1
|
Milsom A, Squires AM, Macklin J, Wady P, Pfrang C. Acoustic levitation combined with laboratory-based small-angle X-ray scattering (SAXS) to probe changes in crystallinity and molecular organisation. RSC Adv 2024; 14:17519-17525. [PMID: 38818358 PMCID: PMC11138859 DOI: 10.1039/d4ra01418a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 05/23/2024] [Indexed: 06/01/2024] Open
Abstract
Single particle levitation techniques allow us to probe samples in a contactless way, negating the effect that surfaces could have on processes such as crystallisation and phase transitions. Small-angle X-ray scattering (SAXS) is a common method characterising the nanoscale order in aggregates such as colloidal, crystalline and liquid crystalline systems. Here, we present a laboratory-based small-angle X-ray scattering (SAXS) setup combined with acoustic levitation. The capability of this technique is highlighted and compared with synchrotron-based levitation-SAXS and X-ray diffraction. We were able to follow the deliquescence and crystallisation of sucrose, a commonly used compound for the study of viscous atmospheric aerosols. The observed increased rate of the deliquescence-crystallisation transitions on repeated cycling could suggest the formation of a glassy sucrose phase. We also followed a reversible phase transition in an oleic acid-based lyotropic liquid crystal system under controlled humidity changes. Our results demonstrate that the coupling of acoustic levitation with an offline SAXS instrument is feasible, and that the time resolution and data quality are sufficient to draw physically meaningful conclusions. There is a wide range of potential applications including topics such as atmospheric aerosol chemistry, materials science, crystallisation and aerosol spray drying.
Collapse
Affiliation(s)
- Adam Milsom
- School of Geography, Earth and Environmental Sciences, University of Birmingham Edgbaston B15 2TT Birmingham UK
| | - Adam M Squires
- Department of Chemistry, University of Bath South Building, Soldier Down Ln, Claverton Down BA2 7AX Bath UK
| | - Jack Macklin
- Department of Chemistry, University of Bath South Building, Soldier Down Ln, Claverton Down BA2 7AX Bath UK
| | - Paul Wady
- Diamond Light Source, Diamond House Harwell Science and Innovation Campus OX11 0DE Didcot UK
| | - Christian Pfrang
- School of Geography, Earth and Environmental Sciences, University of Birmingham Edgbaston B15 2TT Birmingham UK
- Department of Meteorology, University of Reading Whiteknights, Earley Gate RG6 6BB Reading UK
| |
Collapse
|
2
|
Ahmed M, Lu W. Probing Complex Chemical Processes at the Molecular Level with Vibrational Spectroscopy and X-ray Tools. J Phys Chem Lett 2023; 14:9265-9278. [PMID: 37812752 DOI: 10.1021/acs.jpclett.3c02263] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Understanding the origins of structure and bonding at the molecular level in complex chemical systems spanning magnitudes in length and time is of paramount interest in physical chemistry. We have coupled vibrational spectroscopy and X-ray based techniques with a series of microreactors and aerosol beams to tease out intricate and sometimes subtle interactions, such as hydrogen bonding, proton transfer, and noncovalent interactions. This allows for unraveling the self-assembly of arginine-oleic acid complexes in an aqueous solution and growth processes in a metal-organic framework. Terahertz and infrared spectroscopy provide an intimate view of the hydrogen-bond network and associated phase changes with temperature in neopentyl glycol. The hydrogen-bond network in aqueous glycerol aerosols and levels of protonation of nicotine in aqueous aerosols are visualized. Future directions in probing the hydrogen-bond networks in deep eutectic solvents and organic frameworks are described, and we suggest how X-ray scattering coupled to X-ray spectroscopy can offer insight into the reactivity of organic aerosols.
Collapse
Affiliation(s)
- Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- CSIRO Environment, Urrbrae, South Australia 5064, Australia
| |
Collapse
|
3
|
Milsom A, Squires AM, Ward AD, Pfrang C. Molecular Self-Organization in Surfactant Atmospheric Aerosol Proxies. Acc Chem Res 2023; 56:2555-2568. [PMID: 37688543 PMCID: PMC10552546 DOI: 10.1021/acs.accounts.3c00194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Indexed: 09/11/2023]
Abstract
ConspectusAerosols are ubiquitous in the atmosphere. Outdoors, they take part in the climate system via cloud droplet formation, and they contribute to indoor and outdoor air pollution, impacting human health and man-made environmental change. In the indoor environment, aerosols are formed by common activities such as cooking and cleaning. People can spend up to ca. 90% of their time indoors, especially in the western world. Therefore, there is a need to understand how indoor aerosols are processed in addition to outdoor aerosols.Surfactants make significant contributions to aerosol emissions, with sources ranging from cooking to sea spray. These molecules alter the cloud droplet formation potential by changing the surface tension of aqueous droplets and thus increasing their ability to grow. They can also coat solid surfaces such as windows ("window grime") and dust particles. Such surface films are more important indoors due to the higher surface-to-volume ratio compared to the outdoor environment, increasing the likelihood of surface film-pollutant interactions.A common cooking and marine emission, oleic acid, is known to self-organize into a range of 3-D nanostructures. These nanostructures are highly viscous and as such can impact the kinetics of aerosol and film aging (i.e., water uptake and oxidation). There is still a discrepancy between the longer atmospheric lifetime of oleic acid compared with laboratory experiment-based predictions.We have created a body of experimental and modeling work focusing on the novel proposition of surfactant self-organization in the atmosphere. Self-organized proxies were studied as nanometer-to-micrometer films, levitated droplets, and bulk mixtures. This access to a wide range of geometries and scales has resulted in the following main conclusions: (i) an atmospherically abundant surfactant can self-organize into a range of viscous nanostructures in the presence of other compounds commonly encountered in atmospheric aerosols; (ii) surfactant self-organization significantly reduces the reactivity of the organic phase, increasing the chemical lifetime of these surfactant molecules and other particle constituents; (iii) while self-assembly was found over a wide range of conditions and compositions, the specific, observed nanostructure is highly sensitive to mixture composition; and (iv) a "crust" of product material forms on the surface of reacting particles and films, limiting the diffusion of reactive gases to the particle or film bulk and subsequent reactivity. These findings suggest that hazardous, reactive materials may be protected in aerosol matrixes underneath a highly viscous shell, thus extending the atmospheric residence times of otherwise short-lived species.
Collapse
Affiliation(s)
- Adam Milsom
- School
of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
| | - Adam M. Squires
- Department
of Chemistry, University of Bath, South Building, Soldier Down Ln,
Claverton Down, Bath BA2
7AY, U.K.
| | - Andrew D. Ward
- STFC
Rutherford Appleton Laboratory, Central
Laser Facility, Didcot OX11 0FA, U.K.
| | - Christian Pfrang
- School
of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
- Department
of Meteorology, University of Reading, Whiteknights, Earley Gate, Reading RG6 6UR, U.K.
| |
Collapse
|
4
|
In situ Raman and X-ray scattering of a single supersaturated aqueous Mg(NO 3) 2 droplet ultrasonically levitated. ANAL SCI 2023; 39:977-987. [PMID: 36856988 DOI: 10.1007/s44211-023-00306-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/13/2023] [Indexed: 03/02/2023]
Abstract
A single liquid droplet in the air generated by ultrasonic levitation provides such analytical advantages as a small sample volume (~ μL) for expensive proteins, container-free condition for deeply supercooling and supersaturation, time-dependent observation, and homogeneous rapid mixing. The investigation of the properties and structure of a droplet at a molecular level is highly needed for understanding the physicochemical behaviors of a droplet and an underlying mechanism of processes in the droplet. We develop in situ Raman and synchrotron X-ray scattering methods of a single liquid droplet of ~ 1 mm size ultrasonically levitated. The composition of a supersaturated Mg(NO3)2 droplet and speciation in the droplet are determined by analyzing the nitrate N-O and the water O-H stretching vibrational Raman bands. The X-ray interference function of an supersaturated Mg(NO3)2 droplet is subjected to an empirical potential structure refinement modeling to reveal the ion solvation, association, and solvent water structure. Furthermore, crystallization of Mg(NO3)2⋅nH2O from a saturated droplet is observed and identified.
Collapse
|
5
|
Rissler J, Preger C, Eriksson AC, Lin JJ, Prisle NL, Svenningsson B. Missed Evaporation from Atmospherically Relevant Inorganic Mixtures Confounds Experimental Aerosol Studies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2706-2714. [PMID: 36758144 PMCID: PMC9948290 DOI: 10.1021/acs.est.2c06545] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Sea salt aerosol particles are highly abundant in the atmosphere and play important roles in the global radiative balance. After influence from continental air, they are typically composed of Na+, Cl-, NH4+, and SO42- and organics. Analogous particle systems are often studied in laboratory settings by atomizing and drying particles from a solution. Here, we present evidence that such laboratory studies may be consistently biased in that they neglect losses of solutes to the gas phase. We present experimental evidence from a hygroscopic tandem differential mobility analyzer and an aerosol mass spectrometer, further supported by thermodynamic modeling. We show that, at normally prevailing laboratory aerosol mass concentrations, for mixtures of NaCl and (NH4)2SO4, a significant portion of the Cl- and NH4+ ions are lost to the gas phase, in some cases, leaving mainly Na2SO4 in the dry particles. Not considering losses of solutes to the gas phase during experimental studies will likely result in misinterpretation of the data. One example of such data is that from particle water uptake experiments. This may bias the explanatory models constructed from the data and introduce errors inte predictions made by air quality or climate models.
Collapse
Affiliation(s)
- Jenny Rissler
- Ergonomics
and Aerosol Technology, Lund University, Box 118, 221 00 Lund, Sweden
- Bioeconomy
and Health, Research Institutes of Sweden
(RISE), Scheelevägen
17, 223 70 Lund, Sweden
| | - Calle Preger
- Ergonomics
and Aerosol Technology, Lund University, Box 118, 221 00 Lund, Sweden
- MAX
IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden
| | - Axel C. Eriksson
- Ergonomics
and Aerosol Technology, Lund University, Box 118, 221 00 Lund, Sweden
| | - Jack J. Lin
- Center
for Atmospheric Research, University of
Oulu, P.O. Box 4500, 90014 Oulu, Finland
| | - Nønne L. Prisle
- Center
for Atmospheric Research, University of
Oulu, P.O. Box 4500, 90014 Oulu, Finland
| | | |
Collapse
|
6
|
Estefany C, Sun Z, Hong Z, Du J. Raman spectroscopy for profiling physical and chemical properties of atmospheric aerosol particles: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 249:114405. [PMID: 36508807 DOI: 10.1016/j.ecoenv.2022.114405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Atmosphere aerosols have significant impact on human health and the environment. Aerosol particles have a number of characteristics that influence their health and environmental effects, including their size, shape, and chemical composition. A great deal of difficulty is associated with quantifying and identifying atmospheric aerosols because these parameters are highly variable on a spatial and temporal scale. An important component of understanding aerosol fate is Raman Spectroscopy (RS), which is capable of resolving chemical compositions of individual particles. This review presented strategic techniques, especially RS methods for characterizing atmospheric aerosols. The nature and properties of atmospheric aerosols and their influence on environment and human health were briefly described. Analytical methodologies that offer insight into the chemistry and multidimensional properties of aerosols were discussed. In addition, perspectives for practical applications of atmospheric aerosols using RS are featured.
Collapse
Affiliation(s)
- Cedeño Estefany
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Key Laboratory of Resources and Environmental System Optimization of Ministry of Education, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Zhenli Sun
- Key Laboratory of Resources and Environmental System Optimization of Ministry of Education, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Zijin Hong
- Key Laboratory of Resources and Environmental System Optimization of Ministry of Education, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China
| | - Jingjing Du
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| |
Collapse
|
7
|
Milsom A, Squires AM, Quant I, Terrill NJ, Huband S, Woden B, Cabrera-Martinez ER, Pfrang C. Exploring the Nanostructures Accessible to an Organic Surfactant Atmospheric Aerosol Proxy. J Phys Chem A 2022; 126:7331-7341. [PMID: 36169656 PMCID: PMC9574911 DOI: 10.1021/acs.jpca.2c04611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
![]()
The composition of atmospheric aerosols varies with time,
season,
location, and environment. This affects key aerosol properties such
as hygroscopicity and reactivity, influencing the aerosol’s
impact on the climate and air quality. The organic fraction of atmospheric
aerosol emissions often contains surfactant material, such as fatty
acids. These molecules are known to form three-dimensional nanostructures
in contact with water. Different nanostructures have marked differences
in viscosity and diffusivity that are properties whose understanding
is essential when considering an aerosol’s atmospheric impact.
We have explored a range of nanostructures accessible to the organic
surfactant oleic acid (commonly found in cooking emissions), simulating
variation that is likely to happen in the atmosphere. This was achieved
by changing the amount of water, aqueous phase salinity and by addition
of other commonly coemitted compounds: sugars and stearic acid (the
saturated analogue of oleic acid). The nanostructure was observed
by both synchrotron and laboratory small/wide angle X-ray scattering
(SAXS/WAXS) and found to be sensitive to the proxy composition. Additionally,
the spacing between repeat units in these nanostructures was water
content dependent (i.e., an increase from 41 to 54 Å in inverse
hexagonal phase d-spacing when increasing the water
content from 30 to 50 wt %), suggesting incorporation of water within
the nanostructure. A significant decrease in mixture viscosity was
also observed with increasing water content from ∼104 to ∼102 Pa s when increasing the water content
from 30 to 60 wt %. Time-resolved SAXS experiments on levitated droplets
of this proxy confirm the phase changes observed in bulk phase mixtures
and demonstrate that coexistent nanostructures can form in droplets.
Aerosol compositional and subsequent nanostructural changes could
affect aerosol processes, leading to an impact on the climate and
urban air pollution.
Collapse
Affiliation(s)
- Adam Milsom
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston B15 2TT, Birmingham, United Kingdom
| | - Adam M Squires
- Department of Chemistry, University of Bath, South Building, Soldier Down Ln, Claverton Down BA2 7AX, Bath, United Kingdom
| | - Isabel Quant
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Nicholas J Terrill
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, OX11 0DE, Didcot, United Kingdom
| | - Steven Huband
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Ben Woden
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
| | - Edna R Cabrera-Martinez
- Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom
| | - Christian Pfrang
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston B15 2TT, Birmingham, United Kingdom.,Department of Meteorology, University of Reading, Whiteknights, Earley Gate, RG6 6BB, Reading, United Kingdom
| |
Collapse
|
8
|
Inverse ISAsomes in Bio-Compatible Oils—Exploring Formulations in Squalane, Triolein and Olive Oil. NANOMATERIALS 2022; 12:nano12071133. [PMID: 35407249 PMCID: PMC9000821 DOI: 10.3390/nano12071133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 03/26/2022] [Accepted: 03/28/2022] [Indexed: 11/17/2022]
Abstract
In contrast to their more common counterparts in aqueous solutions, inverse ISAsomes (internally self-assembled somes/particles) are formulated as kinetically stabilised dispersions of hydrophilic, lyotropic liquid-crystalline (LC) phases in non-polar oils. This contribution reports on their formation in bio-compatible oils. We found that it is possible to create inverse hexosomes, inverse micellar cubosomes (Fd3m) and an inverse emulsified microemulsion (EME) in excess squalane with a polyethylene glycol alkyl ether as the primary surfactant forming the LC phase and to stabilise them with hydrophobised silica nanoparticles. Furthermore, an emulsified -phase and inverse hexosomes were formed in excess triolein with the triblock-copolymer Pluronic® P94 as the primary surfactant. Stabilisation was achieved with a molecular stabiliser of type polyethylene glycol (PEG)-dipolyhydroxystearate. For the inverse hexosomes in triolein, the possibility of a formulation without any additional stabiliser was explored. It was found that a sufficiently strong stabilisation effect was created by the primary surfactant alone. Finally, triolein was replaced with olive oil which also led to the successful formation of inverse hexosomes. As far as we know, there exists no previous contribution about inverse ISAsomes in complex oils such as triolein or plant oils, and the existence of stabiliser-free (i.e., self-stabilising) inverse hexosomes has also not been reported until now.
Collapse
|
9
|
Cao B, Guo HY, Hao XL, Wu ZH, Wu FG, Yu ZW. Transition Mechanism from Nonlamellar to Well-Ordered Lamellar Phases: Is the Lamellar Liquid-Crystal Phase a Must? J Phys Chem Lett 2021; 12:4484-4489. [PMID: 33956459 DOI: 10.1021/acs.jpclett.1c01146] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding the self-assembly mechanisms of amphiphilic molecules in solutions and regulating their phase behaviors are of primary significance for their applications. To challenge the reported direct phase transitions from nonlamellar to ordered lamellar phases, the self-assembly and phase behavior of the 1-hexadecyl-3-methylimidazolium chloride aqueous dispersions were studied using a strategy of isothermal incubation after the temperature jump. A disordered lamellar phase (identified as the lamellar liquid-crystal (Lα) phase), serving as an intermediate, was found to bridge the transition from a spherical micellar (M) phase to a lamellar-gel (Lβ) phase. Meanwhile, the nonsynchronicity in the tail and headgroup regions of the ionic liquid surfactant during the transition process was also unveiled, with the former being prior to the latter. The in-depth understanding of the self-assembly mechanisms may help push forward the related applications in the future.
Collapse
Affiliation(s)
- Bobo Cao
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Hao-Yue Guo
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Xiao-Lei Hao
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Zhong-Hua Wu
- Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fu-Gen Wu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, Jiangsu, P. R. China
| | - Zhi-Wu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| |
Collapse
|
10
|
Milsom A, Squires AM, Woden B, Terrill NJ, Ward AD, Pfrang C. The persistence of a proxy for cooking emissions in megacities: a kinetic study of the ozonolysis of self-assembled films by simultaneous small and wide angle X-ray scattering (SAXS/WAXS) and Raman microscopy. Faraday Discuss 2021; 226:364-381. [PMID: 33284926 DOI: 10.1039/d0fd00088d] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cooking emissions account for a significant proportion of the organic aerosols emitted into the urban environment and high pollution events have been linked to an increased organic content on urban particulate matter surfaces. We present a kinetic study on surface coatings of self-assembled (semi-solid) oleic acid-sodium oleate cooking aerosol proxies undergoing ozonolysis. We found clear film thickness-dependent kinetic behaviour and measured the effect of the organic phase on the kinetics for this system. In addition to the thickness-dependent kinetics, we show that significant fractions of unreacted proxy remain after extensive ozone exposure and that this effect scales approximately linearly with film thickness, suggesting that a late-stage inert reaction product may form and inhibit reaction progress - effectively building up an inert crust. We determine this by using a range of simultaneous analytical techniques; most notably Small-Angle X-ray Scattering (SAXS) has been used for the first time to measure the reaction kinetics of films of a wide range of thicknesses from ca. 0.59 to 73 μm with films <10 μm thick being of potential atmospheric relevance. These observations have implications for the evolution of particulate matter in the urban environment, potentially extending the atmospheric lifetimes of harmful aerosol components and affecting the local urban air quality and climate.
Collapse
Affiliation(s)
- Adam Milsom
- University of Birmingham, School of Geography, Earth and Environmental Sciences, Edgbaston, Birmingham, B15 2TT, UK.
| | | | | | | | | | | |
Collapse
|
11
|
Huang D, Wang J, Xia H, Zhang Y, Bao F, Li M, Chen C, Zhao J. Enhanced Photochemical Volatile Organic Compounds Release from Fatty Acids by Surface-Enriched Fe(III). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:13448-13457. [PMID: 33081467 DOI: 10.1021/acs.est.0c03793] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Both Fe(III) and fatty acids are ubiquitous and important species in environmental waters. Because they are amphipathic, many fatty acids are surface active and prone to enrichment at the air-water interface. Here, we report that by using nonanoic acid (NA) as a model fatty acid, coexisting Fe(III), even at concentrations as low as 1 μM, markedly enhanced the photochemical release of NA-derived volatile organic compounds (VOCs) such as octanal and octane into the air. Further studies indicated that the surface-enriched fatty acids dramatically increase the local concentration of Fe(III) at the water surface, which enables Fe(III)-mediated photochemical reactions to take place at the air-water interface, and the VOCs facilely produced by fatty acid photooxidation can then be released into the air. Moreover, the product distribution in the Fe(III)-mediated reactions was largely different from that in other photochemical systems, and a mechanism based on photochemical decarboxylation is proposed. Considering that the coexistence of fatty acids and Fe(III) in the environment is common, the enhanced photochemical release of VOCs by surface-enriched fatty acids and Fe(III) may be an important channel for the atmospheric emission of VOCs, which are known to play an essential role in the formation of ozone and secondary organic aerosols.
Collapse
Affiliation(s)
- Di Huang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jinzhao Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hongling Xia
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yue Zhang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fengxia Bao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Meng Li
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Chuncheng Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jincai Zhao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| |
Collapse
|
12
|
Night-Time Oxidation of a Monolayer Model for the Air–Water Interface of Marine Aerosols—A Study by Simultaneous Neutron Reflectometry and in Situ Infra-Red Reflection Absorption Spectroscopy (IRRAS). ATMOSPHERE 2018. [DOI: 10.3390/atmos9120471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This paper describes experiments on the ageing of a monolayer model for the air–water interface of marine aerosols composed of a typical glycolipid, galactocerebroside (GCB). Lipopolysaccharides have been observed in marine aerosols, and GCB is used as a proxy for these more complex lipopolysaccharides. GCB monolayers are investigated as pure films, as mixed films with palmitic acid, which is abundant in marine aerosols and forms a stable attractively mixed film with GCB, particularly with divalent salts present in the subphase, and as mixed films with palmitoleic acid, an unsaturated analogue of palmitic acid. Such mixed films are more realistic models of atmospheric aerosols than simpler single-component systems. Neutron reflectometry (NR) has been combined in situ with Fourier transform infra-red reflection absorption spectroscopy (IRRAS) in a pioneering analysis and reaction setup designed by us specifically to study mixed organic monolayers at the air–water interface. The two techniques in combination allow for more sophisticated observation of multi-component monolayers than has previously been possible. The structure at the air–water interface was also investigated by complementary Brewster angle microscopy (BAM). This study looks specifically at the oxidation of the organic films by nitrate radicals (NO3•), the key atmospheric oxidant present at night. We conclude that NO3• oxidation cannot fully remove a cerebroside monolayer from the surface on atmospherically relevant timescales, leaving its saturated tail at the interface. This is true for pure and salt water subphases, as well as for single- and two-component films. The behaviour of the unsaturated tail section of the molecule is more variable and is affected by interactions with co-deposited species. Most surprisingly, we found that the presence of CaCl2 in the subphase extends the lifetime of the unsaturated tail substantially—a new explanation for longer residence times of materials in the atmosphere compared to lifetimes based on laboratory studies of simplified model systems. It is thus likely that aerosols produced from the sea-surface microlayer at night will remain covered in surfactant molecules on atmospherically relevant timescales with impact on the droplet’s surface tension and on the transport of chemical species across the air–water interface.
Collapse
|
13
|
Reid JP, Bertram AK, Topping DO, Laskin A, Martin ST, Petters MD, Pope FD, Rovelli G. The viscosity of atmospherically relevant organic particles. Nat Commun 2018; 9:956. [PMID: 29511168 PMCID: PMC5840428 DOI: 10.1038/s41467-018-03027-z] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/12/2018] [Indexed: 11/13/2022] Open
Abstract
The importance of organic aerosol particles in the environment has been long established, influencing cloud formation and lifetime, absorbing and scattering sunlight, affecting atmospheric composition and impacting on human health. Conventionally, ambient organic particles were considered to exist as liquids. Recent observations in field measurements and studies in the laboratory suggest that they may instead exist as highly viscous semi-solids or amorphous glassy solids under certain conditions, with important implications for atmospheric chemistry, climate and air quality. This review explores our understanding of aerosol particle phase, particularly as identified by measurements of the viscosity of organic particles, and the atmospheric implications of phase state.
Collapse
Affiliation(s)
- Jonathan P Reid
- School of Chemistry, University of Bristol, Manchester, BS8 1TS, UK.
| | - Allan K Bertram
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | - David O Topping
- School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, UK
| | - Alexander Laskin
- Department of Chemistry, Purdue University, West Lafayette, IN, USA
| | - Scot T Martin
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Markus D Petters
- Department of Marine Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, 27695, USA
| | - Francis D Pope
- School of Geography, Earth and Environmental Sciences, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK
| | - Grazia Rovelli
- School of Chemistry, University of Bristol, Manchester, BS8 1TS, UK
| |
Collapse
|
14
|
Varadharajan R, Leermakers FAM. Sign Switch of Gaussian Bending Modulus for Microemulsions: A Self-Consistent Field Analysis Exploring Scale Invariant Curvature Energies. PHYSICAL REVIEW LETTERS 2018; 120:028003. [PMID: 29376681 DOI: 10.1103/physrevlett.120.028003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/14/2017] [Indexed: 06/07/2023]
Abstract
Bending rigidities of tensionless balanced liquid-liquid interfaces as occurring in microemulsions are predicted using self-consistent field theory for molecularly inhomogeneous systems. Considering geometries with scale invariant curvature energies gives unambiguous bending rigidities for systems with fixed chemical potentials: the minimal surface Im3m cubic phase is used to find the Gaussian bending rigidity κ[over ¯], and a torus with Willmore energy W=2π^{2} allows for direct evaluation of the mean bending modulus κ. Consistent with this, the spherical droplet gives access to 2κ+κ[over ¯]. We observe that κ[over ¯] tends to be negative for strong segregation and positive for weak segregation, a finding which is instrumental for understanding phase transitions from a lamellar to a spongelike microemulsion. Invariably, κ remains positive and increases with increasing strength of segregation.
Collapse
Affiliation(s)
- Ramanathan Varadharajan
- Physical Chemistry and Soft Matter, Wageningen University and Research Center, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Frans A M Leermakers
- Physical Chemistry and Soft Matter, Wageningen University and Research Center, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| |
Collapse
|
15
|
Wellen Rudd BA, Vidalis AS, Allen HC. Thermodynamic versus non-equilibrium stability of palmitic acid monolayers in calcium-enriched sea spray aerosol proxy systems. Phys Chem Chem Phys 2018; 20:16320-16332. [DOI: 10.1039/c8cp01188e] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Calcium ions bind to palmitic acid monolayers at the air–aqueous interface resulting in changes of both thermodynamic and non-equilibrium stability.
Collapse
Affiliation(s)
| | - Andrew S. Vidalis
- Department of Chemistry & Biochemistry
- The Ohio State University
- Columbus
- USA
| | - Heather C. Allen
- Department of Chemistry & Biochemistry
- The Ohio State University
- Columbus
- USA
| |
Collapse
|