Enhancement of Biological Reduction of Hematite by Electron Shuttling and Fe(II) Complexation
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- 作者：Richard A. Royer ; William D.Burgos ; Angela S. Fisher ; RichardF. Unz ; and Brian A. Dempsey
- 刊名：Environmental Science & Technology
- 出版年：2002
- 出版时间：May 1, 2002
- 年：2002
- 卷：36
- 期：9
- 页码：1939 - 1946
- 全文大小：116K
- 年卷期：v.36,no.9(May 1, 2002)
- ISSN：1520-5851
文摘
Natural organic matter (NOM) enhancement of thebiological reduction of hematite (
-Fe2O3) by the dissimilatoryiron-reducing bacterium Shewanella putrefaciens strainCN32 was investigated under nongrowth conditions designedto minimize precipitation of biogenic Fe(II). Hydrogenserved as the electron donor. Anthraquinone-2,6-disulfonate(AQDS), methyl viologen, and methylene blue [quinoneswith an Ew0 (pH 7) of 0.011 V or less], ferrozine [a strongFe(II) complexing agent], and characterized aquatic NOM(Georgetown NOM or Suwannee River fulvic acid)enhanced bioreduction in 5-day experiments whereas 1,4-benzoquinone (Ew0 value = 0.280 V) did not. A linearrelationship existed between total Fe(II) produced andconcentrations of ferrozine or NOM but not quinones, exceptin the case of methylene blue. Such a linear relationshipbetween Fe(II) and methylene blue concentrations could bedue to the systems being far undersaturated with respectto methylene blue or the loss of the thermodynamicdriving force. A constant concentration of AQDS and variableconcentrations of ferrozine produced a linear relationshipbetween total Fe(II) produced and the concentration offerrozine. Enhancement effects of both AQDS and ferrozinewere additive. NOM may serve as both an electronshuttle and an Fe(II) complexant; however, the concentrationdependence of hematite reduction with NOM was moresimilar to ferrozine than quinones. NOM likely enhanceshematite reduction initially by electron shuttling and thenfurther by Fe(II) complexation, which prevents Fe(II) sorptionto hematite and cell surfaces.
-Fe2O3) by the dissimilatoryiron-reducing bacterium Shewanella putrefaciens strainCN32 was investigated under nongrowth conditions designedto minimize precipitation of biogenic Fe(II). Hydrogenserved as the electron donor. Anthraquinone-2,6-disulfonate(AQDS), methyl viologen, and methylene blue [quinoneswith an Ew0 (pH 7) of 0.011 V or less], ferrozine [a strongFe(II) complexing agent], and characterized aquatic NOM(Georgetown NOM or Suwannee River fulvic acid)enhanced bioreduction in 5-day experiments whereas 1,4-benzoquinone (Ew0 value = 0.280 V) did not. A linearrelationship existed between total Fe(II) produced andconcentrations of ferrozine or NOM but not quinones, exceptin the case of methylene blue. Such a linear relationshipbetween Fe(II) and methylene blue concentrations could bedue to the systems being far undersaturated with respectto methylene blue or the loss of the thermodynamicdriving force. A constant concentration of AQDS and variableconcentrations of ferrozine produced a linear relationshipbetween total Fe(II) produced and the concentration offerrozine. Enhancement effects of both AQDS and ferrozinewere additive. NOM may serve as both an electronshuttle and an Fe(II) complexant; however, the concentrationdependence of hematite reduction with NOM was moresimilar to ferrozine than quinones. NOM likely enhanceshematite reduction initially by electron shuttling and thenfurther by Fe(II) complexation, which prevents Fe(II) sorptionto hematite and cell surfaces.