Characteristics of Surface-modified Aluminum Hydroxide, Iron Oxide and Red Mud in Dissolution Process
T. M. H. Le, V. T. Nguyen, S. T. Dong and T. D. Nguyen

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Aluminum hydroxide (gibbsite) and iron oxide (hematite) are the main components of natural ores and industrial products. They are the basic raw materials for the production of aluminum and steel. Thermodynamic methods were used to study the modification of iron(III) oxide and aluminum hydroxide surfaces at different rates and conditions of dissolution. Instrumentation utilized for this study were X-ray diffraction, field emission scanning electron microscope and Brunauer, Emmett and Teller (BET) surface area analysis. Data from modified samples were evaluated using these methods for source variation with encouraging results. Experimental results indicated that after dissolving in acid, iron oxide had cracks and grooves on its surface but aluminum hydroxide’s surface had no traces. The surface-modified phenomenon was recorded in the process of making adsorbent from red mud generated from alumina production by Bayer process at Tan Binh and Tan Rai Chemical Plants. BET analysis showed that the specific surface area of red mud at Tan Binh and Tan Rai Chemical Plants dissolved in acid at a dissolution rate of 10% which increased by 50% and 90%, respectively.

Key words: Aluminum hydroxide; iron oxide; dissolution; separation; solid phase surface; adsorbent; red mud


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