Extraction of alumina from red mud for synthesis of mesoporous alumina by adding CTABr as mesoporous directing agent

Mines in Bintan were producing bauxite for many years. The production process of bauxite to alumina produced much red mud. From X-ray Fluorescence (XRF), alumina content on Bintan’s red mud was 28.87 wt.%. This research was studying on the extraction alumina from red mud with reduction of hematite (Fe₂O₃) and desilication processes. After extraction process alumina was collected about 52.89 wt.%. Synthesis of mesoporous alumina from red mud using sol-gel method at the room temperature for 72 h with cetyltrimethylammonium bromide (CTABr) as mesoporous directing agent. The CTABr/Al-salt ratio, i.e. 1.57; 4.71 and 7.85 with the sample code of AMC-1, AMC-3, AMC-5, respectively. The product was calcined at 550 °C for 6 h. The synthesized materials were characterized by X-ray Diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), and N₂ adsorption-desorption techniques. XRD pattern of AMC-1, AMC-3, and AMC-5 showed that all synthesized materials have amorphous phase. The morphology were wormhole aggregate that were showed by SEM and TEM characterization. N₂ adsorption-desorption characterization showed the distribution of pore size of about 3.2 nm. The highest surface area and pore volume were obtained in solid-solid ratio CTABr/GM-AL by 1.57 (AMC-1) i.e. 241 m²/g and 0.107 cm³/g, respectively.