%0 Journal Article
%A Romanías, Manolis N.
%A Ourrad, Habib
%A Thévenet, Frédéric
%A Riffault, Véronique
%D 2016
%T Investigating the Heterogeneous Interaction of VOCs
with Natural Atmospheric Particles: Adsorption of Limonene and Toluene
on Saharan Mineral Dusts
%U https://acs.figshare.com/articles/journal_contribution/Investigating_the_Heterogeneous_Interaction_of_VOCs_with_Natural_Atmospheric_Particles_Adsorption_of_Limonene_and_Toluene_on_Saharan_Mineral_Dusts/2299294
%R 10.1021/acs.jpca.5b10323.s001
%2 https://acs.figshare.com/ndownloader/files/3936856
%K path transmission Fourier
%K FTIR
%K coverage measurements
%K N 2 sorption measurements
%K XRD
%K XRF
%K SiO 2 content
%K VOC
%K 100 μ m
%K Natural Atmospheric Particles
%K DRIFTS
%K temperature 293 K
%K SIFT
%K adsorption
%K Saharan Mineral DustsThe
%K limonene
%K SiO 2
%K mineral dust samples
%X The
heterogeneous interaction of limonene and toluene with Saharan
dusts was investigated under dark conditions, pressure of 1 atm, and
temperature 293 K. The mineral dust samples were collected from six
different regions along the Sahara desert, extending from Tunisia
to the western Atlantic coastal areas of Morocco, and experiments
were carried out with the smallest sieved fractions, that is, inferior
to 100 μm. N2 sorption measurements, granulometric
analysis, and X-ray fluorescence and diffraction (XRF and XRD) measurements
were conducted to determine the physicochemical properties of the
particles. The chemical characterization showed that dust originating
from mideastern Sahara has a significantly higher SiO2 content
(∼82%) than dust collected from the western coastal regions
where the SiO2 relative abundance was ∼50%. A novel
experimental setup combining diffuse reflectance infrared Fourier
transform spectroscopy (DRIFTS), selected-ion flow-tube mass spectrometry
(SIFT–MS), and long path transmission Fourier transform infrared
spectroscopy (FTIR) allowed us to follow both the adsorbed and gas
phases. The kinetic adsorption/desorption measurements were performed
using purified dry air as bath gas, exposing each dust surface to
10 ppm of the selective volatile organic compound (VOC). The adsorption
of limonene was independent of the SiO2 content, given
the experimental uncertainties, and the coverage measurements ranged
between (10 and 18) × 1013 molecules cm–2. Experimental results suggest that other metal oxides that could
possibly influence dust acidity may enhance the adsorption of limonene.
On the contrary, in the case of toluene, the adsorption capacities
of the Saharan samples increased with decreasing SiO2 content;
however, the coverage measurements were significantly lower than those
of limonene and ranged between (2 and 12) × 1013 molecules
cm–2. Flushing the surface with purified dry air
showed that VOC desorption is not a completely reversible process
at room temperature. The reversibly adsorbed fraction and the rate
coefficients of desorption, kdes, depended
inversely on the SiO2 relative abundance for both VOCs.
%I ACS Publications