Synthesis and characterization of pyroaurite-type material at room temperature employing bauxite residues from Amazon Region

The synthesis of hydrotalcite-type material from bauxite residues from Juruti mine (Pará State, northern Brazil) is presented. The residues and the final product were characterized by X-Ray Diffraction (XRD), Thermogravimetric analysis and Scanning Electron Microscopy (SEM). According to the results obtained, although residues have been employed as starting material, pure hydrotalcite could be synthesized with rhombohedral (R3-m) structure-like and 7,82 Å interlayer spacing. The unit cell parameters were obtained as a=3.130(7)Å, c=23.47(6)Å, as well as size crystal (31 nm) by Scherrer Equation. The thermal behavior of hydrotalcite could be divided into four main decomposition steps (TG-DTA curves) related to the loss of interlamellar water, decomposition of OH- groups and collapse of the hydrotalcite structure. The material exhibited morphology in the form of plates and small agglomerates around 10 m.