Remediation of contaminated soil by the combination of supercritical fluid extraction and electrochemical reaction.

本项目的目的是开发一种超临界流体萃取和电化学反应相结合的污染土壤修复工艺。超临界流体萃取用于从污染土壤中分离有机物，电化学反应用于将萃取的有机物在有机溶剂中完全分解。考虑的有机物质是多环芳烃、多氯碳氢化合物和沥青质。我们首次开发了一种半流型超临界流体萃取器，可以在室温到750K的温度范围内使用，压力可达50兆帕。萃取器的体积约为500毫升。将被污染的土壤样本放入一个小容器中，然后放入萃取器中。利用高压柱塞泵和预热器产生高温高压水，并将预热器引入萃取器。从萃取器…排出的污水更多的人通过压力控制阀，被收集到样品校正器中。提取程序完成后，从萃取器中回收剩余样品进行分析。为了验证实验装置和实验程序，在473K和573K下测定了苯和二氯苯的溶解度。通过与苯的参考数据的比较，发现本实验方法给出了可靠的结果。下一步，我们以沥青质污染土壤作为有机土壤的模型材料。结果表明，在573K、30 Mpa的萃取条件下，沥青质可以完全分离。萃取剂由水溶组分和水不溶组分组成。采用溶剂萃取法提取水溶组分。将溶剂萃取液直接引入电化学池，通过电化学反应将萃取物完全分解，对有机化合物在水和CO2溶剂中的溶解度计算方法进行了理论研究。提出了用于超临界CO2和超临界水溶解度预测的定量结构-活度关系方程。该方程的优点之一是，计算所需的信息是分子结构数据和熔融温度。利用该方程可以定量预测二恶英在超临界流体中的溶解度。较少

The purpose of this project was to develop a remediation process of contaminated soils by the combination of the supercritical fluid extraction and electrochemical reaction. The supercritical fluid extraction functioned to separate organic materials from contaminated soil, and the electrochemical reaction was applied for the complete decomposition of the extracted organic materials in organic solvents. The organic materials considered were polyaromatic hydrocarbons, polychlorinated hydrocarbons, and asphaltens. We firstly developed a semi-flow type supercritical fluid extractor, which can be used in the temperature range from room temperature to 750 K and pressures up to 50 MPa. The volume of the extractor was about 500 cc. The contaminated soil sample was put into a small container and set in the extractor. The high temperature and high pressure water was produced with a high pressure plunger pump and pre-heater, which was introduced into the extractor. The effluent from the extractor … More went through the pressure control valve and was collected into a sample corrector. After the extraction procedures, the remained sample was recovered from the extractor for analysis. In order to check the experimental apparatus and procedures, the solubility of benzene and dichlorobenzene were measured at 473 K and 573 K.From the comparison with the reference data of benzene, it was found that the present experimental procedure gives reliable results. In the next step, we used asphalten contaminated soil as the model materials of organic containing soil. It was found that the asphaltene can be separated completely by the extraction at 573 K and 30 MPa. The extractants were consisted from water soluble and water insoluble fractions. The water soluble fractions were extracted with solvent extraction. The solution obtained from the solvent extraction was introduced into the electrochemical cell directly, and the extracted organic materials were decomposed completely by the electrochemical reactions.The theoretical study to investigate the solubility calculation method for the organic compounds in water and CO2 solvents was investigated. The quantitative structure and activity relationship equation was proposed for the solubility prediction for the supercritical CO2 and supercritical water. One of the advantages of this equation was that the information needed for the calculation is molecular structural data and melting temperature. With this equation, we can predict the solubility of dioxins in supercritical fluids quantitatively. Less