Superior adsorption of methyl blue on magnetic <scp>Ni–Mg–Co</scp> ferrites: Adsorption electrochemical properties and adsorption characteristics

Abstract

Abstract The harm and treatment of methyl blue (MB) were described, and the necessity for the removal of MB by magnetic nanomaterials was explained. Magnetic Ni–Mg–Co ferrites were prepared by the rapid combustion approach of an active nitrate solution and characterized by X‐ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), energy dispersive spectroscopy, and vibrating sample magnetometer. Magnetic Ni 0.1 Mg 0.7 Co 0.2 Fe 2 O 4 nanoparticles prepared at 400°C with the saturation magnetization of 19.7 emu g −1 and the average diameter of about 15.2 nm were used to adsorb MB from the aqueous medium. The Brunauer‐Emmett‐Teller (BET) analysis showed that the specific surface area was 143.17 m 2 g −1 and the average pore size was 9.44 nm. The adsorption mechanism of MB onto magnetic Ni 0.1 Mg 0.7 Co 0.2 Fe 2 O 4 nanoparticles was studied, and the results revealed that the adsorption properties conformed the pseudo‐second‐order kinetics model due to the square deviation values ( R 2 &gt; 0.98), and Temkin model could describe the adsorption state of MB onto Ni 0.1 Mg 0.7 Co 0.2 Fe 2 O 4 nanoparticles, which suggested that the adsorption of MB onto Ni 0.1 Mg 0.7 Co 0.2 Fe 2 O 4 nanoparticles was monolayer–multilayer hybrid chemisorption mechanism. When the pH value exceeded 3, the adsorbance reached large value; while, the adsorbance was 97.6% of the initial adsorption value for seven cycles. The electrochemical impedance spectroscopy and cyclic voltammetry curves of MB adsorbed onto the nanoparticles before and after the adsorption were determined.