Synthesis of high-surface-area γ-Al ₂ O ₃ from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II)

Several types of alumina were synthesized from sodium aluminate (NaAlO ₂ ) by precipitation with sulfuric acid (H ₂ SO ₄ ) and subsequently calcination at 500°C to obtain γ-Al ₂ O ₃ . The precursor aluminate was derived from aluminum scrap. The various γ-Al ₂ O ₃ synthesized were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), adsorption-desorption of N ₂ (S _BET ) and scanning electron microscopy (SEM). XRD revealed that distinct phases of Al ₂ O ₃ were formed during thermal treatment. Moreover, it was observed that conditions of synthesis (pH, aging time and temperature) strongly affect the physicochemical properties of the alumina. A high-surface-area alumina (371 m ² g ^-1 ) was synthesized under mild conditions, from inexpensive raw materials. These aluminas were tested for the adsorption of Cd(II), Zn(II) and Pb(II) from aqueous solution at toxic metal concentrations, and isotherms were determined.