利用纳米铁还原固定土壤中铼的机理研究

【作者】 王雪；

【导师】 钱天伟；

【作者基本信息】 太原科技大学 ， 流体力学， 2010， 硕士

【摘要】 为严重的环境危害,但是采用常用的吸附等方法却很难将其固定,因此本工作的目的是研究零价纳米铁还原固定锝的方法及其机理。鉴于非放射性元素铼与锝的物理化学性质相似,故本文实验选用元素铼替代锝,在利用纳米铁还原固定铼的实验基础上对其反应结果和机理进行分析和探讨,为进一步深入了解整个反应的本质提供了理论和实践依据。本文首先介绍了纳米铁粉的发展历史和典型的制备方法,同时研究了实验室液相还原法制备零价纳米铁微粒过程及在反应体系中添加表面活性剂所产生的影响,并利用激光粒度仪（LS）、X射线粉末衍射仪（XRD）、扫描电镜（SEM）等分析手段进行了全面表征,得到了具有实用性的稳定纳米铁粉。之后,在土壤介质中,利用所制得的稳定纳米铁粉还原高铼酸钾。以批实验和柱实验的形式,通过分光光度法进行测量和分析,定量计算出在不同反应时间和不同ReO₄^-离子初始浓度条件下纳米铁粉对ReO₄^-离子的去除率。在实验的基础上进行拟一级反应动力学拟合,并研究淀粉投加量、纳米铁微粒的投加量、ReO₄^-离子的初始浓度、表面活性剂溶液的初始pH值以及温度对反应的影响。通过本研究工作可得到结论,实验室自制的稳化高效纳米铁粉对土壤中ReO₄^-离子的还原固定效果十分理想,经计算拟合可知该反应符合准一级反应动力学。更多还原

【Abstract】 As a radioactive element, Technetium is of a long half-life period and complicated chemical behavior, whose oxide-the TcO₄^- ion- endangers the environment horribly by easy transference. However, it is hard to fix the TcO4- ion through regular absorption methods. Hence, this assignment focuses on the methods of reduction that nanometer iron acts on the technetium,as well as the mechanism for the utter destination. Since the physiochemical properties of both Rhenium, which is a non radioactive element and Technetium are the same nearly, it is reasonable to displace technetium with rhenium for text object. Besides, on the base of the reduction, its results and mechanism will be analyzed and argued in this thesis. All the work above helps master the reacting essence theoretically and practically.This thesis firstly introduces the development history and classical preparing methods of nanometer iron powder, furthermore studies the influences from adding surfactants into the reacting system during which, named liquid phase reduction in the laboratory, prepares the zero valence nanometer iron particles, and concurrently finishes the corresponding characterization by apparatus, such as LS, XRD, SEM and etc. Finally, the stabile nanometer iron powder of application is attained. Then within the soil as media, stabile nanometer iron powder prepared already is used to restore the potassium per-rhenium. The removal rate of the ReO₄^- ion is calculated quantitatively in the way of batch text and pillar text under different reacting time and different initial concentrations of the ReO₄^- ion, after being measured and analyzed through spectrophotometry. In the last, it is needed to fit the hypothetical first grade reaction kinetics on the foundation of experiment, and observe the reacting influence of starch quantity added, nanometer iron particles quantity added, initial concentration of ReO₄^- ion, initial pH value of surfactant solution and the temperature.Therefore, the conclusion from this study is drawn up, which is that the relatively sound effect of both restore and reduction comes from the experiment carried out on the ReO₄^- ion in soil, using the stabile effective nanometer iron powder prepared myself in laboratory, in addition, this reaction is accordant with the standard first grade reaction kinetics.更多还原