Viscosity Of Ionic Liquids Research Articles

Reversible Carbon Dioxide Capture at High Temperatures by Tetraethylenepentamine Acetic Acid and Polyethylene Glycol Mixtures with High Capacity and Low Viscosity

Ionic liquids (ILs) are investigated in many studies to capture CO2 in recent years. However, almost all of these studies carried out the absorption of CO2 by ILs at relatively low temperatures (lower than 333.15 K or even around room temperature). Besides, the viscosity of ILs increases dramatically after absorbing CO2, which could reduce the absorption efficiency significantly. Reversible and efficient absorption of CO2 at high temperatures was investigated by IL of tetraethylenepentamine acetic acid ([TEPA]Ac) and polyethylene glycol 200 (PEG-200) mixtures with low viscosity. The results showed that the absorption capacity of [TEPA]Ac/PEG-200 mixtures achieved 1.24 mol of CO2/mol of [TEPA]Ac at 353.15 K at ambient pressure (1.01 bar). The mixtures could be easily regenerated by bubbling dried N2 through them. The addition of PEG-200 in [TEPA]Ac could increase the efficiency of absorption and desorption significantly. Furthermore, the solubility data of CO2 in the [TEPA]Ac/PEG-200 mixtures at T = 353.15...

Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors.

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th , 2014. The dataset consists of 4,329 measurements taken from 165 ILs made up of 72 cations and 34 anions. We benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset.

Electrical, optical and electrophotochemical studies on agarose based biopolymer electrolyte towards dye sensitized solar cell application

Abstract This paper reports the latest work in our laboratory on biopolymer electrolyte for dye sensitized solar cell (DSSC) application. Biopolymer electrolyte comprises agarose, potassium iodide (KI) were dissolved in two different solvents dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). To further achieve the reasonable conductivity for DSSC application we have added a low viscosity ionic liquid (IL) in the biopolymer electrolytes. The room temperature conductivity maximum was obtained near 60:40 compositions. Structural, electrical and photo electrochemical studies have been carried out in details and explained. These electrolytes were further used in the fabrication of DSSC, and comparative measured values of the fill factor (FF), Open circuit voltage (Voc), current density (Jsc) and efficiency at 100 mW/cm were tabulated. The results obtained from data evaluation affirm that biopolymer – IL gel electrolytes appears promising candidates for energy devices.

Microviscosity Offered by Ionic Liquids and Ionic Liquid-Glycol Mixtures Is Probe Dependent.

Interactions present within the solubilizing media constituted of ionic liquids (ILs) govern the outcomes of chemical processes carried out within such media by controlling the behavior of solutes dissolved therein. Fluidity afforded by IL-based media, in this context, not only reveals interactions present within the system, but it also helps decide whether the system is suitable for an application. The response of spectroscopic microviscosity probes dissolved in IL and IL-based solvents, in this regard, reveals information on both solute-solvent and solvent-solvent interactions present within the system. Interactions present within the cybotactic region of a microviscosity probe strongly depend on the functionalities present on the probe. Five different fluorescence probes representing three different classes of microviscosity reporting systems based on intramolecular excimer formation, steady-state fluorescence anisotropy, and fluorescence intensity are used to explore fluidity afforded by 11 ILs and their equimolar mixtures with tetraethylene glycol (TEG), a solvent having the ability to readily hydrogen bond, under ambient conditions. ILs are categorized into four sets: first having the same cation and different anions to assess the role of the anion, second having the same anion and different cations to assess the role of the cation, and the last two having C2-H substituted imidazolium cations with different anions to reveal the role of C2-H, if any, in H-bonding interactions involving ILs. The responses of all of the microviscosity probes within ILs and (IL + TEG) equimolar mixtures are compared with the bulk dynamic viscosities of the corresponding systems. The overall investigation reveals the lack of a trend between the probe responses representing microviscosity and the dynamic viscosities of IL and (IL + TEG) mixtures. The cybotactic region viscosity of the (IL + TEG) equimolar mixture depends on the identity of the probe; it may be higher than, lower than, or in between the microviscosities reported in both neat IL and neat TEG. Evidence of the role of C2-H on the imidazolium cation in intraspecies (within IL) or interspecies (between IL and TEG) H-bonding was not found.

The Viscosity and Density of Ionic Liquid + Tetraglyme Mixtures and the Effect of Tetraglyme on CO2 Solubility

We show that the addition of tetraglyme (TG), which is a low viscosity liquid with relatively low vapor pressure, is effective in reducing the viscosity of ionic liquids (ILs). In particular, we measure the viscosities of mixtures of 18 ionic liquids with tetraglyme at temperatures between 278.15 and 323.15 K, with a focus on mixtures that are primarily ionic liquid. Thirteen of the ionic liquids contain aprotic heterocyclic anions (AHA ILs) paired with tetra-alkylphosphonium and imidazolium cations, which we have developed for cofluid vapor compression refrigeration and postcombustion CO2 capture applications. Three bis(trifluoromethylsulfonyl)amide ([Tf2N]−) ionic liquids are included for comparison, as well as trihexyltetradecylphosphonium acetate and trihexyltetradecylphosphonium dicyanamide ([P66614][acetate] and [P66614][DCA]). In addition, we present the densities of trihexyltetradecylphosphonium 1,2,3-triazolide ([P66614][3-Triz]) + tetraglyme mixtures at temperatures between 283.15 and 353.15 K. Finally, we show that the solubility of CO2 in mixtures of [P66614][3-Triz] + 30 mol % tetraglyme and trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][4-Triz]) + 30 mol % tetraglyme at 313.15, 333.5, and 353.6 K and pressures to 34 bar can be represented reasonably well by a mole fraction weighted sum of the solubilities (on a mole ratio basis) in the two pure components.

Viscosities and Conductivities of [BMIM]Zn(Ac)xCly(x=0,1,2,3; y=3,2,1,0) Ionic Liquids at Different Temperatures

Viscosity and conductivity data of BMIMZnAcxCly(x=0,1,2,3; y=3,2,1,0) ionic liquids were detected at temperature ranging from 323.15 to 353.15 K with an interval of 5 K. The conductivities of different ionic liquids at the same temperature followed the trend [BMIM][ZnAcCl2] > [BMIM][ZnAc2Cl] > [BMIM][ZnCl3] > [BMIM][ZnAc3]. The viscosities of different ionic liquid abided by the order [BMIM][ZnCl3] > [BMIM][ZnAcCl2] > [BMIM][ZnAc2Cl] > [BMIM][ZnAc3]. Acetate ion could reduce the viscosity of ionic liquids. The relationship between viscosity/conductivity and temperature obeyed the Arrhenius equation and Vogel-Fulcher-Tammann (VFT) equation very well with above 0.99 correlation coefficients.

Effects of electrostatic interaction on the properties of ionic liquids correlated with the change of free volume.

In this study, the amount of free volume in ionic liquids (ILs) was calculated and found to be almost half to that of their isoelectronic neutral analogues. MD simulations revealed that the significantly compressed free volume in the ILs was dominantly attributed to the strong inter-ion electrostatic interactions, which are comparable to the application of an external pressure of ∼250 MPa to the neutral analogues. Furthermore, the change in the free volume shows an interconnection with other properties of ILs, especially viscosity. The inherent high viscosity of ILs was quantitatively correlated to a low free volume available for mass transfer, and the sharp decrease in the viscosity of ILs with the addition of organic solvents was essentially caused by the introduction of free volume.

镁基类离子液体制备及物化性质的测定

以氯化胆碱和六水氯化镁为原料，采用自组装反应直接合成镁基类离子液体。对合成的类离子液体的粘度、电导率、密度和组成的变化关系进行了分析。结果表明合成的温度和组成是影响类离子液体物化性能的关键因素。随着温度和组成的变化，镁基类离子液体的粘度、电导率、密度均发生显著的变化。 With choline chloride magnesium chloride hydrate as raw material, magnesium ion liquid was synthesized by self-assembly reaction. The viscosity, conductivity, density and composition of the ionic liquids were analyzed. The results show that the temperature and composition were the key factors affecting the physicochemical properties of the ionic liquids. With the change of temperature and composition, the viscosity, conductivity and density of magnesium ionic liquids were changed significantly.

Temperature effects on the viscosity and the wavelength-dependent refractive index of imidazolium-based ionic liquids with a phosphorus-containing anion

A systematic study on the viscosity and refractive index of 1-alkyl-3-methylimidazolium based ionic liquids (alkyl = methyl, butyl and hexyl) combined with three phosphorus containing anions, i.e. dimethylphosphate, methyl methylphosphonate and methylphosphonate, is reported. Experimental measurements account for temperature effects, while the refractive index is determined at multiple wavelengths in the visible and near infrared region. Despite the structural similarity of these anions, significant differences in the physical properties of the resulting ILs are identified, along with the clear trend of viscosity increase - and refractive index decrease - with increasing alkyl chain length on the cation. Ab initio theoretical calculations are carried out to support and rationalise the observed behaviour.

Carbon Dioxide Capture with Ionic Liquids and Deep Eutectic Solvents: A New Generation of Sorbents.

High cost and high energy penalty for CO2 uptake from flue gases are important obstacles in large-scale industrial applications, and developing efficient technology for CO2 capture from technical and economic points is crucial. Ionic liquids (ILs) show the potential for CO2 separation owing to their inherent advantages, and have been proposed as alternatives to overcome the drawbacks of conventional sorbents. Chemical modification of ILs to improve their performance in CO2 absorption has received more attention. Deep eutectic solvents (DESs) as a new generation of ILs are considered as more economical alternatives to cope with the deficiencies of high cost and high viscosity of conventional ILs. This Review discusses the potential of functionalized ILs and DESs as CO2 sorbents. Incorporation of CO2 -philic functional groups, such as amine, in cation and/or anion moiety of ILs can promot their absorption capacity. In general, the functionalization of the anion part of ILs is more effective than the cation part. DESs represent favorable solvent properties and are capable of capturing CO2 , but the research work is scarce and undeveloped compared to the studies conducted on ILs. It is possible to develop novel DESs with promising absorption capacity. However, more investigation needs to be carried out on the mechanism of CO2 sorption of DESs to clarify how these novel sorbents can be adjusted and fine-tuned to be best tailored as optimized media for CO2 capture.

Estimation of viscosities of pure ionic liquids using an artificial neural network based on only structural characteristics

In this work, a three layer feed-forward artificial neural network, with 24 neurons, was constructed to estimate the viscosities of a wide range of ionic liquid families, including those based on the imidazolium, ammonium, pyridinium, pyrrolidinium, phosphonium, and isoquinolinium cations, together with various anions, as well as varying lengths of alkyl side-chain lengths. The model is a function of the molecular weight and structure of the ionic liquid, and the system conditions of temperature and pressure. It covers a temperature range of (273.15 to 393.15) K and a pressure range of (0.1 to 150) MPa. Results indicated the estimated values of viscosities of pure ionic liquids to be in good agreement with the experimental data. The training (correlating) and validation coefficients (R) were 1.00000 and 0.99955, respectively, while the training and validation performances (MSE) on the training and validation datasets were 4.36×10−8, and 1.63×10−6, respectively. The average absolute error value on the test dataset was 1.310%.

Viscosity and self-diffusivity of ionic liquids with compressed hydrofluorocarbons: 1-Hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide and 1,1,1,2-tetrafluoroethane

The viscosity and self-diffusivity of mixtures of the ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([HMIm][Tf2N]), and the compressed gas, 1,1,1,2-tetrafluoroethane (R-134a), were measured at three different temperatures (298.15 K, 323.15 K, 343.15 K) and pressures to 21 bar. The high-pressure vapor-liquid equilibrium (VLE) of the ionic liquids with R-134a was measured to calculate the composition of the liquid phase at the various pressures encountered in the viscosity and diffusivity measurements. The viscosity of the ionic liquid decreases significantly with increased composition of R-134a at VLE. The “excess” viscosity demonstrates positive values that are believed to represent relatively strong intermolecular forces of the polar R-134a and [HMIm][Tf2N]. The self-diffusivity of mixtures of [HMIm][Tf2N] and liquefied R-134a (298.15 K and 6.7 bar) was measured and increases significantly with increases in the composition of R-134a. The self-diffusivity of [HMIm][Tf2N] in vapor-liquid equilibrium with compressed R-134a gas was measured and indicates similar increases in diffusivity with composition of R-134a. The diffusivity demonstrates close Stokes-Einstein behavior using the measured mixture viscosity data and ambient pressure self-diffusivity.

Detonation Nanodiamond as a New Option for Reduction of the Viscosity of one Novel Di–azide Functionalized Monocationic Ionic Liquid

AbstractA novel di‐azide functionalized monocationic ionic liquid (IL) based on the dicyanamide anion were synthesized and characterized. Reduced graphene oxide (r‐GO) and detonation nanodiamond (DND) were synthesized according Hummer′s method and explosion of the mixture of 60 wt% TNT (2,4,6‐trinitrotoluene) and 40 wt% RDX (1,3,5‐trinitroperhydro‐1,3,5‐triazine) respectively. Dispersions of DND, r‐GO and graphite (Gr) powder in the synthesized IL were successfully achieved with sonication at 80 °C. The viscosity as well as thermal behavior of these dispersions was investigated and compared with neat IL. The experimental results showed that particles, especially DND, added to the synthesized IL exhibit good viscosity‐reduction. So that, concentration of 0.08 % (w/w) of DND decreases the viscosity up to 63.33 cP at 25 °C, as compared to neat IL. The addition of DND with 0.08 % w/w to other ILs showed that this nanoparticle leads to decrease of the viscosity of these Ils. In addition, all of the particles caused to increase the thermal decomposition temperature of synthesized IL and there is no noticeable difference between them. In fact, this work offers DND as a new option for reduction of viscosity of ILs.

Development of facilitated transport membranes with low viscosity aprotic heterocyclic anion type ionic liquid as a CO2 carrier

ABSTRACTLow viscosity ionic liquids (ILs) composed of a cation with methoxy group and an aprotic heterocyclic anion (AHA) with highly nucleophilic amino group were synthesized and examined as a CO2 carrier of facilitated transport membranes. Due to the low viscosity of the AHA-type ILs after CO2 absorption, the AHA-type IL-based membrane showed high CO2 permeability (ca. 3900 barrer) with 200 of CO2/CH4 selectivity under dry condition at 323 K, which was much higher than that of amino acid ILs-based membrane (ca. 150 barrer with ca. 50 of CO2/CH4 selectivity).

New Method Based on the UNIFAC–VISCO Model for the Estimation of Ionic Liquids Viscosity Using the Experimental Data Recommended by Mathematical Gnostics

The viscosity of ionic liquids (ILs) has been modeled as a function of temperature and at atmospheric pressure using a new method based on the UNIFAC–VISCO method. This model extends the calculations previously reported by our group (see Zhao et al. J. Chem. Eng. Data 2016, 61, 2160–2169) which used 154 experimental viscosity data points of 25 ionic liquids for regression of a set of binary interaction parameters and ion Vogel–Fulcher–Tammann (VFT) parameters. Discrepancies in the experimental data of the same IL affect the quality of the correlation and thus the development of the predictive method. In this work, mathematical gnostics was used to analyze the experimental data from different sources and recommend one set of reliable data for each IL. These recommended data (totally 819 data points) for 70 ILs were correlated using this model to obtain an extended set of binary interaction parameters and ion VFT parameters, with a regression accuracy of 1.4%. In addition, 966 experimental viscosity data po...

Modification of gas selective SAPO zeolites using imidazolium ionic liquid to develop polysulfone mixed matrix membrane for CO2 gas separation

Ionic liquids (ILs) with high CO2 solubility and selectivity have been extensively studied in recent years to improve the performance of CO2 separation membranes. The progress in the development of supported IL membranes, polymerized IL membrane, polymer/IL gel membranes and membrane gas absorption using IL is limited by the high viscosity and price of ILs. In this work, the gas selective SAPO-34 zeolite was modified using [emim][TF2N] IL before the zeolites were incorporated into polysulfone (PSf) asymmetric membrane which was prepared by phase inversion. The main objective of this work is to study the effects of immersion duration on the IL-functionality of zeolite, membrane morphology and gas separation properties of PSf/SAPO-34 zeolite mixed matrix membrane. The incorporation of IL into the SAPO zeolite was confirmed by energy dispersive X-ray analysis. This analysis also proved the well dispersion of SAPO-34 particles with IL modification for 6 h due to the improved polymer/filler interface morphology as shown by scanning electron microscopy analysis. The gas separation test further revealed that the membrane containing SAPO-34 modified with IL for 6 h showed a great enhancement in both CO2/CH4 and CO2/N2 selectivity (approximately 486% and 232% respectively) over the unmodified mixed matrix membrane.

NIR hyperspectral investigation of extraction kinetics of ionic-liquid assisted bitumen extraction

The use of room temperature ionic liquids (IL) to assist bitumen extraction from oil sands in a waterless process was investigated. Four ILs were selected according to their ability to meet industrial requirements. Their impact on bitumen recovery and bitumen quality (fines content) was assessed through a mixed-level experimental design accounting for temperature, contact time, solvent-to-oil sands ratio, IL-to-oil sands ratio, water-to-IL ratio, solvent and IL types. In parallel, an innovative through-flow microcell coupled to near infrared spectroscopy (NIR) was developed to monitor on-line the IL-assisted bitumen extraction kinetics along with a quantitative reconstruction strategy using projection to latent structure (PLS) method. The choice of solvent rather than IL was the main impacting factor on bitumen recovery while the NIR extraction kinetic tests revealed that IL viscosity drastically reduced the rate constant of bitumen recovery. However, ILs were significant in capturing fines from bitumen with [EtNH3][NO3] as the best candidate.

Density, refractive index and kinematic viscosity of MIPK, MEK and phosphonium-based ionic liquids and the excess and deviation properties of their binary systems

The density, refractive index, and kinematic viscosity were measured for extraction solvents for molybdenum: methyl ethyl ketone (MEK), methyl isopropyl ketone (MIPK), trihexyl tetradecyl phosphonium chloride ([P666,14] [Cl]), trihexyl tetradecyl phosphonium dicyanamide ([P666,14][DCA]) and trihexyl tetradecyl phosphonium bis (2,2,4- trimethyl pentyl) phosphinate ([P666,14][TMPP]) at atmospheric pressure for a temperature range of 288.15-318.15 K. The experimental data were correlated using the Daubert and Danner equation, a linear equation and the Goletz and Tassion equation. In addition, the excess molar volumes (VE) and the deviations in molar refractivity (ΔR) at 298.15 K were reported for the following binary systems: {MEK+[P666,14][Cl]}, {MEK+[P666,14][DCA]}, {MEK+[P666,14][TMPP]}, {MIPK+[P666,14][Cl]}, {MIPK+[P666,14][DCA]} and {MIPK+[P666,14][TMPP]}. The determined VE and ΔR values were correlated with the Redlich-Kister equation. The binary density and refractive index data at 298.15 K were also predicted using several mixing rules, and these results were then compared with the experimental data.

Measurement of high pressure densities and atmospheric pressure viscosities of alkyl phosphate anion ionic liquids and correlation with the ε∗-modified Sanchez-Lacombe equation of state

High pressure densities up to 200MPa from 313 to 393K and atmospheric pressure viscosities from 293 to 373K for two alkyl phosphate anion ionic liquids, 1-ethyl-3-methylimidazolium dimethylphosphate ([emim][DMP]) and 1-butyl-3-methylimidazolium dimethylphosphate ([bmim][DMP]), are reported. Several forms of the Tait equation were applied and all forms could correlate the data to within 0.03% average relative deviation (ARD). The derivative properties calculated had specific trends for the ionic liquids. The ε∗-modified Sanchez-Lacombe equation of state could correlate the data to within an ARD of 0.07%, and the deviations were lower than those of the original Sanchez-Lacombe equation of state (0.19%). The improvement by ε∗-modified Sanchez-Lacombe equation of state can be attributed its assumed close-packed density structure at low temperature.

Separate density and viscosity measurements of unknown liquid using quartz crystal microbalance

Aqueous liquids have a wide range of applications in many fields. Basic physical properties like the density and the viscosity have great impacts on the functionalities of a given ionic liquid. For the millions kinds of existing liquids, only a few have been systematically measured with the density and the viscosity using traditional methods. However, these methods are limited to measure the density and the viscosity of an ionic liquid simultaneously especially in processing micro sample volumes. To meet this challenge, we present a new theoretical model and a novel method to separate density and viscosity measurements with single quartz crystal microbalance (QCM) in this work. The agreement of experimental results and theocratical calculations shows that the QCM is capable to measure the density and the viscosity of ionic liquids.