改进液相还原法制备纳米零价铁颗粒  

Preparation of Nano Zero-valent Iron Particles by Modified Liquid Phase Reduction Method

作　　者：高树梅[1] 王晓栋[1] 秦良[1] 罗斯[1] 赵欣[1] 刘树深[2] 王连生[1] 

机构地区：[1]污染控制与资源化研究国家重点实验室,南京大学环境学院,南京210093 [2]长江水环境教育部重点实验室,同济大学环境科学与工程学院,上海200092

出　　处：《南京大学学报（自然科学版）》2007年第4期358-364,共7页Journal of Nanjing University（Natural Science）

基　　金：江苏省自然科学基金创新人才项目(BK200418);国家自然科学基金(20507008;20477018);国家973项目(2003CB415002)

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,因此在环境污染的处理和环境修复领域应用广泛.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.TEM表征的结果表明：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,其机理主要是通过分散剂吸附改变粒子的表面电荷分布,产生静电稳定效应,空间位阻作用和静电空间位阻稳定效应来达到分散效果;加入乙醇后,可能是由于乙醇中包含大量的自由的强极性羟基基团,在水溶液中这些基团与金属离子之间形成螯合键,紧密包覆在金属离子周围,形成一个有限制形状的有限结构,使合成的纳米粒子的大小被限制,从而达到改性的目的.XRD表征的结果表明：在扫描衍射角度（2θ）为30°-100°时,出现衍射峰时对应的2θ分别为45°、65°、82°左右,对照铁的标准PDF卡片发现,刚好对应相应的110晶面衍射（44.6732°）,200晶面衍射（65.0211°）,211晶面衍射（82.3326°）,同时通过布拉格方程及电子衍射花样的分析,均表明颗粒为单质铁,没有出现氧化铁杂质、纯度高.采用BET表征的结果表明：颗粒的比表面积为47.1m^2/g（水溶液）和68.41m^2/g（乙醇—水混合溶液）,远远高于普通铁粉的比表面积.多次试验的�Nano zero-valent iron particles are very absorptive and also highly reductive. So they are widely used in the environmental restoration and the treatment of the environmental contaminants. In this paper we prepare the nano zero-valent iron particles with a modified method of reduction in liquid phase, in which we add polyvinlpyrrolidone （k30） （which is a kind of macromolecule of dispersant） and ethanol to change the physical property of the surface of the nano zero-valent iron particles in order to meliorate its dispersibility in the water solution. In the experiment of this study, the water solution （or ethanol-water solution） of NaBH4 of a certain concentration is added to the water solution （or ethanol-water solution） of FeSO4 · 7H2O of a certain concentration rapidly with the mechanical agitating, and then lots of iron powder is produced in a short time. The reaction is very fast and it doesn＇t need the protection of N2 in the process. We adopt the transmission electron microscope （TEM）, X-ray diffraction （XRD） and Brunauer Emmett Teller （BET） to characterize the iron particles. The result of the TEM indicates that the particles are dispersed homogeneously with small average grain diameter of 60 nm for the water solution and 40 nm for the ethanol-water solution. The polyvinlpnolidone（k30） added in this experiment plays a very important role in the dispersibility of the nano iron particles by changing the charge distribution of the surface and then generating the effect of electrostatic stabilizing, space steric and electrostatic space steric stabilizing. When ethanol is added in, the size of the nano particles is limited and a limiting framework is consequently formed. Perhaps there are many free and strong polar hydroxyl groups in the ethanol, and in the water solution these groups chelate to the metallic ions and then cover them tightly. The result of the XRD shows that when the scan angle（20） ranges from 30° to 100°, the corresponding 20 where the diffraction peak a

关 键 词：纳米 零价铁颗粒 制备 液相还原法 

分 类 号：TM27[一般工业技术—材料科学与工程]