Síntesis y caracterización de nanopartículas de óxido de cromo, partiendo de aguas residuales de curtiembre

Abstract

Industrial wastewater is an important factor in the pollution of effluents and different ecosystems on our planet. The wastewater originating in the tannery industry contains large amounts of undissolved salts, composed of heavy metals such as chromium in the form of a basic salt, and discarded without previously treating them. This work's main objective was to recover chromium present in the wastewater of the tannery "TUNGURAHUA" to synthesize and characterize chromium oxide nanoparticles. The technique used for this process was direct precipitation with ammonium hydroxide to basic chromium sulfate, performing a total of 27 tests. The variables used in the process were the change of pH with values of 9, 10, and 11, subjecting them to calcination temperatures of 400 °C, 600 °C, and 800 °C. The characterizations used were: Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). Through MEB characterization, particles of 36,540 μm and 42,651 μm were visualized. Thanks to EDS it was found that there was a percentage by mass and atom of oxygens (36.5503%; 51.7605%) and chromium (4.3348%; 1.8889%). As for DXR, planes 04 and 202 were obtained, and a rhombohedral crystal structure is found. In this context, it is concluded that the salt recovered as a result of treatment with a precipitating base together with thermodynamic techniques, can be treated to synthesize nanoparticles of trivalent chromium oxide, which was used in some industrial uses as a pigment.