Iron(II) sulfides (FeS) are a likely endpoint for engineered iron-based nanomaterials when released into natural environments, as well as a ubiquitous component of anaerobic sediments and of importance to the biogeochemical cycles of both iron and sulfur. Although relatively stable when conditions remain reducing, when exposed to oxygen during a disturbance such as excavation or natural tidal flushing, both the Fe(II) and S(−II) are readily oxidized, forming a range of transient minerals and dissolved species on the eventual pathway to thermodynamically stable Fe(III) and sulfate. Throughout this process, hydrogen peroxide is formed resulting in a system containing both Fe(II) and H<sub>2</sub>O<sub>2</sub> and therefore conducive to the Fenton reaction. These reaction pathways have been examined in suspensions of synthetic FeS buffered at pH 8 with particular emphasis on the ability of the system to oxidize formate as a simple example of an organic compound. The solid phase transformation of the Fe-mineral has also been probed using Fe K-edge X-ray absorption spectroscopy in order to understand the nature of the intermediate and final-state mineralogy as well as to deduce the potential role of the mineral phases in driving the observed oxidation capacity of the system.

Oxidation of synthetic iron(II) monosulfide at circumneutral pH when exposed to aerobic conditions: Fe-mineral transformations and oxidizing capacity of the system

253rd National Meeting (2017)

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