Purpose

Electrokinetic (EK) soil remediation is significantly affected by the electrode configurations. Therefore, this study was conducted to compare the performance of one-dimensional (1D) and two-dimensional (2D) arrays with respect to the remediation of heavy metal-contaminated soils.

Materials and methods

A series of laboratory-scale experiments were carried out using two types of soils: kaolinite soil (KS) artificially spiked with heavy metals (Cd, Cu, Pb, Ni, and Zn) and smelter soil (SS) contaminated with Cu and Pb, obtained near a closed smelting factory. First, stepwise experiments on the KS were conducted to compare the EK performance between the 1D and 2D electrode arrays. More specifically, the effect of the number of anode–cathode pairs was investigated in the experiments on the 1D electrode configuration, and trigonal and hexagonal arrangements were compared in the 2D EK experiments. Additionally, the performance of the trigonal array was evaluated according to changes in the anode positions, to switch the areas of effective and ineffective electric field.

Results and discussion

The removal efficiencies of the 1D electrode configuration with four anode–cathode pairs (eight electrodes in total) were 69.1% for Cd, 69.2% for Cu, 74.7% for Ni, 28.3% for Pb, and 71.3% for Zn. The removal efficiencies of the 2D hexagonal electrode array, with a similar number of electrodes (six anodes and one cathode for seven electrodes in total), were 79.8% (Cd), 82.6% (Cu), 83.7% (Ni), 34.3% (Pb), and 81.1% (Zn). The total electric power consumptions for the two types of electrode configurations were investigated to be 15.6 and 22.0 kWh/ton, respectively. Despite the increase in electric power consumption in the 2D electrode configuration, it was more efficient than the 1D configuration due to the increased area of effective (active) electric field and subsequently higher removal efficiency. As a result of changing the positions of anodes in the trigonal 2D arrangement, the removal efficiencies of Cu and Pb were increased to a level similar to that obtained with the hexagonal configuration.

Conclusions

This study demonstrated that a 2D electrode configuration increased the EK removal efficiency of contaminants compared with a 1D array. However, cost-effectiveness should be taken into account when optimizing electrode design. Furthermore, the performance of the trigonal 2D EK process was improved by changing the positions of anodes, as a result of the increase in the removal efficiency and decrease in the electrode cost and energy consumption.

中文翻译：

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电动修复重金属污染的土壤：一维和二维电极配置之间的性能比较

目的

电动（EK）土壤修复受到电极配置的影响很大。因此，本研究旨在比较一维（1D）和二维（2D）阵列在修复重金属污染土壤方面的性能。

材料和方法

使用两种类型的土壤进行了一系列实验室规模的实验：人工掺入重金属（Cd，Cu，Pb，Ni和Zn）的高岭石土壤（KS）和被Cu和Pb污染的冶炼土壤（SS），在一个封闭的冶炼厂附近获得的。首先，在KS上进行逐步实验，以比较1D和2D电极阵列之间的EK性能。更具体地说，在实验中研究了阳极-阴极对数量对一维电极配置的影响，并在二维EK实验中比较了三角形和六边形的排列。另外，根据阳极位置的变化来评估三角阵列的性能，以切换有效和无效电场的面积。

结果和讨论

具有四个阳极-阴极对（一共八个电极）的一维电极配置的去除效率对Cd为69.1％，对Cu为69.2％，对Ni为74.7％，对Pb为28.3％和对Zn为71.3％。电极数量相近的二维六边形电极阵列（六个阳极和七个阴极总共六个阳极和一个阴极）的去除效率分别为79.8％（Cd），82.6％（Cu），83.7％（Ni），34.3％ （Pb）和81.1％（Zn）。两种电极配置的总功耗分别为15.6 kWh /吨和22.0 kWh /吨。尽管2D电极配置中的功耗增加，但由于有效（活动）电场的面积增加，随后其去除效率更高，因此它比1D配置更有效。

结论

这项研究表明，与一维阵列相比，二维电极配置提高了污染物的EK去除效率。但是，在优化电极设计时应考虑成本效益。此外，由于去除效率的提高以及电极成本和能量消耗的降低，通过改变阳极的位置可以改善三角2D EK工艺的性能。