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Reaction Kinetics of Criegee Intermediates with Nitric Acid.
Jie-Ning Yang1,2, Kaito Takahashi1, Jim Jr-Min Lin1,2
1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
The Journal of Physical Chemistry. A
|August 31, 2022
Summary
Reactions between nitric acid (HNO₃) and Criegee intermediates (CIs) are very fast. These reactions may be significant in dry, polluted areas but less so in humid conditions or for overall HNO₃ removal due to low CI concentrations.
Area of Science:
- Atmospheric Chemistry
- Chemical Kinetics
Background:
- Criegee intermediates (CIs) are key species in atmospheric oxidation processes.
- Nitric acid (HNO₃) is a significant atmospheric pollutant.
Purpose of the Study:
- To investigate the reaction kinetics of HNO₃ with four distinct CIs.
- To compare experimental results with existing literature values and assess pressure dependence.
Main Methods:
- Flow tube experiments were conducted to measure reaction rate coefficients.
- Kinetic data were analyzed under varying pressure conditions (100-400 Torr).
Main Results:
- Extremely fast reaction rate coefficients were determined for HNO₃ with CH₂OO, (CH₃)₂COO, syn-MVKO, and anti-MACRO.
- The rate coefficient for CH₂OO + HNO₃ was found to be 3.6 times lower than previously reported.
- No significant pressure dependence was observed for the reactions of HNO₃ with CH₂OO and (CH₃)₂COO.
Conclusions:
- CI + HNO₃ reactions are rapid and potentially important in dry, polluted environments.
- These reactions are likely insignificant under high humidity.
- Due to low CI concentrations, these reactions may not be a major pathway for atmospheric HNO₃ removal.
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