Heterogeneous reactions of acetic acid with oxide surfaces: Effects of mineralogy and relative humidity

TitleHeterogeneous reactions of acetic acid with oxide surfaces: Effects of mineralogy and relative humidity
Publication TypeJournal Article
Year of Publication2016
AuthorsTang M.J, Larish W.A, Fang Y., Gankanda A., Grassian VH
JournalJournal of Physical Chemistry A
Volume120
Pagination5609-5616
Date Published2016/07
Type of ArticleArticle
ISBN Number1089-5639
Accession NumberWOS:000380590800022
Keywordsadsorbed water; calcium-carbonate; carboxylic-acids; cloud condensation; dust particles; gas-phase; ice nucleation; nitric-acid; uptake kinetics; volatile organic-compounds
Abstract

We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including gamma-Al2O3, SiO2, and CaO under a range of relative humidity conditions. Under dry conditions, the uptake of acetic acid leads to the formation of both acetate and molecularly adsorbed acetic acid on gamma-Al2O3 and CaO and only molecularly adsorbed acetic acid on SiO2. More importantly, under the conditions of this study, dimers are the major form for molecularly adsorbed acetic acid on all three particle surfaces investigated, even at low acetic acid pressures under which monomers are the dominant species in the gas phase. We have also determined saturation surface coverages for acetic acid adsorption on these three oxides under dry conditions as well as Langmuir adsorption constants in some cases. Kinetic analysis shows that the reaction rate of acetic acid increases by a factor of 3-5 for gamma-Al2O3 when relative humidity increases from 0% to 15%, whereas for SiO2 particles, acetic acid and water are found to compete for surface adsorption sites.

DOI10.1021/acs.jpca.6b05395
Short TitleJ. Phys. Chem. A
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