Self‐Assembled 3D Hierarchically Structured Gamma Alumina by Hydrothermal Method

Abstract

Self‐assembled γ‐Al2O3 with hierarchical structure was successfully obtained via thermolysis of γ‐boehmite (γ‐AlOOH) particles, which was hydrothermally derived from aluminum ammonium sulfate hydrate (NH4Al(SO4)2·12H2O), urea, poly‐glycol (PEG)‐2000, and deionized water. SEM observations indicate that the as‐synthesized γ‐AlOOH has hierarchical flower‐like structure, composing of needle‐like building blocks. After calcinations at 800°C, it converts to cubic γ‐Al2O3 with hierarchical structure retained by a topotactical process. N2 adsorption and desorption reveal that the obtained γ‐Al2O3 has a BET surface area of 101 m2/g with a narrow mesoporous size of about 13 nm and a broad macroporous‐size distributions of 200–500 nm, respectively. The as‐generated γ‐Al2O3 with hierarchical structure shows good capacities for removing Congo red from wastewater, indicating that 3D hierarchical structure has excellent adsorption ability.