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Enami S, Numadate N, Hama T. Atmospheric Intermediates at the Air-Water Interface. J Phys Chem A 2024; 128:5419-5434. [PMID: 38968003 PMCID: PMC11264275 DOI: 10.1021/acs.jpca.4c02889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 07/07/2024]
Abstract
The air-water interface (AWI) is a ubiquitous reaction field different from the bulk phase where unexpected reactions and physical processes often occur. The AWI is a region where air contacts cloud droplets, aerosol particles, the ocean surface, and biological surfaces such as fluids that line human epithelia. In Earth's atmosphere, short-lived intermediates are expected to be generated at the AWI during multiphase reactions. Recent experimental developments have enabled the direct detection of atmospherically relevant, short-lived intermediates at the AWI. For example, spray ionization mass spectrometric analysis of water microjets exposed to a gaseous mixture of ozone and water vapor combined with a 266 nm laser flash photolysis system (LFP-SIMS) has been used to directly probe organic peroxyl radicals (RO2·) produced by interfacial hydroxyl radicals (OH·) + organic compound reactions. OH· emitted immediately after the laser flash photolysis of carboxylic acid at the gas-liquid interface have been directly detected by time-resolved, laser-induced florescence techniques that can be used to study atmospheric multiphase photoreactions. In this Featured Article, we show some recent experimental advances in the detection of atmospherically important intermediates at the AWI and the associated reaction mechanisms. We also discuss current challenges and future prospects for atmospheric multiphase chemistry.
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Affiliation(s)
- Shinichi Enami
- Department
of Chemistry, Graduate School of Science and Technology, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Naoki Numadate
- Department
of Chemistry, Graduate School of Science and Technology, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Tetsuya Hama
- Komaba
Institute for Science and Department of Basic Science, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
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2
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Knorr N, Rosselli S, Nelles G. Electrostatic Surface Charging by Water Dewetting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:14321-14333. [PMID: 38967322 DOI: 10.1021/acs.langmuir.4c00906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Water dewetting generates static electricity. We reviewed historical experiments of this phenomenon, and we studied the charging of polymer slides and metal electrode supported polymer films withdrawn vertically from a pool of aqueous solutions. For pure water, charging was negative and surface charge densities increased with the speed of dewetting, which we explain by the thermally activated entrainment of nanometer-sized water droplets or clusters charged by unbalanced adsorbed electric double-layer ions. Surface charge densities increased for reduced polymer film thickness following a power law, which we explain by reduced discharge of the entrained water volumes. At low salinity c ≲ 10 μM, charging was proportional to electrokinetic interfacial charge densities: the negative charging was increased for alkaline solutions and for most salts at μM concentrations and the charge polarity was inversed to positive for a cationic surfactant, a salt with a highly positively charged cation, and for a strong acid at approximately pH 4. Charging was reduced again for c ≳ 100 μM, especially at high dewetting speeds and for chaotropic ions, which we explain by the entrainment of larger and more discharged droplets. We determined adsorption energies of the charged water clusters on the dewetted surface from thermally stimulated discharge of the charged polymer slides and we show that the surface charge distribution, imaged by charged toner powders and measured microscopically by Kelvin probe force microscopy, is a record of the dewetting process that provides spatial and kinetic information about the three-phase contact line motion.
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Affiliation(s)
- Nikolaus Knorr
- Stuttgart Laboratory 2, Sony Europe B.V., Hedelfinger Strasse 61, Stuttgart D-70327, Germany
| | - Silvia Rosselli
- Stuttgart Laboratory 2, Sony Europe B.V., Hedelfinger Strasse 61, Stuttgart D-70327, Germany
| | - Gabriele Nelles
- Stuttgart Laboratory 2, Sony Europe B.V., Hedelfinger Strasse 61, Stuttgart D-70327, Germany
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3
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Seki T, Yu CC, Chiang KY, Yu X, Sun S, Bonn M, Nagata Y. Spontaneous Appearance of Triiodide Covering the Topmost Layer of the Iodide Solution Interface Without Photo-Oxidation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:3830-3837. [PMID: 38353041 PMCID: PMC10902846 DOI: 10.1021/acs.est.3c08243] [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: 02/28/2024]
Abstract
Ions containing iodine atoms at the vapor-aqueous solution interfaces critically affect aerosol growth and atmospheric chemistry due to their complex chemical nature and multivalency. While the surface propensity of iodide ions has been intensely discussed in the context of the Hofmeister series, the stability of various ions containing iodine atoms at the vapor-water interface has been debated. Here, we combine surface-specific sum-frequency generation (SFG) vibrational spectroscopy with ab initio molecular dynamics simulations to examine the extent to which iodide ions cover the aqueous surface. The SFG probe of the free O-D stretch mode of heavy water indicates that the free O-D group density decreases drastically at the interface when the bulk NaI concentration exceeds ∼2 M. The decrease in the free O-D group density is attributed to the spontaneous appearance of triiodide that covers the topmost interface rather than to the surface adsorption of iodide. This finding demonstrates that iodide is not surface-active, yet the highly surface-active triiodide is generated spontaneously at the water-air interface, even under dark and oxygen-free conditions. Our study provides an important first step toward clarifying iodine chemistry and pathways for aerosol formation.
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Affiliation(s)
- Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561, Japan
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kuo-Yang Chiang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Shumei Sun
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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4
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Seki T, Yu CC, Chiang KY, Greco A, Yu X, Matsumura F, Bonn M, Nagata Y. Ions Speciation at the Water-Air Interface. J Am Chem Soc 2023; 145:10622-10630. [PMID: 37139910 DOI: 10.1021/jacs.3c00517] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In typical aqueous systems, including naturally occurring sweet and salt water and tap water, multiple ion species are co-solvated. At the water-air interface, these ions are known to affect the chemical reactivity, aerosol formation, climate, and water odor. Yet, the composition of ions at the water interface has remained enigmatic. Here, using surface-specific heterodyne-detected sum-frequency generation spectroscopy, we quantify the relative surface activity of two co-solvated ions in solution. We find that more hydrophobic ions are speciated to the interface due to the hydrophilic ions. Quantitative analysis shows that the interfacial hydrophobic ion population increases with decreasing interfacial hydrophilic ion population at the interface. Simulations show that the solvation energy difference between the ions and the intrinsic surface propensity of ions determine the extent of an ion's speciation by other ions. This mechanism provides a unified view of the speciation of monatomic and polyatomic ions at electrolyte solution interfaces.
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Affiliation(s)
- Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Aomori, Japan
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Kuo-Yang Chiang
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Alessandro Greco
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Fumiki Matsumura
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
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5
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Wei W, Chen X, Wang X. Nanopore Sensing Technique for Studying the Hofmeister Effect. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200921. [PMID: 35484475 DOI: 10.1002/smll.202200921] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/22/2022] [Indexed: 06/14/2023]
Abstract
The nanopore sensing technique is an emerging method of detecting single molecules, and extensive research has gone into various fields, including nanopore sequencing and other applications of single-molecule studies. Recently, several researchers have explored the specific ion effects in nanopore channels, enabling a unique understanding of the Hofmeister effect at the single-molecule level. Herein, the recent advances of using nanopore sensing techniques are reviewed to study the Hofmeister effect and the physicochemical mechanism of this process is attempted. The challenges and goals are also discussed for the future in this field.
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Affiliation(s)
- Weichen Wei
- Department of Nanoengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Xiaojuan Chen
- Department of Nanoengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Xuejiao Wang
- Fujian Provincial University Engineering Research Center of Industrial Biocatalysis, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, 350007, China
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6
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Gallo A, Musskopf NH, Liu X, Yang Z, Petry J, Zhang P, Thoroddsen S, Im H, Mishra H. On the formation of hydrogen peroxide in water microdroplets. Chem Sci 2022; 13:2574-2583. [PMID: 35340850 PMCID: PMC8890092 DOI: 10.1039/d1sc06465g] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/13/2022] [Indexed: 02/06/2023] Open
Abstract
Recent reports on the formation of hydrogen peroxide (H2O2) in water microdroplets produced via pneumatic spraying or capillary condensation have garnered significant attention. How covalent bonds in water could break under such mild conditions challenges our textbook understanding of physical chemistry and water. While there is no definitive answer, it has been speculated that ultrahigh electric fields at the air-water interface are responsible for this chemical transformation. Here, we report on our comprehensive experimental investigation of H2O2 formation in (i) water microdroplets sprayed over a range of liquid flow-rates, (shearing) air flow rates, and air composition, and (ii) water microdroplets condensed on hydrophobic substrates formed via hot water or humidifier under controlled air composition. Specifically, we assessed the contributions of the evaporative concentration and shock waves in sprays and the effects of trace O3(g) on the H2O2 formation. Glovebox experiments revealed that the H2O2 formation in water microdroplets was most sensitive to the air-borne ozone (O3) concentration. In the absence of O3(g), we could not detect H2O2(aq) in sprays or condensates (detection limit ≥250 nM). In contrast, microdroplets exposed to atmospherically relevant O3(g) concentration (10-100 ppb) formed 2-30 µM H2O2(aq), increasing with the gas-liquid surface area, mixing, and contact duration. Thus, the water surface area facilitates the O3(g) mass transfer, which is followed by the chemical transformation of O3(aq) into H2O2(aq). These findings should also help us understand the implications of this chemistry in natural and applied contexts.
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Affiliation(s)
- Adair Gallo
- Interfacial Lab (iLab), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Nayara H Musskopf
- Interfacial Lab (iLab), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Xinlei Liu
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Ziqiang Yang
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Jeferson Petry
- Interfacial Lab (iLab), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Peng Zhang
- Interfacial Lab (iLab), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Sigurdur Thoroddsen
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Hong Im
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Himanshu Mishra
- Interfacial Lab (iLab), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
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7
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Gu AY, Musgrave C, Goddard WA, Hoffmann MR, Colussi AJ. Role of Ferryl Ion Intermediates in Fast Fenton Chemistry on Aqueous Microdroplets. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14370-14377. [PMID: 34213313 DOI: 10.1021/acs.est.1c01962] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In the aqueous environment, FeII ions enhance the oxidative potential of ozone and hydrogen peroxide by generating the reactive oxoiron species (ferryl ion, FeIVO2+) and hydroxyl radical (·OH) via Fenton chemistry. Herein, we investigate factors that control the pathways of these reactive intermediates in the oxidation of dimethyl sulfoxide (Me2SO) in FeII solutions reacting with O3 in both bulk-phase water and on the surfaces of aqueous microdroplets. Electrospray ionization mass spectrometry is used to quantify the formation of dimethyl sulfone (Me2SO2, from FeIVO2+ + Me2SO) and methanesulfonate (MeSO3-, from ·OH + Me2SO) over a wide range of FeII and O3 concentrations and pH. In addition, the role of environmentally relevant organic ligands on the reaction kinetics was also explored. The experimental results show that Fenton chemistry proceeds at a rate ∼104 times faster on microdroplets than that in bulk-phase water. Since the production of MeSO3- is initiated by ·OH radicals at diffusion-controlled rates, experimental ratios of Me2SO2/MeSO3- > 102 suggest that FeIVO2+ is the dominant intermediate under all conditions. Me2SO2 yields in the presence of ligands, L, vary as volcano-plot functions of E0(LFeIVO2++ O2/LFe2+ + O3) reduction potentials calculated by DFT with a maximum achieved in the case of L≡oxalate. Our findings underscore the key role of ferryl FeIVO2+ intermediates in Fenton chemistry taking place on aqueous microdroplets.
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Affiliation(s)
- Alan Y Gu
- Linde Laboratories, California Institute of Technology, Pasadena, California 91125, United States
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Charles Musgrave
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - William A Goddard
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Michael R Hoffmann
- Linde Laboratories, California Institute of Technology, Pasadena, California 91125, United States
| | - Agustín J Colussi
- Linde Laboratories, California Institute of Technology, Pasadena, California 91125, United States
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8
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Nauruzbayeva J, Sun Z, Gallo A, Ibrahim M, Santamarina JC, Mishra H. Electrification at water-hydrophobe interfaces. Nat Commun 2020; 11:5285. [PMID: 33082321 PMCID: PMC7576844 DOI: 10.1038/s41467-020-19054-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 09/28/2020] [Indexed: 11/23/2022] Open
Abstract
The mechanisms leading to the electrification of water when it comes in contact with hydrophobic surfaces remains a research frontier in chemical science. A clear understanding of these mechanisms could, for instance, aid the rational design of triboelectric generators and micro- and nano-fluidic devices. Here, we investigate the origins of the excess positive charges incurred on water droplets that are dispensed from capillaries made of polypropylene, perfluorodecyltrichlorosilane-coated glass, and polytetrafluoroethylene. Results demonstrate that the magnitude and sign of electrical charges vary depending on: the hydrophobicity/hydrophilicity of the capillary; the presence/absence of a water reservoir inside the capillary; the chemical and physical properties of aqueous solutions such as pH, ionic strength, dielectric constant and dissolved CO2 content; and environmental conditions such as relative humidity. Based on these results, we deduce that common hydrophobic materials possess surface-bound negative charge. Thus, when these surfaces are submerged in water, hydrated cations form an electrical double layer. Furthermore, we demonstrate that the primary role of hydrophobicity is to facilitate water-substrate separation without leaving a significant amount of liquid behind. These results advance the fundamental understanding of water-hydrophobe interfaces and should translate into superior materials and technologies for energy transduction, electrowetting, and separation processes, among others.
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Affiliation(s)
- Jamilya Nauruzbayeva
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Zhonghao Sun
- King Abdullah University of Science and Technology, Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC), Division of Physical Science and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Adair Gallo
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Mahmoud Ibrahim
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - J Carlos Santamarina
- King Abdullah University of Science and Technology, Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC), Division of Physical Science and Engineering, Thuwal, 23955 - 6900, Saudi Arabia
| | - Himanshu Mishra
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955 - 6900, Saudi Arabia.
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9
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Moreno C, Baeza-Romero MT. A kinetic model for ozone uptake by solutions and aqueous particles containing I - and Br -, including seawater and sea-salt aerosol. Phys Chem Chem Phys 2019; 21:19835-19856. [PMID: 31497813 DOI: 10.1039/c9cp03430g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The heterogeneous interactions of gaseous ozone (O3) with seawater and with sea-salt aerosols are known to generate volatile halogen species, which, in turn, lead to further destruction of O3. Here, a kinetic model for the interaction of ozone (O3) with Br- and I- solutions and aqueous particles has been proposed that satisfactorily explains previous literature studies about this process. Apart from the aqueous-phase reactions X- + O3 (X = I, Br), the interaction also involves the surface reactions X- + O3 that occur via O3 adsorption on the aqueous surface. In single salt solutions and aerosols, the partial order in ozone and the total order of the surface reactions are one, but the apparent total order is second order because the number of ozone sites where reaction can occur is equal to the surficial concentration of X- ([X-]surf). In the presence of Cl-, the surface reactions are enhanced by a factor equal to , where and . Therefore, we have inferred that Cl- acts as a catalyst in the surface reactions X- + O3. The model has been applied to estimate ozone uptake by the reaction with these halides in/on seawater and in/on sea-salt aerosol, where it has been concluded that the Cl--catalyzed surface reaction is important relative to total ozone uptake and should therefore be considered to model Y/YO (Y = I, Br, Cl) levels in the troposphere.
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Affiliation(s)
- Carolina Moreno
- Escuela de Ingeniería Industrial y Aeroespacial, Universidad de Castilla-La Mancha, 45071, Toledo, Spain.
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10
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Qiu J, Ishizuka S, Tonokura K, Sato K, Inomata S, Enami S. Effects of pH on Interfacial Ozonolysis of α-Terpineol. J Phys Chem A 2019; 123:7148-7155. [PMID: 31329444 DOI: 10.1021/acs.jpca.9b05434] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Acidity changes the physical properties of atmospheric aerosol particles and the mechanisms of reactions that occur therein and on the surface. Here, we used surface-sensitive pneumatic ionization mass spectrometry to investigate the effects of pH on the heterogeneous reactions of aqueous α-terpineol (C10H17OH), a representative monoterpene alcohol, with gaseous ozone. Rapid (≤10 μs) ozonolysis of α-terpineol produced Criegee intermediates (CIs, zwitterionic/diradical carbonyl oxides) on the surface of water microjets. We studied the effects of microjet bulk pH (1-11) on the formation of functionalized carboxylate and α-hydroxy-hydroperoxide chloride adduct (HH-Cl-) products generated by isomerization and hydration of α-terpineol CIs, respectively. Compared with the signal at pH ≈ 6, the mass spectral signal of HH-Cl- was less intense under both basic and more acidic conditions, whereas the intensity of the functionalized carboxylate signal increased with increasing pH up to 4 and then remained constant. The decrease of HH-Cl- signals at bulk pH values of >6 is attributable to the accumulation of OH- at the air-water interface that suppresses the relative abundance of hydrophilic HH and Cl-. The present study suggests that α-terpineol in ambient aqueous organic aerosols will be converted into much lower volatile and potentially toxic organic hydroperoxides during the heterogeneous ozonolysis.
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Affiliation(s)
- Junting Qiu
- Graduate School of Frontier Sciences , The University of Tokyo , 5-1-5 Kashiwanoha , Kashiwa 277-8563 , Japan
| | - Shinnosuke Ishizuka
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
| | - Kenichi Tonokura
- Graduate School of Frontier Sciences , The University of Tokyo , 5-1-5 Kashiwanoha , Kashiwa 277-8563 , Japan
| | - Kei Sato
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
| | - Satoshi Inomata
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
| | - Shinichi Enami
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
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11
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Enami S, Hoffmann MR, Colussi AJ. Iodide Accelerates the Processing of Biogenic Monoterpene Emissions on Marine Aerosols. ACS OMEGA 2019; 4:7574-7580. [PMID: 31459850 PMCID: PMC6648763 DOI: 10.1021/acsomega.9b00024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/15/2019] [Indexed: 06/10/2023]
Abstract
Marine photosynthetic organisms emit organic gases, including the polyolefins isoprene (C5H8) and monoterpenes (MTPs, C10H16), into the boundary layer. Their atmospheric processing produces particles that influence cloud formation and growth and, as a result, the Earth's radiation balance. Here, we report that the heterogeneous ozonolysis of dissolved α-pinene by O3(g) on aqueous surfaces is dramatically accelerated by I-, an anion enriched in the ocean upper microlayer and sea spray aerosols (SSAs). In our experiments, liquid microjets of α-pinene solutions, with and without added I-, are dosed with O3(g) for τ < 10 μs and analyzed online by pneumatic ionization mass spectrometry. In the absence of I-, α-pinene does not detectably react with O3(g) under present conditions. In the presence of ≥ 0.01 mM I-, in contrast, new signals appear at m/z = 169 (C9H13O3 -), m/z = 183 (C10H15O3 -), m/z = 199 (C10H15O4 -), m/z = 311 (C10H16IO3 -), and m/z = 461 (C20H30IO4 -), plus m/z = 175 (IO3 -), and m/z = 381 (I3 -). Collisional fragmentation splits CO2 from C9H13O3 -, C10H15O3 - and C10H15O4 -, and I- plus IO- from C10H16IO3 - as expected from a trioxide IOOO•C10H16 - structure. We infer that the oxidative processing of α-pinene on aqueous surfaces is significantly accelerated by I- via the formation of IOOO- intermediates that are more reactive than O3. A mechanism in which IOOO- reacts with α-pinene (and likely with other unsaturated species) in competition with its isomerization to IO3 - accounts for present results and the fact that soluble iodine in SSA is mostly present as iodine-containing organic species rather than the thermodynamically more stable iodate. By this process, a significant fraction of biogenic MTPs and other unsaturated gases may be converted to water-soluble species rather than emitted to the atmosphere.
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Affiliation(s)
- Shinichi Enami
- National
Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
| | - Michael R. Hoffmann
- Linde
Center for Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
| | - Agustín J. Colussi
- Linde
Center for Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
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12
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Detecting Intermediates and Products of Fast Heterogeneous Reactions on Liquid Surfaces via Online Mass Spectrometry. ATMOSPHERE 2019. [DOI: 10.3390/atmos10020047] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
One of the research priorities in atmospheric chemistry is to advance our understanding of heterogeneous reactions and their effect on the composition of the troposphere. Chemistry on aqueous surfaces is particularly important because of their ubiquity and expanse. They range from the surfaces of oceans (360 million km2), cloud and aerosol drops (estimated at ~10 trillion km2) to the fluid lining the human lung (~150 m2). Typically, ambient air contains reactive gases that may affect human health, influence climate and participate in biogeochemical cycles. Despite their importance, atmospheric reactions between gases and solutes on aqueous surfaces are not well understood and, as a result, generally overlooked. New, surface-specific techniques are required that detect and identify the intermediates and products of such reactions as they happen on liquids. This is a tall order because genuine interfacial reactions are faster than mass diffusion into bulk liquids, and may produce novel species in low concentrations. Herein, we review evidence that validates online pneumatic ionization mass spectrometry of liquid microjets exposed to reactive gases as a technique that meets such requirements. Next, we call attention to results obtained by this approach on reactions of gas-phase ozone, nitrogen dioxide and hydroxyl radicals with various solutes on aqueous surfaces. The overarching conclusion is that the outermost layers of aqueous solutions are unique media, where most equilibria shift and reactions usually proceed along new pathways, and generally faster than in bulk water. That the rates and mechanisms of reactions at air-aqueous interfaces may be different from those in bulk water opens new conceptual frameworks and lines of research, and adds a missing dimension to atmospheric chemistry.
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13
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Li L, Hoffmann MR, Colussi AJ. Role of Nitrogen Dioxide in the Production of Sulfate during Chinese Haze-Aerosol Episodes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2686-2693. [PMID: 29378118 DOI: 10.1021/acs.est.7b05222] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Haze events in China megacities involve the rapid oxidation of SO2 to sulfate aerosol. Given the weak photochemistry that takes place in these optically thick hazes, it has been hypothesized that SO2 is mostly oxidized by NO2 emissions in the bulk of pH > 5.5 aerosols. Because NO2(g) dissolution in water is very slow and aerosols are more acidic, we decided to test such a hypothesis. Herein, we report that > 95% of NO2(g) disproportionates [2NO2(g) + H2O(l) = H+ + NO3-(aq) + HONO (R1)] upon hitting the surface of NaHSO3 aqueous microjets for < 50 μs, thereby giving rise to strong NO3- ( m/ z 62) signals detected by online electrospray mass spectrometry, rather than oxidizing HSO3- ( m/ z 81) to HSO4- ( m/ z 97) in the relevant pH 3-6 range. Because NO2(g) will be consumed via R1 on the surface of typical aerosols, the oxidation of S(IV) may in fact be driven by the HONO/NO2- generated therein. S(IV) heterogeneous oxidation rates are expected to primarily depend on the surface density and liquid water content of the aerosol, which are enhanced by fine aerosol and high humidity. Whether aerosol acidity affects the oxidation of S(IV) by HONO/NO2- remains to be elucidated.
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Affiliation(s)
- Lijie Li
- Department of Environmental Science & Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Michael R Hoffmann
- Department of Environmental Science & Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Agustín J Colussi
- Department of Environmental Science & Engineering , California Institute of Technology , Pasadena , California 91125 , United States
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14
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Enami S, Hoffmann MR, Colussi AJ. Extensive H-atom abstraction from benzoate by OH-radicals at the air-water interface. Phys Chem Chem Phys 2018; 18:31505-31512. [PMID: 27827491 DOI: 10.1039/c6cp06652f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Much is known about OH-radical chemistry in the gas-phase and bulk water. Important atmospheric and biological processes, however, involve little investigated OH-radical reactions at aqueous interfaces with hydrophobic media. Here, we report the online mass-specific identification of the products and intermediates generated on the surface of aqueous (H2O, D2O) benzoate-h5 and -d5 microjets by ∼8 ns ˙OH(g) pulses in air at 1 atm. Isotopic labeling lets us unambiguously identify the phenylperoxyl radicals that ensue H-abstraction from the aromatic ring and establish a lower bound (>26%) to this process as it takes place in the interfacial water nanolayers probed by our experiments. The significant extent of H-abstraction vs. its negligible contribution both in the gas-phase and bulk water underscores the unique properties of the air-water interface as a reaction medium. The enhancement of H-atom abstraction in interfacial water is ascribed, in part, to the relative destabilization of a more polar transition state for OH-radical addition vs. H-abstraction due to incomplete hydration at the low water densities prevalent therein.
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Affiliation(s)
- Shinichi Enami
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
| | - Michael R Hoffmann
- Linde Center for Global Environmental Science, California Institute of Technology, California 91125, USA.
| | - Agustín J Colussi
- Linde Center for Global Environmental Science, California Institute of Technology, California 91125, USA.
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15
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Ishizuka S, Fujii T, Matsugi A, Sakamoto Y, Hama T, Enami S. Controlling factors of oligomerization at the water surface: why is isoprene such a unique VOC? Phys Chem Chem Phys 2018; 20:15400-15410. [DOI: 10.1039/c8cp01551a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The interfacial oligomerization of isoprene is facilitated by the resonance stabilization through the formation of a tertiary carbocation with a conjugated CC bond pair, and electron enrichment induced by the neighboring methyl group.
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Affiliation(s)
- Shinnosuke Ishizuka
- Institute of Low Temperature Science
- Hokkaido University
- Sapporo 060-0819
- Japan
- National Institute for Environmental Studies
| | - Tomihide Fujii
- Graduate School of Global Environmental Studies
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Akira Matsugi
- Research Institute of Science for Safety and Sustainability
- National Institute of Advanced Industrial Science and Technology
- Tsukuba 305-8569
- Japan
| | - Yosuke Sakamoto
- Graduate School of Global Environmental Studies
- Kyoto University
- Kyoto 606-8501
- Japan
- Graduate School of Human and Environmental Studies
| | - Tetsuya Hama
- Institute of Low Temperature Science
- Hokkaido University
- Sapporo 060-0819
- Japan
| | - Shinichi Enami
- National Institute for Environmental Studies
- Tsukuba 305-8506
- Japan
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16
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Investigation of Hofmeister effects in ultra-dilute solutions at the water/silica interface using electrokinetic current generation. J Electroanal Chem (Lausanne) 2017. [DOI: 10.1016/j.jelechem.2017.10.068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Okur H, Chen Y, Wilkins D, Roke S. The Jones-Ray effect reinterpreted: Surface tension minima of low ionic strength electrolyte solutions are caused by electric field induced water-water correlations. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.06.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Enami S, Fujii T, Sakamoto Y, Hama T, Kajii Y. Carboxylate Ion Availability at the Air–Water Interface. J Phys Chem A 2016; 120:9224-9234. [DOI: 10.1021/acs.jpca.6b08868] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shinichi Enami
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Tomihide Fujii
- Graduate School of Global Environmental
Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Yosuke Sakamoto
- Graduate School of Global Environmental
Studies, Kyoto University, Kyoto 606-8501, Japan
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8316, Japan
| | - Tetsuya Hama
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Yoshizumi Kajii
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
- Graduate School of Global Environmental
Studies, Kyoto University, Kyoto 606-8501, Japan
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8316, Japan
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19
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Rizzuto AM, Irgen-Gioro S, Eftekhari-Bafrooei A, Saykally RJ. Broadband Deep UV Spectra of Interfacial Aqueous Iodide. J Phys Chem Lett 2016; 7:3882-3885. [PMID: 27635463 DOI: 10.1021/acs.jpclett.6b01931] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The behavior of ions at aqueous interfaces influences vital processes in many fields but has long remained a subject of controversy. Over the past decade, counterintuitive surface concentration enhancement of several ions in aqueous solution has been demonstrated via nonlinear laser spectroscopy and mass spectrometry. While the evidence for significant ion enhancement at the air-water interface is convincing, the mechanism remains incompletely understood. Toward this end, we present the full broadband DUV-SFG spectrum of the charge-transfer-to-solvent (CTTS) band of interfacial aqueous iodide measured in a single laser shot with a newly developed broadband deep UV-SFG technique, clearly revealing a ∼8 nm redshift and a significant linewidth narrowing relative to bulk solution spectra. KI and NaI solutions yield indistinguishable results. Additionally, we observe a dramatic change in the relative intensities of the J = 3/2 and 1/2 CTTS transitions.
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Affiliation(s)
- Anthony M Rizzuto
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Shawn Irgen-Gioro
- Department of Chemistry, University of California , Berkeley, California 94720, United States
| | - Ali Eftekhari-Bafrooei
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Richard J Saykally
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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20
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Enami S, Hoffmann MR, Colussi AJ. Halogen Radical Chemistry at Aqueous Interfaces. J Phys Chem A 2016; 120:6242-8. [DOI: 10.1021/acs.jpca.6b04219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Shinichi Enami
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Michael R. Hoffmann
- Linde
Center for Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
| | - A. J. Colussi
- Linde
Center for Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
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21
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Enami S, Sakamoto Y. OH-Radical Oxidation of Surface-Active cis-Pinonic Acid at the Air–Water Interface. J Phys Chem A 2016; 120:3578-87. [DOI: 10.1021/acs.jpca.6b01261] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shinichi Enami
- The
Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
- Research
Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Yosuke Sakamoto
- Graduate
School of Human and Environmental Studies, Kyoto University, Kyoto, 606-8316, Japan
- Graduate
School of Global Environmental Studies, Kyoto University, Kyoto, 606-8501, Japan
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22
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Enami S, Sakamoto Y, Hara K, Osada K, Hoffmann MR, Colussi AJ. "Sizing" Heterogeneous Chemistry in the Conversion of Gaseous Dimethyl Sulfide to Atmospheric Particles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:1834-1843. [PMID: 26761399 DOI: 10.1021/acs.est.5b05337] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The oxidation of biogenic dimethyl sulfide (DMS) emissions is a global source of cloud condensation nuclei. The amounts of the nucleating H2SO4(g) species produced in such process, however, remain uncertain. Hydrophobic DMS is mostly oxidized in the gas phase into H2SO4(g) + DMSO(g) (dimethyl sulfoxide), whereas water-soluble DMSO is oxidized into H2SO4(g) in the gas phase and into SO4(2-) + MeSO3(-) (methanesulfonate) on water surfaces. R = MeSO3(-)/(non-sea-salt SO4(2-)) ratios would therefore gauge both the strength of DMS sources and the extent of DMSO heterogeneous oxidation if Rhet = MeSO3(-)/SO4(2-) for DMSO(aq) + ·OH(g) were known. Here, we report that Rhet = 2.7, a value obtained from online electrospray mass spectra of DMSO(aq) + ·OH(g) reaction products that quantifies the MeSO3(-) produced in DMSO heterogeneous oxidation on aqueous aerosols for the first time. On this basis, the inverse R dependence on particle radius in size-segregated aerosol collected over Syowa station and Southern oceans is shown to be consistent with the competition between DMSO gas-phase oxidation and its mass accommodation followed by oxidation on aqueous droplets. Geographical R variations are thus associated with variable contributions of the heterogeneous pathway to DMSO atmospheric oxidation, which increase with the specific surface area of local aerosols.
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Affiliation(s)
- Shinichi Enami
- The Hakubi Center for Advanced Research, Kyoto University , Kyoto 606-8302, Japan
- Research Institute for Sustainable Humanosphere, Kyoto University , Uji 611-0011, Japan
- PRESTO, Japan Science and Technology Agency , Kawaguchi 332-0012, Japan
| | - Yosuke Sakamoto
- Faculty of Environmental Earth Science, Hokkaido University , Sapporo 060-0610, Japan
| | - Keiichiro Hara
- Department of Earth Science System, Fukuoka University , Fukuoka 814-0180, Japan
| | - Kazuo Osada
- Graduate School of Environmental Studies, Nagoya University , Nagoya 464-8601, Japan
| | - Michael R Hoffmann
- Linde Center for Global Environmental Science, California Institute of Technology , California 91125, United States
| | - Agustín J Colussi
- Linde Center for Global Environmental Science, California Institute of Technology , California 91125, United States
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23
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Hung HM, Hoffmann MR. Oxidation of Gas-Phase SO2 on the Surfaces of Acidic Microdroplets: Implications for Sulfate and Sulfate Radical Anion Formation in the Atmospheric Liquid Phase. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:13768-76. [PMID: 26270804 DOI: 10.1021/acs.est.5b01658] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The oxidation of SO2(g) on the interfacial layers of microdroplet surfaces was investigated using a spray-chamber reactor coupled to an electrospray ionization mass spectrometer. Four major ions, HSO3(-), SO3(•-), SO4(•-) and HSO4(-), were observed as the SO2(g)/N2(g) gas-mixture was passed through a suspended microdroplet flow, where the residence time in the dynamic reaction zone was limited to a few hundred microseconds. The relatively high signal intensities of SO3(•-), SO4(•-), and HSO4(-) compared to those of HSO3(-) as observed at pH < 3 without addition of oxidants other than oxygen suggests an efficient oxidation pathway via sulfite and sulfate radical anions on droplets possibly via the direct interfacial electron transfer from HSO3(-) to O2. The concentrations of HSO3(-) in the aqueous aerosol as a function of pH were controlled by the deprotonation of hydrated sulfur dioxide, SO2·H2O, which is also affected by the pH dependent uptake coefficient. When H2O2(g) was introduced into the spray chamber simultaneously with SO2(g), HSO3(-) is rapidly oxidized to form bisulfate in the pH range of 3 to 5. Conversion to sulfate was less at pH < 3 due to relatively low HSO3(-) concentration caused by the fast interfacial reactions. The rapid oxidation of SO2(g) on the acidic microdroplets was estimated as 1.5 × 10(6) [S(IV)] (M s(-1)) at pH ≤ 3. In the presence of acidic aerosols, this oxidation rate is approximately 2 orders of magnitude higher than the rate of oxidation with H2O2(g) at a typical atmospheric H2O2(g) concentration of 1 ppb. This finding highlights the relative importance of the acidic surfaces for SO2 oxidation in the atmosphere. Surface chemical reactions on aquated aerosol surfaces, as observed in this study, are overlooked in most atmospheric chemistry models. These reaction pathways may contribute to the rapid production of sulfate aerosols that is often observed in regions impacted by acidic haze aerosol such as Beijing and other megacities around the world.
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Affiliation(s)
- Hui-Ming Hung
- Department of Atmospheric Sciences, National Taiwan University , No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan
| | - Michael R Hoffmann
- Linde Center for Global Environmental Science, California Institute of Technology Linde-Robinson Laboratory , Pasadena, California 91125, United States
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24
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Duignan TT, Parsons DF, Ninham BW. Hydronium and hydroxide at the air–water interface with a continuum solvent model. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.06.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Heiles S, Cooper RJ, DiTucci MJ, Williams ER. Hydration of guanidinium depends on its local environment. Chem Sci 2015; 6:3420-3429. [PMID: 28706704 PMCID: PMC5490459 DOI: 10.1039/c5sc00618j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 04/14/2015] [Indexed: 01/10/2023] Open
Abstract
Hydration of gaseous guanidinium (Gdm+) with up to 100 water molecules attached was investigated using infrared photodissociation spectroscopy in the hydrogen stretch region between 2900 and 3800 cm-1. Comparisons to IR spectra of low-energy computed structures indicate that at small cluster size, water interacts strongly with Gdm+ with three inner shell water molecules each accepting two hydrogen bonds from adjacent NH2 groups in Gdm+. Comparisons to results for tetramethylammonium (TMA+) and Na+ enable structural information for larger clusters to be obtained. The similarity in the bonded OH region for Gdm(H2O)20+vs. Gdm(H2O)100+ and the similarity in the bonded OH regions between Gdm+ and TMA+ but not Na+ for clusters with <50 water molecules indicate that Gdm+ does not significantly affect the hydrogen-bonding network of water molecules at large size. These results indicate that the hydration around Gdm+ changes for clusters with more than about eight water molecules to one in which inner shell water molecules only accept a single H-bond from Gdm+. More effective H-bonding drives this change in inner-shell water molecule binding to other water molecules. These results show that hydration of Gdm+ depends on its local environment, and that Gdm+ will interact with water even more strongly in an environment where water is partially excluded, such as the surface of a protein. This enhanced hydration in a limited solvation environment may provide new insights into the effectiveness of Gdm+ as a protein denaturant.
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Affiliation(s)
- Sven Heiles
- Department of Chemistry , University of California , B42 Hildebrand Hall , Berkeley , CA 94720 , USA .
| | - Richard J Cooper
- Department of Chemistry , University of California , B42 Hildebrand Hall , Berkeley , CA 94720 , USA .
| | - Matthew J DiTucci
- Department of Chemistry , University of California , B42 Hildebrand Hall , Berkeley , CA 94720 , USA .
| | - Evan R Williams
- Department of Chemistry , University of California , B42 Hildebrand Hall , Berkeley , CA 94720 , USA .
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26
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Enami S, Hoffmann MR, Colussi AJ. Stepwise Oxidation of Aqueous Dicarboxylic Acids by Gas-Phase OH Radicals. J Phys Chem Lett 2015; 6:527-534. [PMID: 26261974 DOI: 10.1021/jz502432j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A leading source of uncertainty in predicting the climate and health effects of secondary organic aerosol (SOA) is how its composition changes over their atmospheric lifetimes. Because dicarboxylic acid (DCA) homologues are widespread in SOA, their distribution provides an ideal probe of both aerosol age and the oxidative power of the atmosphere along its trajectory. Here we report, for the first time, on the oxidation of DCA(aq) by ·OH(g) at the air-water interface. We found that exposure of aqueous HOOC-Rn-COOH (Rn = C2H4, C3H6, C4H8, C5H10, and C6H12) microjets to ∼10 ns ·OH(g) pulses from the 266 nm laser photolysis of O3(g)/O2(g)/H2O(g) mixtures yields the corresponding (n-1) species O═C(H)-Rn-1-COO(-)/HOOC-Rn-1-COO(-), in addition to an array of closed-shell HOOC-Rn(-H)(OOH)-COO(-), HOOC-Rn(-2H)(═O)-COO(-), HOOC-Rn(-H)(OH)-COO(-), and radical HOOC-Rn(-H)(OO·)-COO(-) species. Oxalic and malonic acids, which are shown to be significantly less hydrophobic and reactive than their higher homologues, will predictably accumulate in SOA, in accordance with field observations.
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Affiliation(s)
- Shinichi Enami
- †The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
- ‡Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
- §PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Michael R Hoffmann
- ∥Linde Center for Global Environmental Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States
| | - Agustín J Colussi
- ∥Linde Center for Global Environmental Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States
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27
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Riboni F, Selli E, Hoffmann MR, Colussi AJ. Homogeneous Reduction of CO2 by Photogenerated Pyridinyl Radicals. J Phys Chem A 2014; 119:4433-8. [DOI: 10.1021/jp509735z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Francesca Riboni
- Linde Center for
Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
- Department
of Chemistry, University of Milan, via Golgi 19, 20133 Milano, Italy
| | - Elena Selli
- Department
of Chemistry, University of Milan, via Golgi 19, 20133 Milano, Italy
| | - M. R. Hoffmann
- Linde Center for
Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
| | - A. J. Colussi
- Linde Center for
Global Environmental Science, California Institute of Technology, Pasadena, California 91125, United States
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28
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Enami S, Hoffmann MR, Colussi AJ. In situ mass spectrometric detection of interfacial intermediates in the oxidation of RCOOH(aq) by gas-phase OH-radicals. J Phys Chem A 2014; 118:4130-7. [PMID: 24841316 DOI: 10.1021/jp503387e] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Products and intermediates of the oxidation of aqueous alkanoic acids initiated by gas-phase hydroxyl radicals, ·OH(g), at the air-water interface were detected by mass spectrometry in a novel setup under various experimental conditions. Exposure of submillimolar RCOOH (R = methyl, n-pentyl, n-heptyl) aqueous microjets to ∼10 ns ·OH(g) pulses from the 266 nm laser flash photolysis of O3(g)/O2(g)/H2O(g) mixtures yielded an array of interfacial species that were unambiguously and simultaneously identified in situ by online electrospray mass spectrometry. We found that peroxyl radicals R(-H)(COO(-))OO· react within 50 μs to produce alcohols R(-H)(COO(-))OH and carbonyls R(-2H)(COO(-))═O via competitive Russell and Bennett-Summers mechanisms. We confirmed the formation of hydroperoxides R(-H)(COO(-))OOH in experiments performed in D2O. To our knowledge, this is the first report on the prompt and simultaneous detection of products and peroxyl/peroxide intermediates in the heterogeneous oxidation of aqueous organics initiated by ·OH(g).
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Affiliation(s)
- Shinichi Enami
- The Hakubi Center for Advanced Research, Kyoto University , Kyoto 606-8302, Japan
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29
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Merk V, Rehbock C, Becker F, Hagemann U, Nienhaus H, Barcikowski S. In situ non-DLVO stabilization of surfactant-free, plasmonic gold nanoparticles: effect of Hofmeister's anions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4213-22. [PMID: 24720469 DOI: 10.1021/la404556a] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Specific ion effects ranking in the Hofmeister sequence are ubiquitous in biochemical, industrial, and atmospheric processes. In this experimental study specific ion effects inexplicable by the classical DLVO theory have been investigated at curved water-metal interfaces of gold nanoparticles synthesized by a laser ablation process in liquid in the absence of any organic stabilizers. Notably, ion-specific differences in colloidal stability occurred in the Hückel regime at extraordinarily low salinities below 50 μM, and indications of a direct influence of ion-specific effects on the nanoparticle formation process are found. UV-vis, zeta potential, and XPS measurements help to elucidate coagulation properties, electrokinetic potential, and the oxidation state of pristine gold nanoparticles. The results clearly demonstrate that stabilization of ligand-free gold nanoparticles scales proportionally with polarizability and antiproportionally with hydration of anions located at defined positions in a direct Hofmeister sequence of anions. These specific ion effects might be due to the adsorption of chaotropic anions (Br(-), SCN(-), or I(-)) at the gold/water interface, leading to repulsive interactions between the partially oxidized gold particles during the nanoparticle formation process. On the other hand, kosmotropic anions (F(-) or SO4(2-)) seem to destabilize the gold colloid, whereas Cl(-) and NO3(-) give rise to an intermediate stability. Quantification of surface charge density indicated that particle stabilization is dominated by ion adsorption and not by surface oxidation. Fundamental insights into specific ion effects on ligand-free aqueous gold nanoparticles beyond purely electrostatic interactions are of paramount importance in biomedical or catalytic applications, since colloidal stability appears to depend greatly on the type of salt rather than on the amount.
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Affiliation(s)
- Vivian Merk
- Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen CENIDE , Universtitaetsstrasse 5, 45141 Essen, Germany
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30
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Enami S, Colussi AJ. Ion-Specific Long-Range Correlations on Interfacial Water Driven by Hydrogen Bond Fluctuations. J Phys Chem B 2014; 118:1861-6. [DOI: 10.1021/jp411385u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shinichi Enami
- The Hakubi
Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Agustín J. Colussi
- Linde Center for Global Environmental
Science, California Institute of Technology, Pasadena, California 91125, United States
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31
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Cassou CA, Williams ER. Anions in electrothermal supercharging of proteins with electrospray ionization follow a reverse Hofmeister series. Anal Chem 2014; 86:1640-7. [PMID: 24410546 PMCID: PMC3983018 DOI: 10.1021/ac403398j] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
The
effects of different anions on the extent of electrothermal
supercharging of proteins from aqueous ammonium and sodium salt solutions
were investigated. Sulfate and hydrogen phosphate are the most effective
anions at producing high charge state protein ions from buffered aqueous
solution, whereas iodide and perchlorate are ineffective with electrothermal
supercharging. The propensity for these anions to produce high charge
state protein ions follows the following trend: sulfate > hydrogen
phosphate > thiocyanate > bicarbonate > chloride > formate
≈
bromide > acetate > iodide > perchlorate. This trend correlates
with
the reverse Hofmeister series over a wide range of salt concentrations
(1 mM to 2 M) and with several physical properties, including solvent
surface tension, anion viscosity B-coefficient, and anion surface/bulk
partitioning coefficient, all of which are related to the Hofmeister
series. The effectiveness of electrothermal supercharging does not
depend on bubble formation, either from thermal degradation of the
buffer or from coalescence of dissolved gas. These results provide
evidence that the effect of different ions in the formation of high
charge state ions by electrothermal supercharging is largely a result
of Hofmeister effects on protein stability leading to protein unfolding
in the heated ESI droplet.
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Affiliation(s)
- Catherine A Cassou
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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Abstract
In a fundamental process throughout nature, reduced iron unleashes the oxidative power of hydrogen peroxide into reactive intermediates. However, notwithstanding much work, the mechanism by which Fe(2+) catalyzes H2O2 oxidations and the identity of the participating intermediates remain controversial. Here we report the prompt formation of O=Fe(IV)Cl3(-) and chloride-bridged di-iron O=Fe(IV) · Cl · Fe(II)Cl4(-) and O=Fe(IV) · Cl · Fe(III)Cl5(-) ferryl species, in addition to Fe(III)Cl4(-), on the surface of aqueous FeCl2 microjets exposed to gaseous H2O2 or O3 beams for <50 μs. The unambiguous identification of such species in situ via online electrospray mass spectrometry let us investigate their individual dependences on Fe(2+), H2O2, O3, and H(+) concentrations, and their responses to tert-butanol (an · OH scavenger) and DMSO (an O-atom acceptor) cosolutes. We found that (i) mass spectra are not affected by excess tert-butanol, i.e., the detected species are primary products whose formation does not involve · OH radicals, and (ii) the di-iron ferryls, but not O=Fe(IV)Cl3(-), can be fully quenched by DMSO under present conditions. We infer that interfacial Fe(H2O)n(2+) ions react with H2O2 and O3 >10(3) times faster than Fe(H2O)6(2+) in bulk water via a process that favors inner-sphere two-electron O-atom over outer-sphere one-electron transfers. The higher reactivity of di-iron ferryls vs. O=Fe(IV)Cl3(-) as O-atom donors implicates the electronic coupling of mixed-valence iron centers in the weakening of the Fe(IV)-O bond in poly-iron ferryl species.
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Affiliation(s)
- Shinichi Enami
- The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Yosuke Sakamoto
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo 060-0610, Japan; and
| | - Agustín J. Colussi
- Linde Center for Global Environmental Science, California Institute of Technology, CA 91125
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Tian R, Yang G, Li H, Gao X, Liu X, Zhu H, Tang Y. Activation energies of colloidal particle aggregation: towards a quantitative characterization of specific ion effects. Phys Chem Chem Phys 2014; 16:8828-36. [DOI: 10.1039/c3cp54813a] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Hama T, Watanabe N. Surface Processes on Interstellar Amorphous Solid Water: Adsorption, Diffusion, Tunneling Reactions, and Nuclear-Spin Conversion. Chem Rev 2013; 113:8783-839. [DOI: 10.1021/cr4000978] [Citation(s) in RCA: 211] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tetsuya Hama
- Institute of Low Temperature
Science, Hokkaido University, N19W8 Kita-ku, Sapporo, Hokkaido 060-0819, Japan
| | - Naoki Watanabe
- Institute of Low Temperature
Science, Hokkaido University, N19W8 Kita-ku, Sapporo, Hokkaido 060-0819, Japan
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35
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Ou S, Cui D, Patel S. Liquid-vapor interfacial properties of aqueous solutions of guanidinium and methyl guanidinium chloride: influence of molecular orientation on interface fluctuations. J Phys Chem B 2013; 117:11719-31. [PMID: 23937431 DOI: 10.1021/jp405862p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The guanidinium cation (C(NH2)3(+)) is a highly stable cation in aqueous solution due to its efficient solvation by water molecules and resonance stabilization of the charge. Its salts increase the solubility of nonpolar molecules ("salting-in") and decrease the ordering of water. It is one of the strongest denaturants used in biophysical studies of protein folding. We investigate the behavior of guanidinium and its derivative, methyl guanidinium (an amino acid analogue) at the air-water surface, using atomistic molecular dynamics (MD) simulations and calculation of potentials of mean force. Methyl guanidinium cation is less excluded from the air-water surface than guanidinium cation, but both cations show orientational dependence of surface affinity. Parallel orientations of the guanidinium ring (relative to the Gibbs dividing surface) show pronounced free energy minima in the interfacial region, while ring orientations perpendicular to the GDS exhibit no discernible surface stability. Calculations of surface fluctuations demonstrate that, near the air-water surface, the parallel-oriented cations generate significantly greater interfacial fluctuations compared to other orientations, which induces more long-ranged perturbations and solvent density redistribution. Our results suggest a strong correlation with induced interfacial fluctuations and ion surface stability. These results have implications for interpreting molecular-level, mechanistic action of this osmolyte's interaction with hydrophobic interfaces as they impact protein denaturation (solubilization).
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Affiliation(s)
- Shuching Ou
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
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36
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Ou S, Patel S. Temperature dependence and energetics of single ions at the aqueous liquid-vapor interface. J Phys Chem B 2013; 117:6512-23. [PMID: 23537166 DOI: 10.1021/jp401243m] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate temperature-dependence of free energetics with two single halide anions, I(-) and Cl(-), crossing the aqueous liquid-vapor interface through molecular dynamics simulations. The result shows that I(-) has a modest surface stability of 0.5 kcal/mol at 300 K and the stability decreases as the temperature increases, indicating the surface adsorption process for the anion is entropically disfavored. In contrast, Cl(-) shows no such surface state at all temperatures. Decomposition of free energetics reveals that water-water interactions provide a favorable enthalpic contribution, while the desolvation of ion induces an increase in free energy. Calculations of surface fluctuations demonstrate that I(-) generates significantly greater interfacial fluctuations compared to Cl(-). The fluctuation is attributed to the malleability of the solvation shells, which allows for more long-ranged perturbations and solvent density redistribution induced by I(-) as the anion approaches the liquid-vapor interface. The increase in temperature of the solvent enhances the inherent thermally excited fluctuations and consequently reduces the relative contribution from anion to surface fluctuations, which is consistent with the decrease in surface stability of I(-). Our results indicate a strong correlation with induced interfacial fluctuations and anion surface stability; moreover, resulting temperature dependent behavior of induced fluctuations suggests the possibility of a critical level of induced fluctuations associated with surface stability.
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Affiliation(s)
- Shuching Ou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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37
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Enami S, Colussi AJ. Long-range specific ion-ion interactions in hydrogen-bonded liquid films. J Chem Phys 2013; 138:184706. [DOI: 10.1063/1.4803652] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Enami S, Colussi AJ. Long-range Hofmeister effects of anionic and cationic amphiphiles. J Phys Chem B 2013; 117:6276-81. [PMID: 23621428 DOI: 10.1021/jp401285f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Specific ion effects at aqueous interfaces play key roles in many important phenomena. We recently reported that ions interact specifically over unexpectedly long distances on the surface of sub-micromolar electrolyte solutions (Enami et al. J. Chem. Phys. 2012, 136, 154707). Whether the anionic and cationic headgroups of the organic amphiphiles present at most water/hydrophobe interfaces act similarly or display new behaviors, however, is not known. Here we report the results of experiments in which we apply online electrospray ionization mass spectrometry (ESI-MS) to investigate how carboxylate, RCOO(-) (R = CH3, C5H11, C7H15), and alkylammonium, R'(CH3)3N(+) (R' = CH3, C14H29), ions affect the ratio χ = I(-)/Br(-) at the aerial interface of 1 μM (NaI + NaBr) aqueous solutions. We found that χ is systematically but selectively depressed by these ionic amphiphiles and minimally affected by the neutral surfactant 1-octanol. The depressing effects induced by cationic headgroups are stronger than those caused by anionic surfactants and always increase with the length of the alkyl chains.
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Affiliation(s)
- Shinichi Enami
- The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302, Japan.
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39
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Abstract
Differences in the extent of protonation of functional groups lying on either side of water-hydrophobe interfaces are deemed essential to enzymatic catalysis, molecular recognition, bioenergetic transduction, and atmospheric aerosol-gas exchanges. The sign and range of such differences, however, remain conjectural. Herein we report experiments showing that gaseous carboxylic acids RCOOH(g) begin to deprotonate on the surface of water significantly more acidic than that supporting the dissociation of dissolved acids RCOOH(aq). Thermodynamic analysis indicates that > 6 H(2)O molecules must participate in the deprotonation of RCOOH(g) on water, but quantum mechanical calculations on a model air-water interface predict that such event is hindered by a significant kinetic barrier unless OH(-) ions are present therein. Thus, by detecting RCOO(-) we demonstrate the presence of OH(-) on the aerial side of on pH > 2 water exposed to RCOOH(g). Furthermore, because in similar experiments the base (Me)(3)N(g) is protonated only on pH < 4 water, we infer that the outer surface of water is Brønsted neutral at pH ∼3 (rather than at pH 7 as bulk water), a value that matches the isoelectric point of bubbles and oil droplets in independent electrophoretic experiments. The OH(-) densities sensed by RCOOH(g) on the aerial surface of water, however, are considerably smaller than those at the (>1 nm) deeper shear planes probed in electrophoresis, thereby implying the existence of OH(-) gradients in the interfacial region. This fact could account for the weak OH(-) signals detected by surface-specific spectroscopies.
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40
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Buchner F, Ritze HH, Beutler M, Schultz T, Hertel IV, Lübcke A. Role of alkali cations for the excited state dynamics of liquid water near the surface. J Chem Phys 2012; 137:024503. [DOI: 10.1063/1.4732582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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