Linking Thermodynamics to Pollutant Reduction Kinetics by Fe Bound to Iron Oxides.

Numerous studies have reported that pollutant reduction rates by ferrous iron (Fe) are substantially enhanced in the presence of an iron (oxyhydr)oxide mineral. Developing a thermodynamic framework to explain this phenomenon has been historically difficult due to challenges in quantifying reduction potential ( E) values for oxide-bound Fe species. Recently, our group demonstrated that E values for hematite- and goethite-bound Fe can be accurately calculated using Gibbs free energy of formation values.

Thermodynamic Characterization of Iron Oxide-Aqueous Fe(2+) Redox Couples.

Iron is present in virtually all terrestrial and aquatic environments, where it participates in redox reactions with surrounding metals, organic compounds, contaminants, and microorganisms. The rates and extent of these redox reactions strongly depend on the speciation of the Fe2+ and Fe3+ phases, although the underlying reasons remain unclear. In particular, numerous studies have observed that Fe2+ associated with iron oxide surfaces (i.