仿真土壤孔隙中铁基修复材料迁移行为及其与砷的稳定化反应机制

Adsorption and co-precipitation are two principal removal mechanisms involved in stabilization of arsenic (As) in soil with iron-based remedial materials. Soils are structured media having a multitude of pore-domains that result in soil pore is one of the most important locations for the reaction between iron-based materials and As, while the pore scale mechanism has not been well understood. This proposed study intends to establish an observation platform of physical simulation test for soil pores, including micro-model chip system, combined flow reactor and synthetic aggregate, finite element analysis technique, and so on. Three representative iron-based materials, nanoscale zero-valent iron (nZVI), Fe3O4, and Fe-Mn binary oxide will be tested in the study. First, transport characteristic of iron-based materials in the synthetic soil pores (the mean pore sizes are 250, 75, and 30 μm) will be observed in real time by epifluorescent microscope and reflected differential interference contrast microscopy. Second, the effect of environment conditions (such as pH, Eh, competitive ions on the reaction process between iron-based materials and As will be revealed by spectroscopy technologies (such as IR, XPS, XAS, and so on). Third, the transport process of iron based materials in the complex flow field at micro scale will be simulated with finite element method. Furthermore, the findings obtained from the mimic soils will be test and verify in practice. The research results may further enrich the theory of soil remediation at micro scale, and provide scientific support for the development of As stabilization technology.

铁基材料可通过吸附或共沉淀方式与砷进行稳定化反应，达到治理砷污染土壤的目的。土壤孔隙是铁基修复材料与砷发生反应的重要场所之一，但是探明孔隙尺度下土壤铁砷反应机制一直是研究难点。本研究拟建立土壤孔隙物理仿真实验观测平台，具体包括微流控芯片实验系统、人工合成土壤多孔结构实验系统和有限元分析技术等。以纳米零价铁、四氧化三铁和铁锰双金属氧化物等3种代表性的铁基修复材料为主要研究对象，应用上述平台，借助落射荧光显微镜和微分干涉差显微镜等，实时观测铁基材料在仿真土壤孔隙（平均孔径分别为250，75和30 μm）中的迁移行为；揭示在pH、Eh和竞争离子等环境因素影响下，铁基材料在孔隙尺度下与砷的反应过程；应用有限元技术对微尺度下复杂流场中铁基材料的迁移反应过程进行模拟，并开展实际砷污染土壤稳定化试验进行验证。研究成果可丰富与完善微观尺度下土壤修复原理，为发展稳定化技术提供科学支撑。

铁基材料可通过吸附或共沉淀方式与砷进行稳定化反应，达到治理砷污染土壤的目的。土壤孔隙是铁基修复材料与砷发生反应的重要场所之一，但是探明孔隙尺度下土壤铁砷反应机制一直是研究难点。本研究建立了土壤孔隙的物理仿真实验观测平台，具体包括微流控芯片实验系统、人工合成土壤多孔结构实验系统和有限元分析技术等。以铁铈氧化物、铁基氧化物和铁锰双金属氧化物等3种代表性的铁基修复材料为主要研究对象，应用上述平台，借助落射荧光显微镜和微分干涉差显微镜等，实时观测铁基材料在仿真土壤孔隙（平均孔径分别为250，75和30 μm）中的迁移行为；揭示在pH、Eh和竞争离子等环境因素影响下，铁基材料在孔隙尺度下与砷的反应过程；应用有限元技术对微尺度下复杂流场中铁基材料的迁移反应过程进行模拟，并开展实际砷污染土壤稳定化试验进行验证。研究成果丰富与完善了微观尺度下土壤修复原理，为发展稳定化技术提供科学支撑。