Engenharia Química

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Characterization of clarified medium from submerse and semisolid cultivation of Aspergillus awamori NRRL 3112 by size-exclusion chromatography
(1999) MINAMI, N.; LUCARINI, Adriana Celia; KILIKIAN, Beatriz Vahan
Thermodynamics of Binary Liquid Mixtures: Application of the Prigogine-Flory-Patterson Theory to Excess Molar Volumes of Acetonitrile + 1-Alkanols Systems
(2004) TORRES, Ricardo Belchior; FRANCESCONI, Artur Zaghini; VOLPE, Pedro Luiz Onófrio
Stereoselective preparation of conjugated E-enynes from E-vinylic tellurides and terminal alkynes via Sonogashira cross-couplingElectronic supplementary information (ESI) available: spectroscopic data for all new compounds as well as detailed experimental procedures. See http://www.rsc.org/suppdata/ob/b4/b401059k/
(2004) ZENI, Gilson; ALVES, Diego; PENA, Jesus Marcelo; Braga, Antonio L.; Stefani, Helio A.; Nogueira, Cristina W.
Purification of glucose oxidase from Aspergillus niger by liquid-liquid cationic reversed micelles extraction
(2005) FERREIRA, Luis Fernando Peffi; Taqueda, M. H.; VITOLO, M.; CONVERTI, A.; Pessoa, A.
Laboratório de Física Moderna do Centro Universitário da FEI
(2005-09-05) GUAZZELLI, Marcilei Aparecida; SANTOS, Roberto; BARBETA, Vagner
Volumetric properties of binary mixtures of (water + organic solvents) at temperatures between T = 288.15 K and T = 303.15 K at p = 0.1 MPa
(2006) Torres R.B.; Marchiore A.C.M.; Volpe P.L.O.
In this work, densities of binary mixtures of {water + formamide (FM), or + N,N-dimethylformamide (DMF), or + dimethylsulfoxide (DMSO), or + N,N-dimethylacetamide (DMA), or + 1,4-dioxane}, have been determined under atmospheric pressure as a function of composition and temperature using a vibrating-tube densimeter. The temperatures studied were T = (288.15, 293.15, 298.15, and 303.15) K. The excess molar volumes ( VmE ), calculated from density data, are negative over the whole mole fraction range for the temperature range studied. The VmE values have been fitted to Redlich-Kister polynomial equation and others volumetric properties were calculated. The partial molar volumes at infinite dilution of each component ( over(V, ̄)i∞ ) have been determined using three different methods. © 2005 Elsevier Ltd. All rights reserved.
Surface energy and thermodynamic stability of γ-alumina: Effect of dopants and water
(2006-04-04) CASTRO, R. H, R.; USHAKOV, S. V.; GENGEMBRE, L.; GOUVEA, D.; NAVROTSKY, A.
Retaining large surface areas in alumina powders during high-temperature annealing is a major challenge in applications as catalyst supports and ceramic precursors. This is because the alumina surface area drastically decreases with transformation from the γ modification (defect spinel structure) into the a modification (corundum structure). The objective of this work is to show the thermodynamic basis of using additives, such as Zr and Mg, to control the γ-Al 2O 3 surface and bulk energetics and to manipulate the transformation temperature and surface area. These additives are observed to change the pattern of phase transformation and densification. Direct measurements of heats of solution in a lead borate melt of pure and doped alumina as a function of surface area enabled us to experimentally derive trends in the surface energies of hydroxylated surfaces. Accounting for heats of water adsorption measured on pure and doped alumina surfaces allowed us to delineate the thermodynamic effects of hydration on surface energies. Zr-doped γ-alumina showed a higher energy of the hydroxylated surface than did pure γ-alumina but showed a lower energy of the anhydrous surface. Mg addition does not change surface energies significantly but decreases the energetic instability of the bulk γ phase. © 2006 American Chemical Society.
Volumetric properties of binary mixtures of acetonitrile and alcohols at different temperatures and atmospheric pressure
(2007) Torres R.B.; Francesconi A.Z.; Volpe P.L.O.
In this work, densities and excess molar volume data of binary mixtures of acetonitrile + methanol, or + ethanol, or + 1-propanol, or + 1-butanol as a function of composition, under atmospheric pressure and at 288.15, 293.15, 298.15 and 303.15 K have been used to calculate partial molar volumes (V-i), excess partial molar volumes (V-iE) and apparent molar volumes (Vφ{symbol}i) of each component. The partial molar volumes at infinite dilution (V-i∞) have been determined using three different methods. © 2006 Elsevier B.V. All rights reserved.
Volumetric properties of binary mixtures of ethers and acetonitrile: Experimental results and application of the Prigogine-Flory-Patterson theory
(2008) Torres R.B.; Ortolan M.I.; Volpe P.L.O.
In this work, densities of binary mixtures of {acetonitrile + di-n-butyl ether (DNBE), or + tetrahydrofuran (THF), or + 1,4-dioxane (DIO), or + di-isopropyl ether (DIPE)}, have been determined under atmospheric pressure as a function of composition and temperature using a vibrating-tube densimeter. The temperatures studied were T = (288.15, 293.15, 298.15, and 303.15) K. The excess molar volumes (VmE), calculated from density data, are negative over the whole mole fraction range for the temperature range studied. The partial molar volumes at infinite dilution of each component (over(V, -)i∞) have been determined using three different methods. The experimental results have been used to test the applicability of the Prigogine-Flory-Patterson (PFP) theory. © 2007 Elsevier Ltd. All rights reserved.
Volumetric behaviour of binary mixtures of (trichloromethane + amines) at temperatures between T = (288.15 and 303.15) K at p = 0.1 MPa
(2008) Magalhaes J.G.; Torres R.B.; Volpe P.L.O.
In this work, densities of binary mixtures of {trichloromethane (TCM) + n-butylamine (n-BA), or + s-butylamine (s-BA), or + diethylamine (DEA), or + triethylamine (TEA)} have been determined under atmospheric pressure as a function of composition and temperature using a vibrating-tube densimeter. The temperatures studied were T = (288.15, 293.15, 298.15, and 303.15) K. The excess molar volumes (VmE), calculated from density data are negative for all studied systems and the negative deviations follow the sequence: TEA > DEA > s-BA > n-BA. Negative values of VmE for binary mixtures were attributed to the formation of hydrogen bonding and of a charge transfer complex between TCM and amines and to structural effects. The partial molar volumes at infinite dilution of each component (over(V, -)ioo) have been determined using three different methods. © 2008 Elsevier Ltd. All rights reserved.
Volumetric properties of binary mixtures of dichloromethane and amines at several temperatures and p = 0.1 MPa
(2008) Torres R.B.; Hoga H.E.
In this work densities of binary mixtures of {dichloromethane (DCM) + n-butylamine (n-BA), or + s-butylamine (s-BA), or + t-butylamine (t-BA), or diethylamine (DEA), or + triethylamine (TEA)}, have been determined under atmospheric pressure as a function of composition and temperature using a vibrating-tube densimeter. The temperatures studied were T = 288.15, 293.15, 298.15 and 303.15 K. The excess molar volumes (VmE), calculated from density data, are negative for the (DCM + t-BA, or + DEA, or + TEA) mixtures and present a sigmoid curve for the (dichloromethane + n-BA, or + s-BA) mixtures. The partial molar volumes at infinite dilution of each component (V{combining overline}i∞) have been determined using three different methods. © 2008 Elsevier B.V. All rights reserved.
Possible indirect measurement of diffusion coefficient from migration kinetic essay of food packaging
(2008-09-10) MANZOLI, J. E.; LEMOS, C.; PANZARINI, L. C. G. A.; FÉLIX, J. S.; MONTEIRO, M.
Diffusion coefficient is an important quantity that affects any migration process on food or nutritional systems. Special care has to be done to migration of undesirable substances from packaging into foods, if the diffusion is the only process involved in mass transfer. The Fick's equation resolution permits to describe the kinetic of migration from polymer packaging into food or simulant, once it was given the correct contour and initial conditions. Another important quantity is the partition coefficient, which quantifies the relation between the final or equilibrium concentrations in polymer and that in the food or simulant. Here it is proposed a simple procedure, based on numerical resolution of the Fick's equation, where the diffusion coefficient could indirectly be measured, if the kinetic of migration had been measured and the partition coefficient is known.
Intrapopulacional variability of dihydrochalcone, chromenes and benzoic acid derivatives from leaves of Piper aduncum L. (Piperaceae)
(2009) GIANNETTI, Andreia de Araujo Morandim; CAVALHEIRO, Alberto José; KATO, Massuo Jorge; BOLZANI, Vanderlan da Silva; FURLAN, Maysa
Volumetric properties of chloroalkanes + amines mixtures: Theoretical analysis using theERAS-Model
(2009) Torres R.B.; Hoga H.E.; Magalhaes J.G.; Volpe P.L.O.
In this study, experimental data of excess molar volumes of {dichloromethane (DCM), or trichloromethane (TCM) + n-butylamine (n-BA), or +s-butylamine (s-BA), or +t-butylamine (t-BA), or +diethylamine (DEA), or +triethylamine (TEA)} mixtures as a function of composition have been used to test the applicability of the extended real associated solution model (ERAS-Model). The values of the excess molar volume were negative for (DCM + t-BA, or +DEA, or +TEA and TCM + n-BA, or +s-BA, or +DEA, or +TEA) mixtures and present sigmoid curves for (DCM + n-BA, or +s-BA) mixtures over the complete mole-fraction range. The agreement between theoretical and experimental results is discussed in terms of cross-association between the components present in the mixtures. © 2009 Springer Science+Business Media, LLC.
Risk analysis and environmental impact analysis in a chemical processing facility
(2009-01-05) Maristhela Passoni de Araújo Marin; TAMBOURGI, E. B.
The present work provides a method of risk analysis in chemical processing facilities, which consists primarily of the following steps: description and study of the system, hazard analysis and identification, identification of the accidental scenarios, calculation of the consequences of the scenarios and risk characterization. To illustrate the application of the method, an uranium hexafluoride production facility was selected. The main hazards identified were: fire, explosion, spill of toxic chemical substances and ground contamination due to problems in the waterproof blanket of the waste contention bund. Some cases of environmental impact due to uranium hexafluoride (UF6) release were quantitatively analyzed for different scenarios, considering two categories of atmospheric stability: Pasquill D and Pasquill F. It was found that the impact which reached a great external area around the plant corresponded to the condition of atmospheric stability F. © 2009 Elsevier B.V. All rights reserved.
Optimal control of heat exchanger networks
(2009-01-05) Luis Novazzi; ZEMP, R. J.
Energy integration among chemical process streams can lead to quite complex heat exchanger networks (HEN) with difficulties in terms of control. In the HEN, the control system primary objective is to keep outlet stream temperatures in a specified range. This objective can be achieved by manipulating bypasses in the exchangers or heat loads in coolers or heaters, which results in a positive degree of freedom, since the number of possible manipulated variables is greater than the number of controlled variables. Thus, a secondary control objective can be set: minimization of utility consumption. In this work HEN dynamics and steady state aspects were addressed with the aim of proposing a control strategy that minimizes utility consumption and satisfies imposed restrictions. With the tools developed in this work it was proposed a feedforward optimal control strategy, which consisted in the minimization of a steady state objective function, connected to utility consumption and subjected to constraints in outlet stream temperatures. The suggested approach is an interesting one since rigid or flexible control objectives can be set. The solution of the minimization problem resulted in optimal bypasses positions in the HEN, which were dynamically implemented using a ramp function and a step function. It was verified that ramp implementation was better, with tolerable dynamic violations. © 2009 Elsevier B.V. All rights reserved.
Intraspecific variability of dihydrochalcone, chromenes and benzoic acid derivatives in leaves of Piper aduncum L. (Piperaceae)
(2009-05-18) Andreia de Araújo Morandim Giannetti; KATO, M. J.; CAVALHEIRO, A. J.; FURLAN, M.
Chemical analysis carried out in leaves of 18 specimens of Piper aduncum L. (Piperaceae) occurring at Ripasa Reserve, Araraquara, SP, Brazil indicated two distinct populations when investigated over a period of 14 months (January 2000 to February 2001) and then submitted to cluster analysis. The two groups were characterized by accumulation of prenylated benzoic acids, chromenes and dihydrochalcone, respectively. A total of seven compounds were identified by HPLC analysis and compared with standards including two prenylated benzoic acid [aduncumene (1) and 3-(3′-7′-dimethyl-2′-6′-octadienyl)- 4-methoxy-benzoic acid (5)], four chromenes [methyl 2,2-dimethyl-8-(3′- methyl-2′-butenyl)-2H-1-chromene-6-carboxylate (4), methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate (2b), methyl 8-hydroxy-2,2-dimethyl-2H- 1-chromene-6-carboxylate (3) and 2,2-dimethyl-2H-1-chromene-6-carboxylic acid (2a)] and one dihydrochalcone [2′,6′-dihydroxy-4′-methoxy- dihydrochalcone (6)]. © 2009 Academic Journals.
Multivariable control of a heat exchanger with bypasses
(2009-07-15) Delatore, F.; DA CRUZ, J. J.; Fabrizio Leonardi; Luis Novazzi
A myriad of different multivariable control techniques, ranging from the simplest isolated PID controllers to the most sophisticated model predictive controls, are presented in the literature and applied to chemical plants. This work intends to present an intermediate control solution between the simplest and the most complex control design, with a relative simplicity, in combination with a superior performance when compared to traditional PID controllers. The proposed strategy, based on a Linear Quadratic Regulator (LQR), was applied to a heat exchanger with bypasses, which is a typical equipment in industries' processes. Even though the LQR is relatively straightforward to design, with a simple tuning procedure, some simulations' results demonstrated that the proposed approach leaded to a reasonable control performance, i.e., process variables became almost totally decoupled, no offset was observed and the output responses presented an small time constant.
Use of hydrodynamic cavitation as an alternative for biodiesel production
(2009-08-30) SANTOS, S. L. DOS; FERREIRA, M. S.; Maristhela Passoni de Araújo Marin; Luis Novazzi
© 2009 by ABCM.Biodiesel is known as an alternative to conventional petrodiesel because of its renewability and better combustion performance, in addition to reducing emissions, harmful to the environment. Biodiesel production consists on the transesterification of triglycerides with an alcohol and the reaction is affected by the alcohol type, temperature, molar ratio of alcohol to oil and catalyst type and amount. Since this reaction is a heterogeneous one, reagent mixing is also of crucial importance and traditionally the blending is carried out by using mechanical mixers. In this work a different approach is proposed, where the mixing is induced by hydrodynamic cavitation provoked by an orifice plate connected to the suction of a centrifugal pump. Biodiesel production was carried out at 45°C with a 1:8 molar ratio of soybean oil to ethanol. It was observed that the method assisted by hydrodynamic cavitation promotes the enhancement of biodiesel yield in comparison to the conventional method that uses mechanical stirring. In comparative tests carried out from 0 to 40 minutes, the hydrodynamic cavitation always showed conversion rates larger than the mechanical agitation. Although specific energy consumption in biodiesel production is slightly higher for hydrodynamic cavitation when compared to conventional mechanical mixing, it was observed that in the alternative approach the equipment employed is simple and has a low acquisition cost, showing that it has a great potential to be scaled up and used in industrial processes.
Calorimetric measurement of the interface energy of pure and calcium doped magnesium oxide
(2009-10-29) CASTRO, R.; Ricardo Torres; GOUVEA, D.
Interface energetics is of key importance in understanding the evolution of nanoparticles during sintering. During this process, two types of interfaces control the driving forces: the surface and the grain boundary. The knowledge of their energies is therefore of major importance to obtain reliable sintered bodies. The objective of this work was to present a quantitative relationship between the grain boundary energy and the surface energy of MgO and Ca-doped MgO nanoparticles to provide data to better understand the sintering behavior of this system, in particular delineating the thermodynamic basis of using Ca as sintering add. Using a novel and convenient calorimetric procedure, the ratio between the grain boundary energy and the surface energy was determined to be 1.1 for pure MgO and 0.7 for Ca-doped MgO. Based on these, the grain boundary energy of pure MgO and Ca-doped MgO were estimated to be 1.2 J.m-2 and 0.4 J.m-2, respectively. The grain boundary energy decrease caused by calcium doping was attributed to its interface segregation and influenced the sintering behavior by changing the equilibrium dihedral angle in addition to diffusion parameters.

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