Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity

Abstract

We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including γ-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 γ-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 γ-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.

A molecular picture of surface interactions of organic compounds on prevalent indoor surfaces: limonene adsorption on SiO2

“…Furthermore, we calculated the surface concentration by combining volumetric measurements with C–H absorption band peak intensities for the adsorbed species as previously described (see Section S1†). 20,35 Fig. 1c shows time course measurements of limonene concentrations on SiO 2 .…”

A review of experimental techniques for aerosol hygroscopicity studies

“…Fourier transform infrared spectroscopy (FTIR), a vibrational absorption spectroscopy, has been widely employed in laboratory (Goodman et al, 2000;Eliason et al, 2003;Asad et al, 2004;Hung et al, 2005;Najera et al, 2009;Li et al, 2010;Tan et al, 2016;Tang et al, 2016b) and field work (Maria et al, 2002;Russell et al, 2011;Takahama et al, 2013Takahama et al, , 2019Kuzmiakova et al, 2016) to characterize the chemical composition of aerosol particles. It can also be used in aerosol hygroscopicity studies.…”

Modeling of aerosol property evolution during winter haze episodes over a megacity cluster in northern China: roles of regional transport and heterogeneous reactions of SO<sub>2</sub>

“…Heterogeneous chemistry on aerosol surfaces under high relative humidity has been considered a potential missing source of sulfate formation M. J. Tang et al, 2016).…”