Freezing Point Determination of Water–Ionic Liquid Mixtures

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Freezing points ofaqueous solutions of HOEtpyBr, HOEtmimBr, AmimCl,EtOMmimCl, EmimDep, and EmimAc were measured using a modified Beckmannapparatus with automatic data logging. The ionic liquids (ILs) inthis study exhibited features similar to those of inorganic saltsin depressing the freezing point of water. On the basis of the cryoscopicbehavior recorded, the solid phases formed at higher IL contents werepresumed to be hydrates of the form IL·nH2O. The HOEtpyBr+H2O and HOEtmimBr+H2O systems formed simple eutectic systems. The eutectic points werefound to be at a water mole fraction of 0.617 and 219.841 K in thefirst system and at a water mole fraction of 0.657 and 202.565 K inthe second system. Water activities in aqueous IL solutions were predictedby COSMO-RS and COSMO-SAC and compared to water activities derivedfrom the experimentally determined freezing points. The COSMO-RS predictionswere closer to the experimental water activities than the COSMO-SACpredictions. The experimental results indicate that the freezing pointsof IL+H2O systems are affected by the nature of both cationsand anions. However, according to the COSMO-RS excess enthalpy predictionresults, the anions have a relatively higher influence than cationson the IL+H2O interaction.
Original languageEnglish
JournalJournal of Chemical and Engineering Data
Issue number8
Pages (from-to)2374–2383
Publication statusPublished - 2017
CitationsWeb of Science® Times Cited: No match on DOI
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ID: 134489241