Preparation of Fe₃O₄ Nanoparticles and Removal of Methylene Blue through Adsorption

In this work, we studied the catalytic activity, structural properties, and behavior of a Fe₃O₄ magnetic system. The Fe₃O₄ nanoparticles were prepared by the thermal decomposition method. X-ray diffraction confirmed the presence of a structural Fe₃O₄ phase, where acicular shape of the grains is shown. Transmission Mossbauer spectroscopy showed a wide distribution of particle sizes at room temperature, some of these present superparamagnetic behavior and are responsible of paramagnetic sites. The hysteresis loops obtained by the use of a vibrating sample magnetometer showed that these nanoparticles exhibit superparamagnetic behavior. However, the cycles present a significant contribution from a ferrimagnetic component at 2 K, which agrees with Mossbauer results. Through scanning electron microscopy, a tendency to the agglomeration of nanoparticles was observed. Nanoparticle activity in the degradation of methylene blue (MB) was studied through fluorescence spectroscopy, finding dye adsorption properties. (paper)