Magnetic nanocomposite adsorbents are cost-effective, environmentally friendly, easy to use, and highly efficient at removing metals from large volumes of wastewater in a short time by using an external magnetic field. In this study, an Fe₃O₄/NiO composite nanoadsorbent was prepared by varying the mass percent ratios of NiO (50, 40, 30, 20%), which are denoted Fe₃O₄/50%NiO, Fe₃O₄/40%NiO, Fe₃O₄/30%NiO, and Fe₃O₄/20%NiO, respectively, using Hagenia abyssinica plant extract as the template/capping agent and a simple mechanical grinding technique. The nanocomposites were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption, and ζ-potential measurements. The adsorption performance of the nanoadsorbent was assessed for the removal of lead (Pb²⁺) ions from aqueous solutions. Among the composite adsorbents, Fe₃O₄/50%NiO demonstrated the best Pb(II) removal efficiency (96.65%) from aqueous solutions within 80 min at pH 8, at a 100 mg/L lead concentration and 0.09 g of adsorbent dose. However, with the same parameter, only 62.8% of Pb(II) was removed using Fe₃O₄ nanoparticles (NPs). The adsorptive performance indicated that the optimum amount of porous material (NiO) in the preparation of the Fe₃O₄/NiO composite nanoadsorbent, with the aid of H. abyssinica plant extract, enhances the removal of toxic heavy metals from aqueous solutions. Multiple isotherm and kinetic models were used to analyze the equilibrium data. Adsorption isotherm and kinetic studies were found to follow the Freundlich isotherm and pseudo-second-order kinetics, respectively.

Abdurohman Eshetu Ferenj

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