Obtenção, caracterização e estudo do comportamento térmico de quelatos mistos de Ce e Mn com 8-hidroxiquinolina

Abstract

In this work the results of obtaining, characterizing and thermal behavior of mixed chelates of Cerium and Manganese with 8-hydroxynoline are presented. For the formation of the chelates, aqueous solutions of the nitrates of Cerium and Manganese and a solution of 8q dissolved in acetone were used, with rising of the pH by the addition of ammonium hydroxide. The co-precipitated was characterized by Colorimetry by CIELab system, indicating that its color is brown; by Fourier-transform infrared absorption spectroscopy (FTIR), confirming the chelation of the metals through the C-O and C-N bands, and suggesting excess chelating material through the OH bands; and by X-ray diffractometry (XRD), confirming the presence of the individual chelates of Cerium and Manganese, and excess of 8q in the co-precipitated. The thermogravimetric (TGA) and differential thermal analysis (DTA) were performed in different heating and atmosphere ratios, indicating that, independently of the heating or atmosphere ratio, there were three main events: water loss, excess elimination of the co-precipitated binder and the oxidative decomposition of the co-precipitate. The oxides obtained in muffle at the heating rate of 20 °C min-1 at final temperatures of 600, 700, 800 and 900 ° C, were characterized by XRD as a mixture of CeO2 and Mn3O4, for the most part; and by scanning electron microscopy (SEM), it was found that the oxides tend to be organized through the sintering process.