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首页> 外文学位 >Phenanthrene sorption/desorption mechanisms and rapid prediction of long-term desorption rates using superheated water.
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Phenanthrene sorption/desorption mechanisms and rapid prediction of long-term desorption rates using superheated water.

机译：菲吸附/解吸机理以及使用过热水的长期解吸速率的快速预测。

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摘要

Hydrophobic organic contaminants (HOCs) in subsurface systems pose carcinogenic threats to drinking water supplies, but remediation is limited by sorption to and slow desorption from soils and sediments. Thus, in order to predict associated risk and plan effective remediation strategies, HOC sorption and desorption processes must be understood in a predictable manner.;Soil and sediment organic matter (SOM) is typically the dominant sorption domain of HOCs. It has been hypothesized that sorption capacity and isotherm nonlinearity are a function of the degree of condensation and aromatization of SOM resulting from natural diagenetic processes, but this has not been directly tested because natural diagenesis occurs over extremely long time scales. To overcome the barrier of geologic time, a method for artificially inducing SOM diagenesis through superheated water extraction and reaction was developed. Subsequent phenanthrene sorption equilibria for artificially aged samples provide direct evidence that sorption capacity and isotherm nonlinearity both increase with increasing degree of SOM condensation and aromatization.;Desorption of HOCs from soils and sediments into interstitial water can take months or years to reach an endpoint. This study improved current experimental techniques and characterized long-term phenanthrene desorption as a function of soil and sediment organic matter type, loading level, and aging time.;Rate limiting mechanisms responsible for slow HOC desorption from soils and sediments are poorly understood and actively debated in the scientific literature. Through determining apparent activation energies of phenanthrene desorption from soils and sediments and identification of an isokinetic temperature, this study supports the theory that intraorganic matter diffusion is a dominant rate limiting mechanism for slow desorption.;A laboratory technique for rapidly predicting the long-term HOC desorption behavior in a contaminated soil or sediment would be invaluable for engineers and scientists planning remediation. Schemes and/or grappling with difficult alternative remediation endpoint decisions. Therefore, this study also developed a superheated water extraction technique for rapid prediction of long-term phenanthrene desorption. Proposed methodologies have great practical significance because desorption at ambient temperatures requires months or years, while high temperature experiments are accomplished in hours or days.
机译：地下系统中的疏水性有机污染物（HOCs）对饮用水的供应构成了致癌威胁，但是由于土壤和沉积物的吸附和从土壤和沉积物中的缓慢解吸，其修复受到了限制。因此，为了预测相关风险并计划有效的补救策略，必须以可预测的方式理解HOC的吸附和解吸过程。土壤和沉积物有机物（SOM）通常是HOC的主要吸附域。据推测，吸附能力和等温线非线性是自然成岩过程引起的SOM缩合和芳构化程度的函数，但是由于自然成岩作用发生的时间非常长，因此尚未进行直接测试。为了克服地质时间的障碍，开发了一种通过过热水萃取和反应人工诱导SOM成岩的方法。随后人工老化样品的菲吸附平衡提供了直接的证据，表明吸附能力和等温线非线性都随着SOM缩合和芳构化程度的增加而增加。; HOC从土壤和沉积物中解吸到间隙水中可能要花费数月或数年才能达到终点。这项研究改进了当前的实验技术，并表征了长期菲解吸作用与土壤和沉积物有机物类型，负荷水平和老化时间的关系。对导致土壤和沉积物中HOC缓慢解吸的速率限制机制知之甚少，并进行了积极的辩论在科学文献中。通过确定从土壤和沉积物中菲解吸的表观活化能并确定等速温度，本研究支持以下理论：有机物扩散是缓慢解吸的主要速率限制机制。一种快速预测长期HOC的实验室技术对于计划进行修复的工程师和科学家而言，在受污染的土壤或沉积物中的解吸行为将是无价的。计划和/或难以解决的补救终结点决策。因此，本研究还开发了一种过热水提取技术，用于快速预测长期菲的脱附。所提出的方法学具有很大的实际意义，因为在环境温度下的解吸需要数月或数年，而高温实验则需要数小时或数天。

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  • 作者

    Johnson, Martin David.;

  • 作者单位

    University of Michigan.;

  • 授予单位 University of Michigan.;
  • 学科 Engineering Chemical.;Engineering Civil.;Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 198 p.
  • 总页数 198
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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