Comparative Analytical Performance of Magnetic ZnO-Modified Activated Carbons Derived from Ziziphus spina-christi and Cordia myxa Seeds for the Removal of Cd(II) and Ni(II) Ions from Aqueous Solutions

Growing discharge of harmful heavy metals into aquatic ecosystems has prompted an ever-expanding effort to discover effective, viable, and low-cost adsorbents for water treatment. Using the hydrothermal synthesis method, this study successfully prepared and modified activated carbons from Ziziphus spina-christi (ZAC) and Cordia myxa (CAC) seeds with magnetic zinc oxide nanoparticles (MZnO). Various mass ratios of activated carbon to MZnO were mixed to prepare composite adsorbents, where the ۲:۱ ratio showed the optimum adsorption capacity and was selected for further studies. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), and zeta potential analysis were used to characterize the synthesized materials in detail. The characterization results confirmed that the magnetic ZnO nanoparticles can be successfully embedded into a porous activated carbon matrix while maintaining the functional groups responsible for metal ion adsorption. This study presents batch adsorption experiments to assess the removal of Cd(II) and Ni(II) ions at various operating conditions (initial metal ion concentration, contact time, solution pH). The maximum adsorption conditions were also realized at initial metal ion concentrations of ۵۰ mg L⁻¹, contact time of ۶۰ min for Cd and ۱۲۰ for Ni for CAC/MZnO. The contact time was ۱۵۰ min for Cd and ۱۸۰ for Ni for ZAC/MZnO. and pH ۶. The improved adsorption performance may be attributed to the combined contribution of the porous activated carbon framework and the active sites provided by the magnetic ZnO nanoparticles. The developed composites showed good adsorption capacity for both Cd(II) and Ni(II), indicating that they can be applied as an effective medium of environmentally friendly, easy-to-reprocess, efficient, and cheap adsorbents for treating heavy metal-polluted water.The adsorption equilibrium of Cd(II) and Ni(II) was better fitted by the Langmuir isotherm than the Freundlich model. The highest adsorption capacity was achieved by ZAC/MZnO (۲:۱) for Cd(II) (qmax = ۱۴۲.۸۶ mg g⁻¹), followed by ZAC/MZnO for Ni(II) (۱۱۶.۹۰ mg g⁻¹), CAC/MZnO for Cd(II) (۱۰۳.۶۳ mg g⁻¹), and CAC/MZnO for Ni(II) (۸۸.۵۴ mg g⁻¹), confirming the superior adsorption efficiency of ZAC/MZnO.

کلیدواژه ها:

Activated Carbon ، Ziziphus spina-christi ، Cordia Myxa ، Magnetic ZnO ، Cd(II) ، Ni(II) ، Adsorption ، Water treatment