Ng Yee-Sern, Sen Gupta Bhaskar, Hashim Mohd Ali
Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603, Kuala Lumpur, Malaysia.
Water Academy, School of the Built Environment, Heriot-Watt University, Edinburgh Campus, EH14 4AS, Scotland, UK.
Environ Sci Pollut Res Int. 2016 Jan;23(1):546-55. doi: 10.1007/s11356-015-5290-0. Epub 2015 Sep 2.
Electrokinetic process has emerged as an important tool for remediating heavy metal-contaminated soil. The process can concentrate heavy metals into smaller soil volume even in the absence of hydraulic flow. This makes it an attractive soil pre-treatment method before other remediation techniques are applied such that the chemical consumption in the latter stage can be reduced. The present study evaluates the feasibility of electrokinetic process in concentrating lead (Pb) and chromium (Cr) in a co-contaminated soil using different types of wetting agents, namely 0.01 M NaNO3, 0.1 M citric acid and 0.1 M EDTA. The data obtained showed that NaNO3 and citric acid resulted in poor Pb electromigration in this study. As for Cr migration, these agents were also found to give lower electromigration rate especially at low pH region as a result of Cr(VI) adsorption and possible reduction into Cr(III). In contrast, EDTA emerged as the best wetting agent in this study as it formed water-soluble anionic complexes with both Pb and Cr. This provided effective one-way electromigration towards the anode for both ions, and they were accumulated into smaller soil volume with an enrichment ratio of 1.55-1.82. A further study on the application of approaching cathode in EDTA test showed that soil alkalisation was achieved, but this did not provide significant enhancement on electromigration for Pb and Cr. Nevertheless, the power consumption for electrokinetic process was decreased by 22.5%.
电动修复技术已成为修复重金属污染土壤的一种重要工具。即使在没有水力流动的情况下，该技术也能将重金属浓缩到更小的土壤体积中。这使其成为在应用其他修复技术之前一种有吸引力的土壤预处理方法，从而可以减少后期的化学药剂消耗。本研究评估了使用不同类型的湿润剂，即0.01M硝酸钠、0.1M柠檬酸和0.1M乙二胺四乙酸（EDTA），通过电动修复技术在共污染土壤中富集铅（Pb）和铬（Cr）的可行性。所获得的数据表明，在本研究中硝酸钠和柠檬酸导致铅的电迁移效果不佳。至于铬的迁移，由于铬（VI）的吸附以及可能还原为铬（III），这些试剂在低pH值区域也表现出较低的电迁移速率。相比之下，EDTA在本研究中是最佳的湿润剂，因为它与铅和铬都形成了水溶性阴离子络合物。这为两种离子提供了有效的单向阳极电迁移，并且它们被富集到更小的土壤体积中，富集比为1.55 - 1.82。对EDTA试验中靠近阴极应用的进一步研究表明，实现了土壤碱化，但这并未显著增强铅和铬的电迁移。尽管如此，电动修复过程的耗电量降低了22.5%。
