Characterisation of Clay Minerals from Ebonyi State and Their Potential Application in Wastewater Treatment

Natural clay minerals are increasingly recognised as low-cost, abundant adsorbent materials with promising applications in wastewater treatment, particularly in resource-limited settings. This study characterises clay minerals collected from three geological formations in Ebonyi State, South East Nigeria, and evaluates their adsorption capacity for the removal of methylene blue dye and ammonium ions from synthetic wastewater. Clay samples were characterised by X-ray fluorescence spectroscopy, X-ray diffraction, differential thermal analysis, and scanning electron microscopy to determine chemical composition, mineralogy, thermal behaviour, and morphology. Batch adsorption experiments were conducted under varying conditions of pH, contact time, adsorbent dose, and initial contaminant concentration. Equilibrium data were analysed using Langmuir and Freundlich adsorption isotherm models, and kinetic data were fitted to pseudo-first-order and pseudo-second-order models. Results indicate that the clay samples are predominantly kaolinite with minor illite and smectite components. Maximum adsorption capacities calculated from the Langmuir model reached 45.2 milligrams per gram for methylene blue and 28.4 milligrams per gram for ammonium. Adsorption kinetics followed the pseudo-second-order model for both pollutants. The study demonstrates that Ebonyi State clay minerals possess significant adsorption potential and recommends further investigation of acid-activated and heat-treated modifications to enhance their performance for practical wastewater treatment applications. Keywords: clay minerals, adsorption, wastewater treatment, Ebonyi State, methylene blue