resumo
The vapor liquid-equilibrium of water + ionic liquids is relevant for a wide range of applications of these compounds. It is usually measured by ebulliometric techniques, but these are time consuming and expensive. In this work it is shown that the activity coefficients of water in a series of cholinium-based ionic liquids can be reliably and quickly estimated at 298.15K using a humidity meter instrument. The cholinium based ionic liquids were chosen to test this experimental methodology since data for water activities of quaternary ammonium salts are available in the literature allowing the validation of the proposed technique. The COSMO-RS method provides a reliable description of the data and was also used to understand the molecular interactions occurring on these binary systems. The estimated excess enthalpies indicate that hydrogen bonding between water and ionic liquid anion is the dominant interaction that governs the behavior of water and cholinium-based ionic liquids systems, while the electrostatic-misfit and van der Walls forces have a minor contribution to the total excess enthalpies. The results here reported show that water activity measurements allow a quick scan for selecting ionic liquids according to their behavior in mixtures with water. (C) 2013 Elsevier B.V. All rights reserved.
palavras-chave
AQUEOUS 2-PHASE SYSTEMS; BINARY-SYSTEMS; THERMODYNAMIC PROPERTIES; INFINITE DILUTION; EXCESS-ENTHALPIES; PLUS ETHANOL; CHLORIDE; ELECTRODEPOSITION; EQUILIBRIA; SOLVENTS
categoria
Thermodynamics; Chemistry; Engineering
autores
Khan, I; Kurnia, KA; Sintra, TE; Saraiva, JA; Pinho, SP; Coutinho, JAP
nossos autores
Imran Khan
Bolseiro de pós-Doutoramento
Kiki Adi Kurnia
Bolseiro de pós-Doutoramento
Tânia Ereira Sintra
Bolseiro de pós-DoutoramentoGrupos
G4 - Materiais Renováveis e Economia Circular
G6 - Materiais Virtuais e Inteligência Artificial
agradecimentos
This work was financed by national funding from Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the CICECO (project Pest-C/CTM/LA0011/2013), QOPNA (project Pest-C/QUI/UI0062/2011) and LSRE/LCM (project Pest-C/EQB/LA0020/2013). Imran Khan and Kiki A. Kurnia acknowledge FCT for the postdoctoral grants SFRH/BPD/76850/2011 and SFRH/BPD/88101/2012, respectively and also Tania E. Sintra acknowledge FCT doctoral grant SFRH/BD/85871/2012.