Sayed Hassan Malak, Villieras Frédéric, Gaboriaud Fabien, Razafitianamaharavo Angelina
Laboratoire Environnement et Minéralurgie (LEM), UMR 7569 INPL & CNRS, Ecole Nationale Supérieure de Géologie, BP 40, 54501 Vandoeuvre-lès-Nancy, France.
J Colloid Interface Sci. 2006 Apr 15;296(2):614-23. doi: 10.1016/j.jcis.2005.09.028. Epub 2005 Oct 17.
The distribution of edge and basal surface areas of phyllosilicate particles is an essential parameter for understanding the interaction mechanisms at solid/gas or solid/liquid interfaces. Among the techniques proposed to determine the geometrical heterogeneities of flat solids, low-pressure argon adsorption and AFM analysis are the most promising to derive the weight-averaged values of specific surface areas. A series of publications have recently been dedicated to the combination of both methods showing the correlation between the two approaches. As obtaining a large set of high-resolution AFM images is time-consuming, it is necessary to test the ability of AFM routine analysis to derive surface areas and aspect ratio systematically and statistically, with all possible experimental and instrumental artefacts. In the present study, the expected agreement was found between AFM and argon adsorption determination for total, basal, and edge-specific surface areas of nonswelling clay minerals, except for one kaolinite, which is very heterogeneous in size. In addition, it was observed that for a given sample, individual particles present similar shapes, whatever their size, making it possible to derive a statistical relationship between AFM basal and total surface areas. On the basis of the obtained results, recommendations are given to derive accurate edge, basal, and total specific surface areas of phyllosilicates by combining conventional gas adsorption (nitrogen BET) and routine AFM techniques.
层状硅酸盐颗粒边缘和基面面积的分布是理解固/气或固/液界面相互作用机制的一个重要参数。在为确定扁平固体几何不均匀性而提出的技术中，低压氩吸附和原子力显微镜（AFM）分析是最有希望得出比表面积加权平均值的方法。最近有一系列出版物致力于将这两种方法结合起来，展示了两种方法之间的相关性。由于获取大量高分辨率AFM图像很耗时，因此有必要系统地、统计地测试AFM常规分析得出表面积和纵横比的能力，同时考虑所有可能的实验和仪器假象。在本研究中，除了一种粒径非常不均匀的高岭土外，对于非膨胀性粘土矿物的总、基面和边缘比表面积，AFM测定和氩吸附测定之间达成了预期的一致性。此外，还观察到对于给定的样品，无论颗粒大小如何，单个颗粒都呈现相似的形状，这使得能够得出AFM基面面积和总表面积之间的统计关系。基于所得结果，给出了通过结合传统气体吸附（氮气BET）和常规AFM技术得出层状硅酸盐准确的边缘、基面和总比表面积的建议。
