Fabrication of Nanosheet-Assembled Hierarchical AlOOH and γ-Al<sub>2</sub>O<sub>3</sub> Microspheres and its Application in Water Purification

Hierarchical AlOOH microspheres assembled from nanosheets were successfully synthesized via a microwave hydrothermal method, by using AlCl 3 ·6H 2 O and NaOH as raw materials and cetyltrimethyl ammonium bromide (CTAB) as a surfactant. Thermal decomposition of the AlOOH precursor at 500°C for 2h produced γ-Al 2 O 3 that maintained the precursors morphology. The products were well characterized by SEM, TEM and XRD. Finally, both hierarchical AlOOH and γ-Al 2 O 3 microspheres were used to adsorb Congo red from a water solution. The experimental results show that hierarchical AlOOH microspheres with the diameter about 1μm are assembled from nanosheets with average thickness of about 20nm. The morphology of the obtained γ-Al 2 O 3 microspheres is well preserved, and nanometer-size holes appear on the surface of the nanosheets. Both AlOOH and γ-Al 2 O 3 microspheres are very effective in the removal of Congo red pollutant from waste water which may be attributed to their textured microstructure and high specific surface area.