Browsing by Author "Naouel , Hezil"

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    Improving the effectiveness of clay minerals for the removal of heavy metals
    (2025) Naouel , Hezil
    The 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.g 1 , respectively.
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    Synthesis, structural, electrochemical and tribological characterization of nanostructured compound based on titanium (Ti-Ni) for biomedical applications
    (2025) Naouel , Hezil
    ABSTRACT Medical implants are essential for improving the quality of life of people who suffer, especially in the orthopedic field. Therefore, the need for biomaterials has increased exponentially as a result of the necessity for replacing or repairing damaged parts of the human body to regain the missing shape or functionality of biological tissue. To achieve the long-term performance of these implants, they must have distinct mechanical, tribological, and electrochemical properties. In this context, this study aims to examine the effect of milling times on the mechanical, tribological, and electrochemical properties of Ti 50 -Ni 50 (or Nitinol), which is one of the most attractive materials in the medical field for orthopedic implants due to its unique properties. Ti 50 -Ni 50 alloys were synthesized using high-energy ball milling under different milling times (2, 6, 12, and 18 h). The size, shape, and uniform chemical composition of the powder particles were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The alloyed particles' structural characteristics were determined through the use of X-ray diffraction (XRD). Mechanical properties were assessed using hardness tests, while tribological behavior was examined using a ball-on-plate tribometer operating in Ringer's Solution under various applied load of 2, 10, and 20 N. The electrochemical properties were characterized by open-circuit potential (OCP) measurement, potentiodynamic polarization (PD), and the Electrochemical Impedance Spectroscopy (EIS) technique. To simulate typical biological conditions, Hank's solution at pH = 7.4 and T = 37 °C were used as the electrolyte. The results revealed that the milling process influences the particle size and shape of powders, where the proportion of fine particles increased with increasing grinding times from 2 h to 18 h due to severe deformation and fracturing. This improvement in particle refinement contributed to enhanced mechanical attributes, wear resistance, and corrosion resistance, making the material useful for bone implants.