Rectorite–TiO2–Fe3O4 composites: Assembly, characterization, adsorption and photodegradation

Rectorite–TiO2–Fe3O4 (RTF) composites were assembled by orderly depositing anatase TiO2 and magnetic Fe3O4 nanoparticles on rectorite (REC) surfaces. Rectorite–TiO2 (RT) and RTF composites were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). TiO2 particles partially exfoliated the REC layers, while Fe3O4 particles completely exfoliated the REC sheets. Fe3O4 particles was absorbed by REC and consequently appeared on its surface instead of being on the TiO2 particles. RTF can be easily separated from aqueous solution by magnet. The adsorption and photodegradation of methylene blue (MB) by RT and RTF were also investigated. The kinetic adsorption fit the pseudo-second-order model and the isotherm data followed the Langmuir model. The maximum adsorption capacities for MB were 187.61 and 169.20 mg/g for RT and RTF, respectively. RTF exhibited a good capability for removal of MB from aqueous solution, and about 95% MB was removed after 12 h UV-light irradiation, and about 75% MB removal for RT. And RTF exhibited the similar photocatalytic activity with RT for the persistent organic pollutant 4-nitrophenol (4-NP) under UV irradiation.