缓释型保护层包覆的单分散纳米零价铁的研发及在地下水和土壤原位修复应用

Nano sized zero-valent iron (nZVI) technology, as one of the popular in-situ remediation technologies, has great potential for groundwater and soil site pollution removal. However, the industrial application of nZVI was greatly limited by rapid corrosion and poor transport performance in subsurface porous media. Various surface modification methods have been developed to improve the stability and mobility of nZVI, including polymer adsorption, solid-phase support, etc. However, few of them could facilitate the highly reactive iron to effectively transport to the target contaminated site with reactivity reserved efficiently and released purposely. Therefore, this project proposes the development of a feasible novel surface modification method, named as releasable protection shell, for mono-dispersed nZVI particles to prevent the rapid oxidation as well as aggregation, and more importantly, to ensure a good reactivity release performance towards target contaminants. The physical-chemical characteristics of coated nZVI will be analyzed to confirm fine shell formation on the surface of mono-dispersed nZVI. The anti-corrosion and dispersion enhancement capabilities of the releasable shell will be certified, and the mechanisms will be explored using AFM and EPR technologies. Furthermore, the release rate of protection shell and the reactivity of nZVI towards contaminants will be detailedly assessed. A lab-scale nZVI in-situ remediation system will be set-up to evaluate the transport and pollutant removal performance of nZVI with releasable protection shell coated. This surface modification method will potentially provide an alternative option for effective nZVI technology application in the in-situ remediation field.

纳米零价铁技术是在地下水污染和土壤污染治理领域具有广泛应用前景的原位修复技术，但是纳米零价铁的快速氧化和颗粒聚集特征直接限制了其有效的工程应用。表面包覆是常用的解决现存问题的途径，常用的方法包括聚合物吸附、固相支撑等，但现有包覆方法很难同时达到促分散、防腐蚀以及有效缓释活性零价铁的目的，以实现高迁移性的活性纳米铁到达污染区域并高效修复污染物的效果。因此，本研究拟研发一种缓释型保护层包覆的单分散纳米零价铁体系，分析包覆层对纳米零价铁的抗腐蚀性、分散稳定性以及迁移性的贡献；并进一步评估包覆层缓释速率以及在缓释后的纳米零价铁与污染物反应活性；利用现代分析技术，基于成对纳米颗粒间作用力变化理论，解释包覆层可促进纳米零价铁分散性的机制；搭建纳米零价铁在多孔介质中的原位修复模拟实验，对比零价铁和包覆后的零价铁的去除污染物效果，为缓释型保护层包覆的纳米铁的工程应用提供技术支撑。

纳米零价铁技术是在地下水污染和土壤污染治理领域具有广泛应用前景的原位修复技术，但是纳米零价铁的快速氧化和颗粒聚集特征直接限制了其有效的工程应用。表面包覆是常用的解决现存问题的途径，常用的方法包括聚合物吸附、固相支撑等，但现有包覆方法很难同时达到促分散、防腐蚀以及有效缓释活性零价铁的目的，以实现高迁移性的活性纳米铁到达污染区域并高效修复污染物的效果。因此，本研究主要研发一种缓释型保护层包覆的单分散纳米零价铁体系，验证了包覆层对纳米零价铁的抗腐蚀性、分散稳定性以及迁移性的贡献；并进一步评估包覆层缓释速率以及在缓释后的纳米零价铁与污染物反应活性；利用XPS等材料分析手段，解释零价铁抗腐蚀以及污染物去除机理；搭建纳米零价铁在多孔介质中的原位修复模拟实验，对比零价铁和包覆后的零价铁的去除污染物效果，为缓释型保护层包覆的纳米铁的工程应用提供技术支撑。