改性纳米零价铁对污染土壤中重金属的稳定化效率和机制

As a potential environmental remediation material, the study and use of nano-sized zero-valent iron (nZVI) and its modified forms have been a hotspot in the remediation field. However, few studies have focused on the stabilization heavy metal polluted soil by nZVI, especially the modified nZVI. And moreover the stabilization mechanism is still not clear. In the present project, we choose three stabilizers of different properties, sodium dodecylsulfate, polyvinylpyrrolidone, carboxymethyl cellulose, to modify nZVI. The the stability and mobility of modified nZVI and in different polluted soils will be studied tod investigate the different properties of modified nZVI . Several methods including diffusive gradients in thin-films (DGT), toxicity characteristic leaching procedure (TCLP) and in vitro physiologically based extraction test (PBET) will be used to study the stabilzation efficiency of heavy metalby three modified nZVI. In addition, triditional sequential extration method and X-ray powder diffraction, X-ray photoelectron spectroscopy, X-ray absorption near edge spectroscopy will be used to study the changes of Zn, Cd, As, Pb fractions and binding in polluted soils to deeply investigate the stabilization mechanisms of heavy metals in polluted soils by three modified nZVI. The project will provide scientific basis for the stabilization heavy metals in polluted soils by modified nZVI.

作为一种很有潜力的修复材料，纳米零价铁及其改性已成为环境修复领域的研究热点，但利用纳米零价铁特别是改性纳米零价铁对重金属污染土壤进行稳定化修复的研究甚少，对其稳定机制尚不清楚。本项目拟以不同性质的稳定剂,十二烷基硫酸钠，聚乙烯吡咯烷酮以及羧甲基纤维素改性的纳米零价铁为研究对象，研究改性纳米零价铁自身及在不同污染土壤中的稳定性和迁移性，阐明稳定剂性质的不同对改性后纳米零价铁性质的变化。用现代薄层凝胶梯度法、毒性浸出法、体外模拟生理原理提取法等评价方法，研究不同改性纳米零价铁对不同类型污染土壤中重金属的稳定化效率，同时利用传统连续提取方法以及X射线光电子能谱、X射线衍射、X射线吸收近边结构谱等技术研究改性纳米零价铁稳定化后土壤中锌、镉、砷、铅重金属形态和结合的变化，深入探索改性纳米零价铁对不同类型污染土壤中金属的稳定机制，为改性纳米零价铁稳定化重金属污染土壤提供理论基础。

作为一种很有潜力的修复材料，纳米零价铁及其改性已成为环境修复领域的研究热点，但利用纳米零价铁特别是改性纳米零价铁对重金属污染土壤进行稳定化修复的研究甚少，对其稳定机制尚不清楚。本项目调查并采集了南方、长江中下游、西北典型的重金属复合污染农田土壤，分析了不同重金属复合污染农田土壤的土壤理化性质和重金属含量。制备了十二烷基硫酸钠（SDS）（阴离子型表面活性剂）、聚乙烯吡咯烷酮以及羧甲基纤维素（CMC）改性的纳米零价铁，进行了改性前后纳米零价铁的形态表征。深入研究了SDS、PVP以及CMC改性的纳米零价铁以及未改性的纳米零价铁在三种不同性质土壤中的迁移性和稳定性。通过批量吸附解析实验，研究了不同性质土壤对不同改性前后的纳米零价铁的吸附解析动力学，探讨了土壤性质以及改性剂对纳米零价铁在土壤中迁移性和稳定性的影响机理。利用浸出毒性法（TCLP），研究了改性纳米零价铁对三种不同污染土壤中不同重金属的稳定效率。利用化学提取法，对不同改性纳米零价铁稳定化后的不同土壤中的不同粒级的土壤颗粒，进行五步连续提取，研究了五种形态重金属含量的变化，揭示稳定化后，土壤中重金属形态和结合状态的变化情况，分析并探讨了不同改性纳米零价铁对污染土壤中重金属的稳定机制，为改性纳米零价铁稳定化重金属污染土壤提供理论基础。