Development of Advanced In-situ Soil Remediation Method

电渗法和离子迁移法修复土壤的电动能仅限于可溶物质。在较高的pH下，土壤颗粒比较低的pH下吸附更多的重金属，如镉，并促进重金属的沉淀反应。这两种机制都使重金属无法移动，使清理变得更加困难，电动提取效率低下。因此，土壤的酸化对于提高电动法从污染土壤中清除重金属如镉的效率非常重要。同时，六价铬的流动性更强，更容易溶解。六价铬在水中具有很高的溶解性，根据溶液的pH值，它以铬酸盐、单铬酸盐或重铬酸根离子的形式存在。这种六价铬是需要修复的化学形式。在此基础上，用一种简单的电流耦合…数值方法预测了氢、镉离子在非饱和土壤中的运移。研究了更多的离子流，以及对非饱和土的处理。在这项研究中，用一种简单的数值方法预测了镉和六价铬的迁移，其中电流和水力流耦合，并在模型中诱导了土壤中的吸附过程。研究结果总结如下：与一维电极结构相比，含有三个或三个以上阳极的阴极的二维电极结构可以快速去除土壤中的镉。同时，在去除土壤中的六价铬时，与一维电极配置相比，含有三个或更多阴极的阳极的二维电极配置可以被有效地利用。较大的电极间距增加了所需的处理时间，并且还发现较大的电场强度减少了所需的处理时间。氢和镉离子在非饱和土壤中向下移动，特别是对上层砂质/粘土和下层粘土/粉质土壤的移动显著。然而，非饱和土电-水耦合坡度修复技术得到了成功的应用。较少

Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals, such as cadmium, than at a lower pH and the precipitation reactions of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient. Therefore, the acidification of soils is very important to increase the cleanup efficiencies of heavy metals, such as cadmium by electrokinetic method from contaminated soils. Meanwhile, hexavalent chromium is more mobile and easily soluble. Hexavalent chromium has high solubility in water and exists as chromate, monochromate or dichromate anions depending on the pH of the solutions. This hexavalent chromium is the chemical form requiring remediation. And then, hydrogen and cadmium ions transport in unsaturated soils are predicted with a simple numerical method in which electrical flow is coupled with hydraul … More ic flow, and the treatment for unsaturated soils are investigated. In this study, cadmium and hexavalent chromium transport are predicted with a simple numerical method in which electrical flow is coupled with hydraulic flow, and the sorption process in the soils is induced in the model. The results obtained this study are summarized as follows :The two-dimensional electrode configurations containing cathode surrounded by three or more anodes rapidly remove cadmium from soils compared with one-dimensional electrode configuration. Meanwhile, in the removal of hexavalent chromium from soils, the two-dimensional electrode configurations containing anode surrounded by three or more cathodes can be effectively utilized compared with one-dimensional electrode configuration. A larger electrode spacing increases the processing time required, and it was also found that a larger electric field strength reduced the processing time required. Hydrogen and cadmium ions move downward in unsaturated soils, particularly, move significantly downward against upper layer, sandy/clay, and lower layer, clayey/silty soils. However, remediation is applied successfully to unsaturated soils by coupled electric-hydraulic gradient. Less