| Summary: | The magadiite–magnetite (MAG–Fe<sub>3</sub>O<sub>4</sub>) 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 Fe<sub>3</sub>O<sub>4</sub> and the high adsorption capacity of pure magadiite (MAG). MAG–Fe<sub>3</sub>O<sub>4</sub> 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 Fe<sub>3</sub>O<sub>4</sub> nanoparticles were deposited on the interlayer and surface of magadiite. MAG–Fe<sub>3</sub>O<sub>4</sub> was treated as an adsorbent for methylene blue (MB) removal from aqueous solutions. The adsorption properties of MAG–Fe<sub>3</sub>O<sub>4</sub> were investigated on methylene blue; however, the results showed that the adsorption performance of MAG–Fe<sub>3</sub>O<sub>4</sub> improved remarkably compared with MA and Fe<sub>3</sub>O<sub>4</sub>. The adsorption capacity of MAG–Fe<sub>3</sub>O<sub>4</sub> 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–Fe<sub>3</sub>O<sub>4</sub> was better than that of MAG and Fe<sub>3</sub>O<sub>4</sub>. Moreover, the adsorption behavior of MB on MAG–Fe<sub>3</sub>O<sub>4</sub> 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–Fe<sub>3</sub>O<sub>4</sub> nanocomposite was a monolayer adsorption.
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