Kinetics of hypochlorous acid reactions with organic and chloride-containing tropospheric aerosol

Chlorine plays an important role in tropospheric oxidation processes, in both marine and continental environments. Although modeling studies have explored the importance of halogen chemistry, uncertainty remains in associated chemical mechanisms and fundamental kinetics parameters. Prior kinetics measurements of multiphase halogen recycling reactions have been largely performed with dilute, bulk solutions, leaving unexplored more realistic chemical systems which have high solute concentrations and are internally mixed with both halide and organic components. Here, we address the multiphase kinetics of gaseous HOCl using an aerosol flow tube and aerosol mass spectrometer to study its reactions with particulate chloride, using atmospherically relevant particle acidity, solute concentrations, and ionic strength. We also investigate the chemistry that results when biomass burning (BB) aerosol components and chloride are internally mixed. Using pH-buffered deliquesced particles, we show that the rate constant for reaction of dissolved HOCl with H+ and Cl- at high relative humidity (RH) (80-85%) is within a factor of two of the literature value for bulk phase conditions. However, at lower RH values (60-70%) where the particles are considerably more concentrated, the rate constant for chloride loss from the particles is an order of magnitude higher. For pure organic compounds commonly found in biomass burning (BB) aerosol, such as coniferaldehyde, salicylic acid and furfural, an increase in the aerosol chlorine content occurs with HOCl exposure, indicating the formation of organochlorine species. Together, these independent findings explain results for internally mixed aerosol particles with both chloride and BB components present where we observed behavior consistent with both chloride loss and organochlorine formation occurring simultaneously upon HOCl exposure. Our results indicate that chlorine recycling via HOCl uptake by chloride-containing particles will occur in the atmosphere efficiently over a wide range of RH conditions, even when reactive organic compounds are present in the same particles as chloride. Simultaneously, formation of organochlorine compounds, which are commonly toxic, is likely occurring when reactive organic components are present.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:25

Enthalten in:

Environmental science. Processes & impacts - 25(2023), 10 vom: 18. Okt., Seite 1645-1656

Sprache:

Englisch

Beteiligte Personen:

Jorga, Spiro D [VerfasserIn]
Liu, Tengyu [VerfasserIn]
Wang, Yutong [VerfasserIn]
Hassan, Sumaiya [VerfasserIn]
Huynh, Han [VerfasserIn]
Abbatt, Jonathan P D [VerfasserIn]

Links:

Volltext

Themen:

4R7X1O2820
712K4CDC10
Aerosols
Chlorides
Chlorine
Halogens
Hypochlorous Acid
Journal Article

Anmerkungen:

Date Completed 23.10.2023

Date Revised 23.10.2023

published: Electronic

Citation Status MEDLINE

doi:

10.1039/d3em00292f

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM362182140