γ-AlOOH Nanomaterials with Regular Shapes: Hydrothermal Fabrication and Cr2O72-Adsorption

Well-defined boehmite (gamma-AlOOH) nanomaterials with regular shapes, which include nanorods, nanobelts, and nanoplates, were prepared by hydrothermal reactions of -AlOOH nanoparticles, to which H2SO4, CH3COOH, and HCl were added to regulate the shape of the products. The formation of the nanomaterials with different shapes could be attributed to adsorption of SO42, CH3COO, and Cl on the crystal planes, which affected the oriented aggregation of the raw -AlOOH nanoparticles and the growth of the aggregates. The difference in the adsorption abilities of the acidic anions resulted in the different shapes of the products. The corresponding shape-retained -Al2O3 nanomaterials were obtained after calcination. Furthermore, the differently shaped nanomaterials exhibited different adsorption capabilities for Cr2O72 in aqueous solution, and the nanobelts showed an adsorption of up to 95.5%. The exposed crystal facet of the -AlOOH nanomaterials is an important factor that affects the adsorption ability.