【作者】 廖华丰；

【导师】 陶涛；

【作者基本信息】 华中科技大学 ， 市政工程， 2009， 硕士

【摘要】 本文综述和分析了重金属污染土壤的来源及危害,简要介绍了重金属污染土壤修复的国内外研究现状以及淋洗剂提取重金属的反应机理。在对重金属污染土壤修复技术进行了比较深入分析的基础上,通过模拟土壤重金属污染,探究了重金属污染土壤中重金属形态分布;通过淋洗剂浸提实验,分析了壳聚糖、柠檬酸三钠、EDTA(乙二胺四乙酸)三种淋洗剂,对铜、镍、铬三种重金属污染土壤提取效果并遴选出了适合的淋洗剂;同时应用一级动力学方程、二级动力方程、双常数模型、Elovich模型四种常用动力学模型对淋洗剂提取重金属的反应过程进行了动力学特性研究。通过研究得出以下主要结论:(1)配制的铜、镍重金属污染土样中,其可交换态、碳酸盐结合态、铁锰氧化物结合态、硫化物及有机结合态、残渣态所占重金属总含量的比重,铜分别为31.95%、7.29%、23.51%、7.05%、30.20%,镍分别为29.53%、3.46%、8.29%、1.23%、57.49%;采用重铬酸钾配制的铬污染土壤,铬主要以六价铬的形式存在,仅有微量三价铬。(2)对于铜污染土壤,三种淋洗剂提取效果排序为:壳聚糖>EDTA>柠檬酸三钠;反应时间对三种淋洗剂的提取率的影响均较小;随着pH值的增大,三种淋洗剂的提取率均下降,趋势很明显。(3)对于镍污染土壤,三种淋洗剂提取效果排序为:壳聚糖>EDTA>柠檬酸三钠;三种淋洗剂提取率均随反应时间的延长而有所提高;随着pH值的增大,壳聚糖、柠檬酸三钠的提取率均有明显下降,而pH对EDTA的提取率影响不明显,提取率稳定在31%附近。(4)对于铬污染土壤,三种淋洗剂提取效果排序为:柠檬酸三钠>EDTA>壳聚糖;反应时间对三种淋洗剂提取率的影响均不是很明显,提取率浮动在3%以内;pH值对EDTA、壳聚糖的提取率均无明显影响,提取率比较稳定,随着pH的升高,柠檬酸三钠对铬的提取率有小幅增长。(5)不同的重金属与不同的淋洗剂之间的反应适用的动力学模型并不一致,总体上四种模型的拟合度排序为:Elovich模型>双常数模型>二级动力方程>一级动力方程。但四种模型的拟合结果并不显著,这是由于淋洗剂提取污染土壤中重金属的反应是一个及其复杂的反应动力学过程,很难用现有的某一种具体动力学模型来描述。更多还原

【Abstract】 This paper summarized and analyzed the source & harm of the heavy metal contaminated soil, briefly introduced the research situation of the remediation of heavy metal contaminated soil at home and abroad and the reaction mechanism of extracting heavy metal with eluents .Base on the deeply analysis of the technology of remediating heavy metal contaminated soil, this paper investigated the speciation distribution of heavy metal in the heavy metal contaminated soil through simulating the polluting of heavy metal on the soil.In the extraction test of eluents, with the chitosan,sodium citrate ,EDTA as eluents, the different eluents were screened from the analysis of screening effect in the soil polluted by heavy metal: cuprum ,nickel ,chrome. Then kinetic attributes of the reaction process of extracting heavy metal with eluents was investigated ,applying the 4 common kinetic models : the first-order kinetics equation ,the second-order kinetics equation,the double constant model,the kinetics model.The main conclusions produced through the research:(1) The proportion of exchangeable speciation , copperbonded to carbonates,Fe-mn oxide form ,sulfide & bound organic , residual state of cuprum and nickel in the confected heavy metal contaminated soil were 31.95%,7.29%,23.51%,7.05%,30.20% and 29.53%, 3.46%, 8.29%,1.23%,57.49%; the chromium in the potassium dichromate contaminated soil was almost hexad.(2) In the cuprum contaminated soil , the sequence of extraction effect was : chitosan > EDTA> sodium citrate ; the reaction time had a small effect on the extraction proportion of the 3 kinds of eluents; the trend was obvious that the extraction proportion of the 3 kinds of eluents all dropped as the value of pH increased.(3) In the nickel contaminated soil , the sequence of extraction effect was : chitosan > EDTA> sodium citrate ; the extraction proportion of the 3 kinds of eluents increased as the reaction time prolonged;the extraction proportion of chitosan ,sodium citrate dropped obviously as the value of pH increased, but the extraction proportion of EDTA on which the value of pH did not have a significant effect, maintained at about 31%. (4) In the chrome contaminated soil ,the sequence of extraction effect was : sodium citrate > EDTA>chitosan ; the reaction time did not have a significant effect on the extraction proportion of 3 kinds of eluents , the extraction proportion waved in range of 3 percentage points; the extraction proportion of EDTA on which the value of pH did not have a significant effect , kept stable.(5) The kinetic models applied in the reaction between different heavy metals and different eluents were different. The sequence of fitting degree of the four models general was: the Elovich model > the double constant model >the second-order kinetics equation > the first-order kinetics equation.But the fitting results of the four models were not significant. Because the reaction of extracting heavy metal in the polluted soil with eluents was a very complex reaction kinetic process, which was difficult to describe through a simple model.更多还原