Authors:J. Maul, A. S. Brito, A. L. M. de Oliveira, S. J. G. Lima, M. A. M. A. Maurera, D. Keyson, A. G. Souza, and I. M. G. Santos
Copper monoxide (CuO) was successfully obtained by microwave-assisted hydrothermal method, using different conditions—in a solution without base, in a solution alkalinized with NaOH or with NH4OH. The powders were analyzed by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, UV–Visible spectroscopy, and scanning electronic microscopy. XRD results showed that CuO was obtained with monoclinic structure and without secondary phases. Thermal analysis and infrared spectra indicated the presence of acetate groups on the powder surface. TG curves also showed a mass gain assigned to the Cu(I) oxidation indicating that a reduction possibly occurred during synthesis. The high and broad absorption band in the UV–Vis spectroscopy from 250 to 750 nm indicated the coexistence of Cu(II) and Cu(I), confirming the Cu(II) reduction, inside the CuO lattice. It was also possible to confirm the Cu(II) reduction by a displacement of the Me–O vibration bands observed in the IR spectra at around 500 cm−1.
Authors:K. L. G. V. Araújo, P. S. Epaminondas, M. C. D. Silva, A. E. A. de Lima, R. Rosenhaim, A. S. Maia, L. E. B. Soledade, A. L. Souza, I. M. G. Santos, A. G. Souza, and N. Queiroz
Physicochemical and thermal analyses were undertaken to evaluate the influence of the temperature on the oxidation of sea fish oil once its polyunsaturated fatty acids deteriorate rapidly. Fish oil displayed four decomposition steps in synthetic air atmosphere and only one step in nitrogen atmosphere. The first step started at 189 and 222 °C for oxidizing and inert atmospheres, respectively. An OIT value of 53 min was measured at 100 °C. After the degradation process the peroxide index and the iodine index reduced from 35.38 to 9.85 meq × 1000 g−1 and from 139.79 to 120.19 gI2 × 100 g−1, respectively. An increase of the free fatty acids amount from 0.07 to 0.17% was observed while viscosity increased from 57.2 to 58.0 cP. Absorption at 272 nm also increased. The thermogravimetric and spectroscopic techniques are reproducible and versatile being an option for characterization of edible oil oxidation.
Authors:Ingrid C. R. Costa, Ivaldo Itabaiana Jr., Marcella C. Flores, Ana Clara Lourenço, Selma G. F. Leite, Leandro S. de M. e Miranda, Ivana C. R. Leal, and Rodrigo O. M. A. de Souza
The use of glycerol derived from biodiesel industry is an important development to add value to this actual waste. Several products can be obtained from glycerol, but acetins are very interesting molecules with a wide range of applications in pharmaceutical, cosmetics, food, and fuel industry. Herein we report our results on biocatalyzed batch and continuous-flow process for valorization of glycerol derived from biodiesel industry towards acetin production. Excellent results can be obtained with different selectivities depending on the nature of glycerol used and reaction conditions being able to produce monoacetin, diacetin, or triacetin depending on the reaction condition.