Adsorption Performance of Congo Red onto Magnetic Ni0.4Co0.2Zn0.4Fe2O4 Nanoparticles Prepared via the Rapid Combustion Process

: Magnetic Ni0.4Co0.2Zn0.4Fe₂O₄ nanoparticles were prepared via the rapid combustion process, the morphology and magnetic property of them were investigated by SEM, TEM, XRD, VSM, and FTIR. The as-prepared magnetic Ni0.4Co0.2Zn0.4Fe₂O₄ nanoparticles calcined at 400 °C for 2 h with absolute alcohol of 20 mL were characterized with the average nanoparticle size of around 25 nm and the specific magnetization of 35.2 emu/g. The adsorption kinetics and adsorption isotherms of Congo red (CR) from aqueous solutions onto Ni0.4Co0.2Zn0.4Fe₂O₄ 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 CR concentrations of 200-500 mg/L. By comparison of Langmuir, Freundlich and Temkin models for adsorption isotherms of CR, the Temkin model (correlation coefficient R₂ = 0.9969) could be used to evaluate the adsorption isotherm of CR onto the magnetic Ni0.4Co0.2Zn0.4Fe₂O₄ nanoparticles at room temperature, which suggested that the adsorption of CR onto the magnetic Ni0.4Co0.2Zn0.4Fe₂O₄ nanoparticles was a hybrid of monolayer and multilayer absorbing mechanism.