Experimental measurement of the hygroscopic grade on eight imidazolium based ionic liquids

Cuadrado, S.; Domı́nguez-Pérez, Montserrat; Rilo, Esther; Garcı́a-Garabal, Sandra; Segade, Luisa; Franjo, C.; Cabeza, O.

doi:10.1016/j.fluid.2008.12.008

Cited by 103 publications

(119 citation statements)

References 7 publications

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“…It is well-known that the presence of water in ILs is almost inevitable due to their highly hygroscopic character [22,23]. This fact can have a profound impact on their properties and the applications of these solvents.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid–water mixtures

Docampo‐Álvarez

Gómez-González

Montes‐Campos

et al. 2016

J. Phys.: Condens. Matter

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Abstract.This work describes the behaviour of water molecules in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid under nanoconfinement between graphene sheets. By means of molecular dynamics simulations, an adsorption of water molecules at the graphene surface is studied. A depletion of water molecules in the vicinity of the neutral and negatively charged graphene surfaces and their adsorption at the positively charged surface are observed in line with the preferential hydration of the ionic liquid anions. The findings are appropriately described using a two-level statistical model. The confinement effect on the structure and dynamics of the mixtures is thoroughly analyzed using the density and the potential of mean force profiles, as well as by the vibrational densities of states of water molecules near the graphene surface. The orientation of water molecules and the water-induced structural transitions in the layer closest to the graphene surface are also discussed.

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Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid–water mixtures

Docampo‐Álvarez

Gómez-González

Montes‐Campos

et al. 2016

J. Phys.: Condens. Matter

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“…12,34 Previous studies were performed on bulk quantities of ILs. However, there are kinetic limitations associated with studying large quantities of ILs, often taking several hours or longer for bulk ILs to reach equilibrium with water vapor.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Work by Cuadrado-Prado et al studied the change in mass of 1 mL volumes (initial masses: ∼1−2 g) of imidazolium-based ILs with [BF 4 − ] and alkyl sulfate anions after exposure to varying levels of relative humidity (RH). 34 They found that the mass of IL film increased as the RH increased, though it was incorrectly concluded that water was only adsorbed on the surface, creating a thin film. At 100% RH, it took from 80 to 100 h for the ILs to reach an equilibrium with the atmospheric water vapor and become completely saturated (without stirring).…”

Section: ■ Introductionmentioning

confidence: 99%

Interaction of Water Vapor with the Surfaces of Imidazolium-Based Ionic Liquid Nanoparticles and Thin Films

et al. 2012

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Understanding the interactions of humid air with ionic liquids (ILs) is critical for predicting how their physicochemical properties are affected by water. Using experimental and theoretical techniques, water vapor's interaction with aerosolized nanoparticles and thin films of [C 2 MIM][Cl] and [C 2 MIM][BF 4 ] was studied. Solutions were electrosprayed to produce dry particles. Particles' hygroscopic growth was quantified using tandem nanodifferential mobility analysis as a function of relative humidity (RH). This is the first report of the interaction of water with aerosolized IL nanoparticles. The particles' small size allows true IL−water vapor equilibrium achieved quickly. Growth curves for both ILs show steady water uptake with increasing RH. Water vapor uptake by IL thin films was also examined using ATR-FTIR spectroscopy. . They represent a large class of molecules that have unique and widely tunable physical and chemical properties. 1−3 For example, there is a significant interest in the use of ILs in green chemistry, 2,4,5 due to their negligible vapor pressure at room temperature, 6 and for many other applications including solvents in synthesis and catalysis, 1,6 chemical extraction, 1,2,5 and fuel cells. 7 Physical properties such as conductivity, viscosity, density, and surface tension of ILs are known to depend on the presence of water, both adsorbed and absorbed. 3,8 Water is ubiquitous in the environment, and hygroscopic ILs such as those with imidazolium-based cations can uptake significant amounts of water vapor from ambient air, which alters their physical and chemical properties. 1,3 Thus, quantification of water uptake by hygroscopic ILs and understanding how the presence of water affects the nature of the ion−ion and ion−water interactions are critical for use of ILs in future applications. 8−14 Numerous experimental and theoretical studies have investigated the interaction of imidazolium-based ILs with water. 3,8−35 It is understood that both the cation and the anion have an effect on how ILs interact with water, with the anion having a stronger effect. 3,17,19 Early experimental work by Seddon et al. investigated the miscibility of water with ILs containing 1-nalkyl-3-methylimidazolium ([C n MIM + ], n = number of carbons on the linear alkyl chain) cations and various anions at room temperature. 3 It was determined that, regardless of the alkyl chain length, all halide anions were fully soluble in water and all hexafluorophosphate ([PF 6 − ]) anions were insoluble. 3 However, alkyl chain length did have an effect on water miscibility of [C n MIM + ]-based ILs with tetrafluoroborate ([BF 4 − ]) anions; for chain lengths of n = 2 or 4, the ILs were fully miscible, but for n > 4, the ILs formed biphasic systems. 3 Cammarata et al. performed early attenuated total reflection (ATR) infrared (IR) studies on the molecular states of water

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“…This absorbed water interacts with the anions of the ILs, and these interactions lead to changes in the structure of the absorbed water. More recently, another quantitative evaluation of the amount of water present in ILs has been reported [3]. In this contribution, measurements of the variation of mass suffered by eight different ionic liquids (ILs) of the 1-alkyl-3-methyl imidazolium tetrafluoroborate (CnMIM-BF4) and 1-ethyl-3-methyl imidazolium alkyl sulfate (EMIM-C n S) families, according to the atmosphere humidity grade were done.…”

Section: Introductionmentioning

confidence: 99%

Theoretical model for moisture adsorption on ionic liquids: A modified Brunauer–Emmet–Teller isotherm approach

Carrete¹,

García²,

Rodríguez³

et al. 2011

Fluid Phase Equilibria

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Experimental measurement of the hygroscopic grade on eight imidazolium based ionic liquids

Cited by 103 publications

References 7 publications

Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid–water mixtures

Molecular dynamics simulation of the behaviour of water in nano-confined ionic liquid–water mixtures

Interaction of Water Vapor with the Surfaces of Imidazolium-Based Ionic Liquid Nanoparticles and Thin Films

Theoretical model for moisture adsorption on ionic liquids: A modified Brunauer–Emmet–Teller isotherm approach

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