合成α-FeOOH形态及表面特征的研究

本文首先介绍了对Brauer方法进行修改后,用膜渗析法除去杂质,人工制备a-FeOOH(针铁矿)的过程.然后重点介绍了对合成产物的形态及表面特征的研究.研究方法主要为扫描电子显微镜法和样品在77K下对N_2物理吸附的实验.本文从扫描电子显微镜照片中得到了α-FeOOH晶体的形状和平均大小,并由此算出了单个粒子的体积和样品的比表面S_(SEM).此外,还从气固吸附实验得到了合成针铁矿的吸附等温线和脱附等温线,并据此对孔隙度进行了推断;用BET法得到了样品的比表面S_(BET).表面形态特征的研究证明,用修改后方法制备的样品不仅分散程度高,比表面大,且外形规则,均匀性好.

THE STUDY OF THE SHAPE AND SURFACE CHARACTERISTICS OF SYNTHETIC α-FeOOH

Synthetic goethite (α-FeOOH) had been prepared at the laboratory using a modified version of Brauer's method. The Process of Steam-Crystallization had been prolonged and impurities had been removed by dialysis during the preparation. The products had been characterised by X-ray Fluorescence Spectrometer, Xray Diffractometer, Surface Area Analyser and Scanning Electron Microscope. The synthetic samples prepared has given an XRD identification pattern correspoding to mineral goethite and the XRF analysis of the samples has showed no elements, other than iron, having an even minor concentration. A trace amount, less than 10 μmol/g, of chlorine had been detected only. The density of synthetic goethite as determined by Helium Displacement, is much lower than that of its naturally occurring counterpart and the products are composed of very small, cylindrically shaped particles having hemispherical ends under Scanning Electron Microscope. The BET (N_2) Specific Sueface Area of the products is much larger than that in literature. all the results mentioned above have proved that the modification of this study is successful.