Synthesis of alumina nanosheets via supercritical fluid technology with high uranyl adsorptive capacityElectronic supplementary information (ESI) available: The TEM images of a boehmite precursor after 6 h and 48 h and the corresponding calcined products. See DOI: 10.1039/c2nj40514h

Supercritical carbon dioxide is beneficial to the synthesis of superior ultrafine and uniform materials due to its high chemical stability, low viscosity, high diffusivity, and "zero" surface tension. γ-Alumina nanosheets were obtained by a simple hydrothermal route in the presence of supercritical carbon dioxide. XRD, FTIR, SEM, TEM and nitrogen sorption isotherm were employed to characterize the samples. Alumina as-prepared has a high specific surface area of up to 200 ± 6 m 2 g −1 , which presents a high adsorption capacity (4.66 ± 0.02 mg g −1 ) for uranyl ions from aqueous solution. Furthermore, the adsorption process was found to be endothermic and spontaneous in nature. γ-Alumina nanosheets with a high surface area of 200 ± 6 m 2 g −1 were obtained via supercritical fluid technology. The product has a high adsorption capacity of 4.66 ± 0.02 mg g −1 for uranyl ions.