Ramdhani, Eka Putra
Universitas Gadjah Mada

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Extraction of Alumina from Red Mud for Synthesis of Mesoporous Alumina by Adding CTABr as Mesoporous Directing Agent

Indonesian Journal of Chemistry Vol 18, No 2 (2018)
Publisher : Universitas Gadjah Mada

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Abstract

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.

Synthesis of Amorphous Aluminosilicates from Bintan’s Red Mud as Alumina Source

Indonesian Journal of Chemistry Vol 18, No 4 (2018)
Publisher : Universitas Gadjah Mada

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Abstract

Red mud is a generated by-product in alumina production from bauxite ore. In this study, Bintan’s red mud has been used as alumina and silica source to synthesize amorphous mesoporous aluminosilicates material. Alkali fusion method with a NaOH/red mud ratio 0.8; 1.0; 1.2; 1.4 and 1.5 followed by hydrolysis method was used to extract dissolved alumina and silica from red mud. Synthesis of amorphous aluminosilicates by hydrothermal method was conducted at 80 °C for 24 h. Cetyltrimethylammonium bromide (CTABr) was added as the structure directing agent. Aluminosilicate products were characterized using FTIR spectroscopy (Fourier Transform Infra-Red Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and nitrogen adsorption-desorption. XRD and SEM result shows that the product was amorphous with low uniformity in terms of surface morphology and particle size. Nitrogen adsorption-desorption profile shows that all aluminosilicates products has a meso pore structure, confirmed by the highest pore distribution at 3.05–17.70 nm. The highest surface area and pore volume were obtained in ASM 0.8 (NaOH/red mud ratio = 0.8) i.e. 177.97 m2/g and 1.09 cm3/g, respectively.