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A mathematical model of an isothermal semibatch bubble reactor has been developed to describe the esterification reaction of free fatty acids with superheated alcohol vapor. The proposed model accounts for the effects of mass transfer followed by chemical reaction in the liquid phase. The fluid physical properties are calculated by published correlations, and the partition coefficient of alcohol vapor was estimated based on thermodynamic models of vapor−liquid equilibria. Experimental data of acid-catalyzed esterification of oleic acid with superheated ethanol vapor at different conditions of temperature and gas superficial velocities were used to estimate the liquid side mass transfer coefficients and kinetic parameters. The results obtained showed that the model satisfactorily fits the experimental data for all operating conditions and was also able to simulate and predict experimental results for intermediate conditions with a coefficient of determination R 2 of 0.987. In addition, the estimated values of the mass transfer coefficient agreed with data reported in the literature for gas−liquid reactors.

<p><span style="font-size: medium;">A industrialização do principal resíduo da banana é a sua casca que compreende</span><span style="font-size: medium;"> aproximadamente 45% do peso total deste fruto</span><span style="font-size: medium;">. O trabalho teve como objetivo analisar o aproveitamento da casca de banana madura na alimentação animal em forma de pellet. O enriquecimento das cascas de banana foi realizado em quatro tratamentos a seguir:  T</span>_{<span style="font-size: small;">1</span>}<span style="font-size: medium;"> = Casca de banana na forma <em>in natura</em>; T</span>_{<span style="font-size: small;">2</span>}<span style="font-size: medium;"> = Casca de banana + 2% de levedura; T</span>_{<span style="font-size: small;">3</span>}<span style="font-size: medium;"> + Casca de banana + 2% de levedura + 1% de ureia; T</span>_{<span style="font-size: small;">4</span>}<span style="font-size: medium;"> + Casca de banana + 2% de levedura + 2% de ureia. Foram analisadas as características químicobromatologica dos tratamentos na forma<em> in natura </em>e processada, obtendo-se valores proteicos de 5,28%; 12,33%; 12,33% e 24,09%, respectivamente. O enriquecimento dos pelletes de casca de banana com a levedura e/ou ureia aumentaram substancialmente o valor proteico destes em relação deste na forma<em> in</em> <em>natura.</em> Os tratamentos que foram adicionados os níveis de ureia (1 % e 2%) reduziram os conteúdos de FDN, FDA, CHOT, CNF, CEL e HC nos <em>pelletes</em>, porém deferiram entre si (P&lt;0,005). Para os teores de MS e PB houve um aumento significativo (P&lt;0,005) em relação aos <em>pelletes</em> na forma <em>in natura</em>, resultando em uma elevada eficiência da bioconversão do processo.</span></p><p> </p>

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In the present study, the transesterification of soybean oil with ethanol under supercritical conditions was investigated using a packed-bed tubular reactor. The experiments were performed with an oil/alcohol molar ratio of 1:40, a pressure of 15 MPa, and different conditions of temperature (573–673 K), flow rate (0.5–1.0 mL/min), and bed porosity (0.32–1.0). A phenomenological model was developed to describe and analyze the results. The highest ester yield (98.99%) was obtained for the lower bed porosity (0.32), under 673 K and 0.5 mL/min with a residence time of 5.44 min. The kinetic and dispersion coefficients were estimated using the particle swarm optimization algorithm, and the model fitted the experimental data with an R 2 coefficient of 0.97. The proposed kinetic model followed the behavior of the Arrhenius equations. Low values of dispersion were observed under conditions of lower flow rate and porosity. An analysis of the model allowed us to verify that the increase of the ester yield produced occurs at small values of the Reynolds number and high Peclet numbers.