Ceramics-Silikáty 50 (1) 22-26 (2006)

Hydrous aluminium-oxides prepared by homogeneous precipitation from aluminium(III)sulphate with urea

J. Lukáč, S. Bakardjieva, V. Štengl, L. Szatmáry, J. Šubrt

Easily filtrated alumina-oxides spherical precursors were prepared by homogenous precipitation from aluminium(III) sulphate with urea. Urea was employed as precipitation agent. X- Ray powder diffraction (XRD) spectra identified three different phases, namely: a-boehmite, boehmite and hydrobasaluminite. The morphology of prepared samples was observing by SEM (scanning electron microscopy) equipped with EDX (energy dispersive analysis by X-rays). The spherical clusters were examined at small concentration and the hydrobasaluminite islands were observed at the largest concentration of reagents. The microstructure characteristics were obtained by BET (Brunauer-Emmett-Teller) and BJH (Barret-Joyner-Halanda) methods. BET in wide range from 6 to 142 m²/g and the all kinds of porous distribution were acquired, respectively. These methods showed that relationship between phase structures and microstructure exists.

Keywords: Urea, Homogeneous precipitation, a-boehmite, Boehmite, Hydrobasaluminite