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Yoo H, Seo D, Shin D, Ro CU. Direct Observation of Particle-To-Particle Variability in Ambient Aerosol pH Using a Novel Analytical Approach Based on Surface-Enhanced Raman Spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:7977-7985. [PMID: 38664901 DOI: 10.1021/acs.est.4c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
The pH of atmospheric aerosols is a key characteristic that profoundly influences their impacts on climate change, human health, and ecosystems. Despite widely performed aerosol pH research, determining the pH levels of individual atmospheric aerosol particles has been a challenge. This study presents a novel analytical technique that utilizes surface-enhanced Raman spectroscopy to assess the pH of individual ambient PM2.5-10 aerosol particles in conjunction with examining their hygroscopic behavior, morphology, and elemental compositions. The results revealed a substantial pH variation among simultaneously collected aerosol particles, ranging from 3.3 to 5.7. This variability is likely related to each particle's unique reaction and aging states. The extensive particle-to-particle pH variability suggests that atmospheric aerosols present at the same time and location can exhibit diverse reactivities, reaction pathways, phase equilibria, and phase separation properties. This pioneering study paves the way for in-depth investigations into particle-to-particle variability, size dependency, and detailed spatial and temporal variations of aerosol pH, thus deepening our understanding of atmospheric chemistry and its environmental implications.
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Affiliation(s)
- Hanjin Yoo
- Department of Chemistry, Inha University, Incheon 22212, Republic of Korea
- Particle Pollution Management Center, Inha University, Incheon 21999, Republic of Korea
| | - Dongkwon Seo
- Department of Chemistry, Inha University, Incheon 22212, Republic of Korea
| | - Dongha Shin
- Department of Chemistry, Inha University, Incheon 22212, Republic of Korea
| | - Chul-Un Ro
- Department of Chemistry, Inha University, Incheon 22212, Republic of Korea
- Particle Pollution Management Center, Inha University, Incheon 21999, Republic of Korea
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2
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Ye Q, Yao M, Wang W, Li Z, Li C, Wang S, Xiao H, Zhao Y. Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168736. [PMID: 37996034 DOI: 10.1016/j.scitotenv.2023.168736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 11/06/2023] [Accepted: 11/19/2023] [Indexed: 11/25/2023]
Abstract
There is growing evidence that the interactions between sulfur dioxide (SO2) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO2 remains unknown. In this study, we investigate the multiphase reactions of SO2 with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO2 on toluene SOA was determined to be on the order of 10-4, depending strikingly on aerosol water content. POs contribute significantly to the multiphase reactivity of toluene SOA, but they can only explain a portion of the measured SO2 uptake, suggesting the presence of other reactive species in SOA that also contribute to the particle reactivity toward SO2. The second-order reaction rate constant (kII) between S(IV) and toluene-derived POs was estimated to be in the range of the kII values previously reported for commercially available POs (e.g., 2-butanone peroxide and 2-tert-butyl hydroperoxide) and the smallest (C1-C2) and biogenic POs. In addition, unlike commercial POs that can efficiently convert S(IV) into both inorganic sulfate and organosulfates, toluene-derived POs appear to mainly oxidize S(IV) to inorganic sulfate. Our study reveals the multiphase reactivity of typical anthropogenic SOA and POs toward SO2 and will help to develop a better understanding of the formation and evolution of atmospheric secondary aerosol.
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Affiliation(s)
- Qing Ye
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Min Yao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Environmental & Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
| | - Wei Wang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ziyue Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chenxi Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shunyao Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Huayun Xiao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yue Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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3
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Wallace BJ, Mongeau ML, Zuend A, Preston TC. Impact of pH on Gas-Particle Partitioning of Semi-Volatile Organics in Multicomponent Aerosol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16974-16988. [PMID: 37885068 DOI: 10.1021/acs.est.3c02894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The partitioning of semivolatile organic compounds (SVOCs) between the condensed and gas phases can have significant implications for the properties of aerosol particles. In addition to affecting size and composition, this partitioning can alter radiative properties and impact cloud activation processes. We present measurements and model predictions on how activity and pH influence the evaporation of SVOCs from particles to the gas phase, specifically investigating aqueous inorganic particles containing dicarboxylic acids (DCAs). The aerosols are studied at the single-particle level by using optical trapping and cavity-enhanced Raman spectroscopy. Optical resonances in the spectra enable precise size tracking, while vibrational bands allow real-time monitoring of pH. Results are compared to a Maxwell-type model that accounts for volatile and nonvolatile solutes in aqueous droplets that are held at a constant relative humidity. The aerosol inorganic-organic mixture functional group activity coefficients thermodynamic model and Debye-Hückel theory are both used to calculate the activities of the species present in the droplet. For DCAs, we find that the evaporation rate is highly sensitive to the particle pH. For acidity changes of approximately 1.5 pH units, we observe a shift from a volatile system to one that is completely nonvolatile. We also observe that the pH itself is not constant during evaporation; it increases as DCAs evaporate, slowing the rate of evaporation until it eventually ceases. Whether a DCA evaporates or remains a stable component of the droplet is determined by the difference between the lowest pKa of the DCA and the pH of the droplet.
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Affiliation(s)
- Brandon J Wallace
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Michel Laforest Mongeau
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Andreas Zuend
- Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0B9
| | - Thomas C Preston
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
- Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0B9
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4
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Tong YK, Ye A. Liquid-Liquid Phase Separation in Single Suspended Aerosol Microdroplets. Anal Chem 2023; 95:12200-12208. [PMID: 37556845 DOI: 10.1021/acs.analchem.2c05605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Liquid-liquid phase separation (LLPS) is ubiquitous in ambient aerosols. This specific morphology exerts substantial impacts on the physicochemical properties and atmospheric processes of aerosols, particularly on the gas-particle mass transfer, the interfacial heterogeneous reaction, and the surface albedo. Although there are many studies on the LLPS of aerosols, a clear picture of LLPS in individual aerosols is scarce due to the experimental difficulties of trapping a single particle and mimicking the suspended state of real aerosols. Here, we investigate the phase separation in individual contactless microdroplets by a self-constructed laser tweezer/Raman spectroscopy system. The dynamic transformation of the morphology of optically trapped droplets over the course of humidity cycles is detected by the time-resolved cavity-enhanced Raman spectra. The impacts of pH and inorganic components on LLPS in aerosols are discussed. The results show that the increasing acidity can enhance the miscibility between the hydrophilic and hydrophobic phases and decrease the separation relative humidity of aerosols. Moreover, the inorganic components also have various impacts on the aerosol phase state, whose influence depends on their different salting-out capabilities. It brings possible implications on the morphology of actual atmospheric particles, particularly for those dominated by internal mixtures of inorganic and organic components.
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Affiliation(s)
- Yu-Kai Tong
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China
| | - Anpei Ye
- Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China
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5
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Angle KJ, Grassian VH. Direct quantification of changes in pH within single levitated microdroplets and the kinetics of nitrate and chloride depletion. Chem Sci 2023; 14:6259-6268. [PMID: 37325137 PMCID: PMC10266444 DOI: 10.1039/d2sc06994f] [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: 12/21/2022] [Accepted: 04/11/2023] [Indexed: 06/17/2023] Open
Abstract
The hygroscopicity and pH of aqueous microdroplets and smaller aerosols control their impacts on human health and the climate. Nitrate depletion and chloride depletion through the partitioning of HNO3 and HCl into the gas phase are processes that are enhanced in micron-sized and smaller aqueous droplets and this depletion influences both hygroscopicity and pH. Despite a number of studies, uncertainties remain about these processes. While acid evaporation and the loss of HCl or HNO3 have been observed during dehydration, there is a question as to the rate of acid evaporation and whether this can occur in fully hydrated droplets at higher relative humidity (RH). To directly elucidate the kinetics of nitrate and chloride depletion through evaporation of HNO3 and HCl, respectively at high RH, single levitated microdroplets are probed with cavity-enhanced Raman spectroscopy. Using glycine as a novel in situ pH probe, we are able to simultaneously measure changes in microdroplet composition and pH over timescales of hours. We find that the loss of chloride from the microdroplet is faster than that of nitrate, and the calculated rate constants infer that depletion is limited by the formation of HCl or HNO3 at the air-water interface and subsequent partitioning into the gas phase.
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Affiliation(s)
- Kyle J Angle
- Department of Chemistry and Biochemistry, University of California San Diego La Jolla CA 92093 USA
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry, University of California San Diego La Jolla CA 92093 USA
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6
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Li M, Kan Y, Su H, Pöschl U, Parekh SH, Bonn M, Cheng Y. Spatial homogeneity of pH in aerosol microdroplets. Chem 2023. [DOI: 10.1016/j.chempr.2023.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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7
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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.
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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.
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8
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Jing X, Chen Z, Huang Q, Liu P, Zhang YH. Spatiotemporally Resolved pH Measurement in Aerosol Microdroplets Undergoing Chloride Depletion: An Application of In Situ Raman Microspectrometry. Anal Chem 2022; 94:15132-15138. [PMID: 36251492 DOI: 10.1021/acs.analchem.2c03381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acidity is a defining property of atmospheric aerosols that profoundly affects environmental systems, human health, and climate. However, directly measuring the pH of aerosol microdroplets remains a challenge, especially when the microdroplets' composition is nonhomogeneous or dynamically evolving or both. As a result, a pH measurement technique with high spatiotemporal resolution is needed. Here, we report a spatiotemporally resolved pH measurement technique in microdroplets using spontaneous Raman spectroscopy. Our target sample was the microdroplets comprising sodium chloride and oxalic acid─laboratory surrogates of sea spray aerosols and water-soluble organic compounds, respectively. Our measurements show that the chloride depletion from the microdroplets caused a continuous increase in pH by ∼0.5 units in 2 hours. Meanwhile, the surface propensity of chloride anions triggers a stable pH gradient inside a single droplet, with the pH at the droplet surface lower than that at the core by ∼ 0.4 units. The uncertainties arising from the Raman detection limit (±0.08 pH units) and from the nonideal solution conditions (-0.06 pH units) are constrained. Our findings indicate that spontaneous Raman spectroscopy is a simple yet robust technique for precise pH measurement in aerosols with high spatiotemporal resolution.
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Affiliation(s)
- Xinbo Jing
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing100081, China
| | - Zhe Chen
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing100081, China
| | - Qishen Huang
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing100081, China.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania16801, United States
| | - Pai Liu
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing100081, China
| | - Yun-Hong Zhang
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing100081, China
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9
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Li M, Su H, Zheng G, Kuhn U, Kim N, Li G, Ma N, Pöschl U, Cheng Y. Aerosol pH and Ion Activities of HSO 4- and SO 42- in Supersaturated Single Droplets. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12863-12872. [PMID: 36047919 PMCID: PMC9494740 DOI: 10.1021/acs.est.2c01378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 08/23/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Accurate determination of acidity (pH) and ion activities in aqueous droplets is a major experimental and theoretical challenge for understanding and simulating atmospheric multiphase chemistry. Here, we develop a ratiometric Raman spectroscopy method to measure the equilibrium concentration of sulfate (SO42-) and bisulfate (HSO4-) in single microdroplets levitated by aerosol optical tweezers. This approach enables determination of ion activities and pH in aqueous sodium bisulfate droplets under highly supersaturated conditions. The experimental results were compared against aerosol thermodynamic model calculations in terms of simulating aerosol ion concentrations, ion activity coefficients, and pH. We found that the Extended Aerosol Inorganics Model (E-AIM) can well reproduce the experimental results. The alternative model ISORROPIA, however, exhibits substantial deviations in SO42- and HSO4- concentrations and up to a full unit of aerosol pH under acidic conditions, mainly due to discrepancies in simulating ion activity coefficients of SO42--HSO4- equilibrium. Globally, this may cause an average deviation of ISORROPIA from E-AIM by 25 and 65% in predicting SO42- and HSO4- concentrations, respectively. Our results show that it is important to determine aerosol pH and ion activities in the investigation of sulfate formation and related aqueous phase chemistry.
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Affiliation(s)
- Meng Li
- Minerva
Research Group, Max Planck Institute for
Chemistry, 55128 Mainz, Germany
| | - Hang Su
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, 55128 Mainz, Germany
| | - Guangjie Zheng
- Minerva
Research Group, Max Planck Institute for
Chemistry, 55128 Mainz, Germany
| | - Uwe Kuhn
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, 55128 Mainz, Germany
| | - Najin Kim
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, 55128 Mainz, Germany
| | - Guo Li
- Minerva
Research Group, Max Planck Institute for
Chemistry, 55128 Mainz, Germany
| | - Nan Ma
- Minerva
Research Group, Max Planck Institute for
Chemistry, 55128 Mainz, Germany
- Institute
for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
| | - Ulrich Pöschl
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, 55128 Mainz, Germany
| | - Yafang Cheng
- Minerva
Research Group, Max Planck Institute for
Chemistry, 55128 Mainz, Germany
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10
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Qin J, Zhang L, Qin Y, Shi S, Li J, Gao Y, Tan J, Wang X. pH-Dependent Chemical Transformations of Humic-Like Substances and Further Cognitions Revealed by Optical Methods. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:7578-7587. [PMID: 35650515 DOI: 10.1021/acs.est.1c07729] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Humic-like substances (HULIS) are macromolecular complex groups in water-soluble organic compounds (WSOC). pH is a crucial factor that influences the chemical transformations of HULIS in atmospheric particles, but this has been rarely investigated, especially under varying pH conditions. This study attempted to unveil the chemical transformation mechanisms of HULIS under a range of pH conditions using optical methods. The pH-dependent light absorption and fluorescence properties of HULIS were comprehensively analyzed; the acidity coefficient (pKa) of HULIS in relation to chemical structures was determined, and the hypothetical chemical transformation mechanisms of HULIS with increasing pH were analyzed by optical characterizations. The results suggested that pH greatly impacted the light absorption and fluorescence efficiencies of HULIS in both winter and summer seasons, and pKa was an important inflection point. The pKa of HULIS ranged from 3.5 to 8.0 in winter and 6.4 to 10.0 in summer. The acidic/basic groups were identified as -OH or -NH2 substituted quinolines, carboxylic aromatics, and pyridines. The pH-sensitive species accounted for about 6% and 21% of HULIS-C (carbon concentrations of HULIS) in winter and summer, respectively. The varying optical spectra with increasing pH might result from charge transfer or complex reactions with HULIS deprotonation.
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Affiliation(s)
- Juanjuan Qin
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Leiming Zhang
- Air Quality Research Division, Science & Technology Branch, Environment and Climate Change Canada, Toronto M3H5T4, Canada
| | - Yuanyuan Qin
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shaoxuan Shi
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingnan Li
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuwei Gao
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jihua Tan
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinming Wang
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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11
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Li LF, Chen Z, Liu P, Zhang YH. Direct Measurement of pH Evolution in Aerosol Microdroplets Undergoing Ammonium Depletion: A Surface-Enhanced Raman Spectroscopy Approach. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:6274-6281. [PMID: 35476405 DOI: 10.1021/acs.est.1c08626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Accurately measuring the pH of atmospheric aerosols is a prerequisite for understanding the multiphase chemistry that profoundly affects the environment and climate systems. Despite the advancements of experimental techniques for in situ pH measurements in aerosols, current studies are limited to measuring the static pH of aerosol microdroplets with an unperturbed composition. This steady-state scenario, however, deviates from the real-world aerosols undergoing atmospheric aging reactions, specifically, those characterized with a spontaneous displacement of strong bases (or acids) with high volatility. Here, we introduce a continuous and in situ measurement of aerosol pH by using a 4-mercaptopyridine-functionalized silver nanoparticle probe and surface-enhanced Raman spectroscopy. We find that the ammonium depletion─a spontaneous displacement of ammonium by dicarboxylic acid salts─continuously acidifies aerosol water over time. The decaying trends of pH in the aerosols under various humidity conditions can be unified with a universal exponential function. Such an exponentially decaying function further indicates that the ammonium depletion reaction is a self-limiting process. Our technique can be applied to study the dynamic change of aerosol acidity during the complex atmospheric aging processes, toward elucidating their implications on atmospheric chloride, nitrate, and ammonium cycles.
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Affiliation(s)
- Lin-Fang Li
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Zhe Chen
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Pai Liu
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yun-Hong Zhang
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
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12
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Marina-Montes C, Pérez-Arribas LV, Anzano J, de Vallejuelo SFO, Aramendia J, Gómez-Nubla L, de Diego A, Manuel Madariaga J, Cáceres JO. Characterization of atmospheric aerosols in the Antarctic region using Raman Spectroscopy and Scanning Electron Microscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 266:120452. [PMID: 34624816 DOI: 10.1016/j.saa.2021.120452] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/16/2021] [Accepted: 09/26/2021] [Indexed: 06/13/2023]
Abstract
The non-destructive spectroscopic characterization of airborne particulate matter (PM) was performed to gain better knowledge of the internal structures of atmospheric aerosols at the particle level in the Antarctic region, along with their potential sources. PM and soil samples were collected during the 2016-2017 austral summer season at the surroundings of the Spanish Antarctic Research Station "Gabriel de Castilla" (Deception Island, South Shetland Islands). PM was deposited in a low-volume sampler air filter. Raman spectroscopy (RS) and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS) were used to determine the elemental and molecular composition of the individual aerosol and soil particles. Filter spectra measured by these techniques revealed long-range atmospheric transport of organic compounds (polystyrene and bacteria), local single and cluster particles made of different kinds of black carbon (BC), exotic minerals (polyhalite, arcanite, niter, ammonium nitrate, syngenite and nitrogen, phosphorus, and potassium (NPK) fertilizer), and natural PM (sea salts, silicates, iron oxides, etc.). In addition to the filter samples, forsterite and plagioclase were discovered in the soil samples together with magnetite. This is the first report of the presence of a microplastic fiber in the Antarctic air. This fact, together with the presence of other pollutants, reflects that even pristine and remote regions are influenced by anthropogenic activities.
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Affiliation(s)
- César Marina-Montes
- Laser Lab, Chemistry & Environment Group, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Luis V Pérez-Arribas
- Laser Chemistry Research Group, Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain
| | - Jesús Anzano
- Laser Lab, Chemistry & Environment Group, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Silvia Fdez-Ortiz de Vallejuelo
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Julene Aramendia
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Leticia Gómez-Nubla
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Alberto de Diego
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Juan Manuel Madariaga
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Jorge O Cáceres
- Laser Chemistry Research Group, Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Plaza de Ciencias 1, 28040 Madrid, Spain.
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13
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Barquilla MDP, Mayes ML. Role of hydrogen bonding in bulk aqueous phase decomposition, complexation, and covalent hydration of pyruvic acid. Phys Chem Chem Phys 2022; 24:25151-25170. [DOI: 10.1039/d2cp03579k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The behavior of hydrogen bonding changes between the gas and aqueous phase, altering the mechanisms of various pyruvic acid processes and consequently affecting the aerosol formation in different environments.
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Affiliation(s)
- Michael Dave P. Barquilla
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA 02747, USA
| | - Maricris L. Mayes
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA 02747, USA
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14
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Cui X, Tang M, Wang M, Zhu T. Water as a probe for pH measurement in individual particles using micro-Raman spectroscopy. Anal Chim Acta 2021; 1186:339089. [PMID: 34756261 DOI: 10.1016/j.aca.2021.339089] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 09/16/2021] [Accepted: 09/20/2021] [Indexed: 10/20/2022]
Abstract
Atmospheric aerosol acidity impacts numerous physicochemical processes, but the determination of particle pH remains a significant challenge due to the nonconservative nature of the H+ concentration ([H+]). Traditional measurements have difficulty in describing the practical state of an aerosol because they comprise chemical components or hypotheses that change the nature of the particles. In this work, we present a direct pH measurement that uses water as a general probe to detect [H+] in individual particles by micro-Raman spectroscopy. Containing the vibrational bands of ions and water influenced by ions, the spectra of hydrated ion were decomposed from the solution spectra as standard spectra by multivariate curve resolution analysis. Meanwhile, ratios of hydrated ions were calculated between the Raman spectra and standard spectra to evaluate concentration profiles of each ion. It demonstrated that good quantitative models between the ratio and concentration for all ions including H+ can be built with correlation coefficients (R2) higher than 0.95 for the solutions. The method was further applied to individual particle pH measurement. The pH value of sulfate aerosol particles was calculated, and the standard error was 0.09 using pH values calculated from the [HSO4-]/[SO42-] as a reference. Furthermore, the applicability of the method was proven by detecting the pH value of chloride particles. Therefore, utilizing water, the most common substance, as the spectroscopic probe to measure [H+] without restriction of the ion system, this method has potential to measure the pH value of atmospheric particles with various compounds, although more work needs to be done to improve the sensitivity of the method.
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Affiliation(s)
- Xiaoyu Cui
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
| | - Mingjin Tang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China
| | - Mingjin Wang
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
| | - Tong Zhu
- BIC-ESAT and SKL-ESPC, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
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15
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Gong C, Zhao Y, Zhang D, Wang J, Mu C, Wang W, Zhu S, Zhang X. Investigation of the Acid-Mediated Photosensitized Reactions of Amphiphilic α-Keto Acids at the Air-Water Interface Using Field-Induced Droplet Ionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2306-2312. [PMID: 33561341 DOI: 10.1021/jasms.1c00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The photochemistry of α-keto acids has been of great interest due to its implications in atmospheric and prebiotic chemistries. α-Keto acids with long alkyl chains are amphiphilic in nature, and they tend to partition at the air-water interface of atmospheric water droplets and add to the complexity of the chemistries therein. The air-water interface is a unique environment that plays a vital role in overall atmospheric processes. However, existing studies mostly focus on the photochemistry of α-keto acids in the bulk solution and neglect the reactions that occur at the interface. In this study, using the field-induced droplet ionization mass spectrometry methodology that is capable of selectively sampling amphiphilic molecules that reside at the air-water interface, we show that the acid-mediated photochemistry of 2-oxooctanoic acid and 2-oxoheptoic acid is highly different from those of previously reported reactions in the bulk and contributes to the formation of humic-like substances (HULIS). This work emphasizes the uniqueness of the photochemistry at the air-water interface. We anticipate that studies of atmosphere-relevant photochemistry at the air-water interface will be an avenue rich with opportunities.
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Affiliation(s)
- Chu Gong
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Yutao Zhao
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Dongmei Zhang
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Jie Wang
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Chaonan Mu
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Wei Wang
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Shoufei Zhu
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
| | - Xinxing Zhang
- College of Chemistry, Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory and Institute of Elemento-Organic Chemistry, Renewable Energy Conversion and Storage Center (ReCAST), Nankai University, Tianjin 300071, China
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16
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Chang YP, Devi Y, Chen CH. Micro-droplet Trapping and Manipulation: Understanding Aerosol Better for a Healthier Environment. Chem Asian J 2021; 16:1644-1660. [PMID: 33999498 DOI: 10.1002/asia.202100516] [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: 05/13/2021] [Indexed: 11/09/2022]
Abstract
Understanding the physicochemical properties and heterogeneous processes of aerosols is key not only to elucidate the impacts of aerosols on the atmosphere and humans but also to exploit their further applications, especially for a healthier environment. Experiments that allow for spatially control of single aerosol particles and investigations on the fundamental properties and heterogeneous chemistry at the single-particle level have flourished during the last few decades, and significant breakthroughs in recent years promise better control and novel applications aimed at resolving key issues in aerosol science. Here we propose graphene oxide (GO) aerosols as prototype aerosols containing polycyclic aromatic hydrocarbons, and GO can behave as two-dimensional surfactants which could modify the interfacial properties of aerosols. We describe the techniques of trapping single particles and furthermore the current status of the optical spectroscopy and chemistry of GO. The current applications of these single-particle trapping techniques are summarized and interesting future applications of GO aerosols are discussed.
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Affiliation(s)
- Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Yanita Devi
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Chun-Hu Chen
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
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17
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Herboth R, Gopakumar G, Caleman C, Wohlert M. Charge State Dependence of Amino Acid Propensity at Water Surface: Mechanisms Elucidated by Molecular Dynamics Simulations. J Phys Chem A 2021; 125:4705-4714. [PMID: 34042438 PMCID: PMC8279654 DOI: 10.1021/acs.jpca.0c10963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 04/19/2021] [Indexed: 11/28/2022]
Abstract
Atmospheric aerosols contain a variety of compounds, among them free amino acids and salt ions. The pH of the aerosol droplets depends on their origin and environment. Consequently, compounds like free amino acids found in the droplets will be at different charge states, since these states to a great extent depend on the surrounding pH condition. In droplets of marine origin, amino acids are believed to drive salt ions to the water surface and a pH-dependent amino acid surface propensity will, therefore, indirectly affect many processes in atmospheric chemistry and physics such as for instance cloud condensation. To understand the surface propensity of glycine, valine, and phenylalanine at acidic, neutral, and basic pH, we used molecular dynamics (MD) simulations to investigate them at three different charge states in water. Their respective surface propensities were obtained by the means of a potential of mean force (PMF) in an umbrella sampling approach. Glycine was found to have no preference for the surface, while both valine and phenylalanine showed high propensities. Among the charge states of the surface-enriched ones, the cation, representing the amino acids at low pH, was found to have the highest affinity. Free energy decomposition revealed that the driving forces depend strongly on the nature of the amino acid and its charge state. In phenylalanine, the main factor was found to be a substantial entropy gain, likely related to the side chain, whereas in valine, hydrogen bonding to the functional groups leads to favorable energies and, in turn, affects the surface propensity. A significant gain in water-water enthalpy was seen for both valine and phenylalanine.
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Affiliation(s)
- Radost Herboth
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, 751 03 Uppsala, Sweden
| | - Geethanjali Gopakumar
- Department
of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
| | - Carl Caleman
- Department
of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
- Center
for Free-Electron Laser Science, DESY, Notkestraße 85, 226 07 Hamburg, Germany
| | - Malin Wohlert
- Department
of Materials Science and Engineering, Uppsala
University, Box 35, 751 03 Uppsala, Sweden
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18
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Huang Q, Wei H, Marr LC, Vikesland PJ. Direct Quantification of the Effect of Ammonium on Aerosol Droplet pH. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:778-787. [PMID: 33296596 DOI: 10.1021/acs.est.0c07394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ammonium is an important atmospheric constituent that dictates many environmental processes. The impact of the ammonium ion concentration on 10-50 μm aerosol droplet pH was quantified using pH nanoprobes and surface-enhanced Raman spectroscopy (SERS). Sample solutions were prepared by mixing 1 M ammonium sulfate (AS), ammonium nitrate (AN), sodium sulfate (SS), or sodium nitrate (SN) solutions with 1 M phosphate buffer (PB) at different volume ratios. Stable pH values were measured for pure PB, AS, and AN droplets at different concentrations. The centroid pH of 1 M PB droplets was ∼11, but when PB was systematically replaced with ammonium (AS- or AN-PB), the centroid pH within the droplets decreased from ≈11 to 5.5. Such a decrease was not observed in sodium (SS- or SN-PB) droplets, and no pH differences were observed between sulfate and nitrate salts. Ammonia partitioning to the gas phase in ammonium-containing droplets was evaluated to be negligible. Raman sulfate peak (∼980 cm-1) intensity measurements and surface tension measurements were conducted to investigate changes in ion distribution. The pH difference between ammonium-containing droplets and ammonium-free droplets is attributed to the alteration of the ion distribution in the presence of ammonium.
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Affiliation(s)
- Qishen Huang
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia Tech Institute of Critical Technology and Applied Science (ICTAS) Sustainable Nanotechnology Center, Blacksburg, Virginia 24061, United States
| | - Haoran Wei
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Linsey C Marr
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia Tech Institute of Critical Technology and Applied Science (ICTAS) Sustainable Nanotechnology Center, Blacksburg, Virginia 24061, United States
| | - Peter J Vikesland
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia Tech Institute of Critical Technology and Applied Science (ICTAS) Sustainable Nanotechnology Center, Blacksburg, Virginia 24061, United States
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19
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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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20
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Ault AP, Grassian VH, Carslaw N, Collins DB, Destaillats H, Donaldson DJ, Farmer DK, Jimenez JL, McNeill VF, Morrison GC, O'Brien RE, Shiraiwa M, Vance ME, Wells JR, Xiong W. Indoor Surface Chemistry: Developing a Molecular Picture of Reactions on Indoor Interfaces. Chem 2020; 6:3203-3218. [PMID: 32984643 PMCID: PMC7501779 DOI: 10.1016/j.chempr.2020.08.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chemical reactions on indoor surfaces play an important role in air quality in indoor environments, where humans spend 90% of their time. We focus on the challenges of understanding the complex chemistry that takes place on indoor surfaces and identify crucial steps necessary to gain a molecular-level understanding of environmental indoor surface chemistry: (1) elucidate key surface reaction mechanisms and kinetics important to indoor air chemistry, (2) define a range of relevant and representative surfaces to probe, and (3) define the drivers of surface reactivity, particularly with respect to the surface composition, light, and temperature. Within the drivers of surface composition are the roles of adsorbed/absorbed water associated with indoor surfaces and the prevalence, inhomogeneity, and properties of secondary organic films that can impact surface reactivity. By combining laboratory studies, field measurements, and modeling we can gain insights into the molecular processes necessary to further our understanding of the indoor environment.
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Affiliation(s)
- Andrew P Ault
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.,Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037, USA.,Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nicola Carslaw
- Department of Environment and Geography, University of York, York, North Yorkshire YO10 5NG, UK
| | - Douglas B Collins
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.,Department of Chemistry, Bucknell University, Lewisburg, PA 17837, USA
| | - Hugo Destaillats
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - D James Donaldson
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.,Department of Physical and Environmental Sciences, University of Toronto, Toronto, ON M1C 1A4, Canada
| | - Delphine K Farmer
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - Jose L Jimenez
- Department of Chemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO 80309, USA
| | - V Faye McNeill
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Glenn C Morrison
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rachel E O'Brien
- Department of Chemistry, College of William and Mary, Williamsburg, VA 23185, USA
| | - Manabu Shiraiwa
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Marina E Vance
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - J R Wells
- National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Wei Xiong
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.,Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA
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21
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Sullivan RC, Boyer-Chelmo H, Gorkowski K, Beydoun H. Aerosol Optical Tweezers Elucidate the Chemistry, Acidity, Phase Separations, and Morphology of Atmospheric Microdroplets. Acc Chem Res 2020; 53:2498-2509. [PMID: 33035055 DOI: 10.1021/acs.accounts.0c00407] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
ConspectusAerosol particles represent unique chemical environments because of their high surface area-to-volume ratio that promotes the effects of interfacial chemistry in confined environments. Properties such as viscosity, diffusivity, water content, pH, and morphology-following liquid-liquid phase separation-can strongly alter how a particle interacts with condensable vapors and reactive trace gases, thus modifying its continual evolution and environmental effects. Our understanding of this chemical evolution of atmospheric particulate matter and its environmental impacts is largely limited by our ability to directly observe how these critical particle properties respond to the addition or reactive uptake of new chemical components. Aerosol optical tweezers (AOT) stably trap particles in focused laser beams, providing positional control and the retrieval of many of these critical properties required to understand and predict the chemistry of aerosolized microdroplets. The analytical power of the AOT stems from the retrieval of the cavity-enhanced Raman spectrum induced by the trapping laser. Analysis of the whispering gallery modes (WGMs) that resonate as a standing wave around the droplet's interface, provide high accuracy measurements of the droplet's size, refractive index (and thus a measurement of composition), and can distinguish between core-shell, partially engulfed, and homogeneous morphologies. We have advanced the ability to determine the properties of the core and shell phases in biphasic droplets, including obtaining high-accuracy pH measurements. These capabilities were applied to perform AOT physical chemistry experiments on authentic secondary organic aerosol (SOA) produced directly in the AOT chamber by ozonolysis of terpene vapors. The propensity of the SOA to phase separate as a shell from a wide range of nonpolar to polar core phases was observed, along with the discovery of a stable emulsified state of SOA particles in an aqueous salt droplet. Micron-thick SOA shells did not impede the gain or loss of water or squalane from the core to the surrounding air, indicating no significant diffusional limitations to condensational growth or partitioning even under dry conditions. These experiments formed the foundation of a new framework that predicts how the phase-separated morphology of complex aerosols containing organic carbon evolves during continual atmospheric oxidation processes. Increases in oxidation state will quickly drive conversion from a partially engulfed to core-shell morphology that has dramatically different chemical reactivity since the core phase is completely concealed by the shell. The recent advances in the experimental capabilities of the AOT technique such as presented here enable novel experimental methodologies that provide insights into the chemistry and multidimensional properties of aerosol microdroplets, and how these coevolve and respond to continual chemical reactions.
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Affiliation(s)
- Ryan C. Sullivan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Hallie Boyer-Chelmo
- Department of Mechanical Engineering, University of North Dakota, Grand Forks, North Dakota 58202, United States
| | - Kyle Gorkowski
- Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Hassan Beydoun
- Atmospheric, Earth, & Energy Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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22
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Luo M, Wauer NA, Angle KJ, Dommer AC, Song M, Nowak CM, Amaro RE, Grassian VH. Insights into the behavior of nonanoic acid and its conjugate base at the air/water interface through a combined experimental and theoretical approach. Chem Sci 2020; 11:10647-10656. [PMID: 33144932 PMCID: PMC7583472 DOI: 10.1039/d0sc02354j] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/15/2020] [Indexed: 12/14/2022] Open
Abstract
The partitioning of medium-chain fatty acid surfactants such as nonanoic acid (NA) between the bulk phase and the air/water interface is of interest to a number of fields including marine and atmospheric chemistry. However, questions remain about the behavior of these molecules, the contributions of various relevant chemical equilibria, and the impact of pH, salt and bulk surfactant concentrations. In this study, the surface adsorption of nonanoic acid and its conjugate base is quantitatively investigated at various pH values, surfactant concentrations and the presence of salts. Surface concentrations of protonated and deprotonated species are dictated by surface-bulk equilibria which can be calculated from thermodynamic considerations. Notably we conclude that the surface dissociation constant of soluble surfactants cannot be directly obtained from these experimental measurements, however, we show that molecular dynamics (MD) simulation methods, such as free energy perturbation (FEP), can be used to calculate the surface acid dissociation constant relative to that in the bulk. These simulations show that nonanoic acid is less acidic at the surface compared to in the bulk solution with a pK a shift of 1.1 ± 0.6, yielding a predicted surface pK a of 5.9 ± 0.6. A thermodynamic cycle for nonanoic acid and its conjugate base between the air/water interface and the bulk phase can therefore be established. Furthermore, the effect of salts, namely NaCl, on the surface activity of protonated and deprotonated forms of nonanoic acid is also examined. Interestingly, salts cause both a decrease in the bulk pK a of nonanoic acid and a stabilization of both the protonated and deprotonated forms at the surface. Overall, these results suggest that the deprotonated medium-chain fatty acids under ocean conditions can also be present within the sea surface microlayer (SSML) present at the ocean/atmosphere interface due to the stabilization effect of the salts in the ocean. This allows the transfer of these species into sea spray aerosols (SSAs). More generally, we present a framework with which the behavior of partially soluble species at the air/water interface can be predicted from surface adsorption models and the surface pK a can be predicted from MD simulations.
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Affiliation(s)
- Man Luo
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Nicholas A Wauer
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Kyle J Angle
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Abigail C Dommer
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Meishi Song
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Christopher M Nowak
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry , University of California , La Jolla , San Diego , CA 92093 , USA . ;
- Department of Nanoengineering , Scripps Institution of Oceanography , University of California , La Jolla , San Diego , CA 92093 , USA
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23
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Su H, Cheng Y, Pöschl U. New Multiphase Chemical Processes Influencing Atmospheric Aerosols, Air Quality, and Climate in the Anthropocene. Acc Chem Res 2020; 53:2034-2043. [PMID: 32927946 PMCID: PMC7581287 DOI: 10.1021/acs.accounts.0c00246] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Atmospheric aerosols and fine particulate matter (PM2.5) are strongly affecting human health and climate in the Anthropocene,
that is, in the current era of globally pervasive and rapidly increasing
human influence on planet Earth. Poor air quality associated with high aerosol concentrations is among the
leading health risks worldwide, causing millions of attributable excess
deaths and years of life lost every year. Besides their health impact,
aerosols are also influencing climate through interactions with clouds
and solar radiation with an estimated negative total effective radiative
forcing that may compensate about half of the positive radiative forcing
of carbon dioxide but exhibits a much larger uncertainty. Heterogeneous
and multiphase chemical reactions on the surface and in the bulk of
solid, semisolid, and liquid aerosol particles have been recognized
to influence aerosol formation and transformation and thus their environmental
effects. However, atmospheric multiphase chemistry is not well understood
because of its intrinsic complexity of dealing with the matter in
multiple phases and the difficulties of distinguishing its effect
from that of gas phase reactions. Recently, research on atmospheric
multiphase chemistry received
a boost from the growing interest in understanding severe haze formation
of very high PM2.5 concentrations in polluted megacities
and densely populated regions. State-of-the-art models suggest that
the gas phase reactions, however, are not capturing the high concentrations
and rapid increase of PM2.5 observed during haze events,
suggesting a gap in our understanding of the chemical mechanisms of
aerosol formation. These haze events are characterized by high concentrations
of aerosol particles and high humidity, especially favoring multiphase
chemistry. In this Account, we review recent advances that we have
made, as well as current challenges and future perspectives for research
on multiphase chemical processes involved in atmospheric aerosol formation
and transformation. We focus on the following questions: what are
the key reaction pathways leading to aerosol formation under polluted
conditions, what is the relative importance of multiphase chemistry
versus gas-phase chemistry, and what are the implications for the
development of efficient and reliable air quality control strategies?
In particular, we discuss advances and challenges related to different
chemical regimes of sulfate, nitrate, and secondary organic aerosols
(SOAs) under haze conditions, and we synthesize new insights into
the influence of aerosol water content, aerosol pH, phase state, and
nanoparticle size effects. Overall, there is increasing evidence that
multiphase chemistry plays an important role in aerosol formation
during haze events. In contrast to the gas phase photochemical reactions,
which are self-buffered against heavy pollution, multiphase reactions
have a positive feedback mechanism, where higher particle matter levels
accelerate multiphase production, which further increases the aerosol
concentration resulting in a series of record-breaking pollution events.
We discuss perspectives to fill the gap of the current understanding
of atmospheric multiphase reactions that involve multiple physical
and chemical processes from bulk to nanoscale and from regional to
global scales. A synthetic approach combining laboratory experiments,
field measurements, instrument development, and model simulations
is suggested as a roadmap to advance future research.
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Affiliation(s)
- Hang Su
- Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Yafang Cheng
- Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Ulrich Pöschl
- Max Planck Institute for Chemistry, Mainz 55128, Germany
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24
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Cao Y, Zhang Z, Xiao H, Xie Y, Liang Y, Xiao H. How aerosol pH responds to nitrate to sulfate ratio of fine-mode particulate. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:35031-35039. [PMID: 32583119 DOI: 10.1007/s11356-020-09810-0] [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: 12/31/2019] [Accepted: 06/17/2020] [Indexed: 06/11/2023]
Abstract
Aerosol acidity (pH), one of key properties of fine-mode particulate (PM2.5), depends largely on nitrate and sulfate in particle. The mass contribution of nitrate relative to sulfate in PM2.5 has tended to increase in many regions globally, but how this change affects aerosol pH remains in debate. In this way, we measured PM2.5 ionic species and oxygen isotopic composition of nitrate in the eastern China, and predicted aerosol pH using the ISORROPIA-II model. When nitrate to sulfate molar ratio increases and thus PM2.5 is gradually enriched in ammonium nitrate (NH4NO3), aerosol pH tends to increase. The oxidation of nitrogen dioxide (NO2) by hydroxyl radical is responsible for most of nitrate formation (generally above 60%). These indicate that nitrate formation through gas-to-particle conversion involving ammonia and nitric acid results in increasing aerosol pH with increasing molar ratio of nitrate to sulfate. Conversely, aerosol pH is expected to decrease with increasing relative abundance of nitrate as ammonia emissions are lowered. Our research concludes that it should be considered to reduce aerosol NH4NO3 by reducing the precursors of nitric oxide and ammonia emissions, to substantially improve the air quality (i.e., reduce PM2.5 levels and potential nitrate deposition) in China.
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Affiliation(s)
- Yansheng Cao
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China
| | - Zhongyi Zhang
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China
| | - Hongwei Xiao
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China
| | - Yajun Xie
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China
| | - Yue Liang
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China
| | - Huayun Xiao
- Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China.
- School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China.
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25
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Ault AP. Aerosol Acidity: Novel Measurements and Implications for Atmospheric Chemistry. Acc Chem Res 2020; 53:1703-1714. [PMID: 32786333 DOI: 10.1021/acs.accounts.0c00303] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pH of a solution is one of its most fundamental chemical properties, impacting reaction pathways and kinetics across every area of chemistry. The atmosphere is no different, with the pH of the condensed phase driving key chemical reactions that ultimately impact global climate in numerous ways. The condensed phase in the atmosphere is comprised of suspended liquid or solid particles, known as the atmospheric aerosol, which are differentiated from cloud droplets by their much smaller size (primarily <10 μm). The pH of the atmospheric aerosol can enhance certain chemical reactions leading to the formation of additional condensed phase mass from lower volatility species (secondary aerosol), alter the optical and water uptake properties of particles, and solubilize metals that can act as key nutrients in nutrient-limited ecosystems or cause oxidative stress after inhalation. However, despite the importance of aerosol acidity for climate and health, our fundamental understanding of pH has been limited due to aerosol size (by number >99% of particles are <1 μm) and complexity. Within a single atmospheric particle, there can be hundreds to thousands of distinct chemical species, varying water content, high ionic strengths, and different phases (liquid, semisolid, and solid). Making aerosol analysis even more challenging, atmospheric particles are constantly evolving through heterogeneous reactions with gases and multiphase chemistry within the condensed phase. Based on these challenges, traditional pH measurements are not feasible, and, for years, indirect and proxy methods were the most common way to estimate aerosol pH, with mixed results. However, aerosol pH needs to be incorporated into climate models to accurately determine which chemical reactions are dominant in the atmosphere. Consequently, experimental measurements that probe pH in atmospherically relevant particles are sorely needed to advance our understanding of aerosol acidity.This Account describes recent advances in measurements of aerosol particle acidity, specifically three distinct methods we developed for experimentally determining particle pH. Our acid-conjugate base method uses Raman microspectroscopy to probe an acid (e.g., HSO4-) and its conjugate base (e.g., SO42-) in individual micrometer-sized particles. Our second approach is a field-deployable colorimetric method based on pH indicators (e.g., thymol blue) and cell phone imaging to provide a simple, low-cost approach to ensemble average (or bulk) pH for particles in distinct size ranges down to a few hundred nanometers in diameter. In our third method, we monitor acid-catalyzed polymer degradation of a thin film (∼23 nm) of poly(ε-caprolactone) (PCL) on silicon by individual particles with atomic force microscopy (AFM) after inertially impacting particles of different pH. These measurements are improving our understanding of aerosol pH from a fundamental physical chemistry perspective and have led to initial atmospheric measurements. The impact of aerosol pH on key atmospheric processes, such as secondary organic aerosol (SOA) formation, is discussed. Some unique findings, such as an unexpected size dependence to aerosol pH and kinetic limitations, illustrate that particles are not always in thermodynamic equilibrium with the surrounding gas. The implications of our limited, but improving, understanding of the fundamental chemical concept of pH in the atmospheric aerosol are critical for connecting chemistry and climate.
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Affiliation(s)
- Andrew P. Ault
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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26
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Song S, Hu J, Li M, Gong X, Dong C, Shuang S. Fe 3+ and intracellular pH determination based on orange fluorescence carbon dots co-doped with boron, nitrogen and sulfur. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 118:111478. [PMID: 33255057 DOI: 10.1016/j.msec.2020.111478] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 08/17/2020] [Accepted: 08/31/2020] [Indexed: 10/23/2022]
Abstract
The fluorescent boron, nitrogen and sulfur co-doped carbon dots (BNSCDs) were prepared by simple hydrothermal reaction of 4-carboxyphenylboronic acid and 2,5-diaminobenzenesulfonic acid at 200 °C for 8 h. The fluorescence of the BNSCDs could be quenched by Fe3+ based on the electron transfer between Fe3+ and BNSCDs, so a label-free, good selectivity and high sensitivity method for Fe3+determination was established with linear range and LOD of 1.5-692 μmol/L and 87 nmol/L, respectively. And then the fluorescent probe was employed for detection of Fe3+ in tap water, coal gangue, fly ash and food samples successfully. Moreover, the as-prepared BNSCDs could serve as a novel pH fluorescent probe in the range of pH 1.60-7.00, which could be attributed to the proton transfer of carboxyl groups on the surface of BNSCDs. More importantly, the pH fluorescent probe possesses fast, real-time and low toxicity, applying for intracellular pH fluorescence imaging in HIC, HIEC, LO2 and SMMC7721 cells. In view of its simplicity, timely response and outstanding compatibility, the as-fabricated BNSCDs show the potential applications in water quality and solid waste monitoring, food detection, real-time measuring of intracellular pH change in vitro.
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Affiliation(s)
- Shengmei Song
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China.
| | - Junhui Hu
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China
| | - Minglu Li
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China
| | - Xiaojuan Gong
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China.
| | - Chuan Dong
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China
| | - Shaomin Shuang
- Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China
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27
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Jia S, Chen W, Zhang Q, Krishnan P, Mao J, Zhong B, Huang M, Fan Q, Zhang J, Chang M, Yang L, Wang X. A quantitative analysis of the driving factors affecting seasonal variation of aerosol pH in Guangzhou, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 725:138228. [PMID: 32302828 DOI: 10.1016/j.scitotenv.2020.138228] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/25/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Aerosol acidity is of great interest due to its effects on atmospheric chemical processes and impact on human health; however, the driving factors of aerosol acidity have only been scarcely investigated. This study characterized the aerosol acidity during the wet and dry seasons in Guangzhou, China, and systematically analyzed the seasonal variation and the corresponding driving factors of aerosol acidity followed by the discussion of their impact on gas-aerosol partitioning of NH3 and HNO3. It was demonstrated that the pH of PM2.5 was 0.08 unit lower (more acidic) during wet season than during the dry season and the aerosol acidity varied less in South China than that in North China. Additionally, our results showed that the meteorological parameters including temperature and relative humidity have larger effect on aerosol pH variation than chemical species. Particularly, the lower temperature during dry season had the positive influence (0.38 pH unit) on aerosol pH compared to the wet season; however, the negative effect due to relative humidity (RH) and chemical species resulted in a smaller seasonal variation of aerosol pH between these two seasons. The sensitivity analysis showed that the increase of temperature has negative impact (reducing pH) on aerosol pH with an almost linear relationship, while RH and chemical species represented a two-phase linear and nonlinear effect, respectively. Finally, the calculation of gas-aerosol partitioning indicated that the temperature had the largest influence on the seasonal variation of gas-aerosol partitioning for both HNO3 and NH3 followed by liquid water content and non-ideality, while aerosol acidity imposed the lowest impact, which suggests that all the parameters including meteorological and chemical species should be comprehensively evaluated to devise a PM2.5 control strategy.
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Affiliation(s)
- Shiguo Jia
- School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Field Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Guangzhou 510275, PR China
| | - Weihua Chen
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China
| | - Qi Zhang
- School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China
| | - Padmaja Krishnan
- Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
| | - Jingying Mao
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China
| | - Buqing Zhong
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China
| | - Minjuan Huang
- School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Field Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Guangzhou 510275, PR China
| | - Qi Fan
- School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China
| | - Jinpu Zhang
- Guangdong Environmental Monitoring Center, Guangzhou 510308, PR China
| | - Ming Chang
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China
| | - Liming Yang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
| | - Xuemei Wang
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China.
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28
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Olson NE, Xiao Y, Lei Z, Ault AP. Simultaneous Optical Photothermal Infrared (O-PTIR) and Raman Spectroscopy of Submicrometer Atmospheric Particles. Anal Chem 2020; 92:9932-9939. [PMID: 32519841 DOI: 10.1021/acs.analchem.0c01495] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Physicochemical analysis of individual atmospheric aerosols at the most abundant sizes in the atmosphere (<1 μm) is analytically challenging, as hundreds to thousands of species are often present in femtoliter volumes. Vibrational spectroscopies, such as infrared (IR) and Raman, have great potential for probing functional groups in single particles at ambient pressure and temperature. However, the diffraction limit of IR radiation limits traditional IR microscopy to particles > ∼10 μm, which have less relevance to aerosol health and climate impacts. Optical photothermal infrared (O-PTIR) spectroscopy is a contactless method that circumvents diffraction limitations by using changes in the scattering intensity of a continuous wave visible laser (532 nm) to detect the photothermal expansion when a vibrational mode is excited by a tunable IR laser (QCL: 800-1800 cm-1 or OPO: 2600-3600 cm-1). Herein, we simultaneously collect O-PTIR spectra with Raman spectra at a single point for individual particles with aerodynamic diameters <400 nm (prior to impaction and spreading) at ambient temperature and pressure, by also collecting the inelastically scattered visible photons for Raman spectra. O-PTIR and Raman spectra were collected for submicrometer particles with different substrates, particle chemical compositions, and morphologies (i.e., core-shell), as well as IR mapping with submicron spatial resolution. Initial O-PTIR analysis of ambient atmospheric particles identified both inorganic and organic modes in individual sub- and supermicrometer particles. The simultaneous IR and Raman microscopy with submicrometer spatial resolution described herein has considerable potential both in atmospheric chemistry and numerous others fields (e.g., materials and biological research).
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Affiliation(s)
- Nicole E Olson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yao Xiao
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ziying Lei
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Andrew P Ault
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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29
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Freedman MA. Liquid-Liquid Phase Separation in Supermicrometer and Submicrometer Aerosol Particles. Acc Chem Res 2020; 53:1102-1110. [PMID: 32432453 DOI: 10.1021/acs.accounts.0c00093] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ConspectusThe interactions of aerosol particles with light and clouds are among the most uncertain aspects of anthropogenic climate forcings. The effects of aerosol particles on climate depend on their optical properties, heterogeneous chemistry, water uptake behavior, and ice nucleation activity. These properties in turn depend on aerosol physics and chemistry including composition, size, shape, internal structure (morphology), and phase state. The greatest numbers of particles are found at small, submicrometer sizes, and the properties of aerosol particles can differ on the nanoscale compared with measurements of bulk materials. As a result, our focus has been on characterizing the phase transitions of aerosol particles in both supermicrometer and submicrometer particles. The phase transition of particular interest for us has been liquid-liquid phase separation (LLPS), which occurs when components of a solution phase separate due to a difference in solubilities. For example, organic compounds can have limited solubility in salt solutions especially as the water content decreases, increasing the concentration of the salt solution, and causing phase separation between organic-rich and inorganic-rich phases. To characterize the systems of interest, we primarily use optical microscopy for supermicrometer particles and cryogenic-transmission microscopy for submicrometer particles.This Account details our main results to date for the phase transitions of supermicrometer particles and the morphology of submicrometer aerosol. We have found that the relative humidity (RH) at which LLPS occurs (separation RH; SRH) is highly sensitive to the composition of the particles. For supermicrometer particles, SRH decreases as the pH is lowered to atmospherically relevant values. SRH also decreases when non-phase-separating organic compounds are added to the particles. For submicrometer particles, a size dependence of morphology is observed in systems that undergo LLPS in supermicrometer particles. In the limit of slow drying rates, particles <30 nm are homogeneous and larger particles are phase-separated. This size dependence of aerosol morphology arises because small particles cannot overcome the activation barrier needed to form a new phase when phase separation occurs by a nucleation and growth mechanism. The inhibition of LLPS in small particles is observed for mixtures of ammonium sulfate with single organic compounds as well as complex organics like α-pinene secondary organic matter. The morphology of particles affects activation diameters for the formation of cloud condensation nuclei. These results more generally have implications for aerosol properties that affect the climate system. In addition, LLPS is also widely studied in materials and biological chemistry, and our results could potentially translate to implications for these fields.
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Affiliation(s)
- Miriam Arak Freedman
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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30
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Luo M, Shemesh D, Sullivan MN, Alves MR, Song M, Gerber RB, Grassian VH. Impact of pH and NaCl and CaCl2 Salts on the Speciation and Photochemistry of Pyruvic Acid in the Aqueous Phase. J Phys Chem A 2020; 124:5071-5080. [DOI: 10.1021/acs.jpca.0c01016] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Man Luo
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - Dorit Shemesh
- Institute of Chemistry and Fritz Haber Research Center, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Michael N. Sullivan
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - Michael R. Alves
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - Meishi Song
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
| | - R. Benny Gerber
- Institute of Chemistry and Fritz Haber Research Center, Hebrew University of Jerusalem, Jerusalem 91904, Israel
- Department of Chemistry, University of California, Irvine, California 92617, United States
| | - Vicki H. Grassian
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, United States
- Scripps Institution of Oceanography, University of California, San Diego, California 92037, United States
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31
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Lei Z, Bliesner SE, Mattson CN, Cooke ME, Olson NE, Chibwe K, Albert JNL, Ault AP. Aerosol Acidity Sensing via Polymer Degradation. Anal Chem 2020; 92:6502-6511. [PMID: 32227877 DOI: 10.1021/acs.analchem.9b05766] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The acidity of atmospheric aerosols is a critical property that affects the chemistry and composition of the atmosphere. Many key multiphase chemical reactions are pH-dependent, impacting processes like secondary organic aerosol formation, and need to be understood at a single particle level due to differences in particle-to-particle composition that impact both climate and health. However, the analytical challenge of measuring aerosol acidity in individual particles has limited pH measurements for fine (<2.5 μm) and coarse (2.5-10 μm) particles. This has led to a reliance on indirect methods or thermodynamic modeling, which focus on average, not individual, particle pH. Thus, new approaches are needed to probe single particle pH. In this study, a novel method for pH measurement was explored using degradation of a pH-sensitive polymer, poly(ε-caprolactone), to determine the acidity of individual submicron particles. Submicron particles of known pH (0 or 6) were deposited on a polymer film (21-25 nm thick) and allowed to react. Particles were then rinsed off, and the degradation of the polymer was characterized using atomic force microscopy and Raman microspectroscopy. After degradation, holes in the PCL films exposed to pH 0 were observed, and the loss of the carbonyl stretch was monitored at 1723 cm-1. As particle size decreased, polymer degradation increased, indicating an increase in aerosol acidity at smaller particle diameters. This study describes a new approach to determine individual particle acidity and is a step toward addressing a key measurement gap related to our understanding of atmospheric aerosol impacts on climate and health.
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Affiliation(s)
- Ziying Lei
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Samuel E Bliesner
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Claire N Mattson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Madeline E Cooke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nicole E Olson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kaseba Chibwe
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Julie N L Albert
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Andrew P Ault
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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32
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Pye HOT, Nenes A, Alexander B, Ault AP, Barth MC, Clegg SL, Collett JL, Fahey KM, Hennigan CJ, Herrmann H, Kanakidou M, Kelly JT, Ku IT, McNeill VF, Riemer N, Schaefer T, Shi G, Tilgner A, Walker JT, Wang T, Weber R, Xing J, Zaveri RA, Zuend A. The Acidity of Atmospheric Particles and Clouds. ATMOSPHERIC CHEMISTRY AND PHYSICS 2020; 20:4809-4888. [PMID: 33424953 PMCID: PMC7791434 DOI: 10.5194/acp-20-4809-2020] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semi-volatile gases such as HNO3, NH3, HCl, and organic acids and bases as well as chemical reaction rates. It has implications for the atmospheric lifetime of pollutants, deposition, and human health. Despite its fundamental role in atmospheric processes, only recently has this field seen a growth in the number of studies on particle acidity. Even with this growth, many fine particle pH estimates must be based on thermodynamic model calculations since no operational techniques exist for direct measurements. Current information indicates acidic fine particles are ubiquitous, but observationally-constrained pH estimates are limited in spatial and temporal coverage. Clouds and fogs are also generally acidic, but to a lesser degree than particles, and have a range of pH that is quite sensitive to anthropogenic emissions of sulfur and nitrogen oxides, as well as ambient ammonia. Historical measurements indicate that cloud and fog droplet pH has changed in recent decades in response to controls on anthropogenic emissions, while the limited trend data for aerosol particles indicates acidity may be relatively constant due to the semi-volatile nature of the key acids and bases and buffering in particles. This paper reviews and synthesizes the current state of knowledge on the acidity of atmospheric condensed phases, specifically particles and cloud droplets. It includes recommendations for estimating acidity and pH, standard nomenclature, a synthesis of current pH estimates based on observations, and new model calculations on the local and global scale.
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Affiliation(s)
- Havala O. T. Pye
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA
| | - Athanasios Nenes
- School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
- Institute for Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras, GR-26504, Greece
| | - Becky Alexander
- Department of Atmospheric Science, University of Washington, Seattle, WA, 98195, USA
| | - Andrew P. Ault
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA
| | - Mary C. Barth
- National Center for Atmospheric Research, Boulder, CO, 80307, USA
| | - Simon L. Clegg
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Jeffrey L. Collett
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - Kathleen M. Fahey
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA
| | - Christopher J. Hennigan
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, Baltimore, MD, 21250, USA
| | - Hartmut Herrmann
- Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Leipzig, 04318, Germany
| | - Maria Kanakidou
- Department of Chemistry, University of Crete, Voutes, Heraklion Crete, 71003, Greece
| | - James T. Kelly
- Office of Air Quality Planning & Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA
| | - I-Ting Ku
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - V. Faye McNeill
- Department of Chemical Engineering, Columbia University, New York, NY, 10027, USA
| | - Nicole Riemer
- Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana-Champaign, Illinois, 61801, USA
| | - Thomas Schaefer
- Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Leipzig, 04318, Germany
| | - Guoliang Shi
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, Nankai University, Tianjin, 300071, China
| | - Andreas Tilgner
- Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Leipzig, 04318, Germany
| | - John T. Walker
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, USA
| | - Tao Wang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Rodney Weber
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Jia Xing
- School of Environment, Tsinghua University, Beijing, 100084, China
| | - Rahul A. Zaveri
- Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Andreas Zuend
- Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Quebec, H3A 0B9, Canada
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33
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Lackey HE, Nelson GL, Lines AM, Bryan SA. Reimagining pH Measurement: Utilizing Raman Spectroscopy for Enhanced Accuracy in Phosphoric Acid Systems. Anal Chem 2020; 92:5882-5889. [PMID: 32223185 DOI: 10.1021/acs.analchem.9b05708] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Measurement of pH is an integral component of chemical studies and process control; however, traditional pH probes are difficult to utilize in harsh or complex chemical systems. Optical spectroscopy-based online monitoring offers a powerful and novel route for characterizing system parameters, such as pH, and is well adapted to deployment in harsh environments or chemically complex systems. Specifically, Raman spectroscopy combined with chemometric analysis can provide an improved method of online p[H+] measurement. Multivariate curve resolution (MCR) analysis of Raman spectra can be utilized to determine speciation as a function of p[H+], and the MCR scores assigned to each species can be used to calculate p[H+]. Subsequent chemometric modeling can be used to correlate spectral response to p[H+]. This was demonstrated with phosphoric acid, a chemical system known to challenge traditional pH probes. Raman spectra exhibit clear changes with pH due to changing speciation, and chemometric modeling can be successfully utilized to correlate those fingerprints to p[H+]. With the use of this approach, p[H+] of the phosphoric acid system can be accurately measured without foreknowledge of system conditions such as ionic strength.
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Affiliation(s)
- Hope E Lackey
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Gilbert L Nelson
- Department of Chemistry, College of Idaho, 2112 Cleveland Boulevard, Caldwell, Idaho 83605, United States
| | - Amanda M Lines
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Samuel A Bryan
- Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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34
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Chang P, Chen Z, Zhang Y, Liu Y. Direct measurement of aerosol pH in individual malonic acid and citric acid droplets under different relative humidity conditions via Raman spectroscopy. CHEMOSPHERE 2020; 241:124960. [PMID: 31590017 DOI: 10.1016/j.chemosphere.2019.124960] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/14/2019] [Accepted: 09/23/2019] [Indexed: 06/10/2023]
Abstract
Acidity of aerosol particles plays important roles in atmospheric chemistry, in turn, impacting climate system and public health. Current knowledge of acidity in atmosphere aerosols remains fairly scarce largely because of difficulty in direct measurement. On the other hand, indirect methods for estimating aerosol pH are often inconsistent with pH values predicted by thermodynamic models. Recently, a direct Raman spectroscopy method has been reported to determine pH values of acid-conjugate base equilibria systems based on Raman intensity of distinct characteristic peaks of conjugate acid-base pair. Nevertheless, for pure carboxylic acid aerosol particles, such as malonic acid (MA), characteristic peak of its conjugate base cannot be clearly observed in Raman spectra owing to small Ka value (weak acid dissociation constant), which leads to little dissociation of weak acid and low concentration of its conjugated base. As a result, pH of carboxylic acid particles cannot be directly determined by calibrating concentrations of acid and its conjugated base using the above-mentioned method. To address such an issue, we demonstrate a new approach for determining pH values of malonic acid (MA) and citric acid (CA) droplets under different relative humidity (RH) based on calibration curves. We measure Raman intensity ratios of acid solutions at different concentrations and their pH values to establish a calibration curve, and then using the intensity ratio of MA and CA droplets under different RH to determine aerosol particle pH based on calibration curves. Results have shown that aerosol pH of MA droplet decreases with a decreasing RH and pH values ranges from 1.03 to -0.12, when RH value is reduced from 90% to 26%, in good agreement with model prediction values. In addition, we also, for the first time, report pH values of CA droplets under different RH conditions and its pH values range from 1.13 to -0.74 when RH is reduced from 91% to 28%.
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Affiliation(s)
- Pianpian Chang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, PR China
| | - Zhe Chen
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, PR China
| | - Yunhong Zhang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, PR China.
| | - Yong Liu
- Department of Chemistry, University of Colorado Denver, Denver, CO, 80217, USA.
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35
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Boyer HC, Gorkowski K, Sullivan RC. In Situ pH Measurements of Individual Levitated Microdroplets Using Aerosol Optical Tweezers. Anal Chem 2020; 92:1089-1096. [PMID: 31760745 DOI: 10.1021/acs.analchem.9b04152] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The pH of microscale reaction environments controls numerous physicochemical processes, requiring a real-time pH microprobe. We present highly accurate real-time pH measurements of microdroplets using aerosol optical tweezers (AOT) and analysis of the whispering gallery modes (WGMs) contained in the cavity-enhanced Raman spectra. Uncertainties ranging from ±0.03 to 0.06 in pH for picoliter droplets are obtained through averaging Raman frames acquired at 0.5 Hz over 3.3 min. The high accuracy in pH determination is achieved by combining two independent measurements uniquely provided by the AOT approach: the anion concentration ratio from the spontaneous Raman spectra, and the total solute concentration from the refractive index retrieved from WGM analysis of the stimulated cavity-enhanced Raman spectra. pH can be determined over a range of -0.36 to 0.76 using the aqueous sodium bisulfate system. This technique enables direct measurements of pH-dependent chemical and physical changes experienced by individual microparticles and exploration of the role of pH in the chemical behavior of confined microenvironments.
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Affiliation(s)
- Hallie C Boyer
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Kyle Gorkowski
- Department of Atmospheric and Oceanic Sciences , McGill University , Montreal , Quebec H3A 0B9 , Canada
| | - Ryan C Sullivan
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
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36
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Dong X, Ohnoutek L, Yang Y, Feng Y, Wang T, Tahir MA, Valev VK, Zhang L. Cu/Ag Sphere Segment Void Array as Efficient Surface Enhanced Raman Spectroscopy Substrate for Detecting Individual Atmospheric Aerosol. Anal Chem 2019; 91:13647-13657. [PMID: 31580648 DOI: 10.1021/acs.analchem.9b02840] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Surface enhanced Raman spectroscopy (SERS) shows great promise in studying individual atmospheric aerosol. However, the lack of efficient, stable, uniform, large-array, and low-cost SERS substrates constitutes a major roadblock. Herein, a new SERS substrate is proposed for detecting individual atmospheric aerosol particles. It is based on the sphere segment void (SSV) structure of copper and silver (Cu/Ag) alloy. The SSV structure is prepared by an electrodeposition method and presents a uniform distribution, over large 2 cm2 arrays and at low cost. The substrate offers a high SERS enhancement factor (due to Ag) combined with lasting stability (due to Cu). The SSV structure of the arrays generates a high density of SERS hotspots (1.3 × 1014/cm2), making it an excellent substrate for atmospheric aerosol detection. For stimulated sulfate aerosols, the Raman signal is greatly enhanced (>50 times), an order of magnitude more than previously reported substrates for the same purpose. For ambient particles, collected and studied on a heavy haze day, the enhanced Raman signal allows ready observation of morphology and identification of chemical components, such as nitrates and sulfates. This work provides an efficient strategy for developing SERS substrate for detecting individual atmospheric aerosol.
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Affiliation(s)
- Xu Dong
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China.,Shanghai Institute of Pollution Control and Ecological Security , Shanghai 200092 , China
| | - Lukas Ohnoutek
- Centre for Photonics and Photonic Materials , University of Bath , Bath BA2 7AY , U.K.,Centre for Nanoscience and Nanotechnology , University of Bath , Bath BA2 7AY , U.K
| | - Yang Yang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China
| | - Yiqing Feng
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China
| | - Tao Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China
| | - Muhammad Ali Tahir
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China
| | - Ventsislav K Valev
- Centre for Photonics and Photonic Materials , University of Bath , Bath BA2 7AY , U.K.,Centre for Nanoscience and Nanotechnology , University of Bath , Bath BA2 7AY , U.K
| | - Liwu Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering , Fudan University , Shanghai 200433 , China.,Shanghai Institute of Pollution Control and Ecological Security , Shanghai 200092 , China
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37
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Peng X, Vasilakos P, Nenes A, Shi G, Qian Y, Shi X, Xiao Z, Chen K, Feng Y, Russell AG. Detailed Analysis of Estimated pH, Activity Coefficients, and Ion Concentrations between the Three Aerosol Thermodynamic Models. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8903-8913. [PMID: 31294542 DOI: 10.1021/acs.est.9b00181] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this work, we utilize a rich set of simulated and ground-based observational data in Tianjin, China to examine and compare the differences in aerosol acidity and composition predicted by three popular thermodynamic equilibrium models: ISORROPIA II, the Extended Aerosol Inorganics Model vision IV (E-AIM IV), and the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model (AIOMFAC). The species used to estimate aerosol acidity for both simulated and ambient data were NH4+, Na+, SO42-, NO3-, and Cl-. For simulated data, there is good agreement between ISORROPIA II and E-AIM IV predicted acidity in the forward and metastable mode, resulting from the hydrogen ion activity coefficient (γ(H+)) and the molality (m(H+)) showing opposite trends. While almost all other inorganic species concentrations are found to be similar among the three models, such is not the case for the bisulfate ion (HSO4-), which is linked to m(H+). We find that differences in predicted bisulfate between the three models primarily result from differences in the treatment of the HSO4- ↔ H+ + SO42- reaction for highly acidic conditions. This difference in bisulfate is responsible for much of the difference in estimated pH for the ambient data (average pH of 3.5 for ISORROPIA II and 3.0 for E-AIM IV).
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Affiliation(s)
- Xing Peng
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , P. R. China
- School of Civil and Environmental Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Petros Vasilakos
- School of Chemical and Biomolecular Engineering , Georgia Institute of Technology , Atlanta , Georgia , 30332 , United States
- School of Civil and Environmental Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Athanasios Nenes
- Laboratory of Atmospheric Processes and Their Impacts, School of Architecture, Civil & Environmental Engineering , Ecole Polytechnique Federale de Lausanne , CH-1015 , Lausanne , Switzerland
- Institute of Chemical Engineering Sciences , Foundation for Research and Technology Hellas , GR-26504 , Patras , Greece
| | - Guoliang Shi
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , P. R. China
| | - Yu Qian
- School of Civil and Environmental Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Xurong Shi
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , P. R. China
| | - Zhimei Xiao
- Tianjin Eco-Environmental Monitoring Center , Tianjin 300191 , P. R. China
| | - Kui Chen
- Tianjin Eco-Environmental Monitoring Center , Tianjin 300191 , P. R. China
| | - Yinchang Feng
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , P. R. China
| | - Armistead G Russell
- School of Civil and Environmental Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
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38
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Coddens EM, Angle KJ, Grassian VH. Titration of Aerosol pH through Droplet Coalescence. J Phys Chem Lett 2019; 10:4476-4483. [PMID: 31298863 DOI: 10.1021/acs.jpclett.9b00757] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The pH of aqueous aerosols, as well as cloud and fog droplets, has an important influence on the chemistry that takes place within these unique microenvironments. Utilizing conjugate acid/base pairs to infer pH changes, we investigate, for the first time, changes in aerosol pH upon coalescence. In particular, we show that the pH within individual aqueous aerosols that are ∼8 μm in diameter can be titrated via droplet coalescence in an aerosol optical tweezer. Using sulfate/bisulfate and carbonate/bicarbonate as model systems, the pH of trapped aerosols is determined before and after introduction of smaller aerosols containing a strong acid. The pH change upon coalescence with the smaller, acidic aerosol is calculated using specific ion interaction theory. Furthermore, we show that the pH of an individual aerosol can be altered along a fairly wide range of pH values, paving the way for future studies requiring rigorous pH control of an aqueous aerosol.
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Affiliation(s)
- Ellen M Coddens
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
| | - Kyle J Angle
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry , University of California San Diego , La Jolla , California 92093 , United States
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39
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Qian Y, Deng GH, Lapp J, Rao Y. Interfaces of Gas-Aerosol Particles: Relative Humidity and Salt Concentration Effects. J Phys Chem A 2019; 123:6304-6312. [PMID: 31253043 DOI: 10.1021/acs.jpca.9b03896] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The growth of aerosol particles is intimately related to chemical reactions in the gas phase and particle phase and at gas-aerosol particle interfaces. While chemical reactions in gas and particle phases are well documented, there is very little information regarding interface-related reactions. The interface of gas-aerosol particles not only facilitates a physical channel for organic species to enter and exit but also provides a necessary lane for culturing chemical reactions. The physical and chemical properties of gas-particle interfaces have not been studied extensively, nor have the reactions occurring at the interfaces been well researched. This is mainly due to the fact that there is a lack of suitable in situ interface-sensitive analytical techniques for direct measurements of interfacial properties. The motivation behind this research is to understand how interfaces play a role in the growth of aerosol particles. We have developed in situ interface-specific second harmonic scattering to examine interfacial behaviors of molecules of aerosol particles under different relative humidity (RH) and salt concentrations. Both the relative humidity and salt concentration can change the particle size and the phase of the aerosol. RH not only varies the concentration of solutes inside aerosol particles but also changes interfacial hydration in local regions. Organic molecules were found to exhibit distinct behaviors at the interfaces and bulk on NaCl particles under different RH levels. Our quantitative analyses showed that the interfacial adsorption free energies remain unchanged while interfacial areas increase as the relative humidity increases. Furthermore, the surface tension of NaCl particles decreases as the RH increases. Our experimental findings from the novel nonlinear optical scattering technique stress the importance of interfacial water behaviors on aerosol particles in the atmosphere.
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Affiliation(s)
- Yuqin Qian
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Gang-Hua Deng
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Jordan Lapp
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Yi Rao
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
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40
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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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41
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Liu C, Wang H, Guo H. Redistribution of PM 2.5 -associated nitrate and ammonium during outdoor-to-indoor transport. INDOOR AIR 2019; 29:460-468. [PMID: 30807668 DOI: 10.1111/ina.12549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 02/25/2019] [Indexed: 06/09/2023]
Abstract
Nitrate and ammonium ions are major constituents of outdoor PM2.5 . Human exposure to these ions occurs primarily indoors. To assess the adverse outcomes from exposure to them, it is necessary to quantify the relationships between outdoor and indoor PM2.5 nitrate and ammonium. The relationships for the two semi-volatile ions are more complex than those of non-volatile PM2.5 constituents (eg, sulfate, elemental carbon). This study presents a mechanistic description of their outdoor-indoor relationships that incorporates a dynamic gas-particle partitioning and key parameters such as the pH and water content of PM2.5 . Compared to measurements of nitrate and ammonium, the model has normalized mean biases of -9% and -42% and correlation coefficients of 0.95 and 0.68 for nitrate and ammonium, respectively. This suggests satisfactory agreement for nitrate, but less strong for ammonium. Sensitivity analysis on key parameters indicates that the model generally works well across a range of values typical of indoor settings. The model's performance is sensitive to pH and water content in PM2.5 , which control the gas-particle partitioning process. Indoor PM2.5 tends to be more acidic than outdoor PM2.5 , raising potential health concern. The model provides insights in exposure assessment, source apportionment, and health-composition attribution of indoor PM2.5 .
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Affiliation(s)
- Cong Liu
- School of Energy and Environment, Southeast University, Nanjing, Jiangsu, China
| | - Haixin Wang
- School of Energy and Environment, Southeast University, Nanjing, Jiangsu, China
| | - Hongyu Guo
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
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42
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Freedman MA, Ott EJE, Marak KE. Role of pH in Aerosol Processes and Measurement Challenges. J Phys Chem A 2019; 123:1275-1284. [PMID: 30586311 DOI: 10.1021/acs.jpca.8b10676] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
pH is one of the most basic chemical properties of aqueous solution, but its measurement in nanoscale aerosol particles presents many challenges. The pH of aerosol particles is of growing interest in the atmospheric chemistry community because of its demonstrated effects on heterogeneous chemistry and human health, as well as potential effects on climate. The authors have shown that phase transitions of aerosol particles are sensitive to pH, focusing on systems that undergo liquid-liquid phase separation. Currently, aerosol pH is calculated indirectly from knowledge of species present in the gas and aerosol phases through the use of thermodynamic models. From these models, ambient aerosol is expected to be highly acidic (pH ∼ 0-3). Direct measurements have focused on model systems due to the difficulty of this measurement. This area is one in which physical chemists should be encouraged to contribute because of the potential consequences for aerosol processes in the environment.
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Affiliation(s)
- Miriam Arak Freedman
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Emily-Jean E Ott
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Katherine E Marak
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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43
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Tirella PN, Craig RL, Tubbs DB, Olson NE, Lei Z, Ault AP. Extending surface enhanced Raman spectroscopy (SERS) of atmospheric aerosol particles to the accumulation mode (150-800 nm). ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2018; 20:1570-1580. [PMID: 30124713 DOI: 10.1039/c8em00276b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Due to their small size, measurements of the complex composition of atmospheric aerosol particles and their surfaces are analytically challenging. This is particularly true for microspectroscopic methods, where it can be difficult to optically identify individual particles smaller than the diffraction limit of visible light (∼350 nm) and measure their vibrational modes. Recently, surface enhanced Raman spectroscopy (SERS) has been applied to the study of aerosol particles, allowing for detection and characterization of previously undistinguishable vibrational modes. However, atmospheric particles analyzed via SERS have primarily been >1 μm to date, much larger than the diameter of the most abundant atmospheric aerosols (∼100 nm). To push SERS towards more relevant particle sizes, a simplified approach involving Ag foil substrates was developed. Both ambient particles and several laboratory-generated model aerosol systems (polystyrene latex spheres (PSLs), ammonium sulfate, and sodium nitrate) were investigated to determine SERS enhancements. SERS spectra of monodisperse, model aerosols between 400-800 nm were compared with non-SERS enhanced spectra, yielding average enhancement factors of 102 for both inorganic and organic vibrational modes. Additionally, SERS-enabled detection of 150 nm size-selected ambient particles represent the smallest individual aerosol particles analyzed by Raman microspectroscopy to date, and the first time atmospheric particles have been measured at sizes approaching the atmospheric number size distribution mode. SERS-enabled detection and identification of vibrational modes in smaller, more atmospherically-relevant particles has the potential to improve understanding of aerosol composition and surface properties, as well as their impact on heterogeneous and multiphase reactions involving aerosol surfaces.
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Affiliation(s)
- Peter N Tirella
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
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44
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Craig RL, Peterson PK, Nandy L, Lei Z, Hossain MA, Camarena S, Dodson RA, Cook RD, Dutcher CS, Ault AP. Direct Determination of Aerosol pH: Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles. Anal Chem 2018; 90:11232-11239. [DOI: 10.1021/acs.analchem.8b00586] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | | | - Lucy Nandy
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | | | | | | | | | | | - Cari S. Dutcher
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
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45
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Wei H, Vejerano EP, Leng W, Huang Q, Willner MR, Marr LC, Vikesland PJ. Aerosol microdroplets exhibit a stable pH gradient. Proc Natl Acad Sci U S A 2018; 115:7272-7277. [PMID: 29941550 PMCID: PMC6048471 DOI: 10.1073/pnas.1720488115] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Suspended aqueous aerosol droplets (<50 µm) are microreactors for many important atmospheric reactions. In droplets and other aquatic environments, pH is arguably the key parameter dictating chemical and biological processes. The nature of the droplet air/water interface has the potential to significantly alter droplet pH relative to bulk water. Historically, it has been challenging to measure the pH of individual droplets because of their inaccessibility to conventional pH probes. In this study, we scanned droplets containing 4-mercaptobenzoic acid-functionalized gold nanoparticle pH nanoprobes by 2D and 3D laser confocal Raman microscopy. Using surface-enhanced Raman scattering, we acquired the pH distribution inside approximately 20-µm-diameter phosphate-buffered aerosol droplets and found that the pH in the core of a droplet is higher than that of bulk solution by up to 3.6 pH units. This finding suggests the accumulation of protons at the air/water interface and is consistent with recent thermodynamic model results. The existence of this pH shift was corroborated by the observation that a catalytic reaction that occurs only under basic conditions (i.e., dimerization of 4-aminothiophenol to produce dimercaptoazobenzene) occurs within the high pH core of a droplet, but not in bulk solution. Our nanoparticle probe enables pH quantification through the cross-section of an aerosol droplet, revealing a spatial gradient that has implications for acid-base-catalyzed atmospheric chemistry.
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Affiliation(s)
- Haoran Wei
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
| | - Eric P Vejerano
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208
| | - Weinan Leng
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
| | - Qishen Huang
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
| | - Marjorie R Willner
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
| | - Linsey C Marr
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
| | - Peter J Vikesland
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061;
- Sustainable Nanotechnology Center, Virginia Tech Institute of Critical Technology and Applied Science, Blacksburg, VA 24061
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC 27708
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46
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Losey DJ, Ott EJE, Freedman MA. Effects of High Acidity on Phase Transitions of an Organic Aerosol. J Phys Chem A 2018; 122:3819-3828. [DOI: 10.1021/acs.jpca.8b00399] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Delanie J. Losey
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Emily-Jean E. Ott
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Miriam Arak Freedman
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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47
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Bondy AL, Craig RL, Zhang Z, Gold A, Surratt JD, Ault AP. Isoprene-Derived Organosulfates: Vibrational Mode Analysis by Raman Spectroscopy, Acidity-Dependent Spectral Modes, and Observation in Individual Atmospheric Particles. J Phys Chem A 2017; 122:303-315. [DOI: 10.1021/acs.jpca.7b10587] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Amy L. Bondy
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 United States
| | - Rebecca L. Craig
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 United States
| | - Zhenfa Zhang
- Department
of Environmental Sciences and Engineering, Gillings School of Global
Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Avram Gold
- Department
of Environmental Sciences and Engineering, Gillings School of Global
Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jason D. Surratt
- Department
of Environmental Sciences and Engineering, Gillings School of Global
Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Andrew P. Ault
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109 United States
- Department
of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
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48
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Bzdek BR, Reid JP. Perspective: Aerosol microphysics: From molecules to the chemical physics of aerosols. J Chem Phys 2017; 147:220901. [DOI: 10.1063/1.5002641] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Bryan R. Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
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49
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Rapf RJ, Dooley MR, Kappes K, Perkins RJ, Vaida V. pH Dependence of the Aqueous Photochemistry of α-Keto Acids. J Phys Chem A 2017; 121:8368-8379. [DOI: 10.1021/acs.jpca.7b08192] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Rebecca J. Rapf
- Department of Chemistry and
Biochemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Michael R. Dooley
- Department of Chemistry and
Biochemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Keaten Kappes
- Department of Chemistry and
Biochemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Russell J. Perkins
- Department of Chemistry and
Biochemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Veronica Vaida
- Department of Chemistry and
Biochemistry and Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, Colorado 80309, United States
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50
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Bondy AL, Wang B, Laskin A, Craig RL, Nhliziyo MV, Bertman SB, Pratt KA, Shepson PB, Ault AP. Inland Sea Spray Aerosol Transport and Incomplete Chloride Depletion: Varying Degrees of Reactive Processing Observed during SOAS. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:9533-9542. [PMID: 28732168 DOI: 10.1021/acs.est.7b02085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Multiphase reactions involving sea spray aerosol (SSA) impact trace gas budgets in coastal regions by acting as a reservoir for oxidized nitrogen and sulfur species, as well as being a source of halogen gases (HCl, ClNO2, etc.). Whereas most studies of multiphase reactions on SSA have focused on marine environments, far less is known about SSA transported inland. Herein, single-particle measurements of SSA are reported at a site >320 km from the Gulf of Mexico, with transport times of 7-68 h. Samples were collected during the Southern Oxidant and Aerosol Study (SOAS) in June-July 2013 near Centreville, Alabama. SSA was observed in 93% of 42 time periods analyzed. During two marine air mass periods, SSA represented significant number fractions of particles in the accumulation (0.2-1.0 μm, 11%) and coarse (1.0-10.0 μm, 35%) modes. Chloride content of SSA particles ranged from full to partial depletion, with 24% of SSA particles containing chloride (mole fraction of Cl/Na ≥ 0.1, 90% chloride depletion). Both the frequent observation of SSA at an inland site and the range of chloride depletion observed suggest that SSA may represent an underappreciated inland sink for NOx/SO2 oxidation products and a source of halogen gases.
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Affiliation(s)
- Amy L Bondy
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Bingbing Wang
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99354, United States
| | - Alexander Laskin
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99354, United States
| | - Rebecca L Craig
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Manelisi V Nhliziyo
- Department of Chemistry, Tuskegee University , Tuskegee, Alabama 36088, United States
| | - Steven B Bertman
- Department of Chemistry, Western Michigan University , Kalamazoo, Michigan 49008, United States
| | - Kerri A Pratt
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Paul B Shepson
- Departments of Chemistry and Earth, Atmospheric, and Planetary Sciences, Purdue University , West Lafayette, Indiana 47907, United States
| | - Andrew P Ault
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
- Department of Environmental Health Sciences, University of Michigan , Ann Arbor, Michigan 48109, United States
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