Structural analysis and catalytic activity of Fe₃O₄ nanoparticles prepared by a facile co-precipitation method in a rotating packed bed

Fe₃O₄ nanoparticles were prepared via a facile co-precipitation method in a rotating packed bed (RPB) in a continuous mode. Exactly how the rotating speed, flow rates of the reactants and precipitant, and concentrations of the reactants and precipitant affect the size of Fe ₃O₄ nanoparticles was also investigated. Experimental results indicate that a higher rotating speed and larger flow rates of the reactants and precipitant were associated with a smaller size of Fe ₃O₄ nanoparticles. However, concentrations of the reactants and precipitant only slightly affected the size of Fe ₃O₄ nanoparticles. Additionally, the structural characterization of as-prepared Fe₃O₄ nanoparticles with an average size of 5.1 nm was studied using SEM, TEM, FTIR, XPS, and SQUID. Importantly, Fe₃O₄ nanoparticles displayed superparamagnetic behavior at 25 °C with saturation magnetization of 50 emu/g. Moreover, the catalytic activity of Fe₃O₄ nanoparticles was evaluated by the degradation of dyes (Rhodamine B: RhB, and Methylene blue: MB) in the presence of H₂O₂. According to those results, Fe₃O₄ nanoparticles could activate H ₂O₂ and, thus, had a degradation efficiency of 98% and 80% for RhB and MB, respectively, in 120 min.