Study of the preparation of γ-Al2O3 nano-structured hierarchical hollow microspheres with a simple hydrothermal synthesis using methylene blue as structure directing agent and their adsorption enhancement for the dye

•The γ-Al2O3 were prepared using methylene blue as structure directing agent.•The microstructure of the prepared adsorbents can be effectively controlled.•The mechanism of the enhanced adsorption can be explained by template synthesis.

The γ-Al2O3 nano-structured hierarchical hollow microspheres were prepared with a simple hydrothermal synthesis using methylene blue as structure directing agent and the structure directing agent was removed after the γ-Al2O3 samples were calcinated at 600 °C for 2 h. The microstructural and properties of the prepared γ-Al2O3 samples were characterized by X-ray diffraction (XRD), TEM, BET, FT-IR. The static adsorption of γ-Al2O3 for methylene blue was conducted. The results showed that when 20 mg (the molar ratio of Al3+ to structure directing agent was 56:1) of structure directing agent was used, the γ-Al2O3 samples were prepared with that the specific surface area increased by 31% and the maximum adsorption capacity for methylene blue was 8.38 mg/g, increased by 61%.In addition, the adsorption equilibrium isotherms model and adsorption kinetics model were investigated. The adsorption of γ-Al2O3 for methylene blue is best fitted with Langmuir adsorption model, the kinetic process of adsorption can be described by the pseudo-second-order kinetic model.This study demonstrates the microstructure of γ-Al2O3 can be effectively controlled and the adsorption properties of it is improved using template synthesis with a proper amount of methylene blue as structure directing agent.