Solvothermal synthesis of magnetic FexOy/C nanocomposites used as adsorbents for the removal of methylene blue from wastewater

Magnetic iron oxides/carbon nanocomposites have been synthesized by a facile, one-step solvothermal method. XRD analysis evidenced the presence of a spinel phase in all samples, while FT-IR analysis suggested the presence of magnetite in the prepared samples. Mossbauer spectra, registered after 2 month, evidenced the complete transition of magnetite into maghemite. SEM images showed homogenous spherical nanoparticles with diameters up to 20 nm, smaller in case of the sample without carbon. The magnetic measurements showed that the saturation magnetization (Ms) value decreases with the increase in carbon content in composites. The values of Ms were higher than 30 emu g(-1), allowing the magnetic separation of the adsorbents. The FexOy/C and FexOy/2C nanocomposites were tested as adsorbents for methylene blue; the removal efficiency has increased with the carbon content of the adsorbents. The kinetic studies revealed that the adsorption process followed the pseudo-second-order model and the equilibrium data were correlated by the Redlich-Peterson isotherm.