Rim Imen2025-08-312025-08-312025http://dspace.univ-khenchela.dz:4000/handle/123456789/9348The discharge of heavy metals into the environment represents a significant threat to ecosystems and human health. Among the available strategies, adsorption is widely considered to be the most promising due to its clarity, affordability, and high efficiency in eliminating metal ions, even in small amounts. The objective of this thesis is to enhance the adsorbent capacity of kaolin-type (from Guelma, east of Algeria) clays through chemical means, with the subsequent intention of utilizing these materials to remove heavy metals from an aqueous phase. The initial modification entailed the use of diphenylamine to synthesize DPA-Kaolin, with the objective of efficiently removing lead (II) and copper (II) from aqueous solutions. The subsequent modification involved the modification of kaolin with surfactants (SLS, SDBS, and their mixture), with the aim of efficiently removing mercury (II) from aqueous solutions. The characterization of the samples was conducted through a range of analytical methodologies, encompassing X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) to ascertain their structural composition. In addition, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) analysis were employed to determine their morphological characteristics. The findings showed an increase in the BET specific surface area of kaolin by nearly 25% (from 66.69 m².g−1 to 71.35 m².g−1) after DPA modification, and this increase demonstrated significantly greater maximum adsorption capacities for Pb(II) and Cu(II) on DPA-kaolin than on Nat-kaolin, with values of 151 μmol.g-1 and 134 μmol.g-1, respectively, suggesting an enhanced adsorption capacity, which confirmed the successful modification of kaolin using DPA. Conversely, the specific surface area of kaolin increased significantly with the addition of surfactants, reaching 38.3%, 31.9%, and 17.5% for K-SLS, K-SDBS, and K-M, respectively. This finding indicates that the mercury adsorption capacity of kaolin modified with anionic surfactant SLS surpasses that of kaolin modified with a mixture of surfactants (SLS+SDBS) and finally kaolin modified with anionic surfactant SDBS. The corresponding values for mercury adsorption capacity were determined to be 17.77mg.g-1, 15.77mg.g-1, and 13.45 mg.g1, respectively.enThesis