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首页> 外文学位 >Nonequilibrium transport of heavy metals in soils and its influence on soil remediation.
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Nonequilibrium transport of heavy metals in soils and its influence on soil remediation.

机译：土壤中重金属的非平衡迁移及其对土壤修复的影响。

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摘要

With increasing concern about soil and groundwater contamination, research on contaminant transport modeling and remediation technology has grown rapidly. Nonequilibrium transport of heavy metals resulting from rate-limited reactions in soils under natural and remediation conditions was investigated with batch, column, and sequential extraction experiments together with transport modeling in this study.; Higher pore-water velocity that allowed shorter residence time and lower temperature that reduced the sorption rate resulted in nonequilibrium transport, whereas the reverse promotes equilibrium transport. Diffusion process was probably the rate-limiting step. The disparity of transport behavior was related to both residence time and reaction time.; Competition among heavy metals for sorption not only suppressed the sorption equilibrium but changed the corresponding transport behavior. The specific sorption of Cd, which was found rate-limited, was nearly eliminated by the presence of Cu, leading to shorter apparent equilibrium time and thereby equilibrium transport of Cd. In addition, the concentration-dependent relative contribution of nonlinear and rate-limited sorption to nonideal transport was assessed, in which rate-limited sorption was important only at sufficiently low metal loading. It has demonstrated that the multiple approaches using batch, sequential extraction and column experiments can provide a better analysis of the transport behavior.; Nonequilibrium transport of metal complexes was also demonstrated to be important during EDTA-flushing. While Cu extraction by EDTA was efficient, soil mineral and organic matter dissolution that would significantly alter the soil properties should not be neglected. The EDTA-promoted extraction and dissolution, which are rate-limited, could be described by the respective second-order kinetics. The proposed transport model successfully simultaneously simulated the nonequilibnum transport of all extracted and dissolved metals, taking into account the factors of metal competition for EDTA, concentration of EDTA and extractable amount of metals.
机译：随着对土壤和地下水污染的日益关注，对污染物迁移模型和修复技术的研究迅速发展。在自然和修复条件下，土壤中限速反应引起的重金属非平衡迁移通过分批，柱和顺序提取实验以及迁移模型进行了研究。较高的孔隙水速度可以缩短停留时间，而较低的温度则会降低吸附速率，从而导致非平衡迁移，反之则促进了平衡迁移。扩散过程可能是限速步骤。运输行为的差异与停留时间和反应时间有关。重金属之间的吸附竞争不仅抑制了吸附平衡，而且改变了相应的传输行为。铜的存在几乎消除了速率受限的镉的特定吸附，从而缩短了表观平衡时间，从而平衡了镉的迁移。另外，评估了非线性和速率受限吸附对非理想迁移的浓度依赖性相对贡献，其中速率受限吸附仅在足够低的金属负载下才重要。已经证明，使用批处理，顺序提取和柱实验的多种方法可以更好地分析运输行为。在EDTA冲洗过程中，金属配合物的非平衡转运也很重要。尽管通过EDTA萃取铜是有效的，但不应忽略会显着改变土壤性质的土壤矿物质和有机物溶解。 EDTA促进的萃取和溶解受到速率的限制，可以通过各自的二级动力学来描述。考虑到金属对EDTA的竞争，EDTA的浓度和金属的可提取量等因素，所提出的传输模型成功地同时模拟了所有提取和溶解的金属的非平衡迁移。

著录项

  • 作者

    Tsang, Chiu Wa.;

  • 作者单位

    Hong Kong University of Science and Technology (People's Republic of China).;

  • 授予单位 Hong Kong University of Science and Technology (People's Republic of China).;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 229 p.
  • 总页数 229
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

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