【作者】 刘霞；

【导师】 杨亚提；

【作者基本信息】 西北农林科技大学 ， 环境工程， 2012， 硕士

【摘要】 近年来重金属污染事件频发，环保部日前审议通过《“十二五”危险废物污染防治规划》中表示，2012年的环保专项行动要加强重金属污染防治，坚决遏制重金属污染事件的发生。随着我国工业的加速发展，特别是重金属排放企业的增多，导致环境压力越来越大。目前修复重金属污染土壤的方法有物理、化学和生物方法，由于物理修复费用较高，化学修复易对环境产生二次污染，生物修复所需时间较长，所以采用物理修复和化学修复相结合的土壤淋洗技术便应运而生。土壤淋洗修复技术的关键在于淋洗剂的选择，螯合剂和表面活性剂由于具有较强的螯合、络合、增溶等特征而被广泛使用。本文以Cu、Pb为重金属代表，采用批试验和柱淋洗方法，选用螯合剂EDTA和柠檬酸（CIT）以及阴离子表面活性剂十二烷基硫酸钠（SDS）和生物表面活性剂鼠李糖脂（RL2）作为淋洗剂，研究了4种淋洗剂对塿土中Cu和Pb的淋洗效果及淋洗动力学特征，以及最佳的淋洗条件，比较了淋洗前后重金属的形态变化特征，为石灰性土壤重金属污染的治理提供了科学依据。所得结论如下：（1）螯合剂、表面活性剂对Cu、Pb的淋洗动力学研究表明，2种螯合剂对Cu、Pb的淋洗是一个相对慢速的过程，240min左右时淋洗基本达到平衡；而2种表面活性剂对Cu、Pb的淋洗的是一个相对快速的过程，在60min左右达到平衡。4种淋洗剂对Cu的淋洗量依次表现为EDTA>CIT>RL2>SDS；对Pb的淋洗量依次表现为EDTA>CIT>SDS>RL2。4种淋洗剂中，EDTA对污染塿土中Cu、Pb的淋洗效果最好；双常数方程和准二级方程能较好地描述4种淋洗剂淋洗污染塿土中Cu、Pb的动力学特征，双常数方程中的参数b可描述不同有机配位体对污染土壤中Cu和Pb淋洗快慢的特征。（2）不同淋洗剂在不同条件下对污染塿土中Cu、Pb的淋洗修复平衡研究表明，EDTA和CIT溶液淋洗塿土中Cu、Pb的最适条件为：水土比20:1、浓度0.01mol·L-1、pH7、溶液自身离子强度；RL2溶液在水土比20:1、浓度为0.02mol·L-1、pH8、溶液自身离子强度条件下淋洗污染塿土中铜、铅效果最佳；SDS易与塿土中的Ca2+发生沉淀，不宜采用其作为石灰性土壤的淋洗剂。多次累积淋洗结果表明，EDTA、CIT和RL2可以有效地去除污染塿土中的Cu，EDTA可作为石灰性污染塿土中Pb的最佳淋洗剂。（3）RL2与螯合剂复合对污染塿土中Cu、Pb的淋洗效果表明，当RL2浓度在100CMC时，对两种螯合剂淋洗Cu具有促进作用，对EDTA淋洗Pb具有促进作用；而当RL2浓度在200CMC时，对两种螯合剂淋洗Cu则表现为抑制作用，对CIT淋洗Pb的影响不大。（4）选用土柱淋洗法修复Cu、Pb污染塿土的效果表明，EDTA、CIT与RL2在1mL·min^-1流速下，土柱淋滤污染塿土中Cu、Pb的效果较好。三种淋洗剂淋洗出Cu和Pb的量随着累积体积数目的增大而逐渐增加，对Cu和Pb累积淋洗量表现为EDTA>CIT>RL2。在淋洗的初期，EDTA和CIT对重金属的去除效果最明显，其中EDTA淋洗出Cu和Pb的量在初始阶段达到峰值点，分别为15.00mg·kg^-1和71.36mg·kg^-1，CIT淋洗出Cu的量的最高值为15.27mg·kg^-1。形态分级结果表明，用EDTA和EDTA-RL2复合溶液淋洗后，对各种形态Cu和Pb的去除率都较大；CIT、RL2和CIT-RL2复合溶液能有效去除交换态、吸附态和有机结合态重金属，大大降低了重金属的环境风险性，也说明用CIT与RL2作淋洗剂对重金属污染塿土具有较大的潜力。更多还原

【Abstract】 In recent years, the contamination ancident of heavy metals in the environment happenedfrequently. Ministry of Environmental Protection has reviewed and approved the "12thFive-hazardous waste pollution prevention planning", which said that the environmentalprotection special action in2012is to strengthen the heavy metal pollution prevention, andcurb resolutely the occurrence of heavy metal contamination. With the development ofChina’s industry, especially the emission of heavy metals enterprise was increasing, resultedin increasing pressure on the environment. There are physical, chemical and biologicalmethods to remediate the heavy metal contaminated soil, physical method costs higher,chemical remediation is easy to produce secondary pollution to the environment,bioremediation required longer time, so the combination of physical repair and chemicalrepair,that is soil washing technologies have come into being. The soil washing remediationtechniques was critical to the choice of the eluent, chelating agents and surfactant are widelyused with a strong chelating complexation, solubilization characteristics. It was found that theeffects of surfactant treatment in heavy metal contaminated soil is good, especially after theaddition of EDTA is even more significant. In this paper, Cu and Pb was choose torepresentative, using batch tests and column leaching methods, choosing the chelating agentEDTA and citric acid （CIT） and the anionic surfactant sodium dodecyl sulfate （SDS） and thebiosurfactant rhamnolipid （RL2）, to research the desorption effect and desorption kineticcharacteristics of Cu and Pb in lou soil, as well as the best leaching conditions, to select theoptimal chelating agent/surfactant concentration ratio, and compared the leaching of heavymetals before and after morphological variation, and provide a scientific basis for heavy metalpollution of the calcareous soil.（1）The kinetics of leaching Cu and Pb in contaminated Lou soil using different eluensshowed that the Cu and Pb leaching were slow process with the two kinds of chelating agentstreatment, it was about240minutes to reach leaching equilibrium. while the Cu and Pbleaching was rapid process with two surfactants treatment, and it was about60minutes toreach leaching equilibrium. The leaching amount of Cu followed the trend of EDTA> CIT>RL2> SDS, the leaching amount of Pb followed the trend of EDTA> CIT> SDS> RL2.The EDTA leaching of Cu and Pb in the contaminated Lou soil was the best among the four kindsof leaching agents; The two constant rate and pseudo-second-order equations were well fit theexperimental data. The parameters b of the two-constant equation model could be used todescribe the leaching rate.（2）The equilibrium research of leaching Cu and Pb in contaminated Lou soil usingdifferent eluents showed that the optimal conditions of EDTA and CIT solutions are the ratioof water to soil20:1, solution concentration0.01mol·L^-1, pH7and the solution ionic strength;RL2solution is concentration0.02mol·L^-1, pH8, the solution ionic strength;SDS should notbe used as leaching agent, because it’s easy to precipitate with Ca²+in the Lou soil. Theresults of the cumulative leaching indicated that EDTA、CIT and RL2can effective removedCu in contaminated Lou soil as well as EDTA was effective to the removal of Pb fromcontaminated soil.（3）The results of leaching Cu and Pb in contaminated Lou soil by chelating agent andRL2complexed showed that the concentration of RL2was100CMC,it has stimulative effectfor two kinds of chelating agent leaching Cu, and the concentration of RL2was200CMC, theleaching of Cu was inhibited. When the concentration of RL2was100CMC, it hasstimulative effect for the leaching of Pb with EDTA, and when the concentration of RL2in200CMC, the leaching of Pb with EDTA were inhibited; the mixde RL2and CIT leaching Pbhad little effect on leaching.（4）The results of column leaching Cu and Pb in contaminated Lou soil showed the effectof column leaching Cu and Pb was much better in1mL min^-1flow rate,.With the cumulativevolume increased, the cumulative leaching amount of Cu and Pb was increased gradually, thecumulative leaching amount of Cu and Pb followed the trend of EDTA> CIT> RL2.Theremoval of Cu and Pb by EDTA and CIT was most obviously in the early stages ofleaching,and the cumulative leaching amount of Cu and Pb by EDTA reach the peakpoints,which is15.00mg·kg^-1and71.36mg·kg-1respectively, the cumulative leaching amountof Cu by CIT is15.27mg kg^-1. The fractionation results showed that after EDTA andEDTA-RL2leaching, every fraction of Cu and Pb were reduced obviously; CIT, RL2, and themixed of CIT and RL2solution leaching can effectively remove the exchangeable fraction,adsorption states and organic heavy metal, and greatly reduce the heavy metal risk inenvironmental, and also showed that CIT and RL2have large potential to remendiation heavymetal contamination soil.更多还原