改进液相还原法制备纳米零价铁的研究

改进液相还原法制备纳米零价铁的研究(8700字)
摘  要：纳米零价铁颗粒具有优越的吸附性能和很高的还原活性，能有效的转化多种环境污染物，且毒副作用小，因此在环境污染的处理和环境修复领域应用广泛。本文采用一种改进液相还原法制备纳米零价铁颗粒，通过添加高分子分散剂聚乙烯吡咯烷酮（PVP）和乙醇对纳米铁颗粒进行表面物理改性，从而达到改善其在水溶液中分散性的目的。实验过程中，机械搅拌条件下，将一定浓度的NaBH4水溶液（或乙醇-水混合溶液）迅速添加到一定浓度的FeSO4•7H2O水溶液（或乙醇-水混合溶液）中，短时间即可产生大量铁粉。过程无需氮气保护，反应迅速；采用透射电子显微镜（TEM）、X射线衍射（XRD）、比表面测定仪（BET）三种方法对制得的纳米铁颗粒进行表征。结果表明：颗粒分散较均匀，粒径小，平均粒径为60nm（水溶液）和40nm（乙醇-水混合溶液），实验过程中添加的聚乙烯吡咯烷酮对颗粒的分散起到了很好的改善作用；颗粒为单质铁，没有出现氧化铁杂质、纯度高；颗粒的比表面积为47.1 m2/g（水溶液）和68.41m2/g（乙醇-水混合溶液），远高于普通铁粉的比表面积。
关键词：纳米颗粒；零价铁；液相还原；PVP；
 
Preparation of Zero Valent Iron Nanparticles by Improved Liquid Reduction
Abstract: Zero valent iron nanoparticles (NZVI) are very absorptive and also highly reductive, which can degrade various pollutants and has low toxicity. So they are widely used in the environmental restoration and the contaminants treatment.In this paper we prepare the NZVI particles with a modified method of reduction in liquid phase, in which we add polyvinlpyrrolidone (PVP) and ethanol to change the physical property of the surface of the NZVI particles in order to meliorate its dispersibility in the water solution. During the experiment, the water solution (or ethanol-water solution) of NaBH4 is added rapidly to the FeSO4•7H2O water solution (or ethanol-water solution) with the mechanical agitating. Then lots of NZVI powders are produced in a short time. The reaction is very fast and it doesn’t need the protection of N2 during the process. We adopt the transmission electron microscope (TEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) to characterize the iron particles. The results indicate that the particles disperse homogeneously with small average grain diameter of 60 nm for the water solution and 40 nm for the ethanol-water solution. The PVP added in this experiment plays an important role in the dispersibility of the NZVI particles. The particles are elementary iron with a high purity, in which there is no iron oxide. The average specific surface area of the particles is 47.1 m2/g (water solution) and 68.41 m2/g (the ethanol-water solution), which is higher than that of common iron powder.
Key  word: nanoparticles, zero valent iron; reduction in liquid phase; PVP 

目  录

摘  要：    1
关键词：    1
Abstract:    1
Key  word:    1
1 前言    2
1.1 研究背景    2
1.2 研究原理与方法    4
1.2.1 液相还原法制备纳米铁粒子的原理    4
1.2.2 纳米粒子表面改性的方法    4
1.2.3 采用PVP对纳米铁粒子进行表面改性    4
1.3 研究内容    5
2 实验部分    6
2.1仪器及试剂    6
2.2 普通液相还原制备实验    6
2.3 改进液相还原制备实验    6
3 结果与分析    7
3.1 普通液相还原制备NZVI的表征结果    7
3.2 改进液相还原制备NZVI的表征结果    8
3.2.1 PVP的添加量为0.1g/50mL    8
3.2.2 PVP的添加量为0.5g/50mL    9
3.2.3 PVP的添加量为1.0g/50mL    9
3.2.4乙醇∶水=1∶4    10
3.2.5乙醇∶水=1∶1    11
4 结论    13
参考文献    13
致    谢    13