Magnetically recoverable Ni@C composites: The synthesis by carbonization and adsorption for Fe3+

Carbon-encapsulated nickel particles (Ni@C composites) for removing Fe³⁺ in wastewater have been prepared by the carbonization of phenolic resin mixing with nickel particles. XRD results reveal that the Ni@C composites are consisted of C, Ni, and Ni₃S₂. The TG-DTG curves of Ni@C composites are almost same as that of phenolic resin. The morphology investigation shows that Ni is distributed randomly on carbon. Based on analysis of N₂ adsorption-desorption isotherm, the surface area and pore volume of Ni@C composites are 187.47 m² g⁻¹ and 0.06900 cm³ g⁻¹ nm⁻¹, respectively. The saturation magnetization values for Ni@C composites are 68.99 emu·g⁻¹ determined by the Vibrating Sample Magnetometer. Ni@C composites exhibit a high adsorption capacity for Fe³⁺. The adsorption behavior follows the pseudo-second-order kinetic and Langmuir model between the adsorbents and Fe³⁺. Furthermore, the adsorption capacity of Ni@C composites derives from the attractive force between the adsorbed anion and the surface positive charge of Ni@C composites, as well as the bond between the adsorbed cation and the COO⁻ groups. From the above results Ni@C composites can be widely applied in wastewater treatment as a new efficiency and excellent recoverable adsorbent.