Navegando por Autor "Gmehling, Jürgen"
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Artigo Activity coefficient at infinite dilution measurements for organic solutes (polar and non-polar) in fatty compounds – Part II: C18 fatty acids(Elsevier, 2013-05) Chiavone Filho, Osvaldo; Belting, Patrícia Castro; Rarey, Jürgen; Gmehling, Jürgen; Ceriani, Roberta; Meirelles, Antonio José de AlmeidaIn this work, activity coefficients at infinite dilution (c113) have been measured for 21 solutes (subscript 1) (alkanes, cycloalkanes, alkenes, aromatic compounds, alcohols, esters, ketones, and halogenated hydro carbons), in four solvents (subscript 3), namely one saturated fatty acid and three unsaturated fatty acids: stearic (octadecanoic) acid – C18:0, oleic (cis-9-octadecenoic) acid – C18:1 9c, linoleic (cis,cis-9,12- octadecadienoic) acid – C18:2 9c12c, and linolenic (cis,cis,cis-9,12,15-octadecatrienoic) acid – C18:3 9c12c15c, by gas–liquid chromatography. The measurements were carried out at temperatures from (303.13 to 368.19) K and the partial molar excess Gibbs free energy (DGE;11 ), enthalpy (DHE;11 ), and entropy (DSE;11 ), at infinite dilution were calculated from experimental c113 values obtained over the tem- perature range. The uncertainties in determination of c113 and DHE;11 are 4% and 20%, respectively. The results for stearic acid obtained in this study have been compared to those available in the Dortmund Data Bank (DDB). The real behaviour of fatty systems could be better understood through the results obtained in this workArtigo Activity coefficient at infinite dilution measurements for organic solutes (polar and non-polar) in fatty compounds: Saturated fatty acids(Elsevier, 2012-12) Chiavone Filho, Osvaldo; Belting, Patrícia Castro; Rarey, Jürgen; Gmehling, Jürgen; Ceriani, Roberta; Meirelles, Antonio José de AlmeidaThe activity coefficients at infinite dilution , c113 (the subscript 1 and 3 correspond to solute and solvent, respectively), for 21 solutes, including alkane, cycloalkane, alkene, aromatic compounds, alcohol, ester, ketone, and halogenated hydrocarbons, in four solvents, that are the saturated fatty acids: capric (decanoic) acid, lauric (dodecanoic) acid, myristic (tetradecanoic) acid, and palmitic (hexadecanoic) acid, were determined by gas–liquid chromatography at temperatures from 314.10 K to 358.33 K. Comparison with previously published for selected solutes in palmitic (hexadecanoic) acid were also performed. The values of the partial molar excess Gibbs free energy, DG113, enthalpy, DH113, and entropy, DS113, at infinite dilution were calculated from experimental c113 values obtained over the temperature range. Results obtained in this work allow a more accurate description of the real behavior of fatty systemsArtigo Measurement, correlation and prediction of isothermal vapor–liquid equilibria of different systems containing vegetable oils(Elsevier, 2015-06-15) Chiavone Filho, Osvaldo; Belting, Patrícia Castro; Gmehling, Jürgen; Bölts, Rainer; Rarey, Jürgen; Ceriani, Roberta; Meirelles, Antonio José de AlmeidaThermodynamic properties, in particular vapor–liquid equilibrium (VLE) data, are required for the development of reliable predictive models for systems with fatty compounds. Isothermal VLE data have been measured for mixtures of methanol, ethanol, or n-hexane with refined vegetable oils (soybean, sunflower and rapeseed) at 348.15 K and 373.15 K using a computer-driven static apparatus. The oils were characterized in terms of their fatty acid and corresponding triacylglycerol (TAG) compositions. For the mixtures containing vegetable oils and n-hexane a negative deviation from Raoult’s law was observed and a homogeneous behavior (no miscibility gap) was found, while the mixtures with alcohols exhibited positive deviation from ideal behavior and, in some cases, limited miscibility. On the basis of the composition of the studied vegetable oils, their relative van der Waals volume and surface area parameters were estimated by the Bondi method and their vapor pressure by a group contribution method developed by Ceriani and Meirelles [1]. The experimental VLE data were correlated together with available excess enthalpies (HE) and activity coefficients at infinite dilution (gi1) data using the UNIQUAC model. For the fitting process the refined vegetable oil was treated as a single triacylglycerol (pseudo-component) which has the corresponding degree of unsaturation, number of carbon atoms and molar mass of the original oil composition. The overall-average errors (AAE) using UNIQUAC model are 4.46% for VLE, 7.07% for gi1 and 5.80% for HE The experimental data were also compared with the predicted results using mod. UNIFAC (Dortmund) and an extension of this method proposed for triacylglycerols in a previous work was also testedArtigo Measurements of activity coefficients at infinite dilution in vegetableoils and capric acid using the dilutor technique(Elsevier, 2014-01-15) Chiavone Filho, Osvaldo; Beltinga, Patrícia Castro; Rarey, Jürgen; Gmehling, Jürgen; Ceriani, Roberta; Meirelles, Antonio José de AlmeidaThis paper reports experimental activity coefficients at infinite dilution, , for methanol, ethanol and n-hexane in three refined vegetable oils (soybean, sunflower, and rapeseed oils) measured using the dilutor technique (inert gas stripping method). The measurements were carried out in the temperature range between 313.15 and 353.15 K. Furthermore, activity coefficients at infinite dilution for various solutes (acetone, methanol, ethanol, n-hexane, cyclohexane and toluene) were measured in capric (decanoic) acid using the same technique in the temperature range from 313.13 to 353.30 K. The new data obtained for capric acid and soybean oil were compared with already published experimental data. Additionally, densities of the investigated vegetable oils were measured in the temperature range from 293.15 to 353.15 K. Using the experimental values obtained over the temperature range, the partial molar excess Gibbs energy , enthalpy and entropy at infinite dilution were determined. The relative error for the measurements carried out using the dilutor technique is approximately ±2.5%. The measured data in the investigated refined vegetable oils were also compared with the results of the group contribution methods original UNIFAC and modified UNIFAC (Dortmund) and an extension of the latter method to triacylglycerols was proposed