Abstract
Clay minerals are commonly used as adsorbents due to their wide availability, large specific surface area, and cation exchange capabilities, making them suitable for removing heavy metal ions from wastewater. This study investigated the activation of clay by acid and thermal treatment to obtain an adsorbent for the purification of uranium from impurities such as iron and magnesium. Acid modification of clay samples was carried out with sulfuric acid (15%) at a temperature of 80–90 °C for 3 hours. While the activation of the clay using the thermal process was performed at 600–650 °C for 12–24 hours. X-Ray Diffraction, Electron Paramagnetic Resonance (EPR), and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyse the clay's chemical composition and structural changes before and after activation. FTIR identified free OH groups and hydrated SiO2. EPR showed a high level of paramagnetic centers linked to structural defects and oxygen vacancies, which contribute to the material's strong adsorption and catalytic activity. After acid treatment, the clay particles exhibited a notable rise in specific surface area, expanding from 35.2 m²/g to 342.5 m²/g. Additionally, the specific pore volume grew substantially, increasing from 0.024 cm³/g to 0.30 cm³/g.