Characterization and adsorption properties of La and Fe modified activated carbon for dye wastewater treatment

An effective adsorbent (Fe-La-AC) was synthesized by impregnating mixed solution ferric nitrate and lanthanum nitrate with activated carbon and heated by microwave to remove methylene blue (MB) from dye wastewater. The Fe-La-AC was characterized by N-2 adsorption, Fourier transform infrared spectroscopy, Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and scanning electron microscopy. Moreover, the existence of Fe3O4 leads to Fe-La-AC having magnetic properties, which makes it easily separated and recycled from dye wastewater in an external magnetic field. After modification, the following phenomena occurred: Brunauer-Emmett-Teller surface area, average pore diameter, and total pore volume decreased; graphitization degree decreased. In addition, the equilibrium isotherms and kinetics of MB adsorption on raw activated carbon and Fe-La-AC were examined. The equilibrium adsorption data indicated that the adsorption behavior followed the Langmuir isotherm, and the pseudo-second-order model matched well the kinetic data. The maximum adsorption capacity of Fe-La-AC is 261.10 mg/g, which increases by 26.38% as compared with raw activated carbon. According to these results, Fe-La-AC is a promising adsorbent for the removal of MB from dye wastewater.