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Ling J, Zheng S, Sheng F, Wu H, Chen Z, Gu C, Jin X. Effect of common inorganic anions on iron-catalyzed secondary brown carbon formation from guaiacol. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 770:145206. [PMID: 33736418 DOI: 10.1016/j.scitotenv.2021.145206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Brown carbon (BrC) is the important component of aerosol with strong UV-visible absorbance. However, the formation of BrC is still elusive. Inorganic anions, e.g., Cl-, NO3- and SO42-, exist ubiquitously in the atmosphere, while their effects on the formation of BrC are poorly understood. In this study, we have systematically investigated the effects of pH (1, 2 and 3), inorganic anion (Cl-, NO3- and SO42-) and ionic strength (0.1, 0.5 and 1.0 M) on BrC generation process by measuring the optical, aggregation and product properties. Our results clearly show that the three factors strongly affect the BrC formation by influencing the oxidation activity and the complexation capability of different Fe(III) species. Marcus theory was used in this research to calculate the oxidation activity of different Fe(III) species. Among all the species of Fe(III), FeOH2+ is the most reactive form in the BrC formation reaction. Furthermore, the aggregation process of BrC was also studied, which is affected by different anions due to their different concentration and hydrability, and SO42- exhibits the highest efficiency to induce the aggregation of BrC. This study will deepen our understanding about the natural formation of BrC under environmentally relevant conditions, and be beneficial for controlling the production of atmospheric particulates and the subsequent health effects.
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Affiliation(s)
- Jingyi Ling
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Siheng Zheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Feng Sheng
- State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, PR China
| | - Hao Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Zhanghao Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Xin Jin
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
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Al-Abadleh HA, Rana MS, Mohammed W, Guzman MI. Dark Iron-Catalyzed Reactions in Acidic and Viscous Aerosol Systems Efficiently Form Secondary Brown Carbon. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:209-219. [PMID: 33290060 DOI: 10.1021/acs.est.0c05678] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Iron-driven secondary brown carbon formation reactions from water-soluble organics in cloud droplets and aerosols create insoluble and soluble products of emerging atmospheric importance. This work shows, for the first time, results on dark iron-catalyzed polymerization of catechol forming insoluble black polycatechol particles and colored water-soluble oligomers under conditions characteristic of viscous multicomponent aerosol systems with relatively high ionic strength (I = 1-12 m) and acidic pH (∼2). These systems contain ammonium sulfate (AS)/nitrate (AN) and C3-C5 dicarboxylic acids, namely, malonic, malic, succinic, and glutaric acids. Using dynamic light scattering (DLS) and ultra high pressure liquid chromatography-mass spectrometry (UHPLC-MS), we show results on the rate of particle growth/agglomeration and identity of soluble oligomeric reaction products. We found that increasing I above 1 m and adding diacids with oxygen-to-carbon molar ratio (O:C > 1) significantly reduced the rate of polycatechol formation/aggregation by a factor of 1.3 ± 0.4 in AS solution in the first 60 min of reaction time. Using AN, rates were too slow to be quantified using DLS, but particles formed after 24 h reaction time. These results were explained by the relative concentration and affinity of ligands to Fe(III). We also report detectable amounts of soluble and colored oligomers in reactions with a slow rate of polycatechol formation, including organonitrogen compounds. These results highlight that brown carbon formation from iron chemistry is efficient under a wide range of aerosol physical states and chemical composition.
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Affiliation(s)
- Hind A Al-Abadleh
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Md Sohel Rana
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Wisam Mohammed
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada
| | - Marcelo I Guzman
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
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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.
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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
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Yang C, Zhang C, Luo X, Liu X, Cao F, Zhang YL. Isomerization and Degradation of Levoglucosan via the Photo-Fenton Process: Insights from Aqueous-Phase Experiments and Atmospheric Particulate Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11789-11797. [PMID: 32897062 DOI: 10.1021/acs.est.0c02499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
So far, studies on the conversion of stereochemistry under photo-Fenton conditions and their atmospheric implication are still rare. Here, we found that the biomass burning marker, the chiral compound levoglucosan (L), undergoes oxidative degradation under photo-Fenton conditions and can be isomerized into mannosan (M) and galactosan (G) simultaneously. Among the formic acid, acetic acid, and oxalic acid in the degradation products of levoglucosan, it was found that the yield of formation of formic acid in the photo-Fenton pathway can be as high as 86%. It is worth noting that both levoglucosan and its isomers are present in the atmosphere and their concentrations are strongly correlated. At the same time, the range of their concentration ratios, L/(G + M), measured in the photo-Fenton experiments in the laboratory was found to agree well with that measured in atmospheric PM2.5 samples. However, the sources of L, G, and M in the atmosphere are complex, and the photo-Fenton reaction may be an essential pathway for the distribution of L, G, and M in the atmosphere.
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Affiliation(s)
- Chi Yang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Chunyan Zhang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xiaosan Luo
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xiaoyan Liu
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Fang Cao
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Yan-Lin Zhang
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
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Zhu Z, Zhang J, Lv G, George C, Herrmann H, Fu H, Li D, Zhang L, Sun X, Sun H, Guan X, Li Q, Dong W, Li X, Wang X, Wang L, Yang X, Liu Q, Chen J, Jiang G. Complexation of Fe(III)/Catechols in atmospheric aqueous phase and the consequent cytotoxicity assessment in human bronchial epithelial cells (BEAS-2B). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110898. [PMID: 32652344 DOI: 10.1016/j.ecoenv.2020.110898] [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: 04/30/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
Recent research has shown that the complexation of metals-organics plays an important role in atmospheric particulate matter, whose health effects should be taken into account. This work investigates the interactions between catechols (CAs), i.e., 4-nitrocatechol (4NC) and 4-methylcatechol (4MC), and transition metals (i.e., Fe) in the aqueous phase dark reaction. The formation of Fe/CAs complexes and secondary organics products are analyzed by UV-Vis spectroscopy, stopped-flow spectroscopy, high-resolution mass spectrometry and Raman spectroscopy, while the insoluble particulate matter formed from the CAs/Fe mixtures are characterized by the FTIR, X-ray photoelectron spectroscopy (XPS) and thermogravimetric-quadrupole-mass spectrometry (TG-Q-MS). On the basis of the density functional theory (DFT) calculation and experimental results, the possible formation pathways for the complexes of Fe(III) with 4NC (a proxy for organics) are proposed. The Fe/CAs complexes and organics products perhaps have significant sources of light absorption which play an important role in influencing the intensity of atmospheric radiation and particulate phase photochemistry. Besides, the cytotoxicity is tested as a function of concentrations for CAs/Fe mixtures in BEAS-2B cells. Our results show that CAs/Fe mixtures have strong association with cytotoxicity, indicating the mixtures have potential influence to human health.
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Affiliation(s)
- Zhonghong Zhu
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Jin Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Guochun Lv
- Environment Research Institute, Shandong University, Jinan, 250100, China
| | - Christian George
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China; University of Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France; School of Environmental Science & Engineering, Shandong University, Jinan, 250100, China
| | - Hartmut Herrmann
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China; Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department, Permoserstr. 15, D-04318, Leipzig, Germany; School of Environmental Science & Engineering, Shandong University, Jinan, 250100, China
| | - Hongbo Fu
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Dan Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Liwu Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Xiaomin Sun
- Environment Research Institute, Shandong University, Jinan, 250100, China
| | - Hao Sun
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Xiaohong Guan
- School of Environmental Science & Engineering, Tongji University, Shanghai, 200433, China
| | - Qing Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Wenbo Dong
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Xiang Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Xinke Wang
- University of Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France
| | - Lin Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Xin Yang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China
| | - Qian Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Jianmin Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200438, China; Institute of Eco-Chongming (IEC), 3663 N. Zhongshan Rd., Shanghai, 200062, China.
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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Jiang SY, Gali NK, Ruan HD, Ning Z. Photo-oxidation of particle phase iron species dominates the generation of reactive oxygen species in secondary aerosol. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 723:137994. [PMID: 32224395 DOI: 10.1016/j.scitotenv.2020.137994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/15/2020] [Accepted: 03/15/2020] [Indexed: 06/10/2023]
Abstract
This study presents an experimental investigation on the photochemical transformation of iron species in aerosol including dissolution of insoluble iron species into soluble fraction, and soluble ferric oxidation to ferrous form. This process has significantly contributed to the aerosol oxidative potential in generation of reactive oxygen species (ROS). We conducted both laboratory experiment of UV irradiation and real world solar irradiation on large variation of aerosol samples for the characterization of iron speciation in insoluble and soluble fractions to investigate their transformation under photooxidation process. The results showed that the real world solar irradiation significantly increased the soluble Fe(II) fraction, and this is corroborated by laboratory simulation of UV irradiation showing increasing soluble Fe(II) fraction with elongating aging time. The results further exhibited that the dissolution of iron component into soluble fraction was a dominant process, followed by the conversion of soluble ferric to ferrous ions. Further, the study confirmed that the oxidative potential of particulate matter (PM) is attributed dominantly to the abundance of transition metals, i.e. Fe, and the incremental ROS generation after photochemical process is attributed largely to the transformation of solid phase iron species to soluble Fe(II). The results suggest that transition metals, for example by iron in this study, play an important role in secondary aerosol process.
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Affiliation(s)
- Sabrina Yanan Jiang
- Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong; Division of Science and Technology, Beijing Normal University-Hong Kong Baptist University United International College, China
| | - Nirmal Kumar Gali
- Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong
| | - Huada Daniel Ruan
- Division of Science and Technology, Beijing Normal University-Hong Kong Baptist University United International College, China
| | - Zhi Ning
- Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong.
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Al Nimer A, Rocha L, Rahman MA, Nizkorodov SA, Al-Abadleh HA. Effect of Oxalate and Sulfate on Iron-Catalyzed Secondary Brown Carbon Formation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6708-6717. [PMID: 31034222 DOI: 10.1021/acs.est.9b00237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Oxalate and sulfate are ubiquitous components of ambient aerosols with a high complexation affinity to iron. However, their effect on iron-driven secondary brown carbon formation in solution from soluble aromatic and aliphatic reagents was not studied. We report masses and hydrodynamic particle sizes of insoluble particles formed from the dark aqueous phase reaction of catechol, guaiacol, fumaric, and muconic acids with Fe(III) in the presence of oxalate or sulfate. Results show that oxalate decreases particle yield in solution from the reaction of Fe(III), with a stronger effect for guaiacol than catechol. For both compounds, the addition of sulfate results in the formation of more polydisperse (0.1-5 μm) and heavier particles than those from control experiments. Reactions with fumaric and muconic acids show that oxalate (not sulfate) and pH are determining factors in the efficiency of particle formation in solution. Polymerization reactions occur readily in the presence of sulfate in solution producing particles with iron-coordinated and/or pore-trapped sulfate anions. The addition of oxalate to the reactions of Fe(III) with all organics, except guaiacol, produced fewer and larger polymeric particles (>0.5 μm). These results imply that even in the presence of competing ligands, the formation of insoluble and colored particles from soluble organic precursors still dominates over the formation of soluble iron complexes.
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Affiliation(s)
- Aseel Al Nimer
- Department of Chemistry and Biochemistry , Wilfrid Laurier University , Waterloo , ON N2L 3C5 , Canada
| | - Laura Rocha
- Department of Chemistry and Biochemistry , Wilfrid Laurier University , Waterloo , ON N2L 3C5 , Canada
| | - Mohammad A Rahman
- Department of Chemistry and Biochemistry , Wilfrid Laurier University , Waterloo , ON N2L 3C5 , Canada
| | - Sergey A Nizkorodov
- Department of Chemistry , University of California , Irvine , CA 92697 , United States
| | - Hind A Al-Abadleh
- Department of Chemistry and Biochemistry , Wilfrid Laurier University , Waterloo , ON N2L 3C5 , Canada
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Rahman M, Al-Abadleh HA. Surface Water Structure and Hygroscopic Properties of Light Absorbing Secondary Organic Polymers of Atmospheric Relevance. ACS OMEGA 2018; 3:15519-15529. [PMID: 31458208 PMCID: PMC6644084 DOI: 10.1021/acsomega.8b02066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/01/2018] [Indexed: 06/09/2023]
Abstract
Hygroscopic properties and chemical reactivity of secondary organic aerosols (SOA) influence their overall contribution to the indirect effect on the climate. In this study, we investigate the hygroscopic properties of organic and organometallic polymeric particles, namely polycatechol, polyguaiacol, Fe-polyfumarte, and Fe-polymuconate. These particles efficiently form in iron-catalyzed reactions with aromatic and aliphatic dicarboxylic acid compounds detected in field-collected SOA. The structure of surface water was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and the uptake of gas water was quantified using quartz crystal microbalance (QCM) as a function of relative humidity. Spectroscopic data show that water bonding with organic functional groups acting as hydrogen bond acceptors causes shifts in their vibrational modes. Analysis of the hydroxyl group stretching region revealed weak and strong hydrogen bonding networks that suggest cluster formation reflecting water-water and water-organics interactions, respectively. A modified Type II multilayer Brunauer-Emmett-Teller adsorption model described the adsorption isotherm on the nonporous materials, polycatechol, polyguaiacol, and Fe-polymuconate. However, water adsorption on porous Fe-polyfumarate was best described using a Type V adsorption model, namely the Langmuir-Sips model that accounts for condensation in pores. The data revealed that organometallic polymers are more hygroscopic than organic polymers. The implications of these investigations are discussed in the context of the chemical reactivity of these particles relative to known SOA.
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