土壤中2,4-二氯酚在非均匀电动力学作用下的迁移

Mobilization of 2,4-dichlorophenol in soils by non-uniform electrokinetics

研究了土壤中的2,4 二氯酚(2,4 DCP)在非均匀电动力学作用下的迁移特征和影响因素,揭示利用非均匀电动力学技术修复2,4 DCP污染土壤的特性.结果表明,非均匀电动力学过程能有效地促进土壤中2,4 DCP的解吸和迁移,其作用效果与土壤性质、电极反应和运行方式等密切相关.土壤pH较高时,2,4 DCP主要通过电迁移向阳极运动,向阴极的电渗析作用影响较小.电极反应影响土壤pH和2,4 DCP的离解,使2,4 DCP的迁移随时间而变化,其变化程度与土壤酸碱缓冲能力和Zeta电位密切相关.采用适当的运行方式可以控制土壤中2,4 DCP的运移.

Non-uniform electrokinetic remediation is a promising technology under development. It does not disturb the natural environment during remediation and save energy at the same time. In this study, the mobilization and its affecting factors of 2,4-dichlorophenol (2,4-DCP) in sandy loam soil and light clay by non-uniform electrokinetics was investigated, through bench-scale experiments, to assess the feasibility of using non-uniform electrokinetic technology to remediate 2,4-DCP-contaminated soils. The results showed that non-uniform electrokinetic transport processes can effectively stimulate the desorption and movement of 2,4-DCP in the tested soils, depending upon the soil characteristics, the electrolysis reaction on electrodes and the operation mode. The movement of 2,4-DCP in the sandy loam towards the anode was about 1.0?cm·d^(-1) under a potential gradient of 1.0?V·cm^(-1), about 1.0～1.5?cm·d^(-1) slower than that in the light clay. Electromigration and electroosmotic flow were the main driving forces for the movement of 2,4-DCP, but electromigration played a predominant role in the mobilization, especially under higher pH condition or over extended treatment time. When the sandy loam was adjusted to pH 9.3, the movement of 2,4-DCP towards the anode was about five times greater than that at pH 7.7. Electrolysis of pore fluids on electrodes influenced soil pH and the ionization of 2,4-DCP, and induced the changes in the mobilization of 2,4-DCP, depending upon the acid-base buffering capacity and zeta potential of the tested soils. In addition, the movement of 2,4-DCP in the soils can be regulated by the operation mode. It is believed that non-uniform electrokinetics has the potential for practical application in the remediation of 2,4-DCP contaminated soils.