Characterising the Physicochemical Properties of Selected Geophagic Clay from the Democratic Republic of Congo (DRC) to Investigate Their Potential Applications

Abstract

Clay and clay composites have been used for numerous applications around the world, for example, as construction materials, cosmetics, and absorbents. Since clay is easy to find, abundant, and sustainable, understanding its quality 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 uses in various sectors. Geophagic clays have different colors, morphologies, and properties. Many characterizations were carried out including X-ray diffraction and X-ray fluorescence spectroscopy. Microstructure and chemical analyses were carried out using scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS). UV–Vis spectroscopy was also carried out to investigate reflectance. XRD revealed the presence of muscovite, kaolinite, illite, 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 samples and the EDS analyses exhibited similar results to 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 in water and wastewater treatments and other applications, including as a sunblock (cosmetic industry) due to their mineralogical/chemical composition and UV–Vis reflectance.

Keywords

• clay
• geophagia
• chemical properties
• mineralogy
• zeta potential