Adsorption Characteristics of Reactive Blue onto Magnetic NiCoFe₂O₄ Nanoparticles Prepared via Alcohol-Solution Combustion Process.

Magnetic NiCoFe₂O₄ nanoparticles were prepared via the alcohol-solution combustion process, the morphology and magnetic property of them were investigated by the scanning electron microscopy (SEM), the transmission electron microscope (TEM), the X-ray diffraction (XRD), the vibrating sample magnetometer (VSM), the energy dispersive spectroscopy (EDS) and the Brunauer-Emmett-Teller (BET). The as-prepared magnetic NiCoFe₂O₄ nanoparticles calcined at 400 °C for 2 h with absolute alcohol of 30 mL were characterized with the average nanoparticle size of around 30 nm and the specific magnetization (Ms) of 14.7 emu/g. The adsorption characteristics of reactive blue (RB) from aqueous solutions onto NiCoFe₂O₄ nanoparticles were investigated by UV spectroscopy at room temperature; the adsorption kinetics data were in good agreement with the pseudo-second-order kinetic model in the initial RB concentrations of 100-400 mg/L. Compared with Langmuir and Freundlich models, the Temkin model (correlation coefficient ² =0.9998) could be used to evaluate the adsorption isotherm of RB onto the magnetic NiCoFe₂O₄ nanoparticles at room temperature, which revealed that the adsorption of RB onto the magnetic NiCoFe₂O₄ nanoparticles was a hybrid of monolayer and multilayer adsorbing mechanism.