ALUMINATOS COLORIDOS OBTIDOS A PARTIR DE DESCARTES DE ALUMÍNIO METÁLICO

Abstract

In this study, we prepare colored aluminates using metallic aluminum tailings (soda can seal) as a precursor for its application as synthetic inorganic pigments. For this, the acid digestion (HCl) of the metal was carried out with the purpose to obtain (aluminum) Al3+ ions. To obtain colored pigments, aliquots containing aluminum in solution were doped (10% m/m) with transition metal chloride salts (Cr, Mn, Fe, Co and Ni), precipitated by pH control using a strong base (NaOH) and calcination at 1000 °C. The pigments obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy and eletronic spectroscopy (UV-Vis). Colorimetric measurements were performed according to the CIEL*a*b* colorimetry system. The pigments after calcination presented aluminate phases, characterized by the insertion of colored ions in the white matrix structure and a mixed iron and aluminum oxide, data that were corroborated by the absorption spectra in the visible region. The colorimetry presented cobalt aluminate as the most saturated pigment in color. Pigments were obtained in all colorimetric quadrants, in other words, in several colors. After dispersion in paint and application in plaster, the pigments showed color stability, since after one year of application none of the samples showed a very strong color variation. In this way, the use of colored aluminates from reused metallic aluminum as synthetic inorganic pigments was shown to be feasible.