No abstract

Catalytic supports based on aluminum oxide were synthesized by the method of hybrid spheres using carboxymethylcellulose as organic precursor (template) and aluminum nitrate as inorganic precursor. The characterizations were performed by analysis of TG, XRD, FTIR, SEM and N 2 physisorption. The study of synthesis indicated that the characteristics of the biopolymer (degree of substitution and polymerization) directly influence on the limit ratio between organic and inorganic precursor in order to observe the formation of the hybrid spheres. The physicochemical properties of the final material (structure by XRD, texture by N 2 physisorption and morphology by SEM) showed a direct dependence with the biopolymer properties, indicating the versatility of this synthetic route. FTIR spectra confirm the formation of a hybrid material, comparing the pure CMC spectrum with the solids after drying. N 2 adsorption/desorption isotherm and SEM images confirm the formation of highly porous materials with a specific surface area between 50 and 162 m 2 /g.

The mixture containing alloy and oxide with iron-based phases has shown interesting properties compared to the isolated species and the synergy between the phases has shown positive effect on dye adsorption. This paper describes the synthesis of Fe2SiO4-Fe7Co3-based nanocomposite dispersed in Santa Barbara Amorphous (SBA)-15 and its application in dye adsorption followed by magnetic separation. Thus, it was studied the variation of reduction temperature and amount of hydrogen used in synthesis and the effect of these parameters on the physicochemical properties of the iron and cobalt based oxide/alloy mixture, as well as the methylene blue adsorption capacity. The XRD and Mössbauer results, along with the temperature-programmed reduction (TPR) profiles, confirmed the formation of Fe2SiO4-Fe7Co3-based nanocomposites. Low-angle XRD, N2 isotherms, and TEM images show the formation of the SBA-15 based mesoporous support with a high surface area (640 m2/g). Adsorption tests confirmed that the material reduced at 700 °C using 2% of H2 presented the highest adsorption capacity (49 mg/g). The nanocomposites can be easily separated from the dispersion by applying an external magnetic field. The interaction between the dye and the nanocomposite occurs mainly by π-π interactions and the mixture of the Fe2SiO4 and Fe7Co3 leads to a synergistic effect, which favor the adsorption.