Synthesis and adsorption properties of hierarchical Fe3O4@MgAl-LDH magnetic microspheres

In this study, Fe3O4 microspheres were prepared by a hydrothermal method, and then the synthesized Fe3O4 microspheres were used as template to prepare Fe3O4@MgAl-LDH composite microspheres by a coprecipitation process. Morphology, composition, and crystal structure of synthesized nanomaterials were characterized by X-ray powder diffractometry, scanning electron microscopy, and Fourier transform infrared spectroscopy technologies. The composite hierarchical microspheres are composed of inner Fe3O4 core and outer MgAl-LDH-nanoflake layer, and the average thickness of MgAl-LDH-nanoflake is about 70 nm. The adsorption property of the products toward congo red was also measured using UV–vis spectrometer. The result demonstrated that the Fe3O4@MgAl-LDH composite adsorbent could remove 99.8% congo red in 30 min, and the maximum adsorption capacity is about 404.6 mg/g, while congo red removal rate of pure MgAl-LDH and Fe3O4 are only 86.3 and 53.1% in 40 min, respectively, and their adsorption capacity are 345.72 and 220.56 mg/g, respectively. It indicates the composite Fe3O4@ MgAl-LDH nanomaterials have better adsorption performance than pure Fe3O4 and MgAl-LDH nanomaterials. In addition, the magnetic nanocomposites could be separated easily, and it demonstrated good cycle performance.