One-pot synthesis of biomorphic Mg-Al mixed metal oxides with enhanced methyl orange adsorption properties

• One-pot method was used for preparing biomorphic Mg-Al mixed metal oxides.
• Hierarchically biomorphic Mg-Al mixed metal oxides successfully replicated the structure of cotton fiber.
• The adsorption capacity of biomorphic Mg-Al mixed metal oxides was higher than that of Mg-Al mixed metal oxides.

Biomorphic Mg-Al mixed metal oxides with hierarchical structures were synthesized by a one-pot method employing cotton fibers as templates. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the as-prepared biomorphic Mg-Al mixed metal oxides retained the tubular morphology of cotton fibers. Adsorption of biomorphic Mg-Al mixed metal oxides for methyl orange was investigated in detail. Different conditions were evaluated, including adsorbent dosage, initial methyl orange concentration, adsorption time and temperature. The adsorption mechanism was also discussed according to the adsorption kinetics and thermodynamics. The results indicated that the adsorption process was well fit to Freundlich isotherm model and pseudo-second-order kinetic model.