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首页> 外文期刊>Environmental Science & Technology >Impacts of Ionic Strength on Three-Dimensional Nanoparticle Aggregate Structure and Consequences for Environmental Transport and Deposition
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Impacts of Ionic Strength on Three-Dimensional Nanoparticle Aggregate Structure and Consequences for Environmental Transport and Deposition

机译：离子强度对三维纳米聚集体结构及其对环境运输和沉积的影响

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摘要

The transport of nanoparticles through aqueous systems is a complex process with important environmental policy ramifications. Ferrihydrite nanoparticles commonly form aggregates, with structures that depend upon solution chemistry. The impact of aggregation state on transport and deposition is not fully understood. In this study, small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were used to directly observe the aggregate structure of ferrihydrite nanoparticles and show how the aggregate structure responds to changing ionic strength. These results were correlated with complementary studies on ferrihydrite transport through saturated quartz sand columns. Within deionized water, nanoparticles form stable suspensions of low-density fractal aggregates that are resistant to collapse. The particles subsequently show limited deposition on sand grain surfaces. Within sodium nitrate solutions the aggregates collapse into denser dusters, and nanopartide deposition increases dramatically by forming thick, localized, and mechanically unstable deposits. Such deposits limit nanoparticle transport and make transport less predictable. The action of ionic strength is distinct from simpler models of colloidal stability and transport, in that salt not only drives aggregation or attachment but also alters the behavior of preexisting aggregates by triggering their collapse.
机译：纳米颗粒通过水系统的运输是一个复杂的过程，具有重要的环境政策影响。水铁矿纳米粒子通常形成聚集体，其结构取决于溶液化学性质。聚集状态对传输和沉积的影响尚不完全清楚。在这项研究中，小角度X射线散射（SAXS）和低温透射电子显微镜（cryo-TEM）用于直接观察水铁矿纳米颗粒的聚集结构，并显示聚集结构如何响应变化的离子强度。这些结果与关于水铁矿通过饱和石英砂柱输运的补充研究相关。在去离子水中，纳米颗粒形成稳定的低密度分形聚集体悬浮液，可防止崩解。颗粒随后在沙粒表面上显示出有限的沉积。在硝酸钠溶液中，聚集体塌陷成更密的喷粉器，并且通过形成厚的，局部的和机械不稳定的沉积物，纳米颗粒的沉积急剧增加。这样的沉积物限制了纳米颗粒的运输，并使运输更加难以预测。离子强度的作用不同于胶体稳定性和运输的简单模型，因为盐不仅驱动聚集或附着，而且还通过触发其崩溃来改变先前存在的聚集体的行为。

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  • 来源
    《Environmental Science & Technology》 |2014年第23期|13703-13710|共8页
  • 作者

    Benjamin A. Legg; Mengqiang Zhu; Luis R. Comolli; Benjamin Gilbert; Jillian F. Banfield;

  • 作者单位

    Department of Earth and Planetary Science, University of California, Berkeley, California 94720, United States,Pacific Northwest National Laboratory, Richland, WA 99352;

    Earth Science Division Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States,Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071;

    Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States;

    Earth Science Division Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States;

    Department of Earth and Planetary Science, University of California, Berkeley, California 94720, United States,Earth Science Division Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States;

  • 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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