Solvothermal synthesis of magnetic CoFe2O4/rGO nanocomposites for highly efficient dye removal in wastewater

Abstract

Magnetic CoFe₂O₄/reduced graphene oxide (rGO) (abbreviated as CFG) nanocomposites were fabricated by a simple solvothermal process. The structure and composition of the as-synthesized CFG nanocomposites were investigated by transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), N₂ adsorption–desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. TEM images show that the uniform CoFe₂O₄ NPs (∼11 nm) are well dispersed on the rGO nanosheets. In addition, CFG has a high surface area (239.76 m² g⁻¹), exhibits a strong magnetic strength (59.20 emu g⁻¹), and can be easily separated from other constituents under an external magnetic field. When using organic dyes, such as rhodamine B (Rh B), methylene blue (MB), Congo red (CR), methyl orange (MO), and methyl green (MG), as the adsorbates, CFG showed a good adsorption performance, especially, ∼100% for MB within 5 min. The maximum adsorption capacities for Rh B, MB, CR, and MG were 121.8, 93.5, 104.5, and 88.3 mg g⁻¹, respectively. The effect of certain variables, such as temperature, pH of the initial solution, adsorbent dose, and adsorbate species, was studied in detail. All results suggested that CFG can be used as an environmentally friendly and highly efficient reusable adsorbent material with a high adsorption capacity and a fast removal rate that can be used to remove organic dyes from wastewater.