The Efficient Adsorption Removal of Cu(II) by Using Fe₃O₄/TiO₂/Graphene Ternary Nanocomposites

A novel magnetic Fe₃O₄/TiO₂/Graphene (FTG) ternary composite, which possessed highly specific surface area, surface activities and adsorptive performance, was synthesized and used as adsorbent for Cu(II) adsorption removal from in aqueous solution. The crystal structure, morphology and special surface area of FTG nanocomposite were characterized by X-ray diffraction, scanning electron microscopy, and N₂ adsorption-desorption isotherm. The surface morphology and properties of FTG were modified significantly. The specific surface area of FTG was 422.84 m² · g^-1, which led to the excellent adsorption capacity for Cu(II) (87.4 mg · g^-1). The adsorption kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm model could well fit the adsorption data. There were three steps in the adsorption process, such as the instantaneous adsorption step, the intraparticle diffusion and the final equilibrium stage. The reaction rate decreased along with temperature increasing, which indicated the adsorption for Cu(II) was an exothermic process. The E_a was 17.32 kJ · mol^-1 for FTG, which illustrated the adsorption of Cu(II) onto the surface of ternary nanocomposite was a physical process. After recycling five times, the decline of adsorption capacity of FTG for Cu(II) was 7.4%, which indicated that the adsorbents could be recycled in the removal of Cu(II). It was proved that FTG nanocomposite might be used as excellent adsorbent to remove heavy metal ions in wastewater.