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Formation of Chlorine in the Atmosphere by Reaction of Hypochlorous Acid with Seawater.

Imon MandalNatalia V KarimovaItai ZakaiR Benny Gerber
Published in: The journal of physical chemistry letters (2024)
The highly reactive dihalogens play a significant role in the oxidative chemistry of the troposphere. One of the main reservoirs of these halogens is hypohalous acids, HOX, which produce dihalogens in the presence of halides (Y - ), where X, Y = Cl, Br, I. These reactions occur in and on aerosol particles and seawater surfaces and have been studied experimentally and by field observations. However, the mechanisms of these atmospheric reactions are still unknown. Here, we establish the atomistic mechanism of HOCl + Cl - → Cl 2 + OH - at the surface of the water slab by performing ab initio molecular dynamics (AIMD) simulations. Main findings are (1) This reaction proceeds by halogen-bonded complexes of (HOCl)···(Cl - ) aq surrounded with the neighboring water molecules. (2) The halogen bonded (HOCl)···(Cl - ) aq complexes undergo charge transfer from Cl - to OH - to form transient Cl 2 at neutral pH. (3) The addition of a proton to one proximal water greatly facilitates the Cl 2 formation, which explains the enhanced rate at low pH.
Keyphrases
  • molecular dynamics
  • density functional theory
  • escherichia coli
  • cystic fibrosis
  • air pollution
  • particulate matter
  • electron transfer
  • tandem mass spectrometry