THE CHARACTERIZATION OF ADSORBED FE(II) AND ITS REACTIVITY WITH NITRITE
EMSL Project ID
25595
Abstract
Nitrate-dependent, iron(II) oxidation is an important process in the inhibition of soil iron(III) reduction. One important reaction that contributes to this process is chemical reoxidation of solution Fe(II) by nitrite, yet the role of adsorbed Fe(II) in nitrite reduction is poorly understood. This process is relevant to soil/sediment systems under the influence of microbial iron(III) reduction in environments with elevated nitrate levels, such as those at Department of Energy sites. Accordingly, the overall goal of this proposed project is to investigate the reactivity of adsorbed Fe(II) with nitrite. This goal will be achieved through two specific objectives: 1) Investigate adsorbed Fe(II) surface complexes on reference minerals (gibbsite, kaolinite, and Fe(III) oxides) and natural materials (clay fractions from the Sadler silt loam and McCracken county soils) using cutting-edge spectroscopic techniques (57Fe-Mössbauer spectroscopy, optical spectroscopy, x-ray absorption spectroscopy, and electron paramagnetic resonance spectroscopy) and 2) Assess the reactivity of well-characterized Fe(II) surface complexes with nitrite. We propose to collaborate with Dr. Ravi Kukkadapu as a standard access user at EMSL to perform 57Fe-Mössbauer spectroscopy. The proposal is non-proprietary in nature and is in response to the geochemistry/biogeochemistry science theme. This proposed work is both creative and original because it combines spectroscopic tools with wet chemical experiments to unravel the complexities of adsorbed Fe(II) surface complexes and their reactivity with nitrite. An expected outcome is a molecular-level understanding of surface Fe(II) complexes and fundamental rate data of adsorbed Fe(II)-nitrite interactions. These data can be incorporated in reactive transport models. This proposed research fits in well with EMSL's science theme of geochemistry/biogeochemistry because we intend to elucidate fundamental electron transfer processes between adsorbed Fe(II) forms and NO2-. This research is a timely pursuit given the abundance of iron minerals and nitrate in Department of Energy subsurface environments and the desire to implement bioreduction methods to minimize contaminant mobility.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-07-01
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members