Optimizing Cr(VI) and Tc(VII) Remediation through Nanoscale Biomineral Engineering

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• 作者：Richard S. Cutting ; Victoria S. Coker ; Neil D. Telling ; Richard L. Kimber ; Carolyn I. Pearce ; Beverly L. Ellis ; Richard S. Lawson ; Gerrit van der Laan ; Richard A. D. Pattrick ; David J. Vaughan ; Elke A
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：April 1, 2010
• 年：2010
• 卷：44
• 期：7
• 页码：2577-2584
• 全文大小：232K
• 年卷期：v.44,no.7(April 1, 2010)
• ISSN：1520-5851

文摘

The influence of Fe(III) starting material on the ability of magnetically recoverable biogenic magnetites produced by Geobacter sulfurreducens to retain metal oxyanion contaminants has been investigated. The reduction/removal of aqueous Cr(VI) was used to probe the reactivity of the biomagnetites. Nanomagnetites produced by the bacterial reduction of schwertmannite powder were more efficient at reducing Cr(VI) than either ferrihydrite “gel”-derived biomagnetite or commercial nanoscale Fe₃O₄. Examination of post-exposure magnetite surfaces indicated both Cr(III) and Cr(VI) were present. X-ray magnetic circular dichroism (XMCD) studies at the Fe L_2,3-edge showed that the amount of Fe(III) “gained” by Cr(VI) reduction could not be entirely accounted for by “lost” Fe(II). Cr L_2,3-edge XMCD spectra found Cr(III) replaced 14%−20% of octahedral Fe in both biogenic magnetites, producing a layer resembling CrFe₂O₄. However, schwertmannite-derived biomagnetite was associated with approximately twice as much Cr as ferrihydrite-derived magnetite. Column studies using a γ-camera to image a ⁹⁹mTc(VII) radiotracer were performed to visualize the relative performances of biogenic magnetites at removing aqueous metal oxyanion contaminants. Again, schwertmannite-derived biomagnetite proved capable of retaining more (20%) ⁹⁹mTc(VII) than ferrihydrite-derived biomagnetite, confirming that the production of biomagnetite can be fine-tuned for efficient environmental remediation through careful selection of the Fe(III) mineral substrate supplied to Fe(III)-reducing bacteria.