Synthesis of magnetic iron‐manganese oxide coated graphene oxide and its application for adsorptive removal of basic dyes from aqueous solution: Isotherm, kinetics, and thermodynamic studies

Abstract

Adsorptive removal of cationic dyes such as methyl violet (MV) and methyl green (MG) from aqueous solution using magnetic iron‐manganese oxide coated graphene oxide (IMGO) was examined. The IMGO was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction (XRD), N2 adsorption–desorption isotherm, and vibrating sample magnetometer. The effect of different process parameters such as contact time, IMGO dose, initial dyes concentration, initial solutions pH, and temperature was investigated. The equilibrium experimental data were fitted with Langmuir, Freundlich, Dubinin–Radushkevich (D‐R), and Temkin isotherm models. The data fitted well with Freundlich isotherm model suggesting multilayer adsorption of dyes onto heterogeneous adsorbent surface. The Langmuir adsorption capacity (Qm, mg/g) of IMGO with MV and MG was 172.96 and 195.64, respectively. The data obeyed the pseudo‐second order kinetic model, and the mechanism of adsorption was controlled by both intra‐particle and liquid film diffusion models. The adsorption process was found to be spontaneous, endothermic, and physical in nature. The dye‐loaded IMGO was regenerated and used for at least four cycles without any substantial loss of its efficacy. The present adsorptive removal studies of MV and MG revealed that IMGO is an effective and efficient adsorbent for the removal of basic dyes from aquatic system. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S214–S229, 2019