Quantitative determination of isomorphous substitutions on clay mineral surfaces through AFM imaging: A case of mica

Abstract

In this work, a method for the quantitative determination of isomorphous substitutions on clay mineral or nanosheet surfaces has been presented in order to provide accurate, reliable and quantitative information for the isomorphous substitutions on clay mineral surfaces. It was based on the selective adsorption of a specific organic ion (benzyltrimethylammonium ions, BTMA+) on the substitution sites on clay mineral surfaces, and the atomic force microscopy (AFM) imaging of the adsorption. The adsorption behaviors of BTMA+ at the substitution sites were verified by molecular dynamic simulations. By means of an image processing software, the AFM images could be analyzed and the areas as well as area percentages of the substitution sites on the clay mineral surfaces could be determined. The case of mica, one kind of clay minerals, was showed for example in this study.