51
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Heindel JP, Hao H, LaCour RA, Head-Gordon T. Spontaneous Formation of Hydrogen Peroxide in Water Microdroplets. J Phys Chem Lett 2022; 13:10035-10041. [PMID: 36264238 DOI: 10.1021/acs.jpclett.2c01721] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
There is accumulating evidence that many chemical reactions are accelerated by several orders of magnitude in micrometer-sized aqueous or organic liquid droplets compared to their corresponding bulk liquid phase. However, the molecular origin of the enhanced rates remains unclear as in the case of spontaneous appearance of 1 μM hydrogen peroxide in water microdroplets. In this Letter, we consider the range of ionization energies and whether interfacial electric fields of a microdroplet can feasibly overcome the high energy step from hydroxide ions (OH-) to hydroxyl radicals (OH•) in a primary H2O2 mechanism. We find that the vertical ionization energies (VIEs) of partially solvated OH- ions are greatly lowered relative to the average VIE in the bulk liquid, unlike the case of the Cl- anion which shows no reduction in the VIEs regardless of solvation environment. Overall reduced hydrogen-bonding and undercoordination of OH- are structural features that are more readily present at the air-water interface, where the energy scale for ionization can be matched by statistically probable electric field values.
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Affiliation(s)
- Joseph P Heindel
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Hongxia Hao
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
| | - R Allen LaCour
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Teresa Head-Gordon
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
- Departments of Bioengineering and Chemical and Biomolecular EngineeringUniversity of California, Berkeley, California94720, United States
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52
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Shu Z, Pan Z, Wang X, He H, Yan S, Zhu X, Song W, Wang Z. Sunlight-Induced Interfacial Electron Transfer of Ferrihydrite under Oxic Conditions: Mineral Transformation and Redox Active Species Production. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14188-14197. [PMID: 36098650 DOI: 10.1021/acs.est.2c04594] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Fe(II)-catalyzed ferrihydrite transformation under anoxic conditions has been intensively studied, while such mechanisms are insufficient to be applied in oxic environments with depleted Fe(II). Here, we investigated expanded pathways of sunlight-driven ferrihydrite transformation in the presence of dissolved oxygen, without initial addition of dissolved Fe(II). We found that sunlight significantly facilitated the transformation of ferrihydrite to goethite compared to that under dark conditions. Redox active species (hole-electron pairs, reactive radicals, and Fe(II)) were produced from the ferrihydrite interface via the photoinduced electron transfer processes. Experiments with systematically varied wet chemistry conditions probed the relative contributions of three pathways for the production of hydroxyl radicals: (1) oxidation of water (5.0%); (2) reduction of dissolved oxygen (40.9%); and (3) photolysis of Fe(III)-hydroxyl complexes (54.1%). Results also showed superoxide radicals as the main oxidant for Fe(II) reoxidation under acidic conditions, thus promoting the ferrihydrite transformation. The presence of inorganic ions (chloride, sulfate, and nitrate) did not only affect the hydrolysis and precipitation of Fe(III) but also the generation of radicals via photoinduced charge transfer reactions. The involvement of redox active species and the accompanying mineral transformations would exert a profound effect on the fate of multivalent elements and organic contaminants in aquatic environments.
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Affiliation(s)
- Zhipeng Shu
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Zezhen Pan
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Xingxing Wang
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Haohua He
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Shuwen Yan
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Xiuping Zhu
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Weihua Song
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
| | - Zimeng Wang
- Cluster of Interfacial Processes Against Pollution (CIPAP), Department of Environmental Science and Engineering, Fudan University, Shanghai200438, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai200092, China
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53
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Dabodiya TS, Yu H, Li M, Zhang X. Sequential droplet reactions for surface-bound gold nanocrater array. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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54
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Donaldson DJ. Experimental Confirmation of H 2O 2 Adsorption at the Water-Air Interface. J Phys Chem A 2022; 126:5647-5653. [PMID: 35960909 PMCID: PMC9422982 DOI: 10.1021/acs.jpca.2c04373] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/01/2022] [Indexed: 11/28/2022]
Abstract
Recent work has reported that hydrogen peroxide is formed at the air-water interface. Given the reduced solvation environment there, this process could give rise to enhanced production of OH from H2O2 photolysis at the interface. These considerations give some importance to understanding the adsorption thermochemistry of hydrogen peroxide. Although there are two molecular dynamics studies that provide the adsorption free energy, to date there is no experimental verification that H2O2 adsorbs at the air-water interface. Here we use glancing-angle Raman spectroscopy to follow the surface adsorption behavior of this molecule. Using standard states of 1 mol L-1 for each of the bulk and surface phases yields a ΔG° of -5 kJ mol-1 at 293 K, comparable to that obtained for DMSO.
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Affiliation(s)
- D. James Donaldson
- Department
of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S
3H6, Canada
- Department
of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
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55
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Xing D, Meng Y, Yuan X, Jin S, Song X, Zare RN, Zhang X. Capture of Hydroxyl Radicals by Hydronium Cations in Water Microdroplets. Angew Chem Int Ed Engl 2022; 61:e202207587. [DOI: 10.1002/anie.202207587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 12/26/2022]
Affiliation(s)
- Dong Xing
- College of Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Renewable Energy Conversion and Storage Center (RECAST) Frontiers Science Center for New Organic Matter Nankai University Tianjin 300071 China
- Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192 China
- Beijing National Laboratory for Molecular Sciences Beijing 100190 China
| | - Yifan Meng
- Department of Chemistry Stanford University Stanford CA 94305 USA
| | - Xu Yuan
- College of Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Renewable Energy Conversion and Storage Center (RECAST) Frontiers Science Center for New Organic Matter Nankai University Tianjin 300071 China
- Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192 China
- Beijing National Laboratory for Molecular Sciences Beijing 100190 China
| | - Shuihui Jin
- College of Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Renewable Energy Conversion and Storage Center (RECAST) Frontiers Science Center for New Organic Matter Nankai University Tianjin 300071 China
- Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192 China
- Beijing National Laboratory for Molecular Sciences Beijing 100190 China
| | - Xiaowei Song
- Department of Chemistry Stanford University Stanford CA 94305 USA
| | - Richard N. Zare
- Department of Chemistry Stanford University Stanford CA 94305 USA
| | - Xinxing Zhang
- College of Chemistry Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Renewable Energy Conversion and Storage Center (RECAST) Frontiers Science Center for New Organic Matter Nankai University Tianjin 300071 China
- Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192 China
- Beijing National Laboratory for Molecular Sciences Beijing 100190 China
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56
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Water-solid contact electrification causes hydrogen peroxide production from hydroxyl radical recombination in sprayed microdroplets. Proc Natl Acad Sci U S A 2022; 119:e2209056119. [PMID: 35914139 PMCID: PMC9371641 DOI: 10.1073/pnas.2209056119] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Contact electrification between water and a solid surface is crucial for physicochemical processes at water-solid interfaces. However, the nature of the involved processes remains poorly understood, especially in the initial stage of the interface formation. Here we report that H2O2 is spontaneously produced from the hydroxyl groups on the solid surface when contact occurred. The density of hydroxyl groups affects the H2O2 yield. The participation of hydroxyl groups in H2O2 generation is confirmed by mass spectrometric detection of 18O in the product of the reaction between 4-carboxyphenylboronic acid and 18O-labeled H2O2 resulting from 18O2 plasma treatment of the surface. We propose a model for H2O2 generation based on recombination of the hydroxyl radicals produced from the surface hydroxyl groups in the water-solid contact process. Our observations show that the spontaneous generation of H2O2 is universal on the surfaces of soil and atmospheric fine particles in a humid environment.
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57
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Xie X, Wang Y, Siu SY, Chan CW, Zhu Y, Zhang X, Ge J, Ren K. Microfluidic synthesis as a new route to produce novel functional materials. BIOMICROFLUIDICS 2022; 16:041301. [PMID: 36035887 PMCID: PMC9410731 DOI: 10.1063/5.0100206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
By geometrically constraining fluids into the sub-millimeter scale, microfluidics offers a physical environment largely different from the macroscopic world, as a result of the significantly enhanced surface effects. This environment is characterized by laminar flow and inertial particle behavior, short diffusion distance, and largely enhanced heat exchange. The recent two decades have witnessed the rapid advances of microfluidic technologies in various fields such as biotechnology; analytical science; and diagnostics; as well as physical, chemical, and biological research. On the other hand, one additional field is still emerging. With the advances in nanomaterial and soft matter research, there have been some reports of the advantages discovered during attempts to synthesize these materials on microfluidic chips. As the formation of nanomaterials and soft matters is sensitive to the environment where the building blocks are fed, the unique physical environment of microfluidics and the effectiveness in coupling with other force fields open up a lot of possibilities to form new products as compared to conventional bulk synthesis. This Perspective summarizes the recent progress in producing novel functional materials using microfluidics, such as generating particles with narrow and controlled size distribution, structured hybrid materials, and particles with new structures, completing reactions with a quicker rate and new reaction routes and enabling more effective and efficient control on reactions. Finally, the trend of future development in this field is also discussed.
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Affiliation(s)
- Xinying Xie
- Department of Chemistry, Hong Kong Baptist University, Hong Kong 999077, China
| | - Yisu Wang
- Department of Chemistry, Hong Kong Baptist University, Hong Kong 999077, China
| | - Sin-Yung Siu
- Department of Chemistry, Hong Kong Baptist University, Hong Kong 999077, China
| | - Chiu-Wing Chan
- Department of Chemistry, Hong Kong Baptist University, Hong Kong 999077, China
| | | | - Xuming Zhang
- Department of Applied Physics, Hong Kong Polytechnic University, Hong Kong 999077, China
| | | | - Kangning Ren
- Author to whom correspondence should be addressed: and
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58
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Chen Z, Liu P, Wang W, Cao X, Liu YX, Zhang YH, Ge M. Rapid Sulfate Formation via Uncatalyzed Autoxidation of Sulfur Dioxide in Aerosol Microdroplets. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:7637-7646. [PMID: 35638231 DOI: 10.1021/acs.est.2c00112] [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
Severe winter haze events in Beijing and North China Plain are characterized by rapid production of sulfate aerosols with unresolved mechanisms. Oxidation of SO2 by O2 in the absence of metal catalysts (uncatalyzed autoxidation) represents the most ubiquitous SO2 conversion pathway in the atmosphere. However, this reaction has long been regarded as too slow to be atmospherically meaningful. This traditional view was based on the kinetic studies conducted in bulk dilute solutions that mimic cloudwater but deviate from urban aerosols. Here, we directly measure the sulfate formation rate via uncatalyzed SO2 autoxidation in single (NH4)2SO4 microdroplets, by using an aerosol optical tweezer coupled with a cavity-enhanced Raman spectroscopy technique. We find that the aqueous reaction of uncatalyzed SO2 autoxidation is accelerated by two orders of magnitude at the high ionic strength (∼36 molal) conditions in the supersaturated aerosol water. Furthermore, at acidic conditions (pH 3.5-4.5), uncatalyzed autoxidation predominately occurs on droplet surface, with a reaction rate unconstrained by SO2 solubility. With these rate enhancements, we estimate that the uncatalyzed SO2 autoxidation in aerosols can produce sulfate at a rate up to 0.20 μg m-3 hr-1, under the winter air pollution condition in Beijing.
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Affiliation(s)
- 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
| | | | - Xue Cao
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Yu-Xin 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
| | - Maofa Ge
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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59
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Xing D, Meng Y, Yuan X, Jin S, Song X, Zare RN, Zhang X. Capture of Hydroxyl Radicals by Hydronium Cations in Water Microdroplets. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dong Xing
- Nankai University Chemistry 94 Weijin Rd 300071 Tianjin CHINA
| | - Yifan Meng
- Stanford University Department of Chemistry chemistry 380 Roth Way 94305 Stanford UNITED STATES
| | - Xu Yuan
- Nankai University Chemistry 94 Weijin Rd 300071 Tianjin CHINA
| | - Shuihui Jin
- Nankai University Chemistry 94 Weijin Rd 300071 Tianjin CHINA
| | - Xiaowei Song
- Stanford University Chemistry 380 Roth Way 94305 Stanford UNITED STATES
| | - Richard Neil Zare
- Stanford University Dept. of Chemistry Campus Way and Roth Way 94305-5080 Stanford UNITED STATES
| | - Xinxing Zhang
- Nankai University Chemistrty 94 Weijin Rd 300071 Tianjin CHINA
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60
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Li Z, Zeng H, Zhang X. Growth Rates of Hydrogen Microbubbles in Reacting Femtoliter Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6638-6646. [PMID: 35588476 DOI: 10.1021/acs.langmuir.2c00516] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chemical reactions in small droplets are extensively explored to accelerate the discovery of new materials and increase the efficiency and specificity in catalytic biphasic conversion and high-throughput analytics. In this work, we investigate the local rate of the gas-evolution reaction within femtoliter droplets immobilized on a solid surface. The growth rate of hydrogen microbubbles (≥500 nm in radius) produced from the reaction was measured online with high-resolution confocal microscopic images. The growth rate of bubbles was faster in smaller droplets and near the droplet rim in the same droplet. The results were consistent for both pure and binary reacting droplets and on substrates of different wettability. Our theoretical analysis based on diffusion, chemical reaction, and bubble growth predicted that the concentration of the reactant depended on the droplet size and the bubble location inside the droplet, in good agreement with experimental results. Our results reveal that the reaction rate may be spatially nonuniform in the reacting microdroplets. The findings may have implications for formulating the chemical properties and uses of these droplets.
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Affiliation(s)
- Zhengxin Li
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Xuehua Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
- Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, JM Burgers Center for Fluid Dynamics, Mesa+, Department of Science and Technology, University of Twente, Enschede 7522 NB, The Netherlands
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61
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Qiu L, Morato NM, Huang KH, Cooks RG. Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets. Front Chem 2022; 10:903774. [PMID: 35559217 PMCID: PMC9086510 DOI: 10.3389/fchem.2022.903774] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/11/2022] [Indexed: 12/20/2022] Open
Abstract
Spontaneous oxidation of compounds containing diverse X=Y moieties (e.g., sulfonamides, ketones, esters, sulfones) occurs readily in organic-solvent microdroplets. This surprising phenomenon is proposed to be driven by the generation of an intermediate species [M+H2O]+·: a covalent adduct of water radical cation (H2O+·) with the reactant molecule (M). The adduct is observed in the positive ion mass spectrum while its formation in the interfacial region of the microdroplet (i.e., at the air-droplet interface) is indicated by the strong dependence of the oxidation product formation on the spray distance (which reflects the droplet size and consequently the surface-to-volume ratio) and the solvent composition. Importantly, based on the screening of a ca. 21,000-compound library and the detailed consideration of six functional groups, the formation of a molecular adduct with the water radical cation is a significant route to ionization in positive ion mode electrospray, where it is favored in those compounds with X=Y moieties which lack basic groups. A set of model monofunctional systems was studied and in one case, benzyl benzoate, evidence was found for oxidation driven by hydroxyl radical adduct formation followed by protonation in addition to the dominant water radical cation addition process. Significant implications of molecular ionization by water radical cations for oxidation processes in atmospheric aerosols, analytical mass spectrometry and small-scale synthesis are noted.
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62
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Mehrgardi MA, Mofidfar M, Zare RN. Sprayed Water Microdroplets Are Able to Generate Hydrogen Peroxide Spontaneously. J Am Chem Soc 2022; 144:7606-7609. [PMID: 35451822 DOI: 10.1021/jacs.2c02890] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ultrapure N2 gas was bubbled through water, and the humidified output containing undetectable concentrations of ozone filled a closed chamber in which 18 MΩ-cm water was sprayed through a silica capillary to form microdroplets. Analysis of the collected microdroplets by NMR spectroscopy showed the presence of hydrogen peroxide at a concentration level ranging from 0.3 to 1.5 μM depending on the flow conditions. This was confirmed using a spectrofluorometric assay. We suggest that this finding establishes that when sprayed to form microdroplets, water has the ability to produce hydrogen peroxide by itself. When the N2 gas is replaced by compressed air or O2 gas, the concentration of hydrogen peroxide is found to increase, indicating that gas-surface interactions with O2 in aqueous microdroplets promote the formation of hydrogen peroxide.
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Affiliation(s)
- Masoud A Mehrgardi
- Department of Chemistry, Stanford University, Stanford, California 94305 United States.,Department of Chemistry, University of Isfahan, Isfahan 81746, Iran
| | - Mohammad Mofidfar
- Department of Chemistry, Stanford University, Stanford, California 94305 United States
| | - Richard N Zare
- Department of Chemistry, Stanford University, Stanford, California 94305 United States
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63
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Nguyen D, Nguyen SC. Revisiting the Effect of the Air-Water Interface of Ultrasonically Atomized Water Microdroplets on H 2O 2 Formation. J Phys Chem B 2022; 126:3180-3185. [PMID: 35439005 DOI: 10.1021/acs.jpcb.2c01310] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Studying chemical processes at the air-water interface is always challenging. A recent report claimed that H2O2 was formed spontaneously on the surface of condensed water microdroplets. However, a newer report concluded that the detected H2O2 in the previous report could originate in part from the water vapor source that involved ultrasonic atomization of liquid water. Here, this phenomenon is reinvestigated regarding the influence of ultrasonic cavitation, surface modification of droplets, and solutes in the bulk liquid on H2O2 production. When the droplet surfaces were modified by surfactants, H2O2 production did not change, whereas adding gases or inorganic compounds to the bulk solution caused significant changes in H2O2 production. These results confirm that H2O2 formation originates from cavitation in bulk solutions. It is concluded that the air-water interface of water microdroplets itself does not generate H2O2.
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Affiliation(s)
- Duy Nguyen
- Department of Chemistry and Biochemistry, University of California, Merced, California 95343, United States
| | - Son C Nguyen
- Department of Chemistry and Biochemistry, University of California, Merced, California 95343, United States
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64
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Sprayed water microdroplets containing dissolved pyridine spontaneously generate pyridyl anions. Proc Natl Acad Sci U S A 2022; 119:e2200991119. [PMID: 35286201 PMCID: PMC8944249 DOI: 10.1073/pnas.2200991119] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Water microdroplets can accelerate chemical reactions by orders of magnitude compared to the same reactions in bulk water and/or trigger spontaneous reactions that do not occur in bulk solution. Among the properties of water microdroplets, the unique redox ability resulting from the spontaneous dissociation of OH− into a released electron and •OH at the air–water interfaces is especially intriguing. At the air–water interface, OH− exhibits a strong reducing potential, and the resulting •OH is highly oxidative, making water microdroplets a unity of opposites. We report the reduction of pyridine into pyridyl anions (C5H5N−) and the oxidation of pyridine into hydroxypyridine, which extends what we know about the redox power of water microdroplets. The anion of pyridine, C5H5N−, has been thought to be short lived in the gas phase and was only previously observed indirectly. In the condensed phase, C5H5N− is known to be stabilized by solvation with other molecules. We provide in this study striking results for the formation of isolated C5H5N− from microdroplets of water containing dissolved pyridine observed in the negative ion mass spectrum. The gas-phase lifetime of C5H5N− is estimated to be at least 50 ms, which is much longer than previously thought. The generated C5H5N− captured CO2 molecules to form a stable (Py-CO2)− complex, further confirming the existence of C5H5N−. We propose that the high electric field at the air–water interface of a microdroplet helps OH− to transfer an electron to pyridine to form C5H5N− and the hydroxyl radical •OH. Oxidation products of the Py reacting with •OH are also observed in the mass spectrum recorded in positive mode, which further supports this mechanism. The present study pushes the limits of the reducing and oxidizing power of water microdroplets to a new level, emphasizing how different the behavior of microdroplets can be from bulk water. We also note that the easy formation of C5H5N− in water microdroplets presents a green chemistry way to synthesize value-added chemicals.
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65
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Chen W, Stolz S, Wegbecher V, Parakkattel D, Haeuser C, Oltra NS, Kishore RSK, Bond S, Bell C, Kopf R. The degradation of poloxamer 188 in buffered formulation conditions. AAPS OPEN 2022. [DOI: 10.1186/s41120-022-00055-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractPoloxamer 188 (P188) as a non-ionic surfactant is used in proteinaceous formulations to prevent protein adsorption to hydrophobic surfaces and unfolding at interfaces, preventing the formation of aggregates and particles. Its chemical intactness is crucial to the stability of drug products due to its protecting effects at interfaces. In order to identify and mitigate potential risks that might cause the degradation of P188 during the manufacturing process and storage, in the current work, the stability of P188 was investigated by forced degradation in buffered formulation conditions via oxidation and thermal stress conditions. The process of degradation was monitored through the dedicated liquid adsorption chromatography (LAC) with high sensitivity, and the degradants were characterized by high-resolution mass spectrometry. Results suggest that the vulnerability of P188 is largely related to the buffer conditions. Histidine promotes degradation in the presence of hydroxyl radicals but inhibits the degradation in the presence of H2O2 and alkyl radicals. In thermal stress conditions, histidine protects P188 from degradation at 40 °C, and activates its decay only at higher temperature, like 60 °C.
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66
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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: 39] [Impact Index Per Article: 19.5] [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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67
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Jiao X, He C, Yu H, He J, Wang C. Photo-generated hydroxyl radicals contribute to the formation of halogen radicals leading to ozone depletion on and within polar stratospheric clouds surface. CHEMOSPHERE 2022; 291:132816. [PMID: 34752833 DOI: 10.1016/j.chemosphere.2021.132816] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/02/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
Polar stratospheric clouds (PSCs), of which the surface is a dynamic liquid water layer and might consist of aqueous HNO3 and H2O2, is a well-known key meteorological condition contributing to the ozone hole in the polar stratosphere. PSCs has been considered to provide abundant surface for the heterogeneous reactions causing the formation of the Cl2 and HOCl, which are further photolyzed into Cl and ClO radicals leading to the ozone destruction. Here we demonstrated that the sunlight drives the massive and stable production of OH radicals in aqueous HNO3 and its main photo-induced byproduct HNO2. We also found that the photo-generated OH radicals in aqueous HNO3, HNO2 and H2O2 have the remarkable capability to react with the dissolved HCl, Cl- and Br- to form halogen radicals. In addition, we observed that the H2O2 can react with dissolved HCl and Br- in darkness to form and release Cl2 and Br2 gases, which could further be photolyzed into reactive halogen radicals whenever sunlight is available. All these findings suggest that, except for the well-known heterogeneous reactions, photochemical reactions involving the aqueous HNO3 and H2O2 on and within PSCs surface might constitute another important halogen activation pathway for ozone destruction. This study may shed deeper insights into the mechanism of halogen radicals resulting in ozone depletion in polar stratosphere.
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Affiliation(s)
- Xiaoyu Jiao
- College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan, 430074, China
| | - Congcong He
- College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan, 430074, China
| | - Huan Yu
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China
| | - Jun He
- Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China, Ningbo, 315100, China
| | - Chengjun Wang
- College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan, 430074, China.
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68
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Quantitative detection of hydrogen peroxide in rain, air, exhaled breath, and biological fluids by NMR spectroscopy. Proc Natl Acad Sci U S A 2022; 119:2121542119. [PMID: 35165177 PMCID: PMC8872725 DOI: 10.1073/pnas.2121542119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2022] [Indexed: 11/29/2022] Open
Abstract
Hydrogen peroxide (H2O2) plays a key role in environmental chemistry, biology, and medicine. H2O2 concentrations typically are 6 to 10 orders of magnitude lower than that of water, making its quantitative detection challenging. We demonstrate that optimized NMR spectroscopy allows direct, interference-free, quantitative measurements of H2O2 down to submicromolar levels in a wide range of fluids, ranging from exhaled breath and air condensate to rain, blood, urine, and saliva. NMR measurements confirm the previously reported spontaneous generation of H2O2 in microdroplets that form when condensing water vapor on a hydrophobic surface, which can interfere with atmospheric H2O2 measurements. Its antimicrobial activity and strong seasonal variation speculatively could be linked to the seasonality of respiratory viral diseases.
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69
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Chamberlayne CF, Zare RN. Microdroplets can act as electrochemical cells. J Chem Phys 2022; 156:054705. [PMID: 35135250 PMCID: PMC8824579 DOI: 10.1063/5.0078281] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 01/10/2022] [Indexed: 12/21/2022] Open
Abstract
A water microdroplet in air or oil typically possesses an electric double layer (EDL) from the preferential adsorption of surface-bound ions at the periphery. We present the calculations of the ion gradients within a microdroplet at equilibrium, including systems containing buffers and water autoionization. These ion gradients are used to calculate the potential energy stored within the microdroplet. We consider how this stored potential energy can be utilized to drive chemical reactions, much like an electrochemical cell. Effective voltages as high as 111 mV are found for microdroplets having a low surface charge density (0.01 ions per nm2). Two sources of potential energy are investigated: (1) the electrostatic energy of the EDL of the microdroplet and (2) shifts in other chemical equilibria coupled to the main reaction through the EDL. A particularly important example of the latter is water autoionization, wherein the reaction of interest causes a flattening of the [H+] gradient within the EDL, resulting in a net recombination of H+ and OH- throughout the microdroplet. Numerical calculations are performed using a continuum model consisting of a balance between the electromigration and diffusion of ions throughout the microdroplet. Our treatment accounts for the autoionization of water and any chemical equilibrium of buffers present. The results are presented for uncharged water microdroplets with low amounts of salts and simple buffers in them. However, the calculational method presented here can be applied to microdroplets of any net charge, composed of any solvent, containing ions of any valence, and containing complex mixtures of chemical equilibria.
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Affiliation(s)
| | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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70
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Basuri P, Shantha Kumar J, Unni K, Manna S, Pradeep T. Aggregation of molecules is controlled in microdroplets. Chem Commun (Camb) 2022; 58:12657-12660. [DOI: 10.1039/d2cc04587g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorescence microscopy reveals the control of aggregation and de-aggregation of molecules in microdroplets, which is strikingly different from that in the bulk.
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Affiliation(s)
- Pallab Basuri
- DST Unit of Nanoscience (DST UNS), Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Jenifer Shantha Kumar
- DST Unit of Nanoscience (DST UNS), Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Keerthana Unni
- DST Unit of Nanoscience (DST UNS), Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sujan Manna
- DST Unit of Nanoscience (DST UNS), Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Thalappil Pradeep
- DST Unit of Nanoscience (DST UNS), Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
- International Centre for Clean Water, Chennai, Tamil Nadu 600113, India
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71
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Xing D, Yuan X, Liang C, Jin T, Zhang S, Zhang X. Spontaneous oxidation of I − in water microdroplets and its atmospheric implications. Chem Commun (Camb) 2022; 58:12447-12450. [DOI: 10.1039/d2cc04288f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water microdroplets can oxidize I− into I˙, presenting a previously unknown source of I˙ and I2 in atmospheric water.
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Affiliation(s)
- Dong Xing
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), Shenzhen Research Institute, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin, 300071, China
| | - Xu Yuan
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), Shenzhen Research Institute, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin, 300071, China
| | - Chiyu Liang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), Shenzhen Research Institute, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin, 300071, China
| | - Tianyun Jin
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), Shenzhen Research Institute, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin, 300071, China
| | - Shuquan Zhang
- Integrated Chinese and Western Medicine Hospital, Tianjin University, Tianjin 300100, China
| | - Xinxing Zhang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), Shenzhen Research Institute, Frontiers Science Center for New Organic Matter, Nankai University, Tianjin, 300071, China
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72
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Davidse A, Zare RN. Effect of Relative Humidity in Air on the Transmission of Respiratory Viruses. MOLECULAR FRONTIERS JOURNAL 2021. [DOI: 10.1142/s252973252140006x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Viral respiratory infections have plagued mankind over its known history. Unfortunately, there has been a lack of meaningful progress in preventing the spread of viral respiratory infections globally. The central dogma appears to be that viruses are the villains. This framing focuses on a viral load balance (VLB) in the air. It follows that physical dilution through various means have been the primary focus of attempts to reduce the spread of infections. The problem of obesity provides a good example of how paradigm blindness can slow down progress in a field. Obesity has been framed as an energy balance disorder that blames overeating and lack of exercise for weight gain. Reframing obesity as a disorder of fat metabolism and storage caused by the quantity and quality of carbohydrates in the diet, referred to as the carbohydrate-insulin model (CIM), opened an alternative line of questioning with a testable hypothesis. Similarly, we postulate an alternative way to frame the spread of viral respiratory infections that would lead to new insights and potentially new ways to prevent infections. It has long been recognized that viral respiratory infections show a pronounced seasonal variation, referred to as seasonal forging, such that they increase in the winter but decrease or virtually disappear in the summer. In temperate regions, people spend over 90% of their time indoors. This is, therefore, where most respiratory infections are expected to occur. Evidence has been accumulating for decades on the strong correlation between variations in indoor relative humidity (RH) and variations in infection rates. Within a RH Goldilocks zone of 40%-60%, encapsulated viruses like influenza and SARS are optimally inactivated outside the infected host. Below 40% and above 80%, viruses can survive for extended periods in the air or on surfaces. This may explain in part the seasonality of infections as the indoor level of RH in winter is typically about 20% and above 40% in summer in temperate regions. However, the mechanism for the inactivation at midrange RH (in summer) is not well understood. This paper offers a hypothesis that could explain these observations. We have demonstrated that H2O2 and other reactive oxygen species (ROS) are formed spontaneously at the water-air interface of pure water microdroplets. Using only water and a nebulizing gas in the presence of oxygen, we have demonstrated the significant disinfectant potential of pure water microdroplets caused by the activity of H2O2 and other ROS. We postulate that spontaneous H2O2 and ROS formation in viruses containing exhaled microdroplets have a similar virucidal effect at mid-range RH. The droplet evaporation rate is sufficient to concentrate the solutes and provide enough time for reactions to occur at significantly higher rates than in bulk solutions. The concentration of H2O2 has also been shown to be positively correlated to RH. In addition, several other ROS/RNS may be present or formed through interactions with H2O2 that may act as even more effective virucide disinfectants to inactivate the virus. Below RH 40% evaporation happens too rapidly for these reactions to make an impact before the droplet is desiccated, and above RH 80% the solutes remain too diluted. Rapid inactivation of viruses at midrange RH may therefore play a greater role in preventing infections than physical dilution of virus load in the air through excessive mechanical ventilation. Similar to obesity, we suggest that a new paradigm that considers virus infectivity outside the host rather than the virus load balance in the air alone could greatly contribute to our understanding of respiratory infections. The proposed new “Relative Humidity Infectivity” RHI paradigm could explain the causal mechanisms underlying seasonal respiratory infections. This can point to better prevention strategies that avoid further distortion of our indoor environment and create conditions within which humans can thrive and be optimally protected. We need more focus on testing the various hypotheses and more data to determine which of the two paradigms will lead us in the right direction or how to use the best of both in an optimal combination. The stakes cannot be higher, and the potential for eradicating future viral respiratory pandemics with nature-based solutions may be right under our noses, literally.
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Affiliation(s)
- Adriaan Davidse
- PO Box 93167 Headon PO, Burlington, Ontario, L7M 4A3, Canada
| | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, CA 94305 USA
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73
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Kakeshpour T, Bax A. NMR characterization of H 2O 2 hydrogen exchange. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 333:107092. [PMID: 34700041 PMCID: PMC8639671 DOI: 10.1016/j.jmr.2021.107092] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/14/2021] [Accepted: 10/16/2021] [Indexed: 06/13/2023]
Abstract
Quantification of H2O2 concentration in aqueous solutions is of interest in many fields. It usually is based on indirect methods that rely on oxidation reactions that turn on/off fluorescent probes. Such methods can suffer from reaction incompleteness and interfering chemical species. We describe optimization of NMR detection that enables direct quantification of H2O2 down to the nanomolar range. Taking advantage of fast hydrogen exchange (HX) between H2O2 and water permits the use of very short interscan delays, greatly increasing sensitivity. The specific acid-, base- and water-catalyzed HX rates at 2 °C were measured to be 2.1 × 107, 6.1 × 109, and 1.4 × 10-1 M-1s-1, respectively, which result in a minimum HX rate at pH 6.2. Furthermore, the exchange is accelerated by general acid/base catalysis. MES and phosphate buffers catalyze HX strongest in their unprotonated forms. For imidazole, only the unprotonated form catalyzes HX, which contrasts with acetic acid where only the protonated state catalyzes exchange. Inorganic salts such as sodium chloride and azide have negligible effect on HX. We present optimal conditions for accurate measurement of H2O2 concentrations as low as 40 nM in aqueous samples in a few hours.
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Affiliation(s)
- Tayeb Kakeshpour
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
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74
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Musskopf NH, Gallo A, Zhang P, Petry J, Mishra H. The Air-Water Interface of Water Microdroplets Formed by Ultrasonication or Condensation Does Not Produce H 2O 2. J Phys Chem Lett 2021; 12:11422-11429. [PMID: 34792369 DOI: 10.1021/acs.jpclett.1c02953] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Recent reports on the production of hydrogen peroxide (H2O2) on the surface of condensed water microdroplets without the addition of catalysts or additives have sparked significant interest. The underlying mechanism is thought to be ultrahigh electric fields at the air-water interface; smaller droplets present larger interfacial areas and produce higher (detectable) H2O2 yields. To gain insights into this phenomenon, we performed condensation experiments and quantified H2O2 formation as a function of the vapor source. Specifically, we compared the H2O2 concentration in water microdroplets condensed from the vapor realized via (i) heating water in the range of 50-70 °C and (ii) ultrasonic humidification (as exploited in the original report). Experimental results revealed that the H2O2 level inside water microdroplets condensed via heating water was below our detection limit (≥0.25 μM), regardless of the droplet size or the substrate wettability. In contrast, water droplets condensed via ultrasonic humidification contained significantly higher (∼1 μM) H2O2 concentrations. We conclude that the ultrasonic humidifiers contribute to H2O2 production, not droplet interfacial effects.
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Affiliation(s)
- Nayara H Musskopf
- Interfacial Lab (iLab), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia
| | - Adair Gallo
- Interfacial Lab (iLab), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia
| | - Peng Zhang
- Interfacial Lab (iLab), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia
| | - Jeferson Petry
- Interfacial Lab (iLab), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia
| | - Himanshu Mishra
- Interfacial Lab (iLab), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), Thuwal 23955-6900, Saudi Arabia
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75
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Tang Y, Yang X, Li Y, Lu Y, Zhu D. Robust Micro-Nanostructured Superhydrophobic Surfaces for Long-Term Dropwise Condensation. NANO LETTERS 2021; 21:9824-9833. [PMID: 34472863 DOI: 10.1021/acs.nanolett.1c01584] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Design of hierarchical micromorphology represents an important strategy for developing functional surfaces but has yet to be achieved for promising long-term dropwise condensation. Herein, micropapillaes overlaid with nanograss were created to enhance dropwise condensation. By analyzing the nucleation and evolution of the condensate droplets, we elucidated that these hierarchical micro-nanostructures topologized tapered gaps, which produced upward pressure, to achieve spontaneous dislodging of condensate microdroplet out of gaps, and then to trigger microdroplet navigation before finally departing from the surface by coalescence-induced jumping. The high mobility of condensate delayed flooding and contributed to a very high heat transfer coefficient of 218 kW·m-2·K-1. Moreover, these micropapillaes served as forts that protected the nanograss from being destroyed, resulting in improved mechanical and chemical robustness. Our work proposed new examples of topology creation for long-term dropwise condensation heat transfer and shed light on application integration of such promising functional surfaces.
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Affiliation(s)
- Yu Tang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Xiaolong Yang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Yimin Li
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Yao Lu
- Department of Chemistry, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Di Zhu
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
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76
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Wang D, Tian Y, Jiang L. Abnormal Properties of Low-Dimensional Confined Water. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2100788. [PMID: 34176214 DOI: 10.1002/smll.202100788] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/25/2021] [Indexed: 06/13/2023]
Abstract
Water molecules confined to low-dimensional spaces exhibit unusual properties compared to bulk water. For example, the alternating hydrophilic and hydrophobic nanodomains on flat silicon wafer can induce the abnormal spreading of water (contact angles near 0°) which is caused by the 2D capillary effect. Hence, exploring the physicochemical properties of confined water from the nanoscale is of great value for understanding the challenges in material science and promoting the applications of nanomaterials in the fields of mass transport, nanofluidic designing, and fuel cell. The knowledge framework of confined water can also help to better understand the complex functions of the hydration layer of biomolecules, and even trace the origin of life. In this review, the physical properties, abnormal behaviors, and functions of the confined water are mainly summarized through several common low-dimensional water formats in the fields of solid/air-water interface, nanochannel confinement, and biological hydration layer. These researches indicate that the unusual behaviors of the confined water depend strongly on the confinement size and the interaction between the molecules and confining surface. These diverse properties of confined water open a new door to materials science and may play an important role in the future development of biology.
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Affiliation(s)
- Dianyu Wang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
| | - Ye Tian
- Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
- Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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Abstract
AbstractMist is generated by ultrasonic cavitation of water (Fisher Biograde, pH 5.5–6.5) at room temperature (20–25 °C) in open air with nearly constant temperature (22–25 °C) but varying relative humidity (RH; 24–52%) over the course of many months. Water droplets in the mist are initially about 7 μm in diameter at about 50% RH. They are collected, and the concentration of hydrogen peroxide (H2O2) is measured using commercial peroxide test strips and by bromothymol blue oxidation. The quantification method is based on the Fenton chemistry of dye degradation to determine the oxidation capacity of water samples that have been treated by ultrasonication. It is found that the hydrogen peroxide concentration varies nearly linearly with RH over the range studied, reaching a low of 2 parts per million (ppm) at 24% RH and a high of 6 ppm at 52% RH. Some possible public health implications concerning the transmission of respiratory viral infections are suggested for this threefold change in H2O2 concentration with RH.
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78
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Ruiz-López MF, Martins-Costa MTC, Francisco JS, Anglada JM. Tight electrostatic regulation of the OH production rate from the photolysis of hydrogen peroxide adsorbed on surfaces. Proc Natl Acad Sci U S A 2021; 118:e2106117118. [PMID: 34290148 PMCID: PMC8325346 DOI: 10.1073/pnas.2106117118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Recently, experimental and theoretical works have reported evidence indicating that photochemical processes may significantly be accelerated at heterogeneous interfaces, although a complete understanding of the phenomenon is still lacking. We have carried out a theoretical study of interface and surface effects on the photochemistry of hydrogen peroxide (H2O2) using high-level ab initio methods and a variety of models. Hydrogen peroxide is an important oxidant that decomposes in the presence of light, forming two OH radicals. This elementary photochemical process has broad interest and is used in many practical applications. Our calculations show that it can drastically be affected by heterogeneous interfaces. Thus, compared to gas phase, the photochemistry of H2O2 appears to be slowed on the surface of apolar or low-polar surfaces and, in contrast, hugely accelerated on ionic surfaces or the surface of aqueous electrolytes. We give particular attention to the case of the neat air-water interface. The calculated photolysis rate is similar to the gas phase, which stems from the compensation of two opposite effects, the blue shift of the n→σ* absorption band and the increase of the absorption intensity. Nevertheless, due to the high affinity of H2O2 for the air-water interface, the predicted OH production rate is up to five to six orders of magnitude larger. Overall, our results show that the photochemistry of H2O2 in heterogeneous environments is greatly modulated by the nature of the surface, and this finding opens interesting new perspectives for technological and biomedical applications, and possibly in various atmospheres.
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Affiliation(s)
- Manuel F Ruiz-López
- Laboratoire de Physique et Chimie Théoriques, CNRS UMR 7019, University of Lorraine, 54506 Vandoeuvre-lès-Nancy, France;
| | - Marilia T C Martins-Costa
- Laboratoire de Physique et Chimie Théoriques, CNRS UMR 7019, University of Lorraine, 54506 Vandoeuvre-lès-Nancy, France
| | - Joseph S Francisco
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104;
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Josep M Anglada
- Departament de Química Biològica, Institut de Química Avançada de Catalunya, Consejo Superior de Investigaciones Científicas, E-08034 Barcelona, Spain
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79
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Bredt AJ, Mendes de Oliveira D, Urbina AS, Slipchenko LV, Ben-Amotz D. Hydration and Seamless Integration of Hydrogen Peroxide in Water. J Phys Chem B 2021; 125:6986-6993. [PMID: 34133177 DOI: 10.1021/acs.jpcb.1c03107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Raman multivariate curve resolution is used to decompose the vibrational spectra of aqueous hydrogen peroxide (H2O2) into pure water, dilute H2O2, and concentrated H2O2 spectral components. The dilute spectra reveal four sub-bands in the OH stretch region, assigned to the OH stretch and Fermi resonant bend overtone of H2O2, and two nonequivalent OH groups on water molecules that donate a hydrogen bond to H2O2. At high concentrations, a spectral component resembling pure H2O2 emerges. Our results further demonstrate that H2O2 perturbs the structure of water significantly less than either methanol or sodium chloride of the same concentration, as evidenced by comparing the hydration-shell spectra of tert-butyl alcohol dissolved in the three aqueous solutions.
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Affiliation(s)
- Aria J Bredt
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | | | - Andres S Urbina
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lyudmila V Slipchenko
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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80
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Luo K, Chen H, Zare RN. Location of carbon-carbon double bonds in unsaturated lipids using microdroplet mass spectrometry. Analyst 2021; 146:2550-2558. [PMID: 33899059 DOI: 10.1039/d0an02396e] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An aqueous solution containing unsaturated fatty acids (100 μM) or lipids (50 μg mL-1) and chloroauric acid (HAuCl4, 10 μM) is electrosprayed (-4.5 kV for unsaturated fatty acids and +4.0 kV for lipids) from a 50 μm diameter capillary with N2 nebulizing gas (60 psi), and the resulting microdroplets enter a mass spectrometer with a flight distance of 10 mm for chemical analysis. The HAuCl4 oxidizes the C[double bond, length as m-dash]C double bond to cause the formation of an aldehyde group or a hydroxyl group on one side and a carboxyl group on the other (i.e., CHO-R-COOH or HO-R-COOH), allowing the location of the double bond to be identified. This approach was successfully applied to four unsaturated fatty acids [linoleic acid (LA), ricinoleic acid (RA), isooleic acid (IA), and nervonic acid (NA)] and two phospholipids [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and L-α-lysophosphatidylcholine (lysoPC)]. A mechanism for this transformation is proposed, which involves epoxidation of the double bond, followed by the formation of the final products. This method has the advantages of being simple and rapid, and requiring a small amount of analyte.
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Affiliation(s)
- Kai Luo
- Department of Chemistry, Fudan University, Jiangwan Campus, Shanghai 200438, China.
| | - Hao Chen
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Richard N Zare
- Department of Chemistry, Fudan University, Jiangwan Campus, Shanghai 200438, China.
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Zhang J, Coote ML, Ciampi S. Electrostatics and Electrochemistry: Mechanism and Scope of Charge-Transfer Reactions on the Surface of Tribocharged Insulators. J Am Chem Soc 2021; 143:3019-3032. [DOI: 10.1021/jacs.0c11006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jinyang Zhang
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
| | - Michelle L. Coote
- ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Simone Ciampi
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University, Bentley, Western Australia 6102, Australia
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