SÍNTESE E CARACTERIZAÇÃO DE ÓXIDO DE ZIRCÔNIO E DE METAIS DE TRANSIÇÃO A PARTIR DE PECTINA CÍTRICA E ZIRCÔNIO

Abstract

The wide applicability of zirconium oxides makes the development of synthesis routes important in order to obtain distinct crystalline phases with lower cost. In this study, we present the synthesis and characterization of zirconium oxide and oxides mixed with transition metals (Fe, Co, Ni) obtained from citrus pectin (a polysaccharide) and zirconila nitrates and the corresponding transition metal oxides. The method used is the sol-gel route that, after the step of gelation, the gel was calcined to obtain solid. Properly powdered solids were characterized according to their structural, morphological, spectroscopic behavior and applied in dye degradation. The electronic spectra show absorption bands attributed to d-d transitions of the respective ions of transition metals used. Thermal analysis curves indicate the presence of residual pectin (organic fraction) in the solids obtained after the calcination stage (600ºC) suggesting that pectin is tightly coordinated. Yet it is identified loss of mass due to the departure of water and nitrate group, and a stabilized level before the crystallization of the oxides (temperature above 700°C) occurs. The X-ray diffraction indicate good crystallinity, but stages related to the presence of the transition metals were not identified. That is, the matrix of zirconia remains unchanged, with the incorporation of transition metals in their crystalline structure. Raman spectroscopy indicates the presence of tetragonal phase of the oxide, confirming with the data obtained by X-rays, in which runs an effective incorporation of atoms of iron, cobalt and nickel. Images of scanning electron microscopy show similar morphology and present themselves particulate, with no differences to each other. The application of the zirconia/iron oxide in the degradation of dye is shown promising according to the results obtained, because after a 60-minute period there was 90% degradation of the dye.