微波辅助植物原位还原组装Fe@AlSi纳米材料及其固定铀酰离子机制

With the rapid deveoplent of nuclear power in China, there will be a great deal of radioactive contamination on the groundwater during the process of uranium mining and metallurgy. Because of the migration of uranyl ion, the ecological potential risks are increasing. Nanoscale zerovalent iron particles have been proposed as a new generation of material for remediation of radionuclides-polluted groundwater, especially for immobilization of uranium. In this project, iron ion encapsulated aluminosilicate, designated as Fe@AlSi, will be prepared through microwave assisted in situ nucleation and growth using plant extracts as reducing agent, capping agent and uranium binding agent. Alfalfa, sunflower and tea, characterized in high uranium enrichment, are chosen in this green synthesis. The nanoparticle of Fe@AlSi will be employed to treat uranium-bearing groundwater in uranium mine and prevent its further migration and spread through the deep subsurface. The theoretical research on the preparation and application of Fe@AlSi, particularly the action mechanism of biomass in plant-mediated synthesis, the growth features of nano iron in AlSi matrix and the performance and mechanism of uranium removal by Fe@AlSi, will also be explored in this project. Based on the achievements of the project, the theoretical foundation of plant-mediated synthesis of nanomaterials and a new function material for remediation of radioactive contamination of groundwater will be provided.

在核资源开发的同时，铀矿冶过程产生了大量地下水放射性污染，因铀酰离子的迁移性，可产生更大范围的危害。纳米零价铁是一种很有潜力的铀污染治理材料，其关键在于对铀的固定性能。本项目以对铀具有高富集性的植物紫花苜宿、向日葵、茶的提取液作为还原剂、包裹剂和铀结合剂，以蒙脱石骨架AlSi微粒为载体，辅以微波辐射，将铁离子原位还原成纳米零价铁镶嵌到AlSi夹层中，制备具有高效铀酰离子固定性能的Fe@AlSi纳米材料，并应用于铀污染地下水的修复。拟探讨植物生物质在制备纳米零价铁中的作用机制，阐明铁离子在AlSi微粒上的组装途径，并考察Fe@AlSi对铀酰离子固定的性能和机理。旨在完善植物还原法制备纳米材料的理论，为铀矿采冶区放射性污染地下水的修复提供新的功能材料，具有重要的学术价值和广阔的应用前景。

铀矿资源在开放利用的过程中，周边地区土壤、地表水、地下水等会受到放射性物质（铀酰离子等）的污染。植物还原制备绿色纳米金属材料因环境友好、反应条件温和、可持续发展、可控等优势成为纳米材料合成领域的研究热点。本项目采用黑茶、紫花苜蓿的提取液作为还原剂、包裹剂和铀结合剂还原Fe（III）、Fe（II）制备绿色纳米零价铁颗粒（BT-FeNPs/ATP、ML-FeNPs），以及绿色纳米零价铁/凹凸棒（BT-FeNPs/ATP）。制备的纳米铁材料为无定形的椭球形颗粒，粒径为70 ~ 200 nm左右，纳米颗粒中的铁主要以Fe2O3、Fe3O4、FeOOH及Fe0形式存在，颗粒表面包裹-O-H、-CH2、-C-H、-C=C、-C-N、-C-O-C等有机基团。在不同环境条件下绿色纳米零价铁颗粒主要通过吸附、还原、络合等作用将溶液中U(VI)、Cr（VI）、Pb（II）去除。针对铀矿冶地域周边低放土壤的植物修复问题，研究了黑麦草在不同铀胁迫下的生长响应、抗氧化体系酶活性的变化及对铀的积累特征。本研究为铀矿采冶区放射性污染地下水的修复提供新的功能材料，具有重要的学术价值和广阔的应用前景。