Facile Synthesis of Fe<sub>3</sub>O<sub>4</sub> Nanoparticles Loaded on Activated Carbon Developed from Lotus Seed Pods for Removal of Ni(II) Ions

Abstract

In this study, a simple one-step synthetic approach using lotus seed pods and iron(III) chloride has been developed to prepare Fe3O4 nanoparticles loaded activated carbon composite (Fe3O4-NPs/AC) for removal of Ni(II) ions from aqueous solution. The physical and chemical characteristics of Fe3O4-NPs/AC were comprehensively analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and Brunauer–Emmett–Teller analysis. On account of the combined advantages of lotus seed pod carbon and Fe3O4 nanoparticles, the Fe3O4-NPs/AC showed excellent adsorption efficiency for Ni(II) ions with the maximum adsorption capacity of 50.72 mg g-1 at optimal conditions (pH of 6, contact time of 60 min, 25 °C, and adsorbent dosage of 4.0 g L-1). It was found that the adsorption process of Ni(II) on Fe3O4-NPs/AC was feasible, spontaneous and endothermic, and was well described by the Langmuir isotherm model and pseudo-first-order kinetic equation. The Fe3O4-NPs/AC composite also showed good reusability with removal efficiency of greater than 86.25% after five cycles of reuse.