Amino acid-assisted synthesis of superparamagnetic CoFe2O4 nanostructures for the selective adsorption of organic dyes

We report a facile synthesis of superparamagnetic CoFe2O4 nanostructures with the assistance of an amino acid (lysine). Monodisperse CoFe2O4 nanospheres and nanoparticles were obtained by adjusting the synthesis parameters (such as the molar ratio of reactants and the solvent). The samples were characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. The magnetic property and measured zeta potential shows that both CoFe2O4 nanostructures were superparamagnetic and positively charged. The adsorption performance of the CoFe2O4 nanostructures was evaluated using different dyes, namely, methylene blue, Congo red, Acid Blue 80, methyl orange, rhodamine B, and Cationic red X-GTL, as models. The results show that CoFe2O4 nanospheres consisting of nanoparticles display high adsorption performance on methylene blue, methyl orange, and Congo red, whereas CoFe2O4 nanoparticles prefer adsorbing rhodamine B and Congo red. Therefore, the tunable synthesis of superparamagnetic CoFe2O4 nanostructures provides promising applications for the selective and highly efficient removal of various organic contaminants from industrial effluents.