Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K
International audience The uptake and reaction of HOBr with frozen salt surfaces of variable NaCl / NaBr composition and temperature were investigated with a coated wall flow tube reactor coupled to a mass spectrometer for gas-phase analysis. HOBr is efficiently taken up onto the frozen surfaces at...
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ftccsdartic:oai:HAL:hal-00300822v1 2023-11-12T04:14:01+01:00 Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K Adams, J. W. Holmes, N. S. Crowley, J. N. Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft 2002-01-22 https://hal.science/hal-00300822 https://hal.science/hal-00300822/document https://hal.science/hal-00300822/file/acpd-2-109-2002.pdf en eng HAL CCSD European Geosciences Union hal-00300822 https://hal.science/hal-00300822 https://hal.science/hal-00300822/document https://hal.science/hal-00300822/file/acpd-2-109-2002.pdf info:eu-repo/semantics/OpenAccess ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00300822 Atmospheric Chemistry and Physics Discussions, 2002, 2 (1), pp.109-145 [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere info:eu-repo/semantics/article Journal articles 2002 ftccsdartic 2023-10-21T23:14:02Z International audience The uptake and reaction of HOBr with frozen salt surfaces of variable NaCl / NaBr composition and temperature were investigated with a coated wall flow tube reactor coupled to a mass spectrometer for gas-phase analysis. HOBr is efficiently taken up onto the frozen surfaces at temperatures between 253 and 233 K where it reacts to form the di-halogens BrCl and Br 2 , which are subsequently released into the gas-phase. The uptake coefficient for HOBr reacting with a frozen, mixed salt surface of similar composition to sea-spray was approx. 10 -2 . The relative concentration of BrCl and Br 2 released to the gas-phase was found to be strongly dependent on the ratio of Cl - to Br - in the solution prior to freezing / drying. For a mixed salt surface of similar composition to sea-spray the major product at low conversion of surface reactants (i.e. Br - and Cl - ) was Br 2 . Variation of the pH of the NaCl / NaBr solution used to prepare the frozen surfaces was found to have no significant influence on the results. The observations are explained in terms of initial formation of BrCl in a surface reaction of HOBr with Cl - , and conversion of BrCl to Br 2 via reaction of surface Br - . Experiments on the uptake and reaction of BrCl with frozen NaCl / NaBr solutions served to confirm this hypothesis. The kinetics and products of the interactions of BrCl, Br 2 and Cl 2 with frozen salt surfaces were also investigated, and lower limits to the uptake coefficients of > 0.034, >0.025 and >0.028 respectively, were obtained. The uptake and reaction of HOBr on dry salt surfaces was also investigated and the results closely resemble those obtained for frozen surfaces. During the course of this study the gas diffusion coefficients of HOBr in He and H 2 O were also measured as (273 ± 1) Torr cm 2 s -1 and (51 ± 1) Torr cm 2 s -1 , respectively, at 255 K. The implications of these results for modelling the chemistry of the Arctic boundary layer in springtime are discussed. Article in Journal/Newspaper Arctic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Arctic |
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Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
spellingShingle |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere Adams, J. W. Holmes, N. S. Crowley, J. N. Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
topic_facet |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere |
description |
International audience The uptake and reaction of HOBr with frozen salt surfaces of variable NaCl / NaBr composition and temperature were investigated with a coated wall flow tube reactor coupled to a mass spectrometer for gas-phase analysis. HOBr is efficiently taken up onto the frozen surfaces at temperatures between 253 and 233 K where it reacts to form the di-halogens BrCl and Br 2 , which are subsequently released into the gas-phase. The uptake coefficient for HOBr reacting with a frozen, mixed salt surface of similar composition to sea-spray was approx. 10 -2 . The relative concentration of BrCl and Br 2 released to the gas-phase was found to be strongly dependent on the ratio of Cl - to Br - in the solution prior to freezing / drying. For a mixed salt surface of similar composition to sea-spray the major product at low conversion of surface reactants (i.e. Br - and Cl - ) was Br 2 . Variation of the pH of the NaCl / NaBr solution used to prepare the frozen surfaces was found to have no significant influence on the results. The observations are explained in terms of initial formation of BrCl in a surface reaction of HOBr with Cl - , and conversion of BrCl to Br 2 via reaction of surface Br - . Experiments on the uptake and reaction of BrCl with frozen NaCl / NaBr solutions served to confirm this hypothesis. The kinetics and products of the interactions of BrCl, Br 2 and Cl 2 with frozen salt surfaces were also investigated, and lower limits to the uptake coefficients of > 0.034, >0.025 and >0.028 respectively, were obtained. The uptake and reaction of HOBr on dry salt surfaces was also investigated and the results closely resemble those obtained for frozen surfaces. During the course of this study the gas diffusion coefficients of HOBr in He and H 2 O were also measured as (273 ± 1) Torr cm 2 s -1 and (51 ± 1) Torr cm 2 s -1 , respectively, at 255 K. The implications of these results for modelling the chemistry of the Arctic boundary layer in springtime are discussed. |
author2 |
Max-Planck-Institut für Chemie (MPIC) Max-Planck-Gesellschaft |
format |
Article in Journal/Newspaper |
author |
Adams, J. W. Holmes, N. S. Crowley, J. N. |
author_facet |
Adams, J. W. Holmes, N. S. Crowley, J. N. |
author_sort |
Adams, J. W. |
title |
Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
title_short |
Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
title_full |
Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
title_fullStr |
Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
title_full_unstemmed |
Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233K |
title_sort |
uptake and reaction of hobr on frozen and dry nacl/nabr surfaces between 253 and 233k |
publisher |
HAL CCSD |
publishDate |
2002 |
url |
https://hal.science/hal-00300822 https://hal.science/hal-00300822/document https://hal.science/hal-00300822/file/acpd-2-109-2002.pdf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
ISSN: 1680-7367 EISSN: 1680-7375 Atmospheric Chemistry and Physics Discussions https://hal.science/hal-00300822 Atmospheric Chemistry and Physics Discussions, 2002, 2 (1), pp.109-145 |
op_relation |
hal-00300822 https://hal.science/hal-00300822 https://hal.science/hal-00300822/document https://hal.science/hal-00300822/file/acpd-2-109-2002.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782331762022547456 |