Adsorption performance and mechanism of Al2O3 aerogels towards aqueous U(VI) using template synthesis technology

Abstract

The stable Al2O3 aerogels with low density were prepared via template synthesis method using different template materials and the as-prepared Al2O3 aerogels inherited the morphology of template materials, which showed different network structures. Meanwhile, the U(VI) removal on the Al2O3 aerogels from water was investigated. The kinetic analyses indicated that the U(VI) removal reached equilibrium within 180 min (pH = 7, C0 = 10 mg/L, m/V = 0.1 g/L and T = 298 K). The calculated maximum adsorption quantity of Al2O3-C, Al2O3-P and Al2O3-D aerogels at room temperature from Langmuir model reached 814.27, 736.67 and 529.15 mg/g, respectively (pH = 7, m/V = 0.1 g/L and T = 298 K). It could be seen that the Al2O3 aerogels possessed excellent adsorption performance to U(VI). Moreover, all U(VI) ions were almost removed completely on Al2O3 aerogels under the low concentration of U(VI) and the adsorption efficiency of all the regenerated adsorbents nearly remained unchanging after five circulation of adsorption-desorption. The results reflected that the Al2O3 aerogels would be potential adsorbents for the removal of U(VI). To clarify the interaction mechanism between U(VI) and Al2O3 aerogels, the analyses of XPS, FT-IR and XRD were carried out. Based on the results, the hydroxyl groups performed a central role to combine the U(VI) species and Al2O3 aerogels.