Back to overview

Linking Thermodynamics to Pollutant Reduction Kinetics by Fe 2+ Bound to Iron Oxides

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Stewart Sydney M., Hofstetter Thomas B., Joshi Prachi, Gorski Christopher A.,
Project Characterization of the redox properties of iron minerals by combined electrochemical and spectroscopic analyses
Show all

Original article (peer-reviewed)

Journal Environmental Science & Technology
Volume (Issue) 52(10)
Page(s) 5600 - 5609
Title of proceedings Environmental Science & Technology
DOI 10.1021/acs.est.8b00481

Open Access

Type of Open Access Publisher (Gold Open Access)


Numerous studies have reported that pollutant reduction rates by ferrous iron (Fe2+) 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 (EH) values for oxide-bound Fe2+ species. Recently, our group demonstrated that EH values for hematite- and goethite-bound Fe2+ can be accurately calculated using Gibbs free energy of formation values. Here, we tested if calculated EH values for oxide-bound Fe2+ could be used to develop a free energy relationship capable of describing variations in reduction rate constants of substituted nitrobenzenes, a class of model pollutants that contain reducible aromatic nitro groups, using data collected here and compiled from the literature. All the data could be described by a single linear relationship between the logarithms of the surface-area-normalized rate constant (kSA) values and EH and pH values [log(kSA) = −EH/0.059 V − pH + 3.42]. This framework provides mechanistic insights into how the thermodynamic favorability of electron transfer from oxide-bound Fe2+ relates to redox reaction kinetics.