Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/68795
Type: Artigo
Title: On the solid-liquid equilibrium of binary mixtures of fatty alcohols and fatty acids
Author: Maximo, G. J.
Carareto, N. D. D.
Costa, M. C.
dos Santos, A. O.
Cardoso, L. P.
Krahenbahl, M. A.
Meirelles, A. J. A.
Abstract: Fatty alcohols and fatty acids are used in the cosmetic, pharmaceutical and food industries as surfactants. They are also considered phase change materials for thermal storage processes. Information on their thermal properties is required for optimizing production processes as well as for improving their industrial and home use. In the present study, the solid-liquid phase diagrams of three binary systems of 1-tetradecanol + dodecanoic acid, 1-hexadecanol + tetradecanoic acid and 1-octadecanol + hexadecanoic acid were determined by differential scanning calorimetry. The phase-transition phenomena were further investigated by optical micrographs and X-ray diffraction patterns. The experimental data showed that the systems present eutectic transitions and some of them exhibit partial solid phase miscibility. The liquid phase activity coefficients were calculated by Margules 2 and 3-suffix and by UNIFAC and UNIFAC-Dortmund methods. The modeling approach resulted in an accurate prediction, with average absolute deviations from experimental data lower than 1.16 K. The values of excess Gibbs free energy present an unusual behavior, with positive deviations at very low alcohol concentrations and negative ones at high concentrations of this component. This occurs due to changes in the H-bonding interactions along the concentration range of the mixture. (C) 2014 Elsevier B.V. All rights reserved.
Fatty alcohols and fatty acids are used in the cosmetic, pharmaceutical and food industries as surfactants. They are also considered phase change materials for thermal storage processes. Information on their thermal properties is required for optimizing production processes as well as for improving their industrial and home use. In the present study, the solid-liquid phase diagrams of three binary systems of 1-tetradecanol + dodecanoic acid, 1-hexadecanol + tetradecanoic acid and 1-octadecanol + hexadecanoic acid were determined by differential scanning calorimetry. The phase-transition phenomena were further investigated by optical micrographs and X-ray diffraction patterns. The experimental data showed that the systems present eutectic transitions and some of them exhibit partial solid phase miscibility. The liquid phase activity coefficients were calculated by Margules 2 and 3-suffix and by UNIFAC and UNIFAC-Dortmund methods. The modeling approach resulted in an accurate prediction, with average absolute deviations from experimental data lower than 1.16 K. The values of excess Gibbs free energy present an unusual behavior, with positive deviations at very low alcohol concentrations and negative ones at high concentrations of this component. This occurs due to changes in the H-bonding interactions along the concentration range of the mixture.
Subject: Equilíbrio sólido-liquido
Varredura diferencial de calorimetria
Raios - Difração
Modelagem termodinâmica
Country: Holanda
Editor: Elsevier
Citation: Fluid Phase Equilibria. Elsevier Science Bv, v. 366, n. 88, n. 98, 2014.
Rights: fechado
Identifier DOI: 10.1016/j.fluid.2014.01.004
Address: https://www.sciencedirect.com/science/article/pii/S0378381214000193
Date Issue: 2014
Appears in Collections:IFGW - Artigos e Outros Documentos
FEA - Artigos e Outros Documentos
FEQ - Artigos e Outros Documentos

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