DOCSLIB.ORG

Lemon Phd Thesis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lemon Phd Thesis Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Christine Elizabeth Lemon, B.S. Graduate Program in Chemistry The Ohio State University 2012 Dissertation Committee: Heather C. Allen, Advisor Prabir K. Dutta Gerald S. Frankel Samuel D. Stout Barbara E. Wyslouzil Copyright by Christine E. Lemon 2012 Abstract Atmospheric corrosion is a costly problem. Accelerated laboratory tests, such as the salt fog chamber, have been created to predict corrosion of materials without the need to expose them over long periods of time outdoors. However, these accelerated tests often do not accurately reproduce the types and rates of corrosion found in field exposures. Silver exhibits this discrepancy and has been used in recent years in an attempt to correct the shortcomings of these accelerated tests. This study identifies Ag 2SO 3 and Ag 2SO 4 on field-exposed silver coupons. The presence of these species on field-exposed silver has been contested in the literature. Evidence suggests that Ag 2SO 3 is an intermediate step in the formation of Ag 2SO 4. Furthermore, the presence of alkali cations, such as Na +, determines the final oxidation + state of the sulfur species on silver. If Na is present, Ag 2SO 4 is the final state, whereas Ag 2SO 3 is not found in the presence of alkali cations. The identification of sulfite and/or sulfate on field-exposed samples suggests the need for further improvement of salt fog tests which do not currently include a sulfur source. In addition to proposing a mechanism for sulfate formation, this study also proposes a link between AgCl formation on inland samples and continental chloride sources. AgCl has been previously reported to form on silver exposed at nearly every location regardless of the proximity to marine sources. Studies have shown that ClNO 2, which is a reservoir species for chlorine, releases Cl radical when photolyzed. High levels ii of ClNO 2 have been reported at locations which are not near salt water sources. This study provides further evidence that AgCl is formed in every exposure location, with only one exception. The lack of correlation of cations, such as Na +, which are present in sea spray aerosols to Cl - on silver samples, is consistent with a non-salt water source of inland chloride. The abundance of ClNO 2 and therefore Cl radical at non-marine areas may be the cause of inland AgCl formation. iii Dedication This is dedicated to the people I love. iv Acknowledgments I would like to thank my advisor Dr. Heather Allen for her encouragement that I’ve needed during this process. I would also like to thank Dr. Gerald Frankel, Dr. Prabir Dutta, Dr. Barbara Wyslouzil, and Dr. Samuel Stout for being on my dissertation committee and giving me advice and suggestions on my thesis work. Acknowledgement must also go to the Mandaree Enterprise Corporation and the Office of the Secretary of Defense (OSD) who has funded me during the last five years; they made all of this a reality. Thanks also goes to the other people who have helped in various ways throughout my Ph.D., including my major collaborator, Huang Lin, who helped to teach me about corrosion; Joshua Hanna, who has helped my sanity and always answered my pestering emails; the other members of TCC (formerly the UCC); and Lisa Hommel for teaching me all about XPS. I would also like to thank Aaron Jubb, Chris Beekman, Corey Beck, Dominique Verreault, Ellen Adams, and Wei Hua, the long walks, company and great conversation throughout the years kept me from giving up long ago. I would also like to thank all of the Allen group members, past (those who laid the groundwork) and present (those who are left to continue forwards), for their camaraderie in this journey we all share. This thesis would not have been possible had it not been for Ryan. I have not always been a pleasure to be around during the dissertation process, but he has helped to v hold me up and push me forward. The love and support I feel at home has helped more than I can ever express and it will not soon be forgotten. Lastly and most significantly, I would like to thank my parents for always believing in me and being my cheerleaders. They always told me I could do anything I wanted to in life, and so, here I am. I literally would not be here without them. vi Vita March 23, 1985 ..............................................Born – Cincinnati, OH 2003................................................................Walnut Hills High School 2007................................................................B.S. Chemistry, University of Cincinnati 2007 to present ..............................................Graduate Teaching Associate, Department of Chemistry, The Ohio State University Publications C. E. Lemon, N. Goldberg, E. T. Klein-Riffle, J. K. Kronberg, B. S. Ault, “Matrix Isolation and Theoretical Study of the Photochemical Reactions of C 2H3Br and 1,2- C2H2Br 2 with CrO 2Cl 2.” Chemical Physics 326 (2-3), 349-355 (2006). Fields of Study Major Field: Chemistry vii Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments............................................................................................................... v Vita .................................................................................................................................... vii Publications ....................................................................................................................... vii Fields of Study .................................................................................................................. vii List of Tables .................................................................................................................... xii List of Figures .................................................................................................................. xiii List of Abbreviations & Symbols .................................................................................... xvi 1. Introduction ................................................................................................................. 1 1.1 Overview .............................................................................................................. 1 1.2 Corrosion .............................................................................................................. 2 1.3 Atmospheric Corrosion ........................................................................................ 4 1.4 Atmospheric Chemistry...................................................................................... 10 1.4.1 OH Radical.................................................................................................. 11 1.4.2 Ozone .......................................................................................................... 12 viii 1.4.3 Sulfur........................................................................................................... 13 1.4.4 Chlorine....................................................................................................... 16 1.5 Silver Corrosion as a Simplified Model of Metallic Corrosion ......................... 21 1.6 Problems and Goals ............................................................................................ 28 2. Experimental .............................................................................................................. 30 2.1 Sample Handling, Exposure, and Set-up ............................................................ 30 2.1.1 Field-Exposed Samples – New Hampshire................................................. 30 2.1.2 Field-Exposed Samples – Hawaii ............................................................... 33 2.1.3 Field-Exposed Samples – USA & Antarctica Single Measurements ......... 37 2.1.4 Accelerated Laboratory Samples ................................................................ 43 2.1.5 Sample Storage ........................................................................................... 46 2.2 X-ray Photoelectron Spectroscopy ..................................................................... 47 2.2.1 Theoretical Background .............................................................................. 47 2.2.2 Instrumentation ........................................................................................... 53 2.2.3 Data Analysis .............................................................................................. 55 3. Existence of Ag 2SO 3 and Ag 2SO 4 on Field-Exposed Silver ..................................... 60 3.1 Introduction ........................................................................................................ 60 3.2 Results ................................................................................................................ 61 3.2.1 New Hampshire .......................................................................................... 61 ix 3.2.2 Hawaii ......................................................................................................... 67 3.2.3 U.S.A. and Antarctica Single Measurements .............................................
Load more

Recommended publications
  • Nitrogen Oxides in the Troposphere – What Have We Learned from Satellite Measurements?
    Eur. Phys. J. Conferences 1, 149–156 (2009) © EDP Sciences, 2009 THE EUROPEAN DOI: 10.1140/epjconf/e2009-00916-9 PHYSICAL JOURNAL CONFERENCES Nitrogen oxides in the troposphere – What have we learned from satellite measurements? A. Richtera Institute of Environmental Physics, University of Bremen, 28359 Bremen, Germany Abstract. Nitrogen oxides are key species in the troposphere where they are linked to ozone formation and acid rain. The sources of nitrogen oxides are anthropogenic to large extend, mainly through combustion of fossil fuels. Satellite observations of NO2 provide global measurements of nitrogen oxides since summer 1995, and these data have been applied for many studies on the emission sources and strengths, the chemistry and the transport of NOx. In this paper, an overview will be given on satellite measurements of NO2, some examples of typical applications and an outlook on future prospects. 1 NOx in the troposphere Nitrogen oxides play several important roles in the atmosphere. In the stratosphere, they act as catalysts in ozone destruction reducing ozone levels and at the same time form reservoir substances with the halogen oxides thereby reducing their ozone depletion potential. In the troposphere, photolysis of NO2 is the only known route for ozone formation. As ozone is also rapidly destroyed by reaction with NO, nitrogen oxides (NOx =NO+NO2)and ozone are often in photochemical equilibrium in the troposphere. In the presence of HO2 or peroxy radicals (RO2), NO2 is reformed without destruction of an ozone molecule leading to accumulating of O3. Thereby, high levels of NOx together with volatile organic compounds and sufficient illumination lead to photochemical smog.
    [Show full text]
  • Toxicological Profile for Acetone Draft for Public Comment
    ACETONE 1 Toxicological Profile for Acetone Draft for Public Comment July 2021 ***DRAFT FOR PUBLIC COMMENT*** ACETONE ii DISCLAIMER Use of trade names is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry, the Public Health Service, or the U.S. Department of Health and Human Services. This information is distributed solely for the purpose of pre dissemination public comment under applicable information quality guidelines. It has not been formally disseminated by the Agency for Toxic Substances and Disease Registry. It does not represent and should not be construed to represent any agency determination or policy. ***DRAFT FOR PUBLIC COMMENT*** ACETONE iii FOREWORD This toxicological profile is prepared in accordance with guidelines developed by the Agency for Toxic Substances and Disease Registry (ATSDR) and the Environmental Protection Agency (EPA). The original guidelines were published in the Federal Register on April 17, 1987. Each profile will be revised and republished as necessary. The ATSDR toxicological profile succinctly characterizes the toxicologic and adverse health effects information for these toxic substances described therein. Each peer-reviewed profile identifies and reviews the key literature that describes a substance's toxicologic properties. Other pertinent literature is also presented, but is described in less detail than the key studies. The profile is not intended to be an exhaustive document; however, more comprehensive sources of specialty information are referenced. The focus of the profiles is on health and toxicologic information; therefore, each toxicological profile begins with a relevance to public health discussion which would allow a public health professional to make a real-time determination of whether the presence of a particular substance in the environment poses a potential threat to human health.
    [Show full text]
  • Global Modeling of the Nitrate Radical (NO3)Forpresentand Pre-Industrial Scenarios
    Atmospheric Research 164–165 (2015) 347–357 Contents lists available at ScienceDirect Atmospheric Research journal homepage: www.elsevier.com/locate/atmos Global modeling of the nitrate radical (NO3)forpresentand pre-industrial scenarios M.A.H. Khan a,M.C.Cookea,1, S.R. Utembe a,2, A.T. Archibald a,3,R.G.Derwentb,P.Xiaoa,C.J.Percivalc, M.E. Jenkin d, W.C. Morris a, D.E. Shallcross a,⁎ a Biogeochemistry Research Centre, School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK b rdscientific, Newbury, Berkshire, UK c The Centre for Atmospheric Science, The School of Earth, Atmospheric and Environmental Science, The University of Manchester, Simon Building, Brunswick Street, Manchester, M13 9PL, UK d Atmospheric Chemistry Services, Okehampton, Devon, EX20 4QB, UK article info abstract Article history: Increasing the complexity of the chemistry scheme in the global chemistry transport model STOCHEM to STOCHEM- Received 23 February 2015 CRI (Utembe et al., 2010) leads to an increase in NOx as well as ozone resulting in higher NO3 production over Received in revised form 26 May 2015 forested regions and regions impacted by anthropogenic emission. Peak NO3 is located over the continents near Accepted 8 June 2015 NO emission sources. NO is formed in the main by the reaction of NO with O ,andthesignificant losses of NO Available online 14 June 2015 x 3 2 3 3 are due to the photolysis and the reactions with NO and VOCs. Isoprene is an important biogenic VOC, and the possibility of HO recycling via isoprene chemistry and other mechanisms such as the reaction of RO with HO Keywords: x 2 2 STOCHEM-CRI has been investigated previously (Archibald et al., 2010a).
    [Show full text]
  • Butyraldehyde Casrn: 123-72-8 Unii: H21352682a
    BUTYRALDEHYDE CASRN: 123-72-8 UNII: H21352682A FULL RECORD DISPLAY Displays all fields in the record. For other data, click on the Table of Contents Human Health Effects: Human Toxicity Excerpts: /HUMAN EXPOSURE STUDIES/ Three Asian subjects who reported experiencing severe facial flushing in response to ethanol ingestion were subjects of patch testing to aliphatic alcohols and aldehydes. An aqueous suspension of 75% (v/v) of each alcohol and aldehyde was prepared and 25 uL was used to saturate ashless grade filter paper squares which were then placed on the forearm of each subject. Patches were covered with Parafilm and left in place for 5 minutes when the patches were removed and the area gently blotted. Sites showing erythema during the next 60 minutes were considered positive. All three subjects displayed positive responses to ethyl, propyl, butyl, and pentyl alcohols. Intense positive reactions, with variable amounts of edema, were observed for all the aldehydes tested (valeraldehyde as well as acetaldehyde, propionaldehyde, and butyraldehyde). [United Nations Environment Programme: Screening Information Data Sheets on n-Valeraldehyde (110-62-3) (October 2005) Available from, as of January 15, 2009: http://www.chem.unep.ch/irptc/sids/OECDSIDS/sidspub.html] **PEER REVIEWED** [United Nations Environment Programme: Screening Information Data Sheets on n­Valeraldehyde (110­62­3) (October 2005) Available from, as of January 15, 2009: http://www.chem.unep.ch/irptc/sids/OECDSIDS/sidspub.html] **PEER REVIEWED** /SIGNS AND SYMPTOMS/ May act as irritant, /SRP: CNS depressant/ ...[Budavari, S. (ed.). The Merck Index - Encyclopedia of Chemicals, Drugs and Biologicals. Rahway, NJ: Merck and Co., Inc., 1989., p.
    [Show full text]
  • SROC Annex V
    Annex V Major Chemical Formulae and Nomenclature This annex presents the formulae and nomenclature for halogen-containing species and other species that are referred to in this report (Annex V.1). The nomenclature for refrigerants and refrigerant blends is given in Annex V.2. V.1 Substances by Groupings V.1.1 Halogen-Containing Species V.1.1.1 Inorganic Halogen-Containing Species Atomic chlorine Cl Atomic bromine Br Molecular chlorine Cl2 Molecular bromine Br2 Chlorine monoxide ClO Bromine monoxide BrO Chlorine radicals ClOx Bromine radicals BrOx Chloroperoxy radical ClOO Bromine nitrate BrONO2, BrNO3 Dichlorine peroxide (ClO dimer) (ClO)2, Cl2O2 Potassium bromide KBr Hydrogen chloride (Hydrochloric acid) HCl Inorganic chlorine Cly Antimony pentachloride SbCl5 Atomic fluorine F Molecular fluorine F2 Atomic iodine I Hydrogen fluoride (Hydrofluoric acid) HF Molecular iodine I2 Sulphur hexafluoride SF6 Nitrogen trifluoride NF3 IPCC Boek (dik).indb 467 15-08-2005 10:57:13 468 IPCC/TEAP Special Report: Safeguarding the Ozone Layer and the Global Climate System V.1.1.2 Halocarbons For each halocarbon the following information is given in columns: • Chemical compound [Number of isomers]1 (or common name) • Chemical formula • CAS number2 • Chemical name (or alternative name) V.1.1.2.1 Chlorofluorocarbons (CFCs) CFC-11 CCl3F 75-69-4 Trichlorofluoromethane CFC-12 CCl2F2 75-71-8 Dichlorodifluoromethane CFC-13 CClF3 75-72-9 Chlorotrifluoromethane CFC-113 [2] C2Cl3F3 Trichlorotrifluoroethane CCl FCClF 76-13-1 CFC-113 2 2 1,1,2-Trichloro-1,2,2-trifluoroethane
    [Show full text]
  • Guidance on Information Requirements and Chemical Safety Assessment Chapter R.6: Qsars and Grouping of Chemicals
    Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals May 2008 Guidance for the implementation of REACH LEGAL NOTICE This document contains guidance on REACH explaining the REACH obligations and how to fulfil them. However, users are reminded that the text of the REACH regulation is the only authentic legal reference and that the information in this document does not constitute legal advice. The European Chemicals Agency does not accept any liability with regard to the contents of this document. © European Chemicals Agency, 2008 Reproduction is authorised provided the source is acknowledged. 2 CHAPTER R.6 – QSARS AND GROUPING OF CHEMICALS PREFACE This document describes the information requirements under REACH with regard to substance properties, exposure, use and risk management measures, and the chemical safety assessment. It is part of a series of guidance documents that are aimed to help all stakeholders with their preparation for fulfilling their obligations under the REACH regulation. These documents cover detailed guidance for a range of essential REACH processes as well as for some specific scientific and/or technical methods that industry or authorities need to make use of under REACH. The guidance documents were drafted and discussed within the REACH Implementation Projects (RIPs) led by the European Commission services, involving stakeholders from Member States, industry and non-governmental organisations. These guidance documents can be obtained via the website of
    [Show full text]
  • ECG Environmental Briefs ECGEB No
    ECG Environmental Briefs ECGEB No. 3 Atmospheric chemistry at night Atmospheric chemistry is driven, in large part, by sunlight. Air pollution, for example, and especially the formation of ground-level ozone, is a day-time phenomenon. So what happens between the hours of sunset and sunrise? This Brief examines the night-time chemistry of the HO2 + NO OH + NO2 [R3] troposphere (the lower-most atmospheric layer from the 3 NO2 + light (λ < 420nm) NO + O( P) [R4] surface up to 12 km). Atmospheric chemistry is 3 predominantly oxidation chemistry, and the vast majority of O( P) + O2 O3 [R5] gases from emission sources are oxidised within the Night-time tropospheric chemistry troposphere. The unique aspects of atmospheric oxidation chemistry at night are best appreciated by first reviewing the It is an obvious statement: there is no sunlight at night. day-time chemistry. Therefore the night-time concentration of OH is (almost) zero. Instead, another oxidant, the nitrate radical, NO , is Day-time tropospheric chemistry 3 generated at night by the reaction of NO2 with ozone. NO3 The first Environmental Brief (1) considered in detail the radicals further react with NO2 to establish a chemical photolysis of ozone at near-ultraviolet wavelengths to equilibrium with N2O5. generate electronically excited oxygen atoms: NO2 + O3 NO3 + O2 [R6] 1 O3 + light (λ < 340nm) O( D) + O2 [R1] NO3 + NO2 ⇌ N2O5 [R7] Reaction R1 is a key process in tropospheric chemistry Reaction R6 happens during the day too. However, NO3 is 1 because the O( D) atom has sufficient excitation energy to quickly photolysed by daylight, and therefore NO3 and its react with water vapour to produce hydroxyl radicals: equilibrium partner N2O5 are both heavily suppressed during 1 the day.
    [Show full text]
  • Questions for the Record Public Meeting on the Petition Regarding Additive Organohalogen Flame Retardants U.S
    Questions for the Record Public Meeting on the Petition Regarding Additive Organohalogen Flame Retardants U.S. Consumer Product Safety Commission Bethesda, MD Part 3 of 4: This file contains the questions and responses for presenters 25 through 27. Panel Presenter Affiliation Notes Panel 1 1 Linda Birnbaum, Ph.D. NIEHS/National Toxicology Program Panel 2 2 William Wallace Consumers Union 3 Eve Gartner Earthjustice Northeast Office 4 Simona Balan, Ph.D. Green Science Policy Institute Joint response 5 Arlene Blum, Ph.D. 6 Miriam Diamond, Ph.D. University of Toronto Panel 3 7 Jennifer Lowery, MD, FAAP American Academy of Pediatrics 8 Patrick Morrison International Association of Fire Fighters 9 Luis Torres League of United Latin American Citizens 10 Maureen Swanson, MPA Learning Disabilities Association of America 11 Daniel Penchina The Raben Group/Breast Cancer Fund American Chemistry Council/North American Panel 4 12 Robert Simon Flame Retardant Alliance 13 Michael Walls American Chemistry Council No response 14 Matthew S. Blais, Ph.D. Southwest Research Institute 15 Thomas Osimitz, Ph.D. Science Strategies Information Technology Industry Council and the 16 Chris Cleet, QEP Consumer Technology Association 17 Timothy Reilly Clariant Corporation Panel 5 18 Rachel Weintraub Consumer Federation of America 19 Katie Huffling, RN, MS, CNM Alliance of Nurses for Family Environments 20 Kathleen A. Curtis, LPN Clean and Healthy New York Ecology Center/American Sustainable Business 21 Jeff Gearhart Council 22 Bryan McGannon American Sustainable Business Council Panel 6 23 Vytenis Babrauskas, Ph.D. Fire Science and Technology, Inc. 24 Donald Lucas, Ph.D. Lawrence Berkeley National Laboratory 25 Jennifer Sass, Ph.D.
    [Show full text]
  • Ozone Depletion, Greenhouse Gases, and Climate Change
    DOCUMENT RESUME ED 324 229 SE 051 620 TITLE Ozone Depletion, Greenhouse Gaaes, and Climate Change. Proceedings of a Joint Symposium by theBoard on Atmospheric Sciences and Climate andthe Committee on Global Change, National ResearchCouncil (Washington, D.C., March 23, 1988). INSTITUTION National Academy of Sciences - National Research Council, Washington, D.C. SPONS AGENCY National Science Foundation, Washington, D.C. REPORT NO ISBN-0-309-03945-2 PUB DATE 90 NOTE 137p. AVAILABLE FROMNational Academy of Scences, National AcademyPress, 2101 Constitution Avenue, NW, Washington, DC 20418 ($20.00). PUB TYPE Collected Works Conference Proceedings (021) EDRS PRICE MF01 Plus Postage. PC Not Available from EDRS. DESCRIPTORS Air Pollution; *Climate; *Conservation(Environment); Depleted Resources; Earth Science; Ecology; *Environmental Education; *Environmental Influences; Global Approach; *Natural Resources; Science Education; Thermal Environment; World Affairs; World Problems IDENTIFIERS *Global Climate Change ABSTRACT The motivation for the organization of thissymposium was the accumulation of evidence from manysources, both short- and longterm,_that the global climate is in a state of change. Data which defy integrated explanation including temperature, ozone, methane, precipitation and other climate-related trendshave presented troubling problems for atmospheric sciencesince the 1980's. Ten papers from this symposium are presentedhere: (1) "Global Change and the Changing Atmosphere"(William C. Clark); (2) "Stratospheric Ozone Depletion: Global Processes"(Daniel L. Albritton); (3) "Stratospheric Czone Depletion: AntarcticProcesses" (Robert T. Watson); (4) "The Role of Halocarbons in Stratospheric Ozone Depletion" (F. Sherwood Rowland);(5) "Heterogenous Chemical Processes in Ozone Depletion" (Mario J. Molina);(6) "Free Radicals in the Earth's Atmosphere: Measurement andInterpretation" (James G. Anderson); (7) "Theoretical Projections of StratosphericChange Due to Increasing Greenhouse Gases and Changing OzoneConcentrations" (Jerry D.
    [Show full text]
  • Ambient Air Pollution by Polycyclic Aromatic Hydrocarbons (PAH)
    Ambient Air Pollution by Polycyclic Aromatic Hydrocarbons (PAH) Position Paper Annexes July 27th 2001 Prepared by the Working Group On Polycyclic Aromatic Hydrocarbons PAH Position Paper Annexes July 27th 2001 i PAH Position Paper Annexes July 27th 2001 Contents ANNEX 1...............................................................................................................................................................1 MEMBERSHIP OF THE WORKING GROUP .............................................................................................................1 ANNEX 2...............................................................................................................................................................3 Tables and Figures 3 Table 1: Physical Properties and Structures of Selected PAH 4 Table 2: Details of carcinogenic groups and measurement lists of PAH 9 Table 3: Review of Legislation or Guidance intended to limit ambient air concentrations of PAH. 10 Table 4: Emissions estimates from European countries - Anthropogenic emissions of PAH (tonnes/year) in the ECE region 12 Table 5: Summary of recent (not older than 1990) typical European PAH- and B(a)P concentrations in ng/m3 as annual mean value. 14 Table 6: Summary of benzo[a]pyrene Emissions in the UK 1990-2010 16 Table 7: Current network designs at national level (end-1999) 17 Table 8: PAH sampling and analysis methods used in several European countries. 19 Table 9: BaP collected as vapour phase in European investigations: percent relative to total (vapour
    [Show full text]
  • Reaction Mechanisms Underlying Unfunctionalized Alkyl Nitrate Hydrolysis in Aqueous Aerosols Fatemeh Keshavarz,* Joel A
    http://pubs.acs.org/journal/aesccq Article Reaction Mechanisms Underlying Unfunctionalized Alkyl Nitrate Hydrolysis in Aqueous Aerosols Fatemeh Keshavarz,* Joel A. Thornton, Hanna Vehkamaki,̈ and Theo Kurteń Cite This: ACS Earth Space Chem. 2021, 5, 210−225 Read Online ACCESS Metrics & More Article Recommendations *sı Supporting Information ABSTRACT: Alkyl nitrates (ANs) are both sinks and sources of nitrogen oxide radicals (NOx = NO + NO2) in the atmosphere. Their reactions affect both the nitrogen cycle and ozone formation and therefore air quality and climate. ANs can be emitted to the atmosphere or produced in the gas phase. In either case, they can partition into aqueous aerosols, where they might undergo hydrolysis, producing highly soluble nitrate products, and act as a permanent sink for NOx. The kinetics of AN hydrolysis partly determines the extent of AN contribution to the nitrogen cycle. However, kinetics of many ANs in various aerosols is unknown, and there are conflicting arguments about the effect of acidity and basicity on the hydrolysis process. Using computational methods, this study proposes a mechanism for the reactions of methyl, ethyl, propyl, and butyl nitrates with OH− (hydroxyl ion; basic hydrolysis), water + (neutral hydrolysis), and H3O (hydronium ion; acidic hydrolysis). Using quantum chemical data and transition state theory, we follow the effect of pH on the contribution of the basic, neutral, and acidic hydrolysis channels, and the rate coefficients of AN hydrolysis over a wide range of pH. Our results show that basic hydrolysis (i.e., AN reaction with OH−) is the most kinetically and thermodynamically favorable reaction among our evaluated reaction schemes.
    [Show full text]
  • Significant Impact of Heterogeneous Reactions of Reactive Chlorine Species on Summertime Atmospheric Ozone and Free-Radical Form
    Science of the Total Environment 693 (2019) 133580 Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Significant impact of heterogeneous reactions of reactive chlorine species on summertime atmospheric ozone and free-radical formation in north China Xionghui Qiu a,b,QiYingc,⁎, Shuxiao Wang a,b,⁎⁎, Lei Duan a,b, Yuhang Wang d,KedingLue,PengWangf, Jia Xing a,b, Mei Zheng g,MinjiangZhaoa,b, Haotian Zheng a,b, Yuanhang Zhang e,JimingHaoa,b a State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China b State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China c Zachry Department of Civil Engineering, Texas A&M University, College Station, TX, United States d School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States e State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University,Beijing,China f Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, 999077, Hong Kong, China g SKL-ESPC and BIC-ESAT, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China HIGHLIGHTS GRAPHICAL ABSTRACT • This work represents the first high reso- lution regional modeling to quantify the impact of chlorine chemistry on the ox- idation capacity in a polluted urban at- mosphere. • These heterogeneous reactions of reac- tive chlorine species increased the O3, OH, HO2 and RO2 concentrations signifi- cantly for some regions in the Beijing- Tianjin-Hebei (BTH) area.
    [Show full text]