Abstract
This study investigates the dynamic removal of lead(II) ions using biosorbents derived from peach shells and raw eggshells, forming composite chitosan adsorbents. Biosorbents were produced from peach shell (PS), carbonized peach shell (PSC), and acidified carbonized peach shell (APSC), then impregnated onto chitosan to form composites (PSCh, PSCCh, and APSCCh). Adsorption kinetics and thermodynamics were studied at temperatures of 25, 35, and 45 ± 1 °C. FTIR, XRD, SEM, and EDX analyses revealed morphological changes after bioadsorption. Four isotherm and kinetic models evaluated the adsorption efficiency. The pseudo-second-order kinetic model showed the best fit, with R2 values up to 0.999. Langmuir isotherm analysis indicated single-layer adsorption, with maximum capacities reaching 50 mg/g. Thermodynamic parameters confirmed the process as spontaneous, endothermic, and chemisorption-driven, with ΔG0 values ranging from −24.02 to −28.21 kJ/mol and activation energies (Ea) of 8.91–24.51 kJ/mol. Changes in enthalpy (ΔH0: 6.43–22.03 kJ/mol) and entropy (ΔS0: 0.109–0.156 kJ/mol.K) indicated increased surface randomness. Overall, the study highlights the efficiency of chitosan-impregnated peach shell biosorbents for lead removal, offering a promising, eco-friendly solution for water treatment applications.
