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首页> 外文期刊>Environmental Science & Technology >Molecular Simulations Of Water And Ion Diffusion In Nanosized Mineral Fractures
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Molecular Simulations Of Water And Ion Diffusion In Nanosized Mineral Fractures

机译：水和离子在纳米矿物断裂中扩散的分子模拟

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摘要

Molecular dynamics simulations were carried out to investigate the effects of confinement and of the presence of the mineral surface on the diffusion of water and electrolyte ions in nanosized mineral fractures. Feldspar was used as a representative mineral because recent studies found that it is an important mineral that hosts contaminants within its intragrain fractures at the U.S. Department of Energy Hanford site. Several properties of the mineral-water interface were varied, such as the fracture width, the ionic strength of the contacting solution, andthe surface charge,to provide atomic-level insights into the diffusion of ions and contaminants within intragrain regions. In each case, the self-diffusion coefficient of water and that of the electrolyte ions were computed as a function of distance from the mineral surface. Our calculations reveal a 2.0-2.5 nm interracial region within which the self-diffusion coefficient of water and that of the electrolyte ions decrease as the diffusing species approach the surface. As a result of the extent of the interfacial region, water and electrolyte ions are predicted to never reach bulk-like diffusion in fractures narrower than approximately 5 nm. The average diffusion coefficient along the mineral fracture was computed as a function of fracture width and indicated that the surface effects only become negligible for fractures several tens of nanometers wide. The molecular dynamics results improve our conceptual models of ion transport in nanoscale pore regions surrounded by mineral surfaces in porous media.
机译：进行了分子动力学模拟以研究限制作用和矿物表面的存在对纳米级矿物裂缝中水和电解质离子扩散的影响。长石被用作代表性矿物，因为最近的研究发现，它是一种重要的矿物，在美国能源部汉福德矿区的晶粒内裂缝中蕴藏着污染物。改变矿泉水界面的几个特性，例如断裂宽度，接触溶液的离子强度和表面电荷，以提供原子级的洞察力，了解离子和污染物在颗粒区域内的扩散。在每种情况下，水和电解质离子的自扩散系数都是根据距矿物表面距离的函数来计算的。我们的计算揭示了一个2.0-2.5 nm的异族区域，在该区域内，水和电解质离子的自扩散系数随着扩散物质接近表面而减小。由于界面区域的大小，预计水和电解质离子将不会在小于约5 nm的裂缝中达到块状扩散。计算出沿着矿物裂缝的平均扩散系数是裂缝宽度的函数，并且表明表面效应仅对于几十纳米宽的裂缝可忽略不计。分子动力学结果改善了我们在多孔介质中被矿物表面围绕的纳米级孔区域中离子迁移的概念模型。

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  • 来源
    《Environmental Science & Technology》 |2009年第3期|777-782|共6页
  • 作者

    SEBASTIEN KERISIT; CHONGXUAN LIU;

  • 作者单位

    Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352;

  • 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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  • 正文语种 eng
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