紫花苜蓿绿色合成纳米铁及其对U(Ⅵ)去除性能的研究

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 are amorphous ellipsoid particle with particle size of 70-80 nm,and contain Fe2O3,Fe3O4,FeOOH and Fe0.In addition,ML-FeNPs are encapsulated by the organic groups of O-H,CH2,C-H,CC,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 0 mg/L,temperature of 25 ℃,reaction time of 90 min,pH of 6,dosing ratio of ML-FeNPs and U(Ⅵ) of 12.520 0 g/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.%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(ML-FeNPs),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70～80 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、CC、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 ℃、90 min、pH=6、U(Ⅵ)初始浓度10.000 0 mg/L、ML-FeNPs投加浓度12.520 0 g/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.