Characterising the physicochemical properties of selected geophagic clay from the Democratic Republic of Congo (DRC) to investigate their potential applications

Clay and clay composite have been used for numerous applications around the world including as construction materials, cosmetics, and absorbents. As easy to find, abundant, and sustainable, the knowledge of the quality of clay is crucial. This study focuses on the characterization of geophagic clay samples from various locations in the Democratic Republic of Congo (DRC) to investigate their potential use in various sectors. The geophagic clays have different colors, different morphology, and properties. Many characterizations were carried out including X-ray diffraction, X-ray fluorescence spectroscopy, and fourier transform infrared (FTIR). The microstructure and chemical analysis were carried out using scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS). UV-Vis spectroscopy was also carried out to investigate the reflectance. XRD revealed the presence of Muscovite, Kaolinite, Illite, Muscovite, and Quartz. On the other hand, XRF showed the presence of SiO₂, Al₂O₃, TiO₂, and Fe₂O₃ as major chemical compounds. A flake-like surface morphology was observed in all the samples and the EDS analyses exhibited similar results as the XRF. The XRF, XRD, and EDS results were in agreement. The Zeta potential was negative for all the clay samples. The properties exhibited by the selected geophagic clay were compared with the properties of various samples used for different applications. It was concluded that the selected geophagic clays demonstrated properties that could lead to their use for water treatment and other applications including the cosmetic industry.