中文摘要：

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。本文利用紫花苜蓿（Medicago sativa L.）还原制备绿色纳米铁颗粒（MLFeNPs）,采用紫外可见分光光度计、X射线粉末衍射仪、扫描电子显微镜、透射电子显微镜、能谱仪、傅里叶变换红外光谱等方法对ML-FeNPs进行表征。结果表明：制备的ML-FeNPs为无定形的椭球形颗粒,粒径为70～80nm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。ML-FeNPs对U（Ⅵ）去除性能的研究表明,在25℃、90min、pH=6、U（Ⅵ）初始浓度10.000 0mg/L、ML-FeNPs投加浓度12.520 0g/L条件下,U（Ⅵ）去除率达到88.90%。ML-FeNPs对U（Ⅵ）的去除主要发生在颗粒表面,去除机理为还原、吸附、络合共同作用,且其表面的有机基团能促进对U（Ⅵ）的去除。

英文摘要：

Green synthesis of metallic nanoparticles is a promising field of research in recent years.It has been proved that the simple and cost-effective green synthesis process is environmentally friendly,stable and can be used for large-scale production.In this study,iron nanoparticles（ML-FeNPs）were synthesized using aqueous Medicago sativa L.extracts as both the reducing and capping agent.ML-FeNPs was analyzed by UV-Vis,XRD,SEM,TEM,FTIR and EDX techniques.The prepared ML-FeNPs areamorphous ellipsoid particle with particle size of 70-80 nm,and contain Fe2O3,Fe3O4,FeOOH and Fe～0.In addition,ML-FeNPs are encapsulated by the organic groups of O—H,CH2,C—H,C—C,C—N,C—O—C.The removal of U（Ⅵ）from aqueous solution by ML-FeNPs was also investigated.The optimum removal conditions are as follows：Initial U（Ⅵ）concentration of 10.000 0mg/L,temperature of 25 ℃,reaction time of 90 min,pH of 6,dosing ratio of ML-FeNPs and U（Ⅵ）of 12.520 0g/L.At this condition,the removal rate of U（Ⅵ）can reach 88.90% by ML-FeNPs.The removal of U（Ⅵ）mainly takes place in the surface of ML-FeNPs,the plausible mechanism for the removal of U（Ⅵ）using ML-FeNPs is the combined action of reduction,adsorption and complexation,and the removal of U（Ⅵ）is improved by the organic groups.