Li Dong, Sun Delin, Hu Siyang, Hu Jing, Yuan Xingzhong
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, PR China; Key Laboratory of Southwest Resources Exploitation and Environmental Hazards Controlling Engineering of Education Ministry, Chongqing University, Chongqing 400030, PR China; School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
Chemosphere. 2016 Feb;144:1823-30. doi: 10.1016/j.chemosphere.2015.09.077. Epub 2015 Nov 11.
A conceptual design and experiments, electrochemistry-flushing (E-flushing), using electrochemistry to enhance flushing efficiency for the remediation of Cr(Ⅵ)-contaminated soil is presented. The rector contained three compartments vertically superposed. The upper was airtight cathode compartment containing an iron-cathode. The middle was soil layer. The bottom was anode compartment containing an iron-anode and connected to a container by circulation pumps. H2 and OH(-) ions were produced at cathode. H2 increased the gas pressure in cathode compartment and drove flushing solution into soil layer forming flushing process. OH(-) ions entered into soil layer by eletromigration and hydraulic flow to enhance the desorption of Cr(Ⅵ). High potential gradient was applied to accelerate the electromigration of desorbed Cr(Ⅵ) ions and produced joule heat to increase soil temperature to enhance Cr(Ⅵ) desorption. In anode compartment, Fe(2+) ions produced at iron-anode reduced the desorbed Cr(Ⅵ) into Cr(3+) ions, which reacted with OH(-) ions forming Cr(OH)3. Experimental results show that Cr(Ⅵ) removal efficiency of E-flushing experiments was more than double of flushing experiments and reached the maximum of removal efficiency determined by desorption kinetics. All electrochemistry processes were positively used in E-flushing technology.
本文介绍了一种概念设计及实验——电化学冲洗（E冲洗），即利用电化学方法提高冲洗效率，以修复铬（Ⅵ）污染土壤。反应器垂直叠加有三个隔层。上层是气密的阴极隔层，包含一个铁阴极。中间是土壤层。下层是阳极隔层，包含一个铁阳极，并通过循环泵与一个容器相连。在阴极产生氢气和氢氧根离子。氢气增加了阴极隔层中的气压，并将冲洗液驱入土壤层形成冲洗过程。氢氧根离子通过电迁移和水力流动进入土壤层，以增强铬（Ⅵ）的解吸。施加高电位梯度以加速解吸的铬（Ⅵ）离子的电迁移，并产生焦耳热以提高土壤温度，从而增强铬（Ⅵ）的解吸。在阳极隔层中，铁阳极产生的亚铁离子将解吸的铬（Ⅵ）还原为铬（Ⅲ）离子，其与氢氧根离子反应形成氢氧化铬。实验结果表明，E冲洗实验中铬（Ⅵ）的去除效率是冲洗实验的两倍多，且达到了解吸动力学确定的去除效率最大值。所有电化学过程在E冲洗技术中都得到了积极应用。
