Economical magnetic activated carbon for methylene blue removal from water

This study investigates an easy synthesis method of magnetic activated carbon (Fe3O4/AC) composites by ultrasonic mechanical blending of Fe3O4 particles and activated carbon (AC) powder at different mass ratios. The materials with the best performance were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), specific surface and porosity analyzer (BET), hysteresis loop meter (VSM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS). The as-prepared Fe3O4/AC was used to remove the contaminant methylene blue (MB) from solution. The effects of initial solution pH, material dosage, and temperature on MB removal were studied. A series of batch experiments demonstrated that the Fe3O4/AC with a mass ratio of Fe3O4 to AC = 1:5 showed a higher adsorption capacity of 251.3 ± 2.0 mg/g at 20 °C and pH = 6.5. Isotherm and kinetic studies indicated that the MB adsorption onto Fe3O4/AC was exothermic in a chemical monolayer adsorption process. The purification mechanism of Fe3O4/AC was investigated, FT-IR results showed that MB molecules adhered to Fe3O4/AC after purification. From the results of XPS full spectrum and high resolution spectrum, the possible purification mechanism is inferred as follows: electronic transfer between =N+ in MB and Cdouble bondO/C─O in Fe3O4/AC, as well as π-π interaction between the skeleton sheet of Fe3O4/AC and aromatic ring of MB. This study provides the theoretical reference and experimental basis for recovery and utilization of easily-obtained Fe3O4/AC to remove MB from wastewater.