高岭土负载纳米铁在含水层的运移行为及重金属污染修复效能研究

The migration behavior and remediation efficiency of kaolin-supported zerovalent iron in aquifer

为克服重金属污染物修复过程中纳米零价铁易氧化、团聚等缺陷,本研究将其负载于高岭土表面合成负载型纳米零价铁复合材料(K-nZVI),并利用批次试验、沉降试验及模拟柱试验研究了K-nZVI在含水层中的运移行为及其对地下水重金属污染的修复效能.结果表明,K-nZVI对Pb、Cu、Cd均有很好的去除效果,去除率随着初始浓度的增加、反应温度的升高、反应时间的延长而升高,且在弱碱性条件下修复效果最好.此外,K-nZVI在含水层中表现出较好的分散和稳定性能,运移行为可通过一维对流-弥散-沉积模型描述,其运移能力随着初始浓度的增加、砂颗粒粒径的减小、地下水流速的降低和离子浓度的升高而逐渐减弱.

Supported nano-zero-valent iron composite(K-nZVI)was synthesized by coating nZVI on the surface of kaolin to avoid the defects of oxidation and agglomeration of nano-zero-valent iron(nZVI)during the process of heavy metal remediation.In this study,batch test,settlement test,and column test were respectively carried out on K-nZVI to study the remediation efficiency of heavy-metal contamination and the transport behaviors in porous media.Experimental results demonstrated that K-nZVI showed good effects on removing Pb(II),Cu(II),and Cd(Ⅱ),especially in the weak acidic condition.Also,the removing rate of K-nZVI increased with the increases of its initial concentration,the reaction temperature and the reaction time.In addition,K-nZVI presented a good dispersion and stability in aquifers,and its migration behavior could be well described by the onedimensional convection-dispersion-deposition model.The transport capacity of K-nZVI gradually reduced with the increases of its initial concentration and ion concentration,and it also decreased with the decreases of sand size and groundwater flow rate.