The preparation of novel adsorbent materials with efficient adsorption performance for both chromium and methylene blue

The hydroxy-functionalized ionic liquids (ILs) modified with magnetic chitosan/grapheneoxide (MG-ILs-OH) were synthesized. The surface morphology of MG-ILs-OH was characterized by transmission electron microscopy, X-ray diffraction, thermo gravimetric analysis and Fourier transform infrared spectroscopy techniques. It was found that the adsorption kinetics is well fitted by a pseudo-second-order model and the adsorption isotherms agree well with the Langmuir model, and the MG-ILs-OH could be repeatedly used by simple treatment. The results showed that the addition of ILs-OH can largely increase the adsorption sites (hydroxy and amino groups) and adsorption properties. The MG-ILs-OH were used as adsorbent for the removal of methylene blue (MB) and Cr(VI) from simulated wastewater with a fast solid–liquid separation in the presence of external magnetic field. The maximum obtained adsorption capacities of MB and Cr(VI) were 243.31 and 107.99   mg/g, respectively. The application of MG-ILs-OH could effectively solve the problem that the adsorbent only adsorb similar adsorbate.