Reactions of metal oxides with trace gases in the troposphere is an active research field since these species are the primary constituent of mineral dust. Other components, such as metal sulfides, are far less studied in terms of their atmospheric reactivity but could also impact the concentrations of trace gases in the troposphere. Pyrite (FeS2, iron(II) disulfide) is the most abundant of these. The role of pyrite in gas-surface reactions is essentially unknown. Of primary interest is the interaction of FeS2 with NOX species such as NO or NO2. NO and NO2 are considered two of the most important trace gases in the troposphere due to their high reactivity. To date, the only study that has been published on the interaction of a NOX species with FeS2 is a theoretical investigation of the adsorption of NO and NO2 on a FeS2 surface. Typical of theoretical studies, the FeS2 surface used in this investigation is pristine, i.e., there were no defects built into the surface. However, it is well known in surface science that defects are commonplace in "real" samples and are the sites of active chemistry. In this study, powdered FeS2 was reacted with NO and NO2 in separate experiments. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was utilized to identify any species formed on the surface of the FeS2 and to determine whether or not NO and NO2 dissociate upon adsorption. Mass spectrometry was used to detect gas-phase species produced. Product identity, possible reaction mechanisms and the kinetics of these reactions will be discussed.

Investigation of the reactions of NOx species with pyrite(FeS2)

255th National Meeting (2018)

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