The aim of this study is to evaluate the applicability of the catalytic activity (CA) of the Fe₃O₄ magnetic system in the adsorption/degradation of methylene blue and esterification. The thermal decomposition method allowed the preparation of Fe₃O₄ nanoparticles. The crystallites of the Fe₃O₄ structural phase present an acicular form confirmed by X-ray diffraction. Transmission electron microscopy results identified the acicular shape and agglomeration of the nanoparticles. Mössbauer spectroscopy showed that the spectrum is composed of five components at room temperature, a hyperfine magnetic field distribution (HMFD), two sextets, a doublet, and a singlet. The presence of the HMFD means that a particle size distribution is present. Fluorescence spectroscopy studied the CA of the nanoparticles with methylene blue and found adsorption/degradation properties of the dye. The catalytic activity of the nanoparticles was evaluated in the esterification reaction by comparing the results in the presence and absence of catalyst for the reaction with isobutanol and octanol, where it is observed that the selectivity for the products MIBP and MNOP is favored in the first three hours of reaction.

The effect of the nitrogenation process on intrinsic magnetic properties such as saturation magnetization, anisotropy field, magnetocrystalline anisotropy constant, and Curie temperature of the (Nd1-xCex)1.1Fe10CoTi (x = 0.0, 0.5 and 1.0) alloys system are analyzed. The anisotropy field increases from 1.8 to 2.8 T with the substitution of Nd by Ce. The nitrogenation process resulted in an increase of the saturation magnetization, anisotropy field, and Curie temperature. The best magnetic properties were found for the Nd1.1Fe10CoTiNy compound, for which it was estimated a saturation magnetization of 153.3 Am2kg-1, anisotropy field of 10.3 T, anisotropy constant of 5.98 MJm-3, and Curie temperature of 768.9 K. A slight reduction in mean particle size was obtained after the nitrogenation process (~5.4 to ~3.9μm).