Study of different sample preparation methods for SEM micrographs from heavy metal-contaminated illite and kaolinite

The soil properties are function of mineral type, characteristics of pore fluid, microstructure of soil, and environmental conditions. Scanning electron microscope (SEM) can be used as a tool for a direct study of soil microstructure. In addition, one of the methods for evaluation of heavy metal contaminated clayey soils is related to the application of SEM. In this paper, a method for homogeneous sample preparation for SEM micrograph from clayey soil suspension is presented. Due to the importance of the application of undisturbed samples for SEM study, different methods of sample preparation including; peeling, fracturing, and resin application for contaminated soils are investigated. Sample of illite and kaolinite were laboratory contaminated with different concentrations of lead nitrate as a source of heavy metals. After achieving equilibrium, samples were exposed to the resin. Then, different sample preparation methods were applied for those contaminated illite and kaolinite. Finally, micrographs of samples were taken by scanning electron microscope. The impact of sample preparation method on the quality of SEM images in these clay minerals and in the presence of Pb ions is investigated. The prepared SEM pictures are compared with untreated samples as well. The results indicate that the exposure of samples to resin has a noticeable impact on the quality of SEM micrographs of contaminated clay minerals.