Optimizing Cr(VI) and Tc(VII) Remediation through Nanoscale Biomineral Engineering
Optimizing Cr(VI) and Tc(VII) Remediation through Nanoscale Biomineral Engineering
复制标题
DOI：
10.1021/es902119u
复制
发表时间：
2010-04-01
影响因子：
11.4
通讯作者：
Lloyd, Jonathan R.
中科院分区：
文献类型：
--
作者：
Cutting, Richard S.;Coker, Victoria S.;Lloyd, Jonathan R.
研究了铁（III）原料对硫还原地杆菌生产的磁性可回收生物源磁铁矿截留金属氧阴离子污染物能力的影响。通过还原/去除水中的Cr（VI）来探测生物磁石的反应性。细菌还原施氏锰矿粉末产生的纳米磁铁矿在还原Cr（VI）方面比水合铁“凝胶”衍生的生物磁铁矿或商业纳米级Fe(3)O(4)更有效。对暴露后磁铁矿表面的检查表明存在Cr（III）和Cr（VI）。在Fe L（2,3）边缘的x射线磁圆二色性（XMCD）研究表明，Cr（VI）还原“获得”的Fe（III）量不能完全由“损失”的Fe（II）来解释。Cr L（2,3）边缘XMCD谱发现，Cr（III）取代了两种生物成因磁铁矿中14% ~ 20%的八面体铁，形成了类似CrFe(2)O(4)的层。然而，schwertmanite衍生的生物磁铁矿与铁水合矿衍生的磁铁矿相关的Cr含量约为其两倍。柱状研究使用伽玛照相机成像（99）mTc（VII）放射性示踪剂，以可视化生物源磁铁矿在去除水中金属氧阴离子污染物方面的相对性能。再次，schwertmanite衍生的生物磁铁矿被证明能够比铁水合矿衍生的生物磁铁矿保留更多（约20%）（99m）Tc(VII)，这证实了生物磁铁矿的生产可以通过精心选择提供给Fe（III）还原细菌的Fe（III）矿物基质来进行有效的环境修复。
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 Fe(3)O(4). 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 similar to 14%-20% of octahedral Fe in both biogenic magnetites, producing a layer resembling CrFe(2)O(4). However, schwertmannite-derived biomagnetite was associated with approximately twice as much Cr as ferrihydrite-derived magnetite. Column studies using a gamma-camera to image a (99)mTc(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 (similar to 20%) (99m)Tc(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.