Characterization and Potential Use of Kombé Clay Materials in the Adsorption of Chromate and Nitrate Ions

Abstract

This work aims to evaluate the ability of Kombé clays, in the Republic of Congo, to adsorb chromate and nitrate ions in water. To do this, we first characterized the clay to obtain information on its physicochemical and mineralogical properties. We then performed chromate and nitrate ion adsorption tests on this material to assess its adsorption capacity. To characterize the Kombé clay, we used several analytical techniques, such as particle size distribution and Atterberg limits, X-ray diffraction (XRD), chemical analysis, cation exchange capacity (CEC), and specific surface area (SS). The results obtained show that the Kombé clay is plastic and composed of 52% clay, 18% silt, and 30% sand, with a predominance of kaolinite and a significant amount of quartz. Its CEC is 3 meq/100 g and its SS is 16 m²/g. Adsorption tests conducted on this clay indicate that it can be used for the adsorption of chromate and nitrate ions. The adsorption results show that Kombé clay removes 2.59% of chromate ions and 15.94% of nitrate ions. In light of these results, this study reveals that Kombé clay can be used in the treatment of polluted water as an adsorbent, as well as in applications for traditional and structural ceramics (bricks, tiles, etc.). However, this adsorption capacity is low and needs to be improved.