuric acid in the marine boundary layer, laboratory measurements showed that J of binary nucleation of MSA and water are relatively small (Wyslouzil et al, ).…”

Section: Npf Observations In Various Environmentsmentioning

confidence: 99%

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

et al. 2019

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New particle formation (NPF) represents the first step in the complex processes leading to formation of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, and outlines the challenges and future directions for research relevant to NPF. New developments include the emergence of state‐of‐the‐art instruments that measure prenucleation clusters and newly nucleated nanoparticles down to about 1 nm; systematic laboratory studies of multicomponent nucleation systems, including collaborative experiments conducted in the Cosmics Leaving Outdoor Droplets chamber at CERN; observations of NPF in different types of forests, extremely polluted urban locations, coastal sites, polar regions, and high‐elevation sites; and improved nucleation theories and parameterizations to account for NPF in atmospheric models. The challenges include the lack of understanding of the fundamental chemical mechanisms responsible for aerosol nucleation and growth under diverse environments, the effects of SO2 and NOx on NPF, and the contribution of anthropogenic organic compounds to NPF. It is also critical to develop instruments that can detect chemical composition of particles from 3 to 20 nm and improve parameterizations to represent NPF over a wide range of atmospheric conditions of chemical precursor, temperature, and humidity.

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“…Experiments were performed in a small volume (∼6.6 L) aerosol flow reactor ( Figure 1) similar in design to that described elsewhere. 80 The flow reactor has multiple inlets: three fixed rings upstream and three spokes, movable as a unit, downstream. Details of the flow reactor and determination of residence times are in Section 1 of the Supporting Information.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

The Role of Oxalic Acid in New Particle Formation from Methanesulfonic Acid, Methylamine, and Water

Arquero

Gerber

Finlayson-Pitts

2017

Environ. Sci. Technol.

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Atmospheric particles are notorious for their effects on human health and visibility and are known to influence climate. Though sulfuric acid and ammonia/amines are recognized as main contributors to new particle formation (NPF), models and observations have indicated that other species may be involved. It has been shown that nucleation from methanesulfonic acid (MSA) and amines, which is enhanced with added water, can also contribute to NPF. While organics are ubiquitous in air and likely to be involved in NPF by stabilizing small clusters for further growth, their effects on the MSA-amine system are not known. This work investigates the effect of oxalic acid (OxA) on NPF from the reaction of MSA and methylamine (MA) at 1 atm and 294 K in the presence and absence of water vapor using an aerosol flow reactor. OxA and MA do not efficiently form particles even in the presence of water, but NPF is enhanced when adding MSA to OxA-MA with and without water. The addition of OxA to MSA-MA mixtures yields a modest NPF enhancement, whereas the addition of OxA to MSA-MA-HO has no effect. Possible reasons for these effects are discussed.

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Aerosol fast flow reactor for laboratory studies of new particle formation

Cited by 23 publications

References 38 publications

In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

In situ secondary organic aerosol formation from ambient pine forest air using an oxidation flow reactor

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

The Role of Oxalic Acid in New Particle Formation from Methanesulfonic Acid, Methylamine, and Water

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