Preparation and Characterization of Magadiite⁻Magnetite Nanocomposite with Its Sorption Performance Analyses on Removal of Methylene Blue from Aqueous Solutions.

The magadiite⁻magnetite (MAG⁻Fe₃O₄) nanocomposite has great potential applications in the field of biomaterials research. It has been used as a novel magnetic sorbent, prepared by co-precipitation method. It has the dual advantage of having the magnetism of Fe₃O₄ and the high adsorption capacity of pure magadiite (MAG). MAG⁻Fe₃O₄ was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The results showed that Fe₃O₄ nanoparticles were deposited on the interlayer and surface of magadiite. MAG⁻Fe₃O₄ was treated as an adsorbent for methylene blue (MB) removal from aqueous solutions. The adsorption properties of MAG⁻Fe₃O₄ were investigated on methylene blue; however, the results showed that the adsorption performance of MAG⁻Fe₃O₄ improved remarkably compared with MA and Fe₃O₄. The adsorption capacity of MAG⁻Fe₃O₄ and the removal ratio of methylene blue were 93.7 mg/g and 96.2%, respectively (at 25 °C for 60 min, pH = 7, methylene blue solution of 100 mg/L, and the adsorbent dosage 1 g/L). In this research, the adsorption experimental data were fitted and well described using a pseudo-second-order kinetic model and a Langmuir adsorption isotherm model. The research results further showed that the adsorption performance of MAG⁻Fe₃O₄ was better than that of MAG and Fe₃O₄. Moreover, the adsorption behavior of MB on MAG⁻Fe₃O₄ was investigated to fit well in the pseudo-second-order kinetic model with the adsorption kinetics. The authors also concluded that the isothermal adsorption was followed by the Langmuir adsorption isotherm model; however, it was found that the adsorption of the MAG⁻Fe₃O₄ nanocomposite was a monolayer adsorption.