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首页> 外文期刊>Environmental Science & Technology >Mechanisms Associated With The High Adsorption Of Dibenzo-p-dioxin From Water By Smectite Clays
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Mechanisms Associated With The High Adsorption Of Dibenzo-p-dioxin From Water By Smectite Clays

机译：蒙脱土对水中二苯并-对-二恶英的高吸附机理

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摘要

Clay minerals may be an important unrecognized sorptive phase for dioxins in soils and clay deposits. Smectites, especially Cs-saponite, effectively adsorbed dibenzo-p-dioxin (DD) from water, reaching 0.8% (wt/wt). Adsorption was promoted by exchangeable cations with low hydration energies, and negative charge in the smectite arising from the tetrahedral siloxane sheets. X-ray diffraction measurements revealed that as DD loading increased to ≥8000 mg/kg the clay basal spacing increased abruptly from 12.3 to 15.2 A demonstrating DD intercalation. The 12.3 A spacing provides an interlayer distance that closely matches the molecular thickness of DD. In this configuration DD is essentially dehydrated as it interacts with the opposing hydrophobic siloxane sheets and with coplanar Cs~+ via one of the dioxin ring oxygens. Ab initio calculations suggest that geometrical structures form at higher loadings in which intercalated DD molecules adopt a butterfly geometry sandwiched between dehydrated interlayer Cs~+ and the siloxane surface, consistent with the 15.2 A spacing, wherein Cs~+ interacts with dioxin ring oxygens and benzene ring π-electrons. Fourier transformation infrared measurements confirm that adsorbed DD is present in orientations that are not parallel with the interlayer planar siloxane surfaces of smectite.
机译：粘土矿物质可能是土壤和粘土沉积物中二恶英重要的重要未被认识的吸附相。绿土，特别是Cs-皂石有效地从水中吸附了二苯并-对-二恶英（DD），达到0.8％（wt / wt）。具有低水合能的可交换阳离子促进了吸附，而蒙脱石中的负电荷则由四面体硅氧烷片材引起。 X射线衍射测量表明，当DD负载增加到≥8000mg / kg时，粘土基础间距从12.3 A突然增加到15.2 A，这表明DD插入。 12.3间距提供的层间距离与DD的分子厚度紧密匹配。在该构型中，DD通过与二恶英环氧之一相互作用而与相对的疏水性硅氧烷片材和共面的Cs +相互作用时，基本上是脱水的。从头算计算表明，几何结构在较高的负载下形成，其中插入的DD分子采用夹在脱水夹层Cs〜+和硅氧烷表面之间的蝴蝶几何形状，与15.2 A间距一致，其中Cs〜+与二恶英环氧和苯相互作用环π电子。傅里叶变换红外测量结果证实了吸附的DD的存在方向与绿土的层间平面硅氧烷表面不平行。

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  • 来源
    《Environmental Science & Technology》 |2009年第8期|2777-2783|共7页
  • 作者

    CUN LIU; HUI LI; BRIAN J. TEPPEN; CLIFF T. JOHNSTON; STEPHEN A. BOYD;

  • 作者单位

    Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824;

    Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824;

    Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824;

    Crop, Soil and Environmental Sciences, Department of Agronomy, Purdue University, West Lafayette, Indiana 47907;

    Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824;

  • 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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