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Cooke ME, Armstrong NC, Fankhauser AM, Chen Y, Lei Z, Zhang Y, Ledsky IR, Turpin BJ, Zhang Z, Gold A, McNeill VF, Surratt JD, Ault AP. Decreases in Epoxide-Driven Secondary Organic Aerosol Production under Highly Acidic Conditions: The Importance of Acid-Base Equilibria. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:10675-10684. [PMID: 38843196 DOI: 10.1021/acs.est.3c10851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2024]
Abstract
Isoprene has the highest atmospheric emissions of any nonmethane hydrocarbon, and isoprene epoxydiols (IEPOX) are well-established oxidation products and the primary contributors forming isoprene-derived secondary organic aerosol (SOA). Highly acidic particles (pH 0-3) widespread across the lower troposphere enable acid-driven multiphase chemistry of IEPOX, such as epoxide ring-opening reactions forming methyltetrol sulfates through nucleophilic attack of sulfate (SO42-). Herein, we systematically demonstrate an unexpected decrease in SOA formation from IEPOX on highly acidic particles (pH < 1). While IEPOX-SOA formation is commonly assumed to increase at low pH when more [H+] is available to protonate epoxides, we observe maximum SOA formation at pH 1 and less SOA formation at pH 0.0 and 0.4. This is attributed to limited availability of SO42- at pH values below the acid dissociation constant (pKa) of SO42- and bisulfate (HSO4-). The nucleophilicity of HSO4- is 100× lower than SO42-, decreasing SOA formation and shifting particulate products from low-volatility organosulfates to higher-volatility polyols. Current model parameterizations predicting SOA yields for IEPOX-SOA do not properly account for the SO42-/HSO4- equilibrium, leading to overpredictions of SOA formation at low pH. Accounting for this underexplored acidity-dependent behavior is critical for accurately predicting SOA concentrations and resolving SOA impacts on air quality.
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Affiliation(s)
- Madeline E Cooke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - N Cazimir Armstrong
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - Alison M Fankhauser
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yuzhi Chen
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - Ziying Lei
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yue Zhang
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - Isabel R Ledsky
- Department of Chemistry, Carleton College, Northfield, Minnesota 55057, United States
| | - Barbara J Turpin
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - Zhenfa Zhang
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - Avram Gold
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
| | - V Faye McNeill
- Department of Chemical Engineering, Columbia University, New York, New York 10027, United States
| | - Jason D Surratt
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27516, United States
- Department of Chemistry, College of Arts and Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Andrew P Ault
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Vielma T, Hefter G. Sulfate Protonation in Sodium Chloride and Sodium Perchlorate Media. J SOLUTION CHEM 2022. [DOI: 10.1007/s10953-022-01179-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractThe equilibrium (association) constant, KA, for the first protonation of the sulfate ion in aqueous solution: [H+(aq) + $${\text{SO}}_{4}^{2 - }$$
SO
4
2
-
(aq) ⇌ $${\text{HSO}}_{4}^{ - }$$
HSO
4
-
(aq)] has been measured at 298.15 K in NaCl and NaClO4 media using glass-electrode potentiometry at five ionic strengths in the range 0.5 ≤ I/(mol·dm−3) ≤ 5.0. The present KA values vary smoothly with I and are in good agreement with reliable literature data but indicate that the previously reported value of KA at I = 5 mol·dm−3 in NaClO4 media is in error.
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