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  • Artigo
    Biodiesel production from vegetal oil and ethanol via transesterification in supercritical conditions
    (2023-08-03) SIDI NETO, V.; DERENZO, S.; MARIN, M. P. DE A.; Luis Novazzi ; João Guilherme Rocha Poço
    © 2023, The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química.Biodiesel, which is derived from renewable feedstock, has potential to replace fossil diesel. In this study, biodiesel production was carried out through the transesterification of soybean oil with ethanol (anhydrous and hydrated) under supercritical conditions in a batch reactor, with a temperature range of 280–340 °C and an oil/alcohol molar ratio of 1:40. The effects of both anhydrous and hydrated ethanol on the reaction were evaluated, as well as the direct esterification of oleic acid to produce ethyl ester. A first-order reversible kinetic model was proposed to describe the transesterification process. The results showed a good agreement between experimental data and the model. It was observed that temperature has an important effect on ester yield and hydrated ethanol improved this yield. After 120 min of reaction time at 310 °C with hydrated ethanol, transesterification led to 89.7% of ethyl ester. When compared to anhydrous ethanol, forward rate constants of hydrated ethanol suggested that water may have a catalytic effect on transesterification. Although the transesterification of soybean oil and ethanol under supercritical conditions is nearly irreversible at 280 °C, the reaction is limited by equilibrium at temperatures equal to or higher than 310 °C.
  • Artigo
    Effects of caramelization and Maillard reaction products on the physiology of Saccharomyces cerevisiae
    (2023-01-05) ELIODORO, K. P.; PENNACCHI, C.; DE GOIS E CUNHA, G. C.; Andreia de Araújo Morandim Giannetti; GIUDICI, R.; BASSO, T. O.
    © 2023 British Mycological SocietyThe thermal treatment the sugarcane juice undergoes during its processing alters the medium's chemical composition through the so-called Maillard reactions and its products, which can affect the alcohol-producing yeast's physiology in steps following the processing. This study aims to describe and characterize the reactivity of the primary amino acids present in sugarcane with sucrose, as well as demonstrate the physiological effects of the reaction's products on the yeast Saccharomyces cerevisiae. The main amino acids in sugarcane (glutamine, asparagine, and aspartic acid) were chosen to be reacted with sucrose under similar conditions to the industrial sugarcane processing (pH 5 and temperature 100–120 °C). The physiological effect of Maillard and caramelization reaction on the S. cerevisiae CEN.PK-122 and PE-2 strains were tested in microplate experiments using a modified mineral media containing both the reacted and unreacted amino acid-sucrose systems and four modified synthetic molasses media. The results have shown that the presence of any amino acids drastically increases product formation. Furthermore, among the amino acids, aspartic acid was the most reactive. Meanwhile, asparagine and glutamine had similar results. In S. cerevisiae physiology, aspartic acid had the most significant effect on culture growth by reducing the maximum specific growth rate and optical density. The increase in the Maillard product concentration for synthetic molasses also evidenced the inhibitory effect on yeast growth compared to media in the absence of these products. We conclude that this initial investigation clarifies the inhibitory effect of the Maillard products on yeast physiology.
  • Artigo
    Direct oxidation of 3-picoline (3-methyl-pyridine) to nicotinic acid with pure HNO3
    (2023-07-17) GOMES, E. L.; FREITAS, D. A. DE; Rodrigo Condotta; João Guilherme Rocha Poço
    © 2023, The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química.Nicotinic acid (NA) was synthesized by directly oxidizing 3-methylpyridine (3MP) with nitric acid. The reaction was performed in an instrumented PARR reactor. The effect of temperature (165 to 195 °C) and the molar composition of the initial reactive mixture were studied. Molar conversions of 3-methylpyridine ranged from 36 to 90%, with a yield of NA ranging from 31 to 62%. Better selectivities occur at low-time reactions and low conversion rates. At the same time, the HNO3 excess and temperature considerably affect 3MP conversion rate and NA yield rather than selectivity, especially at 180 °C, whereas an invariable selectivity of 80% was observed.
  • Artigo
    Measurement and correlation of high-pressure volumetric properties of binary mixtures of 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]) with alcohols
    (2023-10-05) HAUK, D. B.; Ricardo Torres; DANGELO, J. V. H.
    © 2023 Elsevier LtdNew experimental data for density-pressure–temperature measurements of binary mixtures of {1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]) + methanol, or + ethanol or + 1-propanol} have been measured using a vibrating tube densimeter at temperatures from T = (298.15 to 308.15) K and pressure range p= (0.1 – 40) MPa. The experimental density results have been correlated by the Tait-Tammann equation with the temperature and composition dependence parameters. The effects of the increase in the alkyl chains of the alcohols, temperature, and pressure on the density and volumetric properties have been analyzed. Moreover, the Extended Real Associated Solution Model (ERAS Model) has been used to correlate the experimental behavior of the excess molar volume of the studied systems.
  • Artigo
    Fe3O4 nanoparticles and Rhizobium inoculation enhance nodulation, nitrogen fixation and growth of common bean plants grown in soil
    © 2020 Elsevier B.V.The effects of Fe3O4 nanoparticles (NPs) and Rhizobium inoculation on nodulation, nitrogen fixation and plant growth of common bean (cv. Red Guama, Phaseolus vulgaris) plants were investigated in growth chambers. Plants were exposed to: Fe3O4 NPs (2000 mg/L) (T1), Rhizobium inoculation (T2) and Fe3O4 NPs + Rhizobium inoculation (T3); non-treated plants were considered as controls. Harvested 35-day-old treated plants showed improved symbiotic performance including increased nitrogenase activity (51.2–90.7%), nodule leghaemoglobin (44.8–80.9%) and iron content (83.4–84.2%), number of active nodules per plant (58.7–122%) and nodule dry weight (40.2–70.6%). This resulted in enhanced symbiotic nitrogen fixation,and increased shoot (26.5–50.2%) and root (24.1–48.2%) total nitrogen content in treated plants in comparison with the controls. The best result was obtained using treatment T3. Furthermore, Fe3O4 NPs were taken up by bean plants in treatments T1 and T3, and these accumulated in their organs, including in nodules. All treatments led to an increase in root (51.9–79.8%) and shoot (27.5–52.7%) lengths, in leaf area (10.9–16.8%) and in root (10.1–17.8%), stem (9.8–12.7%) and leaf dry weight (8–17.3%) compared to control plants. Thus applied treatments have the potential to improve common bean plant growth through enhancement of nodulation and nitrogen fixation during vegetative growth.This study also provides strong evidence that the presence Fe3O4 NPs in nodules improves the symbiotic performance between Rhizobium (leguminosarum CF1 strain) and the common bean plant, due to enhanced nodulation and nitrogen fixation.