Solution Thermodynamics of Imidazolium-Based Ionic Liquids and Water (original) (raw)
International Journal of Molecular Sciences, 2007
The salting-out effect produced by the addition of potassium phosphate, K 3 PO 4 to aqueous solutions of water-miscible ionic liquids, viz. 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, or 1-alkyl-3methylimidazolium chloride (alkyl = butyl, octyl or decyl) is investigated. The effects are analyzed using both the corresponding temperature-composition pseudo-binary and composition ternary phase diagrams. Different regions of liquid-liquid and solid-liquid phase demixing are mapped. The phase behavior is interpreted taking into account the complex and competing nature of the interactions between the ionic liquid, the inorganic salt and water. In the case of solutions containing 1-octyl-or 1-decyl-3-methylimidazolium chloride, the smaller magnitude of the salting-out effects is explained in terms of the possibility of self-aggregation of the ionic liquid.
Rapid Carbonation for Calcite from a Solid-Liquid-Gas System with an Imidazolium-Based Ionic Liquid
International Journal of Molecular Sciences, 2014
Aqueous carbonation of Ca(OH) 2 is a complex process that produces calcite with scalenohedral calcite phases and characterized by inadequate carbonate species for effective carbonation due to the poor dissolution of CO 2 in water. Consequently, we report a solid-liquid-gas carbonation system with an ionic liquid (IL), 1-butyl-3-methylimidazolium bromide, in view of enhancing the reaction of CO 2 with Ca(OH) 2 . The use of the IL increased the solubility of CO 2 in the aqueous environment and enhanced the transport of the reactive species (Ca 2+ and CO 3 2− ) and products. The presence of the IL also avoided the formation of the CaCO 3 protective and passivation layer and ensured high carbonation yields, as well as the production of stoichiometric rhombohedral calcite phases in a short time.
Phase Behavior at High Pressure of the Ternary System: CO2, Ionic Liquid and Disperse Dye
2012
High pressure phase behavior experimental data have been measured for the systems carbon dioxide (CO 2 ) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF 6 ]) and carbon dioxide (CO 2 ) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF 6 ]) + 1-amino-2-phenoxy-4-hydroxyanthraquinone (C.I. Disperse Red 60). Measurements were performed in the pressure up to 18 MPa and at the temperature (323 to 353 K). As reported in the literature, at higher concentrations of carbon dioxide the phase transition pressure increased very steeply. The experimental data for the binary and ternary systems were correlated with good agreement using the Peng-Robinson equation of state. The amount of water in phase behavior of the systems was evaluated.
Dalton transactions (Cambridge, England : 2003), 2014
RTILs as media to synthesize a variety of nanomaterials are gaining momentum owing to their unique physicochemical properties. However, the fundamental questions regarding the role of the inherent structure of the IL in directing the morphology and the growth mechanism of the nanoparticles are still unexplored. Therefore, an attempt was made in this respect wherein CdSe nanoparticles were synthesized in a neat room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium ethylsulfate ([EMIM][EtSO4]), under ambient conditions. The IL was found to play three roles, as a solvent, as a stabilizing agent and as a shape directing template. The primary nanoparticles were of the sizes in the range of 2-5 nm, as determined by HR-TEM. These primary nanoparticles grow into nanoflake-like units which further self-assemble and transform into a mixture of anisotropic nanostructures (predominantly 2D sheets and flower-like 3D patterns) as revealed by the SEM studies. The co-existence as well ...
RSC Advances, 2013
Chiral ionic liquids (CILs) tetrabutylammonium-(S)-prolinate, tetrabutylammonium-(R)-prolinate and tetrabutylammonium trans-4-hydroxy-(S)-prolinate were investigated as chiral additives in the Pdcatalyzed enantioselective hydrogenation of a,b-unsaturated ketones. These CILs were easily prepared in one step from the aminoacid and tetrabutylammonium hydroxide and characterized (NMR, IR, optical rotation, elemental analysis, DSC, viscosity, decomposition temperature). The research strategy was to assess the antimicrobial toxicity (>20 strains) and biodegradability (OECD 301D) of the CILs at the same time as undertaking the asymmetric catalysis study. The Pd-catalyzed enantioselective hydrogenation of the carbon-carbon double bond of a,b-unsaturated ketones under mild conditions (room temperature, 1 atm of H 2 ) in different solvents with CILs present. The best results were obtained in i-PrOH after 18 hours of reaction with a i-PrOH/IL ratio of 5. While all three CILs have low antimicrobial toxicity to a wide range of bacteria and fungi, tetrabutylammonium-(S)-prolinate, tetrabutylammonium-(R)-prolinate and tetrabutylammonium trans-4-hydroxy-(S)-prolinate did not pass the Closed Bottle biodegradation test.
Solvent Extraction and Ion Exchange, 2011
The extraction of U(VI) by tributylphosphate in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide), C 4 -mimTf 2 N, has been studied as a function of TBP and HNO 3 initial concentrations. Extraction 10 measurements have been completed by UV-vis spectroscopy in order to get insights into the extraction mechanism. The proposed chemical model describes the data through a fit of the uranyl extraction coefficient, while some other suggestions are unable to do so. In this model, uranyl extraction is proposed to proceed via cation exchange at low initial acidities ([UO 2 (TBP) n ] 2+ versus C 4 -mim + and H + ) 15 and via anion exchange at high HNO 3 concentrations ([(UO 2 (NO 3 ) 3 (TBP) m ] − versus Tf 2 N − ). By contrast to the usual TBP/dodecane organic phase, the IL system does not favor the neutral species UO 2 (NO 3 ) 2 (TBP) 2 , and TBP does not extract nitric acid.
Separation Science and Technology, 2005
Ionic liquids have been proposed as replacements for volatile organic solvents (VOSs) by a range of authors, due to their very low vapor pressure, ability to dissolve a range of organic, inorganic, and organometallic compounds, immiscibility with water, and ability to form biphasic systems depending on the choice of cation/ anion combination making up the ionic liquid. In this study the room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF 6 ] was synthesized and a range of physical properties including the interfacial tension, viscosity, and density determined. The distribution of tyramine and 2-methoxyphenethylamine (MPEA) as a function of pH was determined for the [bmim][PF 6 ] system. This was compared to distribution data obtained for these solutes in conventional organic
Correlation and prediction of solubility of hydrogen in alkenes and its dissolution properties
Applied Petrochemical Research
In this work, solubility of hydrogen in some alkenes was investigated at different temperatures and pressures. Solubility values were calculated using the Peng–Robinson equation of state. Binary interaction parameters were calculated using fitting the equation of state on experimental data, Group contribution method and Moysan correlations and total average absolute deviation for these methods was 3.90, 17.60 and 13.62, respectively. Because hydrogen solubility in Alkenes is low, Henry’s law for these solutions were investigated, too. Results of calculation showed with increasing temperature, Henry’s constant was decreased. The temperature dependency of Henry’s constants of hydrogen in ethylene and propylene was higher than to other alkenes. In addition, using Van’t Hoff equation, the thermodynamic parameters for dissolution of hydrogen in various alkenes were calculated. Results indicated that the dissolution of hydrogen was spontaneous and endothermic. The total average of dissolu...
Green Chemistry, 2006
Using previously published toxicity data as well as a small set of heretofore-unpublished results, quantitative structure-property relationship models are developed to assess the factors that govern the toxicity of a range of different ionic liquids to two aquatic organisms (Vibrio fischeri and Daphnia magna). With at most four molecular descriptors, log 10 EC50 and log 10 LC50 data are reproduced with an R 2 of 0.78-0.88. Besides the well-established link between toxicity and alkyl chain length on imidazolium, pyridinium and quaternary ammonium-based ionic liquids, the models predict that toxicity increases slightly with the number of nitrogen atoms in an aromatic cation ring. All other things being equal, toxicity is expected to show the trend with cation type of ammonium , pyridinium , imidazolium , triazolium , tetrazolium. In addition, toxicity is expected to decrease with ring methylation as well as with an increase in the number of negatively charged atoms on the cation. The anion plays a secondary role in toxicity for the compounds studied here, although the presence of positively charged atoms on the anion are predicted to slightly increase toxicity.
Environmental safety of cholinium-based ionic liquids: assessing structure-ecotoxicity relationships
Green Chem., 2015
Ionic liquids (ILs) are innovative solvents that can be tuned for their specific application through the selection, or functionalization, of the cation and the anion. Although the cation has been assumed as the main driver of toxicity, the importance of the anion must not be underestimated. This study considers a series of cholinium based ILs aiming at assessing the effects of the functionalization of the cation and the anion on their ecotoxicity. These effects were assessed using three biological models, the microalgae Raphidocelis subcapitata, the macrophyte Lemna minor and the cladoceran Daphnia magna, representing aquatic ecosystems, a major putative recipient of ILs due to their high water solubility. Since the toxicity trends fluctuated depending on the biological model, the results were integrated with previous data through a species sensitivity distribution approach in an attempt to provide a useful safety variable for the design of eco-friendlier ILs. The results reported here challenge some heuristic rules previously proposed for the design of ILs, in particular in what concerns the side-chain effect for the cholinium ILs, and the notion that cholinium-based ILs are inherently safe and less environmentally hazardous than most conventional solvents. Moreover, it was confirmed that structural changes in the ILs promote differences in toxicity highlighting the importance of the role of the anion in their toxicity. Different biological systems yielded different toxicity trends across the IL series tested, also distinct from previous data retrieved with the bacteria V. fischeri; such a novel integration effort challenges the suitability of establishing structureecotoxicity relationships for cholinium-based IL design. Overall, this study reinforces the need to perform complete ecotoxicological characterisation before assuming ILs as suitable, environmentally compatible, alternative solvents. † Electronic supplementary information (ESI) available: Nomenclature and chemical structure of the studied compounds plus numerical values for the determined ecotoxicity references. See
Exploring the corrosion inhibition capability of FAP-based ionic liquids on stainless steel
Royal Society Open Science
Corrosion is clearly one of the more common causes of materials failure in stainless steel. To manage corrosion, chemical inhibitors are often used for prevention and control. Ionic liquids due to their hydrophobic and corrosion-resistant property are being explored as alternative protective coatings and anti-corrosion materials. In this particular study, ionic liquids containing functionalized imidazolium cations and tris(pentafluoroethyl)trifluorophosphate (FAP) anions were investigated for their ability to inhibit corrosion on stainless steel surfaces in acidic environment. Using surface characterization techniques, specifically scanning electron microscopy and energy-dispersive X-ray (EDX), the morphology and the elemental composition of the steel surfaces before and after corrosion were determined. Contact angle measurements were also performed to determine how these ionic liquids were able to wet the stainless steel surface. In addition, potentiodynamic studies were carried ou...
Water-clustering in hygroscopic ionic liquids-an implicit solvent analysis
2012
Most ionic liquids are known to be hygroscopic to varying degrees, and that can be detrimental or useful depending upon the application in question. Water can accumulate slowly over hours or days to saturation levels corresponding to the humidity level. When designing or deploying a new ionic liquid it is important to be able to estimate its maximum moisture absorbing ability at the temperature and pressure of its operation. With this goal in mind we have carried out computational studies on three ionic liquid systems based on [BF 4 ] À , [PF 6 ] À , and [Tf 2 N] À anions and 1-alkyl-3-methyl-imidazolium ([C n mim] +) cations within an implicit solvent formalism. For highly hygroscopic systems like [C n mim][BF 4 ] we find that non-iterative calculations with single water molecules can lead to significant underestimation of the maximum moisture content, while iterative calculations can result in miscibility behavior qualitatively different from experimental observations. On the other hand, the inclusion of small hydrogen-bonded water-clusters up to an appropriately chosen size is shown to yield better quantitative agreements with experimentally observed water uptake. Additionally, such calculations appear consistent with a number of thermodynamically interesting phase behaviors, including limited-solubility to full-miscibility transitions as a function of temperature and as a function of the alkyl chain length of the imidazolium cation. For hydrophobic systems like [C n mim][PF 6 ] and [C n mim][Tf 2 N] the computed solubility (for each n) is found to have a smooth convergence behavior as a function of the largest cluster-size considered with the results for the larger clusters being close to that obtained by iterative calculations with single water molecules.
Sugar-Based Ionic Liquids: Multifaceted Challenges and Intriguing Potential
2021
Carbohydrates represent a promising option in transitioning from oil-based chemical resources to renewable ones, with the goal of developing chemistries for a sustainable future. Cellulose, hemicellulose, and largely available monosaccharides already provide useful chemical building blocks, so-called platform chemicals, such as levulinic acid and hydroxymethyl furfural, as well as solvents like cyrene or gamma-valerolactone. Therefore, there is great anticipation for novel applications involving materials and chemicals derived from sugars. In the field of ionic liquids (ILs), sugar-based ILs have been overlooked for a long time, mainly on account of their multistep demanding preparation. However, exploring new strategies for accessing sugar-based ILs, their study, and their exploitation, are attracting increasing interest. This is due to the growing concerns about the negative (eco)toxicity profile of most ILs in conjunction with their non-sustainable nature. In the present review, ...
Physical chemistry chemical physics : PCCP, 2017
We study the properties of residual water molecules at different mole fractions in dialkylimidazolium based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM/BF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM/BF4) by means of atomistic molecular dynamics (MD) simulations. The corresponding Kirkwood-Buff (KB) integrals for the water-ion and ion-ion correlation behavior are calculated by a direct evaluation of the radial distribution functions. The outcomes are compared to the corresponding KB integrals derived by an inverse approach based on experimental data. Our results reveal a quantitative agreement between both approaches, which paves a way towards a more reliable comparison between simulation and experimental results. The simulation outcomes further highlight that water even at intermediate mole fractions has a negligible influence on the ion distribution in the solution. More detailed analysis on the local/bulk partition coefficients and...
Gd3+ complexes conjugated to Pittsburgh compound B: potential MRI markers of β-amyloid plaques
JBIC Journal of Biological Inorganic Chemistry, 2014
In an effort towards the visualization of b-amyloid (Ab) plaques by T 1 -weighted magnetic resonance imaging for detection of Alzheimer's disease, we report the synthesis and characterization of stable, noncharged Gd 3? complexes of three different 1,4,7,10tetraazacyclododecane-1,4,7-triacetic acid monoamide derivatives conjugated to Pittsburgh compound B, a wellestablished marker of Ab plaques. The ligands L 1 , L 2 , and L 3 differ in the nature and size of the spacer linking the macrocyclic chelator and the Pittsburgh compound B targeting moiety, which affects their lipophilicity, the octanol-water partition coefficients of the complexes ranging from -0.15 to 0.32. Given their amphiphilic behavior, the complexes form micelles in aqueous solution (critical micellar concentration 1.00-1.49 mM). The parameters determining the relaxivity, including the water exchange rate and the rotational correlation times, were assessed for the monomeric and the micellar form by a combined 17 O NMR and 1 H nuclear magnetic relaxation dispersion (NMRD) study. They are largely influenced by the aggregation state and the hydrophobic character of the linkers. The analysis of the rotational dynamics for the aggregated state in terms of local and global motions using the Lipari-Szabo approach indicates highly flexible, large aggregates. On binding of the complexes to human serum albumin or to the amyloid peptide Ab 1-40 in solution, they undergo a fourfold and a twofold relaxivity increase, respectively (40 MHz). Proton relaxation enhancement studies confirmed moderate interaction of Gd(L 1 ) and Gd(L 3 ) with human serum albumin, with K A values ranging between 250 and 910 M -1 .
Analytical and Bioanalytical Chemistry, 2011
The partition coefficients, P IL/w , for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF 6 ], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF 6 ], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF 4 ] and water were accurately measured. [BMIM][PF 6 ] and [OMIM][BF 4 ] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a much lesser consumption of organic solvent. We employed the solvation-parameter model to elucidate the general chemical interactions involved in RTIL/water partitioning. With this purpose, we have selected different solute descriptor parameters that measure polarity, polarizability, hydrogen-bonddonor and hydrogen-bond-acceptor interactions, and cavity formation for a set of specifically selected probe molecules (the training set). The obtained multiparametric equations were used to predict the partition coefficients for compounds not present in the training set (the test set), most being of biological interest. Partial solubility of the ionic liquid in water (and water into the ionic liquid) was taken into account to explain the obtained results. This fact has not been deeply considered up to date. Solute descriptors were obtained from the literature, when available, or else calculated through commercial software. An excellent agreement between calculated and experimental log P IL/w values was obtained, which demonstrated that the resulting multiparametric equations are robust and allow predicting partitioning for any organic molecule in the biphasic systems studied.
Using Monte Carlo simulation to compute osmotic coefficients of aqueous solutions of ionic liquids
Chemical Physics, 2010
We perform, for the first time to our knowledge, Monte Carlo simulation to compute osmotic coefficient of ionic liquid aqueous solutions. The ionic liquids chosen are 1-ethyl-3-methylimidazolium bromide [Emim][Br], 1-methyl-3-methylimidazolium chloride [Mmim][Cl], 1-methyl-3-methylimidazolium bromide [Mmim][Br], 1-methyl-3-methylimidazolium iodide [Mmim][I] and 1-methyl-3-methylimidazolium hexafluorophosphate [Mmim][PF 6 ]. Simulations are carried out in the NVT ensemble at 298.15 K. The Unrestricted Primitive Model (UPM) of electrolyte is used as microscopic model in simulation process. Accuracy of simulation to predict osmotic coefficients is verified by a direct comparison of simulation results with experimental data. Computed osmotic coefficients are in good agreement with available experimental values.
Physical Properties of Ionic Liquids: Database and Evaluation
Journal of Physical and Chemical Reference Data, 2006
A comprehensive database on physical properties of ionic liquids ͑ILs͒, which was collected from 109 kinds of literature sources in the period from 1984 through 2004, has been presented. There are 1680 pieces of data on the physical properties for 588 available ILs, from which 276 kinds of cations and 55 kinds of anions were extracted. In terms of the collected database, the structure-property relationship was evaluated. The correlation of melting points of two most common systems, disubstituted imidazolium tetrafluoroborate and disubstituted imidazolium hexafluorophosphate, was carried out using a quantitative structure-property relationship method.
Composition and structural effects on the adsorption of ionic liquids onto activated carbon
Environmental science. Processes & impacts, 2013
The applications and variety of ionic liquids (ILs) have increased during the last few years, and their use at a large scale will require their removal/recovery from wastewater streams. Adsorption on activated carbons (ACs) has been recently proposed for this aim and this work presents a systematic analysis of the influence of the IL chemical structures (cation side chain, head group, anion type and the presence of functional groups) on their adsorption onto commercial AC from water solution. Here, the adsorption of 21 new ILs, which include imidazolium-, pyridinium-, pyrrolidinium-, piperidinium-, phosphonium- and ammonium-based cations and different hydrophobic and hydrophilic anions, has been experimentally measured. This contribution allows an expansion of the range of IL compounds studied in previous works, and permits a better understanding of the influence of the IL structures through the adsorption on AC. In addition, the COSMO-RS method was used to analyze the measured adso...
Improved recovery of ionic liquids from contaminated aqueous streams using aluminium-based salts
RSC Advances, 2012
The number of applications involving ionic liquids has dramatically increased in the past few years, and their production and use in a large scale will inevitably lead to their dispersion into water streams (either by wastewater disposal or accidental leakage). Studies on the removal and recovery of ionic liquids from wastewater streams are therefore of crucial importance, yet particularly scarce. In this work, the use of aluminium salts is proposed to concentrate and remove ionic liquids from aqueous solutions. Two aluminium-based salts (Al 2 (SO 4) 3 and AlK(SO 4) 2 ?12H 2 O) were used to treat various aqueous solutions of ionic liquids containing imidazolium-, pyridinium-and phosphonium-based fluids. The gathered results show the enhanced ability of these salts to remove and recover ionic liquids from aqueous media. The minimum recovery efficiency achieved was 96%, whereas for a large array of systems recoveries of circa 100% of ionic liquid were attained. The residual concentrations of ionic liquids in water range from 0.01 to 6 wt%. The results reported disclose a novel promising technique for the recovery and treatment of aqueous effluents contaminated with ionic liquids by using salts commonly employed in water treatment processes, allowing thus its easy scale-up and adaptation to new processes involving ionic liquids.
CO2 Electroreduction in Ionic Liquids
Frontiers in Chemistry, 2019
CO 2 electroreduction is among the most promising approaches used to transform this greenhouse gas into useful fuels and chemicals. Ionic liquids (ILs) have already proved to be the adequate media for CO 2 dissolution, activation, and stabilization of radical and ionic electrochemical active species in aqueous solutions. In general, IL electrolytes reduce the overpotential, increase the current density, and allow for the modulation of solution pH, driving product selectivity. However, little is known about the main role of these salts in the CO 2 reduction process the assumption that ILs form solvent-separated ions. However, most of the ILs in solution are better described as anisotropic fluids and display properties of an extended cooperative network of supramolecular species. That strongly reflects their mesoscopic and nanoscopic organization, inducing different processes in CO 2 reduction compared to those observed in classical electrolyte solutions. The major aspects concerning the relationship between the structural organization of ILs and the electrochemical reduction of CO 2 will be critically discussed considering selected recent examples.
Aqueous dye-sensitized solar cells
Chemical Society Reviews, 2015
This review highlights the efforts towards the realization of an artificial photosynthetic system able to convert sunlight into electricity by using a unique solvent, water, the solvent of life.
The Path Ahead for Ionic Liquids
Chemical Engineering & Technology, 2007
Ionic liquids are designer molecules which can efficiently replace the conventional organic solvents used in chemical processes and operations. Although a number of such applications have been reported in the literature for almost a decade, very few have actually been commercialized. This paper details the different applications claimed and examines the issues and barriers which obstruct the rapid commercialization of ionic liquids. It identifies further courses of action required for the assessment and realization of the advantages of ionic liquids.
Separations, 2019
There are many advantages to using ionic liquids as solvents or catalysts in chemical processes. Their non-volatile characteristic and high cost, however, can pose economic, environmental, and long-term health concerns. As such, the recovery and recycling of ionic liquids have become essential to mitigate their environmental impact and to reduce costs. Numerous recovery and recycling methods have been reported, including distillation, extraction, membrane separation (a.k.a. filtration), adsorption, crystallization, gravity, and electrochemical separation. Whereas most of these methods recover both cations and anions of the ionic liquid as ion pairs, recycling methods such as single-phase ion exchange or mixed-ion exchange/non-ionic adsorption methods recover only one of the ionic liquid ions, typically the cation. These methods are frequently used for the recycling of ionic liquids having simple anions such as chloride or acetate, but are seldom employed for ionic liquids consisting...