Measurement and PC-SAFT modeling of solid-liquid equilibrium of deep eutectic solvents of quaternary ammonium chlorides and carboxylic acids
authors Pontes, PVA; Crespo, EA; Martins, MAR; Silva, LP; Neves, CMSS; Maximo, GJ; Hubinger, MD; Batista, EAC; Pinho, SP; Coutinho, JAP; Sadowski, G; Held, C
nationality International
journal FLUID PHASE EQUILIBRIA
author keywords Melting properties; Thermodynamics; Tetra alkyl ammonium salts; Fatty acids; Phase diagrams
keywords DIRECTIONAL ATTRACTIVE FORCES; DIFFERENTIAL SCANNING CALORIMETRY; PERTURBED-CHAIN SAFT; EQUATION-OF-STATE; IONIC LIQUIDS; FATTY-ACIDS; PHASE-BEHAVIOR; ASSOCIATING FLUIDS; BINARY-MIXTURES; PALMITIC-ACID
abstract In this study the solid-liquid equilibria (SLE) of 15 binary mixtures composed of one of three different symmetrical quaternary ammonium chlorides and one of five different fatty acids were measured. The experimental data obtained showed extreme negative deviations to ideality causing large melting temperature depressions (up to 300 K) that are characteristic for deep eutectic systems. The experimental data revealed that cross-interactions between quaternary ammonium salt and fatty acid increase with increasing alkyl chain length of the quaternary ammonium chloride and with increasing chain length of the carboxylic acid. The pronounced decrease of melting temperatures in these deep eutectic systems is mainly caused by strong hydrogen-bonding interactions, and thermodynamic modeling required an approach that takes hydrogen bonding into account. Thus, the measured phase diagrams were modeled with perturbed-chain statistical associating fluid theory based on the classical molecular homonuclear approach. The model showed very good agreement with the experimental data using a semi-predictive modeling approach, in which binary interaction parameters between quaternary ammonium chloride and carboxylic acid correlated with chain length of the components. This supports the experimental findings on the phase behavior and interactions present in these systems and it allows estimating eutectic points of such highly non-ideal mixtures. (C) 2017 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0378-3812
isbn 1879-0224
year published 2017
volume 448
beginning page 69
ending page 80
digital object identifier (doi) 10.1016/j.fluid.2017.04.007
web of science category Thermodynamics; Chemistry, Physical; Engineering, Chemical
subject category Thermodynamics; Chemistry; Engineering
unique article identifier WOS:000405767200010

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