sp8b00178_si_001.pdf (13.74 MB)
Production of Atmospheric Organosulfates via Mineral-Mediated Photochemistry
journal contribution
posted on 2019-02-26, 19:14 authored by Mario Schmidt, Shawn M. Jansen van Beek, Maya Abou-Ghanem, Anton O. Oliynyk, Andrew J. Locock, Sarah A. StylerAlthough organosulfates
(ROSO3–) comprise
a significant component of secondary organic aerosol (SOA) mass, their
atmospheric formation mechanisms are not fully understood. Here, using
methacrolein as a model organosulfate precursor, we present a new,
mineral-mediated photochemical pathway for organosulfate formation.
First, we describe studies of TiO2-catalyzed formation
of the atmospherically important organosulfate hydroxyacetone sulfate
from methacrolein as a function of illumination time, catalyst loading,
sulfate concentration, counterion identity, and methacrolein concentration.
Then, we propose a sulfate radical-mediated mechanism for organosulfate
formation consistent with these observations. Finally, we show that
natural Ti-containing minerals and road dust not only catalyze the
formation of comparable amounts of hydroxyacetone sulfate to those
formed in the presence of commercial TiO2 but also facilitate
the production of additional organosulfate species. These results
highlight the complex nature of photochemistry at the surface of natural
mineral samples and underscore the need for further study of the role
of mineral–organic interactions in atmospheric organosulfate
formation.