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首页> 外文期刊>Environmental Science & Technology >Chemical Transformations during Aging of Zerovalent Iron Nanoparticles in the Presence of Common Groundwater Dissolved Constituents
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Chemical Transformations during Aging of Zerovalent Iron Nanoparticles in the Presence of Common Groundwater Dissolved Constituents

机译：普通地下水溶解成分存在下零价铁纳米粒子老化过程中的化学转化

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摘要

Nanoscale zerovalent iron (NZVI) that was aged in simulated groundwater was evaluated for alterations in composition and speciation over 6 months to understand the possible transformations NZVI could undergo in natural waters. NZVI was exposed to 10 mN of various common groundwater anions (Cl~-, NO_3~-, SO_4~(2-), HPO_4~(2-), and HCO_3~-) or to dissolved oxygen (saturated, ～9 mg/L). Fresh and exposed NZVI samples, along with Fe-oxide model compounds, were then analyzed using synchrotron radiation X-ray absorption spectroscopy (XAS) to yield both relative oxidation state, using the X-ray absorption near edge structure (XANES), and quantitative speciation information regarding the types and proportions of mineral species present, from analysis of the extended X-ray absorption fine structure (EXAFS). Over 1 month of aging the dissolved anions inhibited the oxidation of the NZVI to varying degrees. Aging for 6 months, however, resulted in average oxidation states that were similar to each other regardless of the anion used, exceptfor nitrate. Nitrate passivated the NZVI surface such that even after 6 months of aging the particles retained nearly the same mineral and Fe~0 content as fresh NZVI. Linear least-squares combination fitting (LCF) of the EXAFS spectra for 1 month-aged samples indicated that the oxidized particles remain predominantly a binary phase system containing Fe~0 and Fe_3O_4, while the 6 month aged samples contained additional mineral phases such as vivianite (Fe_3(PO_4)_2·8H_2U) and iron sulfate species, possibly schwertmannite (Fe~(3+) _(16)O_(16)(OH,SO_4)_(12-13)·10-12H_2O). The presence of these additional mineral species was confirmedrnusing synchrotron-based X-ray diffraction (XRD). NZVI exposed to water saturated with dissolved oxygen showed a rapid (<24 h) loss of Fe~0 and evolved both magnetite and maghemite (γ-Fe_2O_3) within the oxide layer. These findings have implications toward the eventual fate, transport, and toxicity of NZVI used for groundwater remediation.
机译：对在模拟地下水中老化的纳米级零价铁（NZVI）进行了6个月的成分和形态变化评估，以了解NZVI在天然水中可能发生的转化。 NZVI暴露于10 mN的各种常见地下水阴离子中（Cl〜-，NO_3〜-，SO_4〜（2-），HPO_4〜（2-）和HCO_3〜-）或溶解氧（饱和〜9 mg / L）。然后使用同步加速器辐射X射线吸收光谱（XAS）分析新鲜和暴露的NZVI样品以及铁氧化物模型化合物，以使用相对边缘结构（XANES）吸收X射线并同时定量分析相对氧化态通过扩展X射线吸收精细结构（EXAFS）的分析得出有关有关矿物种类和比例的物种信息。老化1个月以上，溶解的阴离子在不同程度上抑制NZVI的氧化。但是，老化6个月后，无论使用哪种阴离子，平均硝酸盐状态都彼此相似，但硝酸盐除外。硝酸盐钝化了NZVI表面，即使经过6个月的老化，颗粒仍保留了与新鲜NZVI几乎相同的矿物质和Fe〜0含量。 1月龄样品的EXAFS光谱的线性最小二乘组合拟合（LCF）表明，氧化颗粒主要保留了包含Fe〜0和Fe_3O_4的二元相体系，而6个月龄样品则包含了其他矿物相，例如云母石（Fe_3（PO_4）_2·8H_2U）和硫酸铁物种，可能是schwertmannite（Fe〜（3+）_（16）O_（16）（OH，SO_4）_（12-13）·10-12H_2O）。使用基于同步加速器的X射线衍射（XRD）确认了这些其他矿物质的存在。暴露在溶解氧饱和的水中的NZVI表现出Fe〜0的快速损失（<24小时），并且在氧化层内同时释放出磁铁矿和磁铁矿（γ-Fe_2O_3）。这些发现对用于地下水修复的NZVI的最终命运，运输和毒性具有影响。

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  • 来源
    《Environmental Science & Technology》 |2010年第9期|P.3455-3461|共7页
  • 作者

    BRIAN C. REINSCH; rnBRADY FORSBERG; rnR. LEE PENN; rnCHRISTOPHER S. KIM; rnGREGORY V. LOWRY;

  • 作者单位

    Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 152313 Center for the Environmental Implications of Nanotechnology (CEINT), Pittsburgh, Pennsylvania 15213;

    rnDepartment of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455;

    rnDepartment of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455;

    rnDepartment of Chemistry, Chapman University, Orange, California 92866;

    rnCarnegie Mellon University, Department of Civil and Environmental Engineering, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213-3890 Center for the Environmental Implications of Nanotechnology (CEINT), Pittsburgh, Pennsylvania 15213;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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