电场驱动纳米Fe0在不同介质中的迁移行为研究

选取四种不同介质(100%石英砂、75%石英砂/25%高岭土、50%石英砂/50%高岭土和100%高岭土),探讨了黄原胶分散的纳米Fe~0在不同介质中的迁移行为。纳米材料投加点设置在介质填充池中间靠近阳极电解池的位置。研究发现,采用该实验装置,100%石英砂的处理中电渗流量最大,这与其较大的孔隙和渗透性有关,加入高岭土的处理中电渗流量较小且各处理流量相当。纳米Fe~0在石英砂中的迁移高于加入高岭土的处理,大部分纳米Fe~0集聚在靠近投加口的部分,在远离投加口的部分铁逐渐由Fe2+向Fe3+转化。100%高岭土中纳米Fe~0的迁移高于混合介质处理,这与其较高的电流强度有关。纳米Fe~0在电动迁移过程中很容易发生溶解和转化,其在高岭土中的迁移是以离子态进行的。μ-XANES(微束X射线近边分析)的分析结果证实电场驱动下高岭土中的铁主要以纤铁矿和磁铁矿形式存在。

The transport behavior of nano Fe0 in different mediums under electrical field

Nano zero-valent iron(nano Fe0)has attracted increasing attention for the remediation of contaminated groundwater and soil due to its high surface area and chemical reactivity. However, the transport of nano Fe0 is usually limited or halted by its aggregation and settling in the soil pores. Coupling with electrokinetics(EK)would enhance the delivery of nano Fe0, especially in the low-permeability subsurface. In this study, four different mediums(100%silica sand, 75%silica sand/25%kaoline, 50%silica sand/50% kaoline and 100%kaoline) were selected as typical mediums, and the effect of EK on the transportation behavior of dispersed nano Fe0 in different mediums was evalu-ated. The injection spot of nanoparticles was located about 3 cm from the anode compartment. The result showed that the transport of dis-persed nano Fe0 is more obvious in 100%sand than that in the other mediums with EK, which was related to the higher electroosmotic flow due to the higher porosity. Most of the nano Fe0 was retained in the location near the injection spot and gradually dissolved into Fe2+and Fe3+in S3 and S4 section. The transportation of nano Fe0 in 100%kaoline was higher than the other mixed mediums, which was attributed to its higher electrical current. Nano Fe0 migrated in kaoline is existed as lepidocrocite and magnetite according toμ-XANES analysis, which in-dicated that the dissolution and transformation of nano Fe0 was easy to occur during EK delivery process and its migration in kaoline was carried out in ionic state.