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Heterogeneous production of Cl 2 from particulate chloride: Effects of composition and relative humidity
Author(s) -
Faxon Cameron B.,
Dhulipala Surya Venkatesh,
Allen David T.,
Hildebrandt Ruiz Lea
Publication year - 2018
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16204
Subject(s) - relative humidity , aerosol , chlorine , ozone , chemistry , chloride , atmospheric chemistry , troposphere , particulates , radical , environmental chemistry , composition (language) , chemical composition , inorganic chemistry , analytical chemistry (journal) , meteorology , organic chemistry , physics , linguistics , philosophy
Reactions initiated by chlorine atoms can enhance the formation of ozone (O 3 ) and secondary organic aerosol (SOA) in the troposphere. Environmental chamber experiments were conducted to quantify heterogeneous Cl 2 production from NH 4 Cl and NaCl particles exposed to O 3 and hydroxyl radicals (•OH). Observations are inconsistent with models of Cl 2 production resulting solely from surface‐mediated reactions of •OH and suggest that O 3 plays a significant role. The production of Cl 2 increased with relative humidity and decreased in the presence of SOA or nitric oxides (NO x ). Heterogeneous reactive uptake coefficients for the production of Cl 2 from O 3 on pure NH 4 Cl ( γO 3) averaged 1.4 ± 1.0 × 10 −3 . Cl 2 production was six times more efficient on NH 4 Cl aerosol than on NaCl aerosol. Model calculations under atmospheric conditions suggest this heterogeneous Cl 2 production could increase peak daily O 3 concentrations by over 10%. © 2018 American Institute of Chemical Engineers AIChE J , 64: 3151–3158, 2018