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 degrees 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 R-2 = 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.