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N2O5 reactive uptake on aqueous sulfuric acid solutions coated with branched and straight-chain insoluble organic surfactants

TitleN2O5 reactive uptake on aqueous sulfuric acid solutions coated with branched and straight-chain insoluble organic surfactants
Publication TypeJournal Article
Year of Publication2008
AuthorsCosman, LM, Knopf, DA, Bertram, AK
JournalJournal of Physical Chemistry A
Volume112
Pagination2386-2396
Date PublishedMar
ISBN Number1089-5639
Abstract

A flow reactor coupled to a chemical ionization mass spectrometer was used to study the reactive uptake coefficients at 273 K of N2O5 on aqueous 60 wt % sulfuric acid solutions coated with insoluble organic monolayers. Both straight-chain surfactants (1-hexadecanol, l-octadecanol, and stearic acid) and a branched surfactant (phytanic acid) were studied. The reactive uptake coefficient decreased dramatically for straight-chain surfactants. The decrease ranged from a factor of 17 to a factor of 61 depending on the type of straight-chain surfactant. In contrast to the straight-chain data, the presence of phytanic acid did not have a significant effect on the N2O5 reactive uptake coefficient (the decrease was less than the uncertainty in the data) compared to the uncoated solution. In addition to measuring the reactive uptake coefficients, we also investigated the relationship between properties of the monolayers and the reactive uptake coefficients. The. reactive uptake coefficients measured on aqueous sulfuric acid subphases showed a relationship to the surface area occupied by the surfactant molecules. However, data obtained with other subphases did not overlap with this trend.

URL<Go to ISI>://000253946100027