电极材料对电渗过程作用机理的试验研究

分别采用铁、石墨、铜和铝电极开展室内电渗试验,从宏观和微观层面对试验结果进行分析,比较电势损失和离子迁移过程对电渗效果的贡献,并基于微观机理对电渗宏观规律作出合理解释.Fe2+和Cu2+迁移能力较差,大多聚集在阳极附近无法移动,Al3+迁移能力较强,在电场作用下易运移到阴极随水排出；电极材料通过电极反应生成离子进入土壤对电渗的促进甚小,其主要作用在于通过电极腐蚀、钝化、氧化以及电极与土体部分脱离引起电势损失,这是不同电极材料电渗效果差异的根本原因,同时表明电渗排水依赖于土壤中其他离子类型；电能利用率与土体本身性质密切相关,受电极材料影响不大.该研究可进一步揭示电渗机理,为电渗法的工程应用提供指导.

Experimental study on function mechanism of electrode materials upon electro-osmotic process

Laboratory electro-osmotic tests using ferrum, graphite, copper and aluminum electrodes were conducted to investigate the impact of electrode materials upon electro-osmotic effect. Contributions of voltage loss and ion migration process to the electro-osmotic effect were compared. Interpretations of macroscopic consequences from the perspective of microscopic mechanism are also presented. Massive accumulations of Fe2+ and Cu2+ are detected in the vicinity of the anode, while Al3+ can easily transport to the cathode and discharge together with water, which demonstrates better migrational ability of Al3+ over Fe2+ and Cu2+. It is revealed that considerable variations of electro-osmotic effect among different electrode materials mainly come from voltage loss, which is a combined result of erosion, passivation and oxidation of electrode and the departure with soil mass, rather than the migrational ability of the ions from electrode reactions. The results indicate the dependency of electro-osmotic dewatering upon ions in the soil. It is also found that electrode materials barely occupy any impact on the energy utilization ratio, which is closely related to properties of the soil. The results achieved can further uncover the mechanism of electro-osmosis as well as provide guidelines for engineering applications of the electro-osmosis technique．