Effects of redox cycling of Fe on the modification in nontronite structure induced by microbial Fe(III) reduction was investigated. Shewanella oneidensis MR-1 was incubated in M1 medium with Na-lactate as the electron donor and Fe in nontronite as the sole electron acceptor in anaerobic chamber for 21 days. O2 gas bubbling was then applied to the sample for 24 hours for re-oxidation. The extent of Fe(III) reduction reached up to 21.1% within 21 days. CEC measured in bioreduced sample showed a variation upon redox condition. XRD data indicated the formation of K-nontronite and mixed nontronite/illite layer whereas no discrete illite peak was observed. Vivianite was detected only in bio-reduced nontronite sample indicating the dissolution of nontronite. The direct observation by transmission electron microscopy verified the structural changes in nontonite corresponding to the various redox conditions. The long-term experiment for 6 months, is in progress, and results will be discussed.

Effects of various redox conditions on nontronite structure associated with microbial Fe(III) reduction

243rd National Meeting (2012)

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