Green rusts (GR, mixed FeII/FeIII layered double hydroxides) have been identified in FeIII/FeII transition zones in a variety of natural and engineered environments. Many of these environments are characterized by periodic or seasonal cycling of redox conditions that create the opportunity for cycling of Fe between oxidized and reduced forms. This study examined the effects of phosphate on dissimilatory iron reduction and the redox cycling of GR.  In our experiment, the oxidation of biogenic GR (produced during the bioreduction of lepidocrocite) by O2 to ferric GR occurred over a period of 24 h without the formation of other FeIII oxide phases. The biogenic GR was formed in the presence of phosphate and sorption of phosphate or silicate by GR has been shown to promote oxidation GR to ferric GR by suppressing GR dissolution. After re-inoculation, total FeII concentrations rebounded to pre-oxidation concentrations and ferri GR was reduced to GR.

Dissimilatory iron reduction and the redox cycling of green rust

244th National Meeting (2012)

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